Experiment on Threshold in Ambient Backscatter Communication with Amplitude Modulation

An ambient backscatter communication is typically realized by adopting an Amplitude Modulation (AM) due to its simplicity. Specifically, a low-power tag changes the amplitude of an outgoing backscattered signal to carry its data; a receiver averages the received signal over time and compares the averaged signal strength with a pre-defined threshold. Due to the dynamicity of wireless channels, the initial configuration of a threshold becomes invalid after some time. However, the reconfiguration of the threshold causes network overhead, which degrades communication capacity. Thus, we must investigate a reconfiguration period for the higher capacity of the backscatter system. However, there is little work on investigating the threshold of the backscatter communication. In this paper, we investigate the threshold for an AM-based backscatter communication through experiments. Specifically, we investigate a validity duration of a threshold according to topology and a type of ambient RF signal. Through the experimental results, we notice that the validity duration is affected by several factors and suggest the guideline for configuring the threshold.