Researchers at the University of Washington have developed a technique they call “backscatter communication,” which backscatters or reflects existing signals like Bluetooth in the air, converting wireless transmissions from one technology to another; A team from the Department of Electrical Engineering and Computer Science at the University of Washington also demonstrated for the first time how Bluetooth transmission can be used to create Wi-Fi and ZigBee-compatible signals.
That said, the technology could bring power-constrained devices such as medical implants the ability to “talk” to other devices via standard Wi-Fi communications. Imagine tiny devices like smart contact lenses, brain implants, or credit cards, says Vikram Iyer, a UW doctoral student in electrical engineering and co-author of the paper: “They can’t use Bluetooth or Wi-Fi chips because would consume too much power in generating their own radio signals.”
“Inter-scattering communication” does not need to generate its own radio signal, and those inter-scattering devices can “recycle” the wireless signal transmitted by neighboring devices such as smart watches; Iyer explained: “We let things like smart watches, smart phones, etc. Devices do the power-hungry work of generating radio signals, and then low-power contact lenses, implants, or credit cards, etc., can reflect that signal in a way that encodes their own data.”
Iyer added that this inter-scattering component transmission is not a normal radio, but a switch linked to the antenna: “Turning this switch on and off allows us to change the way the antenna reflects energy; just by switching the switch At the right rate, our inter-scattering component can reflect the Bluetooth signal generated by a device like a smart watch, making it look like a Wi-Fi packet that a cell phone would receive.”
20160823-WIFI-1 “Inter-scattering” communication can generate low-power Wi-Fi transmission using everyday mobile devices; for example, the Bluetooth signal from a smart watch (left) in the picture can be transmitted by a brain implant device (right) Wi-Fi transfers data to smartphone (Source: Mark Stone, University of Washington)
For example, the team demonstrated the use of a smart watch to transmit a Bluetooth signal to a smart contact lens equipped with an antenna. In order to create a “whiteboard” that can write new messages, the University of Washington team developed a method to turn Bluetooth transmission into a smart contact lens that can be further read. A “single tone” signal for manipulation and conversion. By backscattering this single-frequency signal, the contact lens can encode data, such as collected health information, into standard Wi-Fi packets that can be read by a smartphone, tablet or laptop.
Maintaining battery life is critical for implantable medical devices; “If you have a radio in your implant that drains the battery very quickly, you may have to have surgery to change the battery,” says Lyer. “It’s like being invisible. Something as small as glasses might not even have enough power to power a typical Wi-Fi or Bluetooth chip with a tiny battery.” He pointed out that inter-scattering enables those implanted devices to be Wi-Fi capable, and the power required is those 1/10,000th of an ordinary Wi-Fi chip.
Many implanted devices have so far been unable to transmit messages because of their size and the ability to use Wi-Fi to transmit data to a smartphone or other mobile device because of their size and being contained within the human body; The ability of devices to communicate: “It could change the way we manage chronic diseases; for example, contact lenses could be used to monitor blood sugar levels in diabetics through tears and send notifications to mobile phones when blood sugar levels drop.”
When asked why the team chose to reflect the Bluetooth signal, Iyer replied: “Because Bluetooth is widely used in mobile devices, its frequency shift keying communication protocol makes it easy to convert using our technology into Wi-Fi;” he added: “We thought it would be cool to turn Bluetooth into Wi-Fi because of the high data rates. We also confirmed that the same technology could be used to turn Bluetooth into ZigBee, or even another Different Bluetooth packets.”
In developing this communication technology, the UW team also encountered several challenges; including the process of backscattering, which creates unwanted mirror copies of the signal, thus consuming more bandwidth, and the ability to interact with mirror-copy Wi-Fi channel networks interference between. But the team developed a technique called “single sideband backscatter” to avoid those unwanted by-products.
“That means we can only use the same bandwidth as a Wi-Fi network and still allow other Wi-Fi networks to function without interference,” said Bryce Kellogg, a UW electrical engineering doctoral student and co-author on the paper. The research team Three proof-of-concept examples were established for previously unfeasible applications, including smart contact lenses that communicate directly with smartphones, smart watches, and implantable neural recording devices.