Performance analysis of non-linearly amplified M-QAM signals in MIMO channels

MIMO systems using multiple transmit and receive antennas on both ends of a linear wireless communications link are by now well studied. Several axes of these schemes have been explored with the underlying MIMO channel assumed linear. In this work, we investigate the effect of non-linearity in the MIMO channel. New results on symbol error rate performances of several M-QAM constellations in linear and non-linear MIMO channels are presented. The results show that for any MIMO configuration, performance degradation due to non-linearity reduces as the fading gets more severe, and for a particular fading channel, the degradation increases as the MIMO dimension is increased. Optimum ring-ratios for circular QAM constellations in MIMO channels are also reported, and compared with existing results where applicable.