Single Relay Selection Schemes for Broadcast Networks

Achieving the goal of reliably delivering data to all nodes in broadcast wireless networks is very challenging since wireless channels may experience severe variations in signal strength and channel impairments. To mitigate this problem, one or several relays can be used as collaborators to forward the broadcasted signal to other nodes. In this paper, we propose and investigate several single relay selection schemes in broadcast wireless networks using either selective digital relaying or selective analog relaying. The key idea is to classify the nodes in the considered broadcast network into two sets. A set of "reliable" nodes, whose source-node signal-to-noise ratio exceeds a threshold value and a set of "unreliable" nodes gathering the remaining ones. Then, one node among "reliable" nodes is activated as a relay. We derive closed form expressions of the end-to-end bit error probabilities of some proposed single relay selection schemes for selective digital relaying. The data rate loss due to the cooperation is also studied. Analytical results along with simulations prove that compared to the direct transmission, the single relay selection schemes improve significantly the bit error probability performance of the broadcast network.