A Physical Layer Network Coding Based Tag Anti-Collision Algorithm for RFID System

In RFID(Radio Frequency IDentification)system,when multiple tags are in the operating range of one reader and send their information to the reader simultaneously,the signals of these tags are superimposed in the air,which results in a collision and leads to the degrading of tags identifying efficiency.To improve the multiple tags’identifying efficiency due to collision,a physical layer network coding based binary search tree algorithm(PNBA)is proposed in this paper.PNBA pushes the conflicting signal information of multiple tags into a stack,which is discarded by the traditional anti-collision algorithm.In addition,physical layer network coding is exploited by PNBA to obtain unread tag information through the decoding operation of physical layer network coding using the conflicting information in the stack.Therefore,PNBA reduces the number of interactions between reader and tags,and improves the tags identification efficiency.Theoretical analysis and simulation results using MATLAB demonstrate that PNBA reduces the number of readings,and improve RFID identification efficiency.Especially,when the number of tags to be identified is 100,the average needed reading number of PNBA is 83%lower than the basic binary search tree algorithm,43%lower than reverse binary search tree algorithm,and its reading efficiency reaches 0.93.

A Physical Layer Algorithm for Estimation of Number of Tags in UHF RFID Anti-Collision Design

A priori knowledge of the number of tags is crucial for anti-collision protocols in slotted UHF RFID systems.The number of tags is used to decide optimal frame length in dynamic frame slotted ALOHA(DFSA)and to adjust access probability in random access protocols.Conventional researches estimate the number of tags in MAC layer based on statistics of empty slots,collided slots and successful slots.Usually,a collision detection algorithm is employed to determine types of time slots.Only three types are distinguished because of lack of ability to detect the number of tags in single time slot.In this paper,a physical layer algorithm is proposed to detect the number of tags in a collided slot.Mean shift algorithm is utilized,and some properties of backscatter signals are investigated.Simulation results verify the effectiveness of the proposed solution in terms of low estimation error with a high SNR range,outperforming the existing MAC layer approaches.

A Frame Breaking Based Hybrid Algorithm for UHF RFIDAnti-Collision

Multi-tag collision imposes a vital detrimental effect on reading performanceof an RFID system. In order to ameliorate such collision problem and to improve thereading performance, this paper proposes an efficient tag identification algorithm termedas the Enhanced Adaptive Tree Slotted Aloha (EATSA). The key novelty of EATSA is toidentify the tags using grouping strategy. Specifically, the whole tag set is divided intogroups by a frame of size F. In cases multiple tags fall into a group, the tags of the groupare recognized by the improved binary splitting (IBS) method whereas the rest tags arewaiting in the pipeline. In addition, an early observation mechanism is introduced toupdate the frame size to an optimum value fitting the number of tags. Theoretical analysisand simulation results show that the system throughput of our proposed algorithm canreach as much as 0.46, outperforming the prior Aloha-based protocols.

An Adaptive Tag Anti-Collision Protocol in RFID Wireless Systems

A novel anti-collision algorithm in RFID wireless network is proposed.As it is put forward on the basis of collision tree(CT)and improved collision tree(lCT) anti-collision protocols,we call it adaptive collision tree protocol(ACT).The main novelty of this paper is that the AD strategy is introduced and used in ACT to decrease collisions and improve the tag system throughput.AD strategy means that query strings will divide into two or four branches adaptively according to the label quantity.This scheme can decrease both depth of query and collision timeslots,and avoid producing too much idle timeslots at the same time.Both theoretical analysis and simulation results indicate that the novel proposed anticollision protocol ACT outperforms the previous CT and ICT protocols in term of time complexity,system throughput,and communication complexity.

An Improved Binary Search Anti-Collision Protocol for RFID Tag Identification

Radio frequency identification(RFID)has been widespread used in massive items tagged domains.However,tag collision increases both time and energy consumption of RFID network.Tag collision can seriously affect the success of tag identification.An efficient anti-collision protocol is very crucially in RFID system.In this paper,an improved binary search anti-collision protocol namely BRTP is proposed to cope with the tag collision concern,which introduces a Bi-response mechanism.In Bi-response mechanism,two groups of tags allowed to reply to the reader in the same slot.According to Bi-response mechanism,the BRTP strengthens the tag identification of RFID network by reducing the total number of queries and exchanged messages between the reader and tags.Both theoretical analysis and numerical results verify the effectiveness of the proposed BRTP in various performance metrics including the number of total slots,system efficiency,communication complexity and total identification time.The BRTP is suitable to be applied in passive RFID systems.

