Sub-optimal turbo-detection for coded 8-PSK signals over ISI channels with application to EDGE advanced mobile system

A turbo-detector concept assuring a favorable tradeoff between performance and complexity is investigated for the novel radio access scheme at enhanced data rates for GSM evolution (EDGE). The high level modulation employed in EDGE (8-PSK) precludes MAP or MLSE turbo-detection, and consequently, computationally efficient sub-optimum solutions have to be considered. A turbo-detector based on a generic SISO delayed decision-feedback sequence estimator (DDFSE) is shown to be a very promising candidate, so long as we couple it with a discrete-time allpass pre-filter turning channel impulse response into minimum phase.