基于比特查询的多进制树标签防碰撞识别协议

多标签碰撞问题被认为是射频识别系统中的一个关键问题.近来,许多基于比特追踪技术的查询树算法被提出用于有效的解决标签碰撞问题,然而由于无用的碰撞比特信息和空闲时隙的存在,这些查询树算法的性能都有待进一步提升.本文提出了一种基于比特查询的查询方法,该算法使得标签返回一个映射过比特串来取代原始的ID序列.同传统的ID查询相比较,比特查询不仅可以消除空闲查询还可以将碰撞标签分成更多子集并充分利用碰撞比特信息.基于该比特查询方法,我们提出了一种基于比特查询的多进制树（Bit query based M-ary tree,BQBMT）新型查询树算法,它通过多进制树迭代的分离碰撞,并通过比特查询模式和ID查询模式之间的最佳切换来快速识别标签.理论分析和仿真结果显示,BQBMT算法的的系统效率接近0.89,超过了现有的QT算法和混合防碰撞算法.     

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。     

应用标签并行识别技术的RFID防碰撞算法

针对RFID传统算法一次只能识别一个标签、吞吐率低、饿死率高的不足,文中提出一种RFID系统防碰撞算法,即利用伪ID码分组,并应用标签可并行识别技术的防碰撞算法（PILD算法）。PILD算法利用伪ID码对待识别标签进行分组,当出现碰撞现象时,运用并行识别算法对出现碰撞的标签进行识别。该算法能避免因帧长过大造成吞吐率下降的问题,并提高RFID识别技术的吞吐率。首先对PILD算法的识别过程进行理论分析,再运用Mathematica软件对PILD算法进行仿真。理论分析及仿真结果表明：当标签总数为2 000,单次碰撞标签数小于等于6时,标签平均查询次数近似为1.26次;该算法的吞吐率较稳定且达到0.791 092,与基于伪ID码的树型防碰撞算法和Logistic-DFSA算法相比,所提算法吞吐率分别提高28.82%、4.74%;当标签数大于1 400时,PILD算法的标签总查询次数最少,标签平均查询次数最少。所提算法中伪ID码分组能够减少单个标签因多次碰撞发生“饿死现象”的概率,与基于伪ID码的树型防碰撞算法和Logistic-DFSA算法相比,PILD算法饿死率最低。     

基于分组机制的位仲裁查询树防碰撞算法

提出了一种基于分组机制的位仲裁查询树(GBAQT, bit arbitration query tree based on grouping mechanism)算法。该算法根据标签ID自身特征分组,采用3位仲裁位来取代传统1位仲裁识别标签的方式,通过碰撞位信息得到传输数据,从而能避免一些空闲时隙。算法的性能分析和仿真结果表明,GBAQT防碰撞算法具有较少的总时隙数,系统效率和时隙利用率也明显优于其他算法。     

基于查询树的防碰撞算法性能分析与研究

多标签碰撞问题严重影响射频识别系统的性能.基于查询树的防碰撞算法作为一种确定性算法被广泛的应用于各类射频识别场景中.本文分析了主流查询树防碰撞算法的性能与不足,并基于查询树方法提出了一种时间有效的防碰撞算法.该算法基于传统查询树识别模型,实施了一种双查询前缀匹配方法,可以消除传统查询树方法中的空闲时隙.此外,提出的算法可以充分利用碰撞时隙来提高识别效率.理论分析和仿真结果表明该算法优于现有的查询树防碰撞算法.     

自调整混合树RFID多标签防碰撞算法

在RFID系统中,阅读器读取标签的效率与解决标签发生碰撞的方法密切相关.目前采用多叉树查询是一种较好的多标签防碰撞方法.它能减少碰撞时隙,再通过额外的查询来减少空闲时隙.但额外的查询也增加了新的开销.本文提出了一个自调整混合树RFID多标签防碰撞算法,该算法根据最高两个碰撞位的特征,在不增加额外查询的条件下,自调整搜索树的叉数,从而避免了一些碰撞时隙和空闲时隙.通过对算法的性能分析和仿真结果可以看到,自调整混合树RFID多标签防碰撞算法具有较少的时间复杂度和通信复杂度,识别效率也明显高于其他多叉树算法.     

