1、 ETSI TS 102 188-3 V1.1.2 (2004-07)Technical Specification Satellite Earth Stations and Systems (SES);Regenerative Satellite Mesh - A (RSM-A) air interface;Physical layer specification;Part 3: Channel codingETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 2 Reference RTS/SES-00205-3 Keywords air interface, b
2、roadband, IP, multimedia, satellite ETSI 650 Route des Lucioles F-06921 Sophia Antipolis Cedex - 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 but non lucratif enregistre la Sous-Prfecture de Grasse (06) N 7803/88 Important notice Individual
3、copies of the present document can be downloaded from: http:/www.etsi.org The present document may be made available in more than one electronic version or in print. In any case of existing or perceived difference in contents between such versions, the reference version is the Portable Document Form
4、at (PDF). In case of dispute, the reference shall be the printing on ETSI printers of the PDF version kept on a specific network drive within ETSI Secretariat. Users of the present document should be aware that the document may be subject to revision or change of status. Information on the current s
5、tatus of this and other ETSI documents is available at http:/portal.etsi.org/tb/status/status.asp If you find errors in the present document, send your comment to: editoretsi.org Copyright Notification No part may be reproduced except as authorized by written permission. The copyright and the forego
6、ing restriction extend to reproduction in all media. European Telecommunications Standards Institute 2004. All rights reserved. DECTTM, PLUGTESTSTM and UMTSTM are Trade Marks of ETSI registered for the benefit of its Members. TIPHONTMand the TIPHON logo are Trade Marks currently being registered by
7、ETSI for the benefit of its Members. 3GPPTM is a Trade Mark of ETSI registered for the benefit of its Members and of the 3GPP Organizational Partners. ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 3 Contents Intellectual Property Rights4 Foreword.4 1 Scope 5 2 References 5 3 Definitions and abbreviations.
8、5 3.1 Definitions5 3.2 Abbreviations .5 4 General .6 5 Uplink.6 5.1 Uplink code block structure6 5.2 Uplink data scrambling 7 5.3 Uplink Forward Error Correction processing.8 5.3.1 Uplink outer code .8 5.3.2 Uplink block interleaving .10 5.3.3 Uplink inner code .10 6 Downlink11 6.1 Downlink code blo
9、ck structure.11 6.2 Downlink data scrambling12 6.3 Downlink Forward Error Correction processing 13 6.3.1 Downlink outer code.13 6.3.2 Downlink block interleaving.15 6.3.3 Downlink inner code.15 Annex A (informative): Bibliography.18 History 19 ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 4 Intellectual P
10、roperty 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 ETSI SR 000 314: “Intellectual Property Rights (IPRs)
11、; Essential, or potentially Essential, IPRs notified to ETSI in respect of ETSI standards“, which is available from the ETSI Secretariat. Latest updates are available on the ETSI Web server (http:/webapp.etsi.org/IPR/home.asp). Pursuant to the ETSI IPR Policy, no investigation, including IPR searche
12、s, has been carried out by ETSI. No guarantee can be given as to the existence of other IPRs not referenced in ETSI 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 Technical Specification (TS) has been produced
13、by ETSI Technical Committee Satellite Earth Stations and Systems (SES). The present document is part 3 of a multi-part deliverable covering the BSM Regenerative Satellite Mesh - A (RSM-A) air interface; Physical layer specification, as identified below: Part 1: “General description“; Part 2: “Frame
14、structure“; Part 3: “Channel coding“; Part 4: “Modulation“; Part 5: “Radio transmission and reception“; Part 6: “Radio link control“; Part 7: “Synchronization“. ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 5 1 Scope The present document defines the channel coding structure used within the SES BSM Regener
15、ative Satellite Mesh - A (RSM-A) air interface family. It includes code block, scrambling, outer forward error correction encoding, interleaving, and inner forward error correction encoding process definition. 2 References Void. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the
16、 present document, the following terms and definitions apply: Network Operations Control Centre (NOCC): centre that controls the access of the satellite terminal to an IP network and also provides element management functions and control of the address resolution and resource management functionalit
17、y satellite payload: part of the satellite that provides air interface functions NOTE: The satellite payload operates as a packet switch that provides direct unicast and multicast communication between STs at the link layer. Satellite Terminal (ST): terminal installed in the user premises terrestria
18、l host: entity on which application level programs are running NOTE: It may be connected directly to the Satellite Terminal or through one or more networks. 3.2 Abbreviations For the purposes of the present document, the following abbreviations apply: FEC Forward Error Correction IP Internet Protoco
19、l LSB Least Significant Bit MSB Most Significant Bit NOCC Network Operations Control Centre PTP Point-To-Point RS Reed-Solomon RSM Regenerative Satellite Mesh SLC Satellite Link Control ST Satellite Terminal TDMA Time Division Multiple Access ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 6 4 General The f
