Blind maximum likelihood sequence estimation for fading channels

Maximum a posteriori (MAP) sequence estimation for channels with intersymbol interference (ISI) has previously required knowledge of the channel sampled impulse response (SIR). Generally the SIR coefficients are determined via least mean squares (LMS) or recursive least squares (RLS) estimation algorithms. For many unguided media channels such as mobile radio and high frequency (HF) radio exhibiting a time-varying SIR, these estimators must be adaptive. Often they fail to track adequately and are a major source of detector deterioration. A novel blind maximum likelihood sequence estimation (BMLSE) formulation without the need for external channel SIR estimation is proposed and implementation issues discussed. Its performance is simulated and compared to the contemporary technique, MLSE with external LMS channel estimation