DECODING METHOD FOR CONVOLUTIONALLY CODED SIGNAL

• US 20160204803A1
• Filed: 01/11/2016
• Published: 07/14/2016
• Est. Priority Date: 01/12/2015
• Status: Active Grant

• Current Assignee: Xueshan Technologies Inc. (Wi-LAN Inc.)
• Original Assignee: MStar Semiconductor Incorporated (MediaTek, Inc.)
• Inventors: Ku, Yu-Hsien
• Granted Patent: US 10,116,337 B2
• Time in Patent Office: Days
• US Class Current: 1/1
• CPC Class Codes: H03M 13/23 using convolutional codes, e.g. unit memory codes
• CPC Class Codes: H03M 13/256 with trellis coding, e.g. with convolutional codes and TCM
• CPC Class Codes: H03M 13/258 with turbo codes, e.g. Turbo Trellis Coded Modulation [TTCM]
• CPC Class Codes: H03M 13/2957 Turbo codes and decoding
• 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 13/3938 Tail-biting H03M13/2996 takes precedence
• CPC Class Codes: H03M 13/3972 using sliding window techniques or parallel windows
• CPC Class Codes: H03M 13/413 tail biting Viterbi decoding

Abstract

A decoding method for a convolutionally coded signal is provided. The convolutionally coded signal includes a trellis. The decoding method includes determining a plurality of first sub-trellises from the trellis, decoding the first sub-trellises, determining a plurality of second sub-trellises from the trellis, boundaries of the second sub-trellises being different from boundaries of the first sub-trellises, and decoding the second sub-trellises.

Claims

1. A decoding method for a convolutionally coded signal, the convolutionally coded signal comprising a trellis, the decoding method comprising:

determining a plurality of first sub-trellises from the trellis, and determining a predetermined step from each of the first sub-trellises;

decoding the first sub-trellises to generate a plurality of state metrics;

storing a plurality of state metrics prior and subsequent to the predetermined steps as a first record;

determining a plurality of second sub-trellises from the trellis; and

decoding the second sub-trellises by utilizing the first record as an initial condition of the second sub-trellises.

2. The decoding method according to claim 1, wherein the step of determining the second sub-trellises from the trellis is performed according the predetermined steps.

3. The decoding method according to claim 1, wherein the step of decoding the first sub-trellises to generate the state metrics comprises:

decoding the first sub-trellises by forward recursion to generate a plurality of forward state metrics; and

decoding the first sub-trellises by backward recursion to generate a plurality of backward state metrics;

wherein, each the state metrics prior and subsequent to the predetermined steps comprises one of the forward state metrics and one of the backward state metrics.

4. The decoding method according to claim 1, wherein each of the first sub-trellises has a first sub-trellis length, each of the second sub-trellises has a second sub-trellis length, and the first sub-trellis length is equal to the second sub-trellis length.

5. The decoding method according to claim 1, wherein the step of decoding the first sub-trellises is decoding the first sub-trellises in a parallel manner.

6. The decoding method according to claim 1, wherein the steps of decoding and first and second sub-trellises are based on a soft-in-soft-out (SISO) decoding method.

7. The decoding method according to claim 1, wherein the step decoding the first sub-trellises is a half-iteration of one iteration, and the step of decoding the second sub-trellises is a half-iteration of another iteration.

8. A decoding method for a convolutionally coded signal, the convolutionally coded signal comprising a trellis, the decoding method comprising:

determining a plurality of first sub-trellises from the trellis, the first sub-trellises forming the trellis;

decoding the first sub-trellises;

determining a plurality of second sub-trellises from the trellis, the second sub-trellises forming the trellis, boundaries of the second sub-trellises being different from boundaries of the first sub-trellises; and

decoding the second sub-trellises.

9. The decoding method according to claim 8, wherein the first sub-trellises are non-overlapping.

10. The decoding method according to claim 8, further comprising:

when decoding the first sub-trellises, generating a plurality of state metrics for the first sub-trellises; and

when decoding the second sub-trellises, utilizing the state metrics as initial conditions of the second sub-trellises.

11. The decoding method according to claim 8, wherein the step of

decoding the first sub-trellises comprises:

decoding one of the first sub-trellises by forward recursion to generate a forward state metric, the forward state metric corresponding to a first step of the trellis; and

decoding the one of the first sub-trellises by backward recursion to generate a backward state metric, the backward state metric corresponding to a second step of the trellis, the first and second steps being adjacent to each other, the second step being earlier than the first step; and

the step of decoding the second sub-trellises comprises;

utilizing the backward state metric as an initial condition for decoding one of the second sub-trellises; and

utilizing the forward state metric as an initial condition of another of the second sub-trellises, the another of the second sub-trellises following the one of the second sub-trellis.

12. The decoding method according to claim 8, wherein each of the first sub-trellises has a first sub-trellis length, each of the second sub-trellises has a second sub-trellis length, and the first sub-trellis length is equal to the second sub-trellis length.

13. The decoding method according to claim 8, wherein the step of decoding the first sub-trellises is decoding the first sub-trellises in a parallel manner.

14. The decoding method according to claim 8, wherein the first sub-trellises comprise a previous first sub-trellis and a next first sub-trellis, one of the second sub-trellises comprises a part of the previous first sub-trellis and a part of the next first sub-trellis, and the next first sub-trellis follows to the previous first sub-trellis.

15. The decoding method according to claim 8, further comprising:

providing a turbo decoder;

wherein, the turbo decoder decodes the trellis twice in one iteration loop, and the steps of decoding the first sub-trellises and the step of decoding the second sub-trellises are from different iteration loops.

16. The decoding method according to claim 8, wherein the step of decoding the first sub-trellises and the step of decoding the second sub-trellises calculate soft output for each step by utilizing a maximum a posteriori (MAP) algorithm, and the MAP algorithm is one of log-MAP, MAP, max-log-MAP and constant-log-MAP algorithms.