A new reduced-complexity adaptive PSP-MLSE receiver for GSM/EDGE systems

A new adaptive reduced-complexity MLSE receiver based on per-survivor processing (PSP-MLSE) and a decision feedback equalizer (DFE) for GSM/EDGE system with 8PSK modulation is proposed. The initial channel impulse response (CIR) is estimated by the LS algorithm with a mid-amble and updated by the LMS algorithm during data transmission. The proposed scheme handles the first part of the sampled CIR by the PSP-MLSE and the rest by the DFE for complexity reduction. Instead of the conventional global DFE (decision per sample), the local DFE (decision per state/survivor) is suggested to reduce error propagation. A good tradeoff between performance and complexity, by retaining the PSP-MLSE for good performance and using the local DFE for intersymbol interference cancellation, is obtained. Computer simulations indicate that the PSP-MLSE with the local DFE is clearly superior to that with the global DFE, especially in severe ISI channels.