A Study Of Localization And Tracking Algorithms In Wireless Sensor Network

With the rapid development of micro-electromechanical systems and wireless communication technologies, there was an emerging technology-A large-scale wireless sensor network (WSN) consists of a large number of inexpensive, small sensors. Wireless sensor networks have been widely used in many fields, such as strategic regional monitoring, navigation, underground personnel positioning and tracking, etc. The key technology of wireless sensor networks is to locate and track the target, so, choose a good localization algorithm is particularly important.Localization algorithm is usually classified according to whether based on range. Range-based localization algorithm has a high positioning accuracy, but requires additional hardware support; Range-free localization algorithm has lower cost, but the positioning accuracy is low. When choosing the localization algorithm, we should according to the actual application environment and requirements.This paper selected rang-based localization algorithm to study the location of the unknown node at static or a moment. First, we introduced the multilateral localization algorithm based on RSSI (Receive Signal Strength Indication), analyzed and pointed out that those algorithms has low positioning accuracy, poor robustness. To solve the problem, this paper presents an improved algorithm-based on the Newton iteration with RSSI localization algorithm (NIRL).We give the unknown node an initial coordinate, then we expand the group of binary quadratic based on RSSI with Taylor Series at the point of initial coordinate, omit quadratic and higher, we get a linear equations.at last, we apply iteration algorithm to estimate the real coordinate of the unknown node. With the results of simulation, NIRL has higher accuracy, better stability than the multilateral algorithm, the only downside point is that NIRL has more computation than multilateral algorithm, but it has little effect on the energy consumption of the entire system.For the research of mobile node in wireless sensor network, this paper uses a tracking algorithm based on the Kalman filter. First we should establish a mathematical model based on the trajectory of the target node, if the mathematical model is a linear system, we can use the tracking algorithm based on the Kalman filter; or, we have to using the extended Kalman filter for the nonlinear systems. The extended Kalman filter algorithm is obtained by the Jacobi matrix which simplified the system into linear. With the results of simulation, the Kalman filtering algorithm can be effective on the tracking of the target node.