Let there be light ... based wireless networks: LiFi spec OK'd as Wi-Fi complement

Talk about a bright idea

IEEE 802.11bb, an amendment to the Wi-Fi specification that supports wireless networking using visible and infrared light instead of the radio spectrum, was approved last month by the electrical engineering body.

The IEEE 802.11bb Light Communication Global standard, referred to as LiFi, describes the necessary changes to physical layers (PHY) and the medium access control layer (MAC) to allow 802.11 wireless networking via light source modulation that, mercifully, people can't see.

The LiFi spec calls for bidirectional transmission in the 800nm to 1,000nm band of the electromagnetic spectrum, with a minimum throughput of 10 Mb/s and a maximum of 9.6 Gb/s at the MAC data service access point.

As a point of comparison, Wi-Fi operates over wavelengths of 120mm (2.4 GHz) and 60mm (5 GHz), with transmission speeds that depend on the version. Wi-Fi 6 (like LiFi) tops out at 9.6 Gb/s.

On Thursday this week, pureLiFi, based in Scotland, UK, and Fraunhofer HHI, based in Germany, celebrated the LiFi spec's approval, saying the new standard sets the stage for LiFi systems to interoperate with Wi-Fi networks.

"The IEEE 802.11bb standard is a critical step to enable interoperability between multiple vendors," said Volker Jungnickel from Fraunhofer HHI, who served as technical editor of the task group, in a statement. "It allows for the first time LiFi solutions inside the Wi-Fi ecosystem."

According to Jungnickel, interoperability with Wi-Fi is necessary to support the development of novel LiFi applications.

Initially, LiFi is being positioned as a complement to Wi-Fi systems, an option that provides a way to add extra bandwidth without increasing network congestion or interference. The shiny new technology also has potential as a way to thin cable thickets.

"LiFi can replace cables by short-range optical wireless links and connect numerous sensors and actuators to the Internet," said Jungnickel. "We believe that this will create a future mass market."

Network backhaul is preferably power-over-Ethernet (POE) for new installations or power line communications (PLC) for retrofits.

With a LiFi attachment such as the pureLiFi's Light Antenna ONE plugged into a laptop, the computer should be able to send and receive data at a rate of more than 1 Gb/s.

Since LiFi access points have a limited field of view, it's possible to set up environments where pools of LED light provide network access only to those within them.

Some of pureLiFi's systems work without visible light, via infrared transmission. Other components require some level of illumination for transmission. These work at low light levels – about 10 percent of maximum. That translates to 60 lux, where 400 lux represents the UK minimum standard for reading, according to the company.

WTF is... Li-Fi?


One of the rationales for LiFi is security. According to pureLiFi, the technology is "inherently secure" – walls serve as firewalls since light does not pass through them – and is already being used at military facilities.

"Light's line-of-sight propagation enhances security by preventing wall penetration, reducing jamming and eavesdropping risks, and enabling centimeter-precision indoor navigation," said Dominic Schulz, lead of LiFi development at Fraunhofer HHI, in a statement.

pureLiFi suggests that being able to see into a room with active LiFi via a telescopic lens would not provide a data interception opportunity. The biz claims such lenses have a narrow field of view and could only see an uplink or downlink light source, not both.

"Even with a telescope, any signal detected would typically be too low in energy for successful decoding/demodulation," the company insists, as if daring security researchers to prove otherwise. ®

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