Equalization of indoor fading channels with differentially coherent demodulation

Abstract

We employ a fractionally spaced decision feedback equalizer for indoor fading channels and give the relevant analytical and simulated performance results in terms of Doppler frequency. An upper limit is determined for the channel variations which can be tracked by the equalizer. Also, the effect of error propagation on the performance is evaluated. Finally, a nonlinear decision-based equalizer compatible with differentially coherent PSK is proposed. This equalization scheme is appropriate whenever conventional equalizers are not able to track channel phase variations. Our simulation results indicate that, for channels with spectral nulls, equalization will be achieved successfully with the proposed scheme, whereas linear equalizers, either with coherent or non-coherent detection, fail.