Turbo Equalization in Blind Receiver

A turbo equalizer can benefit from channel decoding gain by iteratively performing equalization and channel de-coding. Turbo equalization algorithms always need perfect knowledge of the channel response. In this paper, we propose a blind turbo equalization and iterative channel estimator scheme. A fractional super-exponential blind equalizer is used to provide timing recovery and the a priori information that the SISO equalizer and soft-decision directed channel estimator need in the first turbo iteration. In order to reduce complexity, a simplified computation of the equalizer´s extrinsic information for MPSK modulation is used. Simulation results show that the proposed algorithm works effectively for multi-level modulations over severe frequency selective channel.