Realization Of Wireless Sensor Network’s Node Localization On STM32W

Wireless sensor network(WSN) has broad application prospect in the monitoring areas of national defense and military, environmental monitoring, smart home, etc. In the monitoring system, the data that collected from sensors have practical significance only when it bind to specific position information, but in some practical application, the randomly distributed wireless sensor network nodes or the mobile nodes usually cannot know their locations in advance. Therefore, the wireless sensor network should adopt certain method to realize node self-localization, which lays the foundation for the system to achieves precise data acquisition. The design of the localization system in this paper uses the weighted centroid localization algorithm based on RSSI and realizes the unknown nodes localization.Beginning with the node design, the paper first introduces the hardware design of nodes of WSN. The design uses the high-performance SOC-STM32W108which produced lately by ST as its master and extends peripheral circuit and its drivers, the peripheral circuit including the SD card interface, etc. The STM32W108made the peripheral circuit design conveniently. Then the paper introduces the way that uses the protocol stack of EmberZNet to design ZigBee network. On localization algorithm, the paper studys the principles of range-based localization algorithms and range-free localization algorithms carefully and chooses the weighted centroid localization algorithm based on RSSI by comparing and analyzing two types of localization algorithms. The algorithm reflectes reasonably that different anchor nodes have different bindings to locate unknown node by using the RSSI as weight coefficient, and it improves the precision of using centroid location algorithm and needs no additional hardware. By the way, the communication overhead of the algorithm is small. Finally, the paper finished the software design of node localization. This part use the idea that unknown nodes send the message which were got from around anchor nodes when them joined the ZigBee network, and the center node realizes the location calculation. The idea reduces the communication overhead and easy to achieve.The test results show that the localization system be able to achieve self-positioning of the wireless sensor network’unknown nodes, and have a high location accuracy in an open area.