Design And Positioning Research Node ZigBee Wireless Sensor Networks

Along with the Wireless Sensor Networks develops toward the direction of miniaturization,intellectualization, multi-function and short distance wireless communication technology ZigBeebecomes mature. Design out a flexible, high-efficient, scalability, compatibility, low powerconsumption node and to realize its positioning become a very meaningful subject that need for alarge number of research from theory to practice.First, starting from theoretical point, analysis and presentation of the study background,Wireless Sensor Networks and ZigBee technology. Including Wireless Sensor Networkarchitecture, network topology, Characteristics of ZigBee technology and basic functions of theZigBee protocol stack layers.Second, starting from the Wireless Sensor Networks node design principles, Design out asensor node which is use low power consumption MCU chip ATmega128L and RF chip CC2420as the hardware core. Completed design of processor module, wireless communication module,sensor module, power supply module and each module drivers of node embedded operatingsystem TinyOS. Used nesC language writing data transceiver program to realize the reliablecommunication between nodes.Third, in order to realization of the node positioning function, analysis of various positioningalgorithm, then proposed an improved positioning algorithm based on RSSI ranging principle.This improved algorithm use Bayesian probability model to retain the signal intensity distributioninformation as integrity as possible. Then use the triangle centroid algorithm to obtain nodecoordinates. Finally, refinement the coordinate values several iterative to arrival at a final stablevalue. The simulation result shows that the improved algorithm will still able to achieve highpositioning accuracy even in the case of a lower proportion of anchor nodes, Compared with thetraditional RSSI positioning algorithm the performance has improved greatly.Finally, combined with the development direction of the Wireless Sensor Networks, give abrief introduction of underground personnel positioning system, and reasonable downhole nodedeployment program.