Christian Floerkemeier

Issues with RFID Usage in Ubiquitous Computing Applications

Radio Frequency Identification (RFID) has recently received a lot of attention as an augmentation technology in the ubiquitous computing domain. In this paper we present various sources of error in passive RFID systems, which can make the reliable operation of RFID augmented applications a challenge. To illustrate these sources of error, we equipped playing cards with RFID tags and measured the performance of the RFID system during the different stages of a typical card game. The paper also shows how appropriate system design can help to deal with the imperfections associated with RFID.

RFID Application Development With the Accada Middleware Platform

The proliferation of radio frequency identification (RFID) systems in application domains such as supply chain management requires an IT infrastructure that provides RFID device and data management and supports application development. In this paper, we discuss these application requirements in detail. We also contend that the characteristics of passive RFID technology introduce constraints that are unique to the development of middleware for the RFID domain. These constraints include the occurrence of false negative reads, tag memory variations, the heterogeneous reader landscape, and the limited communication bandwidth available to RFID readers. To address these constraints and the application requirements for filtered and aggregated RFID data, we developed Accada, an open source RFID platform. This paper shows that the Accada implementation, which is based on a set of specifications developed by the EPCglobal community and a number of extensions, such as the surrogate concept and the virtual tag memory service, addresses the majority of the application requirements and limitations of passive RFID technology.

Bayesian Transmission Strategy for Framed ALOHA Based RFID Protocols

Transmission control strategies can increase the throughput of the shared wireless channel and thus accelerate the identification of large RFID tag populations. In this paper, we present a Bayesian strategy that minimizes the response time to changes in the number of RFID tags transmitting by updating the tag number estimate after each slot in an ALOHA frame. If the current frame size is no longer considered to be optimal, our control strategy aborts the current frame and triggers the start of a new frame size. The transmission control strategy is evaluated with the help of a scalable RFID simulation engine that implements the ISO 18000-6 C protocol and that supports different pathloss, fading, capture, and tag mobility models. Our evaluation shows that the Bayesian transmission strategy has a higher throughput than other approaches that only update the estimate at the end of the frame. The evaluation also shows that our Bayesian approach outperforms the Q algorithm specified in ISO 18000-6 Part C at the expense of a significant amount of computations.

Scanning with a purpose: supporting the fair information principles in RFID protocols

Todays RFID protocols that govern the communication between RFID readers and tags are solely optimized for performance, but fail to address consumer privacy concerns by appropriately supporting the fair information practices. In this paper we propose a feature set that future privacy-aware RFID protocols should include in order to support the fair information principles at the lowest possible level – the air interface between readers and tags – and demonstrate that the performance impact of such an extension would be within acceptable limits. We also outline how this feature set would allow consumer interest groups and privacy-concerned individuals to judge whether an RFID reader deployment complies with the corresponding regulations through the use of a watchdog tag.

Transmission control scheme for fast RFID object identification

There are a variety of approaches to improve the speed at which large RFID tag populations are being identified. In this paper, we present a transmission control strategy for a common class of RFID multiple access schemes. It builds on earlier work on Bayesian broadcast strategies, but has been adapted to address characteristics of the RFID domain. It has been designed for framed ALOHA and it makes no restrictive assumptions about the distribution of the number of tags in the range of the interrogator. Experimental evidence and simulation results are presented showing that the proposed transmission control scheme performs well in practise when compared to existing approaches

Technology, Standards, and Real-World Deployments of the EPC Network

The EPC Network is a global RFID data sharing infrastructure based on standards that are built around the Electronic Product Code (EPC), an unambiguous numbering scheme for the designation of physical goods. The authors present the fundamental concepts and applications of the EPC Network, its integration with enterprise systems, and its functionality for data exchange between organizations in the supply chain.

Comparison of transmission schemes for framed ALOHA based RFID protocols

The performance of RFID anti-collision protocols that are based on framed ALOHA depends on a transmission scheme that controls access to the shared channel. In this paper, we outline the characteristics of the RFID domain that impact the performance of such transmission schemes and compare four different transmission strategies. A novel technique introduced in this paper that recursively estimates the backlog on a slot-by-slot basis exhibits a superior performance in our simulations. The results also illustrate that our implementation of the Q algorithm proposed in (EPCglobal, 2005) only performs well, if the frame size changes are restricted to incremental updates

Low-Cost, Ubiquitous RFID-Tag-Antenna-Based Sensing

Radio-frequency identification (RFID) has been well established as an effective technology for track and trace applications. In this paper, we go beyond the ID in RFID, and discuss the potential for RFID tags to be used as low-cost sensors by mapping a change in some physical parameter of interest to a controlled change in RFID tag antenna electrical properties. We will also show that it is possible to design the tag antenna to suffer a permanent change in case of violation of a critical threshold in the parameter of interest thereby creating a low-cost threshold sensing mechanism. This can be achieved by inducing controlled changes to the tag antenna geometry parameters or to the antenna boundary conditions, in effect creating a nonelectric memory to monitor state. After identifying the application space for which this class of sensing is well suited, we present details into the design and testing of three different kinds of sensors based on this sensing paradigm. We demonstrate how we use this concept to sense displacements, temperature thresholds, and fluid levels. We will show that RFID-tag-antenna-based sensing has the potential to revolutionize application domains in which there is a need for low-cost, long-lasting, ubiquitous sensors.

Towards tag antenna based sensing - An RFID displacement sensor

Displacements can be used as indicators of structural health and are measured by commercially available sensors that need to be accurate and cost effective. In this paper, we examine a technique to utilize a UHF RFID tag antenna as a displacement sensor by mapping structural deformation to a change in RFID tag characteristics. We evaluate how changes in two different parameters, a) tag backscatter power and b) minimum reader transmit power required for RFID chip activation, can be mapped to structural deformation. The theoretical principles of sensor development are first discussed followed by a presentation of the results of experimentation. It is demonstrated that the sensor is sensitive to displacements for a dynamic range of 40 mm.

RFIDSim—A Physical and Logical Layer Simulation Engine for Passive RFID

Radio-frequency identification (RFID) poses a number of research challenges, such as interference mitigation, throughput optimization and security over the RF channel. A number of new approaches to address these issues have been proposed recently, but due to the highly integrated nature of passive RFID tags, it is difficult to evaluate them in real-world scenarios. In this paper, we present an RFID simulation engine, RFIDSim, which implements the ISO 18000-6C communication protocol and supports pathloss, fading, backscatter, capture, and tag mobility models. This paper also shows that our implementation of RFIDSim that relies on a discrete event simulator can be used to simulate large populations featuring thousands of RFID tags. RFIDSim also simulates the deep fades that lead to frequent power losses of the battery-less RFID tags by modeling the multipath effects statistically.