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Source PDF: /mnt/main/jmc-storage/docs/DVB/ETSI 301 199 Interaction channel for Local Multi-point Distribution Systems (LMDS) (1999-06).pdf Like all conversions the text below should be fully readable as UTF-8 unicode text. --------------------------------------------------------------- EN 301 199 V1.2.1 (1999-06) European Standard (Telecommunications series) Digital Video Broadcasting (DVB); Interaction channel for Local Multi-point Distribution Systems (LMDS) European Broadcasting Union Union Européenne de Radio-Télévision EBU UER 2 ETSI EN 301 199 V1.2.1 (1999-06) Reference REN/JTC-DVB-79 (b3o00ioo.PDF) Keywords DVB, digital, video, broadcasting, interaction, TV ETSI Postal address F-06921 Sophia Antipolis Cedex - FRANCE Office address 650 Route des Lucioles - Sophia Antipolis Valbonne - FRANCE Tel.: +33 4 92 94 42 00 Fax: +33 4 93 65 47 16 Siret N° 348 623 562 00017 - NAF 742 C Association à but non lucratif enregistrée à la Sous-Préfecture de Grasse (06) N° 7803/88 Internet secretariat@etsi.fr Individual copies of this ETSI deliverable can be downloaded from http://www.etsi.org If you find errors in the present document, send your comment to: editor@etsi.fr Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the foregoing restriction extend to reproduction in all media. © European Telecommunications Standards Institute 1999. © European Broadcasting Union 1999. All rights reserved. ETSI 3 ETSI EN 301 199 V1.2.1 (1999-06) Contents Intellectual Property Rights ............................................................................................................................... 6 Foreword ............................................................................................................................................................ 6 1 Scope........................................................................................................................................................ 7 2 References ............................................................................................................................................... 7 3 Abbreviations........................................................................................................................................... 8 4 Reference Model for System Architecture of Narrowband Interaction Channels in a Broadcasting Scenario (Asymmetric Interactive Services) ........................................................................................... 9 4.1 Protocol Stack Model ........................................................................................................................................ 9 4.2 System Model .................................................................................................................................................. 10 5 DVB Interaction Channel Specification for LMDS Networks.............................................................. 13 5.1 System Concept ............................................................................................................................................... 13 5.1.1 Out-Of-Band / In-Band Principle ............................................................................................................... 13 5.1.2 Spectrum Allocation................................................................................................................................... 14 5.1.3 FDMA/TDMA Multiple Access................................................................................................................. 15 5.1.4 Bit Rates and Framing................................................................................................................................ 16 5.2 Lower Physical Layer Specification ................................................................................................................ 17 5.2.1 Forward Interaction Path (Downstream OOB)........................................................................................... 19 5.2.1.1 Frequency Range (Downstream OOB) ................................................................................................. 19 5.2.1.2 Modulation and Mapping (Downstream OOB) .................................................................................... 19 5.2.1.3 Shaping Filter (Downstream OOB) ...................................................................................................... 20 5.2.1.4 Randomizer (Downstream OOB) ......................................................................................................... 21 5.2.1.5 Bit Rate (Downstream OOB)................................................................................................................ 21 5.2.1.6 Receiver Power Level (Downstream OOB) (informative).................................................................... 21 5.2.1.7 Summary (Downstream OOB).............................................................................................................. 22 5.2.1.8 Bit Error Rate Downstream OOB (Informative)................................................................................... 22 5.2.2 Forward Interaction Path (Downstream IB) ............................................................................................... 23 5.2.3 Return Interaction Path (Upstream)............................................................................................................ 23 5.2.3.1 Frequency Range (Upstream) ............................................................................................................... 23 5.2.3.2 Modulation and Mapping (Upstream) .................................................................................................. 23 5.2.3.3 Shaping Filter (Upstream) .................................................................................................................... 24 5.2.3.4 Randomizer (Upstream)........................................................................................................................ 25 5.2.3.5 Bit Rate (Upstream).............................................................................................................................. 25 5.2.3.6 Transmit Power Level (Upstream) (informative).................................................................................. 26 5.2.3.7 Upstream Burst Power and Timing Profiles ......................................................................................... 26 5.2.3.8 Interference (Spurious) Suppression..................................................................................................... 26 5.2.3.9 Summary (Upstream)............................................................................................................................ 27 5.2.3.10 Packet Loss Upstream (Informative) .................................................................................................... 28 5.2.3.11 Maximum Delay ................................................................................................................................... 28 5.3 Framing............................................................................................................................................................ 28 5.3.1 Forward Interaction Path (Downstream OOB)........................................................................................... 28 5.3.1.1 Signalling Link Extended Superframe Framing Format ....................................................................... 28 5.3.1.2 Frame overhead .................................................................................................................................... 29 5.3.1.3 Payload Structure.................................................................................................................................. 30 5.3.2 Forward Interaction Path (Downstream IB) ............................................................................................... 37 5.3.2.1 IB Signalling MPEG2-TS Format (MAC Control Message)................................................................ 37 5.3.2.2 Frequency of IB Signalling Information ............................................................................................... 39 5.3.3 Return Interaction Path (Upstream)............................................................................................................ 40 5.3.3.1 Slot Format ........................................................................................................................................... 40 5.3.4 Minimum Processing Time ........................................................................................................................ 41 5.4 Slot Timing Assignment .................................................................................................................................. 42 5.4.1 Downstream Slot Position Reference (Downstream OOB)........................................................................ 42 5.4.2 Downstream Slot Position Reference (Downstream IB) ............................................................................ 42 ETSI 4 ETSI EN 301 199 V1.2.1 (1999-06) 5.4.3 Upstream Slot Positions ............................................................................................................................. 44 5.4.3.1 Rate 256 kbit/s...................................................................................................................................... 44 5.4.3.2 Void...................................................................................................................................................... 44 5.4.3.3 Rate 1,544 Mbit/s ................................................................................................................................. 44 5.4.3.4 Rate 3,088 Mbit/s ................................................................................................................................. 45 5.4.3.5 Rate 6,176 Mbit/s ................................................................................................................................. 46 5.4.4 Slot Position Counter ................................................................................................................................. 47 5.5 MAC Functionality .......................................................................................................................................... 48 5.5.1 MAC Reference Model .............................................................................................................................. 48 5.5.2 MAC Concept ............................................................................................................................................ 48 5.5.2.1 Relationship Between Higher Layers and MAC Protocol .................................................................... 48 5.5.2.2 Relationship Between Physical Layer and MAC Protocol ................................................................... 49 5.5.2.3 Relationship Between Physical Layer Slot Position Counter and MAC Slot Assignment.................... 51 5.5.2.4 Access Modes (Contention / Ranging / Fixed rate / Reservation) ........................................................ 51 5.5.2.5 MAC Error Handling Procedures ......................................................................................................... 52 5.5.2.6 MAC Messages in the Mini Slots ......................................................................................................... 52 5.5.2.7 MAC Message Format.......................................................................................................................... 55 5.5.3 MAC Initialization and Provisioning ......................................................................................................... 58 5.5.3.1 Provisioning Channel Message (Broadcast OOB Downstream) ............................................ 59 5.5.3.2 Default Configuration Message (Broadcast Downstream) ..................................................... 60 5.5.4 Sign On and Calibration............................................................................................................................. 64 5.5.4.1 Sign-On Request Message (Broadcast Downstream) ............................................................. 65 5.5.4.2 Sign-On Response Message (Upstream Ranging).................................................................. 66 5.5.4.3 Ranging and Power Calibration Message (Singlecast Downstream)...................................... 68 5.5.4.4 Ranging and Power Calibration Response Message (Upstream Ranging or reserved) .......... 70 5.5.4.5 Initialization Complete Message (Singlecast Downstream) ................................................... 70 5.5.4.6 Frequency ranging ................................................................................................................................ 71 5.5.5 Connection Establishment .......................................................................................................................... 71 5.5.5.1 Establishment of the First (Initial) Connection..................................................................................... 72 5.5.5.2 Establishment of Additional Connections............................................................................................. 77 5.5.6 Connection Release .................................................................................................................................... 79 5.5.7 Fixed Rate Access ...................................................................................................................................... 80 5.5.8 Contention Based Access ........................................................................................................................... 80 5.5.9 Reservation Access .................................................................................................................................... 81 5.5.10 MAC Link Management............................................................................................................................. 86 5.5.10.1 Power and Timing Management........................................................................................................... 86 5.5.10.2 TDMA Allocation Management ........................................................................................................... 86 5.5.10.3 Channel Error Management.................................................................................................................. 89 5.5.10.4 Link Management Messages................................................................................................................. 90 5.6 Minislots .......................................................................................................................................................... 97 5.6.1 Carrying Minislots...................................................................................................................................... 97 5.6.2 Minislot framing structure.......................................................................................................................... 98 5.6.3 Contention resolution for minislots ............................................................................................................ 98 5.7 Security (optional) ........................................................................................................................................... 99 5.7.1 Cryptographic primitives.......................................................................................................................... 100 5.7.1.1 Public key exchange ........................................................................................................................... 100 5.7.1.2 Hashing............................................................................................................................................... 100 5.7.1.3 Encryption .......................................................................................................................................... 101 5.7.1.4 Pseudo-random numbers .................................................................................................................... 101 5.7.2 Main Key Exchange, MKE ...................................................................................................................... 101 5.7.3 Quick Key Exchange, QKE...................................................................................................................... 102 5.7.4 Explicit Key Exchange, EKE ................................................................................................................... 102 5.7.5 Key derivation.......................................................................................................................................... 103 5.7.6 Data stream processing............................................................................................................................. 103 5.7.6.1 Payload streams .................................................................................................................................. 103 5.7.6.2 Data encryption .................................................................................................................................. 103 5.7.6.3 Encryption flags.................................................................................................................................. 104 5.7.6.4 Chaining and initialization vector....................................................................................................... 104 5.7.7 Security Establishment ............................................................................................................................. 104 5.7.8 Persistent state variables........................................................................................................................... 105 ETSI 5 ETSI EN 301 199 V1.2.1 (1999-06) 5.7.8.1 Guaranteed delivery............................................................................................................................ 105 5.7.9 Security MAC Messages .......................................................................................................................... 106 5.7.9.1 Security Sign-On (Single-cast Downstream)......................................................................... 106 5.7.9.2 Security Sign-On Response (Upstream)................................................................................ 107 5.7.9.3 Main Key Exchange (Single-cast Downstream).................................................................... 107 5.7.9.4 Main Key Exchange Response (Upstream)........................................................................... 108 5.7.9.5 Quick Key Exchange (Single-cast Downstream)................................................................... 109 5.7.9.6 Quick Key Exchange Response (Upstream).......................................................................... 109 5.7.9.7 Explicit Key Exchange (Single-cast Downstream)................................................................ 110 5.7.9.8 Explicit Key Exchange Response (Upstream)....................................................................... 110 5.7.9.9 Wait (Upstream).................................................................................................................... 111 6 Interactive STB / Data Modem Mid Layer Protocol ........................................................................... 111 6.1 Direct IP......................................................................................................................................................... 111 6.1.1 Framing .................................................................................................................................................... 112 6.1.1.1 Upstream and OOB Downstream ....................................................................................................... 112 6.1.1.2 IB Downstream................................................................................................................................... 112 6.1.2 Addressing ............................................................................................................................................... 112 6.1.2.1 IP Broadcast and Multicast from STB/NIU to INA............................................................................ 112 6.1.2.2 IP Broadcast and Multicast from INA to STB/NIU............................................................................ 112 6.1.3 IP Address Assignment ............................................................................................................................ 112 6.1.4 INA Interfaces (informative).................................................................................................................... 113 6.1.5 NIU/STB Interfaces (informative) ........................................................................................................... 113 6.2 Ethernet MAC Bridging................................................................................................................................. 113 6.2.1 Framing .................................................................................................................................................... 113 6.2.1.1 Upstream and OOB Downstream ....................................................................................................... 113 6.2.1.2 IB Downstream................................................................................................................................... 113 6.2.2 Addressing ............................................................................................................................................... 113 6.3 PPP ................................................................................................................................................................ 113 6.3.1 Framing .................................................................................................................................................... 113 6.3.1.1 Upstream and OOB Downstream ....................................................................................................... 113 6.3.1.2 IB Downstream................................................................................................................................... 114 6.3.2 Addressing ............................................................................................................................................... 114 6.3.3 IP Address Assignment ............................................................................................................................ 114 6.3.4 Additional IP addresses............................................................................................................................ 114 6.3.5 Security .................................................................................................................................................... 114 6.3.6 INA Interfaces (informative).................................................................................................................... 114 6.3.7 NIU/STB Interfaces (informative) ........................................................................................................... 114 Annex A (informative): MAC State Transitions and Time Outs .................................................... 115 A.1 Ranging and Calibration ...................................................................................................................... 115 A.2 Connection Establishment ................................................................................................................... 119 A.3 Connection Release ............................................................................................................................. 120 A.4 Reservation Process............................................................................................................................. 121 A.5 Re-calibration ...................................................................................................................................... 124 A.6 Reprovision Message........................................................................................................................... 124 A.7 Transmission Control Message ........................................................................................................... 124 A.8 Status Request Message....................................................................................................................... 125 A.9 Idle Message ........................................................................................................................................ 125 Bibliography .................................................................................................................................................. 126 History............................................................................................................................................................ 127 ETSI 6 ETSI EN 301 199 V1.2.1 (1999-06) Intellectual Property Rights IPRs essential or potentially essential to the present document may have been declared to ETSI. The information pertaining to these essential IPRs, if any, is publicly available for ETSI members and non-members, and can be found in SR 000 314: "Intellectual Property Rights (IPRs); Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards", which is available free of charge from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http://www.etsi.org/ipr). Pursuant to the ETSI IPR Policy, no investigation, including IPR searches, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may become, essential to the present document. Foreword This European Standard (Telecommunications series) has been produced by the Joint Technical Committee (JTC) Broadcast of the European Broadcasting Union (EBU), Comité Européen de Normalisation ELECtrotechnique (CENELEC) and the European Telecommunications Standards Institute (ETSI). NOTE: The EBU/ETSI JTC Broadcast was established in 1990 to co-ordinate the drafting of standards in the specific field of broadcasting and related fields. Since 1995 the JTC Broadcast became a tripartite body by including in the Memorandum of Understanding also CENELEC, which is responsible for the standardization of radio and television receivers. The EBU is a professional association of broadcasting organizations whose work includes the co-ordination of its members' activities in the technical, legal, programme-making and programme-exchange domains. The EBU has active members in about 60 countries in the European broadcasting area; its headquarters is in Geneva. European Broadcasting Union CH-1218 GRAND SACONNEX (Geneva) Switzerland Tel: +41 22 717 21 11 Fax: +41 22 717 24 81 Founded in September 1993, the DVB Project is a market-led consortium of public and private sector organizations in the television industry. Its aim is to establish the framework for the introduction of MPEG-2 based digital television services. Now comprising over 200 organizations from more than 25 countries around the world, DVB fosters market-led systems, which meet the real needs, and economic circumstances, of the consumer electronics and the broadcast industry. National transposition dates Date of adoption of this EN: 28 May 1999 Date of latest announcement of this EN (doa): 31 August 1999 Date of latest publication of new National Standard or endorsement of this EN (dop/e): 29 February 2000 Date of withdrawal of any conflicting National Standard (dow): 29 February 2000 ETSI 7 ETSI EN 301 199 V1.2.1 (1999-06) 1 Scope The present document is the baseline specification for the provision of the interaction channel for LMDS networks. This version supersedes the previous version 1.1.1 of this standard. It is not intended to specify a return channel solution associated to each broadcast system because the inter-operability of different delivery media to transport the return channel is desirable. The solutions provided in the present document for interaction channel for LMDS networks are a part of a wider set of alternatives to implement interactive services for Digital Video Broadcasting (DVB) systems. The present document is not limited to a given frequency range. All the frequencies refer to IF frequencies as defined in subclause 5.1.2. 2 References The following documents contain provisions which, through reference in this text, constitute provisions of the present document. • References are either specific (identified by date of publication, edition number, version number, etc.) or non-specific. • For a specific reference, subsequent revisions do not apply. • For a non-specific reference, the latest version applies. • A non-specific reference to an ETS shall also be taken to refer to later versions published as an EN with the same number. [1] ITU-T Recommendation I.432: "B-ISDN User-Network Interface - Physical layer specification". [2] ETS 300 800: "Digital Video Broadcasting (DVB); Interaction channel for Cable TV distribution systems (CATV)". [3] EN 301 192: "Digital Video Broadcasting (DVB); DVB specification for data broadcasting". [4] EN 300 421: "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for 11/12 GHz satellite services". [5] TR 100 815: "Digital Video Broadcasting (DVB); Guidelines for the handling of ATM signals in DVB systems". [6] EN 300 468: "Digital Video Broadcasting (DVB); Specification for Service Information (SI) in DVB systems". [7] ITU-T Recommendation I.361: "B-ISDN ATM layer specification". [8] ITU-T Recommendation I.363: "B-ISDN ATM Adaptation Layer specification". [9] ISO 13818-1: "Information technology - Generic coding of moving pictures and associated audio information: Systems". [10] ISO/IEC 8802-3 (1996): "Information technology - Telecommunications and information exchange between systems - Local and metropolitan area networks - Specific requirements - Part 3: Carrier sense multiple access with collision detection (CSMA/CD) access method and physical layer specifications". [11] IETF RFC 2104, Krawczyk, et. al: "HMAC: Keyed-Hashing for Message". [12] IETF RFC 2236: "IGMP protocol". ETSI 8 ETSI EN 301 199 V1.2.1 (1999-06) [13] IETF RFC 1483: "Multiprotocol encapsulation over ATM adapt. layer 5". [14] IETF RFC 2131: "Dynamic host configuration protocol (DHCP)". [15] IETF RFC 951: "Bootstrap protocol (BOOTP)". [16] IETF RFC 791: "Internet protocol". [17] ATMF UNI 3.1 ATM Forum User-Network Interface, Version 3.1. 