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。     

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。     

分组N叉跟踪树型RFID防碰撞算法研究

针对无线射频识别(RFID,Radio Frequency Identification)标签多路访问产生的信号碰撞问题,提出了基于碰撞位跟踪的分组N叉跟踪树型RFID防碰撞算法(CBGN,Collision Bit Tracking Tree Algorthm Based on Grouping N-ray).利用极大似然位估算法(MLE,Maximum Likelihood Bit Estimation)估算应用环境下标签的数量.在MLE基础上根据标签标识(ID)将标签分配在不同分组内,并利用N叉树识别分组后的标签,CBGN算法通过分组及N叉识别两种策略相结合来降低碰撞概率及识别延时.最后,以通信复杂度为基准对不同N叉树下的最优分组系数进行了推导,从而获得最优N值及对应分组系数.理论分析和仿真实验表明,CBGN算法具有鲁棒性好和通信复杂度低的特点.     

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。     

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。     

分组自适应多叉树RFID防碰撞算法研究

提出了一种基于分组自适应多叉树的RFID防碰撞算法,该算法将标签分为多组并按分组处理标签,减少同一时刻同时响应的标签的数目,从而减少碰撞发生的概率,对同一分组的标签,按照碰撞因子自动选择动态二叉树或动态四叉树搜索,同时采用后退策略。仿真结果表明,该算法在平均查询次数及传输数据量上较其他算法都有较大提高.     

基于CDMA和动态时隙ALOHA的UHF RFID防碰撞研究

为提高UHF RFID系统防碰撞性能,提出了一种基于码分多址(CDMA)和动态时隙ALOHA相结合的超高频RFID无源标签防碰撞识别方案。设计了标签防碰撞性能评估方案,采用Matlab进行仿真分析。性能分析和仿真结果显示,该方案在尽可能降低标签硬件复杂度和功耗的前提下,充分利用了码分多址和动态时隙ALOHA的性能,允许多个标签同时发送数据,提高了标签的识别速率。     

基于二进制树分解的动态防碰撞算法

针对现有的无线射频识别系统（RFID）二进制树防碰撞算法所需的搜索时隙较多,系统识别速率较低,提出了一种基于二进制树分解的动态防碰撞算法。该算法利用标签EPC的唯一性,对发生碰撞的比特位进行深度分解,根据碰撞位调整搜索状态,从而进一步减少搜索时隙数并提高了系统的呑吐量。通过对算法的分析和仿真结果表明：基于二进制树分解的动态防碰撞算法相对于动态二进制搜索算法有明显的优势。     

Minimising collisions in RFID data streams using probabilistic Cluster-Based Technique

Radio Frequency Identification (RFID) uses wireless radio frequency technology to automatically identify tagged objects. Despite the extensive development of the RFID technology in many areas, tags collisions still remain a major problem. This issue is known as the collision problem and can be solved by using anti-collision techniques. Current probabilistic anti-collision approaches suffer from tag starvation due to the inaccurate Backlog estimation and have a low performance in some cases. In this research, we propose a Probabilistic Cluster-Based Technique (PCT) to maximise the performance efficiency during the tag identification process. The PCT approach creates new tag grouping strategies using particular equations, according to the optimal efficiency obtained for a specific number of tags. Through extensive experimentation, we have demonstrated that the proposed concept performs better than the other current state-of-the-art approaches.     

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.     

Split-aloha algorithm for radio frequency identification system

Anti-Collision algorithm is one of the most important components of radio frequency identification (RFID) technology, which possesses a key position in the performance of the whole system. ALOHA algorithm is one of the most popular methods to solve the collision problem because of its efficiency and practicability. The grouping method has been developed for enhancing the performance of conventional ALOHA when there are thousands of tags. However, the existing grouping method has limitations in applications due to its rigorous requirements for the estimation of the number of backlog tags or the admirable characteristics of the tags' ID number. Working on the improvement of the grouping methods, we proposed an algorithm named split-ALOHA with a novel grouping method that split tags as a binary tree. The novel grouping method makes it more practicable than the existing grouping methods due to the simplified requirements for tags. Simulations of the proposed algorithm show the superior performance of a linearly increasing of the number of consumed time slots while the number of tags increases. The algorithm performance analysis between split-ALOHA and ALOHA algorithms with other grouping methods has been implemented in a proper way.     

