Low complexity message passing-based receiver design for Wiener phase-noise channels

This letter concerns low complexity receiver design for Wiener phase-noise channels, where the variance of the additive white Gaussian noise (AWGN) is unknown. By representing the system with a factor graph, both the variational message passing and the sum-product message passing are used to achieve efficient joint decoding, phase noise estimation, and AWGN precision (the reciprocal of AWGN variance) estimation. Compared with the state-of-the-art receiver, the proposed receiver is able to achieve the same performance with much lower complexity.