The Research Of Device-Free Perception Based On Wireless Sensor Networks

The emergence of wireless sensor network (WSN) technology changes the concept of perception and gathering of information completely, and it combines a variety of modern new technology, such as sensor technology and wireless communication technology, and all the sensor nodes collaborate in real-time and complete to monitor and control the object and environment. As the basic function of the Internet of Things, sensing technology is the way of "comprehensive perception" of the information of Internet of Things. As the rising of the research of Internet of Things, the perception of the wireless sensor network as the core technology research will heat up quickly, and the research of device-free perception has great academic value and application value.Wireless sensor network (WSN) device-free perception, as the name implies, is that WSN takes advantage of the attenuation effect of people or objects(people or objects do not carry any electronic tag or WIF1module, GPS module and other electronic equipment that can communicate with sensor node) on wireless RF signal, and perceive in real time people or objects that appear in wireless environment accurately. The traditional perception system based on security applications, such as infrared sensing system, video monitoring system and microwave probe security system, infrared light can not penetrate smoke and colored objects, camera can not be able to pass through opaque objects in video and microwave probe security system can only detect movement of the target, but radio frequency waves can overcome the above difficulties, as museums, archives and other important items protection unit, compared with the infrared sensing system, video monitoring system and microwave probe security system, the application of the technology of wireless sensor network device-free perception can achieve better security results.This thesis is set in the above situation, and know from the research of a large numbers of papers and experiments that when radio frequency waves pass through people or objects, it produces attenuation and scattering effect, so RSS(Received Signal Strength) has a big reduction, this paper proposes a device-free perception algorithm based on wireless sensor network through collecting and processing the affected RSS of every sensor node. Firstly, we build the hardware platform based on Soc chip CC2430. transplant wireless sensor network operating system TinyOS on CC2430, and develop a token ring program based on wireless sensor network by using NesC language; secondly, this paper proposes device-free perception algorithm based RSS, and make simulation and analysis of the performance of device-free perception algorithm by MATLAB, and obtain an ideal result, then, develop a program of device-free perception algorithm on TinyOS by using NesC language, and test the performance in a stable and ideal environment, achieving a good result; finally, we summarize this paper, and make a prospect on the research direction of the technology of device-free perception based on wireless sensor network.