Research On Time Synchronization Optimization Algorithm For Wireless Sensor Network

In recent years, as information technology, built-in technology and sensor technology developed and maturated rapidly, and the miniature, low cost and low power consuming techniques improved considerably, the distributed large scale wireless sensor network has been developing greatly. Wireless sensor network is a newly emerging information collecting and processing technique. It mainly consists of sensors, microprocessor, and wireless communication interface, and it is a network that integrates data acquisition, fusion processing and communication. It is applied in a variety of areas, such as the defense military, medicine and health, environmental monitoring, family care, disaster rescue and space exploration, etc. It has drawn great attention in field of academic and industry, and become the international focus of research. Compared with the traditional wireless network, wireless sensor networks have obviously different research objective, technical indicators and application requirements.As an important technique in wireless sensor network applications, time synchronization technology plays an essential part in research and application of wireless sensor network, and is needed in most part of wireless sensor networks, for example:in a sensor data fusion technology time synchronization is used to identify the time when events happen in the physical world. However, in wireless sensor networks, accuracy and precision is demanded more strictly than in traditional network. Considering energy requirements restriction, traditional time synchronization method NTP and GPS are not suitable for sensor networks for the matter of complexity, energy issues, price and size. Therefore, considering cost, energy, and volume limitation on network sensors, the time synchronization algorithm for can not meet requirements of wireless sensor network. The existing wireless sensor network synchronization techniques encountered unprecedented challenges, thus research for new time synchronization method suitable for sensor network has become the focus of domestic and foreign research of existing sensor network research.Based on previous studies, this paper discusses why the existing network time synchronization protocol does not apply to sensor network and analyses advantages and disadvantages of several time synchronization protocols for existing sensor networks. It mainly analyses the time-synchronized information transmission method used in RBS time synchronization protocol and the specific principle of how to reduce the time synchronization error. Then it makes further investigation on time synchronization technique of wireless sensor network, including the necessity of its time synchronization algorithm, synchronous technology and its classification, system clock synchronization model, as well as the comparison of various synchronization mechanisms. Finally it optimizes and improves RBS (reference radio synchronous algorithm), a typical time synchronization algorithm. Mainly aiming at the relatively unstableness of node clock, and the synchronization error caused by the delay of message exchanges between nodes, the optimized algorithm synchronization uses theories related to Bayesian estimation to reduce time synchronization error. In the network environment of multiple hops, this algorithm is distinctly more accurate than RBS algorithm. This paper also thoroughly studies the safety of the optimized algorithm. To sum up, from the simulation results we can draw the conclusion that the algorithm improves time synchronization accuracy of wireless sensor network to a certain extent, and it is highly reliable.