In this paper, we consider a cooperative device-todevice (D2D) communication system, where the D2D transmitters (DTs) act as relays to assist the densified cellular network users (CUs) for transmission quality of service (QoS) improvement. The proposed system achieves a win-win situation, i.e. improving the spectrum efficiency of the CUs that cannot meet their rate requirement while providing spectrum access for D2D pairs. Unlike previous works, to reduce the overhead, we design a novel two-timescale resource allocation scheme, in which the pairing between CUs and D2D pairs is decided at a long timescale and transmission time for CU and D2D pair is determined at a short timescale. Specifically, to characterize the long-term payoff of each potential CU-D2D pair, we investigate the optimal cooperation policy to decide the transmission time based on the instantaneous channel state information (CSI). We prove that the optimal policy is a threshold policy which can be achieved via binary search. Since CUs and D2D pairs are self-interested, they are paired only when they agree to cooperate mutually. Therefore, to study the cooperation behaviors of CUs and D2D pairs, we formulate the pairing problem as a matching game, based on the long-term payoff achieved by the optimal cooperation policy of each possible pairing. Furthermore, unlike most previous matching models in D2D networks, we allow transfer between CUs and D2D pairs to improve the performance. To solve the pairing problem, a distributed algorithm is proposed, which converges to an \epsilon-stable matching. We show that there is a tradeoff between the optimality and the computational complexity of the algorithm. We also analyze the algorithm in terms of the robustness to the unilateral deviation of D2D pairs. Finally, the simulation results verify the efficiency of the proposed matching algorithm.

中文翻译：

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协作 D2D 通信的两个时间尺度资源分配：匹配博弈方法

在本文中，我们考虑了一种协作式设备到设备 (D2D) 通信系统，其中 D2D 发射机 (DT) 充当中继以帮助密集的蜂窝网络用户 (CU) 提高传输服务质量 (QoS)。所提出的系统实现了双赢的局面，即在为D2D对提供频谱接入的同时提高不能满足其速率要求的CU的频谱效率。与之前的工作不同，为了减少开销，我们设计了一种新的双时间尺度资源分配方案，其中 CU 和 D2D 对之间的配对在较长的时间尺度上确定，CU 和 D2D 对的传输时间在较短的时间尺度上确定。具体来说，为了表征每个潜在 CU-D2D 对的长期收益，我们研究了基于瞬时信道状态信息（CSI）来决定传输时间的最佳合作策略。我们证明了最优策略是一个可以通过二分搜索实现的阈值策略。由于 CU 和 D2D 对是自利的，只有当它们同意相互合作时才会配对。因此，为了研究 CU 和 D2D 对的合作行为，我们将配对问题制定为匹配博弈，基于每个可能配对的最优合作策略实现的长期收益。此外，与 D2D 网络中大多数以前的匹配模型不同，我们允许在 CU 和 D2D 对之间进行传输以提高性能。为了解决配对问题，提出了一种分布式算法，该算法收敛到一个\epsilon-stable 匹配。我们表明，在算法的最优性和计算复杂性之间存在权衡。我们还分析了算法对 D2D 对单边偏差的鲁棒性。最后，仿真结果验证了所提出的匹配算法的有效性。