Radio Frequency Identification Tag Identification Research Articles

SAW RFID Tag Spatial Division Multiple Access Based on 3D Reflector Response Localization Using a Wideband Holographic Approach

Surface acoustic wave (SAW) radio-frequency identification (RFID) has high potential for industrial applications, where automated identification and localization of assets represent the backbone of process controlling and logistics. However, in situations where multiple tags are simultaneously interrogated, the response patterns corresponding to the hard-coded reflectors are prone to overlap, preventing their association with the corresponding tags and, hence, the correct tag decoding. Identification and localization of multiple SAW RFID tags are addressed in this work under this challenging effect, known as collision, with a multi-antenna mobile robot-based synthetic aperture approach. Using the estimation of the spatial probability density functions of the SAW tag reflectors over a given interrogation aperture, the received impulse responses can be resolved in three dimensions and clustered with respect to their estimated locations. The performance of the proposed approach to associate and localize the signals from multiple tags was evaluated theoretically and experimentally.

A Dynamic Multi-ary Query Tree Protocol for Passive RFID Anti-collision

In this paper, a dynamic multi-ary query tree (DMQT) anti-collision protocol for Radio Frequency Identification (RFID) systems is proposed for large scale passive RFID tag identification. The proposed DMQT protocol is based on an iterative process between the reader and tags which identifies the position of collision bits through map commands and dynamically encodes them to optimize slots allocation through query commands. In this way, the DMQT completely eliminates empty slots and greatly reduces collision slots, which in turn reduces the identification time and energy costs. In addition and differently to other known protocols, the DMQT does not need to estimate the number of tags, reducing the protocol implementation complexity and eliminating the uncertainty caused by the estimation algorithm. A numerical analysis shows that DMQT has better performance than other algorithms for a number of tags larger than 300. Meanwhile, when the number of tags is 2000 and the tag identity (ID) length is 128 bits, the total identification time is 2.58 s and the average energy cost for a tag identification is 1.2 mJ, which are 16.9% and 10.4% less than those of state-of-the-art algorithms, respectively. In addition, a DMQT extension based on ACK command has also been presented to deal with capture effect and avoid missing identification.

Chipless tag detection and recognition based on frequency modulated continuous wave

Towards the commercialization of chipless radio frequency identification (RFID) systems, there are still some pressing issues. The detection and identification of chipless RFID tags are mainly realized by a vector network analyzer (VNA). In practice, this equipment is costly and not convenient enough. This paper designs a maneuverable detection model based on frequency modulated continuous wave (FMCW), the detection target is an 8-bit chipless tag based on a variable-side-length spiral resonance unit and decodes the amplitude and phase information. On this basis, signal processing is performed on the generated amplitude and phase based on the Savitzky-Golay (SG) smoothing algorithm, and then the simulation data of HFSS is compared with ADS model data by the matrix pencil method (MPM). The results show that the proposed FMCW-based method can be effectively implemented in wireless communication, providing a new solution for flexible and inexpensive chipless tag detection and recognition.

An Efficient Q -Algorithm for RFID Tag Anticollision

In large-scale Internet of Things (IoT) applications, tags are attached to items, and users use a radiofrequency identification (RFID) reader to quickly identify tags and obtain the corresponding item information. Since multiple tags share the same channel to communicate with the reader, when they respond simultaneously, tag collision will occur, and the reader cannot successfully obtain the information from the tag. To cope with the tag collision problem, ultrahigh frequency (UHF) RFID standard EPC G1 Gen2 specifies an anticollision protocol to identify a large number of RFID tags in an efficient way. The Q -algorithm has attracted much more attention as the efficiency of an EPC C1 Gen2-based RFID system can be significantly improved by only a slight adjustment to the algorithm. In this paper, we propose a novel Q -algorithm for RFID tag identification, namely, HTEQ, which optimizes the time efficiency of an EPC C1 Gen2-based RFID system to the utmost limit. Extensive simulations verify that our proposed HTEQ is exceptionally expeditious compared to other algorithms, which promises it to be competitive in large-scale IoT environments.