3 Abbreviations For the purposes of the present document, the following abbreviations apply: ATM Asynchronous Transfer Mode BC Broadcast Channel BRA Basic Rate Access LMDS Local Multipoint Distribution System CBC Cipher Block Chaining Connection ID Connection Identificator CM Cable Modem D-H Diffie-Hellman DAVIC Digital Audiovisual Council DCE Data Communication Equipment DES Data Encryption Standard DTE Data Termination Equipment DTMF Dual Tone Multifrequency (dialling mode) DVB Digital Video Broadcasting EKE Explicit Key Exchange GSTN General Switched Telephone Network HMAC Hash-based Message Authentication Code IB In-Band IC Interaction Channel INA Interactive Network Adapter IRD Integrated Receiver Decoder ISDN Integrated Services Digital Network IQ In-phase and Quadrature Components IV Initialization Vector LFSR Linear Feedback Shift Register LSB Least Significant Bit MAC Media Access Control MKE Main Key Exchange MMDS Multi-channel Multi-point Distribution Systems MPEG Moving Pictures Experts Group MTU Maximum Transmission Unit NIU Network Interface Unit NSAP Network Service Access Point OOB Out of Band OSI Open Systems Interconnection PID Packet Identifier (defined by ISO/IEC 13818 (MPEG-2) [9]) PM Pulse Modulation PSTN Public Switched Telephone Network QAM Quadrature Amplitude Modulation QKE Quick Key Exchange QoS Quality of Service QPSK Quaternary Phase Shift Keying Reservation ID Reservation Identificator SHA-1 Secure Hash Algorithm 1 SMATV Satellite Master Antenna Television STB Set Top Box ETSI 9 ETSI EN 301 199 V1.2.1 (1999-06) STU Set Top Unit TDMA Time Division Multiplex Access TS Transport Stream VCI ATM Virtual Channel Identification (defined by ITU-T Recommendation I.363 [8]) VPI ATM Virtual Path Identification (defined by ITU-T Recommendation I.363 [8]) 4 Reference Model for System Architecture of Narrowband Interaction Channels in a Broadcasting Scenario (Asymmetric Interactive Services) 4.1 Protocol Stack Model For asymmetric interactive services supporting broadcast to the home with narrowband return channel, a simple communications model consists of the following layers: physical layer: where all the physical (electrical) transmission parameters are defined. transport layer: defines all the relevant data structures and communication protocols like data containers, etc. application layer: is the interactive application software and runtime environments (e.g. home shopping application, script interpreter, etc.). A simplified model of the OSI layers was adopted to facilitate the production of specifications for these nodes. Figure 1 points out the lower layers of the simplified model and identifies some of the key parameters for the lower two layers. Following the user requirements for interactive services, no attempt will be made to consider higher layers in the present document. Layer Structure for Generic System Reference Model Proprietary layers Higher medium layers Network Independent Protocols Access mechanism Packet structure (Network Dependent Modulation Channel coding Protocols) Freq. range Filtering Equalisation Power Figure 1: Layer structure for generic system reference model This specification addresses the LMDS network specific aspects only. ETSI 10 ETSI EN 301 199 V1.2.1 (1999-06) 4.2 System Model Figure 2a shows the system model which is to be used within DVB for interactive services. In the system model, two channels are established between the Service provider and the User: - Broadcast channel (BC): A unidirectional broadband Broadcast Channel including video, audio and data. BC is established from the service provider to the users. It may include the Forward Interaction path. - Interaction channel (IC): A Bi-directional Interaction Channel is established between the service provider and the user for interaction purposes. It is formed by: - Return Interaction path: (Return Channel): From the User to the Service Provider. It is used to make requests to the service provider or to answer questions. It is a narrowband channel. Also commonly known as return channel. - Forward Interaction path: From the service provider to the user. It is used to provide some sort of information by the service provider to the user and any other required communication for the interactive service provision. It may be embedded into the broadcast channel. It is possible that this channel is not required in some simple implementations which make use of the Broadcast Channel for the carriage of data to the user. The user terminal is formed by the Network Interface Unit (NIU) (consisting of the Broadcast Interface Module (BIM) and the Interactive Interface Module (IIM)) and the Set Top Unit (STU). The user terminal provides interface for both broadcast and interaction channels. The interface between the user terminal and the interaction network is via the Interactive Interface Module. ETSI 11 ETSI EN 301 199 V1.2.1 (1999-06) Figure 2a: A generic system Reference Model for Interactive Systems ETSI 12 ETSI EN 301 199 V1.2.1 (1999-06) A1 A3 A4 INA IF/ ON AIR ODU STB TRANSMISSION RF B1 B2 B4 ODU : OUTDOOR UNIT A1, A4, B1, B4 : IF INTERFACES B2, A3 : RF INTERFACES Figure 2b: Position of IF and RF reference points in the particular case of LMDS networks ETSI 13 ETSI EN 301 199 V1.2.1 (1999-06) 5 DVB Interaction Channel Specification for LMDS Networks The LMDS infrastructures can support the implementation of the Return Channel for interactive services suitable for DVB broadcasting systems. LMDS can be used to implement interactive services in the DVB environment, providing a bi-directional communication path between the user terminal and the service provider. 5.1 System Concept The interactive system is composed of Forward Interaction path (downstream) and Return Interaction path (upstream). The general concept is to use downstream transmission from the INA to the NIUs to provide synchronization and information to all NIUs. This allows the NIUs to adapt to the network and send synchronized information upstream. Upstream transmission is divided into time slots which can be used by different users, using the technique of Time Division Multiple Access (TDMA). One downstream channel is used to synchronize up to 8 upstream channels, which are all divided into time slots. A counter at the INA is sent periodically to the NIUs, so that all NIUs work with the same clock. This gives the opportunity to the INA to assign time slots to different users. Three major access modes are provided with this system. The first one is based on contention access, which lets users send information at any time with the risk to have a collision with other user's transmissions. The second and third modes are contention-less based, where the INA either provides a finite amount of slots to a specific NIU, or a given bit rate requested by a NIU until the INA stops the connection. These access modes are dynamically shared among time slots, which allows NIUs to know when contention based transmission is or is not allowed. This is to avoid a collision for the two contention-less based access modes. Periodically, the INA will indicate to new users that they have the possibility to go through sign-on procedure, in order to give them the opportunity to synchronize their clock to the network clock, without risking collisions with already active users. This is done by leaving a larger time interval for new users to send their information, taking into account the propagation time required from the INA to the NIUs and back. 5.1.1 Out-Of-Band / In-Band Principle This interactive system is based either on out of band (OOB) or in-band (IB) downstream signalling. However, Set Top Boxes / Modems do not need to support both systems. In the case of OOB signalling, a Forward Interaction path is mandatory. This path is reserved for interactivity data and control information only. However, it is also possible to send higher bit rate downstream information through a DVB-MS channel whose frequency is indicated in the forward information path. In the case of IB signalling, the Forward Information path is embedded into the MPEG-2 TS of a DVB-MS channel. Note that it is not mandatory to include the Forward Information path in all DVB-MS channels. Both systems can provide the same quality of service. However, the overall system architecture will differ between networks using IB Set Top Boxes / Modems and OOB Set Top Boxes / Modems. Note also that both types of systems may exist on the same networks under the condition that different frequencies are used for each system. ETSI 14 ETSI EN 301 199 V1.2.1 (1999-06) 5.1.2 Spectrum Allocation The RF spectrum allocation is still to be defined and approved by the regulation bodies; the following IF frequency ranges to use are not mandatory. For downstream, both in Band and Out Of Band channels can use the 950 to 2 150 MHz frequency band. For upstream channels two different choices can be identified: 1) For the OOB signalling, In order to keep compatibility with equipment used in existing cable networks in accordance with the ETS 300 800 [2] specification, 70 to 130 MHz and 5 to 65 MHz can be used for downstream and upstream respectively. 2) For the IB signalling, taking into account the backward compatibility with the cable specifications and in order to give major capacity for the future interactive and multimedia services, the frequency allocation can be 400 to 700 MHz is 5 to 305 MHz. Figure 3c indicates a possible spectrum allocation. Although not mandatory, a guideline is provided to use the following preferred frequency ranges, 70 to 130 MHz and/or 950 to 2 150 for the Forward Interaction path (downstream OOB) and 5 to 65 MHz for the Return Interaction path (upstream), or parts thereof. To avoid filtering problems in the bi-directional video amplifiers and in the Set Top Boxes, the upper limit 65 MHz for the upstream flow shall not be used together with the lower limit 70 MHz for the downstream flow in the same system. Downstream LMDS channels 950 to 2150 MHz 70 - 130 .... Freq (MHz) 950 2150 .... QPSK interactive 2 MHz downstream OOB channels 5 - 65 MHz Upstream QPSK interactive 2 MHz upstream channels Figure 3a: DVB preferred IF frequency ranges for LMDS interactive systems (OOB) ETSI 15 ETSI EN 301 199 V1.2.1 (1999-06) Downstream LMDS channels 950 to 2150 MHz Freq (MHz) 950 2150 400 - 700 MHz Upstream QPSK interactive 2 MHz upstream channels Downstream LMDS channels 950 to 2150 MHz Freq (MHz) 950 2150 5 - 305 MHz Upstream QPSK interactive 2 MHz upstream channels Figure 3b: DVB preferred IF frequency ranges for LMDS interactive systems (IB) NOTE: The standard is applicable to any RF frequency range, according to local regulations. therefore, the frequencies specified in the present document are in the intermediate frequency range. 5.1.3 FDMA/TDMA Multiple Access A multiple access scheme is defined in order to have different users share the same transmission media. Downstream information is sent broadcast to all users of the networks. Thus, an address assignment exists for each user which allows the INA to send information singlecast to one particular user. Two addresses are stored in the Set Top Boxes / Modems in order to identify users on the network: MAC address: It is a 48-bit value representing the unique MAC address of the NIU. This MAC address may be hard coded in the NIU or be provided by external source. NSAP address: It is a 160-bit value representing a network address. This address is provided by higher layers during communication. Upstream information may come from any user in the network and shall therefore also be differentiated at the INA using the set of addresses defined above. Upstream and OOB downstream channels are divided into separate channels of 2 MHz bandwidth for downstream and 2 or 4 MHz for upstream. Each downstream channel contains a synchronization frame used by up to 8 different upstream channels, whose frequencies are indicated by the Media Access Control (MAC) protocol. ETSI 16 ETSI EN 301 199 V1.2.1 (1999-06) Within upstream channels, users send packets with TDMA type access. This means that each channel is shared by many different users, who can either send packets with a possibility of collisions when this is allowed by the INA, or request transmission and use the packets assigned by the INA to each user specifically. Assuming each channel can therefore accommodate thousands of users at the same time, the upstream bandwidth can easily be used by all users present on the network at the same time. The TDMA technique utilizes a slotting methodology which allows the transmit start times to be synchronized to a common clock source. Synchronizing the start times increases message throughput of this signalling channel since the message packets do not overlap during transmission. The period between sequential start times are identified as slots. Each slot is a point in time when a message packet can be transmitted over the signalling link. The time reference for slot location is received via the downstream channels generated at the Delivery System and received simultaneously by all set-top units. Note that this time reference is not sent in the same way for OOB and IB signalling. Since all NIU's reference the same time base, the slot times are aligned for all NIU's. However, since there is propagation delay in any transmission network, a time base ranging method accommodates deviation of transmission due to propagation delay. Since the TDMA signalling link is used by NIUs that are engaged in interactive sessions, the number of available message slots on this channel is dependent on the number of simultaneous users. When messaging slots are not in use, an NIU may be assigned multiple message slots for increased messaging throughput. Additional slot assignments are provided to the NIU from the downstream signalling information flow. There are different access modes for the upstream slots: - reserved slots with fixed rate reservation (Fixed rate Access: the user has a reservation of one or several timeslots in each frame enabling, e.g. for voice, audio); - reserved slots with dynamic reservation (Reservation Access: the user sends control information announcing his demand for transmission capacity. He gets grants for the use of slots); - contention based slots (these slots are accessible for every user. Collision is possible and solved by a contention resolution protocol); - ranging slots (these slots are used upstream to measure and adjust the time delay and the power). These slots may be mixed on a single carrier to enable different services on one carrier only. If one carrier is assigned to one specific service, only those slot types will be used which are needed for this service. 5.1.4 Bit Rates and Framing For the interactive downstream OOB channel, a transmission bit rate of 3,088 Mbit/s shall be used. The support of 3,088 Mbit/s is mandatory for both INA and NIU. For downstream IB channels, no other constraints than those specified in the DVB-MS specifications exist, but a guideline is to use rates multiples of 8 kbit/s. Downstream OOB channels continuously transmit a frame based on T1 type framing, in which some information is provided for synchronization of upstream slots. Downstream IB channels transmit some MPEG-2 TS packets with a specific PID for synchronization of upstream slots (at least one packet containing synchronization information shall be sent in every period of 3 ms). For upstream transmission, the INA can indicate two types of transmission rates to users, specifically 6,176 Mbit/s and 3,088 Mbit/s. The support of 3,088 Mbit/s is mandatory, of other rates is optional for both INA and NIU. The INA is responsible of indicating which rate may be used by NIUs. Upstream framing consists of packets of 512 bits (256 symbols) which are sent in a bursty mode from the different users present on the network. The upstream slot rates are 12 000 upstream slots when the upstream transmission bit rate is 6,176 Mbit/s, 6 000 upstream slots/s when the upstream transmission bit rate is 3,088 Mbit/s. ETSI 17 ETSI EN 301 199 V1.2.1 (1999-06) 5.2 Lower Physical Layer Specification In this subclause, detailed information is given on the lower physical layer specification. Figure 3c and Figure 4 show the conceptual block diagrams for implementation of the present specification. IF physical ATM From IF self Interface Data out RS Decoder Bit to Channel Convolutional Synchronized Differential Matched & (59, 53) Byte deinterleaver Derandomizer Decoder Filter QPSK Mapping & Demodulator Framing MAC Protocol Carrier & Clock & Synchronization To IF RS Encoder Bit to QPSK Channel Differential Addition of (59, 53) Byte Randomizer Burst Encoder Unique Word ATM Mapping Modulator Data in Figure 3c: Conceptual Block Diagram for the NIU OOB Transceiver LMDS Head-end Data To IF Convolutional ATM Randomizer Differential Baseband interface to : Modulator Channel Framing in BB Reed Byte to Interleaver Encoder Service provider source QPSK Physical Solomon Bit Multiplexers, etc. Interface Encoder Mapping MAC Protocol management carrier & Clock & Synchronization Generator From IF Data RS Decoder Bit to Channel ATM (59, 53) Byte Differential QPSK burst out Derandomizer mapping encoder Démodulator Figure 4: Conceptual Block Diagram for the OOB Head-End Transceiver ETSI 18 ETSI EN 301 199 V1.2.1 (1999-06) IF MPEG2 Sync. Physical Deinterleaver Convutional TS BB Inversion Reed Matched Decoder Symbol Interface From IF data out Physical & Solomon filter Inner to Byte & Interface Energy decoder & Mapping QPSK Burst Channel dispersal (204, 188) equalizer Demodulator removal MAC Protocol carrier & Clock & Synchronization To IF QPSK ATM Byte to Channel RS encoder Differential Addition of Burst Bit Randomizer (59, 53) Encoder Unique Word Modulator Data in Mapping Figure 5: Conceptual Block Diagram for the IB NIU Transceiver IF Physical interface MPEG2 QPSK Modulator Energy dispersal Convolutional Sync inversion To IF BB shaping - TS BB Physical I= 12 Bytes Interleaver Inner coder Channel Data in Interface RS encoder & & (204, 188) Puncturing & Mapping Baseband Interface to : Service Provider source Multiplexer, etc. MAC Protocol Management Carrier & Clock & Synchronisation RS Decoder From ATM QPSK IF Channel (59, 53) Bit to Differential Derandomizer Burst data out Byte Mapping Decoder demodulator Figure 6: Conceptual Block Diagram for the IB Head-End Transceiver ETSI 19 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.1 Forward Interaction Path (Downstream OOB) 5.2.1.1 Frequency Range (Downstream OOB) See subclause 5.1.2. 5.2.1.2 Modulation and Mapping (Downstream OOB) QPSK modulation is used as a means of encoding digital information over wireline or fibre transmission links. The method is a subset of Phase Shift Keying (PSK) which is a subset of Phase Modulation (PM). Specifically QPSK is a four level use of digital phase modulation (PM). Quadrature signal representations involve expressing an arbitrary phase sinusoidal waveform as a linear combination of a cosine wave and a sine wave with zero starting phases. QPSK systems require the use of differential encoding and corresponding differential detection. This is a result of the receivers having no method of determining if a recovered reference is a sine reference or a cosine reference. In addition, the polarity of the recovered reference is uncertain. Differential encoding transmits the information in encoded phase differences between the two successive signals. The modulator processes the digital binary symbols to achieve differential encoding and then transmits the absolute phases. The differential encoding is implemented at the digital level. The differential encoder shall accept bits A, B in sequence, and generate phase changes as follows: Table 1: Phase changes associated with bit A, B A B Phase Change 0 0 none 0 1 +90° 1 1 180° 1 0 -90° In serial mode, A arrives first. The outputs I, Q from the differential encoder map to the phase states as in Figure 7. Q 01 11 I 00 10 Figure 7: Mapping for the QPSK constellation (downstream OOB) The phase changes can also be expressed by the following formulas (assuming the constellation is mapped from I and Q as shown in 5.2.2.2):  Ak = ( I k −1 ⊕ Qk −1 ) × (Qk −1 ⊕ Qk ) + ( I k ⊕ Qk −1 ) × ( I k ⊕ I k −1 )  ,  Bk = ( I k −1 ⊕ Qk −1 ) × ( I k −1 ⊕ Ik ) + ( I k −1 ⊕ Qk ) × (Qk ⊕ Qk −1 ) where k is the time index. I/Q amplitude imbalance shall be less than 1,0 dB, and phase imbalance less than 2,0°. ETSI 20 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.1.3 Shaping Filter (Downstream OOB) The time-domain response of a square-root raised-cosine pulse with excess bandwidth parameter α is given by: πt 4 αt πt sin[ (1 − α )] + cos[ (1 + α )] g( t ) = T T T πt 4 αt 2 [1 − ( ) ] T T where T is the symbol period. The output signal shall be defined as: S(t ) = ∑ [ I n × g(t − nT ) × cos(2πfc t ) − Qn × g(t − nT ) × sin(2πfc t )] n with In and Qn equal to ± 1, independently from each other, and fc the QPSK modulator's carrier frequency. The QPSK modulator divides the incoming bit stream so that bits are sent alternately to the in-phase modulator I and the out-of- phase modulator Q. These same bit streams appear at the output of the respective phase detectors in the demodulator where they are interleaved back into a serial bit stream. The occupied bandwidth of a QPSK signal is given by the equation: fb Bandwidth = (1 + α ) 2 fb = bit rate α = excess bandwidth = 0,30 The Power Spectrum at the QPSK transmitter shall comply to the Power Spectrum Mask given in Table 2 and Figure 8. The Power Spectrum Mask shall be applied symmetrically around the carrier frequency. Table 2: QPSK Downstream Transmitter Power Spectrum | ( f - fc ) / fN | Power Spectrum ≤1-α 0 ± 0,25 dB at 1 -3 ± 0,25 dB at 1 + α ≤ -21 dB ≥2 ≤ -40 dB H(f) in-band ripple rm < 0.5 dB rm Nyquist ripple rN .< 0.5 dB | (f - fc ) / fN | 0 dB -3dB rN out-of-band rejection -21 dB > 40dB -40 dB 1-α 1 1+α 2 Figure 8: QPSK Downstream Transmitter Power Spectrum ETSI 21 ETSI EN 301 199 V1.2.1 (1999-06) QPSK systems require the use of differential encoding and corresponding differential detection. This is a result of the receivers having no method of determining if a recovered reference is a sine reference or a cosine reference. In addition, the polarity of the recovered reference is uncertain. Differential encoding transmits the information in encoded phase differences between the two successive signals. The modulator processes the digital binary symbols to achieve differential encoding and then transmits the absolute phases. The differential encoding is implemented at the digital level. 5.2.1.4 Randomizer (Downstream OOB) After addition of the FEC bytes (see subclause 5.3.1), all of the 3,088 Mbit/s data is passed through a six register linear feedback shift register (LFSR) randomizer to ensure a random distribution of ones and zeroes. The output of the randomizer shall be the quotient of the input data multiplied by x and then divided by the generator polynomial x + x + 1. Byte/serial 6 6 5 conversion shall be MSB first. A complementary self-synchronizing de-randomizer is used in the receiver to recover the data. Serial Input Serial Output Figure 9: Example Randomizer Serial Input Serial Output Figure 10: Example De-randomizer 5.2.1.5 Bit Rate (Downstream OOB) The bit rate shall be 3,088 Mbit/s. The support of 3,088 Mbit/s is mandatory for both INA and NIU. Symbol rate accuracy should be within ± 50 ppm. 5.2.1.6 Receiver Power Level (Downstream OOB) (informative) The receiver power level shall be in the range 42 to 75 dBµV (RMS) (75 Ω) at its input. ETSI 22 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.1.7 Summary (Downstream OOB) Transmission Rate 3,088 Mbit/s for Grade B (mandatory for INA and NIU) Modulation Differentially encoded QPSK. Transmit Filtering Filtering is alpha = 0,30 square root raised cosine Channel Spacing 2 MHz for Grade B Frequency Step Size 250 kHz (centre frequency granularity) Randomization After addition of the FEC bytes, all of the 3,088 Mbit/s data is passed through a six register linear feedback shift register (LFSR) randomizer to ensure a random distribution of ones and zeroes. The generating polynomial is: x 6 + x 5 + 1. Byte/serial conversion shall be MSB first. A complementary self-synchronizing de-randomizer is used in the receiver to recover the data. Differential Encoding The differential encoder shall accept bits A, B in sequence, and generate phase changes as follows: A B Phase Change 0 0 none 0 1 +90° 1 1 180° 1 0 -90° In serial mode, A arrives first. System Phase Noise -41 dBc/Hz at 1 kHz max.: ( phase noise -71 dBc/Hz at 10 kHz includes both IF and RF -92 dBc/Hz at 100 kHz parts). Signal Constellation The outputs I, Q from the differential encoder map to the phase states as in Figure 11. Q 01 11 I 00 10 Figure 11: QPSK Constellation IF Frequency Range 950 to 2 150 MHz or 70 to 130 MHz recommended but not mandatory 70 to (informative) 130 MHz and/or 300 to 862 MHz Symbol Rate Accuracy ± 50 ppm Carrier Suppression > 30 dB I/Q Amplitude Imbalance < 1,0 dB I/Q Phase Imbalance < 2,0° Receive Power Level at 42 to 75 dBµV (RMS) (75 Ω) the NIU input (informative) Transmit Spectral Mask A common mask is given in Table 2 and Figure 8. RF Interface A3 ± 200 kHz Frequency uncertainty IF interface A4 frequency ± 5 MHz uncertainty 5.2.1.8 Bit Error Rate Downstream OOB (Informative) To be defined. ETSI 23 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.2 Forward Interaction Path (Downstream IB) The IB Forward Interaction Path shall use a MPEG-2 TS stream with a modulated QPSK channel as defined by EN 300 421 [4]. Frequency range, channel spacing, and other lower physical layer parameters should follow that specification. The accuracy of the downstream RF frequency shall be better than ± 5 MHz. 5.2.3 Return Interaction Path (Upstream) 5.2.3.1 Frequency Range (Upstream) See subclause 5.1.2. 5.2.3.2 Modulation and Mapping (Upstream) The unique word (0X 00 FC FC F3, see subclause 5.3.3 for upstream framing) is not differentially encoded, the outputs I, Q map to the phase states as in Figure 12. Q 01 11 I 00 10 Figure 12: Mapping for the QPSK constellation (upstream) For the remainder of the packet, the differential encoder shall accept bits A, B in sequence, and generate phase changes as follows. It starts with the first information digit and is initialized with the last digit of the unique word, i.e. (A,B = 0,1) since conversion is made MSB first. Table 3: Phase Changes Corresponding to Bits A, B A B Phase Change 0 0 none 0 1 +90° 1 1 180° 1 0 -90° Phase changes correspond to the following formulas (assuming I and Q are mapped to the constellation as for the unique word):  Ak = ( Ik −1 ⊕ Qk −1 ) × (Qk −1 ⊕ Qk ) + ( Ik ⊕ Qk −1 ) × ( Ik ⊕ Ik −1 )  ,  Bk = ( Ik −1 ⊕ Qk −1 ) × ( Ik −1 ⊕ Ik ) + ( Ik −1 ⊕ Qk ) × (Qk ⊕ Qk −1 ) where k is the time index. I/Q amplitude imbalance shall be less than 1,0 dB, and phase imbalance less than 2,0°. ETSI 24 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.3.3 Shaping Filter (Upstream) The time-domain response of a square-root raised-cosine pulse with excess bandwidth parameter α is given by: πt 4 αt πt sin[ (1 − α )] + cos[ (1 + α )] g( t ) = T T T πt 4 αt 2 [1 − ( ) ] T T where T is the symbol period. The output signal shall be defined as: S ( t ) = ∑ [ I n × g ( t − n T ) × c o s ( 2 π f c t ) − Q n × g ( t − n T ) × s in ( 2 π f c t ) ] n with In and Qn equal to ± 1, independently from each other, and fc the QPSK modulator's carrier frequency. The QPSK modulator divides the incoming bit stream so that bits are sent alternately to the in-phase modulator I and the out-of-phase modulator Q. These same bit streams appear at the output of the respective phase detectors in the demodulator where they are interleaved back into a serial bit stream. The QPSK signal parameters are: RF bandwidth BW = (fb / 2) * (1 + α ) Occupied RF Spectrum [fc - BW/2, fc + BW/2] Symbol Rate fs = fb / 2 Nyquist Frequency fN = fs / 2 with fb = bit rate, fc = carrier frequency and α = excess bandwidth. For all bit rates: 3,088 Mbit/s (Grade C) and 6,176 Mbit/s (Grade D), the Power Spectrum at the QPSK transmitter shall comply to the Power Spectrum Mask given in Table 4 and Figure 13. The Power Spectrum Mask shall be applied symmetrically around the carrier frequency. Table 4: QPSK Upstream Transmitter Power Spectrum | ( f - fc ) / fN | Power Spectrum ≤1-α 0 ± 0,25 dB at 1 -3 ± 0,25 dB at 1 + α ≤ -21 dB ≥2 ≤ -40 dB ETSI 25 ETSI EN 301 199 V1.2.1 (1999-06) H(f) in-band ripple rm < 0.5 dB rm Nyquist ripple rN .< 0.5 dB | (f - fc ) / fN | 0 dB -3dB rN out-of-band rejection -21 dB > 40dB -40 dB 1-α 1 1+α 2 Figure 13: QPSK Upstream Transmitter Power Spectrum The specifications which shall apply to HtmlResAnchor QPSK modulation for the upstream channel are given in Table 4. 5.2.3.4 Randomizer (Upstream) The unique word shall be sent in clear (see subclause 5.3.3). After addition of the FEC bytes, randomization shall apply only to the payload area and FEC bytes, with the randomizer performing modulo-2 addition of the data with a pseudo-random sequence. The generating polynomial is x + x + 1 with seed all ones. We assume the first value coming out of the pseudo- 6 5 random generator taken into account is 0. Byte/serial conversion shall be MSB first. The binary sequence generated by the shift register starts with 00000100... The first "0" is to be added in the first bit after the unique word. A complementary non self-synchronizing de-randomizer is used in the receiver to recover the data. The de-randomizer shall be enabled after detection of the unique word. Figure 14: Randomizer 5.2.3.5 Bit Rate (Upstream) Two grades of modulation transmission rate are specified; they are called C and D for compatibility with ETS 300 800 [2]. Table 5: Upstream bit-rates for modulation grades C and D Grade Rate C 3,088 Mbit/s (mandatory for INA and NIU) D 6,176 Mbit/s (optional for INA and NIU) The support of 3,088 Mbit/s is mandatory, of other rates is optional for both INA and NIU. Symbol rate accuracy should be within ± 50 ppm. ETSI 26 ETSI EN 301 199 V1.2.1 (1999-06) For grade C, the rate is 6 000 slots/s. For grade D, the rate is 12 000 slots/s. 5.2.3.6 Transmit Power Level (Upstream) (informative) At the output, the transmit power level shall be in the range 85 to 113 dBµV (RMS) (75 Ω). This power shall be adjustable by steps of 0,5 dB (nominally) by MAC messages coming from the INA. Measured at the INA, the US power accuracy shall be better or equal to ± 1,5 dB. 5.2.3.7 Upstream Burst Power and Timing Profiles Because of the symbol shaping filter that spreads the symbol duration over Ts = 1/symbol_rate, a burst has a ramp up (before the first symbol) and a ramp down (after the last symbol) as shown Figure 15. first last symbol symbol ramp up ramp down ... start of burst time reference Figure 15: Burst Ramp Up and Down The ramps up and down of consecutive bursts can overlap. The ramps shall be minimum 3 symbols long. When the transmitter is idle the upstream power level attenuation shall be more than 60 dB (relative to the nominal burst power output level), over the entire power output. A terminal is considered to be idle if it is 3 slots before an imminent transmission or 3 slots after its most recent transmission. 