Patent ID: 8059744

Claim:
A method comprising: at a first communication device, receiving a transmission at a plurality of antennas from a second communication device, wherein the transmission uses some but not all frequency subbands within a frequency band space; recovering baseband signals carried in the frequency subbands in the received transmission; computing a channel covariance matrix from the baseband signals in the frequency subbands with respect to the plurality of antennas of the first communication device; computing uplink beamforming weights from the baseband signals in the frequency subband from the channel covariance matrix; computing a spatial projection of the uplink beamforming weights; computing frequency domain variations in the channel between the first communication device and the second communication device based on difference in time of arrival of signals from different direction of arrivals at the plurality of antennas of the first communication device; computing a downlink spatial projection for a given frequency subband from the frequency domain variations and the spatial projection of the uplink beamforming weights; and computing downlink beamforming weights from the downlink spatial projection, wherein the downlink beamforming weights are for use by the first communication device when beamforming a downlink transmission via the plurality of antennas of the first communication device to the second communication device.