Fine phase estimation for highly spectrally efficient communications
A receiver may process a received signal to generate a processed received signal. The receiver may generate, during a sequence estimation process, an estimate of a phase error of the processed received signal. The receiver may generate an estimate of a value of a transmitted symbol corresponding to the received signal based on the estimated phase error. The generation of the estimate of the phase error may comprise generation of one or more phase candidate vectors. The generation of the estimate may comprise calculation of a metric based on the one or more phase candidate vectors. The calculation of the metric may comprise phase shifting the processed received signal based on the estimated phase error resulting in a phase-corrected received signal. The calculation of the metric may comprise calculating a Euclidean distance based on the phase-corrected received signal and one or more symbol candidate vectors.
1. A receiver comprising:
a sequence estimation circuit operable to:
receive a coarsely-phase-corrected signal having residual phase noise;
generate a symbol candidate sequence;
generate a phase candidate sequence corresponding to said residual phase noise;
calculate a sequence estimation metric for said symbol candidate sequence based on said symbol candidate sequence, said phase candidate sequence, and said coarsely-phase-corrected signal, wherein said sequence estimation circuit is operable to convolve said symbol candidate sequence with a filter response prior to said calculation of said sequence estimation metric; and
decide on a transmitted sequence of symbols based on said sequence estimation metric.
2. The receiver of claim 1 , further comprising an equalizer circuit operable to process a received signal to generate an equalized signal.
3. The receiver of claim 2 , wherein said equalizer is operable to adapt based on an output of said sequence estimation circuit.
4. The receiver of claim 2 , further comprising a carrier recovery circuit and phase correction circuit operable to generate said coarsely-phase-corrected signal.
5. The receiver of claim 4 , wherein said carrier recovery circuit is adapted based on an output of said sequence estimation circuit.
6. The receiver of claim 1 , wherein said filter response is based on pulse shaping filter of a transmitter from which a received signal which was processed to generate said coarsely-phase-corrected signal originated.
7. The receiver of claim 1 , wherein said filter response is based on an input filter of said receiver.
8. The receiver of claim 1 , wherein said sequence estimation metric is a Euclidean distance.
9. A method comprising:
in a receiver:
receiving, by a sequence estimation circuit, a coarsely-phase-corrected signal having residual phase noise;
generating, by said sequence estimation circuit, a symbol candidate sequence;
generating, by said sequence estimation circuit, a phase candidate sequence corresponding to said residual phase noise;
calculating, by said sequence estimation circuit, a sequence estimation metric for said symbol candidate sequence based on said symbol candidate sequence, said phase candidate sequence, and said coarsely-phase-corrected signal;
convolving, by said sequence estimation circuit, said symbol candidate sequence with a filter response prior to said calculating said sequence estimation metric; and
deciding, by said sequence estimation circuit, on a transmitted sequence of symbols based on said sequence estimation metric.
10. The method of claim 9 , further comprising processing, by an equalizer of said receiver, a received signal, said processing resulting in an equalized signal.
11. The method of claim 10 , comprising adapting said equalizer based on an output of said sequence estimation circuit.
12. The method of claim 10 , generating, by a carrier recovery circuit and phase correction circuit of said receiver, said coarsely-phase-corrected.
13. The method of claim 12 , further comprising adapting said carrier recovery circuit based on an output of said sequence estimation circuit.
14. The method of claim 9 , wherein said filter response is based on pulse shaping filter of a transmitter from which a received signal which was processed to generate said coarsely-phase-corrected signal originated.
15. The method of claim 9 , wherein said filter response is based on an input filter of said receiver.
16. The method of claim 9 , wherein said sequence estimation metric is a Euclidean distance.