1、 International Telecommunication Union ITU-T G.975.1TELECOMMUNICATION STANDARDIZATION SECTOR OF ITU Corrigendum 2(07/2013) SERIES G: TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS Digital sections and digital line system Optical fibre submarine cable systems Forward error correction fo
2、r high bit-rate DWDM submarine systems Corrigendum 2 Recommendation ITU-T G.975.1 (2004) Corrigendum 2 ITU-T G-SERIES RECOMMENDATIONS TRANSMISSION SYSTEMS AND MEDIA, DIGITAL SYSTEMS AND NETWORKS INTERNATIONAL TELEPHONE CONNECTIONS AND CIRCUITS G.100G.199 GENERAL CHARACTERISTICS COMMON TO ALL ANALOGU
3、E CARRIER-TRANSMISSION SYSTEMS G.200G.299 INDIVIDUAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON METALLIC LINES G.300G.399 GENERAL CHARACTERISTICS OF INTERNATIONAL CARRIER TELEPHONE SYSTEMS ON RADIO-RELAY OR SATELLITE LINKS AND INTERCONNECTION WITH METALLIC LINES G.400G.449 COORDIN
4、ATION OF RADIOTELEPHONY AND LINE TELEPHONY G.450G.499 TRANSMISSION MEDIA AND OPTICAL SYSTEMS CHARACTERISTICS G.600G.699 DIGITAL TERMINAL EQUIPMENTS G.700G.799 DIGITAL NETWORKS G.800G.899 DIGITAL SECTIONS AND DIGITAL LINE SYSTEM G.900G.999 General G.900G.909 Parameters for optical fibre cable systems
5、 G.910G.919 Digital sections at hierarchical bit rates based on a bit rate of 2048 kbit/s G.920G.929 Digital line transmission systems on cable at non-hierarchical bit rates G.930G.939 Digital line systems provided by FDM transmission bearers G.940G.949 Digital line systems G.950G.959 Digital sectio
6、n and digital transmission systems for customer access to ISDN G.960G.969 Optical fibre submarine cable systems G.970G.979Optical line systems for local and access networks G.980G.989 Access networks G.990G.999 MULTIMEDIA QUALITY OF SERVICE AND PERFORMANCE GENERIC AND USER-RELATED ASPECTS G.1000G.19
7、99 TRANSMISSION MEDIA CHARACTERISTICS G.6000G.6999 DATA OVER TRANSPORT GENERIC ASPECTS G.7000G.7999 PACKET OVER TRANSPORT ASPECTS G.8000G.8999 ACCESS NETWORKS G.9000G.9999 For further details, please refer to the list of ITU-T Recommendations. Rec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) i Recommendati
8、on ITU-T G.975.1 Forward error correction for high bit-rate DWDM submarine systems Corrigendum 2 Summary Corrigendum 2 to Recommendation ITU-T G.975.1 (2004) covers the following functionalities: Corrections to the minimal polynomials of clauses I.3.2.1 and I.3.2.2. Corrections to Figure I.9 BCH(386
9、0,3824) frame format in clause I.3.2.3. Corrections to Figure I.11 BCH(2040,1930) frame format in clause I.3.2.3. Editorial clarification of the BCH code length in clause I.4 History Edition Recommendation Approval Study Group 1.0 ITU-T G.975.1 2004-02-22 15 1.1 ITU-T G.975.1 (2004) Cor. 1 2006-02-1
10、7 15 1.2 ITU-T G.975.1 (2004) Cor. 2 2013-07-12 15 ii Rec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) FOREWORD The International Telecommunication Union (ITU) is the United Nations specialized agency in the field of telecommunications, information and communication technologies (ICTs). The ITU Telecommuni
11、cation Standardization Sector (ITU-T) is a permanent organ of ITU. ITU-T is responsible for studying technical, operating and tariff questions and issuing Recommendations on them with a view to standardizing telecommunications on a worldwide basis. The World Telecommunication Standardization Assembl
12、y (WTSA), which meets every four years, establishes the topics for study by the ITU-T study groups which, in turn, produce Recommendations on these topics. The approval of ITU-T Recommendations is covered by the procedure laid down in WTSA Resolution 1. In some areas of information technology which
13、fall within ITU-Ts purview, the necessary standards are prepared on a collaborative basis with ISO and IEC. NOTE In this Recommendation, the expression “Administration“ is used for conciseness to indicate both a telecommunication administration and a recognized operating agency. Compliance with this
14、 Recommendation is voluntary. However, the Recommendation may contain certain mandatory provisions (to ensure, e.g., interoperability or applicability) and compliance with the Recommendation is achieved when all of these mandatory provisions are met. The words “shall“ or some other obligatory langua
15、ge such as “must“ and the negative equivalents are used to express requirements. The use of such words does not suggest that compliance with the Recommendation is required of any party. INTELLECTUAL PROPERTY RIGHTS ITU draws attention to the possibility that the practice or implementation of this Re
16、commendation may involve the use of a claimed Intellectual Property Right. ITU takes no position concerning the evidence, validity or applicability of claimed Intellectual Property Rights, whether asserted by ITU members or others outside of the Recommendation development process. As of the date of
