Power Allocation and Relay Selection in Dual-Hop Regenerative Relaying Systems

In this paper, we consider a relay system with a number of potential relay nodes. We propose several relay assignment protocols to select a relay node to help transmit source data so that the average outage probability of the system is reduced. These protocols include: Optimal-Position relay assignment, Nearest-Optimal-Position relay assignment, and Left (Right)Nearest-Optimal-Position relay assignment, all of which will be compared with the existing Nearest-Neighbor relay assignment protocol in literature. Further more, we provide adaptive power allocation (PA) at the source node and the assigned relay node under a joint transmit power constraint. Simulation results show that Optimal-Position relay assignment (ideal case) and Nearest-Optimal-Position relay assignment (practical case) with adaptive PA significantly outperform other relay assignment protocols as well as the direct transmission.