Performance Analysis and Caching Design in Fog Radio Access Networks

In this paper, the edge caching problem in fog radio access networks (F-RAN) is investigated. Considering that fog access points (F-APs) can offer cooperation gain by jointly transmitting the same file or content diversity gain by concurrently transmitting the coded subfiles, we propose to use both joint transmission (JT) strategy and parallel transmission (PT) strategy to serve users. Using stochastic geometry, we first derive the successful transmission probability (STP) with different transmission strategies, and further derive the fractional offloaded traffic (FOT). Finally, the optimal caching design is obtained by maximizing the STP and FOT. Simulation results show that our proposed caching design achieves a significant performance gain in comparison with the baselines.