Adaptive Equalization in Digital Communications

This chapter presents Simulink models that incorporate adaptive equalization. Specific topics include: linear least mean square (LMS) equalizers with binary phase‐shift keying (BPSK) in dispersive multipath channels and additive white Gaussian noise (AWGN); linear LMS equalizer with quadrature phase shift keying (QPSK) in a channel with Intersymbol Interference (ISI); decision feedback equalizers (DFEs) with BPSK in a dispersive multipath channel and AWGN; and recursive least squares (RLS) equalizers with BPSK in a dispersive multipath channel, AWGN, and Rayleigh fading. Decision feedback equalizers were shown to offer better performance than linear LMS equalizers. For fading channels with rapid time variation, an RLS equalizer offers the best performance. In all cases, the final performance is dictated by the selection of relevant parameters such as the scale factor in LMS equalizers and the forgetting factor in RLS equalizers.