概率视距空地信道下的无人机安全通信优化设计研究

UAV secure communication optimization design under probabilistic line-of-sight air-ground channels

考虑在物理层保障无人机多用户通信系统的信息传输安全,一架无人机与多个地面用户进行通信,存在一个地面窃听者尝试窃取无人机发送给用户的机密信息。研究将无人机与地面节点之间的空地信道建模为更符合实际的概率视距信道,在满足无人机飞行条件约束和离散的用户调度约束下,通过联合设计无人机的三维飞行轨迹和用户调度来最大化用户的最小平均安全速率。为求解该模型下的安全通信优化设计问题,首先将其解耦为三个子问题,然后利用整数松弛和连续凸近似方法分别求解三个子问题,最后利用块坐标下降法求出无人机的三维飞行轨迹;在此基础上,根据飞行过程中得到的瞬时信道状态信息,提出无人机飞行速度和用户调度实时优化算法。该算法将优化问题建模为线性规划问题,并用内点法求解。仿真结果表明,与已有基准算法相比,基于概率视距信道模型优化无人机的飞行轨迹可显著提升系统的安全速率,所提的飞行速度和用户调度实时优化算法可进一步提升安全速率性能。

This paper considered the physical-layer security of information transmission in an unmanned aerial vehicle(UAV)multi-user communication system,where a UAV communicated with multiple users on the ground,with the presence of an eavesdropper on the ground trying to intercept the confidential information sent from the UAV to the users.It modeled the channels between the UAV and all ground nodes as more accurate probabilistic LoS(line-of-sight)channels.This paper studied maximizing the minimum average secrecy rate of all users by jointly designing the 3D trajectory of the UAV and the user scheduling,under the constraints of UAV fight conditions and the discrete user scheduling parameters.To solve the optimization design problem for the UAV secure communication system under the probabilistic LoS channel model,this paper first decoupled it into three sub-problem,then solved the three sub-problems one by one,by using the integer relaxation and successive convex approximation methods,and finally obtained the 3D flight trajectory of UAV by using the block coordinate descent method.Based on the instantaneous channel state information obtained during the UAV’s flight,it further proposed a real-time optimization algorithm for UAV speed and user scheduling.This algorithm formulated the optimization problem into a linear programming problem and solved it by using the interior point method.Simulation results show that compared to the existing benchmark algorithms,the trajectory optimization of UAV based on the probabilistic LoS channel model can significantly improve the secrecy rate of the system,and the proposed real-time optimization algorithm for speed and user scheduling can further improve the secrecy rate performance.