Passive Wi-Fi is a refinement of

Wi-Fi Wi-Fi () is a family of wireless network protocols, based on the IEEE 802.11 family of standards, which are commonly used for local area networking of devices and Internet access, allowing nearby digital devices to exchange data by radio wave ...

technology that uses passive reflection to reduce energy consumption.

Wi-Fi energy use

Wi-Fi use can account for up to 60 percent of a

smartphone A smartphone is a portable computer device that combines mobile telephone and computing functions into one unit. They are distinguished from feature phones by their stronger hardware capabilities and extensive mobile operating systems, whic ...

's energy consumption. When not connected to a network, Wi-Fi consumes energy because the device constantly searches for a signal.

Backscattering

The technique communicates via backscattering, reflecting incoming radio waves sent from a separate device. The technique is similar to contactless

RFID chip Radio-frequency identification (RFID) uses electromagnetic fields to automatically identify and track tags attached to objects. An RFID system consists of a tiny radio transponder, a radio receiver and transmitter. When triggered by an electrom ...

cards although unlike such cards, the new technique does not require a special device to read the signal. The project effectively decoupled the analog and the digital radio signals. Power-intensive functions – like producing a signal at a specific frequency are assigned to a single device in the network that is plugged into the grid. Smartphones modify and reflect this signal to communicate to the router. Prototype passive devices transferred data as far as 100 feet through walls at 11 megabits per second. The system used tens of microwatts of power, 10⁻⁴ less energy than conventional Wi-fi devices, and one thousandth the energy of Bluetooth LE and

Zigbee Zigbee is an IEEE 802.15.4-based specification for a suite of high-level communication protocols used to create personal area networks with small, low-power digital radios, such as for home automation, medical device data collection, and othe ...

communications standards.

Applications

Applications include smart home devices such as

smoke detectors A smoke detector is a device that senses smoke, typically as an indicator of fire. Smoke detectors are usually housed in plastic enclosures, typically shaped like a disk about in diameter and thick, but shape and size vary. Smoke can be detecte ...

temperature sensor Mechanical temperature sensors * Thermometer * Therm Electrical temperature sensors * Thermistor- Thermistors are thermally sensitive resistors whose prime function is to exhibit a large, predictable and precise change in electrical resistance whe ...

s and

security cameras Closed-circuit television (CCTV), also known as video surveillance, is the use of video cameras to transmit a signal to a specific place, on a limited set of monitors. It differs from broadcast television in that the signal is not openly tr ...

that will no longer require a power source.

References

{{reflist, 30em Wi-Fi Internet of things