Design And Implementation Of RFID Indoor Localization Based On Multipath Perception

In recent years,indoor localization technology is widely used in asset management,logistics management,mobile payment and other fields.It has injected new vitality into the development of various industries.Radio frequency identification(RFID)tags are passive,cheap and easy to deploy.Therefore,how to achieve high-precision indoor localization with RFID tags has attracted wide attention from academia and industry.It is well-known that how to distinguish and suppress the multipath signals is the key to improve localization accuracy.The work done in this paper mainly includes the following aspects:1.We review the state-of-the-art and trend of the indoor localization technology at home and abroad.We also summarize the models and methods of the localization technology with RFID tags.The deficiencies of them are also specified.Based on this,we approach our research idea.2.Using the off-the-shelf RFID products,we build the experiment platform.We analyze the main factors affecting the phase measurements of the RFID signals,which includes system factor,tag direction,and tag coupling.In the practical system,we measure the deviation of the theoretically linear relationship between the distance and phase,providing a priori knowledge support for the design of the subsequent localization algorithm.3.Based on the linear relationship between phase and distance(frequency),we proposed an adaptive multipath perceptive localization method.This method can sense the severity of indoor multipath interference,and can filter out some ‘more ideal' reference positions.Furthermore,we use modified hologram method to improve the localization accuracy.4.In order to verify the effect of the proposed method,in a typical indoor scene,we design a prototype system to accurately locate RFID tags.Experimental results show that the localization error of the system is reduced as compared with some existing works.In particular,when the multipath interference is serious,we can also obtain high localization accuracy.The research results in this paper can overcome the position error and failure caused by the multipath interference.Moreover,the proposed method has advantages of easy deployment,low cost and strong expansibility.In the field of indoor localization,it has certain application value.