Why LiFi? by Roger Pink

The Coming Data Crunch

Everywhere you look nowadays, the world is becoming more mobile. Smart phones, phablets, tablets and laptops increasingly demand wireless bandwidth for applications, music, movies and other media. With the fast adoption of these devices in developing nations and the insatiable thirst for more bandwidth in mature markets, it is estimated that by 2017 more than 11 exabytes of data traffic will have to be transferred through mobile networks every month [1]. Considering that this estimate doesn't include the data traffic that will be generated by technologies that haven't become mainstream yet, but are likely to be increasingly adopted (streaming TVs, smart watches, smart appliances, etc.), it's not hard to anticipate a future wireless data capacity shortage.

An impending capacity calamity isn't the only issue facing today's wireless communications. There are also limits to its availability in hospitals, on aircraft, and wherever else radio frequency (RF) interference can cause problems. Wireless networks are also not very secure; RF can penetrate walls, which creates security risks. Wireless networks are also energy inefficient. There has been a movement toward microcells, picocells and femtocells that increase bandwidth in areas of high wireless data usage (train stations, airports, etc.) in a targeted way, but still, the amount of energy needed for wireless communications is growing very quickly and will ultimately be unsustainable.

LiFi to the Rescue!

Fortunately there is an emerging technology that is able to address the wireless data problems of capacity, availability, security and efficiency. The technology is called LiFi, short for "light fidelity," and it was on display at CES this year. A company called Oledcomm demonstrated a modified smartphone that used LiFi and was able to achieve wireless data rates of 1 Gbits/s.

LiFi devices are rare and the technology is still very much in the development stage. The concept of LiFi is simple enough. There already exists an extensive lighting infrastructure for illumination-from the light bulbs in your house, to the street lamps outside, to the personal lights you use to read on a plane or train. LiFi could take advantage of this existing infrastructure by modifying those illumination sources and turning them into LiFi transceivers. The idea is if you blink those light sources extremely fast, far faster than the human eye can detect, you could use that intensity modulation to transmit data.

For traditional sources of illumination, like incandescent lamps or fluorescent lamps, this wouldn't work. But LED light sources, quickly being adopted worldwide due to its energy efficiency and long life, can have their intensity modulated quickly and precisely enough to make LiFi a reality. Of course, the LED lamps commercially available today are not appropriate for LiFi. New lamps with embedded microchips and a photodetector (so it can receive data as well as transmit) will have to be created in order for what is being called visible light communication (VLC) to become reality.

LiFi and the Internet of Things

The development of visual light communication comes at an opportune time, as the internet of things is just starting to gain traction. The internet of things is a holistic term for the virtual representation of everyday objects, such as appliances, electronics, thermostats, vehicles and much more, on wireless networks. Connecting devices wirelessly to a network allows for remote operation, better tracking of usage and better inventory controls. A popular example of how this might be useful is receiving a notification from your refrigerator when you are out of milk, or being able to adjust your thermostat with your phone. This can only occur if your refrigerator or thermostat is connected to a network, and that's why LiFi is so well suited for the internet of things. LEDs and photodiodes are relatively cheap to manufacture and have a small form factor, so they are easily integrated into most household devices. Once integrated, the LED/photodiode is effectively a LiFi transceiver, communicating with the local LiFi hub.

Conclusions

If LiFi does become a reality, it certainly will solve some of the problems facing wireless data. For one thing, there is far more capacity available by using the visible light part of the spectrum rather than the radio wave part that is currently used by wireless networks. Already LiFi has demonstrated fast data rates with the potential for significant improvement. Since LiFi uses the visible spectrum, it won't interfere with electronic devices like WiFi would. This would mean no worries in hospitals and other WiFi-prohibited areas. Since walls are generally impenetrable to visible light security risks are reduced. Best of all, LEDs are efficient emitters, meaning that the integration of LiFi into micro, pico and femtocell networks will appreciably reduce the energy usage of wireless networks even as wireless data usage grows exponentially.

LiFi is many years away from becoming a reality. Standards are being developed and technologies improved. Still, the promise of LiFi combined with the incredible demand for more wireless bandwidth make this emerging technology a leading candidate for the future of wireless networks.

Resources

[1] Cisco Visual Networking Index, "Global Mobile Data Traffic Forecast Update, 2012-2017," White Paper, CISCO (Feb. 2013).]