Millimeter Wave Backscatter

Abstract

Backscatter networks (such as RFID, and WiFi backscatter) are very attractive for IoT applications due to their ultra-low energy consumption. In fact, their required energy to operate is low enough that it can be harvested from the environment without having a battery. However, existing backscatter networks offer very limited data-rates (i.e. at most one Mbps). Hence, despite their energy benefit, their applications are very limited. This paper presents the design of mmTag, a backscatter network which can achieve Gbps data-rates. mmTag achieves this by developing a backscatter technology operating in the mmWave spectrum band. mmWave promises to enable high throughput wireless links by offering massive chunks of high-frequency spectrum. However, to use mmWave frequencies in backscatter networks, we need to address a fundamental challenge: beam alignment. mmWave devices require highly directional antennas with very narrow beams, and communication is possible only when the transmitter's beam is aligned with the receiver's beam. However, existing beam searching techniques require power hungry components, and most importantly require the node to transmit a signal which is not possible for a backscatter device. mmTag solves this problem by building a mmWave backscatter tag which performs beam alignment without using any active component. Finally, we implement mmTag and empirically demonstrate some results.

Next-Generation IoT Devices: Sustainable Eco-Friendly Manufacturing, Energy Harvesting, and Wireless Connectivity

“…However, such a design requires mixing the impinging RF with a local oscillator [142] at each element, which makes the array bulky, power-hungry, and therefore unsuitable for IoT applications. Recently, the structures like Van Atta Arrays have shown great potential for mmWave backscattering (up to 28 GHz) [137], [143], [144], [145]. The idea of Van Atta arrays dates back to 1960 [146].…”

OmniScatter

“…Sensitivity of the backscatter tag is one of the principal metrics of the backscatter communication system, where [17,27,28,37,52,63,74] proposed advanced coding schemes for better sensitivity. Other papers sought to increase coverage with smart relays [40,75], or introduce cross-polarization backscatter tags [42].…”

“…Backscatter is an attractive option for scalability with its ultra-low power operation at tens of uW [72] offering long-term sustainability. In particular, recent advances in mmWave backscatters [7,11,34,42,52] present a great potential for scalability by exploiting the abundant spectrum resource in the mmWave ranging up to 14 GHz (60 GHz band); A bandwidth over two orders of magnitude greater than 26 MHz and 100 MHz in the popular 900 MHz and 2.4 GHz bands, respectively.…”

“…This paper presents OmniScatter, a mmWave back-scatter system with an extreme sensitivity of -115 dBm (Section 3.2), > 20 dB improvement over state-of-the-arts (-90 dBm in [42]). This stems from OmniScatter's unique design that is immune to ambient reflections, while retaining the signal boost capability of the FMCW.…”

Content-agnostic backscatter from thin air

“…In recent years, ambient backscatter has attracted ever-growing attention as it is promising to deliver near zero-power communications for billions of tiny computing devices [18,32,39,41,42,49,54,57,60,63]. Different from traditional radio frequency identification (RFID) communications, it has three distinct features.…”