In this paper, we investigate the successful content delivery (SCD) performance in the unmanned aerial vehicle (UAV) integrated terrestrial cellular networks, where the caching-enabled UAVs are dispatched to offload the burst traffic from the cellular networks. Specifically, the UAV and terrestrial cellular network share the same spectrum resources for user downlink communications and each UAV uses millimeter wave (mmWave) communications for self-backhaul. We derive a closed-form expression of the achievable rate of the mmWave wireless backhaul link and then analyze the minimum cache hit probability to achieve a certain backhaul rate requirement. By approximating the general probabilistic line-of-sight (LoS) propagation model as a LoS ball model, we analyze the conditional SCD probabilities by leveraging stochastic geometry tools. Simulation results demonstrate that the UAV integrated cellular network can not only provide more access opportunities but also achieve higher SCD performance than the conventional terrestrial network for ground users. Moreover, there exists an optimal UAV density and height to maximize the SCD performance. Our results provide useful guidelines for the design and deployment of future UAV-assisted networks.

中文翻译：

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具有空中缓存和毫米波回程的蜂窝网络中的内容交付分析

在本文中，我们研究了无人驾驶飞行器 (UAV) 集成地面蜂窝网络中的成功内容交付 (SCD) 性能，其中调度启用缓存的 UAV 以从蜂窝网络卸载突发流量。具体来说，无人机和地面蜂窝网络共享相同的频谱资源用于用户下行通信，每个无人机都使用毫米波（mmWave）通信进行自回程。我们推导出毫米波无线回程链路可实现速率的闭式表达式，然后分析实现特定回程速率要求的最小缓存命中概率。通过将一般概率视线 (LoS) 传播模型近似为 LoS 球模型，我们利用随机几何工具分析了条件 SCD 概率。仿真结果表明，无人机综合蜂窝网络不仅可以为地面用户提供更多的接入机会，而且可以实现比传统地面网络更高的SCD性能。此外，存在最佳无人机密度和高度以最大化 SCD 性能。我们的结果为未来无人机辅助网络的设计和部署提供了有用的指导。