Fractionally spaced blind maximum likelihood sequence detection over fast fading fractionally-spaced channels

Maximum likelihood sequence detection (MLSD) for channels with intersymbol interference has previously required estimation of the channel impulse response. Adaptive estimators often fail to track adequately and are a major source of detector deterioration. Symbol-spaced detectors are also sensitive to both the sample timing phase, φ_g, of the received signal and to channels with fractional multipath delay spread, t_m. A novel fractionally-spaced (FS) blind maximum likelihood sequence detection (BMLSD) formulation without the need for external channel estimation is proposed. The sensitivity of the FS BMLSD to both φ_g and t_m is investigated via simulation over several FS channels. The results indicate substantial improvement compared to the conventional symbol-spaced MLSD