Research On The Location Of Electromagnetic Radiation Source Based On Received Signal Strength

Although the advancement of information technology has promoted the development of wireless positioning technology,the complexity and variety of wireless signal propagation environments still make wireless positioning technology face enormous challenges.On the one hand,due to the increasing concentration of urban buildings,positioning based on line-of-sight(LOS)propagation becomes increasingly rare,whereas non-line-of-sight(NLOS)propagation increases the estimation error of positioning feature parameters,resulting in a significant decrease in positioning accuracy.On the other hand,although positioning methods based on received signal strength(RSS)are widely used in indoor positioning,it was rarely reported in large-scale outdoor areas(especially urban environments)since the signal strength is easily affected by environmental fluctuations.Compared with the commonly used outdoor positioning methods based on time-of-arrival(TOA)and angle-of-arrival(AOA),the positioning method based on RSS neither requires strict synchronization guarantee nor requires a high-cost array antenna.This method will reduces both the difficulty of implementation and the implementation cost.Therefore,the outdoor positioning method based on RSS has become one of the hotspots of wireless positioning research in recent years.Based on the above phenomena and the existing positioning methods,this article mainly uses easily-available signal strength to study the positioning method of electromagnetic radiation sources in outdoor complex environments.The main work and innovations are as follows:Firstly,this paper proposes a signal strength location method based on dynamic parameter adjustment for the problem that the wireless positioning accuracy is not high and the result is unstable in the current mixed environment of LOS and NLOS.This method adopts the mixture Gaussian model to describe the LOS and NLOS propagation effects,respectively,which can avoid the LOS/NLOS identifying problem,at the same time,this method utilizes the dynamic expectation maximum estimation method to adjust model parameters in real time to adapt to the time-varying characteristics of the environment.Furthermore,a method for selecting measuring points based on geometric dilution of precision(GDOP)is proposed to consider the influence of geometric relation of measuring points on positioning accuracy.Secondly,since the positioning method described above requires a known transmit power,and the target transmit power is often unknown in practical applications.In order to remedy this defect,this paper proposes a three-dimensional RSS positioning method based on semidefinite programming(SDP).This method not only adopts a way of differential RSS to overcome the limitations of needing known transmit power,but also can realizes three-dimensional spatial RSS positioning instead of two-dimensional plane positioning.Finally,the performance of the proposed algorithm is verified by simulation and experimental data.Thirdly,considering the disadvantages of RSS information that is easily affected by the environment,this paper further proposes an RSS/AOA hybrid positioning method that uses angle information to help improving the positioning performance.The method first uses compressed sensing to estimate the arrival angle of the signal,and then uses the mixture of angle and intensity information to evaluate the relation between each measurement point and the target point.Finally,the second-order cone programming(SOCP)algorithm was used for compute the position coordinates of the target point.The simulation results show that the method proposed in this article can obtain higher positioning accuracy compared to use single RSS information.Finally,this paper summarizes the full text,lists the innovation points and deficiencies,and proposes future research directions and emphasis.