Research On Reliable Routing Protocol Based On Network Coding In Wireless Sensor Networks

Wireless Sensor Networks is a type of Ad-hoc Networks. The multi-path from the source node to sink node could be built to sense and process the information which is on the coverage of WSN by a large number of senser nodes which work cooperatively. Currently, there are three kinds of reliability protection mechanisms in WSN, including forward error correction coding(FEC), Automatic Repeat-reQuest (ARQ), and multi-path routing. These three mechanisms provide data redundancy in different ways to improve the reliability in WSN. Since the Energy limited nodes in WSN take many functions as sensing,controlling,wireless communications and so on, the energy efficient reliability protection mechanisms is very critical for WSN.In this paper, based on the research of existing reliability protection mechanisms in WSN, the reliability protection mechanisms based on network coding is studied. Aimed at the excessive data redundancy and energy consumption in existing reliability protection mechanisms, the main work, based on energy efficient, is summarized as follows:1) According to combining of network coding and multi-path flooding model, First, we establish hop-to-hop flooding model. Then, we propose a reliability protection mechanisms base on network coding.In this mechanism, all nodes encode the data it received, and sink nodes decode to recover the original data when it receive enough data. Then, we make a comparative analysis of reliability and data redundancy in single-path, forward error correction, multi-path transmission and network coding strategies. According to this analysis, it is showed that the network coding strategy is more reliable to others.And the network coding strategy Reduce data redundancy.2) Since flooding is not applicalable, we analyze and optimize a lightweight reliable routing protocol ReInForm, and propose an energy efficient reliable routing NC-RMP based on network coding. Then the message format and the protocol procedures of the improved protocol NC-RMP are introduced in detail. In NC-RMP, Sink nodes detect the gradient of each node; In the source node, the minimum data redundancy, which should meet the expectation of reliability, is calculated, then multi-path is built to meet the requirements of redundancy, at last, the raw data is encoded and send out; Intermediate nodes can re-encode the packets over the same group which it received to increase the probability of linearly independence of coefficient vectors; Sink node can decode data when it receive sufficient packets in same group. NC-RMP also periodically tests whether the reliability requirements meet the expectations of reliability or not, and a reverse path from sink node to source node is established to inform the source node mediating forward probability if it doesn't meet it. Simulation results show that, in the condition of ensuring the reliability, the NC-RMP can reduce the amount of transmission redundancy and energy consumption compared to ReInForm.Finally, the paper makes a summary and draws the prospect of research. Especially, it points out the focus and direction in the future research.