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Visible light communication (often abbreviated as VLC) is a method of optical wireless communication that relies on LED lights and the visible light spectrum. VLC uses light emitted by LEDs to create networked, mobile, and high-speed communication similar to Wi-Fi (because of this, VLC is oftentimes referred to as Li-Fi, short for "Light Fidelity"). VLC involves switching LED lights on and off within nanoseconds at a tremendously high frequency. It can be used as a complement or as a standalone solution for radio-frequency (RF) or cellular network communication.
VLC works by utilizing the spectrum of light that is visible to the human eye (aptly titled the visible light spectrum) to transmit data wirelessly from one point to another. In VLC, data is transmitted by rapidly adjusting the intensity of light given off from a light source, most commonly LEDs. The signal is then received by a photodiode device, which can transform the data into something easily readable and consumable by the end user.
A diagram illustrating the visible light spectrum as compared to the rest of the electromagnetic spectrum. Source: researchgate.net
Proponents of VLC view it as having many advantages over traditional radio-frequency communication. VLC's biggest advantage is the visible light spectrum's massive size, which is 10,000 times larger than the entire radio spectrum. Additionally, overuse of the radio spectrum has made it congested. VLC also has the ability to transmit data faster than radio frequency, as the speed of light travels at 186,000 miles per second, which trounces the speed that radio waves travel 344 meters per second. This speed makes data transmitted over VLC virtually instantaneous.
There are several characteristics that are unique to VLC compared to other forms of optical wireless communication. The first is signal confinement. Because light is unable to travel through opaque walls, VLC is ideal when the signal is confined to a single room, and adds to security. Second, VLC is not dependent on line-of-sight, meaning that even with significant obstructions, VLC is still functional. Finally, VLC is seen as being ideal for use in hazardous environments where radio-frequency waves cannot be used, such as in hospitals, airplanes, or mines.
VLC was introduced to the world by Harald Hass at TEDGlobal 2011. Hass had been researching VLC for a decade prior, earning a PhD in wireless communications from the University of Edinburgh in 2001. At TEDGlobal, Hass showcased how overhead lighting could be used in high-speed networking during his talk, "Wireless Data from Every Light Bulb," where he also coined the term "Li-Fi" to refer to VLC. After the talk, Hass went on to found pureVLC Ltd., later renamed PureLiFi, with other University of Edinburgh researchers.
Harald Hass introducing VLC to the world during his 2011 TEDGlobal talk, "Wireless Data from Every Light Bulb."
VLC is seen as having high potential in many areas of society, including in the academics, automotive, everyday electronics, aviation, and aeronautics industries. As a result, many electronics companies have or are developing VLC programs in the hopes that it will someday be easily implemented. As of 2021, the biggest VLC companies are Signify, PureLiFi, Oledcomm, and VLNComm. Other VLC companies include the following:
