Decision Fusion Rules in Ambient Backscatter Wireless Sensor Networks

Ambient backscatter (AmBC) communications capitalize on ambient radio-frequency (RF) signals to enable communications among ultra-low-power devices, thus representing a promising cost-effective solution for wireless sensor networks in the Internet of Things. In this paper, we study the scenario where single-antenna AmBC sensors are employed to perform decision fusion over multiple-access fading channels. Specifically, AmBC sensors detect the presence/absence of a phenomenon of interest and transmit their decisions to a multiple-antenna fusion center reader (FCR), by reflecting part of an incident RF ambient signal. In this scenario, we derive fusion rules at the FCR by considering both the cases of instantaneous and statistical channel state information, as well as their corresponding low-complexity alternatives. Numerical simulation results are provided to compare the proposed fusion rules and highlight the relevant trends.