无人机中继链路传播损耗及性能分析

针对两跳无人机中继通信场景，综合考虑机身姿态、天线特性、气候状况及信道衰落等影响，建立了两跳中继链路的传播损耗模型，分析了传播损耗均值的计算方法，推导了多径阴影复合衰落导致传播损耗随机起伏的统计特性。在此基础上，进一步推导得到了两跳无人机中继系统的中断概率与误比特率的理论表达式。最后，通过对郊区、山区和海洋场景的数值仿真，验证了本文推导的理论结果的正确性，并分析了无人机飞行高度、地面节点位置以及通信场景等因素对两跳中继系统性能的影响。

Propagation Loss and Performance Evaluation of UAV Relay Link

For the dual-hop relay system of unmanned aerial vehicle (UAV), a propagation loss model of dual-hop relay link is established. The influence of fuselage feature, antenna characteristics, climate condition and channel fading are considered. Based on the model, the calculating methods of propagation loss are analyzed. Then the statistical characteristics of propagation loss with random fluctuation caused by composite fading including shadowing and multipath fading are derived. Furthermore, the theoretical expression of the outage probability and bit error rate (BER) of dual-hop UAV relay system is developed. Finally, through the numerical simulations in urban, mountainous and sea, the theoretical results accuracy obtained is verified and the impact of flight altitude, ground node position and communication scenarios on the performance of the dual-hop relay system is discussed.