A Message-Passing Receiver for OFDM-Based Self-Interference-Limited Networks

In this paper, we develop a reliable bandwidth-efficient solution for coherent reception in networks prone to self-interference. Our primary focus is on orthogonal-frequency-division-multiplexing (OFDM)-based amplify-and-forward (AF) two-way relaying, where each source node suffers from reradiation of its own signal. An important issue is the superposition of the desired and interfering signals, which makes the channel estimation task difficult, particularly for varying channel coefficients. To address this challenging problem, we introduce a factor graph model of the estimation and detection problem at hand. Exploiting the conditional independence between unknown variables in the factor graph, an efficient message-passing algorithm, which performs joint Bayesian channel estimation, self-interference mitigation, and decoding, is derived. Simulation results show that the performance of the proposed method is close to that given by perfect knowledge of the channel for the target and interfering signals, even with limited training overhead.