TranscodingEnabled Edge Caching and Delivery for TileBased Adaptive 360Degree Video Streaming The highdefinition and panorama characteristics of 360degree video make its transmission in existing networks more challenging. To alleviate this problem, this paper leverages transcodingenabled edge caching in tilegranularity and makes joint caching, transcoding and delivery decisions among multiple edge servers for adaptive 360degree video streaming. We formulate the joint caching, transcoding and delivery decisionmaking problem as a multivariate nonlinear integer programming problem, aiming at minimizing the aggregate network operational cost and balancing the server load, subject to storage and computation capacity constraints of the edge servers. Through decomposition and relaxation approach, the original intractable optimization problem is solved by an effective iterative algorithm. Finally, simulation results show that the proposed iterative algorithm outperforms the existing schemes in terms of resource utilization, cost reduction and server coordination.

A Hierarchical Update Buffer Management for 360Degree Video Streaming Virtual reality can provide users with immersive experience. However, because of its high requirement of bandwidth, it is still challenge to transmit 360degree video. To overcome this issue, tilebased VR transmission strategy was proposed to reduce the data by dividing the 360degree video into several tiles and streaming corresponding tiles according to userxe2x80x99s viewport. While the prediction accuracy is only guaranteed in a short time and it may cause frequent rebuffering when the network fluctuates, twotier buffer system was proposed to tackle this problem. Nevertheless the twotier method doesnxe2x80x99t consider the switching frequency of rate in userxe2x80x99s viewport. In this paper, we propose a novel hierarchical update buffer management method by jointly considering the probability of rebuffering and the switching frequency of rate in FoV to improve userxe2x80x99s QoE. The simulation results show that our proposed algorithm outperforms other methods in proving the smoothness of the viewing experience.