Spatial Stream Backscatter Using Commodity WiFi

Zhao, Jia; Gong, Wei; Liu, Jiangchuan

doi:10.1145/3210240.3210329

Cited by 100 publications

(47 citation statements)

References 26 publications

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“…Backscatter technology is the most energy-efficient wireless communication link [5,15,[35][36][37]. A typical backscatter system consists of two parts: a reader and one or multiple backscatter tags.…”

Section: Background 21 Backscatter Communicationmentioning

confidence: 99%

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Millimeter Wave Backscatter

Mazaheri

Chen

Abari

2020

Proceedings of the 19th ACM Workshop on Hot Topics in Networks

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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.

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Section: Background 21 Backscatter Communicationmentioning

confidence: 99%

“…However, existing RFID tags enable throughput of less than a Mbps. Recent work have proposed designing WiFi-based backscatter tags [4,16,37]. Their goal is to design backscatter tags which can communicate to WiFi devices.…”

Section: Related Workmentioning

confidence: 99%

Millimeter Wave Backscatter

Mazaheri

Chen

Abari

2020

Proceedings of the 19th ACM Workshop on Hot Topics in Networks

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“…BST allows the BackCom physical layer for concurrent transmissions from multiple tags with the help of intra-bit multiplexing of OOK signals. Similarly, the MOXcatter system is suggested for multiplexing using a spatial stream BackCom with off-the-shelf WiFi devices [69]. The coding techniques for accommodating a large amount of data on backscattered signals are elaborated below.…”

Section: Backcom Signal Processing Aspectmentioning

confidence: 99%

Backscatter Communications: Inception of the Battery-Free Era—A Comprehensive Survey

Memon

Saxena

Roy³

et al. 2019

Electronics

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The ever increasing proliferation of wireless objects and consistent connectivity demands are creating significant challenges for battery-constrained wireless devices. The vision of massive IoT, involving billions of smart objects to be connected to the cellular network, needs to address the problem of uninterrupted power consumption while taking advantage of emerging high-frequency 5G communications. The problem of limited battery power motivates us to utilize radio frequency (RF) signals as the energy source for battery-free communications in next-generation wireless networks. Backscatter communication (BackCom) makes it possible to harvest energy from incident RF signals and reflect back parts of the same signals while modulating the data. Ambient BackCom (Amb-BackCom) is a type of BackCom that can harvest energy from nearby WiFi, TV, and cellular RF signals to modulate information. The objective of this article is to review BackCom as a solution to the limited battery life problem and enable future battery-free communications for combating the energy issues for devices in emerging wireless networks. We first highlight the energy constraint in existing wireless communications. We then investigate BackCom as a practical solution to the limited battery life problem. Subsequently, in order to take the advantages of omnipresent radio waves, we elaborate BackCom tag architecture and various types of BackCom. To understand encoding and data extraction, we demonstrate signal processing aspects that cover channel coding, interference, decoding, and signal detection schemes. Moreover, we also describe BackCom communication modes, modulation schemes, and multiple access techniques to accommodate maximum users with high throughput. Similarly, to mitigate the increased network energy, adequate data and power transfer schemes for BackCom are elaborated, in addition to reliability, security, and range extension. Finally, we highlight BackCom applications with existing research challenges and future directions for next-generation 5G wireless networks.

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“…This approach has been utilized to co-exist with WiFi in [11], [23] and with LoRA [24]. In [25], [26] a multi-hop protocol was proposed, in which each of the backscatter devices in the multi-hop-chain between the transmitter and receiver shift the frequency further. In [18], [19], partial shift of the spectrum was proposed for Orthogonal Frequency Division Multiplexed (OFDM) ambient signals, such that the scattered component would appear in the null carriers of the ambient signal.…”

Section: Introductionmentioning

confidence: 99%

Polarization Conversion-Based Ambient Backscatter System

et al. 2020

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In Ambient Backscatter Communications (AmBC), a backscatter device communicates by modulating the ambient radio frequency (RF) signal impinging at its antenna. In many cases, the system setup is bi-static such that the receiver and the ambient signal source are separated in space. This configuration suffers from the direct path interference problem. The direct signal component can be several orders of magnitude stronger than the scattered one. This imposes a challenge for the receiver that needs to have high dynamic range in order not to lose the scattered signal component to the quantization noise. In this paper, we propose a novel AmBC system concept, in which a polarization conversion between the direct and scattered path is introduced at the backscatter device and exploited at the dual polarization based receiver antenna to mitigate the direct path interference. The proposed system is agnostic to the ambient signal source characteristics as long as it uses linearly polarized antennas. The backscatter device changes the polarization from linear to circular. The receiver antenna is a circularly polarized patch antenna with a 180°-hybrid to obtain the difference between the left-and right-hand polarized fields. Ideally, this receiver antenna and 180°-hybrid combination would completely remove linearly polarized direct path and reflected components. In this paper, we propose a robust design that can mitigate the direct path signal power more than 25 dB despite nonidealities in the antenna manufacturing. INDEX TERMS Polarization conversion, ambient backscatter communication.

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Spatial Stream Backscatter Using Commodity WiFi

Cited by 100 publications

References 26 publications

Millimeter Wave Backscatter

Millimeter Wave Backscatter

Backscatter Communications: Inception of the Battery-Free Era—A Comprehensive Survey

Polarization Conversion-Based Ambient Backscatter System

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