Research And Implementation Of New Transport Protocol Based Network Coding For The Wireless Network

Due to the essential differences between the characteristic of wired and wireless network, such as unstable, high BER, long RTT during transmission. TCP is restrained in such condition; TCP protocol can’t meet the need of wireless network’s development.Thereby, nowadays it has become a one of hot topics in wireless network areas to make wireless transmission more reliable and efficient. Besides due to wireless link’s unreliable and broadcast by nature. It is more propitious to apply network coding to wireless network, network coding technologies emerge provides new approach and challenge to solve this problem. Based on the above problems, this paper studies the content from the following four aspects. On the basis of the research background, this paper researches into the following four aspects:Firstly we introduce the research status to improve wireless transmission and analyzed the problems emerging in the combinations of traditional TCP and wireless network, we also analyze several classical improving scheme and concluded the advantages of using network coding technology to solve the transmission problems in wireless network. The concept of RLNC(random linear network coding) and TCP/NC protocol are emphasized.Secondly, after analyzing the shortcoming of existing scheme combine network coding and TCP, we introduce the design of TCP-NCAR based on the basic framework of TCP/NC. We redesigne ACK packet feedback mechanisms, the packet format coding segment, redundancy dynamic adjustment algorithm, The core of the new protocol is a new interpretation of ACKs and the new packet-state feedback mechanism and the self-adaptive retransmission based on decode matrix state. We also demonstrate the improvement of TCP-NCAR is effective.Thirdly, we develop the model of TCP-NCAR and TCP/NC in the environment of OMNET++. We introduce the dynamic retransmission algorithm in sender module, the decode matrix feedback algorithms in receiver module.Finally, On OMNeT++ simulation platform we evaluate TCP-NCD through a lot of simulations, we set up some parameters, such as, transmission rate, transmission distance, file size, packet size, packet error rate, etc, and run TCP-NCAR and TCP/NC,compared with and analyze the performance difference between the two protocols, verify the transmission performance of TCP-NCAR in case of high BER rate and dynamic BER.The results show that performance of TCP-NCAR is better than TCP/NC, particularly in TCP-throughput, size of decode buffer, and the reliability of data transmission.