Sensitivity and distance based performance analysis for batteryless tags with transmit beamforming and ambient backscattering

Ambient backscatter is a new green technology for Internet of Things (IoT) that utilizes surrounding wireless signals to enable batteryless devices to communicate with other devices. The battery-free devices first harvest energy from ambient wireless signals and then backscatter the signals for communications. Clearly, sensitivity and distance are two important parameters for system performance. However, most existing studies on ambient backscatter communication systems do not consider the impact of the sensitivity of the energy-harvesting nodes and the distances between these devices. In this paper, we first provide a literature review for ambient communication technology and then take sensitivity and distance as two key parameters and investigate the sensitivity and distance based performance for ambient backscatter communication systems. Specifically, we establish the mathematical model based on distances between transceivers and backscattering nodes, extract a parameter that can differentiate the direct path and the backscattering path, evaluate the effects of transmit beamforming, design an energy detector for the reader, and analyze the outage probability of energy harvesting at the tag and the bit error rate (BER) at the reader. Simulations are then provided to corroborate the proposed studies.