Decorrelating detector with diversity combining for single user frequency-selective rayleigh fading multipath channels

Diversity combining techniques are applied in mobile radio communications as a means of performance improvement in a fading multipath environment. Adaptive equalizers which incorporate diversity combining were shown to combat intersymbol interference (ISI) caused by multipath provided that the fading is sufficiently slow. However, for fast fading rates, noncoherent techniques are often desirable. In this paper, we examine the performance of several coherent and noncoherent detectors that make use of diversity combining. In particular, the decorrelating filter is shown to provide reliable performance for a frequency-selective Rayleigh fading multipath channel with ISI. Numerical and simulation results are presented for a channel with two independent Rayleigh fading paths. Signal design issues which arise in the implementation of the decorrelating detector and the zero-forcing equalizer are discussed.