捕获效应下RFID标签的CATPE防冲突协议

在被动式RFID系统中,当多个标签同时向阅读器发射信号时,捕获效应能使阅读器成功接收其中一个标签信号。为提高捕获效应下的识别效率,本文提出一种名为CATPE (capture-aware and tag-population estimation)的RFID标签防冲突协议。该协议可同时估计标签数和捕获效应的发生概率,并在非等长时隙下设置最优帧长。CATPE协议的优点在于不需搜索极值,仅一步计算就能完成估计,从而降低了计算复杂度。计算机仿真显示,该协议与已有协议的识别效率相近,但计算复杂度得到了降低。     

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。     

Bi-slotted tree based anti-collision protocols for fast tag identification in RFID systems

This paper is intended to present bi-slotted tree based RFID tag anti-collision protocols, bi-slotted query tree algorithm (BSQTA) and bi-slotted collision tracking tree algorithm (BSCTTA). Diminishing prefix overhead and iteration overhead is a significant issue to minimize the anti-collision cost. For fast tag identification, BSQTA and BSCTTA use time divided responses depending on whether the collided bit is `0' or `1' at each tag ID. According to the simulation results, BSQTA and BSCTTA require less time consumption for tag identification than the other tree based RFID tag anti-collision protocols     

基于RFID技术的自适应分组标签防碰撞算法研究

RFID技术具有安全可靠、可远距离识别等特点,被广泛应用于智能识别与机器人技术中。传统的类标签算法普遍存在不足,文中基于RFID技术研究了自适应分组的标签防碰撞算法。自适应分组的标签防碰撞算法在一定程度上改善了多目标标签的情形,提高了系统的识别速度,且利用了阅读器与标签中的信息通道。仿真结果表明,自适应分组标签防碰撞算法可以大幅减少能量损耗,提高识别精度,弥补了传统算法的不足。     

Enhanced binary search with cut-through operation for anti-collision in RFID systems

RFID systems allow contactless identification of objects using radio frequency. When there is more than one transponder within the interrogation area of a reader, all the transponders may send data (or tags) at the same time which may lead to mutual interference. This event causes data loss and is referred to as a collision. In this letter, we propose an enhanced binary search with cut-through operation to minimize the anti-collision cost. The analytic results show that the proposed scheme achieves low delay in the collision resolution with low power consumption.     

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.     

基于分组策略的RFID自适应防碰撞算法的研究

针对射频识别系统中的标签碰撞问题,提出了一种基于分组策略的RFID自适应防碰撞算法。该算法在二叉树搜索算法的基础上引入分组策略、后退策略、自适应地选择四叉树搜索策略和动态调整标签碰撞检测过程策略,减少了搜索次数和读写器与标签间的通信量,提高了识别效率。     

Analysis and design of power efficient semi-passive RFID tag

The analysis and design of a semi-passive radio frequency identification(RFID) tag is presented.By studying the power transmission link of the backscatter RFID system and exploiting a power conversion efficiency model for a multi-stage AC-DC charge pump,the calculation method for semi-passive tag's read range is proposed.According to different read range limitation factors,an intuitive way to define the specifications of tag's power budget and backscatter modulation index is given.A test chip is implemen...     

高能效半有源射频识别标签的分析与设计

本文介绍了一款半有源射频识别标签的分析与设计。通过将多级AC-DC电荷泵的能量转换效率模型引入到反向散射射频识别系统的功率传输链路中,本文给出了计算半有源标签最大读写距离的数学方法,以及当读写距离限制因素改变时,制定标签功耗设计指标和反向散射调制系数的方法。在理论分析的指导下,本文设计了一颗半有源标签的测试芯片,芯片采用SMIC 0.18 μm标准CMOS工艺流片实现。主要的功能模块包括了一个采用阈值补偿技术的电荷泵和采用功率唤醒模式的低功耗唤醒电路。本文设计的半有源标签完全兼容EPC C1G2标准,芯片面积为0.54 mm2,支持输出电压在1.2到2.4 V范围内的电池。     

Framed slotted ALOHA with grouping tactic and binary selection for anti-collision in RFID systems

9%-16.3% compared to other ALOHA-based tag anti-collision algorithms when the number of tags is 1 000.     

Improved RFID anti-collision algorithm

In this paper, we propose an improved anti-collision technique based on the binary search algorithm. The improvement is achieved thanks to the manner of the requests’ building. This latter reduces considerably the responding tag's numbers and therefore, decreases the probability of bit's collision. Further, the algorithm provides a noticeable advantage for the length of transmitted binary data compared against basic binary search and dynamic binary search algorithms. Besides, it provides same performance in terms of average request's number making the identification process faster, and the expose time of information is then reduced.     

