Research On Multi-path Reliable Transmission Algorithms Based On Network Coding For Ad Hoc Network

Ad Hoc network is a self-organizing network with no center. According to the advantages of flexible, rapidly spread, distributed control and many others, Ad Hoc network is widely used in military field and emergency communication environment. Since the Ad Hoc network has the features of dynamic topology changes,high channel bit error rate and limited node energy, reliable transmission of data faces severe challenges.Combined with network coding and multipath routing technology, the Ad Hoc network reliable transmission algorithm is put forward. Algorithms include three maintenance which are multi-path routing discovery, data transmission and routing information. In routing discovery phase, source node sends the routing requests, according to the link error rate information and nodes information that intermediate nodes collected, destination nodes calculate the number of the multipath which meet the desired data needed for the successful transmission, the priority section are that paths having the high qualities. And then response to the source node to let the source nodes know the select transmission paths. Intermediate nodes in the path update the local routing table. In data transmission phase, the source node to send data by random linear network coding, and then the encoded packets have been sent out through those multiple paths. If intermediate nodes receive several encoded packets from the same source node with the same code grouping, the intermediate do as intra-flow network coding. If the encoded package come from different nodes, and can meet the licensing conditions, then use the inter-flow network coding to improve the throughput of network. Destination node recovering the original data after receiving the code package decoding. Information maintenance phase update the nodes information table through detecting the node grouping link-state and neighbor nodes information, and provides the basis for judgment for the discovery of multiple paths and encoding condition.NS2 network simulation software is used for simulating the performance of the proposed algorithm and simulation algorithm characteristics. The results show that this designed algorithm has reached the requirement of network for data transmission reliability, while reducing the end-to-end delay and improve the network throughput.