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.     

Gen2‐Based Tag Anti‐collision Algorithms Using Chebyshev's Inequality and Adjustable Frame Size

Arbitration of tag collision is a significant issue for fast tag identification in RFID systems. A good tag anti‐collision algorithm can reduce collisions and increase the efficiency of tag identification. EPCglobal Generation‐2 (Gen2) for passive RFID systems uses probabilistic slotted ALOHA with a Q algorithm, which is a kind of dynamic framed slotted ALOHA (DFSA), as the tag anti‐collision algorithm. In this paper, we analyze the performance of the Q algorithm used in Gen2, and analyze the methods for estimating the number of slots and tags for DFSA. To increase the efficiency of tag identification, we propose new tag anti‐collision algorithms, namely, Chebyshev's inequality, fixed adjustable framed Q, adaptive adjustable framed Q, and hybrid Q. The simulation results show that all the proposed algorithms outperform the conventional Q algorithm used in Gen2. Of all the proposed algorithms, AAFQ provides the best performance in terms of identification time and collision ratio and maximizes throughput and system efficiency. However, there is a tradeoff of complexity and performance between the CHI and AAFQ algorithms.     

A fast tag identification anti‐collision algorithm for RFID systems

In this work, we propose a highly efficient binary tree‐based anti‐collision algorithm for radio frequency identification (RFID) tag identification. The proposed binary splitting modified dynamic tree (BS‐MDT) algorithm employs a binary splitting tree to achieve accurate tag estimation and a modified dynamic tree algorithm for rapid tag identification. We mathematically evaluate the performance of the BS‐MDT algorithm in terms of the system efficiency and the time system efficiency based on the ISO/IEC 18000‐6 Type B standard. The derived mathematical model is validated using computer simulations. Numerical results show that the proposed BS‐MDT algorithm can provide the system efficiency of 46% and time system efficiency of 74%, outperforming all other well‐performed algorithms.     

An energy‐efficient,scalable and collision‐free MAC layer protocol for wireless sensor networks

Wide range of applications such as disaster management, military and security have fueled the interest in sensor networks during the past few years. Sensors are typically capable of wireless communication and are significantly constrained in the amount of available resources such as energy, storage and computation. Such constraints make the design and operation of sensor networks considerably different from contemporary wireless networks, and necessitate the development of resource conscious protocols and management techniques. In this paper, we present an energy‐efficient, scalable and collision‐free MAC layer protocol for sensor networks. The approach promotes time‐based arbitration of medium access to limit signal interference among the transmission of sensors. Transmission and reception time slots are prescheduled to allow sensors to turn their radio circuitry off when not engaged. In addition, energy consumption due to active to sleep mode transitions is minimized through the assignment of contiguous transmission/reception slots to each sensor. Scalability of the approach is supported through grouping of sensors into clusters. We describe an optimization algorithm for energy conscious scheduling of time slots that prevents intra‐cluster collisions and eliminates packet drop due to buffer size limitations. In addition, we also propose an arbitration scheme that prevents collisions among the transmission of sensors in different clusters. The impact of our approach on the network performance is qualified through simulation.. Copyright © 2004 John Wiley & Sons, Ltd.     

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。     

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.     

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).     

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.     

Tree-based backoff protocol for fast RFID tag identification

This paper proposes a tree-based backoff (TBB) protocol that reduces the number of iterations implemented in the procedure of tag collision arbitration in radio frequency identification (RFID) systems. This is achieved by employing the following mechanisms: one is send the request command iteratively to all tags in the interrogation zone until a single tag is identified. The other is backward to the parent node instead of root node to obtain the request parameters and send the request command again until all tags are identified. Compared with the traditional tree-based protocol, on average, simulated results show that the TBB protocol reduces the number of the iterations by 72.3% and the identification delay by 58.6% and achieves the goal of fast tag identification.     

