An adaptive receiver for frequency selective fading channels

Adaptive reception of binary data over a frequency selective slow Rayleigh fading communication channel, through wideband signaling, using spectral spreading codes is considered. Based on the likelihood ratio test, an estimator correlator receiver structure is developed. The receiver structure includes the effects of estimation errors, which are usually neglected. The estimator is a Wiener-Hopf filter, and for reasonable SNRs the estimator can be realized as simple linear averaging, which is asymptotically optimal. In practice, the linear averaging may have to be modified by using exponential weights to prevent runaway due to decision errors. The receiver performance is a function of estimation error variance, which depends on the channel SNR, multipath spread and profile, fade rate, and multiuser interference, when used for SSMA (satellite-switched multiaccess) applications.<>