A first device explicitly sounds a wireless channel with respect to a second device even when the second device cannot sound all the antenna/transmit paths of the first device. The first device has a first plurality of antennas and corresponding transmitters and the second device has a second plurality antennas and corresponding receivers. The first device wirelessly transmits a plurality of sounding frames to the second device such that at least one of the first plurality of antennas is kept constant across the plurality of sounding frames. The first device receives from the second device at least one feedback message containing channel matrix information derived from reception of the sounding frames at the second plurality of antennas of the second device. The first device derives a full wireless channel estimate between the first plurality of antennas of the first device and the second plurality of antennas of the second device.