A knowledge-based Query Tree with Shortcutting and Couple-Resolution for RFID tag identification

In Radio Frequency Identification (RFID) systems, the reader identifies tags through communications over a shared wireless channel. However, when multiple tags transmit their IDs simultaneously, their signals collide, thereby prolonging the identification delay. However, in some applications, the RFID system has the availability of a database containing the IDs of all the tags that may possibly appear. The present study proposes a novel knowledge-based Query Tree with Shortcutting and Couple Resolution (QTSC) protocol for reducing the identification delay in RFID systems with such a database. In the proposed protocol, a knowledge-based query tree is first constructed to store the queries required to identify all the possible tags in the database. Then, at identifying appearing tags, the tags actually appear among possible tags, shortcutting and couple-resolution techniques are employed to skip redundant queries in the query tree and transmit two ID prefixes simultaneously within the same slot, respectively. The simulation results show that compared to the existing knowledge-based protocols, Knowledge Query Tree (KQT) and Heuristic Query Tree (HQT) protocols, QTSC reduces the identification delay by 60.5% and 39.0%, respectively.

Channel-Quality Aware RFID Tag Identification Algorithm to Accommodate the Varying Channel Quality of IoT Environment

Radio Frequency Identification (RFID) technique is broadly adopted as the automated identification system for the Internet of Things (IoT). Many RFID anti-collision algorithms were proposed to accelerate the tag identification process. However, they misjudged some unreadable slots which were due to collision instead of the bad channel condition, causing low bandwidth usage. This study proposes the Channel-quality Aware Query Tree algorithm (CAQT) to improve the identification performance in an error-prone channel environment. CAQT has three novel features: (1) it estimates the channel quality continuously and statistically in the rapidly changing channel quality environment; (2) it asks the tag for retransmission or to split the collide tags based on the channel quality; (3) the number of the groups which it splits tags is based on the estimated number of tags collide in current slot. The simulation results show that CAQT uses less than 31% slots compared with the conventional algorithms. The simulation results also demonstrate that CAQT provides enhanced performance when the channel quality is varying especially in outdoor environment, for example, ticket checking for railway or subway system.

IoT-Linked Integrated NFC and Dual Band UHF/2.45 GHz RFID Reader Antenna Scheme

This research proposes a system board of integrated antenna scheme of near-field communication (NFC) and dual band ultra-high frequency (UHF, 920–925 MHz)/2.45 GHz radio frequency identification (RFID) reader antennas for Internet of Things (IoT) applications. The integrated antenna scheme is capable of simultaneous execution of NFC and UHF RFID functions whereby the NFC and UHF RFID modules, which are serially connected to a microcontroller with Wi-Fi module (NodeMCU), read the universal identification (UID) of NFC and UHF RFID tags. The data are then forwarded to a cloud server via Internet of Things (IoT) and are viewable on smartphones using Blynk mobile application via IoT. To realize the optimal antenna design, simulations were carried out using CST Studio Suite. Prototype antennas were subsequently fabricated and integrated into the system board for IoT-linked near- and far-field communication. The simulation and measured results are in good agreement. The NFC reader antenna resonates at 13.56 MHz, and the dual band UHF/2.45 GHz RFID reader antenna achieves the 920–925 MHz and microwave (MW) bands with high isolation. The novelty of the proposed integrated NFC and UHF RFID antenna scheme lies in the use of cloud technology to store real-time and archival data, in place of traditional servers. The integrated antenna scheme could achieve the NFC, UHF, and MW frequency bands, rendering it ideal for IoT applications.

A Time- and Energy-Aware Collision Tree Protocol for Efficient Large-Scale RFID Tag Identification

Being able to provide a relatively easy and inexpensive way to collect data, portable readers have gained increasing popularity in wide-ranging RFID applications. In order to maximize the reader’s battery life, efficient tag identification protocols are of paramount importance in large-scale passive radio frequency identification (RFID) systems. This paper proposes a time- and energy-aware protocol based on $M$ -ary collision tree (MCT) for efficient RFID tag identification. Thanks to Manchester encoding, the proposed MCT protocol recursively divides colliding tags into $M$ subsets with at least two nonempty ones according to the information of $\log _2 M$ colliding bits. Through the new MCT recognition process, MCT can effectively identify all the tags within its reading range. Theoretic analysis demonstrates that it takes the proposed MCT protocol fewer numbers of collision slots and message bits to identify all the tags, which reduces not only the identification time but also the energy cost. Simulation results are also presented to show that compared with other benchmark works, the proposed MCT protocol is able to reduce the average identification time and energy cost by at least 16.12% and 15.73%, respectively.

