Outage Analysis of Multihop Relay Systems in Interference-Limited Nakagami- $m$ Fading Channels

In this paper, we study the outage probability of multihop transmission systems with amplify-and-forward (AF) and decode-and-forward (DF) relaying protocols operating over a Nakagami-m fading environment in the presence of cochannel interference. We consider the case of interference-limited relays with ideal AF relay gains based on the inverse of the fading amplitude of the desired signal in the previous link. For an arbitrary but fixed number of Nakagami-distributed interferers per hop, we derive a closed-form expression for the outage probability of an N-hop AF relaying system in terms of the multivariate Lauricella function F_B^(N) that can be evaluated with commonly available computer software. Moreover, the outage performance of an N-hop DF relaying system is also derived in closed form, and the two performances are compared. Simulation results are also provided to demonstrate the accuracy of the analytical expressions.