Research And Application Of RFID Anti-collision Algorithm Coping With Capture Effect

As one of the core technologies of Internet of Things,Radio Frequency Identification(RFID)technology is expanding its application market with the popularity of the Internet of Things.Readers and tags are important parts of the RFID system,the reader is responsible for emitting the query command,the tags is responsible for responding to the command.When multiple tags send response commands to the same reader at the same time,a tag collision problem occurs;There are new arrival tags may cause some tags to be unrecognized,that is,tags leakage problem.Existing research mainly focuses on solving the problem of tag collisions in static environment.The so-called static environment is an environment in which the number of tags is fixed within a reader's sensing range.However,in a non-static environment,the existing methods are difficult to adapt to changing environment,leading to more serious tag leakage problems.In addition,the existing methods seldom consider the effects of the capture effect,so the recognition performance obtained by them can not objectively evaluate the recognition efficiency of their prototype system.In this paper,we propose an anti-collision algorithm based on dynamic environment in the frame reservation mechanism from two aspects:capture effect and the estimation of tag number.This thesis has carried on a series of research work,the corresponding research conclusion is as follows:(1)In view of the simplified factor considered in the existing RFID capture effect,the RFIDCapture effect model is proposed dependence on some factors,like radiation pattern of antennas,indoor wireless channel,backscattering ratio of tags and spatial distribution of tags.Simulation and analysis draw different factors on the capture effect of the degree of impact for the later anti-collision algorithm to do some research preparatory work.(2)Aiming at the problem of tag leakage caused by the newly arrived tag group in dynamic environment,a tag arrival model is constructed in dynamic environment.The recognition process model uses Poisson process accumulation principle and optimization algorithm to determine the frame length,and achieves the goal of improving the recognition rate.In addition,the theoretical knowledge of stochastic processes proves the maximum value(0.386)of tag arrival rate under the requirement of smooth running of the algorithm,which provides theoretical evidence for the smooth operation of the system.(3)A collision avoidance algorithm RDFSA(Reservation Dynamic Frame Slotted ALOHA,RDFSA)based on reservation mechanism is proposed after analysing the capture effect on the reservation and read process.The simulation obtain the optimal parameters of the algorithm under the effect of capture.The performance analysis proves that the recognition efficiency of this algorithm is obviously improved compared with the existing anti-collision algorithm,and the recognition efficiency is as high as 91.6%.