Section: New Results

Flexible Radio Front-End

RFID tag-to-tag communication

RFID is a well-known technique for wireless authentication. Usually, such a system only consists on a reader communicating with one or several tags. The concept of passive RFID tag-to-tag communications has been recently introduced and opens new promising perspectives, especially in the field of Internet-of-Things. In this work, a simulation framework was proposed as a new tool allowing the performance evaluation of tag-to-tag radio links. The modeling takes into consideration the external source supplying the communication between tags, radiating characteristics of tag antennas, and reception system aspects. Performance results are expressed in terms of Bit Error Rate (BER) with respect to the distance between the tags and the position of the energy source relative to the position of the two tags [36], [35].

Optimization of waveforms for energy harvesting

We have studied the incidence of the modulation scheme as well as the input power on the RF to DC rectifier conversion efficiency for an energy harvesting system based on radiowaves. A commercial energy harvesting (EH) P21XXCSR-EVB evaluation board from Powercast Corporation is used as measurement target and several waveforms are employed to evaluate the rectification efficiency. With a continuous wave as reference, QPSK, QAM and OFDM waveforms usage demonstrates that digital modulated signals can lead to a better efficiency. Thus, by selecting a high peak to average power ratio (PAPR), and under certain conditions, the performance of the energy harvesting circuit is enhanced [30].