Diversity signal reception via soft decision combining

The problem of diversity signal reception using quantized data is considered. This problem arises in situations where multiple receivers are employed over a geographically broad area. We propose a method for the design of the quantizers that are used by the receiver to make soft decisions. This quantizer minimizes the mean-squared error between the quantizer output and the log-likelihood ratio associated with the receiver observation. The soft decisions are then combined at a central location to yield the final decision. Our quantizers are then applied to the coherent detection of a BPSK signal over Rayleigh fading channels. Simulation results show that using coarse quantizers yields close to optimum performance.