Constrained minimum-BER multiuser detection

Abstract

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.

Adaptive minimum error-rate filtering design: A review

“…In the past decade, significant advances have been made in the design of adaptive minimum BER (MBER) filtering for a variety of communication applications, including classical single-user channel equalisation [5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20], multiuser detection in codedivision multiple-access (CDMA) systems [21][22][23][24][25][26][27][28][29][30], adaptive beamforming assisted receiver for multiple-antenna aided systems [31][32][33][34][35][36][37][38][39], space-time equalisation assisted multiuser detection for spacedivision multiple-access (SDMA) induced multipleinput multiple-output (MIMO) systems [40][41][42][43][44], and orthogonal frequency division multiplexing (OFDM) and other multi-carrier systems [45][46][47][48][49][50]. The ...…”

Multiple antenna aided OFDM employing minimum bit error rate multiuser detection

“…In our previous discourse we assumed the explicit knowledge of the FDCHTF matrix H defined in (1). However, in practice H has to be determined on the basis of the channel impaired noisy value of x and hence a number of adaptive techniques have been proposed in [3][4][5] to this effect, which are also applicable to OFDM=SDMA. Fig.…”

“…However, as suggested in the context of either conventional channel equalisation [3] or in CDMA [4,5], a better strategy is to choose the linear detector's coefficients so as to directly minimise the error probability or bit error rate (BER), rather than the mean squared error (MSE), since minimising the MSE does not necessarily guarantee that the BER of the system is also minimised. Detectors that directly minimise the BER are referred to as minimum-BER (MBER) detectors [3][4][5]. Against this background, in this Letter, we contrive the MBER linear MUD designed for the uplink of an SDMA=OFDM system.…”

Error rates of capacity-achieving codes are convex

“…Consequently, when an optimization of a communication system is performed, either SER or BER often appears as the goal or constraint function. Examples include optimum power/rate allocation in spatial multiplexing systems (BLAST) [3], optimum power/time sharing for a transmitter and a jammer [4], rate allocation or precoding in multicarrier (OFDM) systems [5], optimum equalization [6], optimum multiuser detection [7], and joint Tx-Rx beamforming (precoding-decoding) in MIMO systems [8]. Symbol and bit error rates of the maximum likelihood (ML) detector have been extensively studied and a large number of exact or approximate analytical results are available for various modulation formats, for both non-fading and fading AWGN channels [9].…”