Abstract
In the harsh environment, wireless sensor networks can suffer from a significant damage that causes many nodes/links to fail simultaneously and the network to get splitted into multiple disjoint partitions. In such case, linking the separated partitions by placing the least number of relay nodes and obstacle-avoiding to re-establish a strongly connected network topology is necessary to maintain the functional operations of wireless sensor network. However, the problem of finding the minimum count and the position of relay nodes is NP-hard hence heuristics methods are preferred. In this paper, we present a novel Obstacle-Avoiding Connectivity Restoration based on Quadrilateral Steiner Tree (OACRQST) algorithm to address this problem. First, the appropriate quadrilaterals are selected to connect the separated partitions and the Steiner nodes of these quadrilaterals are found. Then the disjoint islands are connected with the triangle Steiner tree or minimum spanning tree method, which are not connected by these selected quadrilaterals. Finally, relay nodes are placed to the appropriate position according to the edges of Steiner tree to restore network connectivity. However, if the found position is in the area of the obstacle, the relay node will be placed at the position of the bordering that nearest to the found position. If the network still is not connected, the relay nodes will be placed at the appropriate position according to the bordering of the obstacle starting from the node placed at the position of the bordering nearest to the found position exploring the left rule. Extensive simulation experiments demonstrate the beneficial aspects of the resulting topology with respect to number of relaying nodes, degree of connectivity and fault resilience.
Highlights
Wireless sensor network has been used almost in anywhere, especially in harsh environment, such as, searchand-rescue, battlefield reconnaissance, underwater monitor, and so on
This paper focuses on the harsh environment, in addition to energy depletion failure, sensor network nodes may be emergence massive failure due to the influence of the external environment,in this case will lead to the destruction of the entire network, Fig. 1 shows an scene
In the Main algorithm OACRQST, firstly mark for each partition is not connected partition, deploy relay nodes obstacle-avoiding in the corresponding position along the Steiner edge respectively according the quadrilateral Steiner tree and triangle Steiner tree method, and at the same time merge each partition, eventually, algorithm execution to the 7th row, the number of partitions in the entire network will not be more than two, if the number of partitions is one, and that the entire network has been connected, the algorithm terminates
Summary
Wireless sensor network has been used almost in anywhere, especially in harsh environment, such as, searchand-rescue, battlefield reconnaissance, underwater monitor, and so on. Almost all of the literatures about solving this problem are based on heuristic algorithm to find the arrangement position, in which the most common method is the Steiner minimum tree (SMT) algorithm. A novel Obstacle-Avoiding Connectivity Restoration based on Quadrilateral Steiner Tree (OACRQST) algorithm on the basis of our previous study of quadrilateral Steiner tree algorithm [15] is proposed. It assumes each separate partition as one point. The partitions will be not connected with the quadrangle Steiner tree, employ Steiner triangular approximation algorithm (FeSTA) or the minimum spanning tree algorithm (MST_1TRNP) to deploy relay node to the corresponding position to realize the entire network connectivity. If the network still is not connected, the relay nodes will be placed at the appropriate position according to the bordering of the obstacle started from the above node exploring the left rule
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