Method and apparatus of cross-correlation with application to channel estimation and detection
View Patent ↗The present disclosure provides for a method and apparatus for efficient cross-correlation between a reference sequence and a received sequence in a wireless communication system. The reference sequence includes a concatenation of sign-adjusted sub-sequences, the sign adjustments determined by a first sign sequence of a set of sign sequences. For example, the reference sequence may be an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences. The received sequence is shifted to provide a plurality of time shifted sequences that are then cross-correlated with the sub-sequences to form a set of partial cross-correlations. The partial cross-correlations are sign-adjusted using the first sign sequence and combined to produce the cross-correlation between the reference sequence and the received sequence. The cross-correlations so produced may be used for channel signature (e.g. PHY-type) identification and/or channel impulse response estimation.
1. A method for determining a cross-correlation between a reference sequence and a received sequence in a wireless communication system, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, the method comprising:
oversampling the received sequence compared to a chip rate of the received sequence;
forming a plurality of parallel chip-rate phases from the oversampled received sequence;
cross-correlating the plurality of parallel chip-rate phases with the reference sequence to provide a plurality of correlations;
determining the phase of a strongest correlation of the plurality of correlations in accordance with a metric; and
processing the plurality of correlations dependent upon the phase of the strongest correlation.
2. The method of claim 1 , where the reference sequence comprises a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, and where cross-correlating the plurality of parallel chip-rate phases with the reference sequence to provide the plurality of correlations comprises:
shifting the received sequence to provide a plurality of time shifted sequences;
cross-correlating the plurality of time shifted sequences with sub-sequences of the set of sub-sequences to form a set of partial cross-correlations;
sign-adjusting the partial cross-correlations using the first sign sequence; and
combining the sign-adjusted partial cross-correlations to produce the cross-correlation between the reference sequence and the received sequence, where the cross-correlation is used by the wireless communication system to facilitate wireless communication.
3. The method of claim 1 , where the reference sequence comprises an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences.
4. The method of claim 1 , where processing the plurality of correlations comprises:
selecting a correlation of the plurality of correlations having the strongest metric.
5. The method of claim 1 , where processing the plurality of correlations comprises:
outputting the metric of the correlation of the plurality of correlations having the strongest metric.
6. The method of claim 1 , where processing the plurality of correlations comprises:
converting the parallel correlations to a serial correlation at the oversampled rate; and
sub-sampling the serial correlation dependent upon the phase of the strongest correlation of the plurality of correlations.
7. The method of claim 1 where the received sequence is received via a communication channel, the method further comprising:
estimating an impulse response of the communication channel from the cross-correlation between the reference sequence and the received sequence.
8. A method for determining a cross-correlation between a reference sequence and a received sequence in a wireless communication system, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, the method comprising:
shifting the received sequence to provide a plurality of time shifted sequences;
cross-correlating the plurality of time shifted sequences with sub-sequences of the set of sub-sequences to form a set of partial cross-correlations;
sign-adjusting the partial cross-correlations using the first sign sequence; and
combining the sign-adjusted partial cross-correlations to produce the cross-correlation between the reference sequence and the received sequence, where the cross-correlation is used by the wireless communication system to facilitate wireless communication,
where the reference sequence comprises an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences.
9. A system operable to determine a cross-correlation between a reference sequence and a received sequence in a wireless communication system, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatentated, the sign adjustments determined by a first sign sequence of a plurality of sign sequences, the system comprising:
a plurality of shift modules operable to shift the received sequence by an amount dependent upon the length of the sub-sequences to provide a plurality of shifted received sequences;
a plurality of correlators operable to form a plurality of partial cross-correlations by correlating a shifted received sequence with a sub-sequence of the set of sub-sequences; and
at least one combiner operable to adjust signs of the plurality of partial cross-correlations in accordance with the first sign sequence and sum the sign adjusted partial correlations to provide the cross-correlation between the reference sequence and the received sequence, where the cross-correlation is used by the wireless communication system
where the reference sequence comprises an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences.
