Access Points Cooperation Based Secretive Coded Caching in Fog Radio Access Networks

In this study, we address the issue of secretive coded caching in fog radio access networks (F-RANs). Our approach involves a hierarchical placement scheme during the placement phase, which efficiently leverages the cache resources of both fog access points (F-APs) and users while adhering to secrecy constraints. In the delivery phase, we employ an access points cooperation based delivery scheme that maximizes the cooperative transmission capability among multiple F-APs. By integrating the placement and delivery schemes, we propose an access points cooperation based secretive coded caching scheme that minimize the sum rate. We further derive a closed-form expression for the worst-case sum rate and obtain an information theretic lower bound on the sum rate by using cut-set arguments. Our analysis reveals that the proposed scheme achieves the information theoretic lower bound within a factor that depends on the number of F-APs. Additionally, we analyze the decodability and secrecy aspects of the proposed coded caching scheme. Simulation results demonstrate that when the cache capacity of each F-AP is large, the performance of our proposed scheme approaches the theoretical optimum.