Concatenated forward error correction decoder

• US 20020166091A1
• Filed: 03/25/2002
• Published: 11/07/2002
• Est. Priority Date: 06/05/2000
• Status: Active Grant

• Current Assignee: Tyco Electronics Subsea Communications LLC (TE Connectivity Limited)
• Original Assignee: Tyco Telecommunications Us Incorporated (Johnson Controls International plc)
• Inventors: Kerfoot, Franklin W. III, Pedersen, Bo, Kidorf, Howard D., Ramanujam, Nandakumar
• Granted Patent: US 7,032,154 B2
• Time in Patent Office: Days
• US Class Current: 714/752
• CPC Class Codes: H03M 13/151 using error location or error correction polynomials
• CPC Class Codes: H03M 13/1515 Reed-Solomon codes
• CPC Class Codes: H03M 13/152 Bose-Chaudhuri-Hocquenghem [BCH] codes
• CPC Class Codes: H03M 13/29 combining two or more codes or code structures, e.g. product codes, generalised product codes, concatenated codes, inner and outer codes
• CPC Class Codes: H03M 13/2909 Product codes
• CPC Class Codes: H03M 13/2927 Decoding strategies
• CPC Class Codes: H03M 13/2948 Iterative decoding H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0065 Serial concatenated codes
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27
• CPC Class Codes: H04L 2001/0098 Unequal error protection

Abstract

A method and apparatus for performing error correction is described. A stream of data is encoded using concatenated error correcting codes. The encoded data is communicated over a transmission system. The encoded data is decoded using the codes and three levels of decoding.

Claims

1. A method of performing error correction comprising:

encoding a stream of data using concatenated reed-solomon and turbo-code error correcting codes;

communicating said encoded data over a transmission system; and

decoding said encoded data using said reed-solomon and turbo-code error correcting codes and three levels of decoding.

2. The method of claim 1, wherein said transmission system is a long-haul transmission system.

3. The method of claim 2, wherein said long-haul transmission system communicates said encoded data at least 600 kilometers.

4. The method of claim 1, wherein said encoding comprises:

packing said stream of data into a first frame of first blocks;

generating said reed-solomon error correcting code for each of said first blocks;

appending check symbols of said reed-solomon code to said first blocks to create a second frame of second blocks;

packing said second frame of said blocks into a third frame of third blocks; and

generating said turbo-code error correcting code using said third blocks to create a fourth frame.

5. The method of claim 4, wherein said packing said frame of second blocks into a third frame of third blocks comprises interleaving said second blocks into said third blocks.

6. The method of claim 5, wherein said decoding comprises:

recovering check bits of said turbo-code error correcting code and said third blocks from said fourth frame;

correcting errors for said third blocks using said turbo-code error correcting code check bits;

unpacking said second blocks from said third blocks;

recovering said reed-solomon error correcting code check symbols and said first blocks from said second blocks;

correcting errors for said first blocks using said reed-solomon error correcting code check symbols;

appending said reed-solomon error correcting code check symbols to said corrected first blocks to create a fifth frame of fifth blocks;

packing said fifth frame of fifth blocks into a sixth frame of sixth blocks;

correcting errors for said sixth blocks using said turbo-code error correcting code;

unpacking said fifth blocks from said corrected sixth blocks; and

removing said reed-solomon error correcting code check symbols from said fifth blocks.

7. The method of claim 6, wherein said unpacking said second blocks from said third blocks comprises deinterleaving said third blocks into said second blocks.

8. The method of claim 6, wherein said packing said fifth frame comprises interleaving said fifth blocks into said sixth blocks.

9. The method of claim 6, wherein said unpacking said fifth blocks comprises deinterleaving said corrected sixth blocks into said fifth blocks.

10. The method of claim 1, wherein said reed-solomon error correcting code is an x/207 reed-solomon error correcting code.

11. The method of claim 1, wherein said reed-solomon error correcting code is (255/247) code and said turbo-code is a (64,57) TPC code.

