Iterative turbo decoder with decision feedback equalizer for signals transmitted over multipath channels

The problem of detecting turbo encoded signals transmitted over multipath channels is addressed and a new structure of turbo decoder combined with decision feedback equalizer (DFE) is presented. In this structure, a DFE is implemented in the turbo decoding iteration loop such that the DFE and a modified turbo decoder, which generates both information and parity bits, operate in a mutual support fashion. Simulation results are presented for a rate 1/3 turbo code, which has been selected for 3G mobile systems, with binary phase-shift keying (BPSK) modulation, transmitted over multipath channels having severe frequency distortion. Compared with a turbo equalizer, where soft extrinsic information is calculated from the detection and decoding steps and passed between equalizer and turbo decoder, the new structure is much simpler but efficient.