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takyon [soylentnews.org] writes:

Computer scientists and electrical engineers at the University of Washington have created a device that can transmit Wi-Fi packets "passively" by reflection and absorption [futurity.org]. The system uses 0.01% of the power required by conventional Wi-Fi, transmits at bit rates up to 11 Mbps, and can communicate with existing devices at ranges up to 100 feet:

Wi-Fi is everywhere—invisibly connecting laptops to printers, allowing smartphones to make calls or stream movies without cell service, and letting online gamers battle it out. That's the upside. But there's a downside, too: Using Wi-Fi consumes a significant amount of energy, draining the batteries of all those connected devices.

Now, computer scientists and electrical engineers have demonstrated that it's possible to generate Wi-Fi transmissions using 10,000 times less power than conventional methods. The new Passive Wi-Fi [washington.edu] system also consumes 1,000 times less power than existing energy-efficient wireless communication platforms, such as Bluetooth Low Energy and Zigbee. "We wanted to see if we could achieve Wi-Fi transmissions using almost no power at all," says coauthor Shyam Gollakota, assistant professor of computer science and engineering at the University of Washington. "That's basically what Passive Wi-Fi delivers. We can get Wi-Fi for 10,000 times less power than the best thing that's out there."

Passive Wi-Fi can for the first time transmit Wi-Fi signals at bit rates of up to 11 megabits per second that can be decoded on any of the billions of devices with Wi-Fi connectivity. These speeds are lower than the maximum Wi-Fi speeds but 11 times higher than Bluetooth. [Note: this appears to refer to the 1 Mbps "basic rate" of Bluetooth [wikipedia.org].]

[...] The Passive Wi-Fi architecture assigns the analog, power-intensive functions—like producing a signal at a specific frequency—to a single device in the network that is plugged into the wall. An array of sensors produces Wi-Fi packets of information using very little power by simply reflecting and absorbing that signal using a digital switch. In real-world conditions, researchers found the passive Wi-Fi sensors and a smartphone can communicate even at distances of 100 feet between them.

[...] The researchers will present a paper [washington.edu] describing their results in March at the 13th USENIX Symposium on Networked Systems Design and Implementation. The National Science Foundation, the University of Washington, and Qualcomm funded the work.

University of Washington [washington.edu].

Original Submission