Mobile Communications Using Source-Selected Multi-Antenna AF Relays Over Dual-Hop Nakagami-m Channels

This paper presents a scheme for dual-hop amplify-and-forward multi-antenna, multi-relay selection over Nakagami-m fading channels. A source-selected best relay performs maximal ratio combining on received data, applies variable gain, and then uses beamforming to transmit to a destination device. Such a configuration is beneficial for end-to-end communication using single antenna mobile terminals with a multi-antenna relay infrastructure. Closed form expressions for performance metrics are derived that cater for arbitrary number of relays, arbitrary number of receive and transmit antennas and different fading parameters. Results are verified through simulation. Furthermore, the influence of multiple antennas, the effects of fading, power imbalance between hops, and the beneficial impact of additional relays are explored.