Patent ID: 8406720

Claim:
A method comprising: receiving at M plurality of antennas of a first wireless communication device uplink transmission from a second wireless communication device, the uplink transmissions comprising groups of subcarriers; computing channel information from the received uplink transmissions; determining one or more trigonometric waveforms determined to approximate the channel information for each group of subcarriers using an iterative process comprising: setting an initial signal equal to an estimated channel information vector representing the channel information for a group of subcarriers; computing a power quantity for a range of time delay values based on the initial signal; determining a time delay value that yields a maximum of the power quantity; comparing the maximum with a threshold; when the maximum is greater than the threshold, computing a maximum trigonometric waveform using the time delay value that yields the maximum of the power quantity; computing an updated signal by subtracting a portion associated with the maximum trigonometric waveform; repeating computing the power quantity, determining the time delay value, comparing, computing the maximum trigonometric waveform and computing the updated signal for a maximum number of iterations corresponding to a maximum number of trigonometric waveforms or until the maximum of the power quantity is less than the threshold, to thereby produce a sequence of indices from the range of time delay values for one or more trigonometric waveforms; and computing a downlink beamforming weight vector at a given subcarrier by interpolation using the one or more trigonometric waveforms, wherein the downlink beamforming weight vector is for application to a signal to be transmitted via the M plurality of antennas of the first device to the second device.