An Improved DV-Hop Localization For Wireless Sensor Network

A wireless sensor network is constituted by a series of sensor nodes, which are random distribution. WSN is a self-organized wireless network, which aims is to perception collaborative, acquisition and processing the information of network coverage in the geographic area; and sent the information to the observer. Those features make the wireless sensor networks have an important application in transportation, environmental monitoring, and military observation and so on.The node localization as one of the key technologies in wireless sensor networks is critical for monitoring network, because the message without location will be nonsense, so how to achieve effective positioning is the foundation for Wireless sensor network. However, due to cost and technology, it can not configure the GPS for each sensor node, so the range-free localization gets more and more attention.The DV-Hop is a kind of range-free localization. It uses distance vector exchange protocol make all the sensor nodes receive the hops from the anchor nodes,then calculate the value of the average hop according to the distance and hops between the anchor nodes, and broadcast it to the network. The sensor nodes calculate the distance based on the value and hops; after the sensor node get distance from the three anchor nodes, it use trilateration method compute coordinate. The DV-Hop requires the anchor nodes with GPS positioning function, the other sensor nodes according the network connective to achieve self-localization. So it is most wildly used in current application.In the homogeneous network, the distance between the sensor nodes is fixed; therefore, the appropriate positioning accuracy can be obtained in the DV-Hop. However, in heterogeneous network, the nodes distributed randomly, the distance between nodes is not fixed, so accuracy will quickly drop. So an improved DV-Hop algorithm (BNL, Based on the number of Neighbors Localization) is proposed in this thesis, The BNL algorithm divide the monitoring the area into several subdivided, according to the number of nodes within the region to estimate the hop distance, so as to avoid distance between the nodes is not fixed in heterogeneous Network on the estimated impact of hop distance. At the stage of coordinate calculation, the BNL weighted average number of hops between the sensor nodes and anchor nodes to reduce the mistake by the Multi-hop in the network.The simulation and experiment results show that the BNL can improve the positioning accuracy more effectively without increasing hardware consumption in nodes comparing with conventional DV Hop algorithm. So it is a practical and effective node localization method in wireless sensor networks.