A double layer stacked patch antenna with a size of 200×200×48mm3 is proposed in this investigation. To achieve a broad CP bandwidth that can cover universal UHF RFID applications (840-960MHz), a slot loaded circular patch antenna fed by an L-shaped probe is designed as the lower layer (main patch), while the top layer (parasitic patch) is a simple circular patch loaded with a cross-slot of dissimilar arm lengths. Besides demonstrating a broad 10-dB return loss bandwidth of 16% (823-966MHz) and a CP bandwidth (3-dB axial ratio) of 14.0% (837-963MHz), the proposed antenna also yields maximum gain and minimum radiation efficiency of 8.8dBic and 85%, respectively, across the universal UHF RFID bands.

Radio Frequency Identifications (RFID) are useful low-cost devices for identification or authentication systems through wireless communication. The ownership of the RFID tag is frequently changed in the life cycle of the tag, it may fall in to the hands of a malicious adversary. The privacy problem in this situation is studied in the RFID ownership transfer protocol. However, almost all previous works provide only heuristic analysis and many protocols are broken. Elkhiyaoui et al. defined the security model for RFID ownership transfer protocols and proposed the detailed security proof to their protocol, but we show that their protocol does not provide enough privacy and cover the realistic attack. We investigate a suitable security model for RFID ownership transfer protocols and provide a new provably secure RFID ownership transfer protocol.

In many radio frequency identification (RFID) applications, the reader identifies the tags in its scope repeatedly. For these applications, many algorithms, such as an adaptive binary splitting algorithm (ABS), a single resolution blocking ABS (SRB), a pair resolution blocking ABS (PRB) and a dynamic blocking ABS (DBA) have been proposed. All these algorithms require the staying tags to reply with their IDs to be recognized by the reader. However, the IDs of the staying tags are stored in the reader in the last identification round. The reader can verify the existence of these tags when identifying them. Thus, we propose an anti-collision algorithm with short reply for RFID tag identification (ACSR). In ACSR, each staying tag emits a short reply to indicate its continued existence. Therefore, the data amount transmitted by staying tags is reduced significantly. The identification rate of ACSR is analyzed in this paper. Finally, simulation and analysis results show that ACSR greatly outperforms ABS, SRB and DBA in terms of the identification rate and average amount of data transmitted by a tag.

In this paper, a threshold-based I-Q diversity combining scheme for ultra-high frequency (UHF) radio frequency identification (RFID) readers with a quadrature receiver is proposed in the aspect of improving the tag detection performance. In addition, the performance of the proposed scheme is evaluated as the closed-form expressions. In particular, its statistical characteristics are detailed and its performance is compared to that of conventional schemes over independent and identically distributed Rician fading conditions in terms of average signal-to-noise ratio (SNR), bit error rate (BER), and the average number of required combining process. Numerical results indicate that the proposed scheme enables processing power control through threshold control while meeting the required quality of service compared to conventional schemes.

Secure authentication of low cost Radio Frequency Identification (RFID) tag with limited resources is a big challenge, especially when we simultaneously consider anonymity, un-traceability, and forward secrecy. The popularity of Internet of Things (IoT) further amplifies this challenge, as we should authenticate these mobile tags in the partial-distributed-server environments. In this paper, we propose an RFID authentication scheme in the partial-distributed-server environments. The proposed scheme owns excellent performance in terms of computational complexity and scalability as well as security properties.

At Eurocrypt 2011, Kiltz et al. presented two efficient authentication protocols for resource-constrained devices such as radio-frequency identification tags. Kiltz et al. proved that their protocols were provably secure against active attackers. However, they did not refer to the security against man-in-the-middle (MIM) attackers. In this paper, we analyze the security of the protocols against the MIM attacks and reveal the vulnerabilities. More concretely, we propose MIM attacks on them and evaluate authentication rounds required in these attacks precisely. We assume that the tag and reader share a 2l-bit secret key. The expected number of authentication rounds to recover the secret information in the first and second protocol is at most 2l+2 and 4l+4, respectively. These attacks do not contradict the proof of security since the MIM attack is located outside the attack model that Kiltz et al. considered.

We present a dynamic key generation method, KeyQ, for establishing shared secret keys in EPCglobal Generation 2 (Gen2) compliant systems. Widespread adoption of Gen2 technologies has increased the need for protecting communications in these systems. The highly constrained resources on Gen2 tags limit the usability of traditional key distribution techniques. Dynamic key generation provides a secure method to protect communications with limited key distribution requirements. Our KeyQ method dynamically generates fresh secret keys based on the Gen2 adaptive Q algorithm. We show that the KeyQ method generates fresh and unique secret keys that cannot be predicted with probability greater than 10-250 when the number of tags exceeds 100.

