Speech data receiver with detection of channel-coding rate

• US 20060281485A1
• Filed: 01/05/2004
• Published: 12/14/2006
• Est. Priority Date: 01/21/2003
• Status: Active Grant

• Current Assignee: Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Original Assignee: Sony Ericsson Mobile Communications USA Incorporated (Sony Group Corp.)
• Inventors: Asokan, Ramanathan, Johnson, Philip Marc
• Granted Patent: US 7,606,705 B2
• Time in Patent Office: Days
• US Class Current: 455/552.100
• CPC Class Codes: H04L 1/0014 by adapting the source coding
• CPC Class Codes: H04L 1/0038 Blind format detection for detection of modulation format H04L27/0012
• CPC Class Codes: H04L 1/0046 Code rate detection or code type detection H04L1/0038 takes precedence; detection of the data rate H04L25/0262; for packet format H04L1/0091
• CPC Class Codes: H04L 1/0054 Maximum-likelihood or sequential decoding, e.g. Viterbi, Fano, ZJ algorithms
• CPC Class Codes: H04L 1/0075 Transmission of coding parameters to receiver H04L1/0023 takes precedence
• CPC Class Codes: H04L 1/20 using signal quality detector
• CPC Class Codes: H04L 1/201 Frame classification, e.g. bad, good or erased frame indication per se H04L1/0082

Abstract

Disclosed is a system and method for channel decoding speech frames in a receiver capable of multiple (M) codec modes, wherein channel encoded speech frames include an inband bit portion and a speech portion. An inband bit decoder decodes the inband bit portion (700) of a received frame to obtain confidence levels associated with each of the M codec modes. Using these confidence levels, the codec modes are ordered from most to least likely. The speech frame is then decoded by a channel decoder using the most likely codec mode (704). A frame determination check (720) is performed to determine the quality of the decoded speech frame. If the decoded speech frame is determined to be of poor quality, then the channel decoding process is repeated using the next most likely codec mode (736) corresponding to the next highest inband bit decoding confidence level. This process is repeated until a good speech frame is decoded or some exit criteria is reached.

Claims

1. A method of channel decoding speech frames in a receiver capable of multiple (M) codes modes, said channel encoded speech frames comprised of an inband bit portion and a speech portion, said method comprising:

(a) decoding the inband bit portion of a received frame to obtain confidence levels associated with each of the M codec modes 700,

(b) choosing the most likely codec mode based on the highest confidence level to channel decode the speech portion 704;

(c) decoding the speech portion 310 of the received frame using the chosen speech codec mode;

(d) performing a frame determination check 720 to determine the quality of the decoded speech frame; and

(e) if the decoded speech frame is determined to be of poor quality, then choosing the next most likely codec mode 736 corresponding to the next highest inband bit decoding confidence level and repeating steps (c) through (e).

2. The method of claim 1 wherein steps (c) through (e) are repeated for a maximum number of iterations (N) 732, where N≦

M.

3. The method of claim 1 wherein steps (c) through (e) are repeated so long as the confidence level for the inband bit decoding with respect to the current codec mode is above a threshold confidence level 802.

4. The method of claim 2 wherein the maximum number of iterations N is determined prior to choosing the most likely codec mode to decode the speech portion based on the highest confidence level (902, 904, 704).

5. The method of claim 4 wherein the maximum number of iterations (N) is set to the number of codec modes that exceed a threshold confidence level 902.

6. A method of channel decoding speech frames in a receiver capable of multiple (M) codec modes, said channel encoded speech frames comprised of an inband bit portion and a speech portion, said method comprising:

calculating a plurality of inband decode metrics, one for each speech codec mode 1002;

partially decoding speech data for each speech codec mode 1004;

determining the most likely speech codec mode 1006 based upon the partially decoded speech data and the calculated inband decode metric data; and

resuming decoding of the speech data 1008 using the most likely speech codec mode.

7. A receiver for channel decoding speech frames, said receiver capable of multiple (M) codec modes, said channel encoded speech frames comprised of an inband bit portion and a speech portion, said receiver comprising:

an inband bit decoder for;

decoding the inband bit portion of a speech frame to obtain confidence levels associated with each of the M codec modes 700; and

choosing the most likely speech codec mode based on the highest confidence level to decode the speech portion 704; and

a channel decoder coupled with the inband bit decoder for;

decoding the speech portion 310 of the received frame using the chosen codec mode;

performing a frame determination check 720 to determine the quality of the decoded speech frame; and

if the decoded speech frame is determined to be of poor quality, then choosing the next most likely codec mode 736 corresponding to the next highest inband bit decoding confidence level and running the channel decoder on the received frame again.

8. The receiver of claim 7 wherein the channel decoder is run for a maximum number of iterations (N) 732, where N≦

M.

9. The receiver of claim 7 wherein the channel decoder is run so long as the confidence level for the inband bit decoding with respect to the current codec mode is above a threshold confidence level 802.

10. The receiver of claim 8 wherein the maximum number of iterations N is determined prior to the inband bit decoder choosing the most likely codec mode to decode the speech portion based on the highest confidence level (902, 904, 704).

11. The receiver of claim 10 wherein the maximum number of iterations (N) is set to the number of codes modes that exceed a threshold confidence level 902.

12. A receiver for channel decoding speech frames, said receiver capable of multiple (M) codec modes, said channel encoded speech frames comprised of an inband bit portion and a speech portion, said receiver comprising:

an inband bit decoder for;

calculating a plurality of inband decode metrics, one for each codec mode 1002; and

a channel decoder for;

partially decoding speech data for each codec mode 1004;

determining the most likely codec mode 1006 based upon the partially decoded speech data and the calculated inband decode metric data; and

resuming decoding of the speech data 1008 using the most likely codec mode.