4 symbols before the first symbol of a burst and 4 symbols after the last symbol, the upstream power level attenuation shall be more than 30 dB (relative to the nominal burst power output level), over the entire power output range. After ranging and propagation delay compensation, the NIU/STB US timing accuracy shall be better than or equal to ± 5/8 th of a symbol (Upstream rate). The time ranging accuracy provided by the MAC messages coming from the INA shall be better than or equal to ± 1/8 th of a symbol (Upstream rate). The NIU messages shall then arrived at the INA in a window of ± 0,75 symbols (Upstream transmission bit rate). 5.2.3.8 Interference (Spurious) Suppression The noise and the spurious power at the output of the transmitting (upstream) device may not exceed the levels as shown in Table 6 below. The measurement bandwidth is equal to the symbol rate. Table 6: Interference Spurious Suppression Transmitting Between bursts burst In band n.a. - 60 dBc (see notes 1 and 2) Adjacent band upstream - 40 dBc - 70 dBc (see notes 1 and 2) NOTE 1: dBc is based on the carrier level during the burst. NOTE 2: The additional suppression of 30 dB for inter burst is based on the connection max. 1 000 NIU's per INA. ETSI 27 ETSI EN 301 199 V1.2.1 (1999-06) 5.2.3.9 Summary (Upstream) Table 7: Summary (Upstream) Upstream Transmission Two grades of modulation transmission bit rate are specified: Bit Rate Grade Rate C 3,088 Mbit/s (mandatory for INA and NIU) D 6,176 Mbit/s (optional for INA and NIU) The support of 3,088 Mbit/s is mandatory, of other rates is optional for both INA and NIU. Modulation Differentially encoded QPSK Transmit Filtering alpha = 0,30 square root raised cosine Channel Spacing 2 MHz for Grade C (3,088 Mbit/s) 4 MHz for Grade D (6,176 Mbit/s) Frequency Step Size 50 kHz Randomization The unique word shall be sent in the clear. After addition of the FEC bytes, randomization shall apply only to the payload area and FEC bytes, with the randomizer performing modulo-2 addition of the data with a pseudo-random sequence. The generating polynomial is x + x + 1 with seed all ones. 6 5 Byte/serial conversion shall be MSB first. A complementary non self-synchronizing de-randomizer is used in the receiver to recover the data. The de-randomizer shall be enabled after detection of the unique word. Differential Encoding The differential encoder shall accept bits A, B in sequence, and generate phase changes as follows. In serial mode, A arrives first. A B Phase Change 0 0 none 0 1 +90° 1 1 180° 1 0 -90° Signal Constellation The outputs I, Q from the differential encoder map to the phase states as in (see note) Figure 16. Q 01 11 I 00 10 Figure 16: Burst QPSK Constellation IF Frequency Range 5 to 65 MHz or 400 to 700 MHz (informative) IF Frequency Stability ± 50 ppm measured at the upper limit of the frequency range Symbol Rate Accuracy ± 50 ppm Transmit Spectral Mask A common mask is given in Table 4 and Figure 13. Carrier Suppression > 30 dB when Transmitter Active ETSI 28 ETSI EN 301 199 V1.2.1 (1999-06) Burst Power Profile Upstream power level attenuation shall be more than 60 dB relative to the nominal burst power output level over the entire power output range and 30 dB right after or before transmission. Idle Transmitter Definition: A terminal is considered to be idle if it is 3 slots before an imminent transmission or 3 slots after its most recent transmission. I/Q Amplitude Imbalance < 1,0 dB I/Q Phase Imbalance < 2,0° Transmit Power Level at 85 to 113 dBµV (RMS) (75 Ω) the modulator output (upstream) (informative) RF interface B3 ± 100 kHz frequency accuracy IF interface B1 frequency ± 200 kHz accuracy NOTE: The unique word ( 0x 00 FC FC F3) does not go through differential encoding. 5.2.3.10 Packet Loss Upstream (Informative) To be defined. 5.2.3.11 Maximum Delay This specification has been designed to support round trip delays of up to 800 µs, which corresponds to a distance of approximately 80 km. Larger delays than this may be accommodated, with judicious use of the specification. 5.3 Framing 5.3.1 Forward Interaction Path (Downstream OOB) 5.3.1.1 Signalling Link Extended Superframe Framing Format The Signalling Link Extended Superframe (SL-ESF) frame structure is shown in Figure 17. The bitstream is partitioned into 4 632-bit Extended Superframes. Each Extended Superframe consists of 24 × 193-bit frames. Each frame consists of 1 overhead (OH) bit and 24 bytes (192 bits) of payload. ETSI 29 ETSI EN 301 199 V1.2.1 (1999-06) 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 24 Frames 24 Frames x 193 bits = 4 632 bits OH Payload 1 192 bits Figure 17: SL-ESF Frame Structure 5.3.1.2 Frame overhead There are 24 frame overhead bits in the Extended Superframe which are divided into Extended Superframe Frame Alignment Signal (F1-F6), Cyclic Redundancy Check (C1-C6), and M-bit Data Link (M1-M12) as shown in Table 8. Bit number 0 is received first. Table 8: Frame overhead Frame Number Bit Number Overhead Bit Data (192 bits) 1 0 M1 2 193 C1 3 386 M2 4 579 F1 = 0 5 772 M3 6 965 C2 7 1 158 M4 8 1 351 F2 = 0 9 1 544 M5 10 1 737 C3 11 1 930 M6 12 2 123 F3 = 1 13 2 316 M7 14 2 509 C4 15 2 702 M8 16 2 895 F4 = 0 17 3 088 M9 18 3 281 C5 19 3 474 M10 20 3 667 F5 = 1 21 3 860 M11 22 4 053 C6 23 4 246 M12 24 4 439 F6 = 1 FAS: Frame Alignment Signal (F1 - F6) DL: Mbit Data Link (M1 - M12) CRC: Cyclic Redundancy Check (C1 - C6) ETSI 30 ETSI EN 301 199 V1.2.1 (1999-06) ESF Frame Alignment Signal The ESF Frame Alignment Signal (FAS) is used to locate all 24 frames and overhead bit positions. The bit values of the FAS are defined as follows: F1 = 0, F2 = 0, F3 = 1, F4 = 0, F5 = 1, F6 = 1. ESF Cyclic Redundancy Check The Cyclic Redundancy Check field contains the CRC-6 check bits calculated over the previous Extended Superframe (CRC Message block [CMB] size = 4 632 bits). Before calculation, all 24 frame overhead bits are equal to "1". All information in the other bit positions is unchanged. The check bit sequence C1-C6 is the remainder after multiplication by x6 and then division by the generator polynomial x6 + x + 1 of the CMB. C1 is the most significant bit of the remainder. The initial remainder value is preset to all zeros. ESF Mbit Data Link The M-bits in the SL-ESF serve for slot timing assignment (see subclause 5.4). 5.3.1.3 Payload Structure The SL-ESF frame payload structure provides a known container for defining the location of the ATM cells and the corresponding Reed Solomon parity values. The SL-ESF payload structure is shown in Table 9. When the INA has no data or MAC messages to send on the downstream OOB channel, it will send Idle ATM Cells as specified in [1], where the content of the Idle ATM Cell has been specified as: 0x00, 0x00, 0x00, 0x01, 0x52 (Idle ATM Cell header) 0x6A, 0x6A, ..., 0x6A (48 data bytes payload) Table 9: ESF Payload structure 2 53 2 1 R1a R1b ATM Cell RS parity 2 R1c R2a R2 b 3 R2c R3a 4 R3b R3c R4 a 5 R4b R4c 6 R5a R5b R5 c 7 R6a R6b 8 R6c R7a R7 b 9 R7c R8a 10 R8b R8c T T The SL-ESF payload structure consists of 5 rows of 57 bytes each, 4 rows of 58 bytes each which includes 1 byte trailer, and 1 row of 59 bytes, which includes a 2 byte trailer. The relative ordering of data between Table 9 and Table 8, is such that reading Table 9 from left to right, and then top to bottom, corresponds to reading Table 8 from top to bottom. The most significant bit of byte R1a in Table 9, corresponds to Bit Number 1 in Table 8. The various SL-ESF payload fields are described below. Define the downstream time-ticks Tdn and the upstream time-ticks Tun as follows: The downstream channel is divided into 3 ms periods separated by downstream time-ticks Tdn and the upstream channel is divided into 3 ms periods separated by upstream time ticks Tun. ETSI 31 ETSI EN 301 199 V1.2.1 (1999-06) Then the time difference, Tun-Tdn, is called the Absolute_Time_Offset: Absolute_Time_Offset = Tun-Tdn. New Absolute_Time_Offset = current Absolute_Time_Offset - Time_Offset_Value. (Time_Offset_Value is defined in subclause 5.5.4.3). Before the NIU is going through the sign-on procedure for the first time, the current Absolute_Time_Offset is set according to the value passed in the Default Configuration message (taking into account the timing accuracy). Time Offset Value is one field of the "Ranging and Power Calibration Message". The NIU shall use the following definitions for using the R-bytes: The boundary information contained in the downstream period that starts by downstream time-tick Tdn relates to the slots in the upstream period that starts at upstream time-tick Tun + 1. This upstream period is also called the "next" one. The reception information contained in the downstream period that starts by downstream time-tick Tdn relates to the slots in the upstream period that starts at upstream time-tick Tun - 2. This upstream period is also called the "second previous" one. ATM Cell Structure The format for each ATM cell structure is shown in Figure 18. This structure and field coding shall be consistent with the structure and coding given in ITU-T Recommendation I.361 [7] for ATM UNI. 40 bits 384 bits Header Information Payload 53 bytes Figure 18: ATM cell format The entire header (including the HEC byte) shall be protected by the Header Error Control (HEC) sequence. The HEC code shall be contained in the last byte of the ATM header. The HEC sequence shall be capable of: - single-bit error correction; - multiple-bit error detection. Error detection in the ATM header shall be implemented as defined in [1]. The HEC byte shall be generated as described in [1], including the recommended modulo-2 addition (XOR) of the pattern 01010101b to the HEC bits. The generator polynomial coefficient set used and the HEC sequence generation procedure shall be in accordance with [1]. Channel coding and interleaving Reed-Solomon encoding with t = 1 shall be performed on each ATM cell. This means that 1 erroneous byte per ATM cell can be corrected. This process adds 2 parity bytes to the ATM cell to give a codeword of (55,53). The Reed-Solomon code shall have the following generator polynomials: Code Generator Polynomial: g(x) = (x + µ0)( x + µ1), where µ = 02 hex Field Generator Polynomial: p(x) = x8 + x4 + x3 + x2 + 1 ETSI 32 ETSI EN 301 199 V1.2.1 (1999-06) The shortened Reed-Solomon Code shall be implemented by appending 200 bytes, all set to zero, before the information bytes at the input of a (255,253) encoder; after the coding procedure these bytes are discarded. Convolutional interleaving shall be applied to the ATM cells contained in the SL-ESF. The Rxa - Rxc bytes and the two T bytes shall not be included in the interleaving process. Convolutional interleaving is applied by interleaving 5 lines of 55 bytes. Following the scheme of Figure 19, convolutional interleaving shall be applied to the error protected packets. The convolutional interleaving process shall be based on the Forney approach, which is compatible with the Ramsey type III approach, with I = 5. The Interleaved frame shall be composed of overlapping error protected packets and a group of 10 packets shall be delimited by the start of the SL-ESF. The interleaver is composed of I branches, cyclically connected to the input byte-stream by the input switch. Each branch shall be a First In First Out (FIFO) shift register, with depth (M*j) cells (where M = N/I, N = 55 = error protected frame length, I = interleaving depth, j = branch index). The input and output switches shall be synchronized. Each cell of the FIFO shall contain one byte. For synchronization purposes, the first byte of each error protected packet shall be always routed into the branch "0" of the interleaver (corresponding to a null delay). The third byte of the SL-ESF payload (the byte immediately following R1b) shall be aligned to the first byte of an error protected packet. The de-interleaver is similar, in principle, to the interleaver, but the branch indexes are reversed (i.e. branch 0 corresponds to the largest delay). The de-interleaver synchronization is achieved by routing the third data byte of the SL-ESF into the "0" branch. 0 0 M M M M 0 1 M M M M 1 IN OUT 2 M M M M 2 3 M M M CHANNEL M 3 4 M M M M 0 4 Figure 19: Interleaver and De-interleaver structures Reception indicator fields and slot boundary fields A downstream channel can control up to 8 upstream channels and contains control information for each of its associated upstream channels. This information is contained within structures known as MAC Flags. A set of MAC Flags is represented by either 24 bits (denoted b0...b23) or by 3 bytes (denoted Rxa, Rxb and Rxc): Rxa = (b0...b7) = (msb...lsb) Rxb = (b8...b15) = (msb...lsb) Rxc = (b16...b23) = (msb...lsb) One or more consecutive MAC flags are associated to one upstream channel. This link is done in the MAC messages Default Configuration Message, Connect Message, Reprovision Message and Transmission Control Message. To the upstream channel "c" (parameter Service_Channel or Upstream_Channel_Number or New_Upstream_Channel_Number of the MAC messages mentioned above) are associated the MAC flags "x" and the following as described below. "x" corresponds to the parameter MAC_Flag_Set of the previous MAC messages. It is a 5-bit field and can take the values 1...16. Values 0 and 17...31 are invalid. ETSI 33 ETSI EN 301 199 V1.2.1 (1999-06) In the OOB downstream case, each HtmlResAnchor SL-ESF frame structure contains eight sets of MAC Flags represented by Rxa, Rxb and Rxc, where x is replaced by the numbers 1...8 providing 8 sets of MACFlags. In the case of a 3,088 Mbit/s downstream bit rate, two SL-ESFframes A and B occur during a 3 ms interval, providing 16 sets of MAC Flags. The second set of MAC Flags (contained in SL-ESF B) are denoted by Rxa, Rxb and Rxc, where x is replaced by the numbers 9 through 16. In case of a 3,088 Mbit/s upstream channel, two sets of MAC Flags are required. In this case, the MAC_Flag_Set parameter represents the first of two successively assigned MAC Flag sets (Rxa-Rxc,Rya-Ryc with y = (x + 1) belongs to [1, 15] for 3,088 Mbit/s DS. In case of a 6,176 Mbit/s upstream channel, four sets of MAC Flags are required. In this case, the MAC_Flag_Set parameter represents the first of four successively assigned MAC Flag sets (Rxa-Rxc,Rua-Ruc,Rva-Rvc,Rwa-Rwc with u = (x + 1), v = (x + 2), w =(x + 3), with x belongs to [1, 13] for 3,088 Mbit/s DS. In particular, if one downstream OOB 3,088 Mbit/s channel controls 6,176 Mbit/s upstream channels, at most 4 upstream channels can be controlled, due to the number of available MAC Flags. The bits b0 to b23 are defined as follows: b0 = ranging slot indicator for next 3 ms period (msb) b1-b6 = slot boundary definition field for next 3 ms period b7 = slot 1 reception indicator (as shown in Table 13) b8 = slot 2 reception indicator (as shown in Table 13) b9 = slot 3 reception indicator (as shown in Table 13) b10 = slot 4 reception indicator (as shown in Table 13) b11 = slot 5 reception indicator (as shown in Table 13) b12 = slot 6 reception indicator (as shown in Table 13) b13 = slot 7 reception indicator (as shown in Table 13) b14 = slot 8 reception indicator (as shown in Table 13) b15 = slot 9 reception indicator (as shown in Table 13) b16-17 = reservation control for next 3 ms period b18-b23 = CRC 6 parity (see definition in SL-ESF section) When the upstream transmission bit rate is 3,088 Mbit/s, the 9 slots of this field and the 9 slots of the following field are valid: two consecutive Slot Configuration fields are then used. The definition of the first Slot Configuration field is unchanged. The definition of the second Slot Configuration field extends the boundary definition to cover upstream slots 10 through 18, and the reception indicators to cover upstream slots 10 through 18. When the upstream transmission bit rate is 6,176 Mbit/s, four consecutive Slot Configuration fields are then used. The definition of the first Slot Configuration field is unchanged. The definition of the second Slot Configuration field extends the boundary definition to cover upstream slots 10 through 18, and the reception indicators to cover upstream slots 10 through 18. The definition of the third Slot Configuration field extends the boundary definition to cover upstream slots 19 through 27, and the reception indicators to cover upstream slots 19 through 27. The definition of the fourth Slot Configuration field extends the boundary definition to cover upstream slots 28 through 36, and the reception indicators to cover upstream slots 28 through 36. Ranging Slot Indicator (b0) - When this bit is active (b0 = 1), the first three slots of upstream channel "x" which correspond to the occurrence of the next superframe of the related downstream channel are designated as ranging slots. A ranging message may be transmitted in the second ranging slot according to the algorithm defined for ranging, and the first and third ranging slots may not be used for transmission (guard band for ranging operations). ETSI 34 ETSI EN 301 199 V1.2.1 (1999-06) Slot Boundary Definition field (b1-b6) - Slot types are assigned to upstream slots using bits b0-b6. The slots are grouped into regions among "spans" of 2*9 slots (two spans of 9 slots are used for 3,088 Mbit/s), or 4*9 slots (four spans of 9 slots are used for 6,176 Mbit/s), such that slots of a similar type are contained within the same region. The order of the regions is Ranging slot, Contention based slots, Reserved slots and Fixed rate based slots. If a ranging slot is available within a "span", it will consist of the first three slot times in the "span", assuming b1-b6 are not in the range 55-63 (see Table 12). A ranging slot is indicated by b0 = 1. The boundaries between the remaining regions of the "spans" are defined by b1-b6. The boundaries are defined as shown in Table 10. Table 10: Slot Boundary Definition field (b1-b6) Boundary 0 slot 1 Boundary 1 slot 2 Boundary 2 slot 3 Boundary 3 slot 4 Boundary 4 slot 5 Boundary 5 slot 6 Boundary 6 slot 7 Boundary 7 slot 8 Boundary 8 slot 9 Boundary 9 The boundary positions are defined by b1-b6 as shown in Table 11. Table 11: Boundary positions (b1-b6) (note 1) 0 1 2 3 4 5 6 7 8 9 (note 2) 0 (note 3) 0 1 2 3 4 5 6 7 8 9 1 (note 3) 10 11 12 13 14 15 16 17 18 2 (note 3) 19 20 21 22 23 24 25 26 3 27 28 29 30 31 32 33 4 34 35 36 37 38 39 5 40 41 42 43 44 6 45 46 47 48 7 49 50 51 8 52 53 9 54 NOTE 1: row = Contention based / Reserved region boundary. NOTE 2: column = Reserved packet /Fixed rate based region boundary. NOTE 3: When the ranging control slot indicator (b0) is set to "1", the values in rows 0 to 2 are illegal values, and values in row 3 means that there are no contention slots, because slots 1-3 are defined as ranging control slots. Example: b0 = 0, b1-b6 = 22: Contention (1-2), reserved (3-5), Fixed rate (6-9) The remaining values of the Slot Boundary Definition Field are provided in Table 12. ETSI 35 ETSI EN 301 199 V1.2.1 (1999-06) Table 12: Slot Boundary Definition Field b1-b6 ranging control contention slots reservation fixed rate value slots slots slots 55 1-6 7-9 - - 56 1-6 7-8 - 9 57 1-6 7 8-9 - 58 1-6 7 8 9 59 1-6 7 - 8-9 60 1-6 - 7-8 9 61 1-6 - 7 8-9 62 1-6 - - 7-9 63 1-9 - - - NOTE 1: For b1-b6 = 55 - 63, b0 shall be set to 1. Note that for b1-b6 between 55 and 62, two ranging slots are provided (2 and 5). For b1-b6 = 63, three ranging slots are provided (2, 5, and 8). The values in the above tables are derived from b1-b6 in the following manner: b1 + (b2 × 2) + (b3 × 4) + (b4 × 8) + (b5 × 16) + (b6 × 32) Warning: This formula indicates that b6 is considered as msb of b1-b6 word, whereas b0 is msb of the entire word b0-b23. Although this "looks" inconsistent, it has not been changed for the purpose of compatibility with the DAVIC standard. NOTE 2: If slot boundary fields change while some NIUs have already been allocated slots in the reservation slots area, these NIUs are responsible of updating the list of physical slots. Specifically, slots are assigned by MAC Reservation Grant messages, which contain a Reference slot that does not depend on the slot boundary fields and a Grant_slot_count which corresponds to the number of slots assigned within the reservation slots boundary field. If the field changes, the list of physical slots on which the NIU can transmit automatically changes accordingly. Slot Reception Indicators (b7 - b15) - When a slot reception indicator is active ("1"), this indicates that a cell was received without collision. The relationship between a given US slot and its indicator is shown in Table 13. When the indicator is inactive ("0"), this indicates that either a collision was detected or no cell was received in the corresponding upstream slot. Slot reception indicators lead to the retransmission procedure only when contention access is used as described in subclause 5.5.2.4. ETSI 36 ETSI EN 301 199 V1.2.1 (1999-06) Table 13: Relationship of US slot to DS Indicator at the INA 1,544 Mbit/s Downstream 3,088 Mbit/s Downstream 256 kbit/s NONAPPLICABLE NON APPLICABLE Upstream 1,544 Mbit/s NON APPLICABLE NON APPLICABLE Upstream 1 Frame 3,088 Mbit/s NON APPLICABLE Upstream DS I I US 18 slots 6,176 Mbit/s NON APPLICABLE Upstream 1 Frame DS I I US 36 slots NOTE 1: "I" indicates the downstream frame(s) in which Indicators (contained within the MAC Flag Sets) are sent. These indicators control the upstream slots in the shaded area. NOTE 2: In the 3,088 downstream, two successive frames contain HtmlResAnchor MAC Flag Sets 1...16. NOTE 3: Two successive MAC Flag Sets are used to control the 18 slots of a 3,088 upstream channel. NOTE 4: Four successive MAC Flag Sets are used to control the 36 slots of a 6,176 upstream channel. In this case you can control max. 4 upstreams using the 3,088 downstream. NOTE 5: Note that this table refers to the position of US slots with respect to the positions of DS superframes at the INA receiver. NIUs should have their Time_Offset_Value of transmission set such that this table applies. Reservation Control (b16-b17) - When the reservation control field has the value of 0, no reservation attempts are allowed to be transmitted on the corresponding QPSK upstream channel during the slot positions associated with the next 3 ms period. When the reservation control field has the value of 1, reservation attempts can be made. The values 2 and 3 are reserved. A reservation attempt corresponds to sending a MAC Reservation Request message (see MAC section). b16 is msb. CRC 6 Parity (b18-b23) - This field contain a CRC 6 parity value calculated over the previous 18 bits. The CRC 6 parity value is described in the SL-ESF frame format subclause 5.3.1.2, b18 is msb. In the case where there is more than one OOB DS QPSK channel related to an upstream QPSK channel, the SL-ESF overhead bits and the payload R-bytes shall be identical in those OOB DS channels, with the exception of the overhead CRC (C1-C6) bits, which are specific to each of those OOB DS channels. Such related DS channels shall be synchronized (transmitted synchronously). This scenario applies for example when a lot more bandwidth is needed for DS information than US information. An NIU is but not required to have more than one QPSK tuner. The MAC messages that are required to perform the MAC functions for the upstream channel shall be transmitted on each of its related OOB DS channels. Trailer bytes These bytes are not used. They are equal to 0. ETSI 37 ETSI EN 301 199 V1.2.1 (1999-06) 5.3.2 Forward Interaction Path (Downstream IB) 5.3.2.1 IB Signalling MPEG2-TS Format (MAC Control Message) The structure that is utilized when the downstream QPSK IB channel is carrying MPEG2-TS packets is shown in Figure 20 MSBs of each field are transmitted first. 4 3 2 3 26 26 40 40 40 4 MPEG Upstream Slot MAC Flag MAC Ext. MAC MAC MAC rsrvc Header Marker Numbr Control Flags Flags msg. msg. msg. Figure 20: Frame structure (MPEG-2 TS format) where: MPEG Header is the 4 byte MPEG-2 Transport Stream Header as defined in ISO 13818-1 [9] with a specific PID designated for MAC messages. This PID is 0x1C. The transport_scrambling_control field of the MPEG header shall be set to "00". Upstream Marker is a 24-bit field which provides upstream QPSK synchronization information. (As mentioned in subclause 5.1.4, at least one packet with synchronization information shall be sent in every period of 3 ms). The definition of the field is as follows: bit 0: upstream marker enable (msb) When this field has the value "1", the slot marker pointer is valid. When this field has the value "0", the slot marker pointer is not valid. bit 1-3: MAC Message Framing Bit 1 relates to the first MAC message slot within the MPEG frame, bit 2 to the second, and bit 3 to the last slot. The meaning of each bit is: • 0: a MAC message terminates in this slot. • 1: a MAC message continues from this slot into the next, or the slot is unused, in which case the first two bytes of the slot are 0x0000. bit 4-7: reserved bit 8-23: upstream slot marker pointer The slot marker pointer is a 16-bit unsigned integer which indicates half the number of downstream "symbol" clocks between the next Sync byte and the next 3 ms time marker. Bit 23 is to be considered as the most significant bit of this field. Slot Number is a 16-bit field which is defined as follows: (As mentioned in subclause 5.1.4, at least one packet with synchronization information shall be sent in every period of 3 ms). bit 0: slot position register enable (msb) When this field has the value "1", the slot position register is valid. When this field has the value "0", the slot position register is not valid. bit 1-3: reserved bit 4 is set to the value "1". This bit is equivalent to M12 in the case of OOB downstream. bit 5: odd parity This bit provides odd parity for upstream slot position register. This bit is equivalent to M11 in the case of OOB downstream. ETSI 38 ETSI EN 301 199 V1.2.1 (1999-06) bits 6-15: upstream slot position register The upstream slot position register is a 10-bit counter which counts from 0 to n with bit 6 the msb. These bits are equivalent to M10-M1 in the case of OOB downstream. (see subclause 5.4 or more information on the functionality of the upstream slot position register) MAC Flag Control is a 24-bit field (b0 (msb),b1, b2...b23) which provides control information which is used in conjunction with the "MAC Flags" and "Extension Flags" fields. The definition of the MAC Flag Control field is as follows: b0-b2 Channel 0 control field b3-b5 Channel 1 control field b6-b8 Channel 2 control field b9-b11 Channel 3 control field b12-b14 Channel 4 control field b15-b17 Channel 5 control field b18-b20 Channel 6 control field b21-b23 Channel 7 control field Each of the above Channel "c" Control Fields is defined as follows: Channel "c" control field (a, b, c) = (bn, bn + 1, bn + 2) where n = 3*c bit a: 0 - MAC Flag Set of channel "c" disabled 1 - MAC Flag Set of channel "c" enabled "MAC Flag Set of Channel "c" enabled" means that the Mac Flags assigned to the upstream channel "c" are valid in this TS packet. The relation between the channel number "c" and the assigned Mac Flag sets is provided in the "Default Configuration", "Connect", "Reprovision" and "Transmission control" messages. In case of a 3,088 Mbit/s upstream channel, two sets of HtmlResAnchor MAC Flags are required. In this case, the MAC_Flag_Set parameter represents the first of two successively assigned HtmlResAnchor MAC Flag sets. The definition of the second slot configuration field extends the boundary definition to slots 10 through 18, and the reception indicators cover slots 10 through 18. In case of a 6,176 Mbit/s upstream channel, four sets of MAC Flags are required. In this case, the MAC_Flag_Set parameter represents the first of four successively assigned MAC Flag sets. The definition of the second slot configuration field extends the boundary definition to slots 10 through 18, and the reception indicators cover slots 10 through 18. The definition of the third Slot Configuration field extends the boundary definition to cover upstream slots 19 through 27, and the reception indicators to cover upstream slots 19 through 27. The definition of the fourth Slot Configuration field extends the boundary definition to cover upstream slots 28 through 36, and the reception indicators to cover upstream slots 28 through 36. bit b, c: 00 - all flags valid for second previous 3 ms period (out-of-band signalling equivalent) 01 - flags valid for 1st ms of previous 3 ms period 10 - flags valid for 2nd ms of previous 3 ms period 11 - flags valid for 3rd ms of previous 3 ms period ETSI 39 ETSI EN 301 199 V1.2.1 (1999-06) MAC Flags is a 26 byte field containing 8 slot configuration fields (24 bits each) which contain slot configuration information for the related upstream channels followed by two reserved bytes ( The First 3 bytes correspond to MAC Flag Set 1, second 3 bytes to MAC Flag Set 2, etc). The definition of each slot configuration field is defined as follows: b0 ranging control slot indicator for next 3 ms period (msb) b1-b6 slot boundary definition field for next 3 ms period b7 slot 1 reception indicator for [second] previous 3 ms period b8 slot 2 reception indicator for [second] previous 3 ms period b9 slot 3 reception indicator for [second] previous 3 ms period b10 slot 4 reception indicator for [second] previous 3 ms period b11 slot 5 reception indicator for [second] previous 3 ms period b12 slot 6 reception indicator for [second] previous 3 ms period b13 slot 7 reception indicator for [second] previous 3 ms period b14 slot 8 reception indicator for [second] previous 3 ms period b15 slot 9 reception indicator for [second] previous 3 ms period b16-17 reservation control for next 3 ms period b18-b23 CRC 6 parity The slot configuration fields are used in conjunction with the MAC Flag Control field defined above. Note that when the MAC Flag Control field designates that a 1 ms flag update is enabled; (1) the reception indicators refer to the previous 3 ms period (the bracketed term [second] is omitted from the definition), (2) only the reception indicators which relate to slots which occur during the designated 1 ms period are valid, and (3) the ranging control slot indicator, slot boundary definition field, and reservation control field are valid and consistent during each 3 ms period. Extension Flags is a 26 byte field which is used when one or more 3,088 Mbit/s or 6,176 Mbit/s upstream QPSK links are used. The definition of the Extension Flags field is identical to the definition of the MAC Flags field above. The "Extension Flags" field contains the MAC Flags from 9 to 16. The MAC Message field contains a 40 byte message, the general format is defined in subclause 5.5.2.7. reserved field c is a 4 byte field reserved for future use. 5.3.2.2 Frequency of IB Signalling Information IB Downstream Time-Tick Definition In the case of IB, downstream time-tick Tdn is the 3 ms time marker Downstream (defined in subclause 5.4.2). Upstream Marker and Slot Position Register Number The MAC Control Message structures shall be transmitted one time every 3 ms with an enabled slot position register (slot_position_register_enable = 1) and a valid upstream marker (upstream_Marker_enable = 1) (i.e. both are valid in the same packet). MAC Flag Control, MAC Flags & Extension Flags The MAC Control Message structures containing MAC Flag Control, MAC Flags & Extension Flags shall be transmitted so as to the NIU has at least 1 millisecond to process the MAC Flag Information. This information shall be received by the NIU between two downstream time-ticks (see subclause 5.3.1.3). ETSI 40 ETSI EN 301 199 V1.2.1 (1999-06) MAC Messages Additional MAC Control Message structures containing only MAC messages, i.e. with a disabled slot position register (slot_position_register_enable = 0), a disabled upstream marker (upstream_marker_enable = 0) may be transmitted at any time. 5.3.3 Return Interaction Path (Upstream) 5.3.3.1 Slot Format The format of the upstream slot is shown in Figure 21 below. A Unique Word (UW) (4 bytes) provides a burst mode acquisition method. The payload area (53 bytes) contains a single message cell. The RS Parity field (6 bytes) provides t = 3 Reed Solomon protection RS (59,53) over the payload area. The Guard band (1 byte) provides spacing between adjacent packets. 