Passive Radio Frequency Identification Systems Research Articles

A High Throughput Anticollision Protocol to Decrease the Energy Consumption in a Passive RFID System

One of the main existing problems in Radio Frequency Identification (RFID) technology is the tag collision problem. When several tags try to respond to the reader under the coverage of the same reader antenna their messages collide, degrading bandwidth and increasing the number of transmitted bits. An anticollision protocol, based on the classical Binary Tree (BT) protocol, with the ability to decrease the number of bits transmitted by the reader and the tags, is proposed here. Simulations results show that the proposed protocol increases the throughput with respect to other recent state-of-the-art protocols while keeping a low energy consumption of a passive RFID system.

An Energy-Efficient ECC Processor of UHF RFID Tag for Banknote Anti-Counterfeiting

In this paper, we present the design and analysis of an energy-efficient 163-b elliptic curve cryptographic (ECC) processor suitable for passive ultrahigh frequency (UHF) radio frequency identification (RFID) tags that are usable for banknote authentication and anti-counterfeiting. Even partial public key cryptographic functionality has long been thought to consume too much power and to be too slow to be usable in passive UHF RFID systems. Utilizing a low-power design strategy with optimized register file management and an architecture based on the Lopez-Dahab Algorithm, we designed a low-power ECC processor that is used with a modified ECC-DH authentication protocol. The ECC-DH authentication protocol is compatible with the ISO/IEC 18000-63 (“Gen2”) passive UHF RFID protocol. The ECC processor requires 12 145 gate equivalents. The ECC processor consumes 5.04 nJ/b at a frequency of 960 kHz when implemented in a 0.13- $\mu \text{m}$ standard CMOS process. The tag identity authentication function requires 30 600 cycles to complete all scalar multiplication operations. This size, speed, and power of the ECC processor makes it practical to use within a passive UHF RFID tag and achieve up to 1500 banknote authentications per minute, which is sufficient for use in the fastest banknote counting machines.

Analysis and Validation of Active Eavesdropping Attacks in Passive FHSS RFID Systems

In this paper, we present a generalized framework for active eavesdropping in a frequency hopping spread spectrum passive radio frequency identification system. In our model, there exists an adversarial reader who is able to transmit its own continuous wave signal outside the frequency band of the legitimate reader. Due to the fact that under backscatter modulation, the tag cannot distinguish different frequencies and simply sets the impedance in its circuitry to either low or high to reflect a bit of 1 or 0, and the adversarial reader’s received signal is a weighted sum of the response to both its own signal and the legitimate reader’s signal. Using this model, we provide a theoretical analysis of the capability of the adversarial reader in terms of the decoding error probability for slow frequency and fast frequency hopping systems. We derive analytic formulas and conduct experiments using software defined radios that act as the legitimate reader, the adversarial reader, and Intel Wireless Identification Sensing Platform tags with parameters as specified in EPC Gen2. Simulations are also used to validate our findings. We find from the theoretical analysis as well the experimental results that the active eavesdropper can achieve a better decoding error rate than a conventional passive eavesdropper, even in the case that the eavesdropper’s signal is a low power signal.

Backscattering UWB/UHF hybrid solutions for multi-reader multi-tag passive RFID systems

Ultra-wideband (UWB) technology is foreseen as a promising solution to overcome the limits of ultra-high frequency (UHF) techniques toward the development of green radio frequency identification (RFID) systems with low energy consumption and localization capabilities. While UWB techniques have been already employed for active tags, passive tags solutions are more appealing also due to their lower cost. With the fundamental requirement of maintaining backward compatibility in the RFID domain, we propose a hybrid UWB/UHF architecture to improve passive tag identification both in single-reader and multi-reader scenarios. We then develop two hybrid algorithms: the first one exploits the UWB signal to improve ISO/IEC 18000-6C UHF standard, while the other one exploits UWB to enhance a compressive sensing (CS) technique for tag identification in the multi-reader, multi-tag scenario. Both solutions are able to improve success rate and reading speed in the tag identification process and reduce the energy consumption. The multi-reader version of the proposed approaches is based on a cooperative scheme in order to manage reader-tag collisions and reader-reader collisions besides the typical tag-tag collisions. Furthermore, timing synchronization non-idealities are analyzed for the proposed solutions and simulation results reveal the effectiveness of the developed schemes.

