Federated Learning-Based Content Popularity Prediction in Fog Radio Access Networks

In this paper the content popularity prediction problem in fog radio access networks (F-RANs) is investigated. In order to obtain accurate prediction with low complexity we propose a novel context-aware popularity prediction policy based on federated learning (FL). Firstly user preference learning is applied by considering that users prefer to request the contents they are interested in. Then users’ context information is utilized to cluster users efficiently by adaptive context space partitioning. After that we formulate a popularity prediction optimization problem to learn the local model parameters by using the stochastic variance reduced gradient (SVRG) algorithm. Finally FL based model integration is proposed to learn the global popularity prediction model based on local models using the distributed approximate Newton (DANE) algorithm with SVRG. Our proposed popularity prediction policy not only can predict content popularity accurately but also can significantly reduce computational complexity. Moreover we theoretically analyze the convergence bound of our proposed FL based model integration algorithm. Simulation results show that our proposed policy increases the cache hit rate by up to 21.5 % compared to existing policies.