【作者】 王征；

【导师】 陈纯； 张海翔；

【作者基本信息】 浙江大学 ， 计算机应用技术， 2006， 硕士

【摘要】 流媒体技术是当前网络应用领域中的研究热点,而流媒体技术与移动终端平台的结合,则促进了移动流媒体的发展。移动流媒体应刚遵循流媒体技术的一般要求,即实时性,平滑性和同步性。要实现这三个要求,需要开发性能优良的流媒体传输协议。 RTP协议是传输流媒体数据的主流传输协议。它介于传输层和应层层之间,通过UDP协议提高传输的实时性,并且在数据传输的同时,主动采集网络传输的状态信息,从而为上层应用提供了质量控制的手段。然而RTP协议本身并不处理这些信息,因此完整的传输框架需要增加质量保证机制,其中主要的部分就是拥塞控制。移动终端流媒体传输协议的拥塞控制机制不仅需要与RTP协议相结合,也需要与移动终端的性能特点相结合。通过分析与比较现有拥塞控制机制的原理与表现,针对性地提出一种移动终端自适应拥塞控制算法,使RTP协议的功能得到增强,并通过改进RTP控制协议的工作模式,增强了RTP协议的可扩展性。 由于目前通用RTP协议类库基于多线程和STL技术开发,不能用在手机等移动终端开发平台上,因此需要设计与实现一种能够应用在手机上的移动终端流媒体传输协议。这种称为WMSRTP的协议完全基于RTP协议原理,并结合上述算法进行性能优化,从而保证传输的服务质量。通过构造测试模型进行检验,表明WMSRTP可以与RTP兼容。将WMSRTP与通用JRTP类库进行比较,前者显示出在无线传输领域具有更强的针对性,其工作的实践意义是显而易见的。更多还原

【Abstract】 Media streaming technology is one of the hotspots in recent research of networking domain. With the development of mobile communication, this technology is applied more and more to the mobile devices. Media streaming on mobile device also follows the three common requirements, which are being real-time, flatness and synchronization. Designing a high-power transport protocol plays a crucial role in carrying out the object.Real-time Transport Protocol, called RTP for short, is the mainstream during all kinds of transport protocols. It makes use of UDP to transfer media data, because UDP helps to improve the real-time ability. At the same time, it collects the state information of network, so the upper layer applications can control the transport process accordingly. That is why RTP is the first choice in media streaming transportation.Since RTP doesn’t deal with the state information itself, it is necessarily to add quality-of-service assurance in order to perfect the transport process, and the most important part is the congestion control. After analyzing the existing congestion control algorithms, a new adaptive algorithm, designed for the mobile device, is put forward. It introduces the basic theory of congestion control and makes best of the RTP framework. Using this algorithm, an integrate transport protocol library for media streaming data transmission on mobile device is designed and implemented. It overcomes the disadvantage of the universal RTP libraries, such as JRTP and CCRTP. They use multithread and STL, which are not available on mobile devices. It also enhances the quality-of-service assurance ability for it can judge the congestion state of network and adapt the transport mechanism.The tests show that the protocol library, called WMSRTP, is compatible with JRTP, one of the universal RTP libraries, and it is more suitable to be applied on the mobile devices. It proves that WMSRTP is creative and valuable.更多还原