无人机对地通信系统具有部署灵活，不受地形环境影响等优点，能通过增加视距链路的概率提高空地通信信道质量，提升系统容量。在蜂窝网络中利用无人机进行大范围数据采集，网络增强覆盖能够有效降低基础设施投入，提升网络容量。但面临两方面难题，无人机留空时间受到能量限制，无人机如何通过自主寻迹最大化网络性能。本课题将探索无人机飞行能效和飞行路径优化两方面问题，重点研究以下三个内容1）分析无人机数据采集系统的飞行能耗与地面通信能耗的折中关系2）利用多无人机协同自主飞行路径优化策略，降低网内干扰，提升网络系统容量3）研究无人机辅助基站增强覆盖场景下边缘用户归属策略，通过优化无线资源分配，提高边缘用户传输速率。本研究有助于发掘无人机移动性给系统带来的性能增益，通过优化的飞行路径及飞行姿态，提升网络性能，降低无人机飞行能耗，增加留空时间。研究成果能突破传统陆基通信系统的限制，为5G网络增强覆盖提供解决方案。

Unmanned aerial vehicle (UAV)-to-ground communication systems has the advantages of flexible deployment, high-maneuverability and immune to terrain environment. Such communication systems can improve the communication quality of air to ground (A2G) link and enhance the system capacity by increasing the probability of line-of-sight link. Use of UAV as large-scale data collection and network coverage enhancement in the cellular network can effectively reduce infrastructure investment, enhance network capacity. However, UAV communication in cellular network scenarios represents major challenges from both the energy constraint when UAVs hovering and how to maximize network performance by autonomous planning trajectory perspectives. Our project will explore the two aspects of UAVs flight energy efficiency and trajectory optimization, focusing on the following three topics: (i) analyze the trade-off between communication energy consumption and flight energy consumption for UAVs data collection systems, (ii) applying the optimal trajectory to cooperative autonomous multiple-UAV system for reducing the inter-network interference and improving network system capacity, (iii) studying the edge user’s attribution strategy for UAV assisted base station coverage enhancement scenario, improve the transmission rate of the edge users by optimizing the allocation of wireless resources. This research will help us to explore the system performance gain created by UAV mobility, by optimizing the flight path and flight attitude, the network performance is improved, the energy consumption of UAV is reduced, and the blanking time is increased. Our research results can break through the limitations of traditional land-based communication systems and provide novel solutions for coverage enhancement of 5G networks.