位屏蔽多叉树搜索射频识别防碰撞算法

针对RFID树型防碰撞算法中时隙数多、数据通行量大等问题,提出了一种改进的多叉树防碰撞算法,阅读器准确检测碰撞位并向标签反馈碰撞位信息,标签对阅读器已知的ID位进行屏蔽,把ID号转换成连续碰撞的序列号.阅读器利用屏蔽位信息和标签返回的碰撞位编码信息,对标签进行分层分类搜索.通过对标签ID进行屏蔽,阅读器和标签间仅发送对方不知道的碰撞位信息.该算法减少了碰撞时隙和识别时隙,避免了空闲时隙,减少了阅读器和标签间的数据通信量.理论分析和仿真结果表明,该算法减少了系统的时隙总数和数据通信量,提高了阅读器的识别效率.     

一种改进的RFID防碰撞算法

在RFID系统中,当多个标签同时处在阅读器的读写范围内时,如果没有相应的防冲突机制,会导致标签到阅读器的通信冲突,使得从标签返吲的数据难以被阅读器正确识别.防冲突算法是阅读器快速、正确获取标签数据的关键.详细论述了射频识别技术中的关键问题:防碰撞技术,提出了一种基于二进制防碰撞算法的改进树形算法.在介绍Manchester编码原理的基础上,对该改进算法的命令、原理进行了较为系统的论述,经验证该算法提高了阅读器辨认标签的速度,辨认准确性也大大提高,在电子标签数量较大的情况下比传统的二进制及动态二进制防碰撞算法优势更加明显.     

一种基于碰撞位指示的射频识别标签防碰撞算法

多标签碰撞是射频识别(RFID)技术在推广应用中必须克服的一个问题。针对目前RFID标签防碰撞算法存在识别效率低的不足,该文提出一种基于碰撞位指示的RFID标签防碰撞的碰撞位指示算法(CBIA)。通过跟踪待识别标签的碰撞位,采用碰撞位编解码技术,对待识别标签进行重复分组,直到所有标签都被正确识别。算法通过确定性分组,避免了空闲时隙的产生。仿真结果表明,采用CBIA算法的多标签识别系统,吞吐率可以达到每时隙0.7个标签,CBIA算法识别效率优于优化查询跟踪树算法(OQTT)和碰撞跟踪树算法(CTTA)算法。     

一种减少通信复杂度的RFID搜索树防碰撞算法

针对射频识别搜索树防碰撞算法中通信数据量大、识别时延长等问题,提出了一种减少通信复杂度的防碰撞算法.在标签中引入前缀长度寄存器和响应标志寄存器,在阅读器堆栈区存储前缀个数信息,阅读器通过发送前缀长度信息,对标签进行分类搜索,阅读器和标签不再发送对方已经识别的序列号,有效减少了通信数据量.仿真结果表明,与传统的二叉树搜索防碰撞算法相比,该算法可明显减少系统通信复杂度,提高标签的搜索速率.     

基于后退式索引二进制树形搜索的RFID防碰撞算法

在分析目前针对标签防碰撞问题采用的防碰撞算法优缺点的基础上,利用后退式索引二进制树形搜索算法的基本原理,设计了一种RFID标签防碰撞算法.该算法充分利用碰撞节点的信息,采取调整策略,能有效减少数据的传送量,快速高效地识别RFID标签.对该算法进行了仿真分析,结果表明,该算法的执行效率达到50％以上.     

基于位判别的后退式搜索防碰撞算法

在射频识别(RFID)系统中,经常出现多个标签同时向阅读器传递信息,进而相互干扰导致阅读器无法正确识别标签的碰撞现象。针对这一问题,提出了一种基于位判别的后退式二进制搜索防碰撞算法。该算法在传统后退式二进制搜索算法的基础上进行了改进,提出了碰撞距离的概念,通过对碰撞距离的判别来确定搜索的方式。实验结果表明,改进算法的性能比其他几种算法有所提高,传送数据量降低了很多。该算法可以有效的减少传输数据量,提高识别速率。     

射频识别系统的防碰撞算法研究

电子标签防碰撞是RFID系统中一个关键问题.在射频识别系统中,当阅读器作用范围内有多个标签同时向阅读器发送数据时,会产生冲突,必须采用一种防碰撞算法解决这种冲突.在分析典型的二进制及动态二进制防碰撞算法基础上,采用了一种新的防碰撞算法.经实验证明,该算法能有效解决射频识别系统中多目标识别的防碰撞问题.     

