Optimal Wireless Streaming of Multi-Quality 360 VR Video By Exploiting Natural, Relative Smoothness-Enabled, and Transcoding-Enabled Multicast Opportunities

In this paper, we would like to investigate the optimal wireless streaming of a multi-quality tiled 360 virtual reality (VR) video from server multiple users. To end, propose maximally exploit potential multicast opportunities by effectively utilizing characteristics VR videos and computation resources at users' side. particular, consider two requirements for quality variation in one field-of-view (FoV), i.e., absolute smoothness requirement relative requirement, playback modes, direct-playback mode (without user transcoding) transcode-playback (with transcoding). Besides natural opportunities, introduce new types namely, smoothness-enabled which allow flexible tradeoff between viewing communications resource consumption, transcoding-enabled consumptions. Then, establish novel mathematical model that reflects impacts natural, smoothness-enabled, on average transmission energy transcoding energy. Based model, optimize allocation, level selection, selection minimize consumption four cases with different modes. By comparing values cases, prove reduces when more can be utilized. Finally, numerical results show substantial gains proposed solutions over existing schemes, demonstrate importance exploiting three opportunities.