On the use of oversampling in adaptive receivers for frequency selective Rayleigh fading channels

In this work, we investigate Maximum Likelihood Sequence Estimation (MLSE) of data sequences transmitted over time-varying frequency-selective Rayleigh fading channels and consider adaptive receivers which realize joint data estimation and channel tracking utilizing Per-Survivor Processing (PSP) techniques. In order to obtain a sufficient statistics for data detection, the received signal is oversampled with respect to the symbol rate. Accordingly, a time-discrete channel model with fractional spacing, with respect to the symbol interval, is assumed and an algorithm which performs fractionally-spaced PSP-based channel tracking is analyzed. We show that receivers which employ this algorithm outperform traditional adaptive receivers based on one sample per symbol interval. Two samples per symbol interval are shown to be sufficient to attain the optimal performance for these receivers.