Air-to-ground (A2G) networks, using unmanned aerial vehicles (UAVs) as base stations to serve terrestrial user equipments (UEs), are promising for extending the spatial coverage capability in future communication systems. Coordinated transmission among multiple UAVs significantly improves network coverage and throughput compared to a single UAV transmission. However, implementing coordinated multi-point (CoMP) transmission for UAV mobility requires complex cooperation procedures, regardless of the handoff mechanism involved. This paper designs a novel CoMP transmission strategy that enables terrestrial UEs to achieve reliable and seamless connections with mobile UAVs. Specifically, a computationally efficient CoMP transmission method based on the theory of Poisson-Delaunay triangulation is developed, where an efficient subdivision search strategy for a CoMP UAV set is designed to minimize search overhead by a divide-and-conquer approach. For concrete performance evaluation, the cooperative handoff probability of the typical UE is analyzed, and the coverage probability with handoffs is derived. Simulation results demonstrate that the proposed scheme outperforms the conventional Voronoi scheme with the nearest serving UAV regarding coverage probabilities with handoffs. Moreover, each UE has a fixed and unique serving UAV set to avoid real-time dynamic UAV searching and achieve effective load balancing, significantly reducing system resource costs and enhancing network coverage performance.

翻译：空地网络利用无人机作为基站为地面用户设备提供服务，有望在未来通信系统中扩展空间覆盖能力。与单无人机传输相比，多无人机间的协同传输能显著提升网络覆盖范围和吞吐量。然而，为实现无人机移动性而实施协调多点传输，无论涉及何种切换机制，都需要复杂的协作流程。本文设计了一种新颖的CoMP传输策略，使地面用户设备能够与移动无人机建立可靠且无缝的连接。具体而言，基于泊松-德劳内三角剖分理论，我们开发了一种计算高效的CoMP传输方法，其中设计了针对CoMP无人机集合的高效分区搜索策略，通过分治法最小化搜索开销。为进行具体性能评估，本文分析了典型用户的协作切换概率，并推导了包含切换过程的覆盖概率。仿真结果表明，在考虑切换的覆盖概率方面，所提方案优于采用最近服务无人机的传统Voronoi方案。此外，每个用户设备具有固定且唯一的服务无人机集合，避免了实时动态无人机搜索并实现了有效负载均衡，从而显著降低系统资源成本并提升网络覆盖性能。