Power Allocation for UAV Swarm-Enabled Secure Networks Using Large-Scale CSI

Unmanned aerial vehicle (UAV) swarm-enabled aerial network has emerged as an effective solution to ondemand communications, especially in unexpected scenarios. Due to the broadcast nature of the air-to-ground link, UAV swarm-enabled wireless communications are inherently prone to eavesdropping. The paper investigates power allocation for UAV swarm-enabled secure networks. To depict air-to-ground link, a composite channel consisting of small-scale and large-scale fading is taken into account. Because of the difficulty in acquiring the time-varying small-scale fading, we use the large-scale channel state information (CSI). An optimization framework in a whole- trajectory-oriented manner is proposed to maximize secrecy throughput with the constraints on the transmission power and the transmission durations as well as the overall transmission energy per UAV over a given flight period. The formulated problem is not convex. To deal with that, we first derive a closed form of secrecy throughput in the form of high-order fixed-point equations. Then, we propose an iterative algorithm with successive convex approximation technique by alternately optimizing the variables. Numerical results validate the effectiveness of the proposed scheme and show that our proposed scheme can achieve a good secrecy performance.