Constrained minimum-BER multiuser detection

Abstract

A new linear multiuser detector that directly minimizes the bit-error rate (BER) subject to a set of reasonable constraints is proposed. It is shown that the constrained BER cost function has a unique global minimum. This allows us to develop an efficient barrier Newton method for finding the coefficients of the proposed detector using information about timing, amplitudes, channels, and the signature signals of all users. Although the new detector cannot be shown to be optimal among linear multiuser detectors without the constraints imposed, extensive simulations demonstrate that it achieves the lowest BER. Furthermore, in some cases, the BER of the proposed detector can be significantly lower than that of the decorrelating and MMSE detectors. Index Terms-Bit-error rate minimization, interior-point numerical optimization, multiuser detection.

Minimum BER Receiver Filters with Block Memory for Uplink DS-CDMA Systems

“…Only a sketch of proof is given: the receiver filters can be shown to be global optima following the same procedure that was used in [11, proof of Theorem 1] or of [8,Proposition 1] for each of the N MISO receiver filters with block memory.…”

“…It is assumed that the system is synchronized. Various works (see, e.g., [8][9][10]), have minimized BER with respect to the receiver parameters in a perfect synchronized system when the receiver is modeled by a memoryless block receiver filter. In [11], they have studied minimum BER receiver filter for single-user SISO systems and no transmitter filter was considered.…”