Recovering symbols in a communication receiver
View Patent ↗Methods of recovering symbols and corresponding communication receivers including dual receivers configured to perform the method, where the method comprises: sampling a received signal that includes interference to provide received samples; determining a plurality of high power symbols and determining alternate symbols for a portion of the plurality of high power symbols based on the received samples and based on known training symbols; and deriving a sequence of recovered symbols corresponding to the received samples based on the received samples and augmented training symbols, the augmented training symbols comprising the known training symbols augmented by the plurality of high power symbols with one or more alternate symbols replacing a corresponding one or more high power symbols.
1. A method of recovering symbols in a communication receiver, the method comprising:
sampling a received signal that includes interference to provide received samples;
determining a plurality of high power symbols and alternate symbols for a portion of the plurality of high power symbols based on the received samples and based on known training symbols; and
deriving a sequence of recovered symbols corresponding to the received samples based on the received samples and augmented training symbols, the augmented training symbols comprising the known training symbols augmented by the plurality of high power symbols with one or more alternate symbols replacing a corresponding one or more high power symbols.
2. The method of claim 1 wherein the determining a plurality of high power symbols and the determining alternate symbols further comprises;
finding estimated coefficients for an interference cancellation filter based on a portion of the received samples and known training symbols, the portion of the received samples corresponding to the known training symbols;
calculating estimated symbols based on the received samples and on the estimated coefficients; and
selecting the plurality of high power symbols from the estimated symbols and selecting the alternate symbols for the portion of the plurality of high power symbols.
3. The method of claim 2 wherein the finding estimated coefficients further comprises:
finding potential coefficients for an interference cancellation filter for each delay of a range of delays using a corresponding portion of the received samples, the corresponding portion of the received samples based on a respective delay and the known training symbols; and
selecting, from the potential coefficients, the estimated coefficients for the interference cancellation filter in accordance with an error function.
4. The method of claim 1 further comprising determining a channel parameter associated with the received samples and compensating the received samples in accordance with the channel parameter.
5. The method of claim 4 wherein the determining a channel parameter further comprises determining a delay including:
finding potential coefficients for an interference cancellation filter for each delay of a range of delays using a corresponding portion of the received samples, the corresponding portion of the received samples based on a respective delay and the known training symbols; and
selecting, from the potential coefficients, the estimated coefficients for the interference cancellation filter in accordance with an error function, the estimated coefficients being a function of the delay.
6. The method of claim 4 wherein the determining a channel parameter further comprises determining a gain including:
finding potential coefficients for an interference cancellation filter for each gain of a range of gains using a corresponding portion of the received samples, the corresponding portion of the received samples based on the known training symbols; and
selecting, from the potential coefficients, the estimated coefficients for the interference cancellation filter in accordance with an error function, the estimated coefficients being a function of the gain.
7. The method of claim 4 wherein the determining a channel parameter further comprises determining a frequency offset including:
finding potential coefficients for an interference cancellation filter for each frequency offset of a range of frequency offsets using a corresponding portion of the received samples, the corresponding portion of the received samples based on a respective frequency offset and the known training symbols; and
selecting, from the potential coefficients, the estimated coefficients for the interference cancellation filter in accordance with an error function, the estimated coefficients being a function of the frequency offset.
8. The method of claim 1 wherein the determining a plurality of high power symbols further comprises:
finding estimated coefficients for an interference cancellation filter, the estimated coefficients based on a corresponding best delay;
calculating a sequence of estimated symbols based on the received samples and the estimated coefficients; and
sorting, based on power, the sequence of estimated symbols to provide the plurality of high power symbols.
9. The method of claim 8 wherein the determining alternate symbols for a portion of the plurality of high power symbols further comprises: for each of the portion of the plurality of high power symbols, finding, based on Euclidean distance from known symbols, a corresponding alternate symbol.
10. The method of claim 1 wherein the deriving a sequence of recovered symbols corresponding to the received samples based on the received samples and augmented training symbols, further comprises iteratively deriving different sequences of potential recovered symbols using different sequences of augmented training symbols and selecting the sequence of recovered symbols from the different sequences of potential recovered symbols in accordance with an error function.
