Doubly iterative MMSE equalization of binary continuous phase modulation

In this paper, a suboptimal, but low-complexity technique is introduced to achieve the turbo equalization for binary continuous phase modulation (CPM). The proposed receiver consists of a soft-information aided minimum mean squared error equalizer (MMSE) at its front-end, and the soft-input soft-output demodulator and decoder blocks at its back-end. The receiver is doubly iterative with outer iterations for equalization and inner iterations for CPM demodulation and channel decoding at each outer iteration. Turbo processing overcomes the performance degradation due to suboptimality, where the iterations do not result in high computational complexity as it is in the conventional methods. Simulation results are furnished for performance comparisons.