Currently, VR video delivery over 5G systems is still a very complicated endeavor. One of the major challenges for VR video streaming is the expectations for low latency that current mobile networks can hardly meet. Network caching can reduce the content delivery latency efficiently. However, current caching schemes cannot obtain ideal results for VR video since it requests the viewport interactively. In this paper, we propose a tiled scalable VR video caching scheme over 5G networks. VR chunks are first encoded into multi-granularity quality layers, and are then partitioned into tiles to facilitate viewport data access. By accommodating the 5G network infrastructure, the tiles are cooperatively cached in a three-level hierarchal system to reduce delivery latency. Furthermore, a quality-adaptive request routing algorithm is designed to cater for the 5G bandwidth dynamics. Experimental results show that the proposed scheme can reduce the transmission latency over conventional constant bitrate video caching schemes.

目前，通过 5G 系统传输 VR 视频仍然是一项非常复杂的工作。VR 视频流的主要挑战之一是当前移动网络难以满足的低延迟期望。网络缓存可以有效地减少内容交付延迟。然而，当前的缓存方案无法为 VR 视频获得理想的结果，因为它以交互方式请求视口。在本文中，我们提出了一种基于 5G 网络的平铺可扩展 VR 视频缓存方案。VR 块首先被编码成多粒度质量层，然后被分割成瓦片以方便视口数据访问。通过适应 5G 网络基础设施，瓦片被协同缓存在一个三级分层系统中，以减少交付延迟。此外，质量自适应请求路由算法旨在满足 5G 带宽动态。实验结果表明，与传统的恒定比特率视频缓存方案相比，所提出的方案可以减少传输延迟。