Sequence detection on fading channels without explicit channel estimation

A maximum-likelihood sequence detector with no explicit extraction of channel state information (MLSD-NCSI) for diversity reception of quadrature-amplitude-modulated (QAM) signals over a flat fading channel is derived. Its performance improves with the sequence length L, but the computational complexity also increases with L. To implement MLSD-NCSI with a practical complexity for an increasing L, we propose to apply the trellis-search algorithm with a linear complexity, or pilot-symbol-assisted block detector, whose complexity is fixed by using pilot symbols in block detection. Their bit error probabilities are obtained via simulations.