Joint EPC and RAN Caching of Tiled VR Videos for Mobile Networks

In recent years, 360-degree VR (Virtual Reality) video has brought an immersive way to consume content. People can watch matches, play games and view movies by wearing VR headsets. To provide such online VR video services anywhere and anytime, the VR videos need to be delivered over wireless networks. However, due to the huge data volume and the frequent viewport-updating of VR video, its delivery over mobile networks is extremely difficult. One of the difficulties for the VR video streaming is the latency issue, i.e., the necessary viewport data cannot be timely updated to keep pace with the rapid viewport motion during viewing VR videos. To deal with this problem, this paper presents a joint EPC (Evolved Packet Core) and RAN (Radio Access Network) tile-caching scheme that pushes the duplicates of VR video tiles near the user end. Based on the predicted viewport-popularity of the VR video, the collaborative tile data caching between the EPC and RAN is formulated as a 0-1 knapsack problem, and then solved by a genetic algorithm (GA). Experimental results show that the proposed scheme can achieve great improvements in terms of the saved transmission bandwidth as well as the latency over the scheme of traditional full-size video caching and the scheme that the tiles are only cached in the EPC.