Minimum BER FIR receiver filters for DS-CDMA systems

The problem of multi-user receiver design in direct sequence single antenna-code division multiple access (DS-CDMA) uplink networks is studied over multipath channels. An exact expression for the bit error rate (BER) is derived and an algorithm is proposed for finding the finite impulse response (FIR) receiver filters such that the exact BER of the active users is minimized. The algorithm performance is found for scenarios with different channel qualities, receiver filter lengths, near-far effects, and channel mismatch. The proposed FIR receiver structure has significant better BER with respect to E_b/N₀ and near-far resistance than the corresponding minimum mean square error (MSE) filters