20、unctions of the physical layer are different for the uplink and downlink. The major functions are illustrated in figure 4. UPLINK DOWNLINK Part 3: Channel coding Part 2: Frame structure Part 4: Modulation Part 5: Radio transmission and reception tn Part 7: Synchronization Block interleaving Inner co
21、ding (convolutional) Downlink burst building Downlink modulation (QPSK) ST receiver Scrambling Assemble packets into code blocks Outer coding (Reed-Solomon) No interleaving Inner coding (hamming) Uplink burst building Uplink modulation (OQPSK) Part6:Radio linkcontrolScrambling Timing and frequency c
22、ontrol ST transmitter Assemble packets into code blocks Outer coding (Reed-Solomon) Figure 4: Physical layer functions The present document describes the channel coding functions - this group of functions is highlighted in figure 4. The uplink channel coding is described in clause 5 and the downlink
23、 channel coding is described in clause 6. 5 Uplink 5.1 Uplink code block structure Uplink code blocks are the basic unit in the formation of an uplink TDMA burst. The number of code blocks constituting an uplink burst depends on the carrier mode. Uplink code blocks are formed with a set of user data
24、 packets and an access control field that have been processed with FEC to achieve acceptable packet error rates. ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 7 Uplink code blocks are generated as shown in figure 5.1. This is described in two stages: Assembly of an uncoded block containing two user data p
25、ackets plus an access control field. Forward Error Correction coding. The FEC on the uplink uses a set of two concatenated error correction codes, with no interleaving in between the codes. The outer code consists of a t=12 symbol error correcting (244,220) Reed-Solomon code followed by an inner sho
26、rtened Hamming (12,8) block code. Header 8 bytes User data 100 bytes Header 8 bytes User data 100 bytes + 2nd packet 1st packet Access control 4 bytes + Not scrambled Potentially scrambled 220 bytes Outer code Reed - Solomon (244,220) Inner code block (12,8) 244 bytes 366 bytes per code block Figure
27、 5.1: Uplink code block generation 5.2 Uplink data scrambling The ST shall scramble the information payload field of all packets (i.e. byte 8 through byte 107 of a 108-byte packet) except those destined only to the satellite, as defined in table 5.2. The destination type is specified in the destinat
28、ion type sub-field of the header satellite routing field as described in TS 102 189-2. The scrambling is performed on a packet-by-packet basis. Scrambling starts and stops at the beginning and ending of the information payload field, respectively. Table 5.2: Scrambling according to packet type Desti
29、nation type Scrambling Null packets Scrambled PTP or shaped-broadcast packets Scrambled Packet replication packets Scrambled Satellite terminated packets (except null packets) Not scrambled The scrambling sequence is generated by a LFSR with connection polynomial: ()151 XXXh += as illustrated in fig
30、ure 5.2, where the adders perform modulo-2 arithmetic. The scrambler is initialized at the beginning of every packet. The initial sequence is given by 110100101011001 (X0. X14). ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 8 1 2 3 4 15Input DataPN SequenceScrambled DataX14X0X1Figure 5.2: Uplink data scra
31、mbler 5.3 Uplink Forward Error Correction processing In order to achieve acceptable packet error rates, a concatenated outer and inner coding scheme is used on each uplink code block. The error correcting codes are both block codes. The outer code is a 12-symbol error correcting Reed-Solomon (RS) co
32、de, and the inner code is a one-bit error correcting binary code. The system does not use interleaving between the uplink outer code and the inner code. The FEC order of processing is encoding with the outer code followed by the inner code. 5.3.1 Uplink outer code The ST encodes two uplink packets a
33、nd the access control byte data using a Reed-Solomon systematic block code with 24-byte Reed-Solomon parity check field, as shown in figure 5.3.1.1. Byte 0Packet 0 Packet 1Access Control(MSB) (LSB)Byte 243108 Bytes 108 Bytes216 Bytes220 BytesRS Parity244 BytesTime4 Bytes 24 BytesFigure 5.3.1.1: Upli
34、nk outer code word The arrangement of each packet within a Reed-Solomon code word is by increasing byte number (0, 1, 2, ., 219), and within each byte, the order of the bits is MSB first as shown in figure 5.3.1.2. ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 9 Byte 0 Byte 1TimeByte 2 Byte 215.Figure 5.3
35、.1.2: Packets order of presentation to outer code encoder The uplink Reed-Solomon code is a systematic block code where each code word has 220 information symbols followed by 24-byte parity symbols. The resulting RS code is a (244,220) code. Each symbol is an element of a GF(28) field. Thus, each sy
36、mbol is made up of one byte or eight bits. The symbols for each code word are derived as described in the following operations: Let: M(x) = a polynomial of degree less than 220, where the coefficients are the symbols represented by each byte of the two user data packets and the access control field.
