Turbocharging ambient backscatter communication

Abstract

Communication primitives such as coding and multiple antenna processing have provided significant benefits for traditional wireless systems. Existing designs, however, consume significant power and computational resources, and hence cannot be run on low complexity, power constrained backscatter devices. This paper makes two main contributions: (1) we introduce the first multi-antenna cancellation design that operates on backscatter devices while retaining a small form factor and power footprint, (2) we introduce a novel coding mechanism that enables long range communication as well as concurrent transmissions and can be decoded on backscatter devices. We build hardware prototypes of the above designs that can be powered solely using harvested energy from TV and solar sources. The results show that our designs provide benefits for both RFID and ambient backscatter systems: they enable RFID tags to communicate directly with each other at distances of tens of meters and through multiple walls. They also increase the communication rate and range achieved by ambient backscatter systems by 100X and 40X respectively. We believe that this paper represents a substantial leap in the capabilities of backscatter communication.

Retro-VLC

“…The technique has been primarily taken by RFID tags [11]. Recently Wi-Fi [13] and TV-based [18,22] systems employed and advanced this techniques as well. Our Retro-VLC system employs a similar idea to achieve low-energy design and further shares the same principle with [13,18,22], i.e.…”

“…Recently Wi-Fi [13] and TV-based [18,22] systems employed and advanced this techniques as well. Our Retro-VLC system employs a similar idea to achieve low-energy design and further shares the same principle with [13,18,22], i.e. using analog components and circuits for extreme energy-efficiency.…”

“…In addition, unlike other backscattering systems that would require intensive tricks and overhead to achieve fullduplex due to their shared antenna and front-end design [3,5,8], Retro-VLC can easily achieve duplex communication. Furthermore, the scattering nature of these backscattering systems tends to expose their transmissions to a wide area, leaving a good chance for side readers to overhear the information [13,18,22]. By contrast, ViTag relies on visible light, which implies eavesdroppers are discernible.…”

“…Inspired by recent work on backscattering communication systems [10,22], we avoid using power-intensive LEDs on the ViTag for the uplink communication. Rather, we choose to backscatter the incoming light from the externally-powered illuminating LED of the ViReader.…”

Laissez-Faire

“…Code Division Multiple Access (CDMA) is another approach for enabling concurrent transmission for backscatter sensors [12, 15, 17]. Here, each sensor exploits an orthogonal code for encoding data where each bit is converted to a long PN sequence (hundreds of bits in length).…”