Detection for OFDM-AF Relay Systems under Gaussian Mixture Noise with Imperfect CSI

Signal detection for orthogonal frequency-division multiplexing (OFDM) amplify-and-forward (AF) relay systems, under imperfect channel state information (CSI), is studied. Also, different from the published works, non-Gaussian noise, which always exists in practical wireless communication systems, is investigated. In order to avoid underestimating the noise model, the optimization structure over the key parameters of Gaussian mixture noise, CSI and data is constructed. After that, a closed form solution in iterative manner is obtained using the theory of variational message passing (VMP) based on the factor graph. Simulation proves the effectiveness of the proposed approach.