AbstractWe consider a wireless network consisting of multiple sources communicating with their corresponding destinations utilizing a single half-duplex relay. The goal is to minimize the outage probability of the total rate in the network by allocating transmission powers and durations as well as rates to the nodes based on instantaneous channel gains, while satisfying a total average network power. The sources are allowed to use the relay opportunistically, that is only when relaying reduces overall power as opposed to direct transmission. We investigate the effect of interference when all sources transmit simultaneously, and the impact of time division among the sources.We show that dynamic allocation and opportunistic transmission based on instantaneous channel states provide signi cant reduction in outage compared to any constant resource allocation scheme.