Space-time decision feedback equalisation using a minimum bit error rate design for single-input multiple-output channels

A minimum bit error rate (MBER) decision feedback equaliser (DFE) designed for single-input multiple-output (SIMO) systems employing a quadrature phase shift keying (QPSK) modulation scheme is proposed. It is shown that this MBER design is superior over the standard minimum mean square error DFE in the SIMO scenario considered, in terms of the achievable system bit error rate. A sample-by-sample adaptive implementation of this MBER DFE is derived, which is referred to as the least bit error rate (LBER) algorithm. It is shown that for SIMO systems using a QPSK scheme, the LBER algorithm has a similar computational complexity as the simple least mean square (LMS) algorithm. Simulation results demonstrate that the proposed adaptive LBER-based DFE outperforms the adaptive LMS-based DFE, in both stationary and fading cases.