Analysis of RFID Based Positioning Technique Using Received Signal Strength and Directional Antenna

Automatic robot navigation is being utilized in many industries for the purpose of high speed work delivery. Color follower, fix path follower robots are current solution to this activities but dynamic path configuration is not possible in these robots. Hence new system proposes effective and fully dynamic path follower robots using RFID and directional antenna. Radio Frequency Identification (RFID) system permits automatic identification of objects with RFID tags using radio waves which have been widely used in mobile robot navigation, localization and mapping both in indoor and outdoor environment. This article presents a navigation strategy for autonomous mobile robot using passive RFID system. Proposed robot system is provided with RFID tag functionality which will load tag number and direction instruction. At some turning point, user will put RF tag, this tag will be read by RF reader which is placed on robot. As per direction instruction robot will change the direction and reach to the destination. Also as per the movement, robot will send its GPS location to PC (Personal Computer) which will be displayed on PC. Hence main goal is to provide more reliable and low energy consumption based indoor positioning system which will be achieved using directional antenna.

Localization of pallets in warehouses using passive RFID system

Warehouse operation has become a critical activity in supply chain. Position information of pallets is important in warehouse management which can enhance the efficiency of pallets picking and sortation. Radio frequency identification (RFID) has been widely used in warehouse for item identifying. Meanwhile, RFID technology also has great potential for pallets localization which is underutilized in warehouse management. RFID-based checking-in and inventory systems have been applied in warehouse management by many enterprises. Localization approach is studied, which is compatible with existing RFID checking-in and inventory systems. A novel RFID localization approach is proposed for pallets checking-in. Phase variation of nearby tags was utilized to estimate the position of added pallets. A novel inventory localization approach combing angle of arrival (AOA) measurement and received signal strength (RSS) is also proposed for pallets inventory. Experiments were carried out using standard UHF passive RFID system. Experimental results show an acceptable localization accuracy which can satisfy the requirement of warehouse management.

Modeling of the Passive UHF RFID Multipath Channel for Tag Read Region Estimation

The estimation of tag read and no-read zones is the most important preliminary planning step in radio-frequency identification (RFID) system installations. Today, in the ultra-high frequency band (UHF: 860–960 MHz), this estimation is based on either a free-space or a simplified multipath channel model for the signal propagation in the wireless link between the interrogator and the tag. Using measurements in a standard multipath indoor environment, this paper proves that recent approaches are not able to estimate tag read regions in a given passive UHF RFID system setup with high reliability. A modified multipath channel model is presented, that considers environmental and setup specific properties as well as an arbitrary number of signal paths to achieve a more accurate estimation. It includes the orientation of the tag antenna and the interrogator antenna, their polarizations and their three-dimensional gain patterns, as well as complex reflection coefficients for the reflected signal paths. The presented model equations are ready to use and are implemented into a flexible, easy-to-use, and easy-to-setup simulation environment with low computing times. It predicts the tag read regions separately for the downlink and the uplink and then combines the results for an overall estimation. The comparison of read region simulations and tag readability measurements shows that the our model delivers a 87.2 % reliability in the prediction of the tag read regions. The results of the estimation can be used to optimize RFID system setups in a way that read regions are maximized.

Quantifying detection performance of a passive low-frequency RFID system in an environmental preference chamber for laying hens

Radio Frequency Identification (RFID) systems are widely used in production livestock systems for identification, traceability assurance, and animal registration. An RFID system was implemented and evaluated for use in a four-compartment, two-tier, environmental preference chamber (EPC) to detect hens transiting between compartments. Eight RFID antennae were located near the passages between compartments and each hen wore an RFID tag on one of its legs. The RFID system’s performance was assessed by determining detection ranges in a controlled test and by comparing the number of entries into and duration in each compartment as detected by the RFID system to manual assessment of recorded video. The RFID system detection range was revealed to cover a radius of approximately 29cm from the antenna, excluding a portion of the compartment furthest from the antenna. During a choice-test study, successful detection rates based on duration of stay in compartments were 91.0±2.6% (mean±SD) for trials with groups of birds, and 85.8±8.0% for trials with individual birds. Based on number of entries into compartments, successful detection rates were 62.6±11.2% for trials with groups of four birds, and 51.3±18.4% for trials with individual birds. Sources of entry misdetection included: (i) RFID tag being out of the detection range during sampling; (ii) conflicts caused by multiple RFID tags within the same detection zone; and (iii) visits of duration less than the RFID antenna scan interval. The delay between hen entry and RFID system detection averaged 42.3±35.7s and 6.4±5.2s in trials with individuals and with groups, respectively. Detection times were within the antenna scanning interval of 15s (a hen entered a compartment and was immediately detected by the next antenna scan) in 60.3% of the events with individuals and 98.1% of the events with groups. Despite the difference between detected and actual entries (P=0.008 [groups]; P=0.05 [individuals]), no significant differences were found between total duration of compartment occupancy over a 24h test period or average compartment visit duration, as calculated from RFID data and video observations. The RFID system was suitable for characterizing the amount of time birds spent in each EPC compartment, but not reliable for determining number of entries into a compartment.

