Computationally efficient convolutional coding with rate-matching

• US 9,467,176 B2
• Filed: 11/13/2015
• Issued: 10/11/2016
• Est. Priority Date: 06/08/2007
• Status: Active Grant

• Current Assignee: Telefonaktiebolaget LM Ericsson
• Original Assignee: Telefonaktiebolaget LM Ericsson
• Inventors: Cheng, Jung-Fu
• Primary Examiner(s): Chase, Shelly A
• Application Number:
  US14/940,842
• Publication Number:
  US 20160072526A1
• Time in Patent Office: 333 Days
• US Class Current: 1/1
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• CPC Class Codes: H03M 13/235 Encoding of convolutional codes, e.g. methods or arrangements for parallel or block-wise encoding
• CPC Class Codes: H03M 13/27 using interleaving techniques
• CPC Class Codes: H03M 13/2732 Convolutional interleaver; Interleavers using shift-registers or delay lines like, e.g. Ramsey type interleaver
• CPC Class Codes: H03M 13/2792 Interleaver wherein interleaving is performed jointly with another technique such as puncturing, multiplexing or routing
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• CPC Class Codes: H03M 13/6356 by repetition or insertion of dummy data, i.e. rate reduction
• CPC Class Codes: H03M 13/6362 by puncturing
• CPC Class Codes: H04L 1/0059 Convolutional codes
• CPC Class Codes: H04L 1/0069 Puncturing patterns
• CPC Class Codes: H04L 1/0071 Use of interleaving interleaving per se H03M13/27

Abstract

An error coding circuit comprises a non-systematic convolutional encoder for coding an input bit stream to produce two or more groups of parity bits, an interleaver circuit for interleaving parity bits within each group of parity bits, and a rate-matching circuit for outputting a selected number of the interleaved parity bits ordered by group to obtain a desired code rate.

Claims

1. A communication terminal for a mobile communications system, comprising,

an error coding circuit, the error coding circuit further comprised of:

a non-systematic convolutional encoder for coding an input bit stream to produce two or more groups of parity bits;

an interleaver circuit for interleaving parity bits within each group of parity bits, wherein the interleaver circuit is configured to order parity bits such that odd parity bits precede even parity bits within each group of parity bits; and

a rate-matching circuit for outputting a selected number of said interleaved parity bits ordered by group to obtain a desired code rate.

2. The communication terminal of claim 1, wherein said interleaver circuit implements a reverse bit-reversal order interleaver for column permutation.

3. The communication terminal of claim 1, wherein said interleaver circuit implements a cyclically-shifted bit-reversal order interleaver for column permutation.

4. The communication terminal of claim 1, wherein said interleaver circuit implements a modulo-offset bit-reversal order interleaver for column permutation.

5. The communication terminal of claim 1, wherein the error coding circuit further comprises a channel interleaver following the rate-matching circuit.

6. A communication terminal for a mobile communications system, comprising,

an error coding circuit, the error coding circuit further comprised of:

a non-systematic convolutional encoder for coding an input bit stream to produce two or more groups of parity bits;

an interleaver circuit for interleaving parity bits within each group of parity bits; and

a rate-matching circuit for outputting a selected number of said interleaved parity bits ordered by group to obtain a desired code rate, wherein said rate-matching circuit is configured to puncture parity bits, when the encoder produces more bits than needed to match a data communication channel, by puncturing up to all of the parity bits in one of the groups of parity bits before puncturing bits in any other group of parity bits.

7. The communication terminal of claim 6, wherein the rate-matching circuit is configured to repeat parity bits, when the encoder produces fewer bits than needed to match a data communication channel, by repeating up to all of the parity bits in one of the groups of parity bits before repeating bits in any other group of parity bits.

8. A method of a communication terminal for a mobile communications system, the method for error coding an input bit stream, said method comprising:

coding said input bit stream in a non-systematic convolutional encoder to produce two or more groups of parity bits;

interleaving parity bits within each group of parity bits, such that odd parity bits precede even parity bits within each group of parity bits; and

outputting a selected number of said interleaved parity bits ordered by group to obtain a desired code rate.

9. The method of claim 8, wherein said interleaving comprises a reverse bit-reversal order interleaving for column permutation.

10. The method of claim 8, wherein said interleaving comprises a cyclically-shifted bit-reversal order interleaving for column permutation.

11. The method of claim 8, wherein said interleaving comprises a modulo-offset bit-reversal order interleaving for column permutation.

12. A method of a communication terminal for a mobile communications system, the method for error coding an input bit stream, said method comprising:

coding said input bit stream in a non-systematic convolutional encoder to produce two or more groups of parity bits;

interleaving parity bits within each group of parity bits; and

outputting a selected number of said interleaved parity bits ordered by group to obtain a desired code rate, wherein said outputting comprises puncturing parity bits, when said coding produces more bits than needed to match a data communication channel, by puncturing up to all of the parity bits in one of the groups of parity bits before puncturing bits in any other group of parity bits.

13. The method of claim 12, wherein said outputting comprises repeating parity bits, when said coding produces fewer bits than needed to match a data communication channel, by repeating up to all of the parity bits in one of the groups of parity bits before repeating bits in any other group of parity bits.

14. A communication terminal for a mobile communications system, comprising,

an error coding circuit, the error coding circuit further comprised of:

a non-systematic convolutional encoder for coding an input bit stream to produce three groups of parity bits, wherein said encoder implements a rate ⅓

tail-biting convolutional code belonging to the class of maximum free distance codes with optimal distance spectra, such that a rate ½

code belonging to the class of maximum free distance codes with optimal distance spectra can be obtained by puncturing one of the groups of parity bits;

an interleaver circuit for interleaving parity bits within each group of parity bits; and

a rate-matching circuit for outputting a selected number of said interleaved parity bits ordered by group to obtain a desired code rate.

15. The communication terminal of claim 14, wherein said encoder implements a rate ⅓

tail-biting convolutional code with a constraint length k=7 and a generator polynomial [133, 171, 165]o.

16. The communication terminal of claim 14, wherein said encoder implements a rate ½

tail-biting convolutional code with a constraint length k=7 and a generator polynomial [133, 171]o.