Ambient FSK Backscatter Communications using LTE Cell Specific Reference Signals

TL;DR

This paper presents a novel ambient backscatter communication system leveraging LTE cell-specific reference signals and FSK modulation, enabling reliable data transmission by introducing artificial Doppler shifts detectable by standard channel estimators.

Contribution

It introduces a new AmBC system utilizing LTE CRS for channel estimation and artificial Doppler shifts for data encoding, validated through simulations and measurements.

Findings

FSK AmBC demonstrates robust performance in fading channels.

Artificial Doppler shifts are effectively tracked by LTE channel estimators.

System validation confirms practical viability of the proposed approach.

Abstract

Long Term Evolution (LTE) signal is ubiquitously present in electromagnetic (EM) background environment, which make it an attractive signal source for the ambient backscatter communications (AmBC). In this paper, we propose a system, in which a backscatter device (BD) introduces artificial Doppler shift to the channel which is larger than the natural Doppler but still small enough such that it can be tracked by the channel estimator at the User Equipment (UE). Channel estimation is done using the downlink cell specific reference signals (CRS) that are present regardless the UE being attached to the network or not. FSK was selected due to its robust operation in a fading channel. We describe the whole AmBC system, use two receivers. Finally, numerical simulations and measurements are provided to validate the proposed FSK AmBC performance.