Patent ID: 7499504

Claim:
A method of communications in a multi-carrier communication station comprising: receiving preambles through a multiple-input multiple-output channel transmitted by two or more transmit antennas, each preamble comprising training signals, one of the preambles comprising the training signals and a polarity-inverted version of the training signals; calculating sum and difference channel signals for each subcarrier of a plurality of subcarriers based on the received preambles; and determining channel coefficients of the multiple-input multiple-output channel from the sum and difference channel signals using a set of linear equations, wherein calculating sum and difference channel signals comprises: determining the sum channel signals for a first set of the subcarriers from the training signals; determining the difference channel signals for a second set of the subcarriers from the training signals; determining the sum channel signals for the second set of the subcarriers from the polarity-inverted version of training signals; and determining the difference channel signals for the first set of the subcarriers from the polarity-inverted version of training signals.