Correction of in phase-quadrature imbalance in the presence of multipath fading

The presence of in-phase/quadrature (I/Q) imbalance in a dual branch receiver gives rise to signal distortion. If the incoming signal is also corrupted by multipath fading, then the task of correcting or compensating for these two forms of distortion becomes technically very challenging. This paper proposes an adaptive approach which involves first correcting for the I/Q imbalance before the signal is compensated for the effect of multipath fading. Estimations of the I/Q imbalance and channel parameters are carried out with the aid of a common reference signal. Computer simulations have verified the effectiveness of the proposed scheme. In this case, the receiver suffers from frequency-flat I/Q imbalance of 20% gain and 5° phase deviations. Also, the incoming 64-QAM signal is assumed to have undergone a 6-path propagation.