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.

中文翻译：

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带有射频能量收集的协作网络中的分布式机会调度

本文研究了无线合作网络中的分布式机会信道访问问题。为了解决中继节点的能量限制问题，考虑了射频（RF）能量收集，因此，不需要每个中继节点的外部能量。然后，提出了一种新颖的分布式机会调度（DOS）方案。在该方案中，用户通过随机访问来竞争信道访问机会，然后，竞争成功的用户通过探测源到中继链路和中继到目的地链路，来决定是否放弃该机会。遵循策略。为了使网络的平均吞吐量最大化，所提出方案的最佳策略是帮助用户决定是否放弃传输机会，由最佳停止理论得出。所获得的最优策略具有基于阈值的结构，因此在实践中易于实现。另外，阈值可以通过提出的低复杂度算法离线计算。仿真结果表明了所提出的DOS方案的优越性能。