1、 TIA STANDARD Regenerative Satellite Mesh-A (RMS-A) Air Interface - Physical Layer Specification - Part 3: Channel Coding TIA-1040.1.03 April 2005 TELECOMMUNICATIONS INDUSTRY ASSOCIATION The Telecommunications Industry Association represents the communications sector of NOTICE TIA Engineering Standa
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16、S. TIA-1040.1.03 1Contents Intellectual Property Rights4 Foreword 4 1 Scope5 2 References5 3 Definitions and abbreviations 5 3.1 Definitions. 5 3.2 Abbreviations 5 4 General .6 5 Uplink.6 5.1 Uplink code block structure 6 5.2 Uplink data scrambling. 7 5.3 Uplink Forward Error Correction processing.
17、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 block structure. 11 6.2 Downlink data scrambling 12 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
18、Downlink inner code . 15 Annex A (informative): Bibliography.18 History19 TIA-1040.1.03 2 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
19、 ETSI members and non-members, and can be found in ETSI SR 000 314: “Intellectual Property Rights (IPRs); 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:
20、/webapp.etsi.org/IPR/home.asp). 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 ETSI SR 000 314 (or the updates on the ETSI Web server) which are, or may be, or may
21、become, essential to the present document. Foreword This Technical Specification (TS) has been produced 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 inte
22、rface; Physical layer specification, as identified below: Part 1: “General description“; Part 2: “Frame structure“; Part 3: “Channel coding“; Part 4: “Modulation“; Part 5: “Radio transmission and reception“; Part 6: “Radio link control“; Part 7: “Synchronization“. TIA-1040.1.03 31 Scope The present
23、document defines the channel coding structure used within the SES BSM Regenerative 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
24、Void. 3 Definitions and abbreviations 3.1 Definitions For the purposes of the 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 functio
25、ns and control of the address resolution and resource management functionality 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
26、. Satellite Terminal (ST): terminal installed in the user premises terrestrial 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 fo
27、llowing abbreviations apply: FEC Forward Error Correction IP Internet Protocol 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 Divis
28、ion Multiple Access TIA-1040.1.03 4 4 General The functions of the physical layer are different for the uplink and downlink. The major functions are illustrated in figure 4. UPLINK DOWNLINKPart 3: Channel coding Part 2: Frame structure Part 4: Modulation Part 5: Radio transmission and reception tnPa
29、rt 7: Synchronization Block interleavingInner coding (convolutional)Downlink burstbuildingDownlink modulation (QPSK)ST receiverScramblingAssemble packetsinto code blocksOuter coding (Reed-Solomon)No interleavingInner coding(hamming)Uplink burstbuildingUplink modulation(OQPSK)Part6:Radio linkcontrolS
30、cramblingTiming and frequency controlST transmitterAssemble packetsinto code blocksOuter 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
31、 clause 5 and the downlink 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 form
32、ed with a set of user data packets and an access control field that have been processed with FEC to achieve acceptable packet error rates. TIA-1040.1.03 5Uplink 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 pa
33、ckets 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 shor
34、tened 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 scrambled220 bytesOuter codeReed-Solomon(244,220)Inner code block (12,8) 244 bytes366 bytesper code blockFigure 5.1: Uplin
35、k 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 destination type su
36、b-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 Destination type
37、 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 figure 5.2, w
38、here 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). TIA-1040.1.03 6 1 2 3 4 15Input DataPN SequenceScrambled DataX14X0X1Figure 5.2: Uplink data scrambler 5.3 Uplink Forward Error Corre
39、ction 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) code, and the inner code is a one-bit
40、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 and the access control byte data usin
41、g 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: Uplink outer code word The arrangement o
42、f 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. TIA-1040.1.03 7Byte 0 Byte 1TimeByte 2 Byte 215.Figure 5.3.1.2: Packets order of presentation to outer code encoder The u
43、plink 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 symbol is made up of one byte or eight bits. The symbols for each
44、 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. The highest degree coefficient is taken from byte 0 of user da
45、ta 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 bytes, interpreted as elements of a GF(28) field. G(X) = generator
46、 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 Coefficient in GF(28) (8-tuple) 012345 67Exponent of coefficient term, d
47、ecimal 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 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
48、 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 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. TIA-1040.1.03 8 P(X) = a polynomial of degree less than or equal to 23, where the coefficients are the parity symbols. The order of transmiss