This paper describes experiments on passive Multiple-Input Multiple-Output (MIMO) transmission with load modulation. PIN diodes are used as the variable impedance element at the tag side to realize multi-level modulation. The results indicate that the transmission rate of passive MIMO is up to 2 times higher than that of Single-Input Single-Output (SISO) with the same transmission power when the distance between the reader and the tag is 0.5m. Also, when the distance is 1m, MIMO offers up to 1.7 times higher transmission rate than SISO. These results indicate that passive MIMO offers high-speed data transmission even when the distance is doubled.

This paper designs tag antennas to satisfy three key goals: mounting on very small objects, extending the reading range with planar structures, and maintaining stable performance on various materials. First, the size of the tag is reduced up to 17% compared to the half-wavelength dipole without a large reduction in bandwidth and efficiency by introducing an inductively coupled feed structure. Second, the reading range is increased to 1.68 times that of the reference dipole tags while maintaining the planar structure using circular polarization characteristics. Finally, a stable reading range is achieved with a deviation in the reading range of only 30% of that of commercial tags on various objects by employing the capacitively-loaded and T-matching network.

We present the relationship between privacy definitions for Radio Frequency Identification (RFID) authentication protocols. The security model is necessary for ensuring security or privacy, but many researchers present different privacy concepts for RFID authentication and the technical relationship among them is unclear. We reconsider the zero-knowledge based privacy proposed by Deng et al. at ESORICS 2010 and show that this privacy is equivalent to indistinguishability based privacy proposed by Juels and Weis. We also provide the implication and separation between these privacy definitions and the simulation based privacy proposed by Paise and Vaudenay at AsiaCCS 2008 based on the public verifiability of the communication message.

In recent years, there has been rapid developments in radio-frequency identification (RFID) systems, and their industrial applications include logistics management, automatic object identification, access and parking management, etc. Moreover, RFID systems have also been introduced for the management of medical instruments in medical applications to improve the quality of medical services. In recent years, the combination of such a system with a biological monitoring system through permanent implantation in the human body has been suggested to reduce malpractice events and ameliorate the patient suffering. This paper presents an implantable RFID tag antenna design that can match the conjugate impedance of most integrated circuit (IC) chips (9.3-j55.2Ω at 2.45GHz. The proposed antenna can be injected into the human body through a biological syringe, owing to its compact size of 9.3mm × 1.0mm × 1.0mm. The input impedance, transmission coefficient, and received power are simulated by a finite element method (FEM). A three-layered phantom is used to confirm antenna performance.

This paper introduces a radio frequency identification (RFID) tag for urination detection. The proposed tag is embedded into paper diapers in order to detect the patient's urination immediately. For this tag, we designed an RFID tag antenna at 950MHz, which matches the impedance of the associated integrated circuit (IC) chip. In addition, we calculate the antenna characteristics and measure the reflection coefficient (S11) and radiation pattern of the antenna. The results show that this system can be used to detect urination.

Despite the improvement of the accuracy of RFID readers, there are still erroneous readings such as missed reads and ghost reads. In this letter, we propose two effective models, a Bayesian inference-based decision model and a path-based detection model, to increase the accuracy of RFID data cleaning in RFID based supply chain management. In addition, the maximum entropy model is introduced for determining the value of sliding window size. Experiment results validate the performance of the proposed method and show that it is able to clean raw RFID data with a higher accuracy.

Cardinality estimation schemes of Radio Frequency IDentification (RFID) tags using Framed Slotted ALOHA (FSA) based protocol are studied in this paper. Not as same as previous estimation schemes, we consider tag cardinality estimation problem under not only detection errors but also capture effect, where a tag's IDentity (ID) might not be detected even in a singleton slot, while it might be identified even in a collision slot due to the fading of wireless channels. Maximum Likelihood (ML) approach is utilized for the estimation of the detection error probability, the capture effect probability, and the tag cardinality. The performance of the proposed method is evaluated under different system parameters via computer simulations to show the method's effectiveness comparing to other conventional approaches.

