【作者】 黄辉；

【导师】 许长桥；

【作者基本信息】 北京邮电大学 ， 计算机科学与技术， 2016， 硕士

【摘要】 近年来,随着无线接入技术的快速发展,现有的大量终端设备普遍装备了多个网络接口接入互联网。用户可以同时使用多个网络接口,通过带宽汇聚的多接口数据并行传输的方式支持高效的业务传输。另外,快速发展的移动互联网,推动了大量具有不同特性的新业务涌现,比如实时流媒体服务等。然而,受限于传统TCP/IP协议栈分层设计思想的限制,现有的传输协议难以获取到其他协议中的有用信息,无法认知上层业务的特性和感知底层网络环境动态变化,从而影响传输的性能,不能很好的满足用户的体验质量。针对上述问题,本文基于并行多路径传输协议MPTCP,提出无线网络环境下业务特性驱动的并行数据传输技术解决方案。本文主要工作包括:(1)提出了一种业务特性感知方案,通过对上层业务的感知并获取业务相关的特性,用于指导传输模块的决策;(2)提出了一种传输质量评估方法,该方法基于上层的业务特性与传输层的传输状态,能实时评估传输质量,并依据传输质量动态调整传输策略;(3)设计了一种基于权重的数据调度算法,该算法综合考虑了影响MPTCP传输效果的两个重要因素,RTT和丢包率,通过权重控制机制实现了高效的数据调度;(4)提出了一种动态分包算法,该算法能够根据网络环境变化动态调整数据包的大小,减少带宽资源的浪费;(5)设计了 MPTCP的部分可靠传输拓展(PR-MPTCP),能根据当前的状态决定是否开启部分可靠传输模式,主动丢弃过时的数据,减少无效数据包的重传,同时减少队首阻塞的次数。所在课题组与华为公司联合提交了一份关于PR-MPTCP的IETF草案。本文采用主流的网络仿真软件NS-2进行有效性验证和性能评估。对FTP、CBR、基于RTP的业务的传输效果进行了评估,结果显示所提方案在面向不同特性的业务时能够较好地满足其传输需求。同比较对象相比,基于RTP的业务可以获得更好的播放体验,而FTP等业务能够获得更高的服务质量(QoS)。此外,动态分包算法可以有效减少带宽资源的浪费。更多还原

【Abstract】 In recent years,with the rapid development of wireless access technology,more and more terminal devices are equipped with multiple network interfaces connected to the Internet.Users can utilize multiple network interfaces to get efficient delivery service through bandwidth aggregation.In addition,the rapid development of the Mobile Internet pushes a large number of new services which have emerged with different features,such as real-time streaming media services,etc.However,subject to the limitations of conventional TCP/IP protocol stack layered designing,existing transmission protocols are difficult to get useful information from other protocols,and they can not inspect upper layer service and perceive the features of underlying dynamic network environment.Thus,the transmission performance is impaired and can not satisfy the user’s Quality of Experience.To address the aforementioned problems,this dissertation proposes service-features-driven concurrent multipath transmission scheme in wireless networks based on the Multi-path Transmission Protocol(MPTCP).The proposed scheme consists of the following contributions:(1)A scheme for service features perception by perceiving the upper layer service and obtaining service-related features used to guide decision-making of transmission modules;(2)A method for transmission quality assessment based on the features of the upper layer service and the state of transport layer transmission which can be used to assess the real-time transmission quality,and dynamically adjusts the transmission policy based on the transmission quality;(3)A weight-based data scheduling algorithm concerned about two important factors affecting MPTCP transmission performance,including round trip time and packet loss rate,with weight control mechanism to achieve an efficient data scheduling;(4)A packetization algorithm which can dynamically adjust packet size according to the changes in the network environment,in order to reduce the waste of bandwidth resources;(5)Based on the above work,designed a Partially Reliable MPTCP extension(PR-MPTCP),by discarding outdated data to avoid retransmiting invalid packets,while reducing the number of the Head of Line Blocking.This project group cooperated with Huawei and had submitted a draft about PR-MPTCP to Internet Engineering Task Force(IETF).In this dissertation,the popular network simulation software NS-2 was used for effectiveness validation and performance evaluation.Transmission performance of service,including FTP,CBR and RTP-based service,are evaluated.The results demonstrate the proposed schemes can better meet the transmission needs for the different features of services.Through the comparison,RTP-based service can obtain a better playback experience,and FTP and other services can get a higher quality of service(QoS).In addition,the dynamic packetization algorithm can effectively reduce the waste of bandwidth resources.更多还原