移动网络中TCP数据重传时间优化研究

发布时间：2018-01-09 21:49

本文关键词：移动网络中TCP数据重传时间优化研究　出处：《广西大学》2015年硕士论文　论文类型：学位论文

更多相关文章： TCP RTO 移动网络 RRC 伪超时重传

【摘要】：近年来随着通信技术的进步以及移动设备的普及,移动网络成为当今世界发展最快、市场潜力最大、前景最诱人的业务之一。TCP流作为移动网络中承载绝大多数任务的传输协议,它的性能将决定移动网络能否提供高质量的通讯服务。然而,TCP在移动网络中会发生过多的伪超时重传。这是因为在移动网络中由于无线资源控制(RRC)会在不同的状态转换,这些转换导致TCP包经历巨大的突发延时从而发生超时重传因此降低了TCP的性能。本文集中讨论了移动网络中TCP重传时间存在的问题,以期待为改善移动网络中的TCP性能提供优化策略。在有线网络中TCP使用重传时间来保证数据包的可靠传输,但由于移动网络中RRC转换的特性,使得基于有线网络设计的重传机制无法很好的适应移动网络。针对这些问题,下面是本文的主要研究工作：(1)介绍了TCP重传时间以及移动网络中RRC的相关知识,阐明了由于RRC状态转换导致的TCP伪超时重传是TCP对拥塞状态错误的判断。(2)分析并验证了这种伪超时重传对TCP协议性能的影响。伪超时重传对TCP性能的影响主要包括：降低TCP流的有效吞吐率以及增加TCP传输的延时。通过真实环境中的测试,验证了该伪超时重传直接产生多余的TCP重传包降低了有效吞吐率,以及在重传后拥塞窗口和慢启动阀门值降低、RTO值偏离正常值间接导致TCP传输延时的增加。(3)提出了对重传时间的优化策略。本文优化策略通过调整RTO值来避免伪超时重传,并在Linux内核中实现。在商用3G网络中本文进行了对比测试,结果表明该优化策略不仅减少了TCP连接的流量和完成时间、使得RTO值保持正常并且降低了TCP的重传率。最后,给出本文的总结,并就下一步研究给出方向,为在以后的工作中继续深入研究做好准备。
[Abstract]:In recent years, with the development of communication technology and the popularity of mobile devices, mobile network has become the world's fastest growing market potential. TCP flow as a transport protocol that carries most tasks in mobile networks, its performance will determine whether the mobile network can provide high-quality communication services. Too many pseudo-timeout retransmissions occur in the mobile network because the RRCs are converted in different states because of the wireless resource control in the mobile network. These transformations cause TCP packets to undergo a huge burst delay and thus cause time-out retransmission, which reduces the performance of TCP. This paper focuses on the problem of TCP retransmission time in mobile networks. In order to improve the performance of TCP in mobile networks, TCP uses retransmission time to ensure the reliable transmission of data packets, but due to the characteristics of RRC conversion in mobile networks. The retransmission mechanism based on wired network design can not adapt to the mobile network very well. The following is the main research work of this paper: 1) introduce the TCP retransmission time and the related knowledge of RRC in mobile network. This paper illustrates that the TCP pseudo-timeout retransmission caused by RRC state transition is the judgment of congestion state error by TCP. The effect of pseudo-timeout retransmission on TCP performance is analyzed and verified. The effects of pseudo-timeout retransmission on TCP performance are as follows:. Reduce the effective throughput of TCP stream and increase the delay of TCP transmission. Pass the test in real environment. It is verified that the pseudo-timeout retransmission directly produces redundant TCP retransmission packets which reduce the effective throughput and the value of congestion window and slow start valve after retransmission. The RTO value deviation indirectly leads to the increase of TCP transmission delay.) an optimization strategy for retransmission time is proposed. This optimization strategy avoids pseudo-timeout retransmission by adjusting the RTO value. The results show that the optimization strategy not only reduces the traffic and completion time of TCP connection. The RTO value is kept normal and the retransmission rate of TCP is reduced. Finally, the summary of this paper is given, and the direction of further research is given in order to prepare for further research in the future.
【学位授予单位】：广西大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TN929.5

【共引文献】