Using Visible Light for Broadband Internet
WiFi has already become a household term in the industrialized world and in many developing countries. WiFi is a wireless data communications technology that uses radio frequencies to transfer data, and radio is a part of the electromagnetic spectrum – the range of possible frequencies of electromagnetic waves (also called photons as they are part of the heat / light package provided by the Sun and other sources of light / heat in the Universe). Different ranges of frequencies within this spectrum constitute different types of electromagnetic waves. In addition to radio, there are microwaves, infrared, ultraviolet, X-rays, gamma rays, and the visible light we are so familiar with. When internet service providers give internet connection, they are essentially allocating a specific bandwidth to a customer from the available bandwidth of the entire radio frequency spectrum. According to the U.S. Federal Communications Commission (FCC), based on the growing needs for WiFi, within a few years (from 2014), there won’t be enough of the radio frequency (RF) spectrum to satisfy all consumers, causing network bottlenecks and a loss of efficiency in data transfer. Enter LiFi.
LiFi (short for Light Fidelity) is a new technology that uses visible light to transfer data instead of radio waves. As illustrated in the image below, visible light has a frequency spectrum that is around 10,000 times larger than the RF spectrum.
Born out of a potential RF spectrum crisis, LiFi is capable of giving users data transfer rates many times faster than WiFi. Best of all, the entire optical wireless communications technology setup can work with existing lighting structures, like common household LED lightbulbs. A LiFi-enabled device need only be in the line of sight of an LED router / lightbulb to have internet access or in a room lighted by LiFi routers only so that light that is reflected off of the walls is received by the device. [i] [ii] [iii]
How LiFi Works
At their core, all electronics are simply a combination of integrated circuits that are themselves comprised of a series of switches that can be turned on or off. In the digital world, like in our computers or smartphones, all data is made possible by a combination of on-off switches called transistors within the integrated circuit. ‘0’ is typically used to represent a switch that is off and a ‘1’ a switch that is on. Certain combinations may represent letters of the alphabet and number values, and as the combinations become increasingly complex, so does the data they represent, making it possible for computers and other electronic devices to store and transfer the music we listen to, the videos we watch, the documents we read, and the games we play. All computer input / output (I/O) devices (like monitors, keyboards, mice, printers, gamepads, modems, WiFi networking cards / routers, etc.) communicate with the CPU of the computer (directly or indirectly) by converting the data that exists as a combination of on-off electric switches to (and from) whatever type of data storage / transfer method the particular I/O device uses. Data transfer through a LiFi networking device, like an LED lightbulb, is achieved through a combination of flickers of the lightbulb over a very short duration, where the flickers are the on-off switching that represents data. These flickers are so fast that they can’t be detected by the human eye, so as far as we’re concerned, the lightbulb has been on the entire time!
LED devices are made from semiconductor material, just like the transistors of integrated circuits in a computer or other modern electronic device. Semiconductors such as silicon are used as on-off switches because their chemical properties facilitate fluctuations in electric voltage that serve as the on-off switches. Just as in other electronic devices, LED lightbulbs need not be turned off all the way to indicate a binary ‘0’ but instead, a specific voltage can be defined as ‘0’ while another specific voltage can be defined as ‘1’, resulting in a rapid dimming and brightening that represents data to a device that is LiFi-enabled. To enable a device with LiFi, it must contain a modem / router that includes a photodetector device so that it can convert the light flickering into electric voltage pulses which represent data within the computer or smartphone. As shown by illustration below, the streaming video travels from the internet through fiber optic cables to LED lamps at the home or office that work to convert this data stream into light flickering and the computer’s receiver dongle containing a photodetector device works to convert this flickering back into data that the computer understands. This is very similar to the way a WiFi networking card in a computer sends / receives data, except it uses radio waves instead of visible light as its medium for data transfer.
