Physical Layer Security Improvement Using Artificial Noise-Aided Tag Scheduling in Ambient Backscatter Communication Systems

In this paper, we propose an artificial noise-aided tag scheduling (ANTS) scheme in order to enhance physical layer security in ambient backscatter communications (ABCs), which utilize existing radio frequency (RF) signals such as TV, FM radio, Wi-Fi, and so on. In more detail, we first select the best tag based on the channel gain between a tag and a reader and then select another tag for generating artificial noise affecting an eavesdropper. Consequently, we propose a scheduling criterion to choose both information and artificial noise tags. In addition, we apply a successive interference cancellation (SIC) technique at the reader in order to eliminate the interference from the artificial noise tag. The simulation results show that our proposed ANTS scheme can obtain a better secrecy rate as the channel gain between the tag and the receiver increases and the number of tags increases. Moreover, when the number of tags is sufficiently large, the proposed ANTS scheme significantly outperforms the conventional scheme in terms of average secrecy rate.