Research On Network Coding Nodes Selection In Wireless Network

In the multicast network, network coding has proven to be an effective technique to obtain the maximum flow capacity. Meanwhile, it can increase the throughput, improve the load balancing, reduce transmission delay and enhance robustness of the wireless network. Although network coding has the advantage of improving the performance of wireless networks, the encoding nodes increase the network cost and delay. Therefore, minimizing the number of encoding nodes is of great significance on optimizing the performance of the actual network under the precondition of ensuring multicast transmission rate.This paper achieves partial improvements on the basis of the existing algorithm focusing on the selection of network-coded nodes in wireless networks. The introduction is as following:(1) Based on depth-first technique to find network-coded nodes, this algorithm is proposed aiming at the shortage of the current algorithm, in which needs more computing and more encoding nodes. The basic thought of the algorithm is first to calculate the max-flow paths from one single source to other destination nodes by the depth-first technique, then analyze nodes in the paths, finally generate conditional network-coded nodes. By comparison with the Ford-Fulkerson algorithm for the multicast maximum flow algorithm, the algorithm proposed in this paper can reduce the number of searching max-flow paths and avoid double counting problem of intermediate nodes effectively. When the output links starting from the source node or the input links ending from the destination nodes are in the state of saturation, we use the termination character to mark the links, which has the characteristics of easy understanding and strong visualizability. On the basis of the wireless network model, this paper also presents an applicable implementation of the proposed algorithm. The simulation analyzes the distribution of encoding nodes and maximum flow, and also shows that the network size and effective communication radius have an influence on the number of network coding nodes. Simulation results show that the proposed algorithm reduces the number of encoding nodes obviously while achieving the multicast maximum flow.(2) Based on the seldom research of network coding nodes selection in the dynamic network, this paper proposes a selecting scheme of encoding nodes in the dynamic self-organized network. In order to guarantee the stability of changes in wireless network, we build the route through a prediction model which takes account into the influence of link quality. This prediction model mainly predicts the locations of all the nodes and the transmission time before link breaks. Then we select the stable nodes from the route to execute the processing of network coding, which could enhance the stability of the network structure. Through theoretical analysis and simulation, we show a comparison of redundancy and transmission efficiency before and after the application of network coding.