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arXiv 1902.07418cs.NImath.OC
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无线信道上视频流的最优分散动态策略

Optimal Decentralized Dynamic Policies for Video Streaming over Wireless Channels

Rahul Singh, P. R. Kumar

摘要:

解决的问题是以分散的方式最佳地控制移动视频的下载,预计到2020年,移动视频将占移动数据流量的75%。服务器可以从以不同分辨率对其视频进行编码的多个数据包中动态选择要下载到客户端的数据包,以及它们传输的功率电平。这使其能够控制数据包传输概率,从而避免客户端即将发生的视频中断。然而,它必须尊重接入点对带宽和平均传输功率的限制。目标是最大化视频“体验质量”(QoE),这取决于若干因素,例如(i)当视频回放缓冲器为空时的中断持续时间,(ii)中断周期的数量,(iii)下载的帧有多少是较低分辨率的,(iv)分辨率的时间变化等。并且每个客户端分布式地并且动态地最大化其自身的QoE,这取决于能量成本。最后给出了求解最优分散策略的分布式迭代算法。此外,对于客户端级别的QoE优化,视频分辨率和分组传输的功率级别的最佳选择相对于视频回放缓冲器级别具有简单的单调性和阈值结构。当正交信道的数量小于客户端的数量时,存在用于优先化分组传输的索引策略。当AP必须简单地选择传输哪些客户端的数据包时,索引策略是渐进最优的,因为信道的数量随着客户端而按比例增加。

英文摘要:

The problem addressed is that of optimally controlling, in a decentralized fashion, the download of mobile video, which is expected to comprise 75 % of total mobile data traffic by 2020. The server can dynamically choose which packets to download to clients, from among several packets which encode their videos at different resolutions, as well as the power levels of their transmissions. This allows it to control packet delivery probabilities, and thereby, for example, avert imminent video outages at clients. It must however respect the access point's constraints on bandwidth and average transmission power. The goal is to maximize video "Quality of Experience" (QoE), which depends on several factors such as (i) outage duration when the video playback buffer is empty, (ii) number of outage periods, (iii) how many frames downloaded are of lower resolution, (iv) temporal variations in resolution, etc. It is shown that there exists an optimal decentralized solution where the AP announces the price of energy, and each client distributedly and dynamically maximizes its own QoE subject to the cost of energy. A distributed iterative algorithm to solve for optimal decentralized policy is also presented. Further, for the client-level QoE optimization, the optimal choice of video-resolution and power-level of packet transmissions has a simple monotonicity and threshold structure vis-a-vis video playback buffer level. When the number of orthogonal channels is less than the number of clients, there is an index policy for prioritizing packet transmissions. When the AP has to simply choose which clients' packets to transmit, the index policy is asymptotically optimal as the number of channels is scaled up with clients.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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