Efficient LTE Backscatter with Uncontrolled Ambient Traffic

Ambient LTE backscatter is a promising way to enable ubiquitous wireless communication with ultra-low power and cost. However, modulation in previous LTE backscatter systems relies heavily on the original data (content) of the signals. They either demodulate tag data using an additional receiver to provide the content of the excitation or modulate on a few predefined reference signals in random ambient LTE traffic.This paper presents CABLTE, a content-agnostic backscatter system that efficiently utilizes uncontrolled LTE PHY resources for backscatter communication using a single receiver. Our system is superior to prior work in two aspects: 1) Using one receiver to obtain tag data makes CABLTE more practical in real-world applications, and 2) Efficient modulation on LTE PYH resources improves the data rate of backscatter communication. To obtain the tag data without knowing the ambient content, we design a checksum-based codeword translation method. We also propose a customized channel estimation scheme and a signal identification component in the backscatter system to ensure our accurate modulation and demodulation. Extensive experiments show that our CABLTE provides maximum tag throughput of 22 kbps, which is 3.67x higher than the content-agnostic system CAB and even 1.38x higher than the content-based system SyncLTE.