APPARATUS AND METHODS FOR JOINTLY DECODING MESSAGES BASED ON APRIORI KNOWLEDGE OF MODIFIED CODEWORD TRANSMISSION

• US 20080279312A1
• Filed: 07/23/2008
• Published: 11/13/2008
• Est. Priority Date: 01/23/2006
• Status: Active Grant

• Current Assignee: Google Technology Holdings LLC (Alphabet Inc.)
• Original Assignee: Motorola, Inc. (Motorola Solutions, Inc.)
• Inventors: Buckley, Michael E., Smolinske, Jeffrey C., STEWART, KENNETH A., Peyrusse, Oliver
• Granted Patent: US 8,462,890 B2
• Time in Patent Office: Days
• US Class Current: 375/340
• CPC Class Codes: H03M 13/2933 using a block and a convolutional code H03M13/2957 takes precedence
• CPC Class Codes: H03M 13/3769 using symbol combining, e.g. Chase combining of symbols received twice or more
• CPC Class Codes: H03M 13/41 using the Viterbi algorithm or Viterbi processors
• CPC Class Codes: H03M 13/6306 Error control coding in combination with Automatic Repeat reQuest [ARQ] and diversity transmission, e.g. coding schemes for the multiple transmission of the same information or the transmission of incremental redundancy H03M13/3761, H03M13/3769 and H03M13/635 take precedence
• CPC Class Codes: H04L 1/0045 Arrangements at the receiver end
• CPC Class Codes: H04L 1/0064 Concatenated codes
• CPC Class Codes: H04L 1/0072 Error control for data other than payload data, e.g. control data
• CPC Class Codes: H04L 1/1835 Buffer management

Abstract

A method and apparatus for jointly decoding a first and second message is disclosed. The signaling scenario illustrated by FIG. 1 and using the codeword properties defined herein, the various embodiments may combine multiple messages under the hypothesis that the value of a message portion corresponding any subsequent observed transmission is different. Accordingly a first buffer may store the first observed message frame (509) and a second buffer may sum the LLR'"'"'s of subsequent observed frames (513).

In the embodiments disclosed, two decoding hypotheses are required only; a first where the two buffers are combined directly (513) and a second where the difference codeword bit LLR'"'"'s of the first buffer (509) are inverted before combining with those of the second buffer (519). A maximum of N transmissions is allowed by the receiver (523), after which a decoding failure is declared.

Claims

1. A method of operating a receiver comprising:

jointly decoding a first codeword of a first message and second codeword of a second message having a known difference from said first message, utilizing said known difference.

2. The method of claim 1, further comprising:

hypothesizing said difference between said first message and said second message prior to said jointly decoding.

3. The method of claim 2, wherein the step of hypothesizing said difference further comprises:

initially hypothesizing that said first message and said second message are identical, prior to said jointly decoding; and

subsequently hypothesizing that at least one bit is different between said first message and said second message, prior to said jointly decoding.

4. The method of claim 2, wherein the step of hypothesizing said difference further comprises:

initially hypothesizing that at least one bit is different between said first message and said second message, prior to said jointly decoding; and

subsequently hypothesizing that said first message and said second message are identical, prior to said jointly decoding.

5. The method of claim 1, further comprising:

performing an arithmetic operation with a first set of probabilistic values corresponding to said first codeword,

a second set of probabilistic values corresponding to said second codeword, and

said known difference, prior to said jointly decoding.

6. The method of claim 1, further comprising:

performing an arithmetic operation with a first set of probabilistic values corresponding to said first codeword,

a second set of probabilistic values corresponding to said second codeword, and

said known difference, subsequent to said jointly decoding.

7. The method of claim 1, further comprising:

decoding said first codeword and said second codeword using a convolutional decoder and a Fire decoder.

8. The method of claim 2 further comprising:

deriving a first decoder input component from said first codeword wherein said first codeword has a linear encoding;

deriving a second decoder input component from said second codeword wherein said second codeword has said linear encoding; and

modifying a portion of said second decoder input component based on said hypothesizing said difference, and said linear encoding.

9. The method of claim 8, wherein the step of modifying a portion of said second decoder input component based on said hypothesizing said difference, and said linear encoding, further comprises:

negating said portion of said second decoder input component.

10. The method of claim 9, wherein said first decoder input component is a first set of log likelihood ratio values and said second decoder input component is a second set of log likelihood ratio values, further comprising:

combining said first set of log likelihood ratio values with said second set of log likelihood ratio values to obtain a combined decoder input.

11. The method of claim 10, further comprising:

inputting said combined decoder input to a convolutional decoder and a Fire decoder.

12. A wireless receiver comprising:

a demodulation circuitry configured to demodulate a first message and a second message having a known difference from said first message;

a decoding circuitry coupled to said demodulation circuitry configured to;

hypothesize said difference between said first message and said second message; and

jointly decode said first message and said second message using said hypothesized difference.

13. The wireless receiver of claim 12, wherein said decoding circuitry is further configured to:

initially hypothesize that said first message and said second message are identical; and

subsequently hypothesize that at least one bit is different between said first message and said second message.

14. The wireless receiver of claim 12, wherein said decoding circuitry is further configured to:

initially hypothesize that at least one bit is different between said first message and said second message; and

subsequently hypothesize that said first message and said second message are identical.

15. The wireless receiver of claim 12, wherein said decoding circuitry is further configured to perform an arithmetic operation with a first set of probabilistic values corresponding to said first message, a second set of probabilistic values corresponding to said second message, and said known difference, prior to said jointly decoding.

16. The wireless receiver of claim 12, wherein said decoding circuitry is further configured to perform an arithmetic operation with a first set of probabilistic values corresponding to said first message, a second set of probabilistic values corresponding to said second message, and said known difference, subsequent to said jointly decoding.

17. The wireless receiver of claim 12, further comprising:

a first memory buffer coupled to said decoding circuitry configured to store data associated with said first message; and

a second memory buffer coupled to said decoding circuitry configure to store data associated with said second message.

18. The wireless receiver of claim 17, wherein said decoding circuitry further comprises:

a first decoding circuitry;

an interleaver coupled to said first decoding circuitry; and

a second decoding circuitry coupled to said interleaver and said first decoding circuitry.

19. The wireless receive of claim 18, wherein said first decoding circuitry is a convolutional decoder and said second decoding circuitry is a Fire decoder.