Receive Antenna Array Strategies in Fading and Interference: An Outage Probability Comparison

We explore tradeoffs between different reception strategies of multiple receive antennas in fading channels with co-channel interference (CCI). Our tradeoff analysis is based on outage probability. We assume the signal from the desired user at the receive antenna array to be affected by Rice, Nakagami or Rayleigh fading, while CCI signals are assumed to experience Rayleigh fading. We provide closed-form analytical expressions for the outage probability of different diversity schemes, such as maximal ratio combining (MRC) and optimum combining (OC), and also for interference cancellation (IC) based on antenna beamsteering, which steers nulls in the array radiation pattern in the direction of the strongest interferers. Our analysis provides a unified framework for studying outage probability of different multiple-antenna reception strategies, and our closed- form expressions are easily computed, facilitating a performance comparison under a range of operating conditions. Our numerical results show that IC yields significantly better performance than MRC if the system is interference-limited and the number of dominant interferers is lower than the number of receive antennas, or when the output SINR is low. In addition, when the background noise can be neglected, we provide numerical results for MRC and OC when the signals from the desired user at the different receive antennas are arbitrarily distributed.