The Secret of LiFi

High Speed Communications with Visible Light

LiFi is the latest technology for high-speed data communications inside of offices, homes and warehouses. Dr. Harold Haas of The Edinburgh University used the term “LiFi” in a  2011 Ted Talk (see end of article) to describe a “Light Fidelity” communication system using LED light bulbs.

Visible Light Communications (VLC) goes back to the 1880’s and was more recently tried with fluorescent lights, but was not widely adapted (primarily due to the very low data rates).

LiFi works with optical pulses in the LEDs to deliver high-speed bi-directional data communications between LiFi enabled devices. By slightly decreasing the electricity to the LED, a LiFi transmitter can broadcast a data bit. The frequency of light pulses is outside the range our receptors and optical nerves can process, so the data signals are imperceptible to the human eye. This is similar to a 50Hz or 60Hz AC electrical supply powering an incandescent bulb in that we don’t see any flicker.

Optical receptors in the LiFi device translate the variations in light intensity to a binary data stream.

For a more in depth treatment of LiFi and Visible Light Communications (VLC) technology, please take a look at this text available on Amazon: Visible Light Communication by Shlomi Arnon (Editor)

Under ideal conditions, data rates of 224 Gigabits per second have been achieved. However, when accounting for real world conditions and configurations with multiple transmitters in the same space, speeds are more typically in the 70 Megabits per second range.

All we need to do is fit a small microchip to every potential illumination device and this would then combine two basic functionalities: illumination and wireless data transmission. In the future we will not only have 14 billion light bulbs, we may have 14 billion LiFi’s deployed worldwide for a cleaner, greener, and even brighter future. – Harold Haas, PureLiFi Founder

A benefit, as well as detraction, of communications with light is that light beams do not pass through walls or solid objects, unlike radio waves (e.g., WiFi). The benefit is in providing a secure, localized communications network. But everything has to be within a line-of-sight of a LiFi enabled device to work.

Another issue concerns reflected light pulses. The technology for dealing with WiFi, Cellular and other RF reflections is well understood. Dealing with this interference for visible light based communications is still evolving.

As with all new technology, there is not yet an established product base of devices to work with. It is relatively simple to introduce a next generation WiFi Gigabit router (e.g, Starry ) since it will drop in and work with current WiFi enabled devices. With LiFi, an early adopter would need to purchase / install a network of LiFi enabled LED lightbulbs, add LiFi adapters to all existing devices and understand new methods for configuring and managing the network.

Similarly, there are only a few companies which are developing LiFi products. It took nearly 4 years from the time Professor Haas gave his Ted Talk until he was able to develop a commercial product through his Scotland based startup, PureLiFi. The main startup company in US working on this technology is VLNComm (funded by US Department of Energy and National Science Foundation grants).

LiFi, and other VLC technologies, and applications are being explored by Qualcomm, GE, Panasonic, Philips, Samsung, and OSRAM.

Please read the second part of this article which discusses the Interesting Uses for LiFi Visible Light Communications.

Below is the Professor Haas’ Ted Talk on the topic.

 

 

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