37、 The highest degree coefficient is taken from byte 0 of user data packet 0. The next coefficient is taken from byte 1, and so on, until the 0-degree coefficient is taken from byte 219. The value of the coefficients of the polynomial M(X) are represented by the respective value of each of the 220 byt
38、es, interpreted as elements of a GF(28) field. G(X) = generator polynomial for the code. The generator polynomial G(X) is defined to be a monic polynomial of degree 24 with coefficients in a GF(28) field as defined in table 5.3.1. Table 5.3.1: Generator function coefficients Index, decimal Coefficie
39、nt in GF(28) (8-tuple) 012345 67Exponent of coefficient term, decimal 0 1 0 0 0 0 0 1 1 45 1 0 0 1 1 0 1 1 0 250 2 1 1 1 0 0 0 1 1 118 3 0 0 0 0 1 0 1 1 108 4 1 0 1 1 0 1 0 1 252 5 1 1 1 1 0 0 1 0 136 6 1 0 1 1 0 1 0 0 18 7 1 0 1 0 0 0 0 1 128 8 1 1 0 1 1 1 1 1 234 9 1 0 1 1 1 1 1 0 243 10 0 0 1 1 0
40、 1 0 0 240 11 1 1 1 0 0 1 0 1 205 12 0 1 1 0 0 0 1 1 164 13 0 1 1 0 1 0 0 1 180 14 0 1 1 1 0 1 0 1 190 15 0 0 1 1 1 1 1 1 168 16 0 1 0 1 1 0 1 1 134 17 0 0 0 1 0 0 0 0 3 18 1 0 1 0 0 0 1 1 123 19 1 1 0 0 0 0 1 1 216 20 0 0 1 0 1 0 0 0 52 21 1 0 0 0 0 1 0 0 138 22 1 0 1 0 0 0 1 1 123 23 0 0 1 0 1 1 1
41、 1 230 24 1 0 0 0 0 0 0 0 0 NOTE: G(X) contains as roots nwhere is the primitive field element and n is an integer in the range from 0 to 24. ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 10P(X) = a polynomial of degree less than or equal to 23, where the coefficients are the parity symbols. The order of
42、transmission for the parity symbols is as follows: the coefficient for the term of degree 23 of P(X) is transmitted first, followed by the coefficient of the degree 22 term and so on, ending with the coefficient associated with the 0 degree term. The parity polynomial P(X) is formed by computing the
43、 remainder of the shifted information polynomial M(X) with respect to a generator polynomial G(X) of degree 24. All operations are performed using the arithmetic of GF(28). The version of GF(28) used has as a primitive element a root of the (binary) polynomial 1)(2348+= XXXXXf , or in octal 435, whe
44、re the high-order coefficient is to the left. C(X) = a polynomial of degree less than 244, where the coefficients are the transmitted symbols for the code word. The order of transmission for the code word symbols (polynomial coefficients) is by decreasing exponent value. () () ()XPXXMXC +=24where: (
45、) ()()() ()()82348241242in 01 ofroot a Modulo GFXXXXXXGXGXXMXPii=+=That is, the outer code word is structured as a polynomial C(X) made up of a shifted (by 24 positions) information polynomial M(X) and a parity polynomial P(X), with all coefficients being treated as elements of GF(28). 5.3.2 Uplink
46、block interleaving There is no block interleaving requirement for the uplink. 5.3.3 Uplink inner code Following the outer code encoding, the inner code encoder takes each symbol of the Reed-Solomon outer code code-word as the information source i(X). The ST uses a shortened Hamming inner code consis
47、ting of a systematic (12,8) binary block code that expands each 8-bit RS symbol to a 12-bit inner code word. Each inner code word includes a 4-bit parity field appended to each symbol of the outer code words as depicted in figure 5.3.3. I7Inner CodeParityRS Symbol InformationTimeI6 I5 I4 I3 I2 I1 I0
48、 P3 P2 P1 P0Inner Code WordBit 11 Bit 10 Bit 9 Bit 8 Bit 7 Bit 6 Bit 5 Bit 4 Bit 3 Bit 2 Bit 1 Bit 0Figure 5.3.3: Uplink inner code word format ETSI ETSI TS 102 188-3 V1.1.2 (2004-07) 11The four parity bits of the inner code are formulated in accordance with the following equations: 75310076320176540276543213iiiiipiiiiipiiiiipiiiiiiip=In the equations above the sign is to be interpreted as addition modulo 2. As it appears in a TDMA burst, an uplink code block wi
