Application Research Of Network Coding In Wireless End-to-end Network

Theoretical studies have shown that, the maximum flow of the end-to-end network is determined by the minimum cut of the network. But the traditional way of communication can not meet the Shannon limit. In 2000, R.Ahlswede and N.Cai and others put forward the concept of network coding in the article of “Network Information Flow”, and points out that throught network coding, it can achieve the maximum flow limit of the network. Network coding breaks through the traditional network store-and-forward mode, and it has became a research hotspot in recent years in the field of communication.Traditionally, the reliability of the communication system is mainly guaranteed by appropriate communication protocol. In the ground cable end-to-end network, the reliable transmission of data is mainly ensured by the TCP/IP protocol. However, in the wireless end-to-end network, due to the nature of the link, especially in long time delay and high error rate of wireless network environment like in the satellite communication system, high packet loss rate will lead to a lot of retransmission, and this will result in a sharp drop in communication efficiency. Therefore, in some wireless end-to-end network occasions, we combine error control method with the traditional TCP/IP protocol, mainly by using the method of forward error correction. This thesis is based on the predecessors' research, we put forward a remedy into the wireless end-to-end network by using network coding.Firstly, this thesis analyzes and describes how the coding and decoding works of network coding detailedly, and then compare the commonly used fountain code in end-to-end wireless network. Then we introduce network coding in end-to-end wireless network.Secondly, we insert a sub-layer between the IP layer and link layer, call it network coding sub-layer, and we define the way of how the network coding sub-layer works in both sender side and receiver side and how it the way it acknowledges, and also how the retransmission works. Based on this, we put forward two ways to improve the existing network coding protocol:(1) fixed coefficient of network coding;(2) Adaptive redundant factors of network coding.Finally, through constructing proper simulation system platform, we carry out a series of experiments to simulate and test the network coding sub-layer. We also analyze the cost bought by network coding. Simulation show that, by putting forward network coding, we can get a significant increase in end-to-end wireless network.