Energy Price-Based Resource Scheduling for Network Lifetime Extending in Cooperative D2D Communications Overlaying Cellular Networks

This paper considers device-to-device (D2D) communications overlaying cellular networks. Combined with cooperative relay technology, a D2D user can serve as a relay for a cellular link and gain the opportunity to access the corresponding cellular spectrum. Considering mobile terminals' limited battery capacity and motivated by green communication, we propose a resource scheduling scheme, which comprises joint power and spectrum allocation, mode selection, and link matching. Unlike previous works, to balance energy utilization and extend the network lifetime, this scheme sets a price for each node and minimizes the system cost during each frame instead of energy efficiency (EE). Specifically, we investigate the power and spectrum allocation problem to characterize the minimum cost of matched links. We prove it to be nonconvex and obtain the optimal solution by the graphic method and Newton's method with a small number of iterations. We also discuss the energy pricing strategy. In order to reduce communication and computation overhead, we propose a heuristic pricing strategy that involves no iteration and supposes nodes' energy prices are inversely proportional to their residual energy. Through simulations under various cases, we verify that the proposed scheme significantly improves network lifetime and suits real-time operations while guaranteeing the quality of service (QoS) requirement. Moreover, the simulation results demonstrate that the proposed scheme performs the same as the maximum EE scheme if the energy prices are equal at each node.