Distributed Opportunistic Scheduling in Cooperative Networks With RF Energy Harvesting

In this paper, the problem of distributed opportunistic channel access in wireless cooperative networks is investigated. To cope with the energy limitation problem of relay nodes, radio-frequency (RF) energy harvesting is considered, and thus, no external energy is needed for each relay node. Then, a novel distributed opportunistic scheduling (DOS) scheme is proposed. In the scheme, users contend for the channel access opportunity by random access, and then, the user with a successful contention makes a decision whether to give up the opportunity after probing the source-to-relay link and relay-to-destination link by following a strategy. To maximize the average throughput of the network, the optimal strategy of the proposed scheme, which is to help the user to decide whether to give up the transmission opportunity, is derived by optimal stopping theory. The obtained optimal strategy has a threshold-based structure, and thus, it is easy to implement in practice. In addition, the threshold can be calculated off-line by a proposed low-complexity algorithm. Simulation results are provided to demonstrate the superior performance of the proposed DOS scheme.