Let There Be Light: Here Comes Li-Fi

By Randy Field

There have been many projections as to the number of IoT devices that will be deployed by 2020 – and, coincidentally, there are doubters of those projections. A new ally for achieving the 2020 promise emerged in 2011 and is reaching the commercial market soon: Light Fidelity (Li-Fi) networks. Li-Fi is in a subset of “visible light communication” (VLC) called “optical wireless communication” (OWC).

Similar to Wi-Fi, Li-Fi is a bidirectional, high speed wireless network that has the promise of operating at up to 1000 times faster. Light is used as a carrier signal instead of Wi-Fi’s traditional radio frequency (RF). In recent testing, switched LED lamps reached data speeds of up to 224 gigabytes per second – 100 times faster than some Wi-Fi networks. At this speed, 15 -20 movies can be downloaded in one second. A typical 120V light bulb is switched at 60 cycles per second or 60 hertz (Hz). Li-Fi equipped LED lamps can be switched between 400 and 800 terahertz (THz). While both create visible light, these lamps can effectively operate in darkness.

Given that visible light does not penetrate walls, it is very secure. Devices must be in the lit area but do not require line of sight. It can reflect off walls or other objects. Using light has other benefits over RF waves, too. These benefits include: less chance of interference from other RF signals, improved communication speeds in dense urban environments, outdoor high-speed Internet networks using street lights, retailer in-building advertising, hospital communications in areas where RF usage is prohibited, passenger Internet access on airplanes to eliminate potential RF interference with airplane instruments – and, underwater communications.

Li-Fi is rapidly moving from the lab to commercial use. Some solutions are launching at communication speeds comparable to Wi-Fi. Arrays of red, green and blue (RGB) LEDs can create a bidirectional network operating on different frequencies. Apple iPhones have backlit LED screens. Industry buzz indicates that Apple is including Li-Fi code in an iOS9 update for use in the iPhone 7. These developments might be related to their Connected Home initiative.

Li-Fi will not replace WiFi in the near future. Although, history is repeating itself. To get additional frequencies of operation for wired networks, copper wire was replaced by fiber optics. Wi-Fi has limited, fixed frequency communications: 2.4GHz, 4.9 GHz and 5GHz. Li-Fi has 10,000 times more frequency options. Wi-Fi networks slow down under heavy demand, but Li-Fi is not affected by density. Over-the-air (OTA) software updates to many devices in one area is possible without losing download speed. Wi-Fi can penetrate walls and has a larger coverage area, while Li-Fi is currently limited to approximately 30 feet in a visible space. Traditional Wi-Fi networks need more hardware: a router and end-points with embedded network information cards (NICs), where as Li-Fi networks use a lamp driver (ballast), photo detectors and a lamp. For bidirectional Li-Fi communication, a receiver needs to be added to the Li-Fi network.

Two billion light bulbs are sold each year. All that is needed to change an illumination device such as a LED bulb into a Li-Fi device is an embedded, dual-purpose illumination and wireless data communication chip. When end points are included, the total number of new Li-Fi devices increases exponentially. The Li-Fi market is projected to grow quickly to $6 Billion by 2018. Going forward, the Internet of Things has a new baby. Every new IoT network delivers alternate solutions for the emerging use cases. The bold 2020 projections might be coming into focus.