Systems and methods for calculating frequency-localized adaptive beamformer weights using recursively weighted updating across subcarriers

1. A receiver comprising:

a plurality of antennas, the plurality of antennas configured to receive data streams in a frequency band spanning multiple subcarrier frequencies; and

a beamformer coupled to the plurality of antennas and configured to receive the data streams, the beamformer comprising a weight processor configured to calculate, for each subcarrier of the frequency band, a respective plurality of weights used to generate signals for transmission by or combine the signals received at respective ones of the plurality of antennas; and

wherein the weight processor is configured to calculate weights for a particular subcarrier at least in part by:

calculating a component for the particular subcarrier using contributions from each of a plurality of other subcarriers, wherein the component includes an inverse covariance matrix;

updating the inverse covariance matrix calculated for a previous subcarrier frequency using a weighted contribution of the inverse covariance matrix calculated for the previous subcarrier frequency; and

weighting the contributions from each of the plurality of other subcarriers in accordance with a distance of the other subcarriers from the particular subcarrier.

2. The receiver of claim 1 , wherein weighting the contributions of each of the other subcarriers comprises weighting the contributions in accordance with an exponential of a forgetting factor based on a respective subcarrier distance from the particular subcarrier.

3. The receiver of claim 1 , wherein the component comprises the inverse covariance matrix and the weight processor is configured to calculate weights for the particular subcarrier at least in part by:

calculating a least squares solution for the particular subcarrier using the inverse covariance matrix to provide the respective plurality of weights for the particular subcarrier.

4. The receiver of claim 3 , wherein calculating the component comprises updating the previously-calculated inverse covariance matrix to obtain the inverse covariance matrix.

5. The receiver of claim 1 , wherein the component comprises a cross-correlation vector.

6. The receiver of claim 5 , wherein calculating the component comprises updating a previously-calculated cross-correlation vector to obtain the cross-correlation vector.

7. The receiver of claim 1 , wherein the number of subcarriers is based on a subband of the frequency band.

8. The receiver of claim 1 , wherein the weight processor is configured to calculate the inverse covariance matrix for the particular subcarrier using the weighted components of each of the number of subcarriers in part by performing a direct matrix inversion (DMI) algorithm using the weighted components of each of the number of subcarriers.

9. The receiver of claim 1 , wherein the receiver is implemented in a processor of a remote node of a wireless network, the processor configured to execute instructions from a non-transitory computer-readable medium used to implement the beamformer.

10. A method comprising:

receiving radio frequency (RF) signals at a plurality of antennas in a range of subcarrier frequencies; and

at a beamformer, for each subcarrier frequency in the range of subcarrier frequencies, calculating for each subcarrier of the range of subcarrier frequencies, a respective plurality of weights, said calculating comprising:

updating a cross-correlation vector calculated for a previous subcarrier frequency using a weighted contribution of the cross-correlation vector calculated for the previous subcarrier frequency;

updating an inverse covariance matrix calculated for the previous subcarrier frequency using a weighted contribution of the inverse covariance matrix calculated for the previous subcarrier frequency; and

calculating the respective plurality of weights for a particular subcarrier utilizing an updated cross-correlation vector and an updated inverse covariance matrix for the particular subcarrier.

11. The method of claim 10 , wherein updating the weighted contribution of the cross-correlation vector and the weighted contribution of the inverse covariance matrix are each weighted by a forgetting factor.

12. The method of claim 10 , further comprising:

calculating a least squares solution for the particular subcarrier using the updated inverse covariance matrix to provide the respective plurality of weights for the particular subcarrier.

13. The method of claim 10 , wherein a number of the subcarriers corresponds to a subband of a frequency band.

14. The method of claim 10 , wherein the cross-correlation vector calculated for the previous subcarrier frequency itself includes a weighted contribution of another cross-correlation vector calculated for another subcarrier frequency.

15. The method of claim 14 , wherein the cross-correlation vector calculated for the another subcarrier frequency was weighted by a forget factor to obtain the cross-correlation vector for the previous subcarrier frequency, such that a contribution of the cross-correlation vector calculated for the another subcarrier frequency is weighted by a square of the forget factor to obtain the updated cross-correlation vector.

16. The method of claim 10 , wherein the inverse covariance matrix calculated for the previous subcarrier frequency itself includes a weighted contribution of another inverse covariance matrix calculated for another subcarrier frequency.

17. The method of claim 16 , wherein the inverse covariance matrix calculated for the another subcarrier frequency was weighted by the forgetting factor to obtain the inverse covariance matrix for the previous subcarrier frequency, such that a contribution of the inverse covariance matrix calculated for the another subcarrier frequency is weighted by a square of the forget factor to obtain the updated inverse covariance matrix.

18. The method of claim 10 , further comprising recursively calculating weights for subsequent subcarriers utilizing the updated cross-correlation vector, the updated inverse covariance matrix, or combinations thereof.

19. A method comprising:

receiving radio frequency (RF) signals at a plurality of antennas in a range of subcarrier frequencies; and

at a beamformer, for each subcarrier frequency in the range of subcarrier frequencies:

based at least in part on updating an inverse covariance matrix based on weighting an inverse cross-correlation matrix calculated for a subcarrier of a lower frequency, calculating for each subcarrier of the range of subcarrier frequencies, a first respective plurality of weights based on weighted contributions from calculations for subcarriers at lower frequencies;

calculating for each subcarrier of the range of subcarrier frequencies, a second respective plurality of weights based on weighted contributions from calculations for subcarriers at higher frequencies; and

combining the first respective plurality of weights with the second respective plurality of weights to obtain final weights for a particular subcarrier.

20. The method of claim 19 , wherein calculating the first respective plurality of weights comprises updating a cross-correlation vector based on weighting the cross-correlation vector calculated for the subcarrier of lower frequency.

21. The method of claim 19 , wherein calculating the first respective plurality of weights comprises updating the inverse covariance matrix based on weighting the inverse cross-correlation matrix calculated for the subcarrier of lower frequency.

22. The method of claim 21 , wherein said combining comprises averaging.