Position estimation of RFID-based sensors using SAW compressive receivers

Wireless data acquisition and data fusion in medical and environmental applications is mainly based on additional information like the position of the sensor device. An accurate and easy to implement method for wireless position estimation of RFID devices is described in this paper. For RFID communication and data transmission, the tags operate within the 13.56 MHz ISM-band with a standardized protocol defined in ISO 14443. The RFID-tag position estimation is done by transmitting linear chirp signals from the RFID tag to base stations on RF frequencies. The chirp signals are generated by SAW devices which are triggered by a low power consumption pulse generator based on an avalanche transistor. The performance of position estimation under AWGN conditions was simulated and compared with common methods. An improvement in the mean square position error in the range of the chirp compression gain was found.