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.     

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。     

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.     

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).     

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。     

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.     

ASAF ALOHA Protocol for Dense RFID Systems

RFID tags are used for varied applications in large numbers. Human Tracking is one such important application wherein the RFID system detects the presence of a tag in a dense tag environment. Quick estimation of the number of tags in the field at a desired level of accuracy is one of the most common requirements in the present scenario. Identification of tags has become a critical area which need more time and unsuitable in many situations; especially where tag set is dense. We introduce a novel medium access control (MAC) protocol for Radio Frequency IDentification (RFID) systems which exploits the statistical information collected at the reader. The protocol, termed Adaptive Slot Adaptive Frame (ASAF) ALOHA protocol, is motivated to significantly improve the total read time performance of the currently suggested MAC protocols for RFID systems by minimizing the collisions of the tags. In order to perform this task, ASAF estimates the dynamic tag population and adapts the frame size and number of slots simultaneously in the subsequent round via a simple policy that maximizes an appropriately defined function. We demonstrated that ASAF is better than the current RFID MAC protocols. We also considered the case where suddenly if the number of tags increases, the running frame with adapted slots gets flushed away and new frame with increased number of slots gets adapted automatically by the system showing the robustness in this case as well.     

Energy-Aware Tag Anticollision Protocols for RFID Systems

Energy consumption of portable RFID readers is becoming an important issue as applications of RFID systems pervade many aspects of our lives. Surprisingly, however, these systems are not energy-aware with the focus till date being on reducing the time to read all tags by the reader. In this work, we consider the problem of tag arbitration in RFID systems with the aim of designing energy-aware anticollision protocols. We explore the effectiveness of using multiple time slots per node of a binary search tree through three anticollision protocols. We further develop an analytical framework to predict the performance of our protocols and enable protocol parameter selection. We demonstrate that all three protocols provide significant energy savings both at the reader and tags (if they are active tags) compared to the existing Query Tree protocol, while sharing the deterministic property of the latter. Further, we show that our protocols provide similar benefits even with correlated tag IDs.     

改进型动态时隙冲突跟踪树标签防碰撞算法

射频识别RFID(Radio Frequency Identification)系统内的读卡器在识别大数量标签时常因信号的碰撞而导致系统识别效率降低.动态时隙冲突跟踪树算法DSCTTA(Dynamic Slots Collision Tracking Tree Algorithm)采用动态时隙应答机制可减少前缀开销和迭代开销,但会产生大量空闲时隙.本文将DSCTTA和比特转换方式(BCM)相结合,得到改进型动态时隙冲突跟踪树标签防碰撞算法(IDSCTTA)以防止标签冲突,加快标签识别速度.理论分析及仿真结果表明,IDSCTTA不仅具有DSCTTA的全部优点,而且能够有效地减小识别时延和提高时隙效率,并且标签数目越大,算法性能越优越.     

A Novel RFID Tag Identification Protocol: Adaptive n-Resolution and k-Collision Arbitration

Since radio frequency identification (RFID) technology has become increasingly common in numerous applications, including large-scale supply chain management, improving the efficiency of RFID tag identification is an important task. In practical settings, the identification of RFID tags often occurs in a dynamic environment, in which tags move through a specific interrogation range. However, the literature contains few studies on the design of efficient identification protocols in dynamic environments. This study proposes a novel tag identification protocol that is particularly efficient in dynamic environments. the proposed protocol involves two anti-collision techniques: adaptive n-Resolution (AnR) and k-Collision Arbitration (kCA). These two techniques significantly improve the tag identification delay and communication overhead. This improvement is primarily due to the use of a newly designed challenge-response bit sequence mechanism and the information obtained from the previous tag identification procedure. As a result, AnR requires only a constant number of interrogation times regardless of the number of target tags, while kCA further improves the efficiency of tag identification with \(k\) -splitting collision arbitration. Rigorous analysis and simulation experiments show that this tag identification protocol significantly outperforms related methods (by at least 48.85 % identification delay and 23.87 % communication overhead can).     

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.     

无后台服务器的射频识别标签安全查询协议

在许多射频识别(RFID)应用中,经常需要在多个标签中确定某个特定标签是否存在。在这种环境下,标签查询协议必不可少。然而,已有的协议要么存在安全漏洞,要么查询效率低下。利用Hash函数和时间戳,提出一个无后台服务器的RFID标签查询协议。GNY逻辑被用于证明新协议的正确性。分析显示提出的协议可以高效的实现特定标签的查询,且能够抵抗一些主要攻击,实现对标签隐私的保护。     

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.     

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.     

Analysis of energy consumption for multiple object identification system with active RFID tags

Radio frequency identification (RFID) systems are very effective for identifying objects. Existing published works focus on designing efficient collision resolution protocols for the tag identification problem in RFID systems with passive RFID tags. However, advances in low‐cost and low‐power sensing technologies will make active RFID tags more popular and affordable in the near future. In multiple object identification systems with active tags, the tags are designed for extremely low‐cost large‐scale applications such that battery replacement is not feasible. This imposes a critical energy‐constraint on the communication protocols used in these systems. In this paper, we analyze energy consumption and identification times for several protocols. The objective is to decrease energy consumption of tags by reducing both the total identification time and the total active time. Copyright © 2007 John Wiley & Sons, Ltd.     

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。     

物理层超高频射频识别标签信号分离中的信道估计

在被动式的超高频(UHF)射频识别(RFID)系统中,当多个标签选择同一个时隙向阅读器发送信息,标签间冲突就会产生,该冲突通常只在介质访问控制(MAC)层上解决。其实,若冲突信号在物理层上被分离,识别效率将能得到很大的提高。在物理层冲突信号分离中,信道估计是一项关键技术,因为好的信道估计有助于准确地恢复冲突信号。传统的信道估计方法在两个标签冲突的情况下具有较好的估计性能,但当冲突标签数超过2时,却会产生较高的误差。该文针对物理层的UHF RFID信号分离问题,提出一种新的信道估计方法。该方法利用已知的前缀信号,采用最小二乘方法对信道进行估计。从实验结果看,当标签冲突数超过2时,该文提出的信道估计方法的误差要小于传统的估计方法,而且估计的信道得到的分离效率也高于传统方法。     

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。