Outage Performance of Multi-Antenna Relay Cooperation in the Absence of Direct Link

Cooperation among relays can achieve spatial diversity, which improves the link quality in a wireless network. In this letter, we investigate the performance of an infrastructure based multi-antenna relay network in the absence of a direct link. A closed form expression of outage probability has been derived, when the cooperating relays and destination coherently combine the received signals. The effect of number of relay antennas and relay placement on the system performance have also been studied.