一种改进的RFID多标签防碰撞算法

在射频识别系统中,需要一种防碰撞算法使阅读器在可读范围内快速地识别出所有标签。提出了一种改进的ID预测算法以解决标签碰撞问题。该算法的最大特点是：阅读器向标签发出一次询问命令,有可能同时识别多个标签。此算法能有效地减少阅读器发送询问指令的次数,从而缩短识别出所有标签的时间。     

一种改进的信息位编码自适应搜索防碰撞算法

在信息位编码自适应搜索防碰撞算法的基础上,通过改进碰撞位信息查询方法,提出了一种改进型信息位编码自适应搜索防碰撞算法。通过信息位编码避免了空闲时隙,在多叉树搜索的同时对多个碰撞位进行编码查询,避免了碰撞位信息附加查询时隙。根据碰撞位的个数和最高碰撞位的位置信息,阅读器自适应地选择对标签进行信息位编码多叉树搜索或二叉树搜索。仿真结果表明,相对于信息位编码自适应搜索防碰撞算法,新算法的总时隙数减少了17.8%,吞吐率提高了21.5%。     

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.     

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.     

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.     

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.     

分组自适应分配时隙的RFID防碰撞算法研究

为了解决射频识别(Radio Frequency IDentification,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,提出一种基于分组自适应分配时隙的RFID防碰撞算法(GAAS).首先让阅读器对标签随机所选的时隙进行扫描统计,并将其发送给每一个标签,标签再进行相应地时隙调整,使阅读器跳过空闲时隙和碰撞时隙,自适应地分配有效时隙,进而对标签进行快速识别.当未识别标签数比较大时,算法采用分组以及动态调整帧长等策略,以减少时隙处理的时间.仿真结果表明:GAAS算法提高了系统的识别效率和稳定性,降低了传输开销.特别是当标签数超过1000时,该算法的吞吐率仍保持在71%以上,比传统的帧时隙ALOHA-256算法和分组动态帧时隙ALOHA算法的系统效率分别提高了300%和97.2%.     

基于信息位编码的自适应搜索RFID防碰撞算法研究

无线射频识别（RFID）技术可实现对目标物体的自动识别.为了减少对物体标签识别时间,提出一种基于信息位编码的自适应搜索的防碰撞（AS）算法.读写器充分利用碰撞位信息,要求标签返回碰撞位编码信息,进而自适应地生成有效查询前缀,对标签进行无空闲时隙识别,以减少查询次数,提高算法的性能.此外,AS算法也解决了读写器与标签通信中传输信息冗余等问题.本文通过理论分析证明了该算法的有效性,其中吞吐率的理论值与实验值的误差不超过5%,还从时间复杂度和通信复杂度对该算法进行了详细地分析.仿真结果表明：AS算法不仅提高了系统的性能,而且还降低了标签能量的消耗.特别是当标签数为1000时,该算法的吞吐率仍保持在61%左右,比查询树算法和自适应多叉树算法的系统效率分别提高了72%和20.1%左右.     

一种快速获取同频数据的防碰撞算法

文章在碰撞二叉树算法(CT)技术的基础上提出一种用于433 MHz频段下的标签防碰撞算法——改进型碰撞二叉树算法(ICT),可以很好地对各类土地的地形分布数量等特征进行测量。该算法根据首次碰撞码字进行前缀生成和标签组区分,在标签快速识别中,对每一个标签使用了一个计数器和一个指针,用来记录阅读器的历史序列,从而使得阅读器不需要传输整个前缀序列。仿真结果表明,ICT算法在当标签ID具有类似的前缀时,表现出优于CT算法的性能。     

多阅读器协作的RFID标签树形防碰撞算法

在物联网复杂的应用环境中,射频识别技术中的标签碰撞问题作为造成其系统标签识别时间长,通信量大等问题的主要原因,已成为近年来本领域的核心研究热点之一.针对以上问题,本文提出一种多阅读器协作的树形防碰撞算法：在第一阶段,根据位追踪技术能够识别标签碰撞位的特点,阅读器通过判别待识别标签中的碰撞位,从待广播节点中删除已验证的无效节点;在第二阶段的循环广播中,阅读器间通过共享每次的广播的前缀与当次广播结果对自身的树形结构进行不断优化,优化策略是为每一个阅读器分配一个待广播节点队列,通过共享的信息计算待广播节点中含有标签的概率,依据其概率调整队列中待广播节点的优先级,并不断地删除无需广播的节点.在下一轮广播中阅读器选取含有标签概率最大的节点进行广播.仿真实验结果表明：提出的算法的平均标签识别效率达到59.9%,并且在总时隙数量方面有一定优势.     