10. The system of claim 9 , where the plurality of shift modules comprises a series cascade of shift modules each operable to shift the received sequence by the length of the sub-sequences.
11. An electronic device operable to determine a cross-correlation between a set of M reference sequences and a received sequence in a wireless communication system, each reference sequence of the set of reference sequences comprising a concatenation of sign-adjusted sub-sequences, the sign adjustments determined by a sign sequence of a set of M sign sequences, the system comprising:
a serial-to-parallel converter responsive to the received sequence, over-sampled at R times the chip rate of the received sequence, and operable to provide R phase-adjusted chip-rate sequences;
R chip-rate correlators, each operable to produce M chip-rate correlations between a phase-adjusted chip-rate sequence and the M reference sequences; and
M phase selectors, each responsive to R chip-rate correlations for a reference sequence of the M reference sequences and operable to select a chip-rate correlation for which a metric of the chip-rate correlation is maximized, where the chip-rate correlation selected facilitates wireless communication.
12. An electronic device comprising:
a receiver operable to recover a received sequence from a received communication signal;
a correlator operable to determine a cross-correlation between a reference sequence and the received sequence, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence of a plurality of sign sequences, the correlator comprising:
a plurality of shift modules operable to shift the received sequence by an amount dependent upon a length of the sub-sequences to provide a plurality of shifted received sequences;
a plurality of partial correlators operable to form a plurality of partial cross-correlations by correlating a shifted received sequences with a sub-sequence;
at least one combiner operable to adjust signs of the plurality of partial cross-correlations in accordance with the first sign sequence and sum the sign adjusted partial correlations to provide the cross-correlation between the reference sequence and the received sequence; and
a processor operable to process the received sequence dependent upon the cross-correlation between the reference sequence and the received sequence for use during wireless communication,
where the reference sequence comprises an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences.
13. An electronic device for determining a cross-correlation between a reference sequence and a received sequence in a wireless communication system, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, the device comprising a chip-rate correlator that comprises:
a plurality of shift modules operable to shift the received sequence to provide a plurality of time shifted sequences;
a plurality of correlators operable to form a set of partial cross-correlations by cross-correlating the plurality of time shifted sequences with sub-sequences of the set of sub-sequences; and
a combiner operable to adjust the signs of the plurality of partial cross-correlations using the first sign sequence and combine the sign adjusted partial cross-correlations to produce the cross-correlation between the reference sequence and the received sequence, where the cross-correlation is used by the wireless communication system to facilitate wireless communication.
14. A non-transitory computer-readable medium having processor-executable instructions that, when executed by a processor, cause the processor to perform a method for determining a cross-correlation between a reference sequence and a received sequence in a wireless communication system, the reference sequence comprising a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, the method comprising:
oversampling the received sequence compared to the chip rate of the received sequence;
forming a plurality of parallel chip-rate phases from the oversampled received sequence;
cross-correlating the plurality of parallel chip-rate phases with the reference sequence to provide a plurality of correlations;
determining the phase of a strongest correlation of the plurality of correlations in accordance with a metric; and
processing the plurality of correlations dependent upon the phase of the strongest correlation.
15. The non-transitory computer-readable medium of claim 14 , where the reference sequence comprises a set of sub-sequences that have been sign-adjusted and concatenated, the sign adjustments determined by a first sign sequence, and where, in the method performed by the processor, cross-correlating the plurality of parallel chip-rate phases with the reference sequence to provide the plurality of correlations comprises:
shifting the received sequence to provide a plurality of time shifted sequences;
cross-correlating the plurality of time shifted sequences with sub-sequences of the set of sub-sequences to form a set of partial cross-correlations;
sign-adjusting the partial cross-correlations using the first sign sequence; and
combining the sign-adjusted partial cross-correlations to produce the cross-correlation between the reference sequence and the received sequence, where the cross-correlation is used by the wireless communication system to facilitate wireless communication.
16. The non-transitory computer-readable medium of claim 14 , where the reference sequence comprises an alternating concatenation of sign-adjusted Golay complementary pair sub-sequences.