Linear precoding in coordinated multicell systems with amplify-and-forward relaying

The paper studies the linear precoding problem in coordinated multicell MIMO half-duplex amplify-and-forward (AF) relay-aided systems. Based on the idea of the Blahut-Arimoto algorithm, an iterative algorithm is proposed to obtain a suboptimal solution of the non-convex weighted sum rate maximizing problem. The proposed method involves the following three steps in each iteration: updating the posterior conditional probability using the closed-form solution, updating the source precoding matrices through solving a simple quadratically constrained quadratic program (QCQP) problem and updating the relay precoding matrices one by one by an efficient bisection search method. This algorithm increases the weighted sum rate monotonically in each iteration until convergence. Simulation results are presented to demonstrate the effectiveness of our method.