17、approval of this Recommendation, ITU had received notice of intellectual property, protected by patents, which may be required to implement this Recommendation. However, implementers are cautioned that this may not represent the latest information and are therefore strongly urged to consult the TSB
18、patent database at http:/www.itu.int/ITU-T/ipr/. ITU 2013 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without the prior written permission of ITU. Rec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) 1 Recommendation ITU-T G.975.1 Forward error correction for hi
19、gh bit-rate DWDM submarine systems Corrigendum 2 1) Clause I.3.2.1 Revise clause I.3.2.1, BCH(3860,3824) code, as follows: I.3.2.1 BCH(3860,3824) code The BCH(3860,3824) code is a binary code. The generator polynomial of the code is given by: )()()()(531xMxMxMxG = =121*)()(jjiixxM =1212*)()(jjiixxM
20、where Mi(x) are minimal polynomials and is a root of the binary primitive polynomial x12+ x11+ x8+ x6+ 1. The BCH(3860,3824) codeword consists of 3824 information bits and 36 parity bits. The BCH(3860,3824) can correct up to 3 bit errors in a single codeword. 2) Clause I.3.2.2 Revise clause I.3.2.2,
21、 BCH(2040,1930) code, as follows: I.3.2.2 BCH(2040,1930) code The BCH(2040,1930) code is a binary code. The generator polynomial of the code is given by: )()()()()()()()()()()(191715131197531xMxMxMxMxMxMxMxMxMxMxG = =111*)()(jjiixxM =1112*)()(jjiixxM where Mi(x) are minimal polynomials and is a root
22、 of the binary primitive polynomial x11+ x2+ 1. The BCH(2040,1930) codeword consists of 1930 information bits and 110 parity bits. The BCH(2040,1930) can correct up to 10 bit errors in a single codeword. 3) Clause I.3.2.3, Figure I.9 Revise the dummy data fields in Figure I.9 as follows: 2 Rec. ITU-
23、T G.975.1 (2004)/Cor.2 (07/2013) I.3.2.3 Frame structure Figure I.9 BCH(3860,3824) frame format 4) Clause I.3.2.3, Figure I.11 Add a note to Figure I.11 as shown below: 96 bits 1664 bitsRec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) 3 G.975.1(04)-Cor.1(13)_FI.11row 13row 11row 12row 7row 6row 5row 4row 3
24、row 2row 1row 16row 10row 8row 9row 15row 14LSBBCH(2040,1930)codeword #1MSBMSBLSB1 8*16 16*16 1920*16column 1 column 2 column 242 column 255column 2411928*16 1936*16 2040*16BCH(2040,1930)frame formatFrame length = 32640 bitsrow 127row 125row 126row 124row 122row 123row 121row 128BCH(2040,1930)codewo
25、rd #16Column1Column2Column241Column240Column255Column242# codeword numberRow length = 255 bitsInformation data of BCH(2040,1930)Payload dataInput and output order Parity data ofBCH(2040,1930)Parity data ofBCH(3860,3824)LSBBCH(2040,1930)codeword #2MSBcolumn 2408*16+1Parity data of BCH(3860,3824) Pari
26、ty data of BCH(2040,1930)NOTE The area from row 17 to 120 of Column 242 is used for parity data of both BCH(3860,3824) and BCH(2040,1930) in the following manner: row (1+8*n), row (2+8*n) n=214; Parity data of BCH(3860,3824) row (3+8*n) row (8+8*n) n=214; Parity data of BCH(2040,1930). Figure I.11 B
27、CH(2040,1930) frame format 4 Rec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) 5) Clause I.4 Revise clause I.4 “RS(1023,1007)/BCH(2047,1952)super FEC code“ as follows: I.4 RS(1023,1007)/BCH(20472040,1952) super FEC code I.4.1 Overview This Super FEC consists of two interleaved codes: RS(1023,1007) parent ou
28、ter code, m = 10, T = 8. BCH(2047,1952) parent inner code, m = 11, T = 8 shortened to BCH(2040,1952). These two interleaved codes are targeted at providing additional coding gain on the standard G.709/Y.1331 ODU payload while maintaining the exact data rates at the G.709/Y.1331 OTU, i.e., 7% overhea
29、d. I.4.2 Super FEC algorithm I.4.2.1 Code interleaving The ODU payload consists of 16 239 4 8 bits = 122368 bits in total. These 122368 bits are divided into 16 groups and are then encoded with 15 RS(781,765) and one RS(778,762) code, both of which are shortened codes of the parent code listed above
30、. Note that the parent code above operates on an m = 10 Galois Field, so data are grouped into dectets and are operated on accordingly. If we number the ODU payload bits as odu0, odu1 up to odu122367, then the interleaving can be clearly explained. Keep in mind that odu0 is the first transmitted bit
31、, followed by odu1 and so on up to odu122367, i.e., in G.709/Y.1331 terms, odu0, odu1, odu2, odu3, odu4, odu5, odu6, odu7 = 0xf6, the first OA1 byte in the G.709/Y.1331 frame. Using this convention, we will now pack the odu bits into the payload portion of the RS codes. This first RS code RS0 is an
