MAP SELECTION DIVERSITY DFE FOR INDOOR WIRELESS DATA COMMUNICATIONS

Indoor high-speed wireless data networks encounter signal fading and d elay-spread multipath propagation, Hence, the realization of low error rate transmission requires measures to combat the performance degrada tion due to both signal fading and intersymbol interference (ISI), Rec eiver diversity has been known to be an efficient way of coping with t he Former problem, while adaptive equalization could be used to mitiga te the effects of the latter, Incorporation of receiver diversity with adaptive equalization is therefore desirable. In this paper, we propo se a novel selection diversity approach with an adaptive decision-feed back equalizer (DFE). In this method, selection is done on a symbol-by -symbol basis such that the output of the branch with the lowest estim ated a posteriori probability of error is used as the final decision. This final (and hence more reliable) decision is used to adapt the DFE fur all diversity branches. It is shown in this paper that the propos ed selection rule is optimal for selection diversity in the maximum a posteriori probability (MAP) sense, A very simple selection metric can be derived from this selection rule and practical ways of computing t he selection metric are also presented, Simulation results show that t he proposed method is very efficient. It is capable of achieving almos t the same performance as an optimal [least squares (LS)], but computa tionally intensive, combining diversify approach, Furthermore, at are average bit error rate (BER) of 10(-4), a gain of approximately 1.25 d B can be achieved over a previously proposed selection diversity equal ization approach.