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.     

并行识别 RFID 自适应多叉树防碰撞算法

针对自适应多叉树防碰撞算法的吞吐量不稳定性和“误判”问题,提出一种并行识别的R F ID标签防碰撞算法。该算法利用OVSF扩频码技术,在时隙内开拓码道,当碰撞发生时能够并行识别标签ID信息,减缓由标签数量增大而造成的碰撞累积。理论分析表明算法的吞吐量随OVSF扩频码码长增大而提高。仿真分析表明该算法有效地提高了R F ID系统的防碰撞性能。     

基于码分多址防碰撞的射频识别认证协议

该文针对射频识别(RFID)领域中的安全认证协议和多标签防碰撞算法两个研究热点,设计了一种基于码分多址防碰撞算法的RFID安全认证协议。协议支持密钥的动态更新并引入标志位机制选择备用密钥来抵御数据库同步攻击,同时结合码分多址技术,应用重传随机数进行扩频码的选择,实现一次重传解决多标签识别中因数据碰撞造成的标签不识别的问题。首先,描述协议的流程及防碰撞原理;其次,应用SVO逻辑对认证协议的正确性进行证明;最后,对应用该认证协议的系统吞吐效率进行数值分析,分析表明其吞吐效率高于传统防碰撞算法。     

改进型自适应多叉树防碰撞算法研究

 文章在自适应多叉树防碰撞算法的基础上,通过优化阅读器所发送前缀的方法,提出了一种改进型自适应多叉树(IAMS)防碰撞算法.该算法通过计算碰撞因子来动态地选择搜索树的叉数,并对四叉树的查询前缀进行优化,从而避免了大量的空闲时隙.文章通过数学分析,准确地描述了IAMS算法识别标签所需的时隙数.仿真结果表明,改进型自适应多叉树防碰撞算法具有更快的识别速度和更高的系统吞吐率.     

Multi-branch query tree protocol for solving RFID tag collision problem

The technology of anti-collision is a key point in radio frequency identification （RFID） system. To avoid data collision, there are two approaches： ALOHA based algorithm and binary tree （BT） based algorithm. However, these cannot solve the collision problem completely, especially when the tag quantity is big and the tag ID is long. In this article, we present a multi-branch query tree （MBQT） protocol based on balanced incomplete block design （BIBD） code, and use 16-bit vectors derived from the BIBD as query prefix symbols of RFID reader. Compared with the conventional anti-collision algorithm, the theoretic analysis and simulation show that the proposed protocol improves the identification efficiency.     

一种自适应的无线射频识别系统中的防冲突算法(英文)

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.     

Evaluating the energy consumption of the RFID tag collision resolution protocols

RFID technology acts as a bridge to connect the physical world with the digital space, and RFID system is pervading our daily life in the last few years. The energy consumed by the reader and a tag in resolving the collisions caused by multiple tags is a key issue that affects life time of mobile reader and active tags, as well as the identification accuracy of passive tags. In this paper, the energy consumed by the reader and a tag in resolving the tag collision is examined for the commonly used RFID tag collision resolution protocols, including the frame slotted ALOHA based and the binary query tree based protocols. Numeric evaluation is also performed and the result verifies that regarding to energy consumption, the dynamic frame slotted ALOHA protocol for the Class-1 RFID system performs best among the frame slotted ALOHA protocols, and the modified binary query tree protocol also performs better than the standard binary query tree protocols.     

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     

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。     

A new anti‐collision algorithm for RFID tag

We present a new radio frequency identification tag anti‐collision algorithm in this paper. The main idea of this algorithm is that we should find the collided bit at first, and every tag contains a register RC, which has length the same as the tag's ID length to store the conflict bit, then all the subsequent processing are based on the conflict bit. In this new algorithm, tag uses a binary pulse string to transfer data to the reader, compared with the traditional query tree‐based algorithms, which is based on the tag's ID; this new algorithm is more efficient and requires fewer read cycles for tag's identification. Copyright © 2013 John Wiley & Sons, Ltd.     

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.