32、RS(781,765) over m = 10. Thus we need to pack 765 10 bits into the first 765 dectets of this code. Thus bits odu0.odu9 form the first dectet of the first RS code. Bits odu10.odu19 form the second dectet of RS0. The bits are repeatedly packed into 765 dectets of RS0 for a total of 7650 bits, i.e., od
33、u0.odu7649. At this point, the data is then RS encoded over m = 10 and T = 8, and 2T parity symbols are added to the code. Thus, the next 16 10 bits consist of RS parity. We will now consider the OTU output data. This consists of 16 255 4 8 bits or 130560 bits. We will number these bits otu0.otu1305
34、59. The first RS code is now mapped to the output otu, i.e., odu0.odu7649 otu0.otu7649. The next 160 bits of RS parity are now mapped to the otu, i.e., rsparity0.rsparity159 otu7650.otu7809. Having completed the first RS code, the next 7650 bits of odu are mapped to the otu, i.e., odu7650.odu15299 o
35、tu7810.otu15459. These 765 dectets are RS encoded, and the 160 bits of RS parity are inserted into the outgoing otu, i.e., rsparity0.rsparity159 otu15460.otu15619. This process is repeated for all 15 RS codes in the same manner. For the 16th and final code, there are 122368 15 765 10 = 7618 bits of
36、remaining odu. These bits are packed into 762 dectets. The final 2 bits, which are missing are 0 filled and packed into the last dectet. These 762 dectets are RS encoded with an RS(778,762) code. Again 160 bits of parity are added to the outgoing otu. Thus odu114749114750.odu122367 otu117149117150.o
37、tu124767. Note that the last 2 bits are 0 filled for the purpose of RS encoding; however, they are not actually transmitted into the outgoing otu. The 160 parity bits are added as follows: rsparity0.rsparity159 otu124768.otu124927. Rec. ITU-T G.975.1 (2004)/Cor.2 (07/2013) 5 Having completed the RS
38、outer code, the BCH inner code is now added to the otu. The 124928 otu bits are then mapped into 64 identical BCH codes of BCH(20472040,1952) with m = 11 and T = 8, the parent code is shown above. This requires the 124928 bits to be grouped into 64 partitions of 1952 bits. The BCH mapping is as foll
39、ows: otu0 is used as the first bit for BCH0. otu1 is used as the first bit for BCH1 repeatedly until otu63 is used as the first bit for BCH63. Then otu64 is used as the second bit for BCH0. otu65 is used as the second bit for BCH1. This process is repeated until all 124928 otu bits are consumed by t
40、he 64 BCH codes. For each of the 64 BCH codes, the 1952 payload bits are encoded and 88 parity bits are added to the output. The 88 bits result from the product of T = 8 and m = 11 for the BCH codes. The BCH parity is added to the output otu as follows: BCH0 bchparity0 otu124928, BCH1 bchparity0 otu
41、124929 repeatedly until BCH63 bchparity0 otu124992124991. Then the next bit of each BCH code is added to the output otu, i.e., BCH0 bchparity1 otu124993124992. This is repeated until all 64 BCH codes have exhausted their 88 parity bits. i.e., BCH63 bchparity87 otu130559 the last bit of the output ot
42、u frame. I.4.4 Redundancy ratio The redundancy ratio of the Interleaved RS(1023,1007)/BCH(20472040,1952) Code is 7%, the same as the legacy RS FEC as defined in ITU-T Rec. G.975. Printed in Switzerland Geneva, 2013 SERIES OF ITU-T RECOMMENDATIONS Series A Organization of the work of ITU-T Series D G
43、eneral tariff principles Series E Overall network operation, telephone service, service operation and human factors Series F Non-telephone telecommunication services Series G Transmission systems and media, digital systems and networks Series H Audiovisual and multimedia systems Series I Integrated
44、services digital network Series J Cable networks and transmission of television, sound programme and other multimedia signals Series K Protection against interference Series L Construction, installation and protection of cables and other elements of outside plant Series M Telecommunication managemen
45、t, including TMN and network maintenance Series N Maintenance: international sound programme and television transmission circuits Series O Specifications of measuring equipment Series P Terminals and subjective and objective assessment methods Series Q Switching and signalling Series R Telegraph tra
46、nsmission Series S Telegraph services terminal equipment Series T Terminals for telematic services Series U Telegraph switching Series V Data communication over the telephone network Series X Data networks, open system communications and security Series Y Global information infrastructure, Internet protocol aspects and next-generation networks Series Z Languages and general software aspects for telecommunication systems
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