LiFi vs WiFi
LiFi and WiFi are both wireless technologies that transfer data through electromagnetic waves but because of the distinctive characteristics of light and radio waves, LiFi and WiFi have many key differences.
Speed, Data Density and Interference
One of the key advantages of LiFi over WiFi is its speed. In controlled lab experiments, LiFi can transmit data up to 224 gigabits per second or 28 GB / s while WiFi can reach up to only 867 megabits per second or around 108 MB / s. One of the main reasons for this difference is data density – since LiFi works fastest within the line of sight of the LED lamp transmitting data, the signal is guided in one direction rather than spewing out radially like with WiFi connections. And even if the device receiving data is not directly under the LED lamp and the light bounces off of the walls, LiFi still has been able to achieve speeds of 70 gigabits per second or 8.75 GB / s. Another reason for LiFi’s speed advantage is the lack of interference – since visible light doesn’t penetrate walls or interact with circuitry, there is less to interfere with its travel and therefore less to restrict its speed as it will repeatedly bounce around within the room / office until it reaches a modem containing a photodetector device that can read it.
Security and Range
Since light doesn’t penetrate walls or other such structures, it’s very difficult for anyone outside of the working area to hack the connection or eavesdrop on confidential data, reducing the need for additional security per user in the company. While LiFi is more secure, WiFi has better range. LiFi significantly limits the working area but improvements in technology like a LiFi room connector, an optical fiber cable connection between the two rooms so that data in the visible light in one room can be shared with the other, or simply placing multiple LiFi LED lights in the same room can overcome this limitation, as suggested by the image below, taken from a Boston University illustration of how LiFi could work in an office setting.
One of the inherent disadvantages of LiFi is that it requires the LED lamp to be on for as long as internet connection is required whereas WiFi has no such drawback. While there is usually illumination where people wish to use the internet, if a user does not wish to be bombarded with visible light just to be able to use the internet, then they are out of luck with a LiFi connection. As the technology advances, though, LiFi LED lightbulbs will work with an increasingly dimmer luminosity.
While LiFi can be very effective for indoor settings, another reason it won’t work well for outdoor use is interference with sunlight. LiFi doesn’t suffer from interference problems with many substances but it does with sunlight because both are photons and must interfere. Established mobile wireless transfer methods will remain the standard for outdoor connections.
And the biggest disadvantage of LiFi is that it is rarely bidirectional. Technically, it can be, but since LED lightbulbs are designed to be providers of light and not receivers, sending a connection back through the LED lamp would cost additional setup. However, it is certainly possible and with time, this limitation will be overcome. For now, though, LiFi seems to be excellent at delivering data to the end user for uses like audio / video streaming but not when the end user needs to send data for even simple bidirectional use, like email. These are the reasons, initially, LiFi will serve only as a complement to WiFi.
Still, LiFi has many real-world applications. Existing private and public lighting can be used as LiFi hotspots for internet connectivity. Since computers / smartphones already emit light, they can be used to connect to other similar devices, serving as an incredibly fast and secure substitute for Bluetooth. LiFi provides a safe alternative to electromagnetic interference from radio frequency communications in hazardous environments such as mines and petrochemical plants or with medical instruments like MRI scanners. LiFi can be used on airplanes to reduce the infrastructure and cabling required to provide WiFi because LED lighting already exists for passengers, reducing aircraft weight and cost. For short-range underwater communications, since radio waves are absorbed by water and acoustic waves disturb marine life, LiFi is a good solution; this can definitely have scientific applications.
Ecological Impact and Infrastructure
Typical uses of radio waves include WiFi, television, cellular service, AM / FM radio, and other such services; radio towers and masts must generate the radio waves that enable the services. Radio towers are known for their inefficiency – most of their power is used for cooling while only 5% is used for actual data transmission – whereas LED lamps serve as illuminators plus internet providers with the installation of only a microchip to enable them for LiFi and a photodetector technology attached to the computer / smartphone receiving the LiFi internet connection. While some investment is required to make household / office lighting structures LiFi service drivers as opposed to the established radio wave-based technologies like WiFi, this investment is very limited and inexpensive. LED lighting is efficient for illumination and a growing technology worldwide even before the introduction of LiFi.