A variety of ubiquitous computing devices, such as radio frequency identification (RFID) and wireless sensor network (WSN), are generating huge and significant events that should be rapidly processed for business excellence. In this paper, we describe how complex event processing (CEP) technology can be applied to ubiquitous process management based on context-awareness. To address the issue, we propose a method for context-aware event processing using event processing language (EPL) statement. Specifically, the semantics of a situation drive the transformation of EPL statement templates into executable EPL statements. The proposed method is implemented in the domain of ubiquitous cold chain logistics management. With the proposed method, context-aware event processing can be realized to enhance business performance and excellence in ubiquitous computing environments.

The cryptographic algorithm called INCrypt32 is a MAC algorithm to authenticate participants, RFID cards and readers, in HID Global's iCLASS systems. HID's iCLASS cards are widely used contactless smart cards for physical access control. Although INCrypt32 is a heart of the security of HID's iCLASS systems, its security has not been evaluated yet since the specification has not been open to public. In this paper, we reveal the specification of INCrypt32 by reverse-engineering iCLASS cards and investigate the security of INCrypt32 with respect to the cryptographic sense. This result is the first work to describe the details of INCrypt32 and the possibility of a secret key (64-bit) recovery in our attack environments. 242 MAC queries are required in the real environment using secure communication protocols. But the required number of MAC queries decreases to 218 if MAC quires for chosen messages with arbitrary length can be requested.

In this paper, effects of the parasite elements on an antenna impedance of a UHF RFID tag put on a high impedance surface (HIS) are experimentally studied in detail. It is shown that small parasite elements on a mushroom HIS structure can help to recover a mismatch of the impedance and this impedance recovery is brought by an in-phase frequency shift of the HIS due to a mutual coupling between the HIS and the parasite elements. The technique is applied to a commercial 953 MHz band RFID tag inlet antenna on a 53-cell HIS with the total dimension of 125751.5 mm3 and it is demonstrated that the impedance mismatch is successfully recovered and the tag operates with a reading range of 3 m even on a 2003002 mm3 aluminum plate.

Radio frequency identification (RFID) system has gained attention as a new identification source that achieves a ubiquitous environment. Each RFID tag has a unique ID and is attached to an object. A user reads the unique ID of an RFID tag by using RFID readers and obtains the information on the object. One of the important technologies that use the RFID systems is the position estimation of RFID tags. Position estimation means estimating the location of the object with the RFID tag. Acquiring the location information of the RFID tag can be very useful. If a user can know the position of the RFID tag, the position estimation can be applied to a navigation system for walkers. In this paper, we propose a new position estimation method named Swift Communication Range Recognition (S-CRR) as an extended improvement on previous CRR that shortens the estimation delay. In this method, the position of an RFID tag is estimated by selecting the communication area model that corresponds to its boundary angles. We evaluated its performance by experiments and simulations of the RFID system. As the results, we found that S-CRR can estimate the position of an RFID tag comparatively accurately and quickly.

The radio frequency identification (RFID) system has attracting attention as a new identification source that achieves a ubiquitous environment. Each RFID tag has a unique ID code, and is attached on an object whose information it contains. A user reads the unique ID code using RFID readers and obtains information about the object. One of the important applications of RFID technology is the indoor position estimation of RFID tags. It can be applied to navigation systems for people in complex buildings. In this paper, we propose an effective position estimation method named Broad-type Multi-Sensing-Range (B-MSR) method to improve the estimation error of the conventional methods using sensor model. A new reader antenna with two flexible antenna elements is introduced into B-MSR. The distance between two flexible antenna elements can be adjusted. Thus, two kinds of system parameters can be controlled, the distance between two antenna elements and the transmission power of the RFID reader. In this paper, four sensing ranges are settled by controlling the values of two parameters. The performance evaluation shows four characteristics of B-MSR. Firstly, it reduces the initial estimation error. Secondly, it reduces the moving distance. Thirdly, it reduces the number of different sensing points. Fourthly, it shortens the required estimation time.

In this paper, an improved GPS/RFID integration method based on Sequential Iterated Reduced Sigma Point Kalman Filter (SIRSPKF) is proposed for vehicle navigation applications. It is applied to improve the accuracy, reliability and availability of satellite positioning in the areas where the satellite visibility is limited. An RFID system is employed to assist the GPS system in achieving high accuracy positioning. Further, to reduce the measurement noise and decrease the computational complexity caused by the integrated GPS/RFID, SIRSPKF is investigated as the dominant filter for the proposed integration. Performances and computational complexities of different integration scenarios with different filters are compared in this paper. A field experiment shows that both accuracy and availability of positioning can be improved significantly by this low-cost GPS/RFID integration method with the reduced computational load.