Research On Data Transmission Performance Based On Network Coding In Wireless Ad-hoc Networks

In traditional wireless ad-hoc networks communications, intermediate node in wireless ad-hoc networks is responsible for receiving the information data which is from adjacent nodes, then it stores and forwards the received information data. Because the wireless ad-hoc networks communication is instability, the link and the nodes of link is variability. Compared with wired networks, the wireless ad-hoc networks data transmission has a lower efficiency. The wireless ad-hoc network uses network coding in data transmission, and then the intermediate network node of link receives the data transmitted from its neighbours. This procedure codes the received data selectively, which changes the traditional storage-forward communication model and promotes the throughput of wireless ad-hoc network data transmission as much as multicast network communication’s. Therefore, when the network coding technologies apply to wireless ad-hoc network data communication, it can improve the throughput of network data and efficiency of network transmission significantly. In addition, this technology can reduce the packet losing in data packet transmission and enhance the instability of wireless self-organized network. Network data transmission performance affects the application of network coding and the new protocol design and implementation in wireless self-organized network. Therefore, in current wireless self-organizing network data communication, data transmission performance limits the development of network coding technique and new relevant protocols. The thesis discusses the analysis method and optimization technique of data transmission performance in wireless ad-hoc network communications, and proposes relevant solutions.After wireless ad-hoc network data transmission path was researched, we proposed a multi-path data transmission strategy based on network coding. With the help of multi-path routing discovery technology, the source node builds data transmission path sets belonging to different destination nodes in wireless ad-hoc network. When the source node transmits data to the destination node, the source node chooses several suitable paths from the path set to transmit data packets synchronously, which greatly reduces transmission delay of single link. In addition, the source node executes the pre-coding operation on the data to be transmitted and the destination node executes the decoding operation on the received data. At the first node on the common link of different path sets, coding operation is executed on the data packets from different source nodes. At the last node, decoding operation is executed, and data packets are broadcast to appropriate destination nodes according to the record of the packets’head. Finally, a multi-path data transmission network prototype, which supports network coding, is constructed to validate the proposed strategy on NS-2 simulation platform. Experimental results show that the transmission delay and the retransmission times are reduced by the use of the strategy so that the transmission efficiency of wireless ad hoc network is promoted obviously.In terms of code executing efficiency, related work is researched and a control strategy about network node transmission speed is proposed. By the use of the strategy, when the network node receives the data information from adjacent node, appropriate transmission speed is selected adaptively to execute transmission operation. Thus, in a certain time interval of wireless ad hoc network transmission, the account of data information listened and received by the common node of the link is similar. Meanwhile, the rate and efficiency of data coding operation achieves the optimal state. In virtue of network coding control strategy, the data traffic in wireless ad hoc network communication link is reduced, the network transmission capacity is increased and network data transmission performance is promoted. After the theoretical analysis, simulation experiments are taken by the use of NS-2 simulation environment. Experimental results show this strategy can effectively increase the performance of data coding efficiency from different links, reduce the amount of data traffic, and improve data transmission performance in wireless ad hoc network.