Performance Analysis of RFID Framed Slotted Aloha Anti-Collision Protocol

In this paper, we develop a novel mathematical model to estimate the probability distribution function of the number of tags discovered after a certain number of interrogation rounds. In addition, the pdfs of the number of rounds needed to discover all the tags are also calculated. The estimation of such pdfs will be helpful in estimating the number of interrogation rounds and the optimal parameter configuration of the RFID system which in turn will be helpful in estimating the time needed to discover all tags. Our results show that the proposed model accurately predicts the tags detection probability. We then use the proposed model to optimally configure the reader parameters (i.e. the frame size and the number of interrogation rounds).

A Dynamic Multi-ary Query Tree Protocol for Passive RFID Anti-collision

In this paper,a dynamic multi-ary query tree(DMQT)anti-collision protocol for Radio Frequency Identification(RFID)systems is proposed for large scale passive RFID tag identification.The proposed DMQT protocol is based on an iterative process between the reader and tags which identifies the position of collision bits through map commands and dynamically encodes them to optimize slots allocation through query commands.In this way,the DMQT completely eliminates empty slots and greatly reduces collision slots,which in turn reduces the identification time and energy costs.In addition and differently to other known protocols,the DMQT does not need to estimate the number of tags,reducing the protocol implementation complexity and eliminating the uncertainty caused by the estimation algorithm.A numerical analysis shows that DMQT has better performance than other algorithms for a number of tags larger than 300.Meanwhile,when the number of tags is 2000 and the tag identity(ID)length is 128 bits,the total identification time is 2.58 s and the average energy cost for a tag identification is 1.2 mJ,which are 16.9%and 10.4%less than those of state-of-the-art algorithms,respectively.In addition,a DMQT extension based on ACK command has also been presented to deal with capture effect and avoid missing identification.

Synchronous Dynamic Adjusting: An Anti-Collision Algorithm for an RF-UCard System

An RF-UCard system is a contactless smartcard system with multiple chip operating systems and multiple applications. A multi-card collision occurs when more than one card within the reader’s read field and thus lowers the efficiency of the system. This paper presents a novel and enhanced algorithm to solve the multi-card collision problems in an RF-UCard system. The algorithm was originally inspired from framed ALOHA-based anti-collision algorithms applied in RFID systems. To maximize the system efficiency, a synchronous dynamic adjusting (SDA) scheme that adjusts both the frame size in the reader and the response probability in cards is developed and evaluated. Based on some mathematical results derived from the Poisson process and the occupancy problem, the algorithm takes the estimated card quantity and the new arriving cards in the current read cycle into consideration to adjust the frame size for the next read cycle. Also it changes the card response probability according to the request commands sent from the reader. Simulation results show that SDA outperforms other ALOHA-based anti-collision algorithms applied in RFID systems.

Research on RFID Anti-Collision in Multi-label Environment

This paper introduces several common binary tree anti-collision algorithms. They are binary tree algorithm, dynamic binary tree algorithm, and backward binary tree algorithm. Then, based on these algorithms, an improved binary tree algorithm is proposed. Simulation and results analysis show that the improved binary anti-collision algorithm has higher performance than other binary tree algorithms, and improves the efficiency of RFID card reader searching card in multi-label environment.

Research on Anti-collision Algorithm of Short Distance Data communication based on Binary-Tree Disassembly

This paper puts forward adaptive anti collision algorithm based on two fork tree decomposition. New search algorithm built on the basis of binary-tree algorithm, using the uniqueness of the label EPC, to estimate the distribution of label by slot allocation, the huge and complicated two fork tree is decomposed into several simple binary-tree by search the collision slots for binary-tree, so, it can simplifies the search process. The algorithm fully considers4 important performance parameters of the reader paging times, transmission delay, energy consumption and throughput label, the simulation results show that, the improved anti-collision algorithm is obviously improved performance than other two fork tree algorithm, it is more suitable for RFID anti-collision protocols.

