First Experimental Ambient Backscatter Communication Using a Compact Reconfigurable Tag Antenna

Abstract

Ambient backscatter communications have emerged as a promising technology for a sustainable development of the Internet of Things (IoT). In such system, a radio frequency (RF) tag can transmit data to a receiver without battery and without generating any new RF wave, just by backscattering the incident RF wave originated by an ambient RF source. The simplest tag is a dipole that is either in an absorbing mode or in reflecting mode to send "0" or "1", and thus leads to a modulation order of 2. Previous solutions to reach higher modulation order, so as to achieve higher data rate, are based on antenna arrays. However, such solutions are not suitable for connected objects, due to their sizes. In this paper, for the first time, we propose a new tag that uses a compact antenna with reconfigurable radiation patterns to provide a high modulation order. We present experimental bit error rate measurements obtained with an experimental test-bed and two tag antennas, both providing 4 states and thus being able to convey 2 bits per symbol. These measurements show that the performance improves with increasing number of receive antennas, and lead to the conclusion that a tag antenna with low cross-correlations between reconfigurable radiation patterns is suitable for backscattering applications in IoT.