Physical Layer Security in Multi-Tag Ambient Backscatter Communications – Jamming vs. Cooperation

Abstract

In this paper, we study on two different strategies - jamming and cooperation - for improving physical layer security in multi-tag ambient backscatter communications, which utilize existing radio frequency source. First of all, we propose a jamming-based multi-tag scheduling method, which selects a tag for data transmission and another tag(s) for artificial noise generation, in order to give a harmful impact to an eavesdropper. Next, we propose a cooperation-based multi-tag scheduling method, which selects a tag for data transmission and another tag(s) for cooperative transmission (the same data) in order to be helpful to a receiver. Through extensive simulations, we evaluate both strategies in terms of bit error rate and secrecy rate. Finally, we provide a guideline which strategy is better to apply for given environments depending on the total number of tags, channel gains between tags and the receiver, and the number of scheduled tags for jamming or cooperation.