无人机通信系统的物理层安全通信技术研究

Since the communication between UAV and legitimate users on the ground is easily wiretapped by an eavesdropper, resulting in information leakage and seriously affecting the security performance of the UAV communication system, this project studies the communication technologies of physical layer security for the UAV communication system. Firstly, by analyzing the characteristics of the UAV communication channel in multiple scenarios, the channel model in multiple scenarios is studied. Next, the mathematical representation of the secrecy outage probability for multiple scenarios is derived, then the impact of the channel parameters of UAV on the secure communication is explored, especially for the case that the UAV cannot obtain the exact information of the eavesdropper’s location. Secondly, based on the analysis of channel characteristics in multiple scenarios, the mechanism of multi-user access in UAV communication system is studied. Non-orthogonal multiple access and Han-Kobayashi scheme are mainly used, and their secrecy outage probabilities are analyzed. Finally, with the regard to the optimization for secrecy rate and energy efficiency, the sub-problems are obtained by decoupling multivariable with the alternating optimization approach, and then the relaxation condition is used to approximate the secrecy rate and energy efficiency function. For the optimization of flight trajectory and speed, the Markov decision process is established, combined with dynamic programming and reinforcement learning solution. Based on this, a low complexity fast convergence algorithm for optimizing transmit power is designed.

由于无人机和地面合法用户的通信容易被非法节点窃听，导致信息泄露，严重影响无人机通信系统的安全性能，本项目针对无人机通信系统，研究其物理层安全通信技术。首先，通过分析多场景下无人机通信信道的特点，研究多场景下的信道模型。接着，针对多场景的情况建立安全中断概率的数学表示，以此探索信道的参数对安全通信的影响，尤其是针对无人机无法掌握非法监听者准确位置信息的情况。其次，基于多场景下信道特征的分析，研究无人机通信系统中多用户接入的机制，主要采用非正交多址接入和Han-Kobayashi机制，并分析它们的安全中断概率。最后，对于安全速率和能效的优化，采用交替优化方法对多变量解耦获得子优化问题，进一步采用松弛条件将安全速率和能效函数等价转化。对于飞行轨迹和速度的优化，建立马尔可夫决策过程，结合动态规划和强化学习求解，在此基础上设计优化发射功率的低复杂度快速收敛算法。

无人机可以满足下一代通信网络的高覆盖、低延时等通信需求，但是无线信道的广播特性所带来的信息安全问题，成为无人机通信系统应用的关键因素之一。本项目旨在研究无人机通信系统的物理层安全技术，针对多场景下的无人机通信系统，探索影响无人机通信系统的物理层安全通信的机理，从利用无人机的飞行轨迹、发射功率控制、时频资源的调度等出发，研究多用户接入和配对机制，发展安全速率和能效优化的低复杂度快速收敛算法，为无人机通信系统的可靠性和稳定性提供理论基础和方法支撑。具体研究内容有：一、研究了多场景下的无人机通信系统的物理层安全通信，提出了适用于多场景的Han-Kobayashi多用户接入机制，研究了协作强窃听信道下的安全通信技术；二、研究了无人机辅助的双向中继多用户通信方案，考虑了无人机中继的四种工作模式；三、研究了强窃听信道下的多用户干扰网络物理层安全技术，探索了基于超可靠低时延通信(URLLC)的多用户干扰网络物理层安全传输方案。