Study Of Three-dimensional Positioning Algorithm For Wireless Sensor Network Node

With the development of sensor technology, detection technology, and the wireless network technologies, Wireless Sensor Network technology is playing an increasingly important role in scientific researches. The positioning algorithms of WSN are needed in order to connect the detection information of sensors to the real locations. The current positioning algorithms of wireless sensor network are mostly under the two-dimensional assumption, and they can perform well in small regions or flat areas. When under the three-dimensional assumptions, errors introduced by many factors such as communication barriers and higher dimensions will reduce the accuracy of positioning algorithms. Therefore, it is a very practical and significant project to promote the mature two-dimensional positioning algorithms to three-dimensional fields.According to the different targets of positioning, this issue of wireless sensor network can be divided into two stages. The first stage is to identify the entire network after the initial layout of sensors. The latter stage is to locate individual node after the entire network has been identified. According to the different objectives of two phases, this paper uses two customized WSN (Wireless Sensor Network) three-dimensional location methods for the two conditions.In the initial phase of the global positioning, we improved a two-dimensional algorithm based on anchor promotions. The advantage of the method is that it only requires a small amount of anchors to locate all unknown nodes in the network. Its drawback is when the anchor nodes are too rare and their distribution is relatively concentrated, the errors will increases rapidly away from the region of anchors. In extended to three-dimensional process, this paper finds the geometric relationship between nodes firstly and introduces new reference node selection criterion and new targets of optimization. As the electronic map information has been very popular at the present, so this paper introduces the map information in the optimal design to reduce the positioning errors. In addition, we propose two improved strategies to find the right location: dynamic optimization of threshold and improved anchor node selection strategy.If some individual nodes need to move after the completion of global positioning, it is necessary to design new strategy to relocate them. This paper promotes the APIT algorithm to complete the positioning under this case. The advantage of this approach is that it is fast and simple. This paper designs a protocol using the three-dimensional positioning APIT algorithm firstly, and this protocol specifies the actions of nodes and the information collected for the computing stage. Then we introduce the three-dimensional extension of APIT algorithm. First extend the geometric relationship between the regions and nodes to three-dimensional, and then introduces the map information to its optimization stages to make the method both efficiency and accuracy.Both methods above are simulated by Matlab in windows platform. The simulating results show that both algorithm and protocol can provide considerable location performance under different conditions. The proposed algorithm is more close to the actual situation because of the three-dimensional assumption, which can be applied in complex terrain or under a wide range of Wireless Sensor Networks.