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

Abstract

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, /spl phi//sub g/, of the received signal and to channels with fractional multipath delay spread, t/sub 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 /spl phi//sub g/ and t/sub m/ is investigated via simulation over several FS channels. The results indicate substantial improvement compared to the conventional symbol-spaced MLSD.