基于二叉树的RFID防碰撞算法的研究

在二叉树算法的基础上提出了锁位后退防碰撞(BLBO)算法,增加了锁位寻呼指令,阅读器根据译码结果判断发生碰撞的比特,发送锁位寻呼指令锁定发生碰撞的比特,寻呼过程采用后退策略,每次识别一个标签之后返回到上一个发生碰撞的节点.算法充分考虑了阅读器寻呼次数、传输时延、标签能耗以及吞吐量4个重要性能指标,仿真结果表明,BLBO防碰撞算法较其他二叉树算法性能有明显提高,更适用于RFID防碰撞协议.     

改进型帧时隙ALOHA防碰撞算法研究

为进一步提高RFID系统中电子标签防碰撞算法的识别效率,对帧时隙ALOHA防碰撞算法的性能进行分析,提出一种结合精确标签估计和二进制搜索的改进型帧时隙ALOHA算法.将识别过程分为标签估计和标签识别两个阶段,在标签估计算法中引入碰撞概率上、下限参数,并精确估计标签数量对初始帧时隙大小进行优化;在标签识别阶段,利用二进制搜索算法对时隙内的碰撞标签进行快速识别.通过对识别过程进行仿真结果表明:改进的算法改善了防碰撞性能,提高了RFID系统的标签识别效率.     

计数型位屏蔽射频识别防碰撞算法设计

提出了一种新的二进制搜索防碰撞算法。通过在标签中设置屏蔽寄存器,对阅 读器已知的数据比特位进行屏蔽,标签仅返回阅读器不知道的冲突位信息,可以有效减小阅 读器和标签之间相互传送的数据比特数;通过在标签中设置休眠计数器,减小了搜索标签的 总次数,进一步减小了阅读器发送的数据比特数。该方法有效提高了阅读器识别标签的速率 。     

基于模运算标签分类的RFID标签防碰撞识别方法

为了解决射频识别(RFID)系统中的多标签防碰撞问题,在分析帧时隙ALOHA算法的基础上,提出一种基于模运算标签分类的RFID标签防碰撞识别方法。引入一种检测信息碰撞的时隙选择信息,对标签所选取时隙的碰撞情况进行分析并估计标签数量;然后对标签EPC编码进行逐级的取模运算,将同余的标签归为一组。各个标签经过K次取模运算后,分为2k组,每组只有发生少量碰撞位的标签。再将标签按照分组对应的时隙发送,碰撞标签采用二叉树后退式算法处理。本方法极大的提高了标签的识别效率,适用于射频识别系统中阅读器对于大量电子标签的快速识别。     

A new anti‐collision protocol based on information of collided tags in RFID systems

Radio frequency identification (RFID) technology has recently become an integral part of a wide range of applications. One of the challenges in RFID systems is the tag anti‐collision issue, for which several anti‐collision tag identification protocols have been proposed. This paper proposes a novel slotted ALOHA‐based RFID tag anti‐collision algorithm which can be employed for tag identification. The main idea of this algorithm is to use the information available in collision slots, called collided data, to identify tags uniquely. For this purpose, the collision slots that include only two tags are selected. Then, the non‐conflict bits in these slots are used to possibly identifying the tags. Because in the proposed algorithm readers use both single slots and also the collision slots for tag identification, the performance is increased significantly compared with other protocols. Results of the study indicate that in the proposed algorithm, the optimal frame size for an individual tag number is equal to the half of tags number and the efficiency of the proposed protocol is improved to about 73%. Copyright © 2015 John Wiley & Sons, Ltd.     

Adaptive Binary Splitting: A RFID Tag Collision Arbitration Protocol for Tag Identification

In the RFID system, a reader recognizes tags through communications over a shared wireless channel. When multiple tags transmit their IDs at the same time, the tag-to-reader signals lead to collision. Tag collision arbitration for passive RFID tags is significant for fast identification since collisions disturb the reader's identification process. This paper presents an Adaptive Binary Splitting (ABS) protocol which is an improvement on the binary tree protocol. To reduce collisions and identify tags efficiently, ABS uses information which is obtained from the last processes of tag identification. Our performance evaluation shows that ABS outperforms other tree based tag anti-collision protocols. This work was supported by Korea Research Foundation Grant (KRF-2005-041-D00680).     

基于CDMA技术的新型防碰撞算法

标签碰撞是射频识别（RFID）技术的常见问题,该问题影响了RFID系统通信过程中数据传输的完整性.在分析已有防碰撞方法的基础上,根据帧时隙分组ALOHA算法,结合码分多址技术,提出了新型的标签防碰撞算法.该算法能够有效减小标签之间的碰撞概率,缩短读写器操作时间,提高吞吐率,很适合应用于具有较大数量标签的RFID系统中.     