Reduction of Proximity Effects on UHF Passive RFID Systems by Using Tags With Polarization Diversity

A new technique that enables passive ultra high frequency (UHF) radio frequency identification (RFID) tags to be read when they are placed in close proximity in an array is presented. This paper demonstrates that, in a linear tag array with a tag separation of 1 cm, the interaction between the backscattered waves and incident wave causes a significant degradation in tag sensitivity. It is found that the use of tags that have polarization diversity can improve the read performance when they are placed in close proximity to one another compared with conventional linear tags. Two ways of achieving polarization diversity are studied in this paper, namely: 1) using a circularly polarized tag and 2) using a cross-polarized tag pair. Both methods show an improvement in close proximity read performance and it is experimentally demonstrated that by using cross-polarized tag pairs in an array, one achieves on average a 2.6-dB increase in read power margin for a 57-tag array with 1 cm separation compared with using conventional linearly polarized tags.

Passive RFID Tag Anticollision Algorithm for Capture Effect

Capture effect is very common in passive radio frequency identification systems. Even though multiple tags transmit their signals to a reader simultaneously, one of the tags will be successfully identified due to capture effect. However, capture effect may hide some tags. Many existing algorithms that assume no capture effect will miss the hidden tags. In this paper, we extend an existing algorithm to the capture effect environment and propose a novel tag anti-collision algorithm to enhance the efficiency of tag identification. The proposed algorithm adopts an allocation strategy to reduce collision between the hidden tags by capture effect and the other tags. The strategy lets the collided tags resolved in a current cycle immediately. On the other hand, the hidden tags will enter the next cycle. Thus, the resolved tags will not collide with the hidden tags in the next cycle, and the collision will be reduced. The experiment results show that the proposed protocol's identification efficiency outperforms other existing protocols when the occurrence probability of capture effect varies from 0.1 to 0.6.

An Efficient Degradation Particle Swarm Optimization Algorithm for 3D Location in RFID System

With the proliferation of radio frequency identification (RFID) systems, existing two dimensional (2-D) location algorithms cannot meet the manufacturing demand anymore. In this paper, an efficient degradation particle swarm optimization (DPSO) algorithm is proposed to solve the three dimensional (3-D) location problems in passive tag RFID systems. Performance evaluation shows this method can approach the actual target tag position with acceptable deviation and stability which can meet the newly generated production demand.

