First Real-Time Detection of Ambient Backscatters using Uplink Sounding Reference Signals of a Commercial 4G Smartphone

TL;DR

This paper introduces a novel real-time ambient backscatter detection system using uplink signals from smartphones, demonstrating high detection probability in indoor and outdoor environments with a commercial 4G device.

Contribution

It is the first to utilize uplink signals for ambient backscatter detection, expanding the potential for zero-energy IoT devices in cellular networks.

Findings

Over 90% detection probability indoors at 3 meters distance

Successful detection behind walls and obstacles

Prototype implementation with commercial hardware

Abstract

Recently, cellular Ambient Backscattering has been proposed for cellular networks. Up to now an Ambient backscatter device, called zero-energy device or tag, broadcasted its message by backscattering ambient downlink waves from the closest Base Station (BS) according to a predefined pattern. A tag was detected by smartphones nearby. This paper presents, for the first time, a novel ambient backscatter communication system exploiting uplink ambient waves from smartphones instead of downlink waves. In this novel system, a BS connected to a smartphone monitors the uplink pilot signals and detects TAGs in proximity. The proposed system is implemented and tested with one prototype of TAG, a commercial off-the shelf 4G smartphone and a 4G Software Defined Radio (SDR) BS. Indoor and outdoor experiments were conducted to assess the proposed technique. These very preliminary experiments exhibit a promising potential. In indoor, a detection probability of more than 90% has been achieved without false alarm when the TAG was 3 meters from the UE, and the BS 20 meters away of them, behind walls and obstacles.