【作者】 倪纯豪；

【导师】 黄本雄；

【作者基本信息】 华中科技大学 ， 通信与信息系统， 2007， 硕士

【摘要】 随着宽带网络技术和流媒体技术的不断成熟和发展,网络电视(IPTV, Internet Protocol Television)技术正在走进千家万户。IPTV不仅能使普通家庭用户可以随时使用他们最熟悉的电视机根据各人喜好有选择地观看互联网上丰富的电影、电视剧、文艺节目、新闻等娱乐和资讯内容,而且使远程教育和在线培训的实施和普及更加方便快捷。在IPTV业务中,使用内容分发网(CDN, Content Delivery Network)能有效提高IPTV的网络服务质量(Qos)。通过CDN把视频内容分发到靠近用户端的边缘节点,利用边缘节点为用户提供服务,很好地解决了用户访问量大和服务器分布不均对骨干网造成的拥塞问题,可以在一定程度上保证端到端的服务质量,减轻IPTV业务对骨干网络的冲击,提高用户的响应速度。重点研究了IPTV所涉及的两个关键技术:内容分发技术和负载均衡技术。首先从CDN的基本概念入手,阐述了CDN网络的原理,并给出了适合IPTV的CDN网络架构。并依据IPTV的特点对分发存储技术进行了分析研究,给出了适合于IPTV系统的内容分发技术,即基于定长分段的内容分发机制。该分段下发机制先将节目分成大小相同的若干段,并对每段编号,再将节目片段推到下层存储服务器,从而实现分段下发的分发机制。负载均衡也是IPTV系统中的重点和难点,直接影响到系统的用户服务能力,先分析了服务器负载均衡的技术和常见实现策略,接着给出了基于分段机制的负载均衡方法,并对分段长度对系统负载均衡效果的影响进行了测试分析。该方法在考虑了大量用户请求的调度问题的同时还根据用户访问的特点,对大量视频文件进行了合理的分配,提高了服务质量。从商用情况来看,系统能够满足服务质量和服务能力的要求,性能稳定,具有较高的性价比。更多还原

【Abstract】 With the development of broad band network and streaming media technology, IPTV (Internet Protocol Television) has entered to general families. IPTV technique not only enables regular users to choose their favorite information and content, such as movies, TV series, entertainment programs and news with well-known TV sets at anytime, but also makes remote education and online training more convenient and efficient.CDN technology can enhance the Quality of Service (QoS) in IPTV system. With the help of CDN, IPTV can distribute the contents to much closer places to users. This will get rid of the congestion brought in by the large number of users, and thus reduce the pressure brought in by IPTV to the Internet, and shorten the response time to users.It emphatically studies two key technologies in IPTV system: content distribution and load balance. It introduces the conception and theory of Content Delivery Network, expatiates the rationale of CDN, and gives the framework suitable for IPTV. Meanwhile it analyses the strategy which is based on equally segmented distributed policy. The strategy divides the program into equal segments and number them, then push the segments to ME to realize the media segmented distributed technique which is quite suitable for IPTV system.Load balance is the key point and difficulty in IPTV system, affecting directly the system user’s service ability. Therefore, it gives a load balance method which is based on segmented distributed policy after it introduces the technology and common realized strategies of load balance, meanwhile test the influence of segment scale to system load balance. This strategy includes the following algorithms: Media server selection algorithms, which is to assign user request; File balance algorithms, which is to adjust file distribution based on requesting rate.The application result indicates that the system can meet requirement not only the service quality but also service ability. It runs stably, and the cost performance is fairly high.更多还原