Novel tag estimation method by use of Manchester coding in RFID systems

Radio frequency identification suffers from tag collision issue. ALOHA‐based algorithms are useful and practical groups of tag anti‐collision algorithm among others. Some standards such as EPCglobal Class‐1 Generation‐2 use some kind of dynamic framed slotted ALOHA (DFSA) to cope with tag collision. DFSA efficiency depends on estimating the number of unidentified tags in each identification cycle accurately. So tag estimation is one of the challenging issues in DFSA. In this paper, we use Manchester coding to compute the lower bound of collided tags in a frame and then add α as an additional value to computed value according to the difference between optimal number of collision slots and calculated number of collision slots. Then, we evaluate and compare our method with other proposed methods.     

Optimal Dynamic Framed Slotted ALOHA Based Anti-collision Algorithm for RFID Systems

In Radio Frequency IDentification (RFID) system, one of the most important issues that affect the data integrity is the collision resolution between the tags when these tags transmit their data to reader. In majority of tag anti-collision algorithm, Dynamic Framed Slotted Aloha (DFSA) has been employed as a popular collision resolution algorithm to share the medium when multiple tags respond to the reader’s signal command. According to previous works, the performance of DFSA algorithm is optimal when the frame size equals to the number of un-identified tags inside the interrogation zone. However, based on our research results, when the frame size equals to number of tags, collision occurs frequently, and this severely affects the system performance because it causes power consumption and longer tag reading time. Since the proper choice of the frame size has a great influence on overall system performance, in this paper we develop an analytical model to study the system throughput of DFSA based RFID systems, and then we use this model to search for an optimal frame size that maximizes the system throughput based on current number of un-identified tags. In addition to theoretical analysis, simulations are conducted to evaluate its performance. Comparing with the traditional DFSA anti-collision algorithm, the simulation results show that the proposed scheme reaches better performance with respect to the tag collision probability and tag reading time.     

Gen2‐Based Tag Anti‐collision Algorithms Using Chebyshev's Inequality and Adjustable Frame Size

Arbitration of tag collision is a significant issue for fast tag identification in RFID systems. A good tag anti‐collision algorithm can reduce collisions and increase the efficiency of tag identification. EPCglobal Generation‐2 (Gen2) for passive RFID systems uses probabilistic slotted ALOHA with a Q algorithm, which is a kind of dynamic framed slotted ALOHA (DFSA), as the tag anti‐collision algorithm. In this paper, we analyze the performance of the Q algorithm used in Gen2, and analyze the methods for estimating the number of slots and tags for DFSA. To increase the efficiency of tag identification, we propose new tag anti‐collision algorithms, namely, Chebyshev's inequality, fixed adjustable framed Q, adaptive adjustable framed Q, and hybrid Q. The simulation results show that all the proposed algorithms outperform the conventional Q algorithm used in Gen2. Of all the proposed algorithms, AAFQ provides the best performance in terms of identification time and collision ratio and maximizes throughput and system efficiency. However, there is a tradeoff of complexity and performance between the CHI and AAFQ algorithms.     

An improved anti‐collision protocol for radio frequency identification tag

Many anti‐collision protocols have been proposed at present. Almost all known protocols exhibit an overall identification efficiency smaller than 50%. And all of them are proposed for general purpose applications and do not consider the distribution characteristic of tag IDs in different radio frequency identification (RFID) systems. In real world, there are many RFID systems, in which the tag IDs are mostly distributed continuously, such as in container terminals, warehouse management, supply chain management, and so on. This paper presents an efficient anti‐collision protocol, named improved collision tree protocol (ICT), to identify RFID tags simultaneously. The main novelties of this paper include that the duality and certainty principle is introduced and used in ICT to improve the tag identification efficiency, and the continuous and partially continuous distributions of tag IDs are taken into account in this paper. Both the theoretical and experimental results indicate that ICT improves the tag identification efficiency up to 100% when the tag IDs are distributed continuously, and always above 50% even when the tag IDs are distributed uniformly. For straightforward and efficient, ICT can be used in various RFID tag identification conditions, especially when the tag IDs are distributed continuously or partially continuously. Copyright © 2013 John Wiley & Sons, Ltd.     

可并行识别的分组动态帧时隙ALOHA标签防碰撞算法

该文针对现有动态帧时隙ALOHA标签防碰撞算法的系统吞吐率低、算法效率低等问题,提出一种可并行识别的分组动态帧时隙ALOHA(PIGDFSA)标签防碰撞算法。该文以实验为基础,探索了待识别标签数、标签分组数、帧长对系统吞吐率与标签碰撞率的影响,研究了提升系统吞吐率与降低标签碰撞率的策略与方法。结合射频识别(RFID)的多天线系统,引入FastICA技术,从而实现碰撞时隙重新定义,并以此为基础,利用未识别标签数目自适应确定分组数与帧长。仿真结果表明:PIGDFSA算法在标签数达到2000时,算法吞吐率仍能稳定在92%以上,与FSA-256, GDFSA, BSDBG等算法相比具有更高的算法吞吐率,更少的空隙时隙,更高的算法效率。