Apparatus for decoding convolutional codes and associated method

• US 20070201584A1
• Filed: 02/08/2006
• Published: 08/30/2007
• Est. Priority Date: 02/08/2006
• Status: Active Grant

• Current Assignee: Harris Global Communications, Inc. (L3Harris Technologies, Inc.)
• Original Assignee: Harris Corporation (L3Harris Technologies, Inc.)
• Inventors: Furman, William, Nieto, John
• Granted Patent: US 7,693,239 B2
• Time in Patent Office: Days
• US Class Current: 375/341
• CPC Class Codes: H04L 1/0036 arrangements specific to the receiver
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0059 Convolutional codes

Abstract

A decoding device may include a sequential convolutional code decoder, and a parallel convolutional code decoder. The decoding device may further include a controller for selectively processing a convolutionally encoded input signal via at least one of the sequential convolutional code decoder and the parallel convolutional code decoder. The selection of decoder may be based upon a signal-to-noise ratio or the passage of time, for example.

Claims

1. A decoding device comprising:

a sequential convolutional code decoder;

a parallel convolutional code decoder; and

a controller for selectively processing a convolutionally encoded input signal via at least one of said sequential convolutional code decoder and said parallel convolutional code decoder.

2. The decoding device according to claim 1 wherein said controller determines a signal-to-noise ratio (SNR) of the convolutionally encoded input signal, processes the convolutionally encoded input signal via said sequential convolutional code decoder if the SNR is above a SNR threshold, and processes the convolutionally encoded input signal via said parallel convolutional code decoder if the SNR is below the SNR threshold.

3. The decoding device according to claim 2 wherein said controller determines the SNR threshold based upon at least one of a modulation type and code rate of the convolutionally encoded input signal.

4. The decoding device according to claim 1 wherein said controller initially processes the convolutionally encoded input signal via said sequential convolutional code decoder, and after a threshold time thereafter processes the convolutionally encoded input signal via said parallel convolutional code decoder.

5. The decoding device according to claim 4 wherein said parallel convolutional code decoder uses partially decoded data from said sequential convolutional code decoder.

6. The decoding device according to claim 4 wherein said parallel convolutional code decoder does not use partially decoded data from said sequential convolutional code decoder.

7. The decoding device according to claim 1 wherein said sequential convolutional code decoder comprises a Fano decoder.

8. The decoding device according to claim 1 wherein said parallel convolutional code decoder comprises a Viterbi decoder.

9. The decoding device according to claim 1 wherein said sequential convolutional code decoder has a first constraint length, and said parallel convolutional code decoder has a second constraint length equal to said first constraint length.

10. The decoding device according to claim 9 wherein each of the first and second constraint lengths is less than about 10.

11. An electronic device comprising:

a wireless receiver for receiving a convolutionally encoded input signal;

a sequential convolutional code decoder;

a parallel convolutional code decoder; and

a controller determining a signal-to-noise ratio (SNR) of the convolutionally encoded input signal, processing the convolutionally encoded input signal via said sequential convolutional code decoder if the SNR is above a threshold, and processing the convolutionally encoded input signal via said parallel convolutional code decoder if the SNR is below the SNR threshold.

12. The electronic device according to claim 11 wherein said controller determines the SNR threshold based upon at least one of a modulation type and code rate of the convolutionally encoded input signal.

13. The electronic device according to claim 11 wherein said sequential convolutional code decoder comprises a Fano decoder.

14. The electronic device according to claim 11 wherein said parallel convolutional code decoder comprises a Viterbi decoder.

15. The electronic device according to claim 11 wherein said sequential convolutional code decoder has a first constraint length, and said parallel convolutional code decoder has a second constraint length equal to said first constraint length.

16. The electronic device according to claim 15 wherein each of the first and second constraint lengths is less than about 10.

17. An electronic device comprising:

a wireless receiver for receiving a convolutionally encoded input signal;

a sequential convolutional code decoder;

a parallel convolutional code decoder; and

a controller initially processing the convolutionally encoded input signal via said sequential convolutional code decoder, and after a threshold time thereafter processing the convolutionally encoded input signal via said parallel convolutional code decoder.

18. The electronic device according to claim 17 wherein said parallel convolutional code decoder uses partially decoded data from said sequential convolutional code decoder.

19. The electronic device according to claim 17 wherein said parallel convolutional code decoder does not use partially decoded data from said sequential convolutional code decoder.

20. The electronic device according to claim 17 wherein said sequential convolutional code decoder comprises a Fano decoder.

21. The electronic device according to claim 17 wherein said parallel convolutional code decoder comprises a Viterbi decoder.

22. The electronic device according to claim 17 wherein said sequential convolutional code decoder has a first constraint length, and said parallel convolutional code decoder has a second constraint length equal to said first constraint length.

23. The electronic device according to claim 22 wherein each of the first and second constraint lengths is less than about 10.

24. A method of decoding a convolutionally encoded input signal using a decoding device comprising a sequential convolutional code decoder, a parallel convolutional code decoder, and a controller connected to the sequential convolutional code decoder and the parallel convolutional code decoder, the method comprising:

operating the controller to selectively process the convolutionally encoded input signal via at least one of the sequential convolutional code decoder and the parallel convolutional code decoder.

25. The method according to claim 24 wherein the controller determines a signal-to-noise ratio (SNR) of the convolutionally encoded input signal, processes the convolutionally encoded input signal via the sequential convolutional code decoder if the SNR is above a threshold, and processes the convolutionally encoded input signal via the parallel convolutional code decoder if the SNR is below the SNR threshold.

26. The method according to claim 24 wherein the controller initially processes the convolutionally encoded input signal via the sequential convolutional code decoder, and after a threshold time thereafter processes the convolutionally encoded input signal via the parallel convolutional code decoder.

27. The method according to claim 24 wherein the sequential convolutional code decoder comprises a Fano decoder;

and wherein the parallel convolutional code decoder comprises a Viterbi decoder.

28. The method according to claim 24 wherein the sequential convolutional code decoder has a first constraint length, and the parallel convolutional code decoder has a second constraint length equal to the first constraint length;

and wherein each of the first and second constraint lengths is less than about 10.