On the capacity of relay-assisted wireless MIMO channels

We study the impact of multiple amplify-and-forward relays on the capacity of wireless MIMO channels. For wireless networks with one source/destination pair (equipped with multiple antennas) and several single-antenna amplify-and-forward relays we determine the compound (over two time slots) channel matrix of the relay-assisted MIMO channel. We derive the asymptotic eigenvalues of the compound channel matrix by letting the number of transmit and receive antennas go to infinity (large-array limit). Then the asymptotic ergodic capacity of the amplify-and-forward transmission scheme is determined for Rayleigh and Rice fading. The results serve as tight approximation for a finite number of transmit and receive antennas and are accurate in the large-array limit.