Ultra-high frequency (UHF) RFID technology today is being adopted by a variety of applications such as inventory control tracking, race timing, attendee tracking, access control, and more. Several sub-1 GHz wireless technologies are being standardized and developed that operate at a specific frequency within the 902–928 MHz license free ISM bands. However, a significant challenge at this frequency is performance degradation of UHF RFIDs due to RF interference.
A team of researchers at Gyeongsang National University in Korea under Prof. Wang-Sang Lee used the NI AWR Design Environment, specifically Visual System Simulator (VSS) system design software, to evaluate the EMI effects of an RFID signal against the sub 1 GHz wireless communication signal and to analyze the impact of RF interference from a Gaussian frequency-shift keying (GFSK) modulated signal in a passive UHF RFID system.
According to the team, VSS is easy to use and provides detailed descriptions of each element, which helped them to quickly and easily analyze the RFID system. The many useful VSS examples related to recent RF system simulations available through the NI AWR knowledgebase were very helpful, as was the responsive technical support.
To simplify the simulation analysis, RF front-end circuits such as transmit and receive antennas, a bandpass filter, an RF switch for time-division multiplexing (TDD), an amplifier, and a down-conversion mixer, were omitted. To compare the EMI effects of the UHF RFID system, it was assumed that the system was a line-of-sight communication system with an additive white Gaussian noise (AWGN) communication channel.
The reflection characteristics of the environment were not considered. The backscattered RFID and interference signals were reduced by antenna characteristics and the operating distance. The modulation index of the UHF RFID system was 0.8 and the data rate of those signals was 50 kpbs.
Through membership in the AWR University Program, Prof. Lee and his team had access to the complete suite of NI AWR software tools. The intuitiveness of the VSS software and detailed descriptions of each element enabled the team to quickly and easily analyze the RFID system. Additionally, the VSS examples related to recent RF system simulations available through the knowledgebase were very helpful, as was the responsive technical support staff.
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