Dual port temperature sensor tag for passive UHF RFID systems

Purpose – The purpose of this paper is to develop a novel totally passive, wireless temperature sensor tag based on ultra high-frequency (UHF) radio frequency identification (RFID) technology. The temperature-sensing functionality is enabled by using distilled water embedded in the tag antenna substrate. The novel sensor tag is designed to provide wireless temperature readings comparable to a commercial thermocouple thermometer even in environments with high levels of interference, such as reflections. The structure of the novel sensor tag is aimed to increase its usability by minimizing user-created errors and to simplify the measurement procedure. Design/methodology/approach – The sensor tag is based on a dual port sensing concept in which two ports are used to obtain sensor readings. By utilizing two ports instead of one, the effects of environmental interference, tag-reader antenna orientation and distance can be effectively minimized. Two alternative methods of acquiring the sensor reading from the operating characteristics of the two ports are presented and discussed. Findings – Temperature measurements in practical scenarios show that by utilizing the dual port sensing concept, the developed tag produces temperature readings wirelessly which are comparable to readings from a commercial thermocouple thermometer. Research limitations/implications – The concept of dual port sensing was shown and two alternative methods on extracting sensor readings from the differences in the port operating characteristics were introduced and discussed. In this paper, the dual port sensing concept is utilized in creating a temperature sensor tag; however, the same concept can be utilized in a variety of passive wireless sensors based on UHF RFID technology. This enables a new approach in designing accurate, easy to use and easily integrable passive sensors. The dual port sensing concept is in its early stages of development; its accuracy could be improved by developing more advanced data post-processing techniques. Practical implications – The accuracy of a passive dual port UHF RFID-enabled temperature sensor tag is proven to be sufficient in many applications. This indicates that other sensor types utilizing the dual port sensing concept can reach high levels of accuracy as well. Furthermore, the passive RFID-enabled sensors based on the dual port sensing concept are superior in usability versus sensor tags equipped only with a single port. Therefore, dual port sensing concept in passive UHF RFID-enabled sensor tags could make such sensors more attractive commercially and lead to truly widespread ubiquitous sensing and computing. Originality/value – This paper presents a novel passive, wireless temperature sensor tag for UHF RFID systems. The sensor tag utilizes a new structure which allows tight integration of two ports and two tag antennas. The accuracy of the developed tag is confirmed throughout measurements and it is found comparable to the accuracy of commercial thermometers in practical measurement scenarios. Moreover, the paper presents a dual port sensing concept and two readout methods based on the concept which are aimed to increase the accuracy and usability of all kinds of UHF RFID-enabled sensor tags.

Wide Area Passive UHF RFID System Using Antenna Diversity Combined With Phase and Frequency Hopping

This paper presents a long range and effectively error-free ultra high frequency (UHF) radio frequency identification (RFID) interrogation system. The system is based on a novel technique whereby two or more spatially separated transmit and receive antennas are used to enable greatly enhanced tag detection performance over longer distances using antenna diversity combined with frequency and phase hopping. The novel technique is first theoretically modelled using a Rician fading channel. It is shown that conventional RFID systems suffer from multi-path fading resulting in nulls in radio environments. We, for the first time, demonstrate that the nulls can be moved around by varying the phase and frequency of the interrogation signals in a multi-antenna system. As a result, much enhanced coverage can be achieved. A prototype RFID system is built based on an Impinj R2000 transceiver. The demonstrator system shows that the new approach improves the tag detection accuracy from to 100% over a 20 m ×15 m area, compared with a conventional switched multi-antenna RFID system.

A Qualitative Approach to Mobile Robot Navigation Using RFID

Radio Frequency Identification (RFID) system allows automatic identification of items with RFID tags using radio-waves. As the RFID tag has its unique identification number, it is also possible to detect a specific region where the RFID tag lies in. Recently it is widely been used in mobile robot navigation, localization, and mapping both in indoor and outdoor environment. This paper represents a navigation strategy for autonomous mobile robot using passive RFID system. Conventional approaches, such as landmark or dead-reckoning with excessive number of sensors, have complexities in establishing the navigation and localization process. The proposed method satisfies less complexity in navigation strategy as well as estimation of not only the position but also the orientation of the autonomous robot. In this research, polar coordinate system is adopted on the navigation surface where RFID tags are places in a grid with constant displacements. This paper also presents the performance comparisons among various grid architectures through simulation to establish a better solution of the navigation system. In addition, some stationary obstacles are introduced in the navigation environment to satisfy the viability of the navigation process of the autonomous mobile robot.

Wireless Sensor Network and RFID Fusion Approach for Mobile Robot Navigation

There are numerous applications for mobile robots that require relatively high levels of speed and precision. For many systems, these two properties are a tradeoff, as oftentimes increasing the movement speed can mean failing to detect some sensors. This research attempts to create a useful and practical system by combining a wireless sensor network with a passive radio frequency identification system. The sensor network provides fast general navigation in open areas and the radio frequency identification system provides precision navigation near static obstacles. By fusing the data from both systems, we are able to provide fast and accurate navigation for a mobile robot. Additionally, with WSN nodes and passive RFID tag mats, the system infrastructure can be easily installed in existing environments.