11. The method of claim 10 further comprising:
replacing one or more high power symbols in a first sequence of augmented training symbols with a corresponding one or more alternate symbols to form a second sequence of augmented training symbols; and
deriving a new sequence of potential recovered symbols using the second sequence of augmented training symbols.
12. The method of claim 11 further comprising:
comparing a new error for the new sequence of potential recovered symbols with an old error for a previous sequence of potential recovered symbols derived using the first sequence of augmented training symbols to provide a best error;
replacing an additional high power symbol with a corresponding alternate symbol in a sequence of augmented training symbols that corresponds to the best error; and
repeating the deriving, comparing, and replacing processes until all alternate symbols have been attempted.
13. The method of claim 1 wherein the sampling a received signal that includes interference to provide received samples further comprises sampling a received signal from a plurality of receivers to provide the received samples with samples from each of the plurality of receivers.
14. A communication receiver configured to recover symbols from a radio frequency signal that includes interference, the communication receiver comprising:
one or more receiver front ends configured to provide, respective, received signals with interference, the received signals corresponding to the radio frequency signal;
one or more sampler functions coupled, respectively, to the one or more receiver front ends, and configured to sample the, respective, received signals and provide received samples from each of the one or more receiver front ends; and
a demodulator configured for:
determining a plurality of high power symbols and determining alternate symbols for a portion of the plurality of high power symbols based on the received samples and based on known training symbols; and
deriving a sequence of recovered symbols corresponding to the received samples based on the received samples and augmented training symbols, the augmented training symbols comprising the known training symbols augmented by the plurality of high power symbols with one or more alternate symbols replacing a corresponding one or more high power symbols.
15. The communication receiver of claim 14 wherein the demodulator configured for determining a plurality of high power symbols and the determining alternate symbols is further configured for:
finding estimated coefficients for an interference cancellation filter based on a portion of the received samples and known training symbols, the portion of the received samples corresponding to the known training symbols;
calculating estimated symbols based on the received samples and on the estimated coefficients; and
selecting the plurality of high power symbols from the estimated symbols and selecting the alternate symbols for the portion of the plurality of high power symbols.
16. The communication receiver of claim 15 wherein the demodulator further configured for finding estimated coefficients is further configured for:
finding potential coefficients for an interference cancellation filter for each delay of a range of delays using a corresponding portion of the received samples, the corresponding portion of the received samples based on a respective delay and the known training symbols; and
selecting, from the potential coefficients, the estimated coefficients for the interference cancellation filter in accordance with an error function.
17. The communication receiver of claim 14 wherein the demodulator configured for determining a plurality of high power symbols and determining alternate symbols for a portion of the plurality of high power symbols is further configured for:
finding estimated coefficients for an interference cancellation filter, the estimated coefficients based on a corresponding best delay;
calculating a sequence of estimated symbols based on the received samples and the estimated coefficients;
sorting, based on power, the sequence of estimated symbols to provide the plurality of high power symbols; and
finding, for each of the portion of the plurality of high power symbols, a corresponding alternate symbol based on Euclidean distance from known symbols.
18. The communication receiver of claim 14 wherein the demodulator configured for deriving a sequence of recovered symbols corresponding to the received samples based on the received samples and augmented training symbols, is further configured for iteratively deriving different sequences of potential recovered symbols using different sequences of augmented training symbols and selecting the sequence of recovered symbols from the different sequences of potential recovered symbols in accordance with an error function.
19. The communication receiver of claim 18 wherein the demodulator is further configured for:
replacing one or more high power symbols in a first sequence of augmented training symbols with a corresponding one or more alternate symbols to form a second sequence of augmented training symbols; and
deriving a new sequence of potential recovered symbols using the second sequence of augmented training symbols.
20. The communication receiver of claim 19 wherein the demodulator is further configured for:
comparing a new error for the new sequence of potential recovered symbols with an old error for a previous sequence of potential recovered symbols derived using the first sequence of augmented training symbols to provide a best error;
replacing an additional high power symbol with a corresponding alternate symbol in a sequence of augmented training symbols that corresponds to the best error; and
repeating the deriving, comparing, and replacing processes until all alternate symbols have been attempted.