One of the most attractive applications of unmanned aerial vehicles (UAVs) is deploying wireless communication systems. We consider a UAV-based low-altitude platform (LAP) to deploy an aerial hotspot to provide Wi-Fi coverage without infrastructure and severe shadowing by urban or mountainous terrain. To address the performance degradation of carrier sense multiple access with collision avoidance (CSMA/CA) by increasing packet collisions with the number of clients, we exploit nonorthogonal multiple access (NOMA). To the best of authors’ knowledge, there are no previous studies on uplink NOMA in CSMA/CA networks. In the considered system, owing to the distributed architecture and small channel difference of stations, conventional NOMA methods in cellular systems are not suitable. In this paper, we propose a power allocation scheme for uplink transmissions using predetermined power levels with a stochastic power selection to reduce the probability of packet collisions. A new medium access control procedure for uplink NOMA with CSMA/CA is also presented. The analytic results demonstrate that the proposed scheme achieves better saturation throughput and average packet delay than conventional CSMA/CA.

中文翻译：

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使用 UAV 辅助 CSMA/CA 网络的功率分配的上行链路 NOMA

无人驾驶飞行器 (UAV) 最具吸引力的应用之一是部署无线通信系统。我们考虑使用基于无人机的低空平台 (LAP) 来部署空中热点以提供 Wi-Fi 覆盖，而无需基础设施和城市或山区地形的严重阴影。为了通过增加与客户端数量的数据包冲突来解决带有冲突避免的载波侦听多路访问 (CSMA/CA) 的性能下降问题，我们利用了非正交多路访问 (NOMA)。据作者所知，以前没有关于 CSMA/CA 网络中上行链路 NOMA 的研究。在所考虑的系统中，由于站的分布式架构和小信道差异，蜂窝系统中的常规NOMA方法不适用。在本文中，我们提出了一种上行链路传输的功率分配方案，该方案使用具有随机功率选择的预定功率电平来降低数据包冲突的概率。还提出了具有 CSMA/CA 的上行链路 NOMA 的新媒体访问控制程序。分析结果表明，所提出的方案比传统的 CSMA/CA 实现了更好的饱和吞吐量和平均数据包延迟。