12. The method of claim 1, wherein said turbo-code is one of a group comprising turbo convolutional codes and turbo product codes.

14. The machine-readable medium of claim 13, wherein said transmission system is a long-haul transmission system.

15. The machine-readable medium of claim 14, wherein said long-haul transmission system communicates said encoded data at least 600 kilometers.

16. The machine-readable medium of claim 13, wherein said encoding comprises:

packing said stream of data into a first frame of first blocks;

generating said reed-solomon error correcting code for each of said first blocks;

appending check symbols of said reed-solomon code to said first blocks to create a second frame of second blocks;

packing said second frame of second blocks into a third frame of third blocks; and

generating said turbo-code error correcting code using said third blocks to create a fourth frame.

17. The machine-readable medium of claim 16, wherein said packing said second frame of second blocks into a third frame of third blocks comprises interleaving said second blocks into said third blocks.

18. The machine-readable medium of claim 17, wherein said decoding comprises:

recovering said turbo-code error correcting code and said third blocks from said fourth frame;

correcting errors for said third blocks using said turbo-code error correcting code;

unpacking said second blocks from said third blocks;

recovering said reed-solomon error correcting code check symbols and said first blocks from said second blocks;

correcting errors for said first blocks using said reed-solomon error correcting code check symbols;

appending said reed-solomon error correcting code check symbols to said corrected first blocks to create a fifth frame of fifth blocks;

packing said fifth frame of fifth blocks into a sixth frame of sixth blocks;

correcting errors for said sixth blocks using said turbo-code error correcting code;

unpacking said fifth blocks from said corrected sixth blocks; and

removing said reed-solomon error correcting code check symbols from said fifth blocks.

19. The machine-readable medium of claim 18, wherein said unpacking said second blocks from said third blocks comprises deinterleaving said third blocks into said second blocks.

20. The machine-readable medium of claim 18, wherein said packing said fifth frame comprises interleaving said fifth blocks into said sixth blocks.

21. The machine-readable medium of claim 18, wherein said unpacking said fifth blocks comprises deinterleaving said corrected sixth blocks into said fifth blocks.

22. The machine-readable medium of claim 13, wherein said reed-solomon error correcting code is an x/207 reed-solomon error correcting code.

23. The machine-readable medium of claim 13, wherein said reed-solomon error correcting code is (255/247) code and said turbo-code is a (64,57) TPC code.

24. The machine-readable medium of claim 13, wherein said turbo code is one of a group comprising turbo convolutional codes and turbo product codes.

26. The apparatus of claim 25, wherein said forward error correction decoder comprises:

a first decoder to perform first level decoding on said encoded stream of data;

a first deinterleaver to deinterleave said encoded stream of data;

a second decoder to perform second level decoding on said deinterleaved encoded stream of data;

an interleaver to interleave said second level decoded stream of data;

a third decoder to perform third level decoding on said interleaved stream of data; and

a second deinterleaver to deinterleave said third level decoded stream of data.

27. The apparatus of claim 26, wherein said third level decoding of said forward error correction decoder provides a coding gain of approximately 0.45 decibels.

13. A machine-readable medium whose contents cause a computer system to perform forward error correcting, comprising:

encoding a stream of data using concatenated reed-solomon and turbo-code error correcting codes;

communicating said encoded data over a transmission system; and

decoding said encoded data using said reed-solomon and turbo-code error correcting codes and three levels of decoding.

25. An apparatus to perform forward error correction, comprising:

a transceiver to receive an encoded stream of data from a transmission system, wherein said encoded stream of data was encoded using concatenated reed-solomon and turbo-code error correcting codes; and

A forward error correction decoder to decode said received stream of data using said concatenated reed-solomon and turbo-code error correcting codes and three levels of decoding.

28. A system to perform forward error correction, comprising;

a forward error correction encoder to encode a data stream using concatenated reed-solomon and turbo-code error correcting codes;

a communications network to communicate said encoded data stream; and

a forward error correction decoder to decode said encoded data stream using said concatenated reed-solomon and turbo-code error correcting codes and three levels of decoding.