Blind turbo equalization with EM algorithm and DPSK modulation

In digital communication systems, joint equalization and decoding at the receiver is called turbo equalization. Turbo equalization in case of unknown channel is known as blind turbo equalization. In this study, a new blind turbo equalization method is developed for digital communication systems using DPSK modulation. The reason for choosing DPSK is to remove phase ambiguity. Expectation-maximization (EM) algorithm is used to estimate the unknown channel. Differential decoding is not done alone at the receiver. Instead of this, super-trellis structure made up of differential encoder and ISI channel is exploited for resolving the problem of phase ambiguity. Performance of the proposed method is tested via computer simulations.