Introduction to Li-Fi - Wireless Networking with Light

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Light Fidelity technology, more commonly called Li-Fi, supports local area network connections like Wi-Fi except using visible light instead of radio signals.

Data Through Illumination

Li-Fi was created as an alternative to radio frequency (RF) based network technologies. As wireless networking has exploded in popularity, it has become increasingly difficult to carry these massive amounts of data over the limited number of radio frequency bands available.

Harald Hass, a researcher at the University of Edinburgh (Scotland), has been labeled the Father of Li-Fi for his efforts in advancing this technology. His TED talk in 2011 brought the Li-Fi and the University’s D-Light project into the public spotlight for the first time, calling it “data through illumination.”

How Li-Fi and Visible Light Communication (VLC) Work

Li-Fi is a form of Visible Light Communication (VLC). Using lights as communication devices is not a new idea, dating back more than 100 years. With VLC, changes in the intensity of the lighting can be used to communicate encoded information. Early forms of VLC used traditional electric lamps but could not achieve very high data rates. The IEEE working group 802.15.7 continues to work on industry standards for VLC.

Li-Fi uses white light-emitting diodes (LEDs) rather than traditional fluorescent or incandescent bulbs. A Li-Fi network alters the intensity of the LEDs up and down at extremely high speeds (too fast for the human eye to perceive) to transmit data, a kind of hyper-speed morse code.

Similar to Wi-Fi, Li-Fi networks require special Li-Fi access points to organize traffic among devices. Client devices must be built with a Li-Fi wireless adapter, either a built-in chip or a dongle.

Advantages of Li-Fi Technology

Li-Fi networks avoid radio frequency interference, an increasingly important consideration in homes as the popularity of Internet of Things (IoT) and other wireless gadgets continues to increase.

Additionally, the amount of wireless spectrum (range of available signal frequencies) with visible light far exceeds that of radio spectrum like that used for Wi-Fi - a commonly-cited statistic claims 10,000 times greater. This means Li-Fi networks should theoretically have a huge advantage over Wi-Fi in ability to scale up to support networks with much more traffic.

Li-Fi networks are built to take advantage of already-installed lighting in homes and other buildings, making them cheap to install. They function much like infrared networks that use wavelengths of light invisible to the human eye, yet Li-Fi doesn’t require separate light transmitters.

Because the transmissions are restricted to areas where light can penetrate, Li-Fi offers a natural security advantage over Wi-Fi where signals easily (and often by design) seep through walls and floors.

Those who question the health effects of prolonged Wi-Fi exposure on humans will find Li-Fi a lower-risk option.

How Fast is Li-Fi?

Lab tests indicate Li-Fi can operate at very high theoretical speeds; one experiment measured a data transfer rate of 224 Gbps (gigabits, not megabits). Even when the practicalities of network protocol overhead (such as for encryption) are taken into account, Li-Fi is very, very fast.

Issues with Li-Fi

Li-Fi cannot work well outdoors due to interference from sunlight. Li-Fi connections also cannot penetrate through walls and objects that block light.

Wi-Fi already enjoys a huge installed base of home and business networks around the world. To expand on what Wi-Fi offers requires giving consumers a compelling reason to upgrade and at a low cost. The extra circuitry which must be added to LEDs to enable them for Li-Fi communication must be adopted by major bulb manufacturers.

While Li-FI has enjoyed great results from lab trials, it may still be years away from becoming widely available to consumers.