Design And Implementation Of Hibernation Strategy Based On Z-Stack Protocol Stack

The number of terminal nodes in ZigBee star network is normally huge.In the process of communicating with the coordinator,if the control of transmission is not well proceeded,it will cause data conflict easily,and resulting in data re-transmission.Using time division multiple access hibernation enables only one terminal node transfer data to the coordinator in the ZigBee star network at a time slot.Thus it improves the quality of the network communication.Since time synchronization of each terminal node is the the basis to ensure time division multiple access hibernation in ZigBee star network,to research on the accurate time synchronization algorithm and realization of time division multiple access hibernation scheduling has great significance to avoid the conflict of ZigBee star networks.In this thesis,it expounds the importance of time synchronization in wireless sensor networks,and compares RBS,DMTS and TPSN,the three kinds of time synchronization algorithms.After analyzing the energy consumption and accuracy of these three kinds of the algorithm,it is determined that the TPSN algorithm is adopted to realize the time synchronization.Since TPSN algorithm fails to consider the clock drift,in this thesis,the time synchronization TPSN algorithm needs to be improved,and the modified TPSN + algorithm considers the clock drift factor,which can make the terminal nodes and the coordinator to realize time synchronization.After that it analyzes the principle of time division multiple access wireless communication protocols and the application of the Z-Stack protocol stack in ZigBee network.According to the coordinator broadcasts time slot allocation table,terminal nodes use time slot in the time slot allocation table to set the timer interrupt to hibernate and wake up,which realizes the ZigBee star network time synchronization and time division multiple access hibernation.Finally,a temperature and humidity monitoring system of ZigBee star network is set up to measure the clock drift,set the time synchronization and realize the time division multiple access hibernation function in this thesis.Experimental results show that adopting the modified TPSN +algorithm and time division multiple access hibernation strategies enables each node to alternate between hibernating and waking up on the basis of the time synchronization,and achieve the desired result.