Nearly optimal linear transceiver design for amplify-and-forward MIMO multiple-relay systems under MMSE criterion

SUMMARYIn this paper, we consider amplify‐and‐forward multiple‐input multiple‐output multiple‐relay systems, where all the nodes have multiple antennas. For enhancing link reliability, we address the problem of designing optimal linear transceiver to minimize the mean squared error (MSE) of symbol estimations subject to the total relay transmit power constraint. This problem is highly complex and has not been solved in the literature. We first simplify this optimization problem to one that takes a singular value vector and a unitary matrix as optimization variables. Then based on the analyses for the simplified problem, we develop an iterative algorithm consisting of one boundary optimization and one unitary matrix constrained optimization. We show analytically that the proposed iterative algorithm always converges, and the MSE is monotonically decreasing from one iteration to the next. Finally, numerical results demonstrate the nearly optimal performance of the proposed scheme. Copyright © 2012 John Wiley & Sons, Ltd. In this paper, we present a new linear transceiver design method for MIMO multiple‐relay systems with the objective of minimizing the mean squared error (MSE) under the total relay transmit power constraint. We develop an iteration algorithm that consists of one boundary optimization and one unitary matrix constrained optimization and prove the convergence. Simulation results demonstrate that the proposed iterative algorithm converges rapidly and the MSE performance closes to the lower bound when the total relay power is moderate to high levels.