Research On Dynamic Tag Estimation And Search Technology In Large-Scale RFID System

With the development of the Internet of Things technology,RFID as its key technology has been widely concerned and applied.In the application of goods management such as logistics and warehouse management,the managed goods inevitably need to be moved frequently.The movement of goods will cause inventory changes and increase the difficulty of management.An important problem in applying RFID to these fields is how to monitor the tags in the system in a dynamic and complex environment,so as to achieve efficient management of goods.This paper focuses on two types of tag monitoring problems: dynamic tag estimation and tag search.The main contributions are summarized as follows:Aiming at the problem of dynamic tag estimation,we design a novel method called Time Slot Reuse(TSR)that estimates the number of two tags simultaneously through generates two logical frames from only one physical frame.Based on TSR,we propose a protocol called SSR that can accurately estimate the numb er of dynamic tags by using the generated logic frames.However,the performance of SSR degrades significantly when the disparity between the number of the two types of tags is remarkable.We further propose an enhanced version of SSR(ESSR),which overcomes this drawback by partitioning the frame into ranges and mapping different types of tags into different ranges.Rigorous theoretical analysis is performed to tune parameters in SSR and ESSR to minimize the execution time.Extensive simulation results show that the protocol proposed can achieve the specified accuracy requirements and improve the estimation efficiency compared with the existing protocol.Aiming at the problem of tag search,we propose an efficient tag search protocol(TSK)based on KEY value.TSK achieves an accurate search result without false positives.It can not only effectively utilize collision signals,thereby avoiding the waste of time slots.Furthermore,it can infer unverified tag status through combine the information received in each time slot,further speeding up the search process.However,we observe that when the proportion of target tags to system tags is small,TSK wastes a lot of time verifying interference tags.Therefore,we further propose the Enhanced TSK(ETSK)protocol.ETSK filters out the interference tags in the system through the instruction vector,thereby improving the search efficiency.Finally,we set the optimal parameters to maximize the performance of the proposed protocol through rigorous theoretical analysis.Extensive experimental results show that,our best protocol effectively reduces the search time compared to the existing search protocol.