Adaptive binary splitting for efficient RFID tag anti-collision

Tag collision arbitration for passive RFID tags is a significant issue for fast tag identification. This letter presents a novel tag anti-collision scheme called adaptive binary splitting (ABS). For reducing collisions, ABS assigns distinct timeslots to tags by using information obtained from the last identification process. Our performance evaluation shows that ABS outperforms other tree based tag anti-collision protocols.     

A Scheme to Increase Throughput in Framed‐ALOHA‐Based RFID Systems with Capture

In this paper, a scheme to increase the throughput of RFID systems is presented, which considers the capture effect in the context of framed ALOHA protocol. Under the capture model in which the probability of one tag is identified successfully depending on the number of tags involved in the collision, two probabilistic methods for estimating the unknown number of tags are proposed. The first method is the maximum likelihood estimation method, and the second method is an approximate algorithm for reducing the computational time. The optimal frame size condition to maximize the system throughput by considering the capture effect is also presented.     

Array‐based reader anti‐collision scheme for highly efficient RFID network applications

Radio frequency identification (RFID) is a technology for identifying objects by radio signal. The reader collision problem is caused by the interrogation zones overlap of multiple readers, and leading to incorrect and unreliable data. This study proposes an array‐based reader anti‐collision scheme (ARCS) for solving the reader‐to‐tag interference problem. This mechanism uses array and grouping techniques to schedule the active readers to reduce the read cycle (RC) time. The ‘RC’ and ‘collision ratio (CR)’ measures serve as performance indexes in the proposed scheme. From ‘RC’ comparison, the ARCS mechanism has the maximum improvement of 55 per cent as compared with the existing mechanisms. Furthermore, take ‘CR’ index, ARCS has the maximum improvement of 42 per cent as compared to the others. Copyright © 2008 John Wiley & Sons, Ltd.     

A smart exponential‐threshold‐linear backoff mechanism for IEEE 802.11 WLANs

Based on the standardized IEEE 802.11 Distributed Coordination Function (DCF) protocol, this paper proposes a new backoff mechanism, called Smart Exponential‐Threshold‐Linear (SETL) Backoff Mechanism, to enhance the system performance of contention‐based wireless networks. In the IEEE 802.11 DCF scheme, the smaller contention window (CW) will increase the collision probability, but the larger CW will delay the transmission. Hence, in the proposed SETL scheme, a threshold is set to determine the behavior of CW after each transmission. When the CW is smaller than the threshold, the CW of a competing station is exponentially adjusted to lower collision probability. Conversely, if the CW is larger than the threshold, the CW size is tuned linearly to prevent large transmission delay. Through extensive simulations, the results show that the proposed SETL scheme provides a better system throughput and lower collision rate in both light and heavy network loads than the related backoff algorithm schemes, including Binary Exponential Backoff (BEB), Exponential Increase Exponential Decrease (EIED) and Linear Increase Linear Decrease (LILD). Copyright © 2011 John Wiley & Sons, Ltd.     

CDMA-based anti-collision algorithm for EPC global C1 Gen2 systems

Frame slotted ALOHA protocol as a key technology to improve system throughput has been widely applied to modern radio frequency identification systems. In this paper, a novel frame slotted ALOHA collision arbitration protocol based on code division multiple access has been proposed. The main aim of the proposed algorithm is to avoid collisions between multiple tags. In the scheme, an orthogonal sequence is used as the means to distinguish the transmitted data from different tags within the same time slot and frequency band. The theoretical analysis and simulation results proved that the performance of our proposed algorithm outperforms the existing ALOHA-based protocols.     

多枝查询树协议在解决射频识别碰撞问题中的应用

数据碰撞是影响射频识别(RFID)系统识别效率的主要因素。目前,常用的防碰撞算法是ALOHA算法和二进制树搜索算法,但这两类算法都还不能完全解决标签碰撞问题,尤其是当待识别的标签数量较大且标签ID序列号较长时,识别速度相当慢。为此提出一种多枝查询树协议,采用均衡不完全区组设计(BIBD)对标签ID进行编码,并用16位的BIBD码作为读写器查询前缀符号。理论分析和仿真结果表明,这种协议的性能较传统的防碰撞协议有明显改善。     

