Energy-aware relay selection for multiuser relay networks

We consider a dual-hop relay network with multiple source-destination (S-D) pairs and multiple relays, where amplify-and-forward relaying strategy is applied and transmission among S-D pairs takes place simultaneously. Network lifetime in this scenario is defined as the time interval over which successful transmission of all S-D pairs through selected relays can be maintained. We aim at designing relay selection to maximize the network lifetime for given data rate requirements of all the S-D pairs. Without knowledge of future channel states, we design relay selection algorithms to maximize perceived network lifetime at the current time. The perceived network lifetime maximization is shown to be a max-min optimization problem. We propose a priority search algorithm which is shown to provide the optimal solution with linear complexity in the number of relays. Furthermore, we propose a suboptimal priority-based selection strategy, the “worst-case” greedy algorithm, with complexity linear in the number of relays and quadratic in the number of S-D pairs. Simulation results show that the performance loss of the “worst-case” greedy algorithm is negligible as compared to the optimal relay selection solution.