Limiting SIR Performance of MMSE Receivers for Large MIMO Systems with Spatial Multiplexing and Non-Constant Modulus Modulations

This paper is concerned with the limiting signal-to-interference-plus-noise (SIR) performance of MMSE receivers for large MIMO systems with spatial multiplexing and higher order non-constant modulus modulations. Using random matrix theory, we derive the limiting SIR performance of a suboptimal MMSE receiver when applied to large MIMO systems with unequally-powered users. It has been proven that the limiting SIR converges to a deterministic value when K and N go to infinity with K/N=y being a constant, where K is the number of transmit antennas and N is the number of receive antennas. The limiting SIR result is then used to quantify the SIR loss for different MMSE receivers applied to MIMO systems with non-constant modulus modulations. Numerical results have shown that loss in limiting SIR is small for the suboptimal receiver as compared to optimal receiver