Average Error Probability of MIMO Diversity Systems in the Presence of Multiple Interferers

The performance of MIMO systems is investigated in a flat-fading scenario limited by cochannel interference. It is assumed that both the desired and interferer signals are Rayleigh-faded. We analyze the average probability of bit error of M-ary quadrature amplitude modulation in the presence of multiple independent interferers. The results are applicable to systems employing open-loop transmit diversity, and maximal ratio combining with coherent demodulation. We study the interaction between the number of equal power interferers and the spatial diversity order. The results indicate that the gain introduced by receive antennas is more robust to interference than the spatial diversity gain introduced by multiple transmitters. Moreover, we also show the effect of a varying number of interfering sources when spatial diversity is being exploited. Furthermore we derive a closed form expression of the asymptotic behavior of the average probability of bit error. This expression is then used to analytically explain the relation between number of interferers and diversity.