An Efficient Rank Adaptation Algorithm for Cellular MIMO Systems with IRC Receivers

Multiple transmit and receive antennas introduce additional degrees of freedom, which can be used to increase the number of spatial channels between a transmitter-receiver pair. Alternately, the additional degrees of freedom can be used to improve the interference resilience property with the help of linear interference rejection combining (IRC) receivers. Typically, rank adaptation algorithms are aimed at balancing the trade-off between increasing the spatial gain, and improving the interference resilience property. In this paper, we propose an efficient and computationally effective rank adaptation algorithm based on an estimate of the mean signal-to-interference-plus-noise ratio (SINR) at an IRC receiver; wherein, we use results from random matrix theory to derive the expression for the mean post-IRC SINR in the presence of interferers with unequal powers. The performance of the proposed algorithm is analysed through system level simulations. The results are found to be comparable to the optimum performance, and match closely to that of a more complex existing rank adaptation method.