Application of ICA-based anti-collision algorithm in RFID system

Data collision problem exists in radio frequency identification (RFID) system when tabs are present in the interrogation zone of a single reader at the same time. Though different anti-collision methods have been proposed, it still needs further study on how to improve the identification ability especially in the interference circumstance. This paper presents a new method based on independent component analysis (ICA) algorithm. Coded division multiple access (CDMA) technology is adopted at the transmitter and the maximum signal to noise ratio is applied at the receiver of the RFID system. The proposed method has been verified by computer simulation which shows that the system can separate different users’ source data correctly based on ICA algorithm and has better performance compared with the traditional CDMA technology.     

IDMA Based Anti-collision in RFID Networks

Even though object identification is its main objective, it is generally accepted that there are some technological challenges that should be addressed in order to exploit the full potential of RFID (Radio frequency identification). The anti-collision problem is one of them. Despite the different proposed methods, it still needs further study on how to improve identification ability. This paper presents a novel algorithm with IDMA (Interleave division multiple access) scheme to resolve the anti-collision problem for RFID. IDMA, which is one of the most promising technologies for high data rate wireless systems, can be regarded as a special case of CDMA (Code division multiple access). In contrast to CDMA, which separates tags by signatures or spreading codes, distinct interleavers are the only means to separate tags for IDMA. In this paper, a RFID based IDMA receiver is proposed and compared to classical systems. Simulation results demonstrate that this system provides an improvement in performance in terms of bit error rate in dense scenarios (large number of tags) and it offers an efficient alternative to systems with classical spreading sequence.     

基于混沌序列的超高频RFID防碰撞及安全协议设计(英文)

Collision and security issues are considered as barriers to RFID applications.In this paper,a parallelizable anti-collision based on chaotic sequence combined dynamic frame slotted aloha to build a high-efficiency RFID system is proposed.In the tags parallelizable identification,we design a Discrete Markov process to analyze the success identification rate.Then a mutual authentication security protocol merging chaotic anti-collision is presented.The theoretical analysis and simulation results show that the proposed identification scheme has less than 45.1%of the identification time slots compared with the OVSF-system when the length of the chaos sequence is 31.The success identification rate of the proposed chaotic anti-collision can achieve 63%when the number of the tag is100.We test the energy consumption of the presented authentication protocol,which can simultaneously solve the anti-collision and security of the UHF RFID system.     

A New Scalable Lightweight Grouping Proof Protocol for RFID systems

Radio-frequency Identification (RFID) grouping proof protocol is widely used in medical healthcare industry, transportation industry, crime forensics and so on,it is a research focus in the field of information security. The RFID grouping proof protocol is to prove that some tags belong to the same group and exist simultaneously. To improve the applicability of the RFID grouping proof protocol in low cost tag applications, this paper proposes a new scalable lightweight RFID grouping proof protocol. Tags in the proposed protocol only generate pseudorandom numbers and execute exclusive-or(XOR) operations. An anti-collision algorithm based on adaptive 4-ary pruning query tree (A4PQT) is used to identify the response message of tags. Updates to secret information in tags are kept synchronized with the verifier during the entire grouping proof process. Based on these innovations, the proposed protocol resolves the scalability issue for low-cost tag systems and improves the efficiency and security of the authentication that is generated by the grouping proof. Compared with other state-of-the art protocols, it is shows that the proposed protocol requires lower tag-side computational complexity, thereby achieving an effective balance between protocol security and efficiency.     

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.