Patent ID: 7778211

Claim:
A method comprising: receiving at a plurality of antennas of an antenna array of a base station an uplink transmission that is transmitted from a mobile station, wherein the uplink transmission is transmitted in an uplink channel that comprises a plurality of sub-channels, each of which comprises a plurality of subcarriers; computing uplink channel coefficients for the uplink channel from the received uplink transmission at the base station; computing for each antenna in the antenna array of the base station, one or more coefficients for a time-domain channel impulse response function from the uplink channel coefficients; computing a frequency response of the uplink channel from the time-domain channel impulse response function for each antenna; calculating a spatial signature of the uplink channel from the frequency response; and computing a downlink beamforming weighting vector for use when making a downlink transmission via the antenna array of the base station on a downlink channel to the mobile station from the spatial signature of the uplink channel, wherein the downlink channel comprises a plurality of downlink sub-channels that share few or no frequency sub-carriers with the plurality of uplink sub-channels.