Improved adaptive genetic algorithm based RFID positioning

The existing active tag-based radio frequency identi-fication(RFID)localization techniques show low accuracy in practical applications.To address such problems,we propose a chaotic adaptive genetic algorithm to align the passive tag ar-rays.We use chaotic sequences to generate the intersection points,the weakest single point intersection is used to ensure the convergence accuracy of the algorithm while avoiding the optimization jitter problem.Meanwhile,to avoid the problem of slow convergence and immature convergence of the algorithm caused by the weakening of individual competition at a later stage,we use adaptive rate of change to improve the optimiza-tion efficiency.In addition,to remove signal noise and outliers,we preprocess the data using Gaussian filtering.Experimental results demonstrate that the proposed algorithm achieves high-er localization accuracy and improves the convergence speed.

A collision recovery algorithm using optimal Q parameter based on BIBD in RFID

In this work,an optimal Q algorithm based on a collision recovery scheme is presented. Tags use BIBD-( 16,4,1) codes instead of RN16 s. Therefore,readers can make a valid recognition even in collision slots. A way of getting the optimal slot-count parameter is studied and an optimal Q algorithm is proposed. The theoretical and simulation results show that the proposed algorithm can improve reading efficiency by 100% more than the conventional Q algorithm. Moreover,the proposed scheme changes little to the existing standard. Thus,it is easy to implement and compatible with ISO 18000-6C.

ENHANCED ENERGY-SAVING ANTICOLLISION ALGORITHMS WITH IMPROVING THROUGHPUT FOR RFID SYSTEM

Tag collision algorithm is a key issue for energy saving and throughput with Radio Frequency IDentification (RFID) system more popular in sensing infrastructure of covering wider area on a large scale. Exploiting low energy consumption strategy would enable longer operational life of tags and reader with battery energy supply. And improving throughput is required on a large scale to preserve the capability of the correct reception. Therefore, this paper proposes an enhanced anti-collision algorithm called Dynamic Slotted with Muting (DSM), which uses multiple slots within a frame per node in a binary tree and takes tag estimation function to optimize the number of slots, and adds a mute command to put identified tags silence. The performance of the proposed algorithm is analytically provided, and simulation results show that DSM saves more than 40% energy consumptions both at reader and tags, and improves more than 35% throughput compared to the existing algorithms. Thus our algorithm is demonstrated to perform efficient energy savings at reader and tags with throughput improvement.

基于KNN-XGBOOST堆叠模型在PCB RFID天线阻抗预测的研究

针对传统的天线仿真建模过程中需要的天线阻抗耗时长问题,文中提出一种基于KNN-XGBOOST模型的天线阻抗预测方法。现有研究大多为单一预测算法,旨在通过对比寻求预测效果更优的算法。首先通过ANSYS仿真软件收集大量的PCB RFID天线阻抗设计数据,然后结合影响阻抗中天线长度和频率共8个有效特征,以KNN和XGBOOST两种算法作为基模型,线性回归作为元模型,构建了一个堆叠集成学习模型。在实验过程中,通过交叉验证和网格搜索技术,对模型的超参数进行了精细调优,以确保模型能够达到最优的预测性能。实验结果显示,与单一的KNN和XGBOOST模型相比,KNN-XGBOOST模型的均方根误差降低了30%~70%,R^(2)提高了10%。在预测PCB RFID天线的阻抗实部和虚部时,KNNXGBOOST模型具有较高的准确率和较低的预测误差,证明了其在电磁仿真设计优化中的应用价值。

基于BIM和RFID的物资管理系统设计开发

采用动态帧时隙(DFSA)类算法解决RFID标签信息碰撞的问题,并设计了一种BIM和RFID集成的物资管理系统。通过仿真实验对提出的物资管理系统进行测试,结果表明,BIM和RFID集成的物资管理系统的物资吞吐量在高峰期可达200万件,远大于传统物资管理系统的物资吞吐量,不仅可以实现大流量的仓储物资吞吐,并且单件物资管理成本低于传统的物资管理成本,实现了物资出厂、运输、仓储、使用及转运等数据的信息化管理与数据模型化管理。

