Feasibility of backscatter RFID systems on the human body

In this contribution, the author examines the feasibility of on-body backscatter radio frequency identification (RFID) systems in the ultra high frequency range. Four different on-body RFID systems are investigated operating monopoles or patch antennas at 900 MHz or 2.45 GHz. The systems' feasibility is analyzed by means of on-body channel measurements in a realistic test environment. The measured channel transfer functions allow to evaluate if enough power is available for a reliable backscatter communication. This evaluation is done with the aid of outage probabilities in the forward link and the backward link of the systems. Using these probabilities, the on-body systems prove feasible when using state-of-the-art reader and transponder chips. In particular, the use of semi-passive RFID transponder chips leads to a reliable performance in the systems' forward links. The robust performance of the systems' backward links is clearly shown for the 900 MHz monopole antenna configuration, while the limitations in the backward links of the other systems have to be overcome by the use of a second reader unit on the person's back. The novel feasibility analysis presented here allows to examine each system parameter individually and thus leads to reliable and robust backscatter RFID systems.