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takyon [soylentnews.org] writes:

Backscatter Radio at Gigabit Speeds [ieee.org]

Backscatter radios encode data in reflected signals to offer wireless communications that consume as little energy as possible—but they can be limited by poor data rates. Now scientists at Nokia Bell Labs and their colleagues have developed backscatter radios capable of gigabit speeds, for potential use in the emerging Internet of Things and other devices, a new study finds.

[...] [The] low frequencies that backscatter radios often employ and the strategies they use to encode data in reflected signals typically limit their data rates. For example, radio-frequency identification (RFID) tags, which often employ backscatter radios at sub-gigahertz frequencies, transmit data at only kilobits per second rates. At the 2.4 gigahertz frequency often used by WiFi and Bluetooth, backscatter is generally limited to hundreds of megabits per second.

Now scientists have developed a backscatter radio operating at millimeter-wave frequencies of 24 to 28 gigahertz, the kind used in upcoming 5G cell phones. The new device is capable of data rates of 2 gigabits per second over distances of 0.5 meters, consuming just 0.17 picojoules per bit. This means it requires thousands of times less power than standard radios—whereas commonly used millimeter-wave radio components consume 600 to 700 milliwatts of power, the new device uses roughly 0.5 milliwatts.

The new device consists of an antenna array and a single high-frequency transistor. The transistor can apply a voltage or not to make the antenna respectively either receive or reflect incoming signals.

A printed millimetre-wave modulator and antenna array for backscatter communications at gigabit data rates [nature.com] (open, DOI: 10.1038/s41928-021-00588-8) (DX [doi.org])

Original Submission