RFID Tag Acquisition Via Compressed Sensing: Fixed vs. Random Signature Assignment

We introduce a novel scheme to perform radio frequency identification (RFID) with compressed sensing techniques. The proposed scheme allows quick and reliable identification of several RFID tags, even at low signal-to-noise ratio. Contrary to the widely used frame slotted ALOHA (FSA) protocol, the tags activated by a reader deliberately respond simultaneously with their assigned signature during the acquisition phase; collisions are regarded as beneficial rather than destructive. The signatures are drawn from a huge signature pool, and the set of signatures that is assigned to the activated tags is very small compared to the total signature count. This introduces sparsity to the acquisition phase which, in turn, allows formulation of the acquisition as a compressed sensing measurement. Furthermore, our formulation permits the usage of a low-complexity approximate message passing algorithm for compressed sensing recovery. We compare two realizations of the compressed sensing-based approach to the FSA protocol. The first performs fixed signature assignment - this enables very quick identification but sacrifices flexibility. The second performs random signature assignment - this reduces the identification speed but provides flexibility. A comparison via simulation shows that both compressed sensing-based approaches significantly outperform FSA in terms of identification speed and robustness to noise.

Dynamic M-ary QT Algorithm to Improve the Performance of RFID Tag Identification

Radio-frequency identification (RFID) is the wireless non-contact use of radiofrequency electromagnetic fields to transfer data, for the purposes of automatically identifying and tracking tags attached to objects. Most important technical issue in radio frequency identification (RFID) is to correctly and quickly recognize a number of tag IDs in the reader’s communication range. At present, a reasonable solution is the

A Collecting Collision Tree Protocol for RFID Tag Identification with Capture Effect

Multitag identification is one of the main advantages of the radio frequency identification (RFID) system. In the RFID system, the capture effect often happens in the real environment. When the capture effect occurs, the reader will not completely identify the tags in its scope. In many RFID applications, to get the real-time number of tags, the reader identifies the tags repeatedly. In these cases, the tag in the reader's scope is a staying tag or an arriving tag. The reader already stores the IDs of all staying tags, so it can just verify the existence of these tags to rapidly identify them. As a result, the reader can spend the main time in recognizing arriving tags. To cope with the capture effect and identify staying tags rapidly, this paper presents a collecting collision tree protocol for RFID tag identification with capture effect (CCT). In CCT, a collecting mechanism is adopted and a lot of staying tags can be recognized in a slot. What is more, the reader can identify all tags in its range when the capture effect happens. Finally, various analysis and simulation results show that CCT outperforms the existing algorithms significantly.

Methods of selection and identification of RFID tags

Radio frequency identification (RFID) is a technology with numerous benefits in applications where objects have to be identified automatically. However, cost, fragile tags, collision and reading errors are some of issues to be concerned with in an RFID implementation. Mainly, this paper proposes a method for tag identification and a method for the selection of the binary codes to program on the tags in order to facilitate the identification process. For the identification method a heuristic based on Hamming distance is developed where the basic idea is to utilize the information obtained in consecutive read attempts to help identify a tag. For the selection method three models based on Hamming distance are also developed which strive to find the set with the greatest dissimilarity among the codes. Computer simulations are performed to verify the validity of the proposed methods.

A Slot Allocated Blocking Anti-Collision Algorithm for RFID Tag Identification

In many Radio Frequency Identification (RFID) applications, the reader recognizes the tags within its scope repeatedly. For these applications, some algorithms such as the adaptive query splitting algorithm (AQS) and the novel semi-blocking AQS (SBA) were proposed. In these algorithms, a staying tag retransmits its ID to the reader to be identified, even though the ID of the tag is stored in the reader’s memory. When the length of tag ID is long, the reader consumes a long time to identify the staying tags. To overcome this deficiency, we propose a slot allocated blocking anti-collision algorithm (SABA). In SABA, the reader assigns a unique slot to each tag in its range by using a slot allocation mechanism. Based on the allocated slot, each staying tag only replies a short data to the reader in the identification process. As a result, the amount of data transmitted by the staying tags is reduced greatly and the identification rate of the reader is improved effectively. The identification rate and the data amount transmitted by tags of SABA are analyzed theoretically and verified by various simulations. The simulation and analysis results show that the performance of SABA is superior to the existing algorithms significantly.

A Method for Identifying Multiple RFID Tags in High Electromagnetic Interference Environments

Radio frequency identification (RFID) plays an important role in warehouse management. Unfortunately, the normal work environment in warehouses has electromagnetic interferences that cause reading failures. Failures can also be caused by other circumstances, such as collision between reading attempts, tag type, and hardware problems. Rather than propose a hardware-based approach, we propose a method based on information processing. We propose the points assignment (PA) method for the identification of multiple RFID tags based on the Hamming distances. The basic idea is to use all the readings, even if they contain errors. The method allows groups of tags to be identified in high-interference environments, where other methods have great difficulty for achieving error-free readings. The performance of the proposed method is compared with two other methods, showing that the PA achieves zero errors with fewer readings, and that it has more consistent performance as interference increases.

