Exact Outage Probability of Opportunistic DF Relay Systems With Interference at Both the Relay and the Destination Over Nakagami- $m$ Fading Channels

In this paper, we investigate the outage behavior of a dual-hop opportunistic decode-and-forward (DF) relay system with cochannel interference (CCI) at both the relay and the destination. The source-relay and relay-destination channels and the interferers´ channels at both the relay and the destination nodes are assumed to follow Nakagami-m distribution. Exact closed-form expressions for the outage probability for both independent nonidentically distributed (i.n.d.) and independent identically distributed (i.i.d.) cases of interferers´ channels are derived in this paper. Furthermore, the system behavior at high SNR values is studied via deriving the asymptotic outage probability, and hence, the diversity order and the coding gain are characterized. Our results show that the cochannel interferers do not reduce the diversity gain of the system; instead, they degrade the outage performance by affecting the coding gain of the system. The accuracy of the analytical results is supported by Monte Carlo simulations.