基于改进型蛇算法的RFID网络规划部署

针对无线射频识别(RFID)网络规划的优化部署问题,提出一种基于Circle映射的嵌入正弦余弦算法和自适应阈值的改进型蛇算法(ESO)。在种群初始化阶段利用Circle混沌映射的均匀性和遍历性等特点,在局部搜索阶段和开发阶段分别引入正弦余弦算法(SCA)和自适应阈值等算法机制,弥补了蛇算法初始化过程不够均匀、容易陷入局部最优和收敛速度慢等缺点。在满足100%标签覆盖率、减少阅读器之间的碰撞干扰、实现阅读器的负载均衡,以及降低总的发射功率这4个目标的基础上,求解阅读器最佳的部署位置,将所提算法与粒子群算法(PSO)、灰狼算法(GWO)、樽海鞘算法(SSA)进行了对比分析。实验结果表明,改进型蛇算法在对RFID网络进行优化部署时寻优能力更强,对RFID网络部署的综合性能提升明显,在相同的实验条件下,ESO的最佳适应度值比PSO提高了28.1%,比GWO提高了17.7%,比SSA提高了22.9%,可以更有效地得出最优的RFID网络规划部署方案。

基于分组查询树的RFID标签识别算法

为了解决多标签碰撞问题,设计一种新型RFID防碰撞算法。通过在QT防碰撞算法基础研究,针对大量移动标签场景提出了一种分组查询树防碰撞(GQT)算法。新算法通过将标签ID码进行分组的方式进行重新编码,按连续三比特位一组形式进行组合,同组之间前两位做异或或者同或运算,如果异或结果得到的是第三位的值,将这组编号为0,如果同或运算结果为第三位的值,将这组编号为1,交叉进行编号,将生成的编号进行重新编码形成新的二进制比特位,最后采用查询树算法进行识别。理论分析表明GQT算法能消除空闲时隙,仿真结果表明,与QT算法和AHT算法作比较,GQT算法能减少碰撞时隙数,并且在大量标签数的情况下,算法识别效率能保持在0.76左右。可见GQT算法在物流运输、贮存、管理等场景具有良好的应用价值。

基于G_NSGA-Ⅱ算法的RFID网络规划

针对RFID网络中阅读器冲突问题,在NSGA-Ⅱ算法的基础上提出G_NSGA-Ⅱ算法。对RFID网络规划问题进行数学建模,引入全局存档机制存储精英解,保留性能最佳个体;采用精英保留策略的锦标赛选择方法,确保选择出的个体具有较优秀的性能;同时,引入高斯变异算子,以增加种群多样性,从而避免算法陷入局部最优解。仿真结果表明,G_NSGA-Ⅱ算法所产生的解集质量较好,相较于NSGA-Ⅱ、AW_GA和MOEA/D等3种算法,其在解集的分布性和收敛性上具备明显优势,在解决RFID问题上具备有效性和可行性。

基于RFID的无源无线螺栓松动故障定位算法

针对水电机组锥管进人门螺栓松动故障定位问题,提出了基于射频识别(radio frequency identification,RFID)的无源无线水电机组锥管进人门螺栓松动故障定位改进虚拟参考消除(virtual reference elimination,VIRE)算法。首先,确定超高频RFID读写器下所有螺栓松动故障辨识节点内标签的接收信号强度指示(received signal strength indicator,RSSI)值;然后,采用样条插值法插入虚拟标签,计算出虚拟螺栓松动故障辨识节点内标签的RSSI值;最后,采用动态阈值(threshold,Th)使最邻近螺栓松动故障辨识节点内标签数接近最优值,求出待测螺栓松动故障辨识节点内标签的定位坐标并记录,选择几组数据取平均值作为最终结果。结果表明,改进VIRE算法的平均定位误差相对于基于动态有源RFID校准的位置识别(location identification based on dynamic active RFID calibration,LANDMARC)算法、传统VIRE算法分别降低了98.72%、25.27%。该研究成果可以满足复杂环境下的水电机组锥管进人门螺栓松动故障定位需要。

基于卡尔曼滤波和图基平滑的RFID手术工勤人员定位追溯优化方法

以医院手术工勤人员的全流程智慧追溯为建设场景,以改善射频识别(Radio Frequency Identification,RFID)物联网手术工勤人员定位精度低、鲁棒性差问题为研究目标,提出一种基于卡尔曼滤波和图基平滑的室内定位优化方法,增强定位准确性。该研究首先以图的数据结构对场景进行建模,接着基于卡尔曼滤波(Kalman Filtering)和图基平滑(Tukey Smoothing)算法建立RFID室内定位优化方法,最后通过定位优化模块改善手术工勤人员定位追溯的成效。实证分析结果表明:该方法能有效改善定位精度,方法应用的3个月内手术工勤人员追溯准确率为99.75%。