To develop test procedures for evaluating the impact on RFID systems of interference generated by other wireless devices
While radio frequency identification (RFID) has a broad range of applications, this project focuses on those that are relevant to homeland security, such as tracking cargo and people at U.S. borders. In particular, we are developing test procedures to evaluate the impact on RFID of interference generated by other wireless systems. Because RFID systems operate in shared frequency bands, they are susceptible to interference generated by other wireless systems. Of interest is to what degree are RFID systems affected by such interference, and how should they be tested for these effects.
A variety of RFID technologies are available differing in the frequencies at which they operate and the type of tag which is queried. These characteristics, in turn, affect power requirements, read range, and suitability for various environments. Most systems operate at one of the following frequencies: 125 kHz (LF), 13.56 MHz (HF), 900 MHz (UHF), or 2.4 GHz. Active tags contain a power source (e.g., battery) and permit higher read ranges and/or lower reader power. Passive tags, on the other hand, draw power from the incident electromagnetic waves of the reader and, hence, are lower in cost. The initial phase of this project will address 900 MHz UHF RFID systems with passive tags.
Wireless applications that operate license-free in the 900 MHz industrial, scientific and medical (ISM) band include supervisory control and data acquisition (SCADA), industrial automation, building automation and control, wireless sensor networks, and consumer devices (e.g., cordless telephones, wireless speakers, baby monitors). In the U.S., most such systems utilize frequency hopping spread spectrum over 902-928 MHz.
To assess the impact of wireless device transmissions on RFID performance, we will utilize a configurable frequency hopping source that generates an FSK-modulated signal in the 902-928 MHz band and will serve as a generalized interference source. The interferer will be positioned at a given distance from an RFID reader interrogating a passive tag. Tag reading success rate and throughput will be measured while the interferer is emitting at various interferer transmission power levels and interferer-reader distances. Such measurements will be conducted for 2-3 different reader systems and various tags.
The resulting test procedures and measurement analysis can be used to develop usage guidelines for passive UHF RFID systems in the presence of co-channel wireless devices.
- Identified a generalized, configurable interference generator for the 900 MHz ISM band (January 2009).
- Testing of interference generator (underway).
Emerging & Mobile Network Technologies Group