Patent ID: 8737533

Claim:
A method, for use in a communication receiver, of estimating in-phase/quadrature imbalance (IQ-imbalance) of a received Orthogonal Frequency Division Multiplexing signal (OFDM signal) comprising: transforming the received OFDM signal to a frequency domain, wherein the frequency domain comprises a plurality of sub-carrier frequencies, and the transformed received OFDM signal comprises symbols of a first type on one or more sub-carrier frequencies and symbols of a second type on one or more other sub-carrier frequencies, the symbols of the first type being pilot symbols and the symbols of the second type being symbols other than pilot symbols; and determining a channel estimate for at least one of the sub-carrier frequencies where the transformed received OFDM signal comprises a symbol of the first type; estimating the IQ-imbalance based on at least one of the symbols of the first type, the determined channel estimate for the sub-carrier frequency of the at least one symbol of the first type and information related to a corresponding mirror sub-carrier frequency associated with the at least one symbol of the first type, wherein the corresponding mirror sub-carrier frequency comprises a symbol of the second type, and wherein the information related to a corresponding mirror sub-carrier frequency associated with the at least one symbol of the first type comprises at least one of: an estimate of a transmitted information symbol on the corresponding mirror sub-carrier frequency and an estimated channel value for the corresponding mirror sub-carrier frequency; and a received symbol on the corresponding mirror sub-carrier frequency; and applying a bias-compensating scaling factor to the estimated IQ-imbalance or the channel estimate when the channel estimate is derived based on one or more symbols that do not contribute to the estimated IQ-imbalance.