The Research And Implementation Of Networking Technology For Zigbee-based Indoor Positioning System In Hospital

As development of wireless communication technology, indoor positioning system gets more and more attention. ZigBee technology, due to its low cost, low power consumption, high reliability features, provides a good solution for the achievement of positioning system. However, in the hospital indoor positioning system oriented to the medical application, ZigBee network nodes will reach thousands more, for battery-powered nodes, there are multi-level routing energy cost. Based on a single network coordinator, the ZigBee network actually contains up to three or four hundred nodes. Meanwhile, based on a single network coordinator ZigBee networking, load pressure to transfer data, severe packet loss rate, and network performance significantly decreased; and coordinator failure will result in paralysis of the entire network.To address the above issues, this paper, in the background of the indoor positioning system in a hospital, based on the analysis of ZigBee protocols and networking technologies, proposing a multi-subnetwork switching mechanism, which integrates RFID technology, devide a large ZigBee Mesh network into multiple smaller subnets, RFID ID associated with the subnet information in the reference nodes of the network, by comparing the network information in the reference node and blind node is the same to determine whether to switch between different subnetworks. Meanwhile, this paper also presents a dual coordinator redundancy fault-tolerant mechanism, the coordinator backup node,every 1 second actively querys coordinator working condition to detect faults, once finding a fault and after confirmation by the host computer, the backup node take over the work of the fault coordinator .On the basis of the above work, this paper integrates zigbee application development platform in software and hardware , to achieve fault-tolerant and multi-subnetwork switching mechanism of Zigbee mesh network and do experimental analysis, and in a Zigbee-based indoor positioning system in hospital. Experiments and application show that this networking mothod significantly reduces the information delays in data transmission and feasible and effective. Comparing other indoor wireless loaction systems, this work of this paper has the following characteristics:(1) Propose a multi-subnet switching mechanism to establish a network. For a large-scale indoor positioning ZigBee network , that containing more than 3,000 nodes, integrate the ZigBee and RFID technology, through the use of positioning the node with the host computer requests - response model, to determine whether the network need to switch, this method effectively reduces the network load pressure, improving network reliability.(2) Based on the above prototype networking system, provide fault detection and fault tolerant recovery mechanism. Backup route periodic testing status of coordinator node , if continuously not receive a reply from the coordinator three times, coordinator backup node sends message to PC to check whether the coordinator is a failure; then backup node which has copied the program of coordinator is called and replaces the failed coordinator,ensure network stability.