Link Budget and Enhanced Communication Distance for Ambient Internet of Things

 Abstract: Backscatter communication, a key technology for ambient Internet of Things (ambient IoT), will play an important role in connecting everything for beyond 5G (B5G) and 6G systems. One open challenge for backscatter communications is that the signals suffer a round-trip path loss so that the communication distance is short, which motivates our present work. In this paper, we first calculate communication distance upper bounds for both uplink and downlink by measuring the tag sensitivity and reflection coefficient. It is found that the activation voltage of the envelope detection diode of the downlink tag is the main factor limiting the backscatter communication distance. Based on this analysis, we then propose to implement a low-noise amplifier (LNA) module before the envelope detection at the tag to enhance the incident signal strength. Our experimental results on the hardware platform show that our method can increase the downlink communication range by nearly 20 m.

Keywords: ambient IoT (AIoT); B5G; backscatter communication; link budget; low-noise amplifier (LNA); Release 19; tag chip sensitivity; upper bounds