A team at the University of Washington (UW) have developed a concept that they call ‘passive WiFi’, which is up to 10,000 times more efficient than today’s wireless standards. It also consumes 1,000 times less power than existing efficient platforms, such as Bluetooth 4.0 and Zigbee.
Bit rates in the system are up to 11Mbps, consuming between 15µW and 60µW of power. Signals can be decoded on ‘any of the billions of devices with Wi-Fi connectivity’. These speeds are lower than conventional WiFi, but faster than Bluetooth. As well as smart devices, the system could be used with IoT products.
The digital and analogue operations involved in radio transmission were ‘effectively decoupled’ to achieve low-power WiFi transmissions. The team writes that the digital side of these operations has become very efficient over the last 20 years, but the analogue components still consume a lot of power.
Analogue functions (such as producing a signal at a specific frequency) are assigned to a single device in the network, which is plugged into the wall. An array of passive sensors produces packets of WiFi information, using little power, by absorbing and reflecting the signal with a digital switch. Distances of 10m – 30m were achieved in real-world conditions on the UW campus, in line-of-sight and through-the-wall scenarios.
“All [of] the networking, heavy-lifting and power-consuming pieces are done by the one plugged-in device,” said Vamsi Talla, a UW student and co-author of a paper on the technology (http://tinyurl.com/huwnrg4). “The passive devices are only reflecting to generate the Wi-Fi packets, which is a really energy-efficient way to communicate.”
Because the sensors are creating WiFi packets, they can communicate with any WiFi-enabled device. However, we understand that new chips will be required to make use of the system, much like WiDi.
A video of the system in use can be viewed below, or at http://tinyurl.com/z7kpwsb.
