Jan 11, 2013Researchers from the University of Cambridge have formed a new company, known as PervasID, to deliver a "wide-area" passive radio frequency identification solution that it claims is near 100 percent when detecting paper documents and other assets. The system can cover up to a 400-square-meter (4,300-square-foot) area by means of a single EPC Gen 2-compliant ultrahigh-frequency (UHF) RFID reader, and can scale up to accommodate much larger deployments.
The PervasID system, which employs an array of antennas in a widely spaced network known as a distributed antenna system (DAS), has been piloted by the records-management division of Civica UK, a British IT and business services systems-integration firm. This file-tracking system, PervasID reports, is designed to provide a long read range and near 100 percent read rate, at a lower cost than existing systems, since there is a need for only a single reader per up to 400-square-meter space, and because it is easy to install.
Conventional passive UHF RFID systems typically offer a lower useful read range than PervasID's solution, as well as lower reliability, says Sithamparanathan Sabesan, a University of Cambridge researcher and one of the company's cofounders. Read accuracy usually degrades at a distance of about 3 meters (9.8 feet) or more, he explains, and interrogating signals can be cancelled due to reflections, thereby leading to null spots within the radio environment. In the case of the PervasID system, those resulting nulls are eliminated via the use of the DAS network, as well as advanced RF techniques and multiple antennas. This allows wide area interrogation without relying on narrow pinch points.
Initially, the technology was developed by Sabesan and fellow university researchers Michael Crisp, Richard Penty and Ian White, in order to provide an intelligent airport system—called The INtelligent Airport (TINA)—to transmit UHF RFID data via its DAS solution, and to carry other wireless services that might be present at an airport (see UK Researchers Study Distributed Antenna System for Airports). However, since completing that three-year project, which was funded by the United Kingdom’s Engineering and Physical Sciences Research Council (EPSRC), the Cambridge research team began looking into more immediate commercially viable RFID applications, and developed a records-tracking solution to detect the presence of RFID tags on files in such places as medical or legal offices. The technology enables users to know, in real time, in which room (or in which part of a very large room) a file may be located.
With the DAS solution, one RFID controller (reader) feeds four sets of bistatic antennas via coaxial cables. Each set of antennas includes one dedicated for transmitting RF signals and another for receiving them.
During the pilot, one PervasID interrogator was installed within an office in which Civica UK's employees worked—a room measuring 8 meters by 17 meters (26.2 feet by 55.8 feet). The office was furnished with desks on which approximately 100 files filled with pages of paper were stacked in piles of five files apiece. Attached to each file were two passive EPC Gen 2 UHF tags made with Impinj Monza 4 chips. The files were stacked up to five high on the desks, Sabesan says.
Ian Keers, managing director of Civica's Records Management division, comments: "Civica is now actively discussing the technology with potential clients for an installation or pilot of the DAS RFID system hardware and software."
In addition, PervasID is working to offer a version of its system with location functionality, so that PervasID technology could then allow users to learn not only in which room a tagged file was located, but also approximately where within that space.
