Research And Development Of ZigBee Wireless Sensor Network Based On ARM&LINUX

Clock synchronization plays a fundamental role in the operation of wireless sensor networks and is very important for various tasks such as coordinated sleep and wakeup modes for energy conservation, object tracking, data fusion, etc. Since wireless sensor networks are limited in energy, cost and complexity, traditional time synchronization algorithm like Network Time Protocol (NTP) and Global Position System (GPS) are impractical to synchronize the wireless sensor network. For the characters of the wireless sensor networks, it has proposed a lot of protocols, such as RBS, TPSN, FTSP and so on.After the intensive research of existing time synchronization technology and algorithms, an improved time synchronization algorithm is presented based on the TPSN. The TPSN algorithm consists of two phases: level discovery phase and synchronization phase. In the discovery phase, the improved algorithm selects the nodes which are at the edge of the broadcast domain as the next jump to broadcast the discovery information. This improvement reduces the broadcast nodes and thus reduces the energy of the network. In the synchronization phase, firstly, the two-way time synchronization models is modified, and then collect some samples to estimate the clock offset and clock skew by least square algorithm. This improvement increases the accuracy of the time synchronization.In this paper, the improved algorithm is simulated and verified by Matlab and ZibBee hardware platform based ARM&Linux. The result shows that the improved algorithm increases the accuracy of the time synchronization and extends the period of the time synchronization obviously.