Link Correlation Aware Opportunistic Routing Based On Network Coding

Opportunistic routing greatly increases transmission reliability and network throughput by taking advantage of the broadcast nature of the wireless medium. Meanwhile the network coding are sufficient to achieve the maximum capacity bounds.With network coding, opportunistic routing can be implemented in a simple way, also can significantly improve the network throughput.Until recently, modeling wireless links had always considered link errors to be independent between neighboring nodes.In such an assumption and given a specific error rate, if a node received a packet in error, it will not have any influence on weather or not its neighbor node receives the packet in error.However, recent works have shown that correlated shadowing and interference might lead to correlated packet errors between neighboring receivers.Link correlation has significant effects on diversity based algorithms in wireless networks such as opportunistic routing, network coding.The main research work of this article includes the following two aspects:In order to provide a simulation environment is more close to the actual wireless network, we established the mathematical model of link relevance, and has expanded in the network simulator NS2.The specific implementation is the use of mathematical model of correlation adds a new loss model in NS2.The loss model is divided into link interference effects and without external interference effect.Link without external interference, packet loss is independent, when subjected to external disturbance,link loss rate will increase and the correlation between links.Simulation results show that, when the different link by a virtual interference effects, will show link correlation. Without the link interference, is still arandom and independent.A typical combination of network coding opportunities routing protocol forwarding node forwards when estimating the number, there will be deviations.Then opportunistic routing protocols will not work better than the shortest path protocols, as there is no spatial diversity to exploit.To solve this problem, we re-analyzed the formula to estimate the number of forwarding node forwards and propose a more reasonable formula, the formula combines the typical combination of network coding opportunistic routing protocol. And analyze the performance of the improved protocol by simulation experiments. Experimental results show that the improved protocol appears correlation network, the network throughput can be further improved.