US Patent 7813442 MIMO channel estimation in presence of carrier frequency offset

A technique to determine carrier frequency offset (CFO) phase shift and perform channel estimation for symbols of a signal communicated across a multiple-input-multiple-output (MIMO) communication channel, in which preambles utilized for channel estimation are sent over more than one time block. Because the transmission of preambles used for channel estimation are sent over multiple time blocks, a CFO phase shift that is flat across tones of an OFDM signal is experienced between preambles of the two time blocks. Upon detection of the CFO phase shift, a weighting matrix used for channel estimation is modified to account for the CFO phase shift, in order to perform the channel estimation with correction for the CFO phase shift.