Wireless technology has become an integral part of our everyday lives. With each new generation of new tech, it almost seems expected that devices become wireless. The gradual introduction of the Internet of things (IoT) is a great example. Many devices that previously required manual interaction can now be monitored and altered through wireless communication links. In addition, devices are becoming less demanding on power consumption, helping to extend their operating life in the field and reduce their carbon footprint. Hoping to continue this trend of lower power consumption and more connectivity, some companies are beginning to look towards a technology known as backscattering.
Backscatter is the term for a system that can harvest energy from a wireless signal, modulate the received RF signal, and reflect it back toward the source it originally came from. It is similar to RFID (radio frequency identification) in many ways used in transportation, asset management, animal tracking, and work badges used to access office buildings. RFID systems consist of a transceiver, an antenna, and a transponder where the antenna and transponder are generally one device known as the RFID tag, and the transceiver is the device requesting and receiving the information on the RFID tag. RFID systems can be active or passive.
On the other hand, a backscatter communication system is completely passive. In it, a reader is used to produce a continuous wave sinusoidal signal. Next, a passive device harvests this energy and uses it to modulate the sinusoid signal. This signal is then reflected back to the reader with the information encoded in it but at a much lower power. This entire process is known as backscattering.
A further advancement of this technology is known as ambient backscatter. Ambient backscattering operates off the same principles. However, instead of the reader sending a continuous sinusoidal wave to a sensor to power it, it utilizes signals already in the wireless spectrum. This can be Wi-Fi, FM radio, television, or cell phone signals. These transmission sources (with the exception of Wi-Fi) can be many miles away and still provide a strong enough RF signal to provide power to a passive device. Additionally, these signals themselves can still be modulated and reflected back to an awaiting receiver.
As eluded to earlier, this technology holds great value for IoT devices and remote sensors. Currently, many of these devices are battery-powered and, as a result, have to be serviced occasionally. This can be troublesome for remote devices and devices located in hard-to-reach places (anywhere high up). Backscattering technology can potentially offer a method for sensors to operate without batteries in locations where power cannot be readily provided.
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