Adaptive frame on binary splitting for radio frequency identification anticollision

In many radio frequency identification applications, the reader must repeatedly identify the same staying tags. Existing anticollision protocols, adaptive binary splitting (ABS) and adaptive query tree, can rapidly identify the staying tags by remembering the order in which the tags were recognized in the previous identification process. This paper proposes a novel protocol called adaptive frame ABS (AFA), based on ABS. AFA utilizes the dynamic regulation approach that estimates the numbers of staying tags and newly‐arriving tags and optimally adjusts the numbers of slots allocated for them to reduce idle slots when many recognized tags leave and reduce collision slots when many newly‐arriving tags enter. Following the regulation process, multiple staying tags may share the same slot and cause a collision among them. Thus, an efficient ordering splitting is proposed to deterministically split the collided staying tags according to the order in which they were recognized. The analytical and simulation results show that AFA outperforms ABS in most of the considered environments. Copyright © 2012 John Wiley & Sons, Ltd.     

基于时隙预测的RFID防碰撞ALOHA算法

在得出EPC协议防碰撞机制中累加因子C的基础上,通过比较预设差值门限的方法调整帧长,并明确了识别结束条件;同时,采用时隙预测二进制选择机制对下一时隙响应标签数量进行预测,对空闲时隙加速跳过,碰撞时隙进行实时二进制散列处理,从而减少无效时隙的出现.仿真结果表明,改进后的算法能够有效增加系统吞吐率,降低开销与时延,为将RFID标签作为感知终端的物联网系统在数据采集方面提供了合理的解决方案.     

Secure and efficient lightweight RFID authentication protocol based on fast tag indexing

During the radio‐frequency identification authentication process, it is of great significance to quickly find out the target tag from all tags stored in the database, because it affects the authentication performance to a great extent. Most of the existing schemes use the Hash or pseudorandom number generator operation to locate the target tag, but if the number of tags is extremely large, vast Hash or pseudorandom number generator operations may take much time and lower the authentication efficiency. To locate the target tag quickly, the RAP and LADP protocols adopt the simple value comparison method, and the back‐end server can easily find the target tag by directly comparing the received index‐pseudonym value with those stored in the database. This method does improve the authentication performance, but it results that these schemes suffer from the tag tracking attack. Motivated by these concerns, we propose a novel tag indexing method called the two‐layer tag indexing mechanism, and at the same time, we give a lightweight radio‐frequency identification authentication protocol based on it. Analyses show that our scheme can effectively resist the tag tracking attack and is almost as efficient as the RAP and LADP protocols in indexing tags. Copyright © 2013 John Wiley & Sons, Ltd.     

RFID防碰撞算法的研究

随着物联网技术的高速发展,作为其关键技术之一的RFID显得愈为重要。标签碰撞的应用在RFID系统中是不可避免的,因此RFID防碰撞算法是RFID系统中一个重要问题,直接决定了RFID系统可以识别多个标签的能力。目前防碰撞算法在时域上主要可以分为非确定性算法（ALOHA算法）和确定性算法（树形算法）两大类。本文分析了现存的两大类算法中主流的防碰撞算法,总结出两大类算法的优点以及存在的问题。通过MATLAB仿真进一步证明此结论,并总结未来研究中需要继续关注的问题与方向。     

Differential RCS of RFID tag

The differential radar cross-section (RCS) of an RFID tag is an important parameter which determines the power of the modulated backscattered tag signal. The vector differential RCS of an RFID tag as seen by the reader is analysed and, for the first time, compared with experimental results in UHF band     

改进的树型结构RFID防碰撞算法

将整棵大查询树分为若干分支,在每一个分支内进行标签识别,减少碰撞发生的概率。算法分为前缀确定和分支查询2个阶段,在前缀确定阶段读取所有标签前缀,每个前缀代表一个分支,依次遍历每一分支;查询过程采用后退式搜索策略和动态搜索方式。理论分析和仿真实验表明,算法能够从查询次数、时延、吞吐率多方面改善RFID系统的整体性能。     

改进的基于ALOHA的RFID防碰撞算法

为了解决RFID系统中电子标签识别效率不高的问题,对基于ALOHA的随机性防碰撞算法进行了详细分析,提出了一种新的ALOHA防碰撞算法.在该算法中,针对标签估计,采用动态调整的方式自动改变标签估计式中的系数,使得标签估计个数随着已识别的标签数动态变化,从而估计下一帧待识别标签数;而对于帧长调整,根据估计的标签数,通过帧长与标签数分组的关系确定.通过MATLAB进行仿真,结果表明,该算法能明显提高系统的吞吐率和稳定性.     

RFID系统中标签天线的设计

本文根据微带天线的基本理论,设计出了一款用于标签的微带对称振子天线.该天线的中心频率为915MHz,回波损耗为-25.596dB;但是该天线阻抗带宽较窄,在VSWR<2的条件下,带宽为20.375%.