【作者】 王芳；

【导师】 黄韬；

【作者基本信息】 北京邮电大学 ， 电子与通信工程， 2018， 硕士

【摘要】 随着手机等移动终端的飞速发展,移动互联网所承载的数据量急剧增长。在移动网络所传输的内容中,视频内容占据了的很大的比例,并且这一比例还在逐年增长。然而,移动网络的普及以及视频直播等业务的发展,为人们的生活带来便利的同时,也为移动网络的内容分发带来了极大的挑战。现在很多企业广泛采用了内容分发网络(CDN,Content Delivery Network),但是移动网络下的内容分发技术还存在许多瓶颈。为解决这些瓶颈,移动网络运营商尝试在现有架构中部署移动内容分发网络(Mobile Content Delivery Network,MCDN)。本文首先分析了 CDN技术基础、流媒体传输关键技术,并围绕着移动网络中缓存及内容分发技术进行了研究。在理论基础的研究上,还进行了相关实践,设计并实现了移动网络内容分发系统。文章还提出将移动边缘计算节点(Mobile Edge Computing,MEC)作为缓存节点,采用多级缓存等方式,实现无线侧的内容缓存。同时提出协同区域的概念,通过缓存节点间的协同,提高协同区域内节点的缓存利用率,并将所开发的内容分发系统作为测试平台,进行了相关策略的验证。此外,本文通过对Ali-Nieson、PDA、时延敏感型等几种编码缓存算法的研究,提出了应用于流媒体视频,考虑业务优先级的场景优化策略。并通过本文所开发的平台将该策略进行了测试验证。系统的开发使用了很多新技术,运用了模块化的思想。并且文中对各个模块,技术框架、部署等进行了详细的设计。其中播放器模块的实现参考了基于HTTP的自适应流(Http Live Streaming,HLS)协议,将m3u8列表的生成从服务端迁移到了客户端,使整个传输网络可以忽略在移动分发网络中视频自适应传输的复杂性。虽然该平台已经能够灵活稳定的实现多种缓存策略,但是,在安全性、性能优化等方面仍然存在许多需要改进之处,这些改进工作也将成为日后研究的重点。更多还原

【Abstract】 With the rapid development of intelligent mobile terminals such as mobile phones,the data carried by mobile network is growing rapidly.Video transmission occupies a large proportion of the content of the mobile network transmission,and this proportion is increasing year by year with a rapid trend.The popularity of mobile network,intelligent mobile terminals,live video and other services has brings much convenience and efficiency to people,but also great challenges for content delivery of mobile network.Nowadays,CDN(Content Delivery Network)is widely used by some companies,but there are also many bottlenecks in content distribution technology for mobile networks.To solve these problems,mobile network operators try to deploy mobile content delivery network(mobile CDN)in existing architectures.In this paper,we first analyze the foundation of CDN technology,the key technology of streaming media transmission in wireless environment,and focus on the caching and content delivery technology in mobile network.On the basis of theoretical research,a series of practices has been carried out,in which we designed and implemented the MCDN system.In this paper,MEC is used as cache,and hierarchical caching is used to implement content caching on the wireless side.At the same time,the concept of collaborative region is proposed to improve the cache utilization of collaborative regional nodes through the cooperation of cache nodes.what’s more,the developed system is used as a test platform to verify the strategy.In addition,through the research of Ali-Nieson,PDA,delay sensitive encoding caching algorithm,an optimization algorithm based on streaming media is proposed,which has considered service priority.The strategy is also tested and verified by the platform developed in this paper.The development of the system uses a lot of new technology,and the system is divided into several parts based on the idea of modularization.This paper has described the various modules,technical framework,deployment,etc.in detail.The design of video player has referenced HLS protocol.The m3u8 list is formed from the server migration to the client,so that the whole network can ignore the complexity of adaptive media transmission.Although the implementation of the platform has been able to achieve a variety of caching strategies,but there are still many areas in need of improvement,such as in security,performance optimization,etc.These improvements will also become the focus in the future.更多还原