I/Q imbalance compensation in precoded MIMO-OFDMA systems

We study the selection of precoders for transmission on mirror carrier pairs in a multiple input multiple output orthogonal frequency division multiple access system, where transmitter and receiver I/Q imbalance cause inter-carrier interference. In I/Q aware precoding, the precoders on mirror carriers are jointly selected. Viable selection schemes for a matched filter receiver are addressed. We compare schemes that favour one of the mirror carriers to iterative line and gradient searches, maximizing the instantaneous sum rate, as well as to an I/Q interference alignment approach. It turns out that the I/Q-aware precoding significantly improves performance at high signal-to-noise ratio regime where I/Q interference dominates.