| Wireless Sensor Network(WSN) always consists of microprocessor, sensors and wireless communication and can be used for data collecting and fusion. With increasing developed communication technology, sensor technology and embedded theory, WSN has been used in many fields and shows great prospect such as environment inspecting, house daily affairs, national defense and military, disaster rescue and medical treatment. WSN has become a great concern in the field of the international academic community and industry.There are many technology problems in WSN. Time synchronization is among them and is of critical importance. Traditional network synchronization methods such as NTP and GPS have a limitation in complexity, energy consumption, costs and size thus it is not proper for wireless sensor network. Sensors in WSN has the limitation of cost, energy and size which brings many challenges for the time synchronization of WSN. Working out a time synchronization method which fits wireless sensor network well becomes a common concern in the world.This paper starts with introducing the basic theory of wireless sensor network such as the system frame and application fields. The paper then gives the conception and necessity of time synchronization as well as the performance estimation standard and challenges. Several classic time synchronization algorithms are introduced and analyzed between their advantages and shortcomings after that. Based on the existing time synchronization algorithms, this paper proposes an improved algorithm which divides the network into clusters to save energy consumption and make timestamps in MAC to improve the accuracy of time synchronization. NS2 simulation shows that the improved algorithm has better accuracy performance and low network overcome. At last, the paper builds the hardware platform and also demonstrates the energy performance showed in the software simulation. In the end of this passage, there gives the next research direction. |
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