Analytical BER performance in spatial multiplexing MIMO systems

In this paper, we investigate the average bit error rate (BER) performance of spatial multiplexing MIMO systems with CSI at both sides of the link. Such systems result from the use of a multiple beamforming strategy that exploits the channel eigenmodes or, in other words, from the use of joint transmit-receive linear signal processing techniques in multiantenna systems. Since an analytical closed-form expression for the average BER of the multiple beamforming scheme is difficult to be found, we derive an approximation of the BER performance for high signal-to-noise ratio (SNR) assuming a Rayleigh flat fading channel. In the high SNR regime, the BER versus SNR curve can be characterized in terms of two key parameters: the array gain and the diversity gain. Thus, the proposed analysis offers a simple approach to determine the average performance of the multiple beamforming scheme.