The Research Of Localization Technology Based On TOF Ranging In Wireless Sensor Network

The Wireless Sensor Networks (WSN) as the most up and coming information collection technology, has widely used in many industries and our daily lives in the modern digital society. The information of nodes location is an essential requirement for many WSN applications. Without location information of sensor nodes, the sensed data or the detection of events is meaningless. Node localization technology is one of the most challenging and important issues in WSN. Because of the investigation of the present algorithms which have many shortcomings, such as complicated calculations, high energy-consuming and low precision, two novel localization algorithms are proposed in this paper based on time of flight (TOF) ranging.This paper puts forward a novel and high accuracy algorithm by combining distance-measuring with angle-measuring. This paper first discovered the range shift phenomenon of TOF ranging through researching many experimental results. Meanwhile an online modeling method is presented to obtain the offset and compensate distance error. In addition, the paper also proposed a new weighted curve fitting method based on Least Square principle to calculate the orientation. The experiment results show that the precision of ranging and angle measurement reaches 0.83m and 1.65° respectively. The location accuracy is as high as 3.94%.Through the massive experimental and simulation results, the paper uncovers the latent vulnerability of the classical trilateral algorithm that is the localization error can be considerable despite the high precision of the measured distance. Based on the analysis and theoretical derivation, we found that the ill matrix generated by the three anchor nodes allocation led to the gross localization error. So that a localization algorithm based-on the orthogonal degree of matrices is proposed. The simulation and experiment results show that the proposed algorithm can retain good localization accuracy with the presence of outliers. Compared to the traditional trilateral algorithm, in case of good anchor layout, the localization accuracy is improved by about 4.95%, while in bad anchor layout, the localization accuracy is improved as high as 56.12%.