SYSTEM AND METHOD FOR DECODING A MESSAGE USING A PRIORI INFORMATION

1. A method for decoding digital data received by a correspondent device over a communication channel, the data including a component corresponding to a plurality of values unknown to the correspondent device and a component corresponding to one or more values known a priority the correspondent device, at least one of the one or more values known a priori by the correspondent device stored in memory of the correspondent device, the method comprising:

(a) the correspondent device retrieving from memory the at least one of the one or more known values;

(b) the correspondent device applying a statistical measure using the at least one of the one or more known values to estimate the location of the component corresponding to the one or more known values; and

(c) a decoder of the correspondent device using the one or more known values and the estimated location of the component corresponding to the one or more known values in decoding the data.

2. The method of claim 1 wherein prior to step (a), the decoder first decode the data without the estimated location and without the one or more known values, and subsequently performs steps (a) to (c) only if a decoding error is detected.

3. The method of claim 2 wherein said statistical measure is a sliding correlation.

4. The method of claim 3, wherein the sliding correlation is applied in real-time as the data is received by the correspondent device.

5. The method of claim 3 further comprising the step of (d) said decoder decoding the data using the estimated location of the component corresponding to the one or more known values as the actual location of the component corresponding to the one or more known values.

6. The method of claim 5 further comprising the step of using the sliding correlation to estimate another possible location of the component corresponding to the one or more known values, and wherein if the correspondent device detects an error in the data decoded in step (d), then repeating steps (c) and (d) using the another possible location of the component corresponding to the one or more known values.

7. The method of claim wherein said decoding comprises trellis-based decoding, and wherein the one or more known values is used to set at least one state in a trellis-based decoding algorithm.

8. A computer readable medium having stored thereon computer readable instructions for decoding digital data received by a correspondent device over a communication channel, the data including a component corresponding to a plurality of values unknown to the correspondent device and a component corresponding to one or more values known a priori by the correspondent device, at least one of the one or more values known a priori by the correspondent device stored in memory of correspondent device, the computer readable instructions comprising instructions for:

(a) retrieving from memory the at least one of the one or more known values;

(b) applying a statistical measure using the at least one of the one or more known values to estimate the location of the component corresponding to the one or more known values; and

(c) using the one or more known values and the estimated location of the component corresponding to the one or more known values in decoding the data in a decoder.

9. The computer readable medium of claim 8 wherein said computer readable instructions further comprise instructions for: prior to step (a), the decoder first decoding the data without the estimated location and without the one or more known values, and subsequently performing steps (a) to (c) only if a decoding error is detected.

10. The computer readable medium of claim 9 wherein said statistical measure is a sliding correlation.

11. The computer readable medium of claim 10 wherein said instructions further comprise instructions for (d) decoding the data using the estimated location of the component corresponding to the one or more known values as the actual location of the component corresponding to the one or more known values.

12. The computer readable medium of claim 11 wherein said instructions further comprise instructions for using the sliding correlation to estimate another possible location of the component corresponding to the one or more known values, and wherein if the correspondent device detects an error in the data decoded in step (d), then repeating steps (c) and (d) using the another possible location of the component corresponding to the one or more known values.

13. The computer readable medium of claim 11 wherein said decoding comprises trellis-based decoding, and wherein the one or more known values is, used to set at least one state in a trellis-based decoding algorithm.

14. A correspondent device in a communication system configured to decode digital data received over a communication channel in the communication system, the data including a component corresponding to a plurality of values unknown to the correspondent device and a component corresponding to one or more values known a priori by the correspondent device, the correspondent device comprising:

a memory for storing at least one of the one or more values known a priori by the correspondent device;

a statistical module for applying a statistical measure using the at least one of the one or more known values to estimate the location of the component corresponding to the one or more known values; and

a decoder configured to use the one or more known values and the estimated location of the component corresponding to the one or more known values in decoding the data.

15. The correspondent device of claim 14 wherein the decoder is configured to first decode the data-without the estimated location and without the one or more known values, and only if a decoding error is detected, the decoder uses the one or more known values and the estimated location in decoding the data.

16. The correspondent device of claim 15 wherein the statistical module is sliding correlator configured to perform a sliding correlation.

17. The correspondent device of claim 16 wherein the sliding correlator is configured to perform the sliding correlation in real-time as the data is received by the correspondent device.

18. The correspondent device of claim 16 wherein the decoder is further configured to decode the data using the estimated location of the component corresponding to the one or more known values as the actual location of the component corresponding to the one or more known values.

19. The correspondent device of claim 18 wherein the sliding correlator is further configured to estimate another possible location of the component corresponding to the one or more known values, and wherein if the correspondent device detects an error in the data decoded, then the decoder is configured to again decode the data using the another possible location of the component corresponding to the one or more known values as the estimated location.

20. The correspondent device of claim 18 wherein said decoding comprises trellis-based decoding, and wherein the one or more known values is used to set at least one state in a trellis-based decoding algorithm.