Combined MLSE/symbol-based-demodulation scheme for fading channels with and without delay spread

A demodulation receiver structure that gives desirable performance for fading channels with and without delay spread is proposed. Using a decision variable derived from the channel response estimate, the new scheme identifies the delay spread of the channel and performs either maximum-likelihood sequence estimation (MLSE) or symbol-based detection operation to demodulate the received signal. Particular application discussed is the IS-136 North American TDMA cellular standard operating at cellular and PCS frequency bands. Simulation results show that the BER performance of the combined receiver structure is virtually identical to the symbol-based detection performance for the flat fading channel and the MLSE performance for the two-ray fading channel