Binary Tree Slotted ALOHA for Passive RFID Tag Anticollision

In order to enhance the efficiency of radio frequency identification (RFID) and lower system computational complexity, this paper proposes three novel tag anticollision protocols for passive RFID systems. The three proposed protocols are based on a binary tree slotted ALOHA (BTSA) algorithm. In BTSA, tags are randomly assigned to slots of a frame and if some tags collide in a slot, the collided tags in the slot will be resolved by binary tree splitting while the other tags in the subsequent slots will wait. The three protocols utilize a dynamic, an adaptive, and a splitting method to adjust the frame length to a value close to the number of tags, respectively. For BTSA, the identification efficiency can achieve an optimal value only when the frame length is close to the number of tags. Therefore, the proposed protocols efficiency is close to the optimal value. The advantages of the protocols are that, they do not need the estimation of the number of tags, and their efficiency is not affected by the variance of the number of tags. Computer simulation results show that splitting BTSA's efficiency can achieve 0.425, and the other two protocols efficiencies are about 0.40. Also, the results show that the protocols efficiency curves are nearly horizontal when the number of tags increases from 20 to 4,000.

Interference Helps to Equalize the Read Range and Reduce False Positives of Passive RFID Tags

In various applications of radio frequency identification (RFID) systems, a reader should reliably get the ID of the tags that are within a bounded proximity region, termed the interrogation zone. This gives rise to two types of errors: 1) false negative detections (FNDs), when tags within the intended interrogation zone cannot be read, and 2) false positive detections (FPDs), when tags outside the zone can be read. The detuning effect experienced from the object a tag is attached to exacerbates the occurrence of FND. Solving FNDs by increasing the reader power increases the probability of FPDs for tags outside the zone. Hence, the design of an interrogation zone poses a tradeoff between readability inside versus outside the desired zone. We present a novel method to reduce the probability of FNDs and FPDs and practically equalize the achievable range for tags experiencing detuning. We propose to impose intentional interference on the communication between reader and tag. The expected effects of the proposed method are evaluated using experimental measurements. The results are positive, showing a sharp edge of the interrogation zone and a strong equalization of the range of tuned and detuned tags. Hence, it is concluded that by imposing interference enables the design of well-defined interrogation zones for passive RFID systems.

Energy aware improved least and most significant bit arbitration algorithm for WORM tags

Passive Radio Frequency Identification systems have gained enormous attention and popularity especially after its adoption in time and data critical systems. Theoretically, these systems have the potential to read over 100 tags per second in applications which are well insulated from RF noise. Nevertheless, this may not be the case in practical systems, as tag collision is one of the major deterrents affecting the recognition rate. This paper exhaustively analyses the existing probabilistic, deterministic and hybrid algorithms on collision resolutions. In probabilistic algorithms, tags send their entire ID to the RFID reader in respective slots while tags in deterministic algorithms respond bit by bit based on the RFID reader’s query. To minimize identification delay, tag communication overhead and high energy consumption, a new energy efficient collision resolution strategy named Improved Least and Most Significant Bit Algorithm (LaMSBA) is introduced to effectively singulate a tag and increase the identification efficiency in changing tag population even when the bits in tag ID’s are randomly or uniformly distributed. Extensive simulation studies show that LaMSBA can be chosen as better alternatives for dense time and data critical RFID enabled systems. In addition, M/G/1 Queuing model is suitably identified and the the analytical results concluded that LaMSBA is able to maintain the steady state condition even when Class 1 tags arrive at the rate of 15 tags/second in the reader’s interrogation zone.

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.

Design and Optimization of a CDMA-Based Multi-Reader Passive UHF RFID System for Dense Scenarios

In dense passive radio frequency identification (RFID) systems, code division multiple access (CDMA) techniques can be used to alleviate severe collisions and thus enhance the system performance. However, conventional CDMA techniques are challenging to implement, especially for passive tags due to cost and power constraints. In this paper, we design a CDMA-based multi-reader passive ultra high frequency (UHF) RFID system in which a reader detects only the strongest tag signal and a tag uses Gold codes only on the preamble and the data bits of RN16 without increasing its clock frequency. We present a new communication procedure based on dynamic framed slotted ALOHA (DFSA). In order to optimize the system, we theoretically analyze the system performance in terms of slot capacity and identification rate, and formally show how the code length and the number of readers affect the identification rate. Furthermore, we propose an effective method for tag estimation and frame size adjustment, and validate it via simulations. Through an example, we demonstrate how the analysis-based technique can be used to optimize the system configurations with respect to the number of readers and the number and length of Gold codes.