Bandwidth, Licensing, and Standards
According to the Cisco Global Mobile Data Traffic Forecast, the monthly global mobile data traffic by 2020 will be 30.6 exabytes (EB) or 30.6 million terabytes (TB), which is by itself usage that the existing wireless communications infrastructure cannot cater to, and this doesn’t even take into account all other radio wave-based communications technologies. The visible light spectrum is 10,000 times greater than the radio spectrum and operates on an entirely different range of frequencies than WiFi’s radio waves. Also, LiFi is currently not regulated by any government authority and therefore allows easy entry for internet service providers into the LiFi industry. However, it should be noted that the Institute of Electrical and Electronics Engineers (IEEE), the world’s largest and most established promoter of the advancement of technology, is currently developing a standard for Visible Light Communications (VLC) called IEEE 802.15.7. (The standards for WiFi that the global WiFi industry follows include 802.11a/b/g, 802.11n, and 802.11ac/ad/af/ah/ai/aj/aq/ax/ay).  [iv] [v] [vi] [vii] [viii] [ix] [x] [xi]
The Future of LiFi
The term ‘LiFi’ was coined at TEDGlobal (the annual worldwide technology conference) by Harald Hass, a German physicist and professor at the University of Edinburgh. Considered the father of LiFi, Hass and a group of researchers who were part of the renowned D-Light project which had undertaken pioneering research into visible light communications since 2008 formed the company pureLiFi, for which Professor Hass is now Chief Science Officer (CSO). The timeline below summarizes the key milestones of the company.
At the Mobile World Congress held in February 2014 in Barcelona, pureLiFi demonstrated the first LiFi system designed for commercial needs. Later the same year, a Russian company by the name of Stins Coman launched their local wireless network called BeamCaster that uses a LiFi router and receivers for each computer on the network. On 25 November 2015, pureLiFi announced a partnership with a French industrialized lighting company by the name of Lucibel to launch LiFi-enabled LED devices by quarter 3 of 2016. At around the same time, the CEO of Velmenni Deepak Solanki said that LiFi could become a common product for end consumers in three to four (3 – 4) years. His company is also installing LiFi for small company office spaces. And LiFi technology is already growing to work with solar charging LED mobile screen technology to produce mobile devices that not only charge the phone by sunlight, but also are capable of streaming data from the internet using LiFi LED lightbulbs. SunPartner Technologies and 3M call their solar-charging screen layer Wysips. SunPartner has partnered with a French technology company called Oledcomm to unveil Wysips Connect, their solar-charging LiFi-enabled mobile phone screen layer.  [xii] [xiii] [xiv] [xv] [xvi]
Born out of a need to develop technologies alternative to WiFi and other radio wave-based communications, LiFi offers many advantages and is already suitable for a hybrid data communications setup that uses the existing infrastructure and technologies and utilizes the cutting-edge capabilities of LiFi to get the best of both worlds. The LED industry has already been growing and with the advent of LiFi, both will feed off of each other to thrive. According to MarketsandMarkets, a full-service market research company that produces over 1200 reports per year more than 10 different industries, forecasts that the global visible light communication (VLC) / LiFi technology market will grow to more than a $6 billion industry by 2018. Even beyond this forecast, LiFi will continue to grow, and with time and constant advancement of LiFi and other related technologies, this industry may even become the dominant data communications technology of the world. [xvii]
If you have any questions about Li-Fi, go to www.betterlifi.com.
i Haas H. Optoelectronics & Communications: High-speed wireless networking using visible light. SPIE – the international society for optics and phonics. [accessed 2016 Feb 17]; SPIE Newsroom. http://www.spie.org/newsroom/technical-articles/4773-high–speed-wireless-networking-using-visible-light. doi:10.1117/2.1201304.004773.
