In a recent breakthrough at the University of Washington, a group of researchers from the electrical engineering dept. have invented a new type of WIFI technology called Passive WiFi. PASSIVE WIFI is 10000 times more energy efficient than traditional WIFI equipment. It’s like any other home router but consumes considerably less power in comparison to them.
Passive WiFi is an innovation that can revolutionize the wireless communication industry. Wi-Fi has traditionally been considered a power-consuming communication system and has not been widely adopted in the sensor network and IoT space. Battery drain due to WiFi had been a major problem for researchers as there is a demand for more energy efficient technologies.
Passive Wi-Fi can generate 802.11b transmissions using backscatter communication, while consuming power that is 3 - 4 orders of magnitude lower power than existing Wi-Fi chipsets. Passive Wi-Fi transmissions can be decoded on any Wi-Fi device including routers, mobile phones and tablets. The researchers presented a network stack design that enables passive Wi-Fi transmitters to coexist with other devices in the ISM band, without incurring the power consumption of carrier sense and medium access control operations. They also built a prototype hardware and implement all four 802.11b bit rates on an FPGA platform.
Their design has two main actors, a plugged-in device and passive Wi-Fi devices. The former contains power consuming RF components including frequency synthesizer and power amplifier and emits a single tone RF carrier. It also performs carrier sense on behalf of the passive WiFi device and helps coordinate medium access control across multiple passive Wi-Fi devices. The passive WiFi device reflects/backscatters the tone emitted by the plugged-in device to synthesize 802.11b transmissions that can be decoded on any device that has a Wi-Fi chipset. As the passive WiFi device is just reflecting the tone, so almost no power needed.
To learn more about this technology you can download the original White Paper on Passive WiFi.
