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The Optimization Techniques Of Coding Node In Wireless Network

Posted on:2016-10-13Degree:MasterType:Thesis
Country:ChinaCandidate:H ZhangFull Text:PDF
GTID:2308330461469214Subject:Communication and Information System
Abstract/Summary:PDF Full Text Request
In the multicast network, the using of network coding (network coding, NC) technology can improve the utilization rate of the cyber source, while maintain the maximum multicast flow. In recent years, the network coding has been more and more widely applied in wireless networks. However, the introduction of the encoding nodes will take the corresponding actual costs as well as transmission delay of the wireless network as a price. Therefore, in the premise of maximal multicast flow, trying to make the number of the encoding nodes as small as possible can effectively improve the utilization rate of the cyber source and ameliorate the transmission performance.For the cost problem of the encoding nodes in the wireless network, this paper has done the following research work:(1) For the facts of that the cost of the network coding in the wireless network is too heavy and the utilization rate of the cyber source is too low, according to the existing encoding nodes selection algorithm in the wireless network, an improved algorithm-encoding nodes selection algorithm based on the shortest path is proposed. Based on the traditional Ford-Fulkerson max-flow algorithm, the main idea of this algorithm is to apply the Edmonds-Karp max-flow algorithm which searches the shortest path in the way of breadth first during the process of searching the augmenting path and add the concept of capacity difference into the Edmonds-Karp max-flow algorithm. Firstly, using the breadth first search algorithm to find the shortest path from the source node to the destination node in the network, to compare the path capacity difference, and to augment the path which has the maximal difference, and thus the max-flow path set from the source node to all destination nodes can be got. Secondly, using the improved coding criterion to lock the encoding nodes in that max-flow path set. Then through case analysis, in the premise of maximal multicast flow, this improved algorithm obviously has fewer steps during searching the max-flow path than the traditional Ford-Fulkerson algorithm. Finally, by analyzing the characteristics of the wireless network, the wireless network model can be established on the Matlab simulation platform. So, by using the improved algorithm this paper has proposed, we can emulate the max-flow path and the distribution characteristics of encoding nodes of the improved algorithm and the traditional algorithm. The Simulation result shows that the times of that the number of the encoding nodes equals to 1 is the biggest in the improved algorithm, while that in the traditional algorithm equals to 3. As a result, the improved algorithm can effectively reduce the number of encoding nodes as well as the network costs.(2) For wireless sensor networks, the algorithm is improved according to the traditional network coding. Combined with the multicast max-flow path searching algorithm and the node centrality, a selection scheme of network coding nodes based on the node centrality is proposed. Firstly, analyze the characteristics of the wireless sensor networks and the constraint of the sensor node. Secondly, analyze the sociality of nodes in the wireless sensor networks; then according to the different network traffic, select the intermediate nodes for information transmission dynamically. Then, select the shared node from the multicast max-flow path; analyze which shared nodes should be viewed as coding nodes through the coding node criterion; and open the code function on the coding node which meet the conditions and turn off the trigger after finishing the coding. Finally, establish the model of wireless sensor network on the Matlab simulation platform; compare the distribution trend of the number of the relay nodes under the condition that the improved NC algorithm and the traditional NC algorithm have different destination nodes number. The Simulation result shows when the destination node number is 8, the number of relay nodes of the improved NC algorithm is nearly 36.4% less than that of the traditional NC algorithm.
Keywords/Search Tags:Network Coding for Wireless Network Coding, Encoding Node, Shortest Path, WSN, Node Centrality
PDF Full Text Request
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