Wireless Multicast of Virtual Reality Videos With MPEG-I Format

Deploying virtual reality (VR) streaming systems over wireless networks can provide an immersive environment for users without behavioral restrictions, and thus has drawn considerable attentions recently. MPEG-I as a new panorama video standard just targets such immersive multimedia applications. Although multiple VR delivery schemes have been proposed, MPEG-I has not been sufficiently researched, especially for multicast scenarios. Therefore, in this paper, we would like to design a multicast scheme to deliver 360 VR videos with MPEG-I format. Specifically, based on the prediction of users' viewports, we formulate an optimization problem of user grouping and bandwidth allocation to maximize user utilities. To solve the problem, we first propose a method which is composed of an optimal bandwidth allocation algorithm and a two-level hierarchical user grouping scheme. Furthermore, we consider the channel feedback overhead in multicast scenarios with a large number of users. Based on a reasonable assumption, we propose a simplified grouping method with low feedback overhead. Simulation results demonstrate the effectiveness of our proposed method, which yields similar performance compared to an exhausting search method when serving a large number of users with high SNRs.