BLE-Backscatter: Ultralow-Power IoT Nodes Compatible With Bluetooth 4.0 Low Energy (BLE) Smartphones and Tablets

TLDR

Backscatter communication offers power and complexity advantages for IoT devices, yet it has been limited by the need for specialized RFID readers. This work demonstrates how to design backscatter signals that are compatible with the ubiquitous Bluetooth 4.0 low‑energy chipsets in smartphones and tablets. A microcontroller‑based BLE‑Backscatter tag modulates band‑pass frequency‑shift keying at 1 Mb/s, using the standard BLE advertising channels and the existing Bluetooth stack without any hardware, firmware, or software modifications. The tag achieves up to 13 m range to an unmodified iPad Mini or nRF51822 PC and up to 30 m between a CW carrier source and the tag, while consuming only 1.56 nJ/b—over six times less power than the lowest‑power commercial Bluetooth transmitters.

Abstract

Backscatter communication promises significant power and complexity advantages for Internet of Things devices such as radio frequency identification (RFID) tags and wireless sensor nodes. One perceived disadvantage of backscatter communication has been the requirement for specialized hardware such as RFID readers to receive backscatter signals. In this paper, we show how backscatter signals can be designed for compatibility with the Bluetooth 4.0 low energy (BLE) chipsets already present in billions of smart phones and tablets. We present a prototype microcontroller-based "BLE-Backscatter" tag that produces bandpass frequency-shift keying modulation at 1 Mb/s, enabling compatibility with conventional BLE advertising channels. Using a +23-dBm equivalent isotropically radiated power continuous wave (CW) carrier source, we demonstrate a range of up to 13 m between the tag and an unmodified Apple iPad Mini as well as a PC with the Nordic Semiconductor nRF51822 chipset. With the tag 1 m from the receiver, we demonstrate a range of up to 30 m between the CW carrier source and the tag. In both cases, the existing Bluetooth stack was used, with no modifications whatsoever to hardware, firmware, or software. The backscatter tag consumes only 1.56 nJ/b, over 6× less than the lowest power commercial Bluetooth transmitters.