Patent ID: 7936839

Claim:
A method of determining channel estimates for pilot signals transmitted from different transmit antennas in a MIMO communication system wherein said pilot signals are spread over an extended period spanning multiple symbol periods, the method comprising: despreading the received signal over each symbol period of an extended measurement period spanning multiple ones of the extended periods using a common spreading sequence to obtain combined channel estimates for the pilot signals over each symbol period of the extended measurement period; and determining individual channel estimates for the pilot signals over each symbol period of the extended period based on the combined channel estimates by evaluating a system of linear equations based on the combined channel estimates, wherein evaluating the system of linear equations comprises evaluating: c 1,comb =c 1 +c 2 c 2,comb =c 1 +Δ 1 −c 2 −Δ 2 c 3,comb =c 1 +2Δ 1 +c 2 +2Δ 2 c 4,comb =c 1 +3Δ 1 −c 2 −3Δ 2 , where c 1,comb , c 2,comb , c 3,comb , and c 4,comb represent the combined channel estimates over different symbol periods of the extended measurement period, c 1 and c 2 represent the individual channel estimates over one symbol period for a first and a second pilot signals, respectively, and Δ 1 and Δ 2 represent channel estimate differences between symbol periods for the first and the second pilot signals, respectively.