Patent ID: 8194720

Claim:
A wireless communication system which performs data transmission using spatially multiplexed streams from a first terminal including N antennas to a second terminal including M antennas, N being an integer of 2 or more and M being an integer of 1 or more, the system comprising: notifying means for notifying the first terminal of a maximum dimension N max at a time of estimating a channel matrix of the second terminal, wherein N max is an integer of M or less; training means for transmitting a sounding packet including training sequence for exciting a channel corresponding to the maximum dimension N max from the first terminal to the second terminal, the sounding packet being transmitted in a staggered format including first and second sections, the first section having a first format corresponding to a format of one of the streams, and the second section having a second format, wherein the sounding packet is transmitted in the staggered format for temporally dividing: a training signal part used for a space division process of a data part; and a training signal part for exciting a channel of a spatial dimension larger than or equal to the number of streams of data; channel matrix estimation means for dividing the training sequence received by the antennas of the second terminal into N max or less streams and estimating the channel matrix having M rows and N max or less columns, wherein the channel matrix is estimated based on a determination that a number of antennas N of the first terminal is greater than a number of antennas M of the second terminal; beamforming information feedback means for preparing beamforming information necessary for calculating a transmission weight matrix for beamforming in the first terminal on the basis of the channel matrix estimated in the second terminal and feeding back the beamforming information from the second terminal to the first terminal; transmission weight matrix setting means for setting the transmission weight matrix for beamforming at a time of transmitting data from the first terminal to the second terminal on the basis of the beamforming information fed back from the second terminal to the first terminal; and beamforming means for performing beamforming in transmission signals of the antennas of the first terminal using the transmission weight matrix for beamforming when a data packet is transmitted from the first terminal to the second terminal.