Particle swarm optimization assisted joint transmit/receive antenna combining for multiple relays in cooperative MIMO systems

This paper presents a novel relay resource utilization scheme that uses the particle swarm optimization (PSO) algorithm to jointly search the antenna combining (AC) matrices of multiple relays in cooperative MIMO systems. The relays use the AC matrices to weight and combine signals transmitted by the source node, and then forward the weighted signal to the destination node. As a result, the relays can reduce the number of radio frequency (RF) chains used by the transmit/receive antenna elements, and thereby lower the hardware costs of deploying RF chains. Furthermore, because there are fewer RF chains, the relays require less power than relays that use all the RF chains The results of computer simulations demonstrate that the proposed scheme outperforms the full RF-chain relay method and existing approaches in some scenarios.