CellScatter: Efficient Control and Backscatter Communication via Ambient Cellular Signals

Abstract

Due to the continuous traffic of ubiquitous cellular networks and the ultra low-power low-cost characteristics of backscatter communication, cellular backscatter communication is a crucial technology for passive Internet of Things. However, existing cellular backscatter systems suffer from the lack of downlink control ability, low-efficiency modulation, and unreliable demodulation for megabit-rate backscatter transmission. This paper proposes CellScatter to overcome such drawbacks. First, we design a synchronization-and-control module for a CellScatter tag, which exploits cellular reference signals to achieve accurate synchronization and reliable multi-tag control without extra time overhead. Then, we design a single-sideband high-order modulation module to focus the backscatter signal power to the desired band and improve the spectrum utilization efficiency. Furthermore, we establish an explicit model to represent the spectrum-expanded backscatter signal without requiring a high-speed analog-to-digital converter, and derive a closed-form solution for the user equipment to recover the data of the tag at low complexity. We prototype the CellScatter system and evaluate its performance via ambient 4G LTE and 5G NR signals. Experimental results show that CellScatter can achieve 2.24 Mbps backscatter communication within a range of 30 meters, 6.7× lower BER and 33% higher rate than state of the art solutions.