基于块编码的自适应无线网络传输协议设计与实现

发布时间：2018-03-05 05:25

本文选题：随机线性网络编码　切入点：无线网络　出处：《国防科学技术大学》2014年硕士论文　论文类型：学位论文

【摘要】：传统传输控制协议TCP(Transfer Control Protocol)最初的设计目的是提供有线链路的可靠传输,这种设计把丢包作为网络拥塞的标记,从而降低发送速率,避免出现更大的拥塞。然而在无线网络中,引起丢包的原因通常是信号衰退、连接间断、信号干扰等物理现象,TCP协议盲目降低发送速率的策略不能满足无线网络的传输需求。相关研究表明网络编码方案能够避免丢包对拥塞控制造成的影响,网络编码技术可以为无线网络传输存在的问题提供新的解决思路。本文的主要工作有:首先,分析当前TCP协议在无线网络传输中所存在的问题,并总结当前提出的相关解决方案和研究现状。介绍随机线性编码技术的基本概念,阐述其在无线网络丢包情况下的性能提升原理。重点介绍基于随机线性编码技术的CTCP协议,对协议的块编码、可靠性以及拥塞控制等机制进行详细的描述,并对CTCP现有方案中存在的不足进行分析。其次,经过分析CTCP协议的传输机制,设计一种采用自适应策略的BCD-WTP协议。BCD-WTP协议的框架源于CTCP,主要包括网络参数估算模块、块传输模块、编码模块、拥塞控制模块和解码模块,改进CTCP协议静态的传输控制行为,实时估算无线网络环境中的参数,并根据参数调整传输的策略,适应高丢包率的无线网络环境。再次,在Linux操作系统应用层实现BCD-WTP协议。介绍BCD-WTP协议的结构以及模块中主要函数的参数与实现细节,并着重介绍了网络参数估算函数、块传输函数、发送报文函数与解码函数的流程。最后,在Linux系统进行实验,观察和计算TCP、CTCP和BCD-WTP协议在高丢包率的环境中的传输性能。实验结果表明,BCD-WTP协议在高丢包率的环境中的传输吞吐量有明显的提升,并且可以实时适应带宽的变化,及时调整发送行为。
[Abstract]:The traditional transmission control protocol, TCP(Transfer Control protocol, was originally designed to provide reliable transmission of wired links. This design uses packet loss as a sign of network congestion, thus reducing the sending rate and avoiding greater congestion. The cause of packet loss is usually signal decay, disconnection, Some physical phenomena, such as signal interference, can not meet the transmission requirements of wireless networks because TCP protocol blindly reduces the transmission rate. Related studies show that network coding schemes can avoid the impact of packet loss on congestion control. Network coding technology can provide a new way to solve the problems in wireless network transmission. The main work of this paper is as follows: firstly, the problems of TCP protocol in wireless network transmission are analyzed. The basic concept of stochastic linear coding is introduced, and the principle of performance improvement in wireless network is expounded. The CTCP protocol based on stochastic linear coding is introduced emphatically. The block coding, reliability and congestion control mechanisms of the protocol are described in detail, and the shortcomings of the existing CTCP schemes are analyzed. Secondly, the transmission mechanism of the CTCP protocol is analyzed. A framework of adaptive BCD-WTP protocol .BCD-WTP is designed, which includes network parameter estimation module, block transmission module, coding module, congestion control module and decoding module to improve the static transmission control behavior of CTCP protocol. The parameters in wireless network environment are estimated in real time, and the transmission strategy is adjusted according to the parameters to adapt to the wireless network environment with high packet loss rate. BCD-WTP protocol is implemented in the application layer of Linux operating system. The structure of BCD-WTP protocol, the parameters and implementation details of main functions in the module are introduced, and the network parameter estimation function and block transfer function are emphatically introduced. The flow of sending message function and decoding function. Finally, the experiment is carried out in Linux system. The transmission performance of TCP / CTCP and BCD-WTP protocol in high packet loss rate environment is observed and calculated. The experimental results show that the transmission throughput of BCD-WTP protocol in high packet loss rate environment is obviously improved, and it can adapt to the change of bandwidth in real time. Adjust the sending behavior in time.
【学位授予单位】：国防科学技术大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TN915.04

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