Parallel concatenated code with soft-in soft-out interactive turbo decoder

• US 7,460,608 B2
• Filed: 07/22/2004
• Issued: 12/02/2008
• Est. Priority Date: 09/12/2000
• Status: Expired due to Fees

• Current Assignee: Broadcom Corporation (Broadcom, Inc.)
• Original Assignee: Broadcom Corporation (Broadcom, Inc.)
• Inventors: Shen, Ba-Zhong, Jones, Christopher R., Tran, Hau Thien, Cameron, Kelly B.
• Primary Examiner(s): WANG, TED M
• Application Number:
  US10/897,201
• Publication Number:
  US 20050022090A1
• Time in Patent Office: 1,594 Days
• Field of Search: 375/265, 375/262, 375/295, 375/341, 714/746, 714/701, 714/755
• US Class Current: 375/265
• 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 13/25 Error detection or forward error correction by signal space coding, i.e. adding redundancy in the signal constellation, e.g. Trellis Coded Modulation [TCM] modulation codes H03M13/31
• CPC Class Codes: H03M 13/258 with turbo codes, e.g. Turbo Trellis Coded Modulation [TTCM]
• CPC Class Codes: H03M 13/27 using interleaving techniques
• CPC Class Codes: H03M 13/2757 Interleaver with an interleaving rule not provided for in the subgroups H03M13/2703 - H03M13/2753
• 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 13/2966 Turbo codes concatenated with another code, e.g. an outer block code
• CPC Class Codes: H03M 13/2978 Particular arrangement of the component decoders
• CPC Class Codes: H03M 13/3905 Maximum a posteriori probability [MAP] decoding or approximations thereof based on trellis or lattice decoding, e.g. forward-backward algorithm, log-MAP decoding, max-log-MAP decoding
• CPC Class Codes: H03M 13/3922 Add-Compare-Select [ACS] operation in forward or backward recursions
• CPC Class Codes: H03M 13/3927 Log-Likelihood Ratio [LLR] computation by combination of forward and backward metrics into LLRs
• CPC Class Codes: H03M 13/3972 using sliding window techniques or parallel windows
• CPC Class Codes: H03M 13/3988 for rate k/n convolutional codes, with k>1, obtained by convolutional encoders with k inputs and n outputs
• CPC Class Codes: H03M 13/4107 implementing add, compare, select [ACS] operations
• CPC Class Codes: H03M 13/6505 Memory efficient implementations
• CPC Class Codes: H03M 13/6561 Parallelized implementations
• CPC Class Codes: H04L 1/0041 Arrangements at the transmitter end
• CPC Class Codes: H04L 1/005 Iterative decoding, including iteration between signal detection and decoding operation
• CPC Class Codes: H04L 1/006 Trellis-coded modulation
• CPC Class Codes: H04L 1/0065 : Serial concatenated codes
• CPC Class Codes: H04L 1/0066 : Parallel concatenated codes
• CPC Class Codes: H04L 1/0068 : by puncturing
• CPC Class Codes: H04L 1/0071 : Use of interleaving interleaving per se H03M13/27

Abstract

A method for parallel concatenated (Turbo) encoding and decoding. Turbo encoders receive a sequence of input data tuples and encode them. The input sequence may correspond to a sequence of an original data source, or to an already coded data sequence such as provided by a Reed-Solomon encoder. A turbo encoder generally comprises two or more encoders separated by one or more interleavers. The input data tuples may be interleaved using a modulo scheme in which the interleaving is according to some method (such as block or random interleaving) with the added stipulation that the input tuples may be interleaved only to interleaved positions having the same modulo-N (where N is an integer) as they have in the input data sequence. If all the input tuples are encoded by all encoders then output tuples can be chosen sequentially from the encoders and no tuples will be missed. If the input tuples comprise multiple bits, the bits may be interleaved independently to interleaved positions having the same modulo-N and the same bit position. This may improve the robustness of the code. A first encoder may have no interleaver or all encoders may have interleavers, whether the input tuple bits are interleaved independently or not. Modulo type interleaving also allows decoding in parallel.

