Unified MMSE estimation for GMSK signals with turbo codes

A new way of implementation of MMSE channel estimator for a GMSK signals with Turbo code over multipath fading channels is proposed in the paper. From the recent research results, it is clear that the usage of Turbo Codes with GMSK modulation is highly desirable because some signal processing modules in the receiver can be reused for both turbo decoder and equalization, and thus the receiving complexity can be reduced. Channel estimator is one of the modules that are required by the equalizer and the Turbo code decoder. In this paper we present an estimation technique, used for both GMSK equalization and Turbo decoder (SOVA/Log-MAP) over the multipath fading channel. The proposed MMSE estimator replaces the matched filters that are usually applied at the receiver end. The simulation results show that unified MMSE estimator gives us an edge over the disadvantages of the matched filter and conventional isolated estimators, such that the bit error rate performance is improved and the distorted data could be easily retrieved from the estimation technique.