MMSE WL Equalizer in Presence of Receiver IQ Imbalance

Abstract

In this correspondence, with reference to the transmission over a linear time-dispersive channel, we address the problem of the in-phase and quadrature-phase (IQ) imbalance compensation when a single-carrier modulation scheme is used. Low-cost fabrication technologies and high data-rate transmissions render the conventional receivers very sensitive to the imperfections of their analog stage and, hence, proper countermeasures need to be adopted. Since the IQ imbalance renders the received signal rotationally variant, we propose to resort to the widely linear (WL) filtering in the synthesis of the receiver. More specifically, the synthesis of the WL receiver is performed by assuming perfect knowledge of the IQ imbalance parameters, but a new blind algorithm for IQ imbalance compensation, which outperforms the existing blind technique, is also proposed.