Claims

1. A method of encoding data tuples, the method comprising:

encoding the data tuples with a Reed-Solomon code;

turbo trellis encoding the data tuples that have been encoded with the Reed-Solomon code; and

mapping a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein the mapping comprises;

mapping the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, to a first constellation whose constellation points have a first corresponding mapping; and

mapping the bit of the turbo trellis encoded data tuple to a second constellation whose constellation points have a second corresponding mapping.

2. The method of claim 1, wherein turbo trellis encoding the tuples comprises turbo trellis modulo-N encoding the tuples.

3. The method of claim 2, wherein turbo trellis encoding the tuples comprises ST (Separate Tuple) interleaving the tuples.

4. The method of claim 2, wherein turbo trellis encoding the tuples comprises ST (Separate Tuple) interleaving the tuples prior to providing them to any constituent encoder.

5. The method of claim 1, wherein:

the turbo trellis encoding performs systematic encoding.

6. The method of claim 1, further comprising:

before mapping the turbo trellis encoded data tuple, puncturing a bit from the turbo trellis encoded data tuple.

7. An encoder that encodes data tuples, the encoder comprising:

a Reed-Solomon encoder that encodes the data tuples;

a turbo trellis encoder that performs turbo trellis encoding of the data tuples that have been encoded with the Reed-Solomon encoder; and

a mapper implemented to map a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein;

the mapper is implemented to map the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, to a first constellation whose constellation points have a first corresponding mapping; and

the mapper is implemented to map the bit of the turbo trellis encoded data tuple to a second constellation whose constellation points have a second corresponding mapping.

8. The encoder of claim 7, wherein the turbo trellis encoder comprises a turbo trellis modulo-N encoder.

9. The encoder of claim 8, wherein turbo trellis encoder comprises an ST (Separate Tuple) interleaver.

10. The encoder of claim 8, wherein turbo trellis encoder comprises ST (Separate Tuple) interleavers that interleave data tuples prior to providing them to any constituent encoder.

11. The encoder of claim 7, wherein:

the turbo trellis encoder performs systematic encoding.

12. The encoder of claim 7, further comprising:

a puncturing module implemented to puncture a bit from the turbo trellis encoded data tuple.

13. A method of encoding data tuples, the method comprising:

encoding the data tuples with a Reed-Solomon code;

turbo trellis encoding the data tuples that have been encoded with the Reed-Solomon code; and

mapping a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein;

the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, and the bit of the turbo trellis encoded data tuple are included within a single symbol.

14. The method of claim 13, wherein:

the turbo trellis encoding performs systematic encoding.

15. A method of encoding data tuples, the method comprising:

encoding the data tuples with a Reed-Solomon code;

turbo trellis encoding the data tuples that have been encoded with the Reed-Solomon code; and

mapping a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein;

the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoding, is included within a first symbol;

the bit of the turbo trellis encoded data tuple is included within a second symbol; and

each of the first symbol and the second symbol undergo mapping.

16. The method of claim 15, wherein:

the turbo trellis encoding performs systematic encoding.

17. An encoder that encodes data tuples, the encoder comprising:

a Reed-Solomon encoder that encodes the data tuples;

a turbo trellis encoder that performs turbo trellis encoding of the data tuples that have been encoded with the Reed-Solomon encoder; and

a mapper implemented to map a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein;

the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, and the bit of the turbo trellis encoded data tuple are included within a single symbol.

18. The encoder of claim 17, wherein:

the turbo trellis encoder performs systematic encoding.

19. An encoder that encodes data tuples, the encoder comprising:

a Reed-Solomon encoder that encodes the data tuples;

a turbo trellis encoder that performs turbo trellis encoding of the data tuples that have been encoded with the Reed-Solomon encoder; and

a mapper implemented to map a bit of a Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, and a bit of a turbo trellis encoded data tuple to at least one constellation whose constellation points have at least one corresponding mapping; and

wherein;

the bit of the Reed-Solomon encoded data tuple, that has bypassed the turbo trellis encoder, is included within a first symbol;

the bit of the turbo trellis encoded data tuple is included within a second symbol; and

each of the first symbol and the second symbol are mapped in the mapper.

20. The encoder of claim 19, wherein:

the turbo trellis encoder performs systematic encoding.