Kin Seong Leong

The reader collision problem in RFID systems

In a multi-reader environment, RFID system performance will be limited by the reader collision problem. RFID readers use different channels to minimise collision. However, with limited channels, the in-channel collision will happen. Using a path loss model, this paper predicts the safe distance between the readers before collisions occur in a same channel. This paper also explores the complication caused by the introduction of Listen Before Talk (LBT) in the European Regulation, makes suggestions on how reader collision problems and LBT effects can be minimised

Synchronization of RFID readers for dense RFID reader environments

For a dense RFID reader deployment, such as in warehouse RFID deployment, where hundreds of antennas are positioned in a building, the interference between all these readers must be studied carefully to avoid severe reader collisions. Strict RFID regulations and standards have been imposed, trying to address the problem of reader collision and also the problem of RFID devices interfering with other devices operating in nearby frequency bands. However, these guidelines and regulations are not entirely friendly for dense RFID reader deployment, in some cases it is not possible to have a feasible RFID system while adhering to these regulations. Hence, this paper proposes the synchronization of RFID readers, to enable successful dense RFID reader deployment. A case study targeted at European operations is presented in this paper to visualise the actual synchronization of RFID readers in real life applications. Some fine-tuning methods are also suggested to further improve the performance of readers in a high reader density population area

Operational considerations in simulation and deployment of RFID systems

Large-scale radio frequency identification (RFID) deployment is needed for efficient item identification in supply chains. To reduce cost and save time, simulations are often carried out before actual implementation, especially when RFID is used in regions in which strict regulations and standards must be adhered to. However, due to the unpredictable environmental effects on radio propagation simulation, simple results can be misleading and questions have been raised over the validity of many wireless simulations. This paper reviews, from the point of RFID antenna deployment, the sources of error in wireless simulations reported in some publications. Also, this paper offers important EMC information relevant to RFID system deployment

A small passive UHF RFID tag for livestock identification

RFID has its many applications, one use of this technology is for livestock identification. Animals such as cattle and sheep are tagged for purposes such as disease control, breeding management and also stock management. In this paper, a small passive RFID tag that can be attached to an animals ear and operating at UHF is presented. This paper covers the theoretical design including simulations and the practical implementation of this tag. Significant results obtained from simulations and laboratory testing of an animal ear tag are included in this paper.

Investigation of RF cable effect on RFID tag antenna impedance measurement

The performance of a passive radio frequency identification (RFID) tag depends on the antenna, the chip efficiency of the tag, and also on the matching between the antenna and the chip. The design of the tag antenna often involves the measurement of its impedance. There is no literature which explicitly discusses the measuring methods of the performance of an RFID tag antenna. The closest literature on the measurement of small antennas is either antenna on a mobile handset, mobile radio or antenna in a 50 Omega system. This paper investigates the RF cable effect on the measurement of the RFID tag antenna impedance. Measurement results obtained through several different RF cables are compared with simulation results. Discussions on minimizing measurement error and on how measurement of antenna impedance can assist the design of tag antenna are presented.

Miniaturization of dual frequency RFID antenna with high frequency ratio

We have presented a novel design for dual frequency RFID antenna with high frequency ratio. This antenna works well in both the HF and UHF bands for RFID operation with a single feed. Comparisons between the new design and the previous design are made and the new design is shown to be less than half of the size of the previous design while offering almost the same performance. A functioning dual frequency RFID tag proves that having a dual frequency RFID system is feasible. Although no dual frequency RFID chip is available at the moment, we hope that this successful design of a compact dual frequency RFID antenna will catalyze the development of a dual frequency RFID chip.

Dense RFID Reader Deployment in Europe using Synchronization

For a dense RFID reader deployment, such as in a warehouse, where hundreds of readers will be positioned in a building, the interference between all these readers must be studied carefully to avoid disruption of operations. Strict RFID regulations and standards have been imposed, trying to address the problem of reader collision and also the problem of RFID devices interfering with other devices operating in the same and nearby frequency bands. However, these guidelines and regulations are not entirely friendly for dense RFID reader deployment; in some cases it is not possible to have a feasible RFID system while adhering to these regulations. Hence, this paper proposes the synchronization of RFID readers to enable successful dense RFID reader deployment. A case study targeted at European operations is presented in this paper to illustrate the actual synchronization of RFID readers in real applications. Some fine-tuning methods are also suggested to further improve the performance of readers in a high reader density population area.

Analysis of constraints in small UHF RFID tag

Rapid growth of the application of the radio frequency identification (RFID) technology to object identification has lead to a demand for compact, reliable and inexpensive RFID tags of good read range. Matching between tag antenna and chip impedances for maximum power transfer then becomes very important. Constraints on impedance matching in tags that derive from the reactive elements of the chip and antenna impedances are investigated. Following the analysis, a successful small UHF RFID tag design is presented.

Investigation on the deployment of HF and UHF RFID tag in livestock identification

This paper presents the design of an HF and a UHF tag design that can be used in livestock HF and UHF RFID system. Laboratory testing indicated that both HF and UHF systems have the potential to be used as livestock RFID system. Both HF and UHF systems using ISO 18000 Part 3 (HF) and ISO 18000 Part 6 (UHF) offer the livestock industry the ability to read multiple tags in the race at the same time. Actual field testing will be carried out in the future before large scale deployment is carried out.

Small UHF RFID Label Antenna Design and Limitations

Radio Frequency Identification (RFID) is emerging as an unrivalled contender for automatic object identification technology, its adoption being driven primarily by the potential cost savings in the application of the technology to supply chain management [1]. In general RFID system components include RFID labels, Interrogators (transceivers) and backend control and data collection systems [2]. The mass utilization of RFID technology is hindered by the cost of RFID labels. The cost of producing a label can be separated into IC design, IC manufacture, antenna manufacture, antenna and IC assembly, and packaging. Significant barriers to reducing the cost are the lack of a streamlined process for attaching a RFID label antennas to RFID ICs (about 0.25 mm in size) and the cost of manufacturing antennas, which currently cost around 3 4 US cents per label. Hence this paper focuses on low cost passive RFID labels with the aim of reducing passive labels costs.