Research On ZigBee-based Localization Technology For Wireless Sensor Networks

In recent years, with the appearance of Networks of things, the development of wireless sensor networks(WSNs) has become the focus of attention, and by courtesy of new applied technology, general-purpose sensors with small size, low cost, low power consumption has taken on a rapid development trend, and self-organizing WSNs have a very broad application prospect in environmental monitoring, smart home control and other fields. In addition, WSN positioning technology can support well a variety of applications, which grants WSNs potential applications in military signal reconnaissance, short-range communications.WSN node localization algorithms can be divided into two categories: Range-based and Range-free. In the former category, many conventional positioning system estimates the distance between two devices by the signal strength, but it takes in large ranging error in long distance, particularly when distances more than 6 meter is involved. On the analysis basis of WSN characteristics including key technology, network protocol structure, positioning method, this paper applies the ZigBee-based wireless communication technology, and proposes the self-localization TOF-based sensor node localization algorithm for WSNs. This algorithm can be divided into two stages; First, the location-known anchor nodes are used to estimate the relative positions of other anchor nodes, and the positioning model is established; Then, the estimates the tag nodes' relative position are obtained by using multilateral method in the established architecture. The simulation results show that this algorithm has a high positioning accuracy, and the positioning RMSE of anchor nodes and tag nodes are close to CRLB. On the basis of research on WSN localization algorithm, a ZigBee-based positioning system is developed, in which nodes adopt various ZigBee-supporting protocol stacks, and embed TOF-ranging engines JN5168 as a kernel node chip, and the configuration node is made by compiling different embedded programs with respect to their different function in ZigBee network. TOF data collected by reference nodes and tag nodes in ZigBee network nodes are wirelessly transmitted to the coordinator nodes; then the coordinator nodes exchanged the TOF data via the serial port and the host computer software, and provide location estimates of unknown reference nodes and tag nodes.Software interface module and the positioning algorithm module in system using multi-threaded parallel processing. Positioning algorithm module realize package via dynamic link library written in C ++ language. Software interface module is designed in C # language in WPF framework, and calls positioning results in dynamic link library via internal interface. The design leaves a flexible room for the future expansion and further development of systems, and meets the design requirements of the system.