Phase Noise Mitigation in Serially Concatenated Continuous Phase Modulation with the Sum-Product Algorithm

We use the sum-product algorithm to handle the problem of phase noise (PN) in the detection of a serially concatenated continuous phase modulated system. Although optimal performance is not assured due to the loopy nature of the factor graph describing the problem, as well as simplifications made in the algorithm development, simulations show that significant performance gains are possible, and the gap between systems with and without PN can be reduced to about 1 dB using the proposed method. The increase in complexity compared to ignoring PN is small, and no periodic pilot symbols are inserted within a code word, although we assume the availability of a phase-locking mechanism to set the initial phase offset to a small range around zero. We use a different Gaussian approximation from what has been previously proposed, and this results in a less complex algorithm