Adaptive cancellation of self-interference in full-duplex wireless with transmitter IQ imbalance

The cancellation of in-band self-interference caused by simultaneous transmission and reception is an essential issue to realize full-duplex wireless communication. In this paper, we investigate the impact of transmitter IQ imbalance on self-interference cancellation. From our results, it is shown that the residual self-interference in the presence of transmitter IQ imbalance has considerably large power. To cancel it, a baseband cancellation signal generated by widely linear (WL) filtering is proposed and the optimal WL filters are derived. For practical implementation, we also propose an adaptive algorithm based on the augmented complex least mean square method to directly obtain the WL filters. Simulation results demonstrate the validity of the proposed algorithm.