Large Category Query Protocol For Missing Tags In Multi-Category RFID Systems

As one of the key technologies of the Internet of Things,RFID has been widely used in areas such as inventory management,object tracking and intelligent logistics.In recent years,multi-category RFID systems have attracted widespread attention from industry and academia.Although there are thousands of categories in a multi-category RFID system,in some applications,only a portion of the category information needs to be collected.For example,managers need to frequently check the categories of lost items in the warehouse to determine which items are often lost,so as to take effective remedial measures to stop the loss in time and improve the efficiency of inventory management.Existing protocols are not very time efficient in solving the problem of large categories of missing tags queries.In this paper,we propose a protocol MLQ that can quickly query the large categories of missing tags.The protocol includes an allocation phase,a filtering phase and an estimation phase.In the allocation phase,we use k hash functions to allocate each category to a different slot,thereby reducing collisions and improving slot utilization.In the filtering phase,the reader roughly estimates the number of missing tags in each category that has been allocated,filters out the category with the number of missing tags less than the lower bound of the threshold,and stores the category with the number of missing tags greater than the upper bound of the threshold into the set Q,thus greatly reduce the number of tags in the third phase.In the estimation phase,we use the existing TBC protocol to accurately estimate the number of missing tags in each remaining category,and compare with the threshold to find out the large category of missing tags.In addition,this paper optimizes the number of hash functions k and the number of execution rounds w through theoretical analysis.In the experimental part,we compare the time performance and query accuracy of MLQ with other protocols through a large number of simulation experiments.Experiments prove that the MLQ protocol is superior to other protocols in terms of time performance,and the query accuracy is basically close to other protocols.