Research And Implement Of Self-adaptive Transport Protocol Based Block Coding For The Wireless Network

Initially, Transfer Control Protocol was designed for providing wire link reliable transmission, this design regarded packet loss as sign of network congestion, thus reduced the transmission rate. However, the reasons of packet loss usually are signal attenuation, connection interruption, signal interference, and the Transfer Control Protocol's strategy that blindly reduces the transmission rate cannot meet the demands of transmission. Research showed that network coding scheme can avoid the effect of packet loss on the link, and network coding technology can provide new way to solve the problem of wireless network transmission.Firstly, this article analyzed the problem of TCP protocol in the wireless network transmission, and summed up the relevant solutions and research status; introduced the basic concepts of Random Liner Network Coding, illustrated it's performance improvement principle under the condition of packet loss in wireless network; specifically focused on the CTCP protocol which is based on Random Liner Network Coding technology, described CTCP protocol's block coding, reliability and congestion control mechanism, and analyzed the problem of existing scheme.Secondly, after analyzing CTCP protocol's transmission mechanism, we designed BCD-WTP protocol which uses Self-adaptive strategy. BCD-WTP protocol's frame stems from CTCP's, which mainly includes parameter estimation module, block transmission module, coding module and congestion control module. BCD-WTP protocol improved CTCP protocol's static transmission control, estimated the parameters in wireless network in real time, adjusted transmission strategy according to the parameters, and adapted the high packet loss rate.Thirdly, we implemented BCD-WTP protocol on the application layer of Linux system. We introduced BCD-WTP protocol architecture and the main function's parameters and detail; emphatically introduced the procedures of network parameters estimation function, block transmission function, sending packet function and the decoding function.Finally, we experimented on the Linux system; observed and calculated TCP, CTCP and BCD-WTP's transmission performance in high packet loss rate environment. Experimental results show that, BCD-WTP protocol improved its performance in high packet loss rate environment, could adapt bandwidth's change in real time, and adjusted act of sending.