Iterative receiver for amplify-and-forward relay networks with unknown noise correlation

For amplify-and-forward relay networks, we propose an iterative scheme to estimate channel and detect information symbols for the multi-antenna destination in spatially correlated noise. The equivalent channel coefficients and noise covariance are estimated by expectation-maximization algorithm. In addition, we discuss the initialization of iteration and analyze the modified Cramér-Rao bound to show the performance of the proposed iterative estimation. Moreover, on the basis of the structure of the proposed iterative estimator, a joint channel estimation and detection receiver is also provided. Finally, simulation results show that the proposed channel estimator and receiver can achieve the optimal performances in amplify-and-forward relay networks with unknown noise correlation.