Determination of optimal frame sizes in framed slotted ALOHA

The primary task of radio-frequency identification (RFID) readers is to identify multiple objects as quickly and reliably as possible with minimal power consumption and computation. An optimisation problem related to the selection of appropriate frame sizes for the framed slotted ALOHA protocol, commonly used in passive RFID tag identification systems, is considered. The fundamental question concerning this issue is: what frame size is most suitable for identifying as many tags as possible in a given time? More formally, what is the optimal value for frame sizes in the sense that the probability of successful identification is maximised? Thus far, many research results related to this problem have been reported in the literature, but most are either suboptimal or empirical. Through asymptotic analysis, it is shown that the optimal frame size is approximately given by N/ln 2 for N tags.

Modified M-ary QT Algorithm to Improve the Performance of the Anti-collision Protocol for RFID Tag Identification

The Radio Frequency Identification (RFID) system is a newemerging technology used to identify a tag attached to an object. To make RFID systems practical, the cost of RFIDtags is very important. Further, an interrogator should be able to identify thenumber of tags in the reading range in a short time. The most important technical issue in radio frequency identification (RFID) is to correctly and quickly recognize the number of tag IDs in the reader’s communication range. Unlike the probabilistic RFID tag identification schemes, a query tree(QT)-based protocol guarantees the identification of all the tags, where the distribution of tag IDs is assumed to be uniform. In this paper, we proposed an extended M-ary QT protocol, which effectively reduces unnecessary query-response cycles by using a non-sequential m-bit recognition method. The simulation results show that the proposed scheme significantly outperforms M-ary QT schemes in terms of identification time, efficiency and communications overhead.

A Novel RFID Tag Identification Protocol: Adaptive $$n$$ n -Resolution and $$k$$ 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 $$k$$ 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).

A Site-Specific Stochastic Propagation Model for Passive UHF RFID

This letter proposes a computationally inexpensive, site-specific propagation model, useful in coverage evaluation of radio frequency identification (RFID) networks with passive tags. The parameters of a Rice distribution for each point in the volume of interest are computed using site-specific approximations that address overall space geometry, materials, and polarization. The probability of successful identification of passive RFID tags is calculated. Coverage statistics and performance evaluation of complex RFID networks can be quickly conducted. Experimental results at the UHF regime corroborate the accuracy of the model.

A semi-blocking algorithm on adaptive query splitting for RFID tag identification

Radio frequency identification (RFID) is a promising wireless technology for using tiny, remotely powered chips as identifiers. The number of RFID applications is rapidly increasing because RFID technology is convenient, fast, and contactless. However, collisions occur when multiple tags simultaneously transmit their IDs. Therefore, an efficient anti-collision algorithm is needed to accelerate tag identification. In some applications, the reader may repeatedly identify staying tags, which constantly exist in the reader's range. The adaptive query splitting algorithm (AQS) was proposed for reserving information obtained from the last identification process to enable rapid re-identification of staying tags. However, since AQS is a non-blocking algorithm that allows newly arriving tags to use the slots reserved for staying tags, collisions among them are problematic. Thus, semi-blocking AQS (SBA) proposed in this study is designed to reduce the collisions between arriving tags and staying tags by applying a semi-blocking technique in which only a minority of arriving tags use the slots reserved for staying tags. By counting the number of minor arriving tags, SBA estimates the number of unrecognized arriving tags and generates proper queries to minimize their collisions. The identification delay of SBA is analyzed, and simulation results show that SBA significantly outperforms AQS.

An Anti-Collision Algorithm for Applications with Massive RFID Tags

Anti-collision is a key technology in systems and applications in which Radio Frequency Identification (RFID) is used since it determines the efficiency of RFID tag identification. Although binary-tree search algorithms can effectively resolve collisions, they may not be very efficient in systems with a large number of RFID tags. In this paper, we propose a new flat-tree anti-collision algorithm and show that the proposed algorithm is more suitable for resolving collisions involving a massive number of RFID tags. Through analysis and experiment, we show that the flat-tree algorithm outperforms the binary-tree search algorithms when the number of RFID tags reaches a massive scale, i.e., exceeds a certain number.