Optimal antenna array receiver design and evaluation for fast Rayleigh flat fading environments

We develop an approach for using an antenna array for tracking fast Rayleigh flat fading channels and suppressing cochannel interference. A general autoregressive (AR) filter is used to model fast flat fading channels, making it possible to characterize the temporal variation of the channels and evaluate its effect on the receiver structure and performance. The optimal array receiver structure that minimizes the probability of error for BPSK signals is derived, which includes a Kalman filter to predict fading channels. A simple expression for the probability of error is also derived for the optimal receiver. In particular, we analyze the case with an AR-1 shaping filter and identical independent fading channels. An irreducible probability of error is shown to exist due to the prediction error of multiple channels. Another interesting observation from the study is that the diversity gain with m antenna elements in the presence of k interferences is usually greater than (m-k), i.e. m antennas with k interferences always perform better than (m-k) antennas without interference. Simulations are carried out to verify the theoretical analysis.