Secure probabilistic caching in random multi-user multi-UAV relay networks

Abstract

In this paper, we investigate the system model of random multi-user multi-UAV relay networks, where the transmission can be overheard by multiple eavesdroppers. We consider the random networks where the users, UAV relays and eavesdroppers arrive at the network subject to the homogeneous Poisson Point Process (PPP). Cache is equipped at UAV relays and users, and can pre-storage part of contents, which can help reduce the information leakage. Hence, it is of vital importance to design an effective secure probabilistic caching strategy to ensure the security of content transmission by combining the cache strategy and the physical-layer security in the presence of eavesdroppers. To this end, we first design the caching placement at users and UAV relays by taking into account four transmission schemes. We then analyze the secure performance of the caching placement by analyzing the expression of secure cache throughput. To maximize the secure cache throughput, we further optimize the probabilistic caching strategy by using the heuristic algorithm. Numerical results and discussion are provided to demonstrate that the proposed probabilistic caching strategy outperforms the conventional most popular content (MPC) and equal probability content (EPC) cache strategies, and the system secure performance can be improved by increasing the cache size and the intensity of UAV relays and users.