ii Mercer C. 2016 Feb 11. What is Li-Fi? How does Li-Fi work? Wi-Fi vs Li-Fi vs Wi-Fi HaLow: Li-Fi for iPhone: The ultimate definition of Li-Fi. techWorld. [accessed 2016 Feb 17]; IDG UK. http://www.techworld.com/big-data/what-is-li-fi-everything-you-need-know-3632764/.
iii Armstrong, J. 2013 Dec 7. The Science Show: The internet on beams of LED light. ABC Radio National (Australian Broadcasting Corporation). [accessed 2016 Feb 17]. http://www.abc.net.au/radionational/programs/scienceshow/the-internet-on-beams-of-led-light/5134888.
iv Belle A, Falcitelli M, Petracca M, Pagano P. 2013 Nov 5-7. [Abstract] Development of IEEE802.15.7 based ITS services using low cost embedded systems. IEEE. [accessed 2016 Feb 17]; 6685583:419-425. http://ieeexplore.ieee.org/xpl/articleDetails.jsp?reload=true&arnumber=6685583. doi:10.1109/ITST.2013.6685583
v Taub B. 2015 Nov 24. New Li-Fi Internet Is 100 Times Faster Than Wi-Fi. IFLScience. [accessed 2016 Feb 17]. http://www.iflscience.com/technology/li-fi-internet-could-be-100-times-faster-wi-fi-0.
vi 2016 Feb 3. [Summary] Cisco Visual Networking Index: Global Mobile Data Traffic Forecast Update, 2015–2020 White Paper. Cisco. [accessed 2016 Feb 17]. http://www.cisco.com/c/en/us/solutions/collateral/service-provider/visual-networking-index-vni/mobile-white-paper-c11-520862.html.
vii 2015. Li-Fi Network. Li-Fi Consortium. [accessed 2016 Feb 17]. http://www.lificonsortium.org/tech6.html.
viii Sherman J. 2013 Oct 30. Light bulbs could replace your Wi-Fi router. Digital Trends. [accessed 2016 Feb 17]. http://www.digitaltrends.com/mobile/light-bulb-li-fi-wireless-internet/.
ix Paul I. 2015 Nov 30. Light-based ‘Li-Fi’ beams data 100 times faster than Wi-Fi. PCWorld. [accessed 2016 Feb 17]. http://www.pcworld.com/article/3009241/networking/light-based-li-fi-beams-data-100-times-faster-than-wi-fi.html.
x Thomson I. 2013 Oct 18. Forget Wi-Fi, boffins get 150Mbps Li-Fi connection from a lightbulb. The Register. [accessed 2016 Feb 17]. http://www.theregister.co.uk/2013/10/18/forget_wifi_chinese_boffins_get_150mbps_lifi_connection_from_a_lightbulb.
xi Gilbert D. 2015 Nov 25. What Is Li-Fi? Meet The Revolutionary Wireless Technology That Is 100 Times Faster Than Wi-Fi. International Business Times. [accessed 2016 Feb 17]. http://www.ibtimes.com/what-li-fi-meet-revolutionary-wireless-technology-100-times-faster-wi-fi-2199883
xii 2011. Harold Hass: Wireless data from every light bulb. TED Talk. [accessed 2016 Feb 17]. http://www.ted.com/talks/harald_haas_wireless_data_from_every_light_bulb.
xiii Freer N. 2014 Feb 19. pureLiFi to demonstrate first ever Li-Fi system at Mobile World Congress. Virtual-Strategy Magazine. [accessed 2016 Feb 17]. http://www.virtual-strategy.com/2014/02/19/purelifi-demonstrate-first-ever-li-fi-system-mobile-world-congress#axzz3sutgmdn1.
xiv Pototsky D. 2014 