Patent ID: 7813442
Filing Date: 2010-10-12
Classification: H04L

Abstract:
1. A method comprising: receiving an incoming signal communicated across a multiple-input-multiple-output (MIMO) communication channel; sampling the incoming signal to generate a sampled signal; transforming the sampled signal from a time-domain signal to a frequency-domain signal by use of a Fast Fourier Transform (FFT) to generate a transformed sampled signal; determining a carrier frequency offset (CFO) from the sampled signal, in which preambles to be utilized for channel estimation are communicated in symbols over more than one time period and in which the symbols have subcarriers that are orthogonal, wherein a first symbol communicated during a first time period and a second symbol communicated during a second time period have a substantially flat phase response across respective subcarriers, but have a phase difference between the first symbol and the second symbol that results in a CFO phase shift between the first and second symbols that is due to a difference in time between the first and the second time periods; calculating the phase difference between the first and second symbols at one subcarrier; applying the calculated phase difference to all subcarriers; applying the transformed sampled signal and calculated phase difference to modify a weighting matrix that is employed to perform channel estimation to determine an estimate of the communication channel, the weighting matrix modified for all subcarriers to account for the CFO phase shift; and performing channel estimation using the modified weighting matrix to correct for the CFO phase shift between the first and second time periods.