A Collision Arbitration Protocol Based on Specific Selection Function

Fast and eff ective identifications of a large number of items are required in many Radio-frequency identification (RFID) applications. Simultaneous responses from multiple tags are corrupted by collisions and thus re-sult in low identification efficiency. To address the prob-lem of low identification eifficiency, many existing tag anti-collision algorithms try to schedule the identification pro-cess to avoid collisions. A novel anti-collision scheme based on specific selection function is presented, in which tags pick a slot according to a selection function instead of be-ing randomly assigned to slots within a frame. If collision occurs, the reader sends the custom command SETBM ac-cording to the collision information. When probed by the SETBM, the tags apply the selection function to its partial ID and send the mapped result to the reader. According to the mapped result, the reader assigns the time slot to the tags. All tags collided in the same slot will be identified by the tree traversal scheme. Compared to the most of exist-ing anti-collision algorithms, simulation results show that our proposed algorithm can achieve better performance in terms of identification efficiency, time efficiency, and en-ergy consumption.     

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。     

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.     

Low Access Delay Anti-Collision Algorithm for Readers in Passive RFID Systems

Even though radio frequency identification (RFID) systems are spreading more and more as a medium for identification, location and tracking purposes, some reliability issues of these systems still need to be solved. In fact, RFID readers and tags experience collisions when sharing the wireless transmission channel over the same area. In this work, we propose a centralized scheduling-based algorithm as possible candidate solution for the reader collision problem in passive RFID systems. This algorithm has been designed taking into account the circuitry limitations of the tags, which do not allow the usage of frequency or code division multiple access schemes in passive RFID systems. The solution herewith proposed, which is suitable for those scenarios involving static or low mobility readers, aims at preventing reader collisions and provides at the same time low channel access delay to the readers. The performance of this algorithm has been tested via computer simulations. The results show that the proposed solution strongly reduces collision occurrences and, especially in static scenarios, provides low access delay to the readers during the channel contention phase.     

基于标签识别码分组的连续识别防碰撞算法研究

标签碰撞增加了射频识别(RFID)系统的时间开销和无源标签的能量消耗,降低了识别速率。该文提出了一种适用于标签识别码连续的防碰撞算法UIG算法,该算法首先根据公司编码和产品编码将所有标签分组,再由产品序列号的碰撞信息生成每组的两个初始标签识别码。最后,通过对初始标签识别码分别连续减1和加1识别出所有标签。性能分析和仿真结果显示,该算法在时间复杂度和通信复杂度上都有很大改善,吞吐率得到了大大的提高。     

Two Blocking Algorithms on Adaptive Binary Splitting: Single and Pair Resolutions for RFID Tag Identification

In radio frequency identification (RFID) systems, the reader identifies tags through communication over a shared wireless channel. When multiple tags transmit their IDs simultaneously, their signals collide, increasing the identification delay. Therefore, many previous anti-collision algorithms, including an adaptive query splitting algorithm (AQS) and an adaptive binary splitting algorithm (ABS), focused on solving this problem. This paper proposes two blocking algorithms, a single resolution blocking ABS algorithm (SRB) and a pair resolution blocking ABS algorithm (PRB), based on ABS. SRB not only inherits the essence of ABS which uses the information of recognized tags obtained from the last process of tag identification, but also adopts a blocking technique which prevents recognized tags from being collided by unrecognized tags. PRB further adopts a pair resolution technique which couples recognized tags and thus only needs half time for next identifying these recognized tags. We formally analyze the performance of SRB and PRB. Finally, the analytic and simulation results show that SRB slightly outperforms ABS and PRB significantly surpasses ABS.     

Network Information Security Data Protection Based on Data Encryption Technology

Today Radio Frequency Identification systems (RFID) are one of the most usable automated wireless identification technologies in the internet of things. Identification systems can exchange data remotely by communicating between a tag and a reader with sending radio waves. The main challenge of identification systems with radiofrequency in a dense RFID network is the collision, which occurs when readers are located in each other's interference range and start reading tags simultaneously. With these collisions happening, readers cannot read all the tags around them in the efficient time durations. In this research, using a distributed method and the channel listening technique, readers select a time interval to take the control channel by the Geometric Probability Distribution Function. Also, by measuring the signal strength from neighboring readers and sharing tag information, there will be an increase in the throughput of identification systems through radio waves while avoiding all kinds of collisions in the control channel. Extensive results show that the proposed method has better throughput and has less average waiting time.