Analysis of Priority R‐ALOHA (PR‐ALOHA) protocol

With the exception of required time synchronization, the Reservation‐ALOHA (R‐ALOHA) protocol is simple to implement and suitable for medium access control in ad hoc wireless networks. In this paper, we propose an innovative protocol, referred to as Reservation ALOHA with priority (PR‐ALOHA) that provides differentiated services on the basis of traffic priority. To date, the carrier sense multiple access/collision avoidance (CSMA/CA) protocol has been widely used for this purpose by employing an interframe spacing (IFS) for priority service, that is, nodes ready for packet transmissions are required to wait for an IFS amount of time, where a shorter IFS is used to gain faster access to the radio channel. However, sensing and collision avoidance mechanisms make CSMA/CA unsuitable for delay‐sensitive applications, that is, congested scenarios with high traffic. In contrast, the proposed PR‐ALOHA protocol may be considered a good candidate for such applications. In this paper, the performance of the PR‐ALOHA protocol is investigated analytically and by simulation. Its comparison with regular R‐ALOHA is also carried out. Modeling and simulation results of PR‐ALOHA show that PR‐ALOHA improves the performance of high‐priority traffic with limited effect on normal network traffic. Thus, PR‐ALOHA may be useful in vehicular communications, where traffic may be separated into emergency messages having high priority and multimedia messages having low priority. Copyright © 2013 John Wiley & Sons, Ltd.     

A Fully Integrated CMOS Security‐Enhanced Passive RFID Tag

A fully integrated CMOS security‐enhanced passive (SEP) tag that compensates the security weakness of ISO/IEC 18000‐6C is presented in this paper. For this purpose, we propose a security‐enhanced protocol that provides mutual authentication between tag and reader. We show that the proposed protocol meets the security demands of the ongoing international standard for RFID secure systems, ISO/IEC 29167‐6. This paper fabricates the SEP tag with a 0.18‐µm CMOS technology and suggests the optimal operating frequency of the CMOS SEP tag to comply with ISO/IEC 18000‐6C. Furthermore, we measure the SEP tag under a wireless environment. The measured results show that communications between the SEP tag and reader are successfully executed in both conventional passive and SEP modes, which follow ISO/IEC 18000‐6C and the proposed security enhanced protocol, respectively. In particular, this paper shows that the SEP tag satisfies the timing link requirement specified in ISO/IEC 18000‐6C.     

ABC algorithm‐based trustworthy energy‐efficient MIMO routing protocol

This paper introduces artificial bee algorithm (ABC)‐based energy‐efficient protocol with security for the enhancement of lifetime of wireless sensor network. A trustworthy energy‐efficient routing MIMO (TEEM) technique is used by implementing MIMO technique in TEER protocol to isolate malicious nodes and to reduce the fading effects and interference in the network. The performance of ABC‐based trustworthy energy‐efficient MIMO routing (ABC‐TEEM) protocol is analysed. Alive node performance, residual energy, throughput analysis, and pocket loss rate of ABC‐TEEM protocol for WSN are computed and compared with the performance of existing TEEM protocol for various diversity orders.     

Multi‐hop communications in directional CSMA/CA over mmWave WPANs

In this paper, we consider the multi‐hop communications in contention period of medium access control protocol over millimeter‐wave band. A relaying devices selection policy and a grouping algorithm are proposed, and the directional carrier sense multiple access/collision avoidance protocol in the immediate acknowledgement mode for IEEE 802.15.3c is considered under saturation environments. The purpose of this paper is to analyze the effect of using directional antennas and relaying devices in contention period. A sensing region and an exclusive region are computed probabilistically and used in the grouping algorithm. Numerical results show that the narrower radiation beamwidth allows to use a channel more spatially, and the effect of using relaying devices increases as the beamwidth and number of devices increase. Those effects are presented in the throughput and average delay. The obtained results will be used as performance criterion for the multi‐hop communications in millimeter‐wave wireless personal area networks. Copyright © 2015 John Wiley & Sons, Ltd.     

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.