Patent ID: 7474611

Claim:
A method of estimating a channel response from a received signal that comprises two or more different carriers in an Orthogonal Frequency Division Multiplexing (OFDM) communications system, the method comprising: for each of the carriers, determining a rotation amount that is at least in part a function of a frequency separation between two adjacent carriers, a delay spread of the channel, and a position of the carrier relative to other carriers within the received signal; processing the received signal and thereby generating a processed signal, whereby the processing includes processing with a Fast Fourier Transform; prior to performing frequency interpolation as part of a channel estimation process, rotating the carrier components of the processed signal by corresponding ones of the rotation amounts; and estimating the channel response by performing the channel estimation process at least in part on the rotated processed signal, wherein determining the rotation amounts and rotating the carrier components of the processed signal by corresponding ones of the rotation amounts comprise: for each of the carriers, generating an initial rotation amount that is at least in part a function of the frequency separation between two adjacent carriers, a delay spread of the channel, and a position of the carrier relative to other carriers within the received signal; rotating the carrier components of the processed signal by corresponding ones of the rotation amounts; and iteratively adjusting the initial rotation amounts based on a comparison of rotated signals on different pilot frequencies with one another and then again rotating the previously rotated processed signal by the adjusted rotation amount until an iteration termination condition is satisfied.