Channel estimation for amplify-and-forward relaying with spatially correlated antennas

This paper proposes an optimal training design for an amplify-and-forward (AF) relay system in which the source, relay and destination are all equipped with multiple antennas. Examined is the scenario when spatial correlation exists among the multiple antennas employed at each node in the system and such information is properly taken into account in the training design. The training design problem is formulated as a convex optimization problem which can be efficiently solved with the iterative bisection procedure. Simulation results demonstrate the performance advantage of the proposed training design for the linear minimum mean-squared-error (LMMSE) channel vector estimation over the training design for the LMMSE channel matrix estimation.