Outage probability analysis of dual-hop multiple antenna fixed-gain AF relay systems with interference

This paper presents an analytical investigation on the outage performance of dual-hop multiple antenna fixed-gain amplify-and-forward relay systems in the presence of co-channel interference. Exact closed-form analytical expressions for the outage probability of the systems are derived. Moreover, simple outage probability approximations at the high signal to noise ratio regime are provided, and the diversity order achieved by the systems are characterized. Our results suggests that the fixed-gain AF relaying schemes only achieves diversity order of one. Moreover, it is beneficial to put the multiple antennas at the source or destination node rather than at the relay node.