Hybrid Cache Placement for Improving Physical Layer Security in Cooperative Networks

Employing traditional wireless two-hop relaying is very easy for eavesdropper to overhear message due to the broadcasting nature of transmission. However, relays, which are equipped with caching capabilities to store popular content, can serve the destination directly without fetching messages from source. In order to improve physical layer security, the design of hybrid cache placement becomes more and more critical. In this paper, we consider a cooperation network with caching relays and propose a novel method that by utilizing hybrid cache placement to improve the physical layer security. Based on the proposed method, the function of secrecy outage probability and average secrecy capacity are derived to optimize the hybrid cache placement. And the numerical and simulation results also demonstrate the proposed method outperforms the traditional transmission without caching.