On the application of turbo equalizers in GSM compatible receivers

We discuss the application of iterative, decoding algorithms (turbo equalizer) to GSM data channels (TCH/F9.6). Although the turbo equalizer under realistic time-variant channel scenarios has a high potential, we only get a minor performance gain when compared to conventional soft-decision algorithms. Certain constraints of the GSM coding scheme prevent better results. We discuss the transition from a very simple data transmission model to a full GSM-compatible system and compare the resulting bit error rates (BER). We introduce a modified turbo equalizer structure which adapts to the pipelining interleaver.