4 bytes 53 bytes 6 bytes 1 byte UW Payload Area RS Parity Guard Band Figure 21: Slot format The structure and field coding of the message cell shall be consistent with the structure and coding given in ITU-T Recommendation I.361 [7] for ATM UNI. Unique Word The unique word is four bytes long: 0X 00 FC FC F3 hex. The unique word for minislots is four bytes: 0X 00 FC FC F3 hex, transmitted in this order. ATM Cell Structure The format for each ATM cell structure is illustrated below. This structure and field coding shall be consistent with the structure and coding given in ITU-T Recommendation I.361 [7] for ATM UNI. 40 bits 384 bits Header Information Payload 53 bytes Figure 22: ATM cell format The entire header (including the HEC byte) shall be protected by the Header Error Control (HEC) sequence. The HEC code shall be contained in the last byte of the ATM header. The HEC sequence shall be capable of: - single-bit error correction; - multiple-bit error detection. ETSI 41 ETSI EN 301 199 V1.2.1 (1999-06) Error detection in the ATM header shall be implemented as defined in [1]. The HEC byte shall be generated as described in [1], including the recommended modulo-2 addition (XOR) of the pattern 01010101b to the HEC bits. The generator polynomial coefficient set used and the HEC sequence generation procedure shall be in accordance with [1]. Channel Coding Reed-Solomon encoding shall be performed on each ATM cell with T = 3. This means that 3 erroneous byte per ATM cell can be corrected. This process adds 6 parity bytes to the ATM cell to give a codeword of (59,53). The shortened Reed-Solomon Code shall be implemented by appending 196 bytes, all set to zero, before the information bytes at the input of a (255,249) encoder; after the coding procedure these bytes are discarded. The Reed-Solomon code shall have the following generator polynomials: Code Generator Polynomial: g(x) = (x + µ0)( x + µ1) (x + µ2) ... ( x + µ5), where µ = 02 hex. Field Generator Polynomial: p(x) = x8 + x4 + x3 + x2 + 1. Guard Band The guard band is 1 byte long (4 QPSK symbols). It provides some extra protection against synchronization errors. For the minislot slot format see subclause 5.6.2. 5.3.4 Minimum Processing Time The NIU has to be able to process the boundary information in the Mac flag sets within 1 millisecond. ETSI 42 ETSI EN 301 199 V1.2.1 (1999-06) 5.4 Slot Timing Assignment 5.4.1 Downstream Slot Position Reference (Downstream OOB) Upstream synchronization is derived from the downstream extended superframe (OOB) by noting the slot positions as shown in Table 14. Table 14: Downstream slot position reference Frame Bit Overhead Slot position Number Number Bit reference 1 0 M1 ♦ Slot Position 1 2 193 C1 3 386 M2 4 579 F1 = 0 5 772 M3 6 965 C2 7 1 158 M4 8 1 351 F2 = 0 9 1 544 M5 ♦ Slot Position 10 1 737 C3 11 1 930 M6 12 2 123 F3 = 1 13 2 316 M7 14 2 509 C4 15 2 702 M8 16 2 895 F4 = 0 17 3 088 M9 ♦ Slot Position 18 3 281 C5 19 3 474 M10 20 3 667 F5 = 1 21 3 860 M11 22 4 053 C6 23 4 246 M12 24 4 439 F6 = 1 For the 3,088 Mbit/s rate downstream, the 3 ms time marker only appears once every two superframes. The M12 bit (see subclause 5.4) is used to differentiate between the two superframes. 5.4.2 Downstream Slot Position Reference (Downstream IB) Upstream synchronization is derived from the Transport Stream by noting the 3 ms time marker Downstream as shown in Figure 23. From the bits of the upstream marker field contained in the MPEG-2 TS packet, the 3 ms time marker is obtained by counting a number of symbol clocks equal to (b23-b8). This marker is equivalent to the first slot position of the superframe for the OOB case. Figure 23: Position of the 3 ms time marker for IB signalling NOTE: The upstream marker pointer gives half the number of baud clocks to count; the baud rate considered is before inner coding and transmission. In order to describe how the US slot position is derived from the location of the DS 3 ms time marker at the NIU, consider the following system diagram. ETSI 43 ETSI EN 301 199 V1.2.1 (1999-06) Headend Delays Data Link Settop Box Delays Delays DATA DS D1 d3 d4 D2 DL+ dL DIA DIB Figure 24: System Model for Timing Analysis The delay between the location of the end of the Upstream Marker and the beginning of the next Sync byte, designated as DS, is a constant value for each bit rate equal to the equivalent time of 197 bytes, or (197 * 8 /x) symbol clocks where: x = 2, for QPSK There will be some processing delay in the Head-end hardware between the location where the Upstream Marker is inserted in the MAC packet and the arrival of the data into the interleaver. This should be a constant delay, D1, which is the same for every incoming byte, including the sync byte following the Upstream Marker. The delay due to the interleaving process in the Head-end is DIA and will be zero for each sync byte. There will be some processing delay in the Head-end hardware between the output of the interleaver and the output of the QPSK IB modulator. This should be a constant delay, D2, for every byte in the outgoing stream. The data link is composed of two delay values, DL, the constant link delay that every STU experiences, and dL, the variable link delay for each STU which is due to the fact that each STU is located at a different distance from the Head-end. This variable link delay is compensated for by the ranging operation. There will be some processing delay in the STU hardware between the input of the QPSK IB demodulator and the input of the de-interleaver. This delay is design dependent, d3, and may be a constant delay or a variable delay for each byte in the data stream. The delay due to the de-interleaving process in the STU is DIB, and will be equal to the entire interleave delay for each sync byte. ETSI 44 ETSI EN 301 199 V1.2.1 (1999-06) The total interleave delay, DI = DIA + DIB will be constant for each byte. The value will be given by: DI = 204 * 8 * (interleave_depth-1) / bit rate. There will be some processing delay in the STU hardware between the output of the de-interleaver and the circuitry that utilizes the Upstream marker and following sync byte for generating the local 3 ms time marker. This delay, which includes FEC, is design dependent, d4, and may be a constant delay or a variable delay for each byte in the data stream. The accumulated delay in the data link is composed of a number of constant terms and three variable terms. The constant terms will be identical for every STU that is utilizing a particular QPSK IB channel for in-band timing and thus becomes a fixed offset between when the counter which is loading the Upstream Marker value and the actual location of the 3 ms time marker at each STU. Each STU is responsible for compensating for the design dependent delays, d3 and d4, before utilizing the Upstream Marker value for generating the 3 ms time marker. The variable link delay, dL, will be compensated for via the ranging algorithm, in the same way as performed when out-of-band signalling is employed. 5.4.3 Upstream Slot Positions Transmission on each QPSK upstream channel is based on dividing access by multiple NIU units by utilizing a negotiated bandwidth allocation slot access method. A slotting methodology allows the transmit slot locations to be synchronized to a common slot position reference, which is provided via the related downstream MAC control channel. Synchronizing the slot locations increases message throughput of the upstream channels since the ATM cells do not overlap during transmission. The slot position reference for upstream slot locations is received via the related downstream MAC control channel by each NIU. Since each NIU receives the downstream slot position reference at a slightly different time, due to propagation delay in the transmission network, slot position ranging is required to align the actual slot locations for each related upstream channel. The upstream slot rates are 12 000 upstream slots/sec when the upstream transmission rate is 6,176 Mbit/s, 6 000 upstream slots/sec when the upstream transmission bit rate is 3,088 Mbit/s. The number of slots available in any one second is given by: number of slots/sec = upstream transmission bit rate / 512 - (extra guardband) where extra guardband may be designated between groups of slots for alignment purposes. The M-bits in the SL-ESF serve two purposes: - to mark the slot positions for the upstream Contention and Reservation and Fixed Rate based signalling links (see subclause 5.4); - to provide slot count information for upstream message bandwidth allocation management in the NIU. M-bits M1, M5, and M9 mark the start of an upstream slot position for upstream message transmission. 5.4.3.1 Rate 256 kbit/s Non applicable. 5.4.3.2 Void 5.4.3.3 Rate 1,544 Mbit/s Non applicable. ETSI 45 ETSI EN 301 199 V1.2.1 (1999-06) 5.4.3.4 Rate 3,088 Mbit/s ← 3 ms time period → s(k-1) k k k k k k k k k k k k k k k k k k s(k+18) + + + + + + + + + + + + + + + + + 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 ‹ ‹ ‹ ‹ ‹ ‹ 3 slot position references (downstream) per 3 ms time period In the case where the downstream OOB rate is 3,088 Mbit/s, there are 6 slot position references downstream during the transmission of 18 upstream packets. In the case of IB downstream, packet « k » is sent when the 3 ms time marker is received. The relationship between the received slot position reference and the actual slot transmit position is given by: slot_transmit_position = slot_position_reference(valid) + slot_position_offset, where only the slot_position_references which cause the upstream_slot_position_counter to be loaded are valid (see subclause 5.4.4), and the slot_position_offset is derived from the Time_Offset_Value provided via the Range_and_Power_Calibration_Message. ← slot_transmit_position slot (j-1) slot (j) Å slot_position_offset Æ ‹ slot position reference (downstream) In the case where the upstream transmission bit rate is 3,088 Mbit/s, the actual slot transmission locations are given by: slot_transmission_location (m) = slot_transmit_position + (m * 512), where m = 0,1,2,3,4,5; is the position of the slot with respect to the slot_transmit_position. This leaves a free time interval (FI = 16 bits)) before the next slot_transmit_position occurs, during which no NIU transmits anything. ←slot_transmit_position ←slot_transmit_position Å loc Å Å loc Å Å Å 0 2 loc 4 loc 1 loc 3 loc 5 previous slot slot 0 slot1 slot 2 slot 3 slot 4 slot 5 F next slot (m=0) (m=1) (m=2) (m=3) (m=4) (m=5) I 512 512 512 512 512 512 1 bits bits bits bits bits bits 6 b i t s ETSI 46 ETSI EN 301 199 V1.2.1 (1999-06) 5.4.3.5 Rate 6,176 Mbit/s ← 3 msec time period → s(k-1) k K K k k k k k k k k k k k k k k k K K k k k k k k k k k k k k k k k k s(k+36) + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + + 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 ‹ ‹ ‹ ‹ 3 slot position references (downstream) per 3 msec time period There are 6 slot position references downstream during the transmission of 36 upstream packets. In the case of IB downstream, packet « k » is sent when the 3 ms time marker is received. The relationship between the received slot position reference and the actual slot transmit position is given by: slot_transmit_position = slot_position_reference(valid) + slot_position_offset, where only the slot_position_references which cause the upstream_slot_position_counter to be loaded are valid (see subclause 5.4.4), and the slot_position_offset is derived from the Time_Offset_Value provided via the Range_and_Power_Calibration_Message. ← slot_transmit_position slot (j-1) slot (j) Å slot_position_offset Æ ‹ slot position reference (downstream) In the case where the upstream transmission bit rate is 6,176 Mbit/s, the actual slot transmission locations are given by: slot_transmission_location (m) = slot_transmit_position + (m * 512), where m = 0,1,2,3,4,5,6,7,8,9,10,11; is the position of the slot with respect to the slot_transmit_position. This leaves a free time interval (FI = 32 bits)) before the next slot_transmit_position occurs, during which no NIU transmits anything. ←slot_transmit_position ←slot_transmit _position Å locÅ Å locÅ Å Å Å locÅ Å locÅ Å loc Å 0 2 loc 4 6 8 10 loc 1 loc 3 loc 5 loc 7 loc 9 loc 11 previous slot 0slot1 slot 2slot 3slot 4slot 5slot 6slot 7slot 8slot 9slot 10slot 11FI next slot slot (m=0) (m=1) (m=2) (m=3) (m=4) (m=5) (m=6) (m=7) (m=8) (m=9) (m=10) (m=11) 512 512 512 512 512 512 512 512 512 512 512 512 32 bits bits bits bits bits bits bits bits bits bits bits bits bit s ETSI 47 ETSI EN 301 199 V1.2.1 (1999-06) 5.4.4 Slot Position Counter The M-bits M10 - M1 are a register, called the upstream slot position register, which counts from 0 to N, incrementing by one every 3 ms, where N is an unsigned integer which indicates slot position cycle size (the value of N is calculated from Service_Channel_Last_Slot sent in the Default Configuration Message and the upstream transmission bit rate of the service channel. For the case of 3,088 Mbit/s the maximum value is imposed to be 8 189, and for the case of 6,176 Mbit/s the maximum value is imposed to be 8 171. The value of N shall be the same for all DS carriers, and N is related to the number of US slots by: Number_of_US_Slots = 3 * m * (N+1), where m is related to US rate as described below. The upstream slot position register indicates the upstream slot positions that will correspond to the next SL-ESF frame. There are 12 upstream slots per ms when the upstream transmission bit rate is 6,176 Mbit/s, 6 upstream slots per ms when the upstream transmission bit rate is 3,088 Mbit/s. The corresponding upstream slot rates are, therefore, 12 000 upstream slots/sec when the upstream transmission bit rate is 6,176 Mbit/s, 6 000 upstream slots/sec when the upstream transmission bit rate is 3,088 Mbit/s. There are 36 upstream minislots per ms when the upstream data rate is 6,176 Mbit/s, there are 18 upstream minislots per ms when the upstream data rate is 3,088 Mbit/s. The corresponding upstream minislot rates are, therefore, 36 000 upstream minislots/sec when the upstream data rate is 6,176 Mbit/s, 18 000 upstream minislots/sec when the upstream data rate is 3,088 Mbit/s. The algorithm to determine the upstream slot position counter value is given below: In the case of OOB downstream, the algorithm to determine the upstream slot position counter value is given below: upstream_slot_position_register = value of M-bits latched at bit_position M11 (M10 - M1) if (upstream_rate == 3,088 Mbit/s) {m = 6;} else if (upstream_rate == 6,188 Mbit/s) {m = 12;} if (bit_position == M1 and previous M12 == 1) {upstream_slot_position_counter = upstream_slot_position_register * 3 * m;} if (bit_position == M5) if (previous M12 == 0) {upstream_slot_position_counter = upstream_slot_position_counter + m;} if (bit_position == M9) if (and previous M12 == 1)) {upstream_slot_position_counter = upstream_slot_position_counter + m;} if (bit_position == M11) {temp_upstream_slot_position_register = (M10, M9, M8, ..., M1);} if ( (bit_position == M12 and M12 == 1) ) {upstream_slot_position_register = temp_upstream_slot_position_register;} where the M-bits will be defined as follows: M1 - M10 = 10-bit ESF counter which counts from 0 to n with M10 the most significant bit (MSB); M11 = odd parity for the ESF counter, i.e., M11 = 1 if the ESF Counter (M1-M10) has an even number of bits set to 1; M12 = 1: ESF counter valid 0; ESF counter not valid ETSI 48 ETSI EN 301 199 V1.2.1 (1999-06) The values assigned to M12 are as follows: 1) The information is always transmitted in pairs of superframe, where superframe-A is the first superframe in the pair, and superframe-B is the second superframe in the pair. In this case, the M12 bit of superframe-A is set to the value "0" and the M12 bit of superframe-B is set to the value "1". 2) When the downstream channel is IB, M12 = 1. In the case of IB downstream, the upstream slot timing should mimic that of the OOB downstream. 5.5 MAC Functionality 5.5.1 MAC Reference Model The scope of this subclause is limited to the definition and specification of the MAC Layer protocol. The detailed operations within the MAC layer are hidden from the above layers. This subclause focuses on the required message flows between the INA and the NIU for Media Access Control. These areas are divided into three categories: Initialization, Provisioning and Sign On Management, Connection Management and Link Management. Higher Layers L Link o Management Initialization, w Sign-On and e Provisioning Connection Data r Management L Management Adaptation MAC a MAC Management Entity Sublayer y e MAC Signaling r P Multicast Address Resolution LLC r o Singlecast Address Resolution t MAC o c o Physical Physical l s IEEE 802 Reference Model Figure 25: MAC Reference Model 5.5.2 MAC Concept 5.5.2.1 Relationship Between Higher Layers and MAC Protocol The goal of the MAC protocol is to provide tools for higher layer protocols in order to transmit and receive data transparently and independently of the physical layer. Higher layer services are provided by the INA to the STU. The INA is thus responsible of indicating the transmission mode and rate to the MAC layer for each type of service. ETSI 49 ETSI EN 301 199 V1.2.1 (1999-06) Specifically, for each connection provided by higher layers on the INA side (VPI/VCI), a connection ID is associated at the MAC layer. The maximum number of simultaneous connections that a NIU should support is defined as follows: Level A: Only one connection at a time can be handled by a NIU. Level B: As many connections as needed, defined dynamically by the INA, following higher layers requests. Note that in this case all connections should be assigned to the same frequency upstream and downstream for implementation reasons. Note however, that bandwidth (time slots) does not need to be assigned immediately by the INA for a given connection. This means that a connection ID may exist at the NIU side without associated slot numbers. The INA is responsible of providing transmission bandwidth to the NIUs when needed by higher layers. However, since the NIU shall transmit all data from the STU, the NIU is also responsible for requesting for more bandwidth if not already provided by the INA. An initial connection is allocated to the STB by the INA, following the successful completion of sign-on at power up. This connection can be used to send data from higher layers leading to further interactive connections. Note that this connection can be associated to a zero transmission rate (no initial bandwidth allocation). 5.5.2.2 Relationship Between Physical Layer and MAC Protocol Up to 8 QPSK Upstream channels can be related to each downstream channel which is designated as a MAC control channel. These upstream channels can be used in different, physically separated coaxial cells where space division multiplexing (SDM) is applied or within a single cell where frequency division multiplexing (FDM) is applied. Mixed scenarios where space and frequency division multiplexing is applied in either upstream or downstream direction are also possible. Network scenarios showing when to apply SDM or FDM can be found in [guideline document]. An example of a frequency allocation for the FDM scenario is shown in Figure 26. This relationship consists of the following items: 1) Each of these related upstream channels share a common slot position. This reference is based on 1 millisecond time markers in case of OOB and 3 milliseconds time markers in case of IB that are derived via information transmitted via the downstream MAC control channel. 2) Each of these related upstream channels derive slot numbers from information provided in the downstream MAC control channel. 3) The Messaging needed to perform MAC functions for each of these related upstream channels is transmitted via the downstream MAC control channel. The Media Access Control Protocol supports multiple downstream Channels. In instances where multiple Channels are used, the INA shall specify a single OOB frequency called the Provisioning Channel, where NIU's perform Initialization and Provisioning Functions. Also, in networks where IB NIUs exist, provisioning should be included in at least one IB channel. An aperiodic message is sent on each downstream control channel which points to the downstream Provisioning Channel. In instances where only a single frequency is in use, the INA shall utilize that frequency for Initialization and Provisioning functions. The Media Access Control protocol supports multiple upstream channels. One of the available upstream channels shall be designated the Service Channel. It may be necessary to provide a Backup Service Channel to make the system more reliable e.g. in a noisy environment. The Service Channel and the Backup Service Channel, respectively, shall be used by NIU's entering the network via the Initialization and Provisioning procedure. The remaining upstream channels shall be used for upstream data transmission. In cases where only one upstream channel is utilized, the functions of the Service Channel shall reside in conjunction with regular upstream data transmission. The Provisioning channel is the frequency channel on which the Default configuration message is transmitted. There can be several Provisioning channels in the system. The Service channel is the frequency channel to which the Default configuration message field Service channel frequency points. The ranging following the Default configuration message is carried out on that Service channel. There can be several Service channels in the system. ETSI 50 ETSI EN 301 199 V1.2.1 (1999-06) Figure 26: Example of a frequency allocation for the FDM scenario Upstream frequency change All connections of a NIU are on the same frequency channel. The upstream frequency can be changed by Reprovision or Transmission control message. If any of these messages change the frequency, the frequency is changed immediately, all connections remain established. After each frequency change, the sign-on procedure is entered (compare subclause 5.5.5). Reservation grants are lost, fixed rate slots are kept: If the frequency change was made by the Transmission Control Message, the slot assignments remain the same. If the frequency change was made by the Reprovision Message, the slot assignments remain the same except if new slot assignments are provided in this message. Downstream frequency channel types Table 15: Possible combinations of downstream content types and physical channels (NIU Capabilities) MAC Data Case OOB IB QPSK QPSK IB 1 X X 2 X X 3 X X X 4 X X There are three types of content in the downstream direction MAC messages and MAC flags, data and video. There can be two types of physical channels: QSPK and QPSK IB downstream channels. The QPSK IB downstream channel may carry either MPEG or MAC messages directly on the physical layer frame structure. The possible combinations of the content and physical channels are shown in the following table. NOTE: The standard refers only to if frequencies as the RF frequency range will depend upon local regulations. therefore all the frequencies specified in the MAC messages are if frequencies as specified in subclause 5.1.2. Combination establishment The NIU tunes to either a QPSK or QPSK IB channel on which it locates the provisioning channel. The NIU tunes to it and gets its MAC information on that channel. If the Connect message gives a new downstream frequency, the MAC information is found on that frequency, if it is the same type of frequency channel. Change of downstream frequency The downstream frequency can be changed by using either Reprovision or Transmission control message. All NIU's connections which use the same physical frequency channel (DS QPSK or DS QPSK IB) are located on the same frequency. When the downstream frequency changes the connections on the earlier frequency remain established. ETSI 51 ETSI EN 301 199 V1.2.1 (1999-06) Change of combination The combination can be changed with Connect message only immediately after the sign-on procedure or with Reprovision message at any time. The signalling channel cannot be changed to a different type of downstream channel. 5.5.2.3 Relationship Between Physical Layer Slot Position Counter and MAC Slot Assignment M10 - M1 is a 10-bit superframe counter at the INA side, whereas the upstream slot position counter is an upstream slot counter at the NIUs side. The NIU slot position counter (M10 - M1 × 3 × mm = 6 for 3,088 Mbit/s and m = 12 for 6,176 Mbit/s) may be implemented as a 16-bit counter which is compared to the 13-bit slot numbers assigned by the INA in MAC messages (list assignment). When the counter value equals any assigned value, the NIU is allowed to send a packet upstream. 5.5.2.4 Access Modes (Contention / Ranging / Fixed rate / Reservation) Different access modes are provided to the NIUs within access regions specified by information contained in the slot boundary fields of the downstream superframes. The limits between access regions allow users to know when to send data on contention without risks of collision with data of Reservation or Fixed Rate regions. Also, the separation between reservation and fixed rate regions provides two ways of assigning slots to NIUs. The following rules define how to select access modes: • Data connections: When the INA assigns a connection ID to the NIU, it either specifies a slot list to be used (Fixed rate access) or the NIU shall use contention or reserved access by following this algorithm: When the NIU shall send more cells for a specific VPI/VCI than what was assigned by the INA, it can use contention access only if the number of cells to transmit is less than Maximum_contention_access_message_length (specified in the MAC Connect Message from the INA). The details of the contention access mechanism is explained below under a). The NIU can send one request for reservation access if the number of cells is less than Maximum_reservation_access_message_length (specified in the MAC Connect Message from the INA). If more cells shall be transmitted, the NIU shall send multiple requests for reservation access. If the NIU/STB is forced to use reservation access, and it has not yet been assigned a Reservation_ID, then it shall wait for an assignment before transmitting. • MAC messages: MAC messages can be sent on contention access or reservation access. Note that the VPI/VCI = 0/0x21 connection used for MAC messages is always set up, so the INA does not assign a particular connection ID which is normally used for reservation requests. Thus, in order to use reservation access, slots assigned for other connections may be used for MAC messages. a) Contention Access Contention Access indicates that data (MAC or bursty data traffic) is sent in the slots assigned to the contention access region in the upstream channel. It can be used either to send MAC messages or data. The VPI, VCI of the ATM cells are then used to determine the type and direction of the data in higher layers. Contention based access provides instant channel allocation for the NIU. The Contention based technique is used for multiple subscribers that will have equal access to the signalling channel. It is possible that simultaneous transmissions occur in a single slot, which is called a collision. The INA utilizes the reception indicators to inform the NIU's whether successful reception of ATM cells has been obtained. The NIU executes a separate contention process for each VPI/VCI connection that requires contention access. The contention process is initiated by transmitting the first cell in a contention slot. This contention slot is randomly chosen from the available contention slots in the first frame that contains at least one contention slot. The contention process has to wait until the reception indicator of the slot is received. If the indicator contains a positive acknowledgement, the cell has been successfully received, and the next cell, if present, can be transmitted by continuing the contention process. If the indicator contains a negative acknowledgement, a collision has been detected and the cell can be retransmitted according to the procedure defined below. If the reception indicator is not received (e.g. due to CRC error), the NIU proceeds as if a positive acknowledgement would have been received. ETSI 52 ETSI EN 301 199 V1.2.1 (1999-06) If a collision has occurred the NIU is not obliged to retransmit the cell that was originally transmitted. Instead it may choose to update the contents of the cell, transmit another cell belonging to the same VPI/VCI connection, or not to retransmit at all. In the latter case, the NIU is not allowed to restart a contention process for the same VPI/VCI connection at an earlier slot than the latest possible contention slot in which it could have retransmitted the cell in the first contention process. Note that the allowed choices make it possible for the NIU to update the queue status when the cell to be retransmitted is a grant request. A counter at the NIU/STB records the number, denoted by backoff_exponent, of collisions encountered by a cell. The backoff_exponent counter starts from a value determined by the Min_Backoff_Exponent variable. The backoff_exponent is used to generate a uniform random number between 1 and 2^backoff_exponent. This random number is used to schedule retransmission of the collided cell. In particular, the random number indicates the number of contention access slots the HtmlResAnchor NIU/STB shall wait before it transmits. The first transmission is carried out in a random cell within the contention based access region. If the counter reaches the maximum number, determined by the Max_Backoff_Exponent variable, the value of the counter remains at this value regardless of the number of subsequent collisions. After a successful transmission the backoff_exponent counter is reset to a value determined by the Min_Backoff_Exponent variable. Informational Statement: The random access algorithm is unstable; the INA is expected to have intelligence to detect an unstable state of the random access algorithm and to solve it. For minislot contention resolution, see subclause 5.6.3. b) Ranging Access Ranging access indicates that the data is sent in a slot preceded and followed by slots not used by other users. These slots allow users to adjust their clock depending on their distance to the INA such that their slots fall within the correct allocated time. They are either in the ranging slots region when the ranging control slot indicator b0 received during the previous superframe was 1 (or when b1-b6 = 55 to 63), or reserved if the INA indicates to the NIU that a specific slot is reserved for ranging(via the Ranging and Power Calibration Message). In the latter case, the NIU is forbidden from ranging in the ranging slots region before the assigned slot appears. Simultaneous transmissions in ranging slots are resolved through the procedure defined in Figure A.1. c) Fixed rate Access NOTE: Fixed rate is called contentionless in DAVIC. Fixedrate_Access indicates that data is sent in slots assigned to the fixed rate based access region in the upstream channel. These slots are uniquely assigned to a connection by the INA. d) Reservation Access Reservation Access implies that data is sent in the slots assigned to the reservation region in the upstream channel. These slots are uniquely assigned once to a connection by the INA. This assignment is made at the request of the NIU for a given connection. It is also allowed to use such assignment in the fixed rate region. 5.5.2.5 MAC Error Handling Procedures Error handling procedures are under definition (Time out windows, power outage, etc.) 5.5.2.6 MAC Messages in the Mini Slots MAC reservation request messages may also be transported in the minislot structure. The Start Field (SF) for the MAC messages is defined in subclause 5.6.2. Error correction and/or detection is performed using a 2 byte Reed Solomon code. Reed-Solomon encoding shall be performed on the 14 bytes following the Unique Word with T = 1. This process adds 2 parity bytes to the MAC Message in the Minislot to give a code word of (16,14). Reed-Solomon encoding is performed on the MAC Message in the Minislot before upstream data randomization. The shortened Reed-Solomon code shall be implemented by appending 239 bytes, all set to zero, before the information bytes at the input of a (255,253) encoder; after the coding procedure these bytes are discarded. ETSI 53 ETSI EN 301 199 V1.2.1 (1999-06) The Reed-Solomon code shall have the following generator polynomials: Code Generator Polynomial: g(x) = (x + µ0)( x + µ1), where µ = 02hex. Field Generator Polynomial: p(x) = x8 + x4 + x3 + x2 + 1. 4B 1B 13 B 2B 1B Unique S RS G Mini slot payload Word F B 2B 6B 5B MSG MAC Informa- Conf MAC address Type tion Elements MAC indicator Reserved Bit 7 6 .. 0 Figure 27: MAC messages in the minislots Unique Word = 0x00 FC FC F3 SF = Start Field (Bit 7: MAC indicator, always set to 1; Bit 6...0: reserved, shall be set to zero) RS = Reed Solomon Bytes GB = Guard Band Reservation Request Message The Reservation Request Message has the same structure as in the case it is transported in the upstream ATM slot. The MAC message structure for carrying the Reservation Request Message is shown in Figure 28. ETSI 54 ETSI EN 301 199 V1.2.1 (1999-06) 4B 1B 13 B 2B 1B Unique S RS G Mini slot payload Word F B 2B 6B 5B MSG MAC Informa- Conf MAC address tion Elements Type 3B 2B Res_ID (Res- S_Cnt erved) Figure 28: Reservation Request Message in the minislot MAC message structure ETSI 55 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.2.7 MAC Message Format The MAC message types are divided into the logical MAC states of Initialization, Sign On, Connection Management and Link Management. Messages in Italic represent upstream transmission from NIU to INA. MAC messages are sent using Broadcast or Singlecast Addressing. Singlecast address shall utilize the 48-bit MAC address. Table 16: MAC messages Message Addressing Type Value Type MAC Initialization, Provisioning and Sign-On Messages 0x00 Used for fragmented messages (continued message) (see note) Scast or Bcast 0x01 Provisioning Channel Message Broadcast 0x02 Default Configuration Message Broadcast 0x03 Sign-On Request Message Broadcast 0x04 Sign-On Response Message Singlecast 0x05 Ranging and Power Calibration Message Singlecast 0x06 Ranging and Power Calibration Response Message Singlecast 0x07 Initialization Complete Message Singlecast 0x08-0x0B [Reserved] 0x0C Security Sign-on (see note) Singlecast 0x0D Security Sign-on Response (see note) Singlecast 0x0E-0x1E [Reserved] 0x1F Wait (see note) Singlecast 0x20-0x3F MAC Connection Establishment and Termination Msgs 0x20 Connect Message Singlecast 0x21 Connect Response Message Singlecast 0x22 Reservation Request Message Singlecast 0x23 Unused Broadcast 0x24 Connect Confirm Message Singlecast 0x25 Release Message Singlecast 0x26 Release Response Message Singlecast 0x28 Reservation Grant Message Broadcast 0x29 Reservation ID Assignment Singlecast 0x2A Reservation Status Request Singlecast 0x2B Reservation ID Response Message Singlecast 0x2C Resource Request Message Singlecast 0x2D Resource Request Denied Message Singlecast 0x2E-0x2F [Reserved] 0x30 Main Key Exchange (see note) Singlecast 0x31 Main Key Exchange Response (see note) Singlecast 0x32 Quick Key Exchange (see note) Singlecast 0x33 Quick Key Exchange Response (see note) Singlecast 0x34 Explicit Key Exchange (see note) Singlecast 0x35 Explicit Key Exchange Response (see note) Singlecast 0x36-0x3F [Reserved] MAC Link Management Messages 0x27 Idle Message Singlecast 0x40 Transmission Control Message Scast or Bcast 0x41 Reprovision Message Singlecast 0x42 Link Management Response Message Singlecast 0x43 Status Request Message Singlecast 0x44 Status Response Message Singlecast 0x45-0x5F [Reserved] NOTE: Optional MAC messages for the security option. To support the delivery of MAC related information to and from the NIU, a dedicated Virtual Channel shall be utilized. The VPI,VCI for this channel shall be 0x000,0x0021. ETSI 56 ETSI EN 301 199 V1.2.1 (1999-06) The timer accuracy of the MAC messages shall be ± 3 ms in the NIU, and the INA shall take this into account. • Upstream MAC messages: AAL5 (as specified in ITU-T Recommendation I.363 [8]) adaptation shall be used to encapsulate each MAC PDU in an ATM cell. Upstream MAC information should be single 40 bytes cell messages. • Downstream OOB MAC messages: AAL5 (as specified in ITU-T Recommendation I.363 [8]) adaptation shall be used to encapsulate each MAC PDU in an ATM cell. Downstream OOB MAC information may be longer than 40 bytes. All Downstream MAC messages shall be restricted to less than or equal to 120 bytes. • Downstream IB MAC messages: Downstream IB MAC messages are limited to a size of 120 bytes and shall be carried in a single TS packet. Longer messages shall be split into separate messages. No AAL5 layer is defined for MPEG-2 TS cells. MAC messages shall therefore be sent as explained in subclause 5.3.2 using the three MAC Message Framing bits. • MAC Fragmentation Protocol (optional): Larger security MAC messages up to 512 bytes may optionally be supported using the MAC fragmentation protocol. This capability is indicated by the NIU in the MAC_Sign_On_Response. A multi-fragment MAC message is composed of consecutive individual MAC messages with Syntax_Indicator equal to Fragment_No_MAC_Address or Fragment_MAC_Address_Included. The Fragment_Count field of each individual MAC message indicates the number of fragments remaining of the full message, decreasing by one for each consecutive fragment. Thus the first fragment has Fragment_Count equal to the total number of fragments in the message, and the last fragment has Fragment_Count == 1. Furthermore, the type of MAC message is indicated by the Message_Type field of the first fragment, whereas all subsequent fragments have Message_Type == 0. The sender of a fragmented MAC message shall not interleave any other fragmented MAC messages for the same receiver into the string of fragments. This includes any fragmented broad-cast MAC messages, which shall therefore not be sent while there are any incomplete fragmented messages outstanding. MAC messages of unfragmented syntax type can be interleaved with fragments destined for the same NIU. They are deemed to have arrived before the fragmented message, and should be processed immediately. The receiver of a fragmented MAC message shall discard any message with missing fragments, as implied by the uniformly decreasing Fragment_Count field in consecutive fragments. Likewise, it shall discard any stray fragments with Message_Type == 0, for instance in the case where the first fragment was lost during transport. The length of each fragment is implied by its transport context: ATM/AAL-5 for upstream and OOB downstream, MPEG encapsulation for IB downstream, etc. The MAC_Information_Elements fields of each fragment are concatenated to form the MAC_Information_Elements field of the full MAC message. The message type is conveyed in the first fragment. In the upstream direction, all fragments shall be of syntax type Fragment_MAC_Address_Included, in order to allow the INA to use the MAC address to distinguish inter-mixed MAC messages and fragments coming from separate NIUs. For a broad-cast in the downstream direction, each fragment is of syntax type Fragment_No_MAC_Address. For a single-cast downstream message, the first fragment shall be of syntax type Fragment_MAC_Address_Included, and include the MAC address of the target NIU. Subsequent fragments can also include the same MAC address value, or can be Fragment_No_MAC_Address, omitting the MAC address, when the INA ensures that the fragment is associated with the immediately preceding fragment in the transport stream, that is, not separated by messages or fragments for other NIUs. ETSI 57 ETSI EN 301 199 V1.2.1 (1999-06) Since MAC related information is terminated at the NIU and INA, a privately defined message structure will be utilized. The format of this message structure is illustrated below. NOTE 1: All messages are sent most significant bit first. NOTE 2: For all MAC messages where the parameter length is smaller than the field, the parameter shall be right justified with leading bits set to 0. All reserved fields in the MAC messages shall be set to 0. NOTE 3: Message 0x23 is not used in the present release of the MAC protocol. It refers to DAVIC 1.0 protocol which is not supported by the present document. NOTE 4: When no MAC_Address is specified in the message, it means that the message is sent broadcast. (Syntax_indicator = 000). NOTE 5: Negative integers are sent in 2's complement. Table 17: MAC message structure MAC_message (){ Bits Bytes Bit Number / Description Message_Configuration 1 Protocol_Version 5 Syntax_Indicator 3 Message_Type 8 1 if (Syntax_Indicator == 001 || Syntax_Indicator == 011) { MAC_Address (48) (6) } if (Syntax_Indicator == 010 || Syntax_Indicator == 011)) { Fragment_Count (8) (1) } MAC_Information_Elements () N } MAC Information Elements MAC_Information_Elements is a multiple byte field that contains the body of one and only one MAC message. Protocol Version Protocol_Version is a 5-bit field used to identify the current MAC version. The value for this parameter is given in the following table. Table 18: Protocol_version coding Value Definition 0 DAVIC 1.0 Compliant device (not consistent with the present document) 1 DAVIC 1.1 Compliant device 2 DAVIC 1.2 Compliant device 3 - 19 Reserved 20 EN 301 199 compliant device 21 - 28 Reserved 29 ETS 300 800 [2] V2 compliant device 30 ETS 300 800 [2] V1 compliant device 31 Reserved ETSI 58 ETSI EN 301 199 V1.2.1 (1999-06) Syntax Indicator Syntax_Indicator is a 3-bit enumerated type that indicates the addressing type contained in the MAC message. Enum Syntax_Indicator {No_MAC_Address, MAC_Address_Included, Fragment_No_MAC_Address, Fragment_MAC_Address, reserved 4...7}; MAC Address MAC_Address is a 48-bit value representing the unique MAC address of the NIU. This MAC address may be hard coded in the NIU or be provided by external source. Fragment_Count Identification of fragment in a MAC message transmitted in multiple fragments. A MAC Message divided into N fragments, will be transmitted with Fragment_Count = N, N-1, ... 1. 5.5.3 MAC Initialization and Provisioning This subclause defines the procedure for Initialization and Provisioning that the MAC shall perform during power on or Reset. 1) Upon a NIU becoming active (i.e. powered up), it shall first find the current provisioning frequency. The NIU shall receive the Provisioning Channel Message. This message shall be sent aperiodically on all downstream channels carrying MAC information when there are multiple channels. In the case of only a single channel, the message shall indicate the current channel is to be utilized for Provisioning. Upon receiving this message, the NIU shall tune to the Provisioning Channel. In the case of IB downstream, the IB channel to be used during provisioning shall be given by using ETS 300 468 [6]. 2) After a valid lock indication on a Provisioning Channel, the NIU shall await the DEFAULT CONFIGURATION MESSAGE. When received, the NIU shall configure its parameters as defined in the default configuration message. The Default Configuration Parameters shall include default timer values, default power levels, default retry counts as well as other information related to the operation of the MAC protocol. Figure 29 shows the signalling sequence. INA NIU/STB Provisioning Channel Message Default Configuration Message Figure 29: Initialization and Provisioning signalling ETSI 59 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.3.1 Provisioning Channel Message (Broadcast OOB Downstream) The PROVISIONING CHANNEL MESSAGE is sent by the INA to direct the NIU to the proper frequency where provisioning is performed. The format of the message is shown in the following table. Table 19: Provisioning Channel Message Structure Provisioning_Channel_Message (){ Bits Bytes Bit Number / Description Provisioning_Channel_Control_Field 8 1 Reserved 7 7-1 1 0: {no = 0, yes = 1} Provisioning_Frequency_Included if (Provisioning_Frequency_Included) { Provisioning_Frequency (32) (4) DownStream_Type (8) (1) } } Provisioning Channel Control Field Provisioning_Channel_Control_Field is used to specify which parameters are included in the message: Provisioning_Frequency_Included is a Boolean when set, indicates that a downstream frequency is specified that the NIU should tune to begin the provisioning process. When cleared, indicates that the current downstream frequency is the provisioning frequency. Provisioning Frequency Provisioning_Frequency is a 32-bit unsigned integer representing the Out-of-band Frequency in which NIU provisioning occurs. The unit of measure is Hz. Downstream Type DownStream_Type is an 8-bit enumerated type indicating the modulation format for the down stream connection. {QPSK IB, reserved, QPSK_3,088, 3...255 reserved}} ETSI 60 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.3.2 Default Configuration Message (Broadcast Downstream) The DEFAULT CONFIGURATION MESSAGE is sent by the INA to the NIU. The message provides default parameter and configuration information to the NIU. The format of the message is shown in the following table. Table 20: Default configuration message structure Default_Configuration_Message (){ Bits Bytes Bit Number / Description Sign_On_Incr_Pwr_Retry_Count 8 1 Service_Channel_Frequency 32 4 Service_Channel_Control_Field 1 MAC_Flag_Set 5 7..3 Service_Channel 3 2..0 Backup_Service_Channel_Frequency 32 4 Backup_Service_Channel_Control_Field 1 Backup_MAC_Flag_Set 5 7..3 Backup_Service_Channel 3 2..0 Service_Channel_Frame_Length 16 2 Service_Channel_Last_Slot 16 2 Max_Power_Level 8 1 Min_Power_Level 8 1 Upstream_Control_Field 1 Reserved 5 7..3 Upstream_Transmission_Rate 3 2..0 Max_Backoff_Exponent 8 1 Min_Backoff_Exponent 8 1 Idle_Interval 16 2 Absolute_Time_Offset 16 2 frequency-ranging_step 8 1 Number_of_Timeouts 8 1 for (I=0; I Default Configuration Message, the default values apply. ETSI 63 ETSI EN 301 199 V1.2.1 (1999-06) Table 21: Head-end Timeout Values Code Transaction(s) Default Value 0x0 Ranging and power calibration -> Ranging and power calibration response 300 Connect -> Connect response (no frequency change) Release -> Release response Transmission control -> Link management response (no frequency change) Reservation ID assignment -> Reservation ID response Reprovision -> Link management response (no frequency change) Status request -> Status response message Init complete -> Connect response Init. complete -> Link management response 0x1 Connect -> Sign on response (only for frequency change) 3 000 Reprovision -> Sign on response (only for frequency change) Transmission control -> Sign on response (only for frequency change) The Unit for the timeouts is ms. These timeouts apply when the mentioned two messages are consecutive. Table 22: Terminal Timeout Values Code Transaction(s) Default Value 0x2 Default configuration interval(time between two Def. Conf. msg) 900 Sign on request interval 0x3 Sign on response -> Ranging and power calibration 90 Sign on response -> Initialization complete Ranging and power calibration response -> Ranging and power calibration Ranging and power calibration response -> Initialization complete Connect response -> Connect confirm Resource Request -> Release Resource Request -> Reservation_ID assignment 0x4 Initialization complete -> Connect 300 Resource Request -> Resource Request Denied Resource Request -> Connect Resource Request -> Reprovision The Unit for the timeouts is ms. These timeouts apply when the mentioned two messages are consecutive. INA_Capabilities INA_Capabilities is a 32-bit field that indicates the capabilities of the INA. It has the following subfields: Encapsulation is an 8-bit field that indicates the type(s) of encapsulation supported by the INA: {DIRECT_IP, Ethernet_MAC_Bridging, PPP, reserved 3...7} US_Bitrate is an 8-bit field that indicates the upstream bitrate(s) supported by the INA: {reserved, reserved, 3,088 Mbit/s, 6,176 Mbit/s, reserved 4...7} DS_OOB_Bitrate is a 4-bit field that indicates the downstream OOB bitrate(s) supported by the INA: {3,088 Mbit/s, reserved 2...3} Reserved: Reserved for future use Resource_Request_Capable is a 1-bit field that indicates if the INA is able to process Resource Request Messages. ETSI 64 ETSI EN 301 199 V1.2.1 (1999-06) Fragmented_MAC_Messages is a 1-bit field that indicates that the INA is able to support MAC messages having the compound MAC_Information_Elements field of a single up to 512 bytes in size. This flag is also for backwards compatibility with INAs not supporting MAC message fragmentation and re-assembly. By not setting this bit, the INA indicates that it does not support fragmented MAC messages at all, and will not understand or utilize the Fragment_No_MAC_Address and Fragment_MAC_Address_Included MAC message syntax types. Security_Suported is a 1-bit field that indicates that the INA is able to support the security extensions specified in this protocol. Minislots_for_Reservation is an 1-bit field that indicates that the INA is capable of utilizing minislots. Reserved_for_DAVIC: Reserved for compatibility with DAVIC. IB_Signalling is an 1-bit field that indicates that the INA is capable of utilizing IB signalling. OOB_Signalling is an 1-bit field that indicates that the INA is capable of utilizing OOB signalling. 5.5.4 Sign On and Calibration The NIU shall Sign On via the Sign-On Procedure. The signalling flow for Sign-On is described below. - The NIU shall tune to the downstream Provisioning channel and the upstream service channel with the information provided in the Initialization and Provisioning sequence. - The NIU shall await the Sign-On Request Message from the INA Entity. - Upon receiving the Sign-On Request Message, the NIU shall respond with the Sign-On Response Message. The Sign-On Response Message shall be transmitted on a Ranging Slot. The NIU/STB shall either use settings of the last successful Sign-on procedure if it is enabled by the INA or the Min_Power_Level contained in the Default Configuration Message. - The INA, upon receiving the Sign-On Response Message shall validate the NIU, either sending Initialization Complete Message or the Ranging and Power Calibration Message. - The NIU shall respond to the Ranging and Power Calibration Message with the Ranging and Power Calibration Response Message. The Ranging and Power Calibration Response Message shall be transmitted on a Ranging Slot (which can either be in the ranging region (b0 = 1) or reserved region (if a ranging slot number is given in the message). The calibration sequence is not always necessary. - The INA shall send the Initialization Complete Message when the NIU is calibrated. The NIU is assumed to be calibrated if the message arrives within a window of ± 0,75 symbols (upstream rate) and a power within a window of ± 1,5 dB from their optimal value. ETSI 65 ETSI EN 301 199 V1.2.1 (1999-06) INA NIU/STB Sign-On Message Sign-On Response Message Ranging and Power Calibration Message Ranging and Power Calibration Response Message Initialization Complete Figure 30: Ranging and Calibration Signalling A more detailed description of the ranging and calibration process, including state diagrams and time outs, is given in Annex A. 5.5.4.1 Sign-On Request Message (Broadcast Downstream) The Sign-On Request message is issued periodically by the INA to allow a NIU to indicate its presence in the network. The format of this subcommand is shown in the following table. Table 23: Sign-On Request Message Structure Sign-On_Request_Message (){ Bits Bytes Bit Number / Description Sign-On_Control_Field 1 Reserved 6 7..2 Need_Calibration 1 1: {0 = enable rapid sign-on, 1 = disable rapid sign-on} Address_Filter_Params_Included 1 0: {no, yes} Response_Collection_Time_Window 16 2 if (Sign-On_Control_Field &= Address_Filter_Params_Included { Address_Position_Mask (8) (1) Address_Comparison_Value (8) (1) } } Sign-On Control Field Sign-On_Control_Field specifies what parameters are included in the SIGN-ON REQUEST: Need_Calibration indicates to the NIU that it has to enter the sign-on process starting with the Min_Power_Level and Absolute_Time_Offset (and Frequency_Offset for LMDS) defined in the Default_Configuration_message. This bit is not to be taken into account the first time the NIU engages the sign-on process after power on, in this case it always starts with the parameters defined in the Default_Configuration_message. Address_Filter_Params_Included is a Boolean, when set, indicates that the NIU should respond to the SIGN-ON REQUEST only if its address matches the filter requirements specified in the message. ETSI 66 ETSI EN 301 199 V1.2.1 (1999-06) Response Collection Time Window Response_Collection_Time_Window is a 16-bit unsigned integer that specifies the maximum time for the SIGN-ON RESPONSE message transmission randomization. The unit of measure is the millisecond (ms). Address Position Mask Address_Position_Mask is an 8-bit unsigned integer that indicates the bit positions in the NIU MAC address that are used for address filtering comparison. The bit positions are comprised between bit number Mask and Mask+7. Mask = 0 corresponds to the 8 LSBs of the address, i.e., it represents the number of bits shifted to the left. The maximum value is 40. Address Comparison Value Address_Comparison_Value is an 8-bit unsigned integer that specifies the value that the NIU should use for MAC address comparison. Figure 31: Position of Mask in MAC address 5.5.4.2 Sign-On Response Message (Upstream Ranging) The Sign-On Response Message is sent by the NIU in response to the Sign-On Request Message issued by the INA Entity. The NIU shall wait for a random time less than Response_Collection_Time_Window to send this message. If the sign-on procedure did not start at the Min_Power_Level (see subclause 5.5.4), when the NIU has not received any response from the INA after Sign_On_Incr_Pwr_Retry_Count attempts, it shall retry with the Min_Power_Level. ETSI 67 ETSI EN 301 199 V1.2.1 (1999-06) Table 24: Sign-On response Message structure Sign-On_Response_Message (){ Bits Bytes Bit Number / Description NIU/STB_Status 4 Reserved 29 31..3 Network_Address_Registered 1 2: {no, yes} Connection_Established 1 1: {no, yes} Reserved 1 0 NIU/STB_Error_Code 2 Reserved 13 15..3 Connect_Confirm_Timeout 1 2: {no, yes} First_Connection_Timeout 1 1: {no, yes} Range_Response_Timeout 1 0: {no, yes} NIU/STB_Retry_Count 8 1 NIU/STB_Capabilities 4 Encapsulation 8 31..24 US_Bitrate 8 23..16 DS_OOB_Bitrate 4 15..12 Reserved 5 11..7: {no, yes} Resource_Request_Capable 1 6: {no, yes} Fragmented_MAC_Messages 1 5: {no, yes} Security_Supported 1 4: {no, yes} Minislots_for_Reservation 1 3: {no,yes} Reserved_for_DAVIC 1 2: shall be zero IB_Signalling 1 1: {no, yes} OOB_Signalling 1 0: {no, yes} } NIU/STB_Status NIU/STB_Status is a 32-bit field that indicates the current state of the NIU/STB. It has the following subfields: Network_Address_Registered indicates that the Network Interface Module has registered its NSAP Address with the Application Module. The NSAP Address is not currently used but remains reserved for this purpose. Connection_Established indicates that the Network Interface Module has been assigned Connection parameters. NIU/STB_Error_Code NIU/STB_Error_Code is an 16-bit field that indicates the error condition within the NIU/STB. It has the following subfields: Connect_Confirm_Timeout (set to 1 for transition SCE:E4 or DCE:E8) First_Connection_Timeout (set to 1 for transition DCE:E2) Range_Response_Timeout (set to 1 for transition RC:E13, Figure A.1) In case of a timeout in the current signalling, the corresponding subfield is set to one (Annex A). NIU/STB_Retry_Count NIU/STB_Retry_Count is a 8-bit unsigned integer that indicates the number of transmissions of the Sign-On Response. This field is always included in the response to the Sign-On Request. This field shall be initialized to zero whenever a Sign-On procedure is started, and this field shall be incremented by one each time the message is transmitted until the Sign-On procedure completes or the value reaches its maximum value (255). In the case that this field reaches its maximum value, it shall remain at the maximum value for the remainder of the current Sign-On procedure. ETSI 68 ETSI EN 301 199 V1.2.1 (1999-06) NIU/STB_Capabilities NIU/STB_Capabilities is a 32-bit field that indicates the capabilities of the NIU/STB. It has the following subfields: Encapsulation is an 8-bit field that indicates the type(s) of encapsulation supported by the NIU/STB: {DIRECT_IP, Ethernet_MAC_Bridging, PPP, reserved 3...7} US_Bitrate is an 8-bit field that indicates the upstream bitrate(s) supported by the NIU/STB: {reserved, reserved, 3,088 Mbit/s, 6,176 Mbit/s, reserved 4...7} DS_OOB_Bitrate is a 4-bit field that indicates the downstream OOB bitrate(s) supported by the NIU/STB: {3,088 Mbit/s, reserved 2...3} Reserved: Reserved for future use Resource_Request_Capable is a 1-bit field that indicates if the NIU is able to send Resource Request Messages. Fragmented_MAC_Messages is a 1-bit field that indicates that the NIU/STB is able to support MAC messages having the compound MAC_Information_Elements field of a single up to 512 bytes in size. This flag is also for backwards compatibility with NIU/STBs not supporting MAC message fragmentation and re-assembly. By not setting this bit, the NIU/STB indicates that it does not support fragmented MAC messages at all, and will not understand or utilize the Fragment_No_MAC_Address and Fragment_MAC_Address_Included MAC message syntax types. Security_Supported is a 1-bit field that indicates that the NIU/STB is able to support the security extensions specified in this protocol. Minislots_for_Reservation is a 1-bit field that indicates that the NIU/STB is capable of utilizing minislots. Reserved_for_DAVIC: Reserved for compatibility with DAVIC. IB_Signalling is an 1-bit field that indicates that the NIU/STB is capable of utilizing IB signalling. OOB_Signalling is an 1-bit field that indicates that the NIU/STB is capable of utilizing OOB signalling. 5.5.4.3 Ranging and Power Calibration Message (Singlecast Downstream) The RANGING AND POWER CALIBRATION MESSAGE is sent by the INA to the NIU to adjust the power level or time offset the NIU is using for upstream transmission. The format of this message is shown in the following table. Minislots are not used for ranging. ETSI 69 ETSI EN 301 199 V1.2.1 (1999-06) Table 25: Ranging and Power Calibration Message structure Ranging_and_Power_Calibration_Message (){ Bits Bytes Bit Number / Description Range_Power_Control_Field 1 Reserved 5 7-3: frequency_adjustment_included 1 3: {no, yes} Ranging_Slot_Included 1 2: {no, yes} Time_Adjustment_Included 1 1: {no, yes} Power_Adjustment_Included 1 0: {no, yes} if (Range_Power_Control_Field &= Time_Adjustment_Included ) { Time_Offset_Value (16) (2) } if (Range_Power_Control_Field &= Power_Adjustment_Included ) { Power_Control_Setting (8) (1) } if (Range_Power_Control_Field &= Ranging_Slot_Included) { Ranging_Slot_Number (16) (2) } if (range_frequency_control-field = = frequency_adjustement_included) { Frequency_Offset_Value (32) (4) } } Range and Power Control Field Range_Power_Control_Field specifies which Range and Power Control Parameters are included in the message. Frequency Adjustment Included frequency_adjustment_included is a Boolean when set, indicates that a relative upstream frequency offset value is included that the NIU should use to adjust its upstream IF frequency. Time Adjustment Included time_adjustment_included is a Boolean when set, indicates that a relative Time Offset Value is included that the NIU should use to adjust its upstream slot transmit position. Power Adjust Included power_adjust_included is a Boolean when set, indicates that a relative Power Control Setting is included in the message Ranging Slot Included Ranging_Slot_Included is a Boolean when set, indicates the calibration slot available. When this bit equals 1, the NIU shall send its response on the slot number given by Ranging Slot Number. When this bit equals 0, the NIU shall respond on a ranging slot as mentioned in Figure A.1. Time Offset Value Time_Offset_Value is a 16-bit short integer representing a relative offset of the upstream transmission timing. A negative value indicates an adjustment forward in time (later). A positive value indicates an adjustment back in time (earlier). The unit of measure is 100 ns (The NIU will adjust approximately its time offset to the closest value indicated by the Time_Offset_Value parameter, which implies that no extra clock is needed to adjust to the correct offset). ETSI 70 ETSI EN 301 199 V1.2.1 (1999-06) Power Control Setting Power_Control_Setting is an 8-bit signed integer to be used to set the new power level of the NIU. (A positive value represents an increase of the output power level) New output_power_level = current output_power_level + power_control_setting × 0,5 dB Ranging Slot Number Ranging_Slot_Number is a 16-bit unsigned integer that represents the reserved access Slot Number assigned for Ranging the NIU. It shall be assigned by the INA in the reservation area. The INA shall assure that an unassigned slot precedes and follows the ranging slot. Only 13 lowest significant bits shall be considered. 3 MSB are reserved for future used. Frequency Offset value Frequency_Offset_Value is a 32-bit signed integer representing the upstream carrier offset frequency compared to the centre IF frequency. The unit of measure is in Hz. 5.5.4.4 Ranging and Power Calibration Response Message (Upstream Ranging or reserved) The RANGING AND POWER CALIBRATION RESPONSE Message is sent by the NIU to the INA in response to the RANGING AND POWER CALIBRATION MESSAGE. The format of the message is shown in the following table. Table 26: Ranging and Power Calibration Response Message Structure Ranging_Power_Response_Message (){ Bits Bytes Bit Number / Description Power_Control_Setting 8 1 } Power Control Setting Power_Control_Setting is an 8-bit unsigned integer representing the actual power used by the NIU for upstream transmission. The unit of measure is 0,5 dBµV. 5.5.4.5 Initialization Complete Message (Singlecast Downstream) The INITIALIZATION COMPLETE Message is sent by the INA to the NIU/STB to indicate the end of the HtmlResAnchor MAC Sign-On and Provisioning procedure. The STB/NIU shall re-enter the initialization process after receiving a non-zero Completion_Status_Field value. The Transmission Control Message can be used to stop the NIU from sending upstream messages. Table 26a Initialization_Complete_Message (){ Bits Bytes Bit Number / Description Completion_Status_Field 1 Reserved 4 7..4 Invalid_STB/HtmlResAnchor NIU 1 3: {no, yes} Timing_Ranging_Error 1 2: {no, yes} Power_Ranging_Error 1 1: {no, yes} Other_Error 1 0: {no, yes} } ETSI 71 ETSI EN 301 199 V1.2.1 (1999-06) Completion_Status_Field Completion_Status_Field is an 8-bit field that indicates errors in the initialization phase. It has the following subfields: Invalid_STB/HtmlResAnchor NIU is a Boolean that (when set to 1) indicates that the STB/NIU is invalid. Timing_Ranging_Error is a Boolean that (when set to 1) indicates that the ranging has not succeeded. Power_Ranging_Error is a Boolean that (when set to 1)indicates that the power ranging has not succeeded. Other_Error is a Boolean that (when set to 1) indicates an error with unspecified type. 5.5.4.6 Frequency ranging It can happen in LMDS systems that the NIU upstream frequency doesn't fit into the service channel demodulator frequency window, as the upstream frequency uncertainty is specified to be ± 200 kHz at the reference point B1, while the detection window of a burst demodulator is usually lower than 100 kHz. In that case, the NIU will perform the normal ranging procedure described in Figure 30. When the NIU doesn't receive a Ranging and Power calibration message, it will change its upstream frequency with the procedure illustrated in the figure below: first Df, than -DF, than + 2DF, etc. DF being the frequency_ranging_step defined in the default_configuration _message. In the example below, the NIU first tries at a frequency outside the demodulator window; at the third attempt, it falls within the window, and receives a Ranging and Power calibration Message with a frequency_offset parameter to shift the NIU frequency at the middle of the demodulator window. Demodulator center frequency Demodulator detection window - 2 DF + DF 3rd 1st 2nd UPSTREAM attempt attempt attempt FREQUENCY Figure 31a 5.5.5 Connection Establishment Two cases shall be considered: 1) establishment of the first (initial) connection; 2) establishment of additional connections. ETSI 72 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.5.1 Establishment of the First (Initial) Connection After Initialization, Provisioning and Sign On Procedures are complete, the INA shall assign an upstream and downstream connection to the NIU. This connection can be assigned on any of the upstream channels. The INA shall assign the connection by sending the Connect Message to the NIU. This message shall contain the upstream connection parameters and downstream frequency on which the connection is to reside. The NIU, upon receiving the Connect Message shall tune to the required upstream and downstream frequencies and send the Connect Response Message confirming receipt of the message. However, if the US and/or the DS frequency contained in the Connect Message is different than the current US and/or DS frequency, the NIU/STB shall tune to the new frequency and enter the Sign-On procedure as defined in subclause 5.5.4, the Connection_Established flag being set and the NIU/STB retry count reset. The NIU/STB shall send the Connect Response Message after the Initialization Complete Message. Upon receipt of the Connect Response Message, the INA shall confirm the new connection by sending the Connect Confirm Message. INA NIU/STB Connect Message Connect Response Connect Confirm Figure 32: Connection Signalling for the Initial Connection A more detailed description of the connection establishment process, including state diagrams and time outs, is given in Annex A. ETSI 73 ETSI EN 301 199 V1.2.1 (1999-06) Connect Message (Singlecast Downstream) Table 27: Connect Message Structure Connect_Message (){ Bits Bytes Bit Number / Description Connection_ID 32 4 Session_Number 32 4 Connection_Control_Field_Aux 1 Reserved 6 7..2: shall be 0 Encapsulation_Included 1 1: {no, yes} DS_Multiprotocol_CBD_Included 1 0: {no, yes} Resource_Number 8 1 Connection_Control_Field 1 DS_ATM_CBD_Included 1 7: {no, yes} DS_MPEG_CBD_Included 1 6: {no, yes} US_ATM_CBD_Included 1 5: {no, yes} Upstream_Channel_Number 3 4..2 Slot_List_Included 1 1: {no, yes} Cyclic_Assignment 1 0: {no, yes} Frame_Length 16 2 Maximum_Contention_Access_Message_Length 8 1 Maximum_Reservation_Access_Message_Length 8 1 if(Connection_Control_Field &= DS_ATM_CBD_Included) { Downstream_ATM_CBD() (64) (8) } if (Connection_Control_Field &= DS_MPEG_CBD_Included) { Downstream_MPEG_CBD() (48) (6) } if (Connection_Control_Field &= US_ATM_CBD_Included) { Upstream_ATM_CBD() (64) (8) } if (Connection_Control_Field &= Slot_List_Included) { Number_Slots_Defined (8) (1) for (i=0;iConnect Response Message shall be sent). Frame Length Frame_length - This 16-bit unsigned number represents the number of successive slots in the fixed rate access region associated with each fixed rate slot assignment. In the slot_list method of allocating slots it represents the number of successive slots associated with each element in the list. In the cyclic method of allocating slots it represents the number of successive slots associated with the Fixedrate_Start_slot and those which are multiples of Fixedrate_Distance from the Fixedrate_Start_slot within the Fixed rate access region. Maximum Contention Access Message Length Maximum_contention_access_message_length is an 8-bit number representing the maximum length of a message in ATM sized cells that may be transmitted using contention access. Any message greater than this should use reservation access. ETSI 75 ETSI EN 301 199 V1.2.1 (1999-06) Maximum Reservation Access Message Length Maximum_reservation_access_message_length is an 8-bit number representing the maximum length of a message in ATM sized cells that may be transmitted using a single reservation access. Any message greater than this shall be transmitted by making multiple reservation requests. Downstream ATM Connection Block Descriptor Table 28: Downstream_ATM_CBD substructure Downstream_ATM_CBD (){ Bits Bytes Bit Number / Description Downstream_Frequency 32 4 Downstream_VPI 8 1 Downstream_VCI 16 2 Downstream_Type 8 1 } Downstream_Frequency is a 32-bit unsigned integer representing the Frequency where the connection resides. The unit of measure is in Hz. Downstream_VPI is an 8-bit unsigned integer representing the ATM Virtual Path Identifier that is used for downstream transmission over the Dynamic Connection. Downstream_VCI is an 16-bit unsigned integer representing the ATM Virtual Channel Identifier that is used for downstream transmission over the Dynamic Connection. DownStream_Type is an 8-bit enumerated type indicating the modulation format for the down stream connection. {QPSK IB, reserved, QPSK_3,088, 3...255 reserved} Downstream MPEG Connection Block Descriptor Table 29: Downstream_MPEG_CBD substructure Downstream_MPEG_CBD (){ Bits Bytes Bit Number / Description Downstream_Frequency 32 4 Program_Number 16 2 } Downstream_Frequency is a 32-bit unsigned integer representing the Frequency where the connection resides. The unit of measure is in Hz. Program_Number is a 16-bit unsigned integer uniquely referencing the downstream virtual connection assignment (PID of the MPEG-2 program, not equal to the program number defined by MPEG-2!). Only the 13 least significant bits are valid, the three most significant bits are reserved for future use. Upstream ATM Connection Block Descriptor Table 30: Upstream_ATM_CBD substructure Upstream_ATM_CBD (){ Bits Bytes Bit Number / Description Upstream_Frequency 32 4 Upstream_VPI 8 1 Upstream_VCI 16 2 1 MAC_Flag_Set 5 7..3 Upstream_Rate 3 2..0 } ETSI 76 ETSI EN 301 199 V1.2.1 (1999-06) Upstream_Frequency is a 32-bit unsigned integer representing the channel on assigned to the connection. The unit of measure is in Hz. Upstream_VPI is an 8-bit unsigned integer representing the ATM Virtual Path Identifier that is used for upstream transmission over the Dynamic Connection. Upstream_VCI is an 16-bit unsigned integer representing the ATM Virtual Channel Identifier that is used for upstream transmission over the Dynamic Connection. MAC_Flag_Set is a 5-bit field representing the first HtmlResAnchor MAC Flag set assigned to the logical channel. A downstream channel contains information for each of its associated upstream channel. This information is contained within structures known as MAC Flag Sets represented by either 24 bits (denoted b0...b23) or by 3 bytes (denoted Rxa, Rxb, Rxc). This information is uniquely assigned to a given upstream channel. See subclauses 5.3.1.3 and 5.3.2.1 for the use of this parameter. Upstream_Rate is an 3-bit enumerated type indicating the upstream transmission bit rate for the upstream connection. {reserved, reserved, Upstream_3,088 M, Upsteam_6,176 M, 4...7 reserved} Number of Slots Defined Number_Slots_Defined is an 8-bit unsigned integer that represents the number of slot assignments contained in the message. The unit of measure is slots. Slot Number Slot_Number is a 16-bit unsigned integer that represents the Fixed rate based Slot Number assigned to the NIU. Only 13 lowest significant bits shall be considered. 3 MSB are reserved for future used. Fixed Rate Start Fixedrate_Start - This 16-bit unsigned number represents the starting slot within the fixed rate access region that is assigned to the NIU. The NIU may use the next Frame_length slots of the fixed rate access regions. Only 13 lowest significant bits shall be considered. 3 MSB are reserved for future used. Fixed Rate Distance Fixedrate_Distance - This 16-bit unsigned number represents the distance in slots between additional slots assigned to the NIU. The NIU is assigned all slots that are a multiple of Fixedrate_Distance from the Fixedrate_Start_slot which don't exceed Fixedrate_End_slot The NIU may use the next Frame_length slots of the fixed rate access regions from each of these additional slots. Fixed Rate End Fixedrate_End - This 16-bit unsigned number indicates the last slot that may be used for fixed rate access. The slots assigned to the NIU, as determined by using the Fixedrate_Start_slot, the Fixedrate_Distance and the Frame_length, cannot exceed this number. Only 13 lowest significant bits shall be considered. 3 MSB are reserved for future use. Downstream Multiprotocol Connection Block Descriptor Table 31: Downstream_Multiprotocol_CBD substructure Downstream_Multiprotocol_CBD (){ Bits Bytes Bit Number / Description MAC_Address 48 6 } MAC_Address is a 48-bit MAC address, identifying an additional MAC address (used for example for multicast) to filter on in the DVB Multiprotocol Encapsulation header, according to EN 301 192 [3]. By default the NIU filters on its own MAC address and the Broadcast MAC address FF:FF:FF:FF:FF:FF. Encapsulation is an 8-bit field that indicates the type of encapsulation provided: {Direct_IP, Ethernet_MAC_Bridging, PPP, reserved 3...7}. ETSI 77 ETSI EN 301 199 V1.2.1 (1999-06) Connect Response (Upstream Contention or Reserved) The CONNECT RESPONSE MESSAGE is sent to the INA from the NIU in response to the CONNECT MESSAGE. The message shall be transmitted on the upstream frequency specified in the CONNECT MESSAGE. If the Upstream frequency is different than the current upstream frequency, then the procedure described in subclause 5.5.4 shall be used before the Connect Response Message is sent. If the Connect Confirm message does not arrive within the specified time interval, the NIU shall re-send the Connect Response message. Table 32: Connect response message structure Connect_Response (){ Bits Bytes Bit Number / Description Connection_ID 32 4 } Connection ID Connection_ID is a 32-bit unsigned integer representing a global connection Identifier for the NIU Dynamic Connection. Connect Confirm (Singlecast Downstream) The Connect Confirm message is sent from the INA to the NIU. Table 33: Connect Confirm message structure Connect_Confirm (){ Bits Bytes Bit Number / Description Connection_ID 32 4 } Connection ID Connection_ID is a 32-bit unsigned integer representing a global connection Identifier for the NIU Dynamic Connection. 5.5.5.2 Establishment of Additional Connections The INA can assign additional connections by using the Connect Message described previously. The NIU can request such connections using the Resource Request Message. Besides from that, the message sequence is the same as for the initial connection, with the following restrictions: • The US frequency shall be the same for all connections, and the OOB and IB frequencies shall be the same for all OOB and IB connections respectively. • If a Connect Message is received with new values of US and/or DS frequency, the NIU/STB will ignore the message. • If needed, the INA will use one of the resource management procedure to modify the US or DS frequency (see subclauses TDMA Allocation Management and Link Management) before sending the additional Connect Message. ETSI 78 ETSI EN 301 199 V1.2.1 (1999-06) INA NIU/STB Resource Request ConnectMessage Connect Response Connect Confirm Figure 33: Connection signalling for additional connections A more detailed description of the connection establishment process, including state diagrams and time outs, is given in Annex A. Resource Request Message (Upstream) The NIU may request a new connection, may request to change the parameters of an existing connection and may request to release an existing connection by sending a Resource Request Message to the INA. The INA can answer to that request by sending a Connect Message, a Reservation_ID Assignment Message / Reprovision Message or a Release Message, respectively, to the NIU or by sending a Resource Request Denied Message to the NIU. Table 34: Resource Request Message Structure Resource_Request_Message (){ Bits Bytes Bit Number / Description Resource_Request_ID 8 1 Connection_ID 32 4 Field 1 Reserved 5 7..3: shall be zero Release_Requested 1 2: {no, yes} Reservation_ID_Requested 1 1: {no, yes} Cyclic_Assignment_Needed 1 0: {no, yes} Requested_Bandwidth 24 3 The unit is slots/1 200 ms Maximum_Distance_Between_Slots 16 2 The unit is slots Encapsulation 8 1 } Resource_Request_ID is an 8-bit unsigned integer which identifies the resource request. The value of the Resource_Request_ID is incremented by one for every new resource request of the NIU. Connection_ID is a 32-bit field which identifies the connection for which changes are requested. If the value of Connection_ID is zero, a new connection is requested. Reserved: Reserved for future use. Shall be zero. Release_Requested: If set to one, the release of the connection is requested. In this case, all following parameters of the message shall be ignored by the INA. Reservation_ID_Requested: If set to one, a Reservation_ID is requested for the connection. Cyclic_Assignment_Needed: If set to one, cyclic assignment is requested for fixed rate access for the connection. If Requested_Bandwidth is zero, this field is ignored by the INA. ETSI 79 ETSI EN 301 199 V1.2.1 (1999-06) Requested_Bandwidth: Gives the requested bandwidth for fixed rate access for the connection in slots/300 ms. Maximum_Distance_Between_Slots: Gives the requested maximum distance between assigned fixed rate slots. If Requested_Bandwidth is zero, this field is ignored by the INA. Encapsulation is an 8-bit field that indicates the type of encapsulation requested: {Direct_IP, Ethernet_MAC_Bridging, PPP, reserved 3...7}. Resource Request Denied Message (Singlecast Downstream) The INA may respond to a resource request of the NIU with a Resource Request Denied Message: Table 35: Resource Request Denied Message Structure Resource_Request_Denied_Message (){ Bits Bytes Bit Number / Description Resource_Request_ID 8 1 } Resource_Request_ID is an 8-bit unsigned integer which identifies the resource request which is denied. 5.5.6 Connection Release This subclause defines the MAC signalling requirements for connection release. Figure 34 below displays the signalling flow for releasing a connection. The NIU can request the release of a connection using the Resource Request Message. 1) The NIU may request the release of a connection using the Resource Request Message, or the INA itself can initiate the release process. 2) Upon receiving the Release Message from the INA, the NIU shall tear down the upstream connection established for the specified Connection_ID. 3) Upon teardown of the upstream connection, the NIU shall send the Release Response Message on the upstream channel previously assigned for that connection. If the Connection_ID is unknown by the NIU, it shall send zero in the response message. If the Number_of_Connections in the Connection Release Message is zero, then the NIU shall release all open connections. INA NIU/STB Resource Request Release Message Release Response Figure 34: Connection release signalling A more detailed description of the connection release process, including state diagrams and time outs, is given in Annex A. Release Message (Singlecast Downstream) The Release Message is sent from the INA to the NIU to terminate a previously established connection. ETSI 80 ETSI EN 301 199 V1.2.1 (1999-06) Table 36: Release Message Structure Release_Message (){ Bits Bytes Bit Number / Description Number_of_Connections 8 1 for(i=0;i Release Response (Upstream contention or reserved) The RELEASE RESPONSE MESSAGE is sent by the NIU to the INA to acknowledge the release of a connection. The format of the message is shown in the following table. Table 37: Release Response Message structure Release_Response_Message (){ Bits Bytes Bit Number / Description Connection_ID 32 4 } Connection ID Connection_ID is a 32-bit unsigned integer representing the global connection Identifier used by the NIU for this connection. 5.5.7 Fixed Rate Access Fixed rate access is provided by the INA using the Connect Message. The INA is also allowed to assign slots in fixed rate access to a connection in response to a Reservation Request Message. 5.5.8 Contention Based Access The NIU shall use contention based slots specified by the slot boundary definition fields (Rx) to transmit contention based messages (see subclause 5.3). The format of contention based MAC messages is described by the MAC message format (see subclause 5.5.2.3). ETSI 81 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.9 Reservation Access This subclause defines the MAC signalling requirements for reservation access. Figure 35 below displays the signalling flow for reserving an access. INA NIU/STB Resource Request Reservation_ID Assignment Message Reservation_ID Response Message Reservation Request Message Reservation Grant Message Figure 35: Reservation access signalling 1) The NIU can request a Reservation_ID using the Resource Request Message. 2) The NIU shall wait for a Reservation ID Assignment Message from the INA before it can request reservation access. 3) At any time when needed after receiving the reservation ID, the NIU can request a certain number of slots to the INA using the Reservation Request Message. 4) The INA shall respond to that message using the Reservation Grant Message. 5) If the NIU has not received the Reservation Grant Message before the Grant_Protocol_Timeout, it shall send a Reservation Status Request to the INA. This leads back to 3. A more detailed description of the reservation process, including state diagrams and time outs, is given in Annex A. Reservation ID Assignment Message (Singlecast Downstream) The Reservation ID Assignment Message is used to assign the NIU a Reservation_ID. The NIU identifies its entry in the Reservation_grant_message by comparing the Reservation_ID assigned to it by the Reservation_ID_assignment_message and the entries in the Reservation_Grant_message. The format of the message is given in the following table. Table 38: Reservation ID assignment message structure Reservation_ID_Assignment_Message (){ Bits Bytes Bit Number / Description Connection_ID 32 4 Reservation_ID 16 2 Grant_protocol_timeout 16 2 } ETSI 82 ETSI EN 301 199 V1.2.1 (1999-06) Connection ID Connection_ID is a 32-bit unsigned integer representing a global connection identifier for the NIU Dynamic Connection. Reservation_ID Reservation_ID is a 16-bit unsigned number representing an identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate Reservation_Grant_Messages. Grant_protocol_timeout Grant_protocol_timeout is a 16-bit unsigned number representing the time in milliseconds that the NIU should wait before verifying the status of pending grants. This parameter specifies the time that the NIU should wait after receiving the last Reservation_grant_message, with an entry addressed to the NIU, before initiating a reservation status request. If the NIU has pending grants and the timeout occurs, it should send the Reservation_status_request message to the INA. The INA will respond with the Reservation_grant_message (probably without granting any slots) to inform the NIU of any remaining slots left to be granted. This allows the NIU to correct any problems should they exist such as issuing an additional request for slots or waiting patiently for additional grants. Reservation ID Response Message (Upstream contention or reserved) The Reservation ID Response Message is used to acknowledge the receipt of the Reservation_ID_Assignment message. The format of the message is given below. Table 38a Reservation_ID_Response_Message (){ Bits Bytes Bit Number / Description Connection_ID 32 4 Reservation_ID 16 2 } Connection ID Connection_ID is a 32-bit unsigned integer representing a global connection identifier for the NIU/STB Dynamic Connection. Reservation_ID Reservation_ID is a 16-bit unsigned number representing an identifier for the connection. This is used as a short identifier by the NIU/STB to identify the appropriate Reservation_Grant_Messages. Reservation Request Message (Upstream contention or reserved) Table 39: Reservation Request Message structure Reservation_Request_message (){ Bits Bytes Bit Number / Description Reservation_ID 16 2 Reservation_request_slot_count 8 1 } This message is sent from the NIU to the INA. Reservation_ID Reservation_ID is a 16-bit unsigned number representing an identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate Reservation_Grant_Messages. ETSI 83 ETSI EN 301 199 V1.2.1 (1999-06) Reservation Request Slot Count Reservation_request_slot_count is an 8-bit unsigned number representing the number of slots requested by the NIU. This is the number of sequential slots that will be allocated in the reservation region of the upstream channel. The INA will respond with the Reservation_Grant message granting the request. Reservation Grant Message (Broadcast Downstream) The RESERVATION GRANT MESSAGE is used to indicate to the NIU which slots have been allocated in response to the Reservation Request message. The NIU identifies its entry in the Reservation_grant_message by comparing the Reservation_ID assigned to it by the Reservation_ID_assignment_message and the entries in the Reservation_Grant_message. The format of the message is given in the following table. Table 40: Reservation Grant Message structure Reservation_grant_message (){ Bits Bytes Bit Number / Description Reference_slot 16 2 Number_grants 8 1 for (I=0; I Reservation Status Request (Upstream contention or reserved) The RESERVATION STATUS REQUEST Message is used to determine the status of the outstanding grants to be assigned by the INA. This message is only sent after the Grant protocol time-out is exceeded. The INA will respond with the Reservation_grant_message (possibly without granting any slots) to inform the NIU of any remaining slots left to be granted. This allows the NIU to correct any problems should they exist such as issuing an additional request for slots or waiting patiently for additional grants. ETSI 86 ETSI EN 301 199 V1.2.1 (1999-06) The format of the message is given in the following table. Table 41: Reservation status request message structure Reservation_Status_Request_Message (){ Bits Bytes Bit Number / Description Reservation_ID 16 2 Remaining_request_slot_count 8 1 } Reservation_ID Reservation_ID is a 16-bit unsigned number representing an identifier for the connection. This is used as a short identifier by the NIU to identify the appropriate Reservation_Grant_Messages. Remaining_request_slot_count Remaining_request_slot_count is an 8-bit unsigned number representing the number of slots that the NIU is expecting to be granted. 5.5.10 MAC Link Management The MAC Link Management tasks provide continuous monitoring and optimization of upstream resources. These functions include: - Power and Timing Management; - Fixed rate Allocation Management; - Channel Error Management. 5.5.10.1 Power and Timing Management Power and Timing Management shall provide continuous monitoring of upstream transmission from the NIU. The Ranging and Power Calibration Message is used to maintain a NIU within predefined thresholds of power and time. The Upstream Burst Demodulator shall continuously monitor the upstream burst transmissions from an NIU. Upon detection of an NIU outside the predefined range, the INA shall send the Ranging and Power Calibration Message to the NIU. The NIU/STB upstream power accuracy shall be better than or equal to ± 1,5 dB. The NIU/STB power resolution shall be 0,5 dB nominally. A detailed description of the re-calibration process, including state diagrams and time outs, is given in Annex A. 5.5.10.2 TDMA Allocation Management To ensure optimum assignment of TDMA resources, the INA shall ensure the upstream allocation of TDMA resources for various connections remain intact when allocating resources to a new connection. However, in the event that reconfiguration is required to minimize fragmentation of resources, then the INA shall dynamically reconfigure the upstream TDMA assignments to a NIU or group of NIUs. The Reprovision Message is utilized to change previously established connection parameters. The NIU can request the change of some parameters of existing connections by use of the Resource Request Message, in which case the Reprovision Message can be used by the INA to confirm the requested changes. A detailed description of the reprovisioning process, including state diagrams and time outs, is given in Annex A. Reprovision Message (Singlecast Downstream) The REPROVISION MESSAGE is sent by the INA to the NIU to reassign upstream resources (maintaining the originally requested QoS parameters at the establishment of the connection.) This message is intended for Fixed rate based channel maintenance by the INA to redistribute or reassign resources allocated to a NIU. ETSI 87 ETSI EN 301 199 V1.2.1 (1999-06) Table 42: Reprovision Message structure Reprovision_Message (){ Bits Bytes Bit Number / Description Reprovision_Control_Field 1 Reserved 1 7 Delete_Reservation_IDs 1 6: {no, yes} New_Downstream_IB_Frequency 1 5: {no, yes} New_Downstream_OOB_Frequency 1 4: {no, yes} New_Upstream_Frequency_Included 1 3: {no, yes} New_Frame_Length_Included 1 2: {no, yes} New_Cyclical_Assignment_Included 1 1: {no, yes} New_Slot_List_Included 1 0: {no, yes} if (Reprovision_Control_Field &= New_Downstream_IB_Frequency) { New_Downstream_IB_Frequency (32) (4) } if (Reprovision_Control_Field &= New_Downstream_OOB_Frequency) { New_Downstream_OOB_Frequency (32) (4) DownStream_Type (8) (1) } if (Reprovision_Control_Field &= New_Frequency_Included) { New_Upstream_Frequency (32) (4) New Upstream Parameters (2) New_Upstream_Channel Number (3) 15..13 Reserved (2) 12..11 Upstream_Rate (3) 10..8: enum MAC_Flag_Set (5) 7..3 Reserved (3) 2..0 } if (Reprovision_Control_Field &= New_Frame_Length_Included){ New_Frame_Length (16) (2) 9-0: Unsigned } if (Reprovision_Control_Field &= New_Slot_List_Included || New_Cyclical_Assignment_Included || Delete_Reservation_IDs){ Number_of_Connections (8) (1) for(i=0;i transmission by an NIU), the NIU shall enter an Idle Mode. Idle mode is characterized by periodic transmission by the NIU of a Idle Message. The Idle Mode transmission shall occur at a periodic rate sufficient for the INA to establish Packet Error Rate statistics. The Idle Message shall be sent only when the NIU/STB has at least one connection, after the Connect Confirm Message is received. A detailed description of idle message transmission, including state diagrams and time outs, is given in Annex A. Idle Message (Upstream contention or reserved) The Idle Message is sent by the NIU within the STB to the INA at predefined intervals (between 1 and 10 minutes) when the NIU is in idle mode. Table 43: Idle Message structure Idle_Message (){ Bits Bytes Bit Number / Description Idle_Sequence_Count 8 1 Power_Control_Setting 8 1 } Idle Sequence Count Idle_Sequence_Count is a 8-bit unsigned integer representing the count (modulo 256) of IDLE MESSAGES transmitted while the NIU is Idle. It counts the number of transmitted Idle Messages since the last sign-on, thus it starts counting at 0. Power Control Setting Power_Control_Setting is an 8-bit unsigned integer representing the actual power used by the NIU/STB for upstream transmission. The unit of measure is 0,5 dBµV. ETSI 90 ETSI EN 301 199 V1.2.1 (1999-06) 5.5.10.4 Link Management Messages Transmission Control Message (Singlecast or Broadcast Downstream) The TRANSMISSION CONTROL MESSAGE is sent to the NIU from the INA to control several aspects of the upstream transmission. This includes stopping upstream transmission, re-enabling transmission from a NIU or group of NIU's and rapidly changing the upstream frequency being used by a NIU or group of NIU's. To identify a group of NIU's for switching frequencies, the TRANSMISSION CONTROL MESSAGE is sent in broadcast mode with the Old_Downstream_Frequency included in the message. When broadcast with the Old_Downstream_Frequency, the NIU shall compare its current frequency value to Old_Downstream_Frequency. When equal, the NIU shall switch to the new frequency specified in the message. When unequal, the NIU shall ignore the new frequency and remain on its current channel. A detailed description of the transmission control process, including state diagrams and time outs, is given in Annex A. ETSI 91 ETSI EN 301 199 V1.2.1 (1999-06) Table 44: Transmission Control Message structure Transmission_Control_Message (){ Bits Bytes Bit Number / Description Transmission_Control_Field 1 Reserved 1 7 Change_Timeouts 1 6: {no, yes} Switch_Downstream_IB_Frequency 1 5: {no, yes} Stop_Upstream_Transmission 1 4: {no, yes} Start_Upstream_Transmission 1 3: {no, yes} Old_Frequency_Included 1 2: {no, yes} Switch_Downstream_OOB_Frequency 1 1: {no, yes} Switch_Upstream_Frequency 1 0: {no, yes} if (Transmission_Control_Field &= Switch_Upstream_Frequency && Old_Frequency_Included){ Old_Upstream_Frequency (32) (4) } if (Transmission_Control_Field &= Switch_Upstream_Frequency){ New_Upstream_Frequency (32) (4) (1) New_Upstream_Channel_Number (3) 7..5 Reserved (2) 4..3 Upstream_Rate (3) 2..0 (1) MAC_Flag_Set (5) 7..3 Reserved (3) 2..0 } if (Transmission_Control_Field &= Switch_Downstream_OOB_Frequency && Old_Frequency_Included){ Old_Downstream__OOB_Frequency (32) (4) } if (Transmission_Control_Field &= Switch_Downstream_OOB_Frequency){ New_Downstream_OOB_Frequency (32) (4) Downstream_Type (8) (1) } if (Transmission_Control_Field &= Switch_Downstream_IB_Frequency && Old_Frequency_Included){ Old_Downstream__IB_Frequency (32) (4) } if (Transmission_Control_Field &= Switch_Downstream_IB_Frequency){ New_Downstream_IB_Frequency (32) (4) } if (Transmission_Control_Field &= Change_Timeouts){ Number_of_Timeouts (8) (1) for (I=0; I TRANSMISSION CONTROL MESSAGE with the start_upstream_transmission bit set. Old Upstream Frequency Old_Upstream_Frequency is a 32-bit unsigned integer representing the frequency that should be used by the NIU to compare with its current frequency to determine if a change in channel is required. New Upstream Frequency New_Upstream_Frequency is a 32-bit unsigned integer representing the reassigned upstream carrier centre frequency. The unit of measure is Hz. New_Upstream_Channel_Number is a 3-bit unsigned integer which identifies the new logical channel (denoted by "c") assigned to the NIU/STB. See subclause 5.3.2.1 for the use of this parameter. Upstream_Rate is an 3-bit enumerated byte indicating the upstream transmission bit rate for the upstream connection. {reserved, reserved, Upstream_3,088 M, 3...7 reserved} MAC_Flag_Set is a 5-bit field representing the first MAC Flag set assigned to the logical channel. A downstream channel contains information for each of its associated upstream channel. This information is contained within structures known as MAC Flag Sets represented by either 24 bits (denoted b0...b23) or by 3 bytes (denoted Rxa, Rxb, Rxc). This information is uniquely assigned to a given upstream channel. See subclauses 5.3.1.3 and 5.3.2.1 for the use of this parameter. Old Downstream OOB Frequency Old_Downstream_OOB_Frequency is a 32-bit unsigned integer representing the frequency that should be used by the NIU to compare with its current frequency to determine if a change in channel is required. New Downstream OOB Frequency New_Downstream_OOB_Frequency is a 32-bit unsigned integer representing the reassigned downstream OOB carrier centre frequency. The unit of measure is Hz. DownStream_Type is an 8-bit enumerated type indicating the modulation format for the down stream connection. {reserved, reserved, QPSK_3,088, 3...255 reserved} Old Downstream IB Frequency Old_Downstream_IB_Frequency is a 32-bit unsigned integer representing the frequency that should be used by the NIU to compare with its current frequency to determine if a change in channel is required. ETSI 93 ETSI EN 301 199 V1.2.1 (1999-06) New Downstream IB Frequency New_Downstream_IB_Frequency is a 32-bit unsigned integer representing the reassigned downstream IB carrier centre frequency. The unit of measure is Hz. Number_of_Timeouts Number_of_Timeouts is a 8-bit unsigned integer which identifies the number of timeout codes and values included in the message. Code Code is a 8-bit unsigned integer which identifies the timeout or group of timeouts (according to Table 21, and Table 51) for which the following value is given. Value Value is a 8-bit unsigned integer which gives the value for the timeout or group of timeouts identified by the preceding code. The unit of measure is 100 ms. The value shall be between the Min Value and the Max Value given in Table 21, and Table 51 (if specified). If no values are given in the Default Configuration Message, the default values apply. Values for single timeouts overwrite values for groups of timeouts for the specified timeout. Link Management Response Message (Upstream contention or reserved) The LINK MANAGEMENT RESPONSE MESSAGE is sent by the NIU to the INA to indicate reception and processing of the previously sent Link Management Message. The format of the message is shown in the following table. Table 45: Link Management Acknowledge Message structure Link_Management_Acknowledge (){ Bits Bytes Bit Number /Description Link_Management_Msg_Number 16 2 } Link Management Message Number Link_Management_Msg_Number is a 16-bit unsigned integer representing the previously received link management message. The valid values for Link_Management_Msg_Number are shown in the following table. Table 46: Link Management Message Number Message Name Link_Management_Msg_Number Transmission Control Message Transmission Control Message Type Value Reprovision Message Reprovision Message Type Value Status Request Message (Downstream Singlecast) The STATUS REQUEST message is sent by the INA to the NIU to retrieve information about the NIU's health, connection information and error states. The INA can request either the address parameters, error information, connection parameters or physical layer parameters from the NIU. The INA can only request one parameter type at a time to a particular NIU. A detailed description of the status request process, including state diagrams and time outs, is given in Annex A. Table 47: Status Request Message structure Status_Request (){ Bits Bytes Bit Number / Description Status_Control_Field 1 Reserved 4 4...7 Status_Type 4 0..3: {enum type} } ETSI 94 ETSI EN 301 199 V1.2.1 (1999-06) Status Control Field Status_Control_Field is a 3-bit enumerated type that indicates the status information the NIU should return enum Status_Control_Field {Address_Params, Error_Params, Connection_Params, Physical_Layer_Params, reserved 4...7}; Status Response Message (Upstream contention or reserved) The STATUS RESPONSE MESSAGE is sent by the NIU in response to the STATUS REQUEST MESSAGE issued by the INA. The contents of the information provided in this message will vary depending on the request made by the INA and the state of the NIU. The message shall be dissociated into separate messages if the resulting length of the message exceeds 40 bytes, even if fragmentation of messages is supported. ETSI 95 ETSI EN 301 199 V1.2.1 (1999-06) Table 48: Status Response Message Structure Status_Response (){ Bits Bytes Bit Number / Description NIU_Status 4 Reserved 29 31..3 Network_Address_Registered 1 2 Connection_Established 1 1 Calibration_Operation_Complete 1 0 Response_Fields_Included 1 Reserved 4 4..7: Address_Params_Included 1 3: {no, yes} Error_Information_Included 1 2: {no, yes} Connection_Params_Included 1 1: {no, yes} Physical_Layer_Params_Included 1 0: {no, yes} if (Response_Fields_Included &= Address_Params_Included){ NSAP_Address (160) (20) MAC_Address (48) (6) } if (Response_Fields_Included &= Error_Information_Included){ Number_Error_Codes_Included (8) (1) for(i=0;i Reservation_Request messages. Only contention access is allowed for minislots. Minislots can be utilized in both in-band signalled and out-of-band signalled systems. The in-band signalling uses the same control fields as the out-of-band signalling inside the MAC flags, and the MAC messages are the same for both in-band and out-of-band signalling case. The phrase minislot refers to a physical frame structure of the upstream channel. The 64 byte upstream slots are called ATM slots. ETSI 98 ETSI EN 301 199 V1.2.1 (1999-06) 5.6.2 Minislot framing structure In case minislots are used, the upstream slot structure is sub-divided into three 21 byte long mini-slots. Each of these minislots can be sent by different user terminals. The upstream channel can support a mixture of ATM slots and minislots. The format of the minislot is shown in the following figure. It contains a 4 byte Unique Word (the minislot UW and the ATM slot UW will differ to enable simple decoding of the ATM slots and the minislots by the PHY), a single byte Start field, a 16 byte payload and a single byte guard band. 64 bytes ATM Slot Structure Minislot Minislot Minislot GB 1 21 bytes Figure 36: Minislot Framing Structure For the structure of the minislot itself see subclause 5.5.2.6. 5.6.3 Contention resolution for minislots Minislots may carry the Reservation Request MAC message. The message is sent in a contention based minislot. In the case of collision, the resolution is carried out according to a INA controlled ternary splitting algorithm (see Figure 37). All necessary information is transmitted in the minislot feedback and minislot allocation sections of the Reservation_Grant_Message. If Stack_Entry is not set a NIU may enter the contention process only when the Allocation_Collision_Number is equal to zero. the number of minislots with Allocation_Collision_Number equal to 0. If Stack_Entry is set, the NIU may enter the contention resolution in any of the contention based minislots, independent of the value of Allocation_Collision_Number. Furthermore both cases the random number for the minislot selection in the range between 0 and Entry_Spreading shall be in the window from 0 to 2 before sending the request. If Stack_Entry is set, the NIU may enter the contention resolution in any of the contention based minislots, independent of the value of the Feedback_Collision_Number equals to 0xFF and 0xFE for idle and successful transmission, respectively. All other values of the Collision_Number are numbered as collisions and used to select the retransmission minislots: the NIU shall retransmit in a minislot having an Allocation_Collision_Number equal to Collision_Number The retransmission of the collided request takes place in a minislot that is randomly selected among a the group of three minislots with the corresponding Allocation_Collision_Number. ETSI 99 ETSI EN 301 199 V1.2.1 (1999-06) from reservation state diagram E4 (send reservation request) Contention_Start Do If (.not.Stack_Entry) Feedback_Collision_Number =0xFF wait for group of minislots with Allocation_Collision_Number=0 (error: empty slot) Else wait for group of minislots R = random (Entry_Spreading) Until R < 3 transmit request in minislot number R Feedback_Collision_Number =0xFE wait for feedback / (successful transmission) reservation grant Feedback_Collision_Number < 0xFE (collision) exit wait for group of minislots with Allocation_Collision_Number = Feedback_Collision_Number transmit requuest in minislot number random(3) Figure 37: Ternary Splitting Algorithm 5.7 Security (optional) The security solution consists of two separate sub-systems: • A new set of MAC messages used for authentication and key-agreement between INA and NIU. These messages are used only during connection-set-up. • On-the-fly encryption and decryption of payload data streams passed between INA and NIU. When a connection is being set-up, before payload data is transferred, one of three new request/response MAC message-pairs is used to generate a session key specific to the payload stream associated with the connection. The session key is a shared secret between the INA and the NIU: even if every MAC message is intercepted, the cryptographic properties of the protocol ensure that an eavesdropper cannot determine the session key value. This is achieved by using a public-key protocol, which requires no up-front shared secret, or a simpler protocol based on a long-term shared secret between INA and NIU called a cookie. The cookie is 160 bits long. It is also used for authenticating the NIU to the INA during connection-set-up. Each NIU will store its own cookie in non-volatile storage, whereas the INA will maintain a data-base of the cookie values of the NIUs on its network. Cookie values will be updated occasionally as dictated by security policy, but they are less vulnerable than session keys: a successful brute-force attack on a session key reveals nothing about the cookie value, nor any other session key. The new MAC messages also implement a defence against clones: a NIUs that is a physical copy of an existing NIU and attempts to operate on the network under the cloned identity (when the cloned NIU itself is not registered on the network). The anti-cloning measure is a simple non-volatile 8-bit counter that is incremented synchronously at the INA and NIU over time: if a clone NIU engages in traffic with the INA, this will be detected the next time the cloned NIU connects because the counter value will be out of synchronization. If the clone attempts to operate concurrently with the cloned unit, there will be an immediate break-down of functionality for both units, due to confusion within the MAC protocol. This amounts to a denial-of-service attack, and the INA should be prepared for this kind of protocol failure. ETSI 100 ETSI EN 301 199 V1.2.1 (1999-06) 5.7.1 Cryptographic primitives The key exchange protocols and data stream encryption is based on a set of well-established primitive cryptographic functions. The functions and their associated key sizes can be changed in the future, in case crypt-analytic or brute-force attacks become a realistic threat. The specific set of functions and key sizes are negotiated between INA and NIU at sign-on time. The functions supported at the present time are Diffie-Hellman, HMAC-SHA1, and DES. Check current cryptographic literature for any updates regarding their security and use. The following sections give a brief overview of the cryptographic primitives, and details on how they are used in the protocol. Later sections describe the exact field layout of the new MAC messages. The protocol parameters are described in terms of byte strings, where concatenation is denoted by the ~ operator. Integer quantities are represented as base-256 byte strings. Big-endian byte-ordering is used, that is, the most significant byte comes first. If necessary to reach a fixed length, the string is padded with zeros at the most significant end. 5.7.1.1 Public key exchange A public key exchange primitive is used to allow the INA and NIU to agree on a secret, although communicating in public. The Diffie-Hellman scheme is based on unsigned integer arithmetic and works as follows (A denotes exponentiation): The INA chooses two public values, a large prime number P, and a (small) number J which is a generator modulo P (that is, JAD PRG P will generate all number from  to P for varying D). The INA also chooses a secret number [  P, and sends the following three values to the NIU: P J ; JA[ PRG P. The NIU chooses a secret value \  P, and responds to the INA with the value < JA\ PRG P. The NIU now calculates V ;A\ PRG P JA[ A\ PRG P JA [ \ PRG P, whereas the INA calculates Security Sign-On and Security Sign-On Response messages (see subclauses 5.7.9.1 and 5.7.9.2) which are exchanged immediately prior to the Initialization Complete message. A failure during this stage of the protocol causes the INA to revert to non-secure interaction with the NIU. • The security context of a secured payload stream is established when the underlying MAC connection is created, before any stream data is transmitted. One session key is agreed, and the cookie and/or clone counter values may be updated as part of the exchange. The key exchange consists of Main/Quick/Explicit Key Exchange and Main/Quick/Explicit Key Exchange Response messages (see subclauses 5.7.9.3 to 5.7.9.8) which are exchanged immediately prior to the Connect Confirm message. A failure during this stage of the protocol causes the connection-set-up operation to fail. ETSI 105 ETSI EN 301 199 V1.2.1 (1999-06) • After a connection is in use, each session key of the security context of the payload stream can be updated on-the-fly, that is, without re-establishing the underlying connection, and without interrupting payload data traffic. The cookie and/or clone counter values cannot be updated as part of the exchange. A new session key is negotiated using the same MAC messages used during connection-set-up. There is no Connect Confirm message. A failure during this stage of the protocol causes the connection to be dropped. While a session key of the security context is being updated for a particular connection, payload stream data traffic should be encrypted using the other session key or not at all. Once the key exchange is complete, the INA can start using it for subsequent downstream traffic, thereby directing the NIU to use it for upstream traffic. All three variants of key exchange messages authenticate the NIU based on the existing cookie value. They also perform the clone detection counter check, and optionally increment the clone counter. Only MKE can update the cookie. The security MAC message flow is naturally serialized within the context of the particular connection that is being set-up. But, in as far as multiple connections are being established concurrently, there can also be multiple concurrent key exchanges whose messages are interleaved. The NIU is free to complete outstanding key exchanges on separate connections in any order it chooses 5.7.8 Persistent state variables To facilitate authentication, key exchange, and clone detection, the NIU has a set of state variables whose values are retained across registrations and power cycles: Table 50: Persistent NIU variables Name Function Size Cookie authentication cookie 160 bits Cookie_SN cookie sequence number 1 bit Clone_Counter clone detection counter 8 bits Clone_Counter_SN clone counter sequence number 1 bit The sequence numbers are used to ensure that the INA and NIU can stay synchronized even in case the NIU drops off the net in the middle of a protocol exchange. 5.7.8.1 Guaranteed delivery Within the set-up protocol for a MAC connection, the INA will ensure that a protocol exchange is complete before proceeding. If it doesn't receive a response MAC message within a given time-interval, it will re-transmit the original message unchanged. The NIU will do likewise in situations where it requires a response. If the number of re-transmissions exceeds three, the protocol fails. Due to race conditions, superfluous re-transmissions may be generated by both INA and NIU. They shall discard such messages after the first message has in fact been received. If the NIU is not ready to respond within the specified time-out, it can send Wait messages (see subclause 5.7.9.9) to extend the time it has available to generate a proper response. Upon receiving the wait message, the INA will restart its timer and reset the retry count. The protocol time-out values can be set by the Default Configuration Message, otherwise the following default values apply: Table 51: Protocol time-out values Code Protocol stage Default Value 0xD Security Sign-On 90 0xE Main Key Exchange 600 0xF Quick Key Exchange 300 Explicit Key Exchange ETSI 106 ETSI EN 301 199 V1.2.1 (1999-06) Time-out values are: Table 52: Protocol time-out values Protocol stage timeout value Security Sign-On 100 ms Main Key Exchange 400 ms Quick Key Exchange 200 ms Explicit Key Exchange 200 ms The Unit for the timeouts is ms. 5.7.9 Security MAC Messages 5.7.9.1 Security Sign-On (Single-cast Downstream) As part of the registration process when a NIU attaches to the network, the INA and NIU will negotiate the specific set of cryptographic algorithms and parameters used in the key exchange protocols and for payload encryption. The selections are global, and apply to all subsequent security exchanges for as long as the NIU is registered on the network. The selections affect the layout of the subsequent key exchange messages, since they have fields that vary in size according to the choice of algorithms and parameters. The INA indicates which algorithms and parameters it supports by setting the appropriate bits in the Security Sign-On message. There are four classes of algorithms, and the INA will set one or more bits in each of the four fields to indicate which specific choices it supports: Table 53: Security Sign-On message structure Security_Sign-On (){ Bits Bytes Bit Number / Description Parameter bytes Public_Key_Alg 1 Public key algorithm choices: Ppka: PKA_Reserved 7 7..1: Reserved, shall be 0 64 PKA_DH_512 1 0: (yes/no) Diffie-Hellman, 512 bits Hash_Alg 1 Hash algorithm choices: Pha: HA_Reserved 7 7..1: Reserved, shall be 0 20 HA_HMACSHA1 1 0: (yes/no) HMAC-SHA1 Encryption_Alg 1 Encryption algorithm choices: Pea: EA_Reserved 6 7..2: Reserved, shall be 0 8 EA_DES_56 1 1: (yes/no) DES, 56-bit key EA_DES_40 1 0: (yes/no) DES, 40-bit key 8 Nonce_Size 1 Nonce size choices: Pns: NS_Reserved NS_64 7 7..1: Reserved, shall be 0 8 1 0: (yes/no) 8 random bytes Reserved 32 4 Reserved for future use, shall be 0 } If the security option is supported, the minimum subset to support is PKA_DH_512, HA_HMACSHA1, EA_DES_40, and NS_64. EA_DES_56 is optional. ETSI 107 ETSI EN 301 199 V1.2.1 (1999-06) 5.7.9.2 Security Sign-On Response (Upstream) In its security sign-on response, the NIU indicates which specific algorithms and parameters to use. It does so by choosing one of the suggestions offered by the INA within each of the four classes. The fields of the response message have the same definition as the message from the INA, except that exactly one bit will be set in each field. If the NIU is unable to support any of the suggested algorithms for any class, it shall return an all-zero field value, and the INA will revert to non-secure communication or re-issue the Security Sign-On message with different choices. Table 54: Security Sign-On Response message structure Security_Sign-On_Response (){ Bits Bytes Bit Number / Description Parameter bytes Public_Key_Alg 1 Public key algorithm choices: Ppka: PKA_Reserved 7 7..1: Reserved, shall be 0 64 PKA_DH_512 1 0: (yes/no) Diffie-Hellman, 512 bits Hash_Alg 1 Hash algorithm choices: Pha: HA_Reserved 7 7..1: Reserved, shall be 0 20 HA_HMACSHA1 1 0: (yes/no) HMAC-SHA1 Encryption_Alg 1 Encryption algorithm choices: Pea: EA_Reserved 6 7..2: Reserved, shall be 0 8 EA_DES_56 1 1: (yes/no) DES, 56-bit key EA_DES_40 1 0: (yes/no) DES, 40-bit key 8 Nonce_Size 1 Nonce size choices: Pns: NS_Reserved 7 7..1: Reserved, shall be 0 8 NS_64 1 0: (yes/no) 8 random bytes Reserved 32 4 Reserved for future use, shall be 0 } 5.7.9.3 Main Key Exchange (Single-cast Downstream) The Main Key Exchange message is used to start a cookie-independent key exchange with the NIU, and also instructs the NIU whether to update its cookie value and clone counter value. ETSI 108 ETSI EN 301 199 V1.2.1 (1999-06) Table 55: Main Key Exchange message structure Main_Key_Exchange (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 1 Reserved 4 7..4: shall be 0 FL_Initializing 1 3: (yes/no) first ever key exchange FL_Update_Cookie 1 2: (yes/no) make new cookie value FL_Update_Counter 1 1: (yes/no) increment clone counter FL_Session_Key 1 0: select session key 0 or 1 Reserved 8 1 Reserved for future use, shall be 0 Nonce Pns Random string nonce1 DH_Modulus Ppka Diffie-Hellman modulus m DH_Generator Ppka Diffie-Hellman generator g DH_Public_X Ppka Diffie-Hellman public value X } The FL_Session_Key bit specifies which session key of the security context to update. If the FL_Update_Counter bit is set, it instructs the NIU to increment its clone detection counter. If the FL_Update_Cookie bit is set, it instructs the NIU to generate a new cookie value to be used for future authentication and key exchanges, and to reset the clone detection counter to zero. Any updates to the cookie, clone counter, or their associated sequence number bits do not take effect until the following Connect Confirm message is received by the NIU. If the FL_Initializing bit is set, it tells the NIU that the Authenticator field in the response will be ignored. The sizes of the multi-byte fields are determined by the parameters of the algorithms selected during security sign-on (see subclause 5.7.9.1). The INA will use its own private Diffie-Hellman value, [, together with the fields of the response message from the NIU to derive the new session key value, as well as any new value for the cookie (see subclause 5.7.2). 5.7.9.4 Main Key Exchange Response (Upstream) The Main Key Exchange Response message authenticates the NIU and completes the cookie-independent key exchange with the INA. It also contains the current value of the clone detection counter. Table 56: Main Key Exchange Response message structure Main_Key_Exchange_Re-sponse (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 1 Reserved FL_Cookie_SN 6 7..2: shall be 0 FL_Counter_SN 1 1: cookie sequence number 1 0: clone counter sequence number Clone_Counter 8 1 Current clone counter value Nonce Pns Random string nonce2 Authenticator Pha Authentication value auth DH_Public_Y Ppka Diffie-Hellman public value Y } ETSI 109 ETSI EN 301 199 V1.2.1 (1999-06) The FL_Counter_SN bit is the current sequence number of the clone detection counter. The Clone_Counter field is the current value of the counter. A clone collision has been detected if the INA finds a mis-match from the expected value. The FL_Cookie_SN bit is the sequence number of the cookie used for authentication. If the FL_Update_Cookie bit was set by the INA, the NIU will generate a new cookie value and complement the cookie sequence number bit. It will also reset the clone counter value to zero and clear the clone counter sequence number bit. If the FL_Update_Counter bit was set by the INA, the NIU will increment the value of the clone counter (modulo 256) and complement the clone counter sequence number bit. Any updates to the cookie, clone counter, or their associated sequence number bits do not take effect, and shall not be committed to non-volatile storage, until the following Connect Confirm message is received by the NIU. The NIU uses its private Diffie-Hellman value, \, together with the message fields to derive the new session key value, as well as any new value for the cookie (see subclause 5.7.2). 5.7.9.5 Quick Key Exchange (Single-cast Downstream) The Quick Key Exchange message is used to start a cookie-dependent key exchange with the NIU, and also instructs the NIU whether to update its clone counter value. Table 57: Quick Key Exchange message structure Quick_Key_Exchange (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 8 1 Reserved FL_Update_Counter 6 7..2: shall be 0 FL_Session_Key 1 1: (yes/no) increment clone counter 1 0: select session key 0 or 1 Reserved 8 1 Reserved for future use, shall be 0 Nonce Pns Random string nonce1 } The FL_Session_Key bit specifies which session key of the security context to update. If the FL_Update_Counter bit is set, it instructs the NIU to increment its clone detection counter. The INA will use its knowledge of the cookie value together with the fields of the response message from the NIU to derive the session key value (see subclause 5.7.3). 5.7.9.6 Quick Key Exchange Response (Upstream) The Quick Key Exchange Response message authenticates the NIU and completes the cookie-dependent key exchange with the INA. It also contains the current value of the clone detection counter. ETSI 110 ETSI EN 301 199 V1.2.1 (1999-06) Table 58: Quick Key Exchange Response message structure Quick_Key_Exchange_Re-sponse (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 1 Reserved 6 7..2: shall be 0 FL_Cookie_SN 1 1: cookie sequence number FL_Counter_SN 1 0: clone counter sequence number Clone_Counter 8 1 Current clone counter value Nonce Pns Random string nonce2 Authenticator Pha Authentication value auth } The FL_Cookie_SN bit is the sequence number of the cookie used for authentication. The FL_Counter_SN bit is the current sequence number of the clone detection counter. The Clone_Counter field is the current value of the counter. A clone collision has been detected if the INA finds a mis-match from the expected value. If the FL_Update_Counter bit was set by the INA, the NIU will increment the value of the clone counter (modulo 256) and complement the clone counter sequence number bit. The updated values do not take effect, and shall not be committed to non- volatile storage, until the following Connect Confirm message is received by the NIU. The NIU uses the cookie value together with the message fields to derive the session key value (see subclause 5.7.3). 5.7.9.7 Explicit Key Exchange (Single-cast Downstream) The Explicit Key Exchange message is used to securely deliver an existing session key value to the NIU, and also instructs the NIU whether to update its clone counter value. Table 59: Explicit Key Exchange message structure Explicit_Key_Exchange (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 1 Reserved 6 7..2: shall be 0 FL_Update_Counter 1 1: (yes/no) increment clone counter FL_Session_Key 1 0: select session key 0 or 1 Reserved 8 1 Reserved for future use, shall be 0 Nonce Pns Random string nonce1 Encryptedkey Pea Encrypted session key } The FL_Session_Key bit specifies which session key of the security context to update. If the FL_Update_Counter bit is set, it instructs the NIU to increment its clone detection counter. The INA has used its knowledge of the cookie value to encrypt the session key value (see subclause 5.7.4). 5.7.9.8 Explicit Key Exchange Response (Upstream) The Explicit Key Exchange Response message authenticates the NIU and acknowledges receipt of the delivered key. It also contains the current value of the clone detection counter. ETSI 111 ETSI EN 301 199 V1.2.1 (1999-06) Table 60: Explicit Key Exchange Response message structure Explicit_Key_Exchange_Response (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Flags 1 Reserved 6 7..2: shall be 0 FL_Cookie_SN FL_Counter_SN 1 1: cookie sequence number 1 0: clone counter sequence number Clone_Counter 8 1 Current clone counter value Nonce Pns Random string nonce2 Authenticator Pha Authentication value auth } The FL_Cookie_SN bit is the sequence number of the cookie used for authentication and session key decryption. If the INA determines that it has used the wrong cookie for session key encryption it will re-issue the Explicit Key Exchange using the old cookie value. The FL_Counter_SN bit is the current sequence number of the clone detection counter. The Clone_Counter field is the current value of the counter. A clone collision has been detected if the INA finds a mis-match from the expected value. If the FL_Update_Counter bit was set by the INA, the NIU will increment the value of the clone counter (modulo 256) and complement the clone counter sequence number bit. The updated values do not take effect, and shall not be committed to non-volatile storage, until the following Connect Confirm message is received by the NIU. The NIU uses the cookie value together with the message fields to decrypt the session key value (see subclause 5.7.4). 5.7.9.9 Wait (Upstream) The Wait message is used by the NIU to extend the time the INA waits for a reply to a given message. Upon receiving it, the INA will reset its time-out value and retry count (see subclause 5.7.8.1). Table 61: Wait message structure Wait (){ Bits Bytes Bit Number / Description Connection_ID 32 4 MAC connection identifier Message_Type 8 1 Type of message from INA Reserved 8 1 Reserved for future use, shall be 0 } The Message_Type field is the message type value of the message received from the INA being processed. If the message is specific to a connection, the Connection_ID field identifies which; otherwise this field is zero. The NIU indicates that it is currently unable to send a reply to the message. 6 Interactive STB / Data Modem Mid Layer Protocol This clause describes the mid layers to be used when the present standard is used to implement Interactive STB respectively Data Modem applications. Three solutions are given for this application, Direct IP, Ethernet MAC bridging and PPP. Direct IP is mandatory for both INA and NIU, the other two solutions are optional. Interoperability testing will be performed only on Ethernet MAC bridging until 6 month after the ratification of this specification by ETSI. 6.1 Direct IP The goal of this subclause is to allow compatible and interoperable implementations for transmitting IP datagrams [16] over ATM AAL5 [13] and DVB Multiprotocol Encapsulation [3], as used by the present document for upstream and downstream transmission. ETSI 112 ETSI EN 301 199 V1.2.1 (1999-06) 6.1.1 Framing INA and NIU/STB shall support an MTU size of 1 500 Byte. 6.1.1.1 Upstream and OOB Downstream The IP datagram shall be carried as such in the payload of the AAL5 CPCS-PDU. This method is described in RFC 1483 [13] as VC based multiplexing for routed protocols and is generally also known as null encapsulation. 6.1.1.2 IB Downstream The IP datagram shall be carried as such in the DVB Multiprotocol Encapsulation sections of EN 301 192 [3], LLC_SNAP_flag is set to zero. 6.1.2 Addressing In upstream framing structure and in downstream out-of-band framing structure, the addressing of a specific NIU/STB is done with a VPI/VCI pair. At least one VPI/VCI pair is assigned per NIU/STB. The following VPI/VCI pairs are reserved: VPI / VCI Remark any / 0..0x1F reserved for ATM use 0 / 0x20 reserved for DAVIC use 0 / 0x21 reserved for DVB MAC messages 0 / 0x22 reserved for broadcast All other VPI/VCI pairs can be assigned by the INA for carrying IP traffic. The VPI/VCI is provided through the DVB MAC protocol. 6.1.2.1 IP Broadcast and Multicast from STB/NIU to INA All upstream IP broadcast and multicast packets shall be transmitted with an upstream VPI/VCI given in a MAC connect message. 6.1.2.2 IP Broadcast and Multicast from INA to STB/NIU IB downstream For IB downstream, IP broadcast and multicast shall be carried out according to EN 301 192 [3] as described below: IB downstream IP broadcast shall be transmitted with the broadcast MAC address FF:FF:FF:FF:FF:FF. An IP multicast group is joined according to the IGMP protocol [12]. Additionally, the INA may assign a new DVB MAC connection to the NIU/STB for that purpose, including a multicast MAC address. IB downstream multicast shall than be transmitted with that multicast MAC address. OOB downstream OOB downstream IP broadcast shall be transmitted with a VPI/VCI value of 0/0x22. An IP multicast group is joined according to the IGMP protocol [12]. Additionally, the INA may assign a new MAC connection to the NIU/STB for that purpose. QPSK downstream multicast shall than be transmitted with the VPI/VCI given in the corresponding MAC connect message. 6.1.3 IP Address Assignment After receiving the MAC Connect confirm message, the NIU/STB shall use either the BOOTP or the DHCP protocol according to RFC 951 [15] and to RFC 2131 [14] to get an IP address from the network, unless a fixed IP address was assigned to the NIU/STB by the operator and made known to the INA. All additional IP addresses of customer premises equipment connected to the NIU/STB shall be assigned through BOOTP or DHCP, unless fixed IP addresses have been assigned by the operator. Singlecast downstream traffic with a destination IP address not assigned through BOOTP, DHCP or the operator shall be discarded by the INA. Upstream traffic with a source host IP address not assigned through BOOTP, DHCP or the operator shall be discarded by the NIU/STB and by the INA. ETSI 113 ETSI EN 301 199 V1.2.1 (1999-06) 6.1.4 INA Interfaces (informative) t.b.d. 6.1.5 NIU/STB Interfaces (informative) t.b.d. 6.2 Ethernet MAC Bridging The goal of this subclause is to allow compatible and interoperable implementations for transmitting ISO 8802-3 Ethernet MAC frames [10] over ATM AAL5 [13] and DVB Multiprotocol Encapsulation [3], as used by the present standard for upstream and downstream transmission. 6.2.1 Framing 6.2.1.1 Upstream and OOB Downstream The Ethernet MAC frame shall be carried in the payload of the AAL5 CPCS-PDU as described in RFC 1483 [13] as LLC encapsulation for bridged Ethernet/802.3 PDUs, using PID 0x00-07 (LAN FCS is not transmitted). No padding bytes are inserted between the LLC/SNAP header and the Ethernet MAC frame. 6.2.1.2 IB Downstream The Ethernet MAC frame shall be carried in the payload of the DVB Multiprotocol Encapsulation sections as described in EN 301 192 [3], LLC_SNAP_flag is set to one. The value of the LLC/SNAP header is 0xAA-AA-03-00-80-C2-00-07. 6.2.2 Addressing In upstream framing structure and in downstream out-of-band framing structure, the addressing of a specific NIU/STB is done with a VPI/VCI pair. At least one VPI/VCI pair is assigned per NIU/STB. The following VPI/VCI pairs are reserved: VPI / VCI Remark any / 0..0x1F reserved for ATM use 0 / 0x20 reserved for DAVIC use 0 / 0x21 reserved for DVB MAC messages 0 / 0x22 reserved for broadcast All other VPI/VCI pairs can be assigned by the INA for carrying Ethernet traffic. The VPI/VCI is provided through the DVB MAC protocol. 6.3 PPP The goal of this subclause is to allow compatible and interoperable implementations for transmitting PPP packets over ATM AAL5 and DVB Multiprotocol Encapsulation [3], as used by the present standard for upstream and downstream transmission. 6.3.1 Framing The implementation shall be done according to the RFC2364, as mentioned in paragraph 5. 6.3.1.1 Upstream and OOB Downstream The PPP frame shall be carried as such in the payload of the AAL5 CPCS-PDU. This method is described in RFC 2364 [13] (Figure 1). The flag sequences, that delimit the beginning and the end of each frame, don't exist any more. The Asynchronous-Control-Character-Map (ACCM) is not negotiated. In this way, the stuffing procedure is no longer necessary. ETSI 114 ETSI EN 301 199 V1.2.1 (1999-06) 6.3.1.2 IB Downstream The PPP datagrams shall be carried in the payload of the DSM-CC sections as described in EN 301 192 [3] (DVB multiprotocol encapsulation) with the LLC_SNAP_flag set to one. The encapsulation of PPP into LLC/SNAP is defined in RFC2364 "PPP over AAL5" (with the NLPID value for PPP set to 0xCF). 6.3.2 Addressing In upstream framing structure and in downstream out-of-band framing structure, the addressing of a specific NIU/STB is done with a VPI/VCI pair. At least one VPI/VCI pair is assigned per NIU/STB. The following VPI/VCI pairs are reserved: VPI / VCI Remark any / 0..0x1F reserved for ATM use 0 / 0x20 reserved for DAVIC use 0 / 0x21 reserved for DVB MAC messages 0 / 0x22 reserved for broadcast All other VPI/VCI pairs can be assigned by the INA for carrying PPP traffic. Each PPP connection will be associated to one VPI/VCI provided through the MAC DVB RC protocol. 6.3.3 IP Address Assignment After receiving the MAC Connect confirm message, the NIU/STB uses IPCP protocol included in the PPP protocol, according to RFC 1332 to get an IP address from the network. The PPP protocol supports the case of a fixed IP address assigned to the STB/NIU. In the case a fixed IP address has been assigned to the NIU/STB by the operator, the IPCP protocol shall be used to make this IP address known to the INA. The PPP IPCP Configure-Request of the NIU/STB states which IP-address is used. The INA can provide an(other) IP address by making this option, and returning a valid IP-address. The NIU/STB shall use this IP address even in the case, the NIU/STB has a fixed one. 6.3.4 Additional IP addresses In the case the NIU/STB is also connected to customer premises equipment by a LAN, one of the following IP address assignment schemes shall be implemented: 1) the LAN has its own IP subnet address and subnet mask, in this case the NIU/STB acts like a router i.e. the IP subnet address and subnet mask of the LAN is completely independent of the INA; or 2) BOOTP/DHCP messages from the LAN are sent transparently through the PPP link to a server at the INA side. Singlecast downstream traffic with a destination IP address not assigned through PPP or BOOTP/DHCP shall be discarded by the INA. Upstream traffic with a source host IP address not assigned PPP or BOOTP/DHCP shall be discarded by the NIU/STB and by the INA. 6.3.5 Security The PAP or CHAP protocols will supply authentication and authorization mechanisms both included in PPP. 6.3.6 INA Interfaces (informative) t.b.d. 6.3.7 NIU/STB Interfaces (informative) t.b.d. ETSI 115 ETSI EN 301 199 V1.2.1 (1999-06) Annex A (informative): MAC State Transitions and Time Outs A.1 Ranging and Calibration Figure A.1 describes the ranging and calibration procedure in detail. ETSI 116 ETSI EN 301 199 V1.2.1 (1999-06) Initial E1: Power Up Wait for Provision Msg T1 E2: TO E3: Provision Msg Wait for Default Configuration T2 Msg E4: TO E5: Default Configuration Msg Wait for Sign-On T3 Request Msg E6: Sign-On Msg && addres != OK E8: Sign-On Request Msg && addres == OK E7: TO Wait for Random T4 Time E9: TO Wait for Ranging and Power Calibration Msg T5 or Initialisation Complete Msg E10: Ranging and Power Calibration Msg E13: TO && Power < MAX (E12: TO && Power >= MAX) or Initialisation Complete Msg with Completion_Status_Field != 0 E11: Initialisation Complete Msg with Completion_Status_Field = 0 Calibration_Oper T6 ation_Complete E15: TO E14: Ranging and Power Calibration Msg E16: MAC message sent upstream Figure A.1: State Diagram for Ranging and Calibration ETSI 117 ETSI EN 301 199 V1.2.1 (1999-06) The boxes represent states, state-transitions are represented by arrows. State-transitions are triggered by events, denoted by: "Ex: ". Triggers are either the reception of MAC-messages or Time-Outs. An event can lead to a state-transition depending on a condition, this is denoted by "Ex: && . A time-out timer runs in all the states. The values of these time-out counters are denoted by Tx. On the following pages the events are accompanied by actions that are performed by the state machine during the state transition. Some actions are performed only under a certain condition. To make this clear, "if then else" constructions are used. E1 Power up: Tune to any downstream channel (re)set timeout to T1 E2 Time Out received: Tune to next downstream channel (re)set timeout to T1 E3 Provision Msg received: IF current DS freq. != provision Freq. Tune provision channel (re)set timeout to T2 E4 Time Out received: Do nothing (re)set timeout to T1 E5 Default Configuration Msg received: Tune to service channel TimeOffset = Absolute_Time_Offset Output_Power_Level = MIN_Power_Level Power_Retry_Count = 0 Sign-On_Retry_Count = 0 (re)set timeout to T3 E6 Sign-On Msg && addres != OK: Do nothing (re)set timeout to T3 E7 Time Out received: Do nothing (re)set timeout to T1 E8 Sign-On Msg && addres == OK: Sign-On_Retry_Count = min (Sign-On_Retry_Count+1, 255) (re)set timeout to T4 E9 Time Out received: Send Sign-On Response Msg in ranging area (re)set timeout to T5 E10 Ranging and Power Calibration Msg: Time_Offset = Time_Offset + Time_Offset_Value Output_Power_Level = Output_Power_Level + Power_Control_Setting x 0,5 dB IF Ranging_Slot_Included send Ranging and Power Calibration Response Msg on Ranging_Slot_Number ELSE send Ranging and Power Calibration Response Msg in ranging area (re)set timeout to T5 E11 Initialization Complete Msg with Completion_Status_Field = 0: (re)set timeout to T6 ETSI 118 ETSI EN 301 199 V1.2.1 (1999-06) E12 (Time Out received && Power >= MAX) or Initialization Complete Msg with Completion_Status_Field != 0: Do nothing (re)set timeout to T1 E13 Time Out received && Power < MAX: Power_Retry_Count++ IF Power_Retry_Count < Sign_On_Incr_Pwr_Retry_Count Do Nothing ELIF Tuned to Backup Service Channel Tune to Service Channel Output_Power_Level = min (O utput_Power_Level + x dB, MAX_Power_Level) Power_Retry_Count = 0 ELIF Service Channel != Backup Service Channel (x ∈ [0,5...2]) Tune to Backup Service Channel Power_Retry_Count = 0 ELSE Output_Power_Level = min (Output_Power_Level + x dB, MAX_Power_Level) Power_Retry_Count = 0 (re)set timeout to T3 (x ∈ [0,5...2]) E14 Ranging and Power Calibration Msg: Absolute_Time_Offset = Absolute_Time_Offset + Time_Offset_Value Output_Power_Level = Output_Power_Level + Power_Control_Setting x 0,5 dB IF Ranging_Slot_Included send Ranging and Power Calibration Response Msg on Ranging_Slot_Number ELSE send Ranging and Power Calibration Response Msg in ranging area (re)set timeout to T6 E15 Time Out received Send Idle Mgs (re)set timeout to T6 E16 MAC message sent upstream (re)set timeout to T6 Table A.1 links the timeout of the State Transition Diagram to the timeouts. Table A.1: TimeOuts NIU SignOn STD Timeout Description Code (see Def. Conf. Msg.) T1 Provision Interval 0x31fixed 900 ms T2 Default Configuration Interval 0x 32 T3 Sign-On Message Interval 0x 332 T4 Random ( ResponseCollectionTimeWindow ) see Sign on Requ. Msg. T5 Sign On Response -> Rang. and Power Calibr. 0x3 Sign On Resp. -> Initial. Complete Rang. and Power Calibr. Resp. -> Rang. and Poer Cal. Rang. and Power Calibr. Resp. -> Initial. Complete T6 Idle Interval see Def. Conf. Msg. ETSI 119 ETSI EN 301 199 V1.2.1 (1999-06) A.2 Connection Establishment Two cases of connection establishment exist: connection establishment of the 1st or default connection, and connection establishment of additional connections after the default connection has been successfully established. If the STB detects the continuous loss of carrier or framing for longer than LofTimeout, then the STB will consider all connections released and will go to the Wait for Login state (T0?). Default Connection Establishment This procedure is started after a successful Sign-On and Calibration procedure. A special case exists when the STB loses the Initialization Complete Message but receives a Connect Message. In this special case, the STB shall proceed as if the Initialization Complete Message had been received. E1, From Sign-On, ICM status = 0 DCE 1 E4, From Sign-On, (re)Start NiuConnectTimeout E2, NiuConnectTimeout, go to Hunt (T1) Receive Connect Message, Lost ICM E3, Receive Connect Message DCE 3 DCE 2 (re)Start NiuConnectTimeout Parse Connect Message E5, US freq changed, go to Sign-On (T3)* E6, From Sign-On, New US Freq, ICM status = 0 DCE 4 E7, NiuConnectConfirmTimeout DCE 5 Send Connect Response (re)Start NiuConnectTimeout Start NiuConnectConfirmTimeout E8, NiuConnectTimeout DCE 6 Stop NiuConnectConfirmTimeout Go to Hunt (T1) * When entering Sign-On E9, Receive Connect Confirm Message w/ correct Connection_ID with NiuConnectTimeout running, if NiuConnectTimeout DCE 7 expires, then go to Hunt Stop NiuConnectTimeout Stop NiuConnectConfirmTimeout Default Connection is established MAC State = RUNNING Subsequent Connection Establishment This procedure can be entered only when the STB has at least one operating (i.e. not STOPPED via a TCM) connection. ETSI 120 ETSI EN 301 199 V1.2.1 (1999-06) E1, Receive Subsequent Connect Message SCE 1 Parse Connect Message E2, Invalid Connect Message*, Start NiuConnectTimeout Stop NiuConnectTimeout, exit SCE2 E3, NiuConnectConfirmTimeout Send Connect Response Start NiuConnectConfirmTimeout E4, NiuConnectTimeout, Stop NiuConnectConfirmTimeout, exit E5, Receive Connect Confirm Message w/ correct Connection_ID SCE3 Stop NiuConnectTimeout Stop NiuConnectConfirmTimeout Subsequent Connection is established * Subsequent Connect Message Validity if (US frequency is different than the current US frequency) { message invalid } else if (Connect Message contains both an IB and OOB DS frequency) { message invalid } else if (Connect Message contains an IB freq and the STB currently has an open connection on a different IB freq) { message invalid } else if (Connect Message contains an OOB freq and the STB currently has an open connection on a different OOB freq) { message invalid } A.3 Connection Release The STB may release connections only when it has at least one operating (i.e. not STOPPED by TCM) connection. If the STB has its number of connections reduced to one connection then the remaining connection is considered the default connection. E1, Receive Connection Release Message CR 1 Parse message E2, STB has no operating connections, exit CR 2 STB sends a Connection Release Response Message for each valid connection. If any Connection_ID is unknown by the STB, then the STB shall send zero in the response message. If Number_of_Connections is zero, then the STB shall release all open connections. ETSI 121 ETSI EN 301 199 V1.2.1 (1999-06) A.4 Reservation Process The figure below gives a state diagram of the reservation process. The boxes represent states, state-transitions are represented by arrows. State-transitions are triggered by events, denoted by: "Ex:". Triggers are either the reception of MAC messages or time outs. An event can lead to a state-transition depending on a condition; this is denoted by "Ex:&&". A pending slot is defined as a slot for which no reservation request has been sent yet. A requested slot is defined as a slot for which a reservation request has already been sent, but which is not yet granted. No assigned reservation_id (*)(**) E2 : no more E1 : Reservation_Id Reservation_Id Assignment message One or more (**) Reservation_Ids assigned E3 : Reservation_Id Assignment message E5 : no more or Release Message pending slots E4 : slots required Wait for reservation grant T1 E6 : Reservation Grant && pending E7 : TO slots (*) "No assigned Reservation_id" State is to be linked to the state diagram of connection establishment process. (**) No Time-Out is associated to this state since when transition shall occur is not in the scope of the specification. E1 Reservation_Id Assignment message: If a "Reservation_Id assignment" message is received with a valid connection_id send a "Reservation_id response" message consider new parameters go to "One or more Reservation_Ids assigned" E2 No more reservation_Id: If a "Release" message closes the last connection with an assigned reservation_id, Delete all slots allocated in reservation region for this connection go to "No assigned reservation_id" state If a "Reprovisioning" message is received with "Delete_Reservation_IDs" bit set, Delete all slots allocated in reservation region go to "No assigned reservation_id" state ETSI 122 ETSI EN 301 199 V1.2.1 (1999-06) E3 "Reservation_Id Assignment" message or "Release" message If a "Release" message closes the connection with an assigned reservation_id (but not the last), Delete all slots allocated in reservation region for this connection Stay in same state If a "Reservation_Id assignment" message is received with a valid connection_id consider new parameters send a "Reservation_ID_Response" message Stay in same state E4 Reservation slots are required by the NIU: Send a "Reservation Request" message with reservation_id corresponding to the connection maintain count of pending slots and requested slots for this connection Set a timer to T1 (equal to "grant_protocol_timeout" associated to the reservation_id) Go to "Wait for reservation grant" state E5 Reservation Grant message granting all requested slots: if a "reservation grant" message grants all the previous requests (i.e. with "remaining_slot_count" field set to 0) and no pending slots Disable active timers Go to "One or more Reservation_IDs Reservation_ID assigned" state ETSI 123 ETSI EN 301 199 V1.2.1 (1999-06) E6 Reservation Grant message but requested slots still to be granted: if a "reservation grant" message grants previous requests (but not all or some with "remaining_slot_count" field different from 0) For connection with request not completely granted Set timer of the connection to T1 (equal to "grant_protocol_timeout" associated to the reservation_id) Update number of requested slots with "granted slot count" field If "remaining_slot_count" < 15 and (pending_slot_count != 0 or requested_slot_count != remaining_slot_count) Send a "Reservation Request" message with reservation_id corresponding to the connection maintain count of pending slots and requested slots for this connection For completely granted connection disable timer of the connection set number of requested slots to 0 for this connection If pending slots exist Send a "Reservation Request" message with reservation_id corresponding to the connection maintain count of pending slots and requested slots for this connection Set timer of the connection to T1 (function of "grant_protocol_timeout" associated to the reservation_id) If new slots are required for a connection, update number of pending slots. Stay in same status E7 Time Out received: If an active timer elapsed Send a reservation status request message for the associated connection Set timer of the connection to T1 (function of "grant_protocol_timeout" associated to the reservation_id) If new slots are required for a connection, update number of pending slots. Stay in same status Time-out T1 is dynamically set by the INA in the "Reservation_Id_Assignment" message (grant_protocol_timeout parameter). ETSI 124 ETSI EN 301 199 V1.2.1 (1999-06) A.5 Re-calibration The STB may be re-calibrate whenever it has at least one open (i.e. STOPPED or RUNNING) connection. E1, Receive Ranging and Power Calibration Message RE 1 Parse message E2, STB has no open connections, exit RE 2 STB adjusts transmission parameters within it’s capabilities (i.e. the STB can Tx power in excess of normative range). STB sends Ranging and Power Calibration Response Message with the actual parameters used. A.6 Reprovision Message The STB can be re-provisioned whenever it has at least one operating connection. E1, Receive Reprovision Message REP 1 E2, STB has no operating connections or message invalid, exit Parse message E3, New US frequency, go to Sign-On (T3) REP 2 E4, New US frequency, STB sends the Link Management Message from Sign-On, ICM status = 0 A.7 Transmission Control Message The Transmission Control Message (TCM) controls aspects of upstream and downstream transmission. The commands are sent to the STB in either broadcast or singlecast mode. The STB is in one of the following MAC states: • RUNNING, the STB has at least one operating connection; • STOPPED, the STB has received a TCM Stop Upstream Transmission command; • ERROR, the STB has received a ICM with non-zero Completion_Status_Field; and • NONE, the STB has no open connections. ETSI 125 ETSI EN 301 199 V1.2.1 (1999-06) E1, Receive Transmission Control Message TCM 1 E2, Invalid message *, exit Parse message TCM 2 E3, New US freq && MAC_State == RUNNING, Set new MAC_State**, go to Sign-On (T3) Process frequency changes E4, New US frequency TCM 3 from Sign-On, ICM status = 0 If MAC_State == RUNNING, then Send LMM * Invalid TCM Besides invalid parameter values, the received TCM will be considered invalid if (Start_Upstream_Transmission && Stop_Upstream_Transmission) or (Old_Frequency != CurrentFrequency) in which case the STB will ignore the message. ** new MAC state if (Start_Upstream_Transmission == 0 && Stop_Upstream_Transmission == 0) { New_MAC_State = Old_MAC_State } else if (Start_Upstream_Transmission == 0 && Stop_Upstream_Transmission == 1) { if (Old_MAC_State == ERROR) New_MAC_State = ERROR else New_MAC_State = STOPPED } else if (Start_Upstream_Transmission == 1 && Stop_Upstream_Transmission == 0) { If (Old_MAC_State == ERROR && Broadcast) New_MAC_State = ERROR else New_MAC_State = RUNNING } A.8 Status Request Message The STB can be queried for status whenever it has at least one operating connection. E1, Receive Status Request Message SR 1 E2, STB has no operating connections, exit Parse message SR 2 STB sends the Status Response Message(s) If the Status_Type is unknown by the STB, then it shall send the response with Response_Fields_Included set to zero. A.9 Idle Message The Idle Message is sent during periods of upstream MAC message inactivity that exceed a non-zero Idle_Interval by the STB whenever it has at least one operating connection. ETSI 126 ETSI EN 301 199 V1.2.1 (1999-06) Bibliography The following material, though not specifically referenced in the body of the present document (or not publicly available), gives supporting information. DVB-A008 (1995): "Commercial requirements for asymmetric interactive services supporting broadcast to the home with narrowband return channels". DAVIC 1.5 Specification: "DAVIC System Reference Model". EN 300 429: "Digital Video Broadcasting (DVB); Framing structure, channel coding and modulation for cable systems". ETSI 127 ETSI EN 301 199 V1.2.1 (1999-06) History Document history V1.1.1 November 1998 Publication V1.2.1 January 1999 One-step Approval Procedure OAP 9921: 1999-01-22 to 1999-05-21 V1.2.1 June 1999 Publication ISBN 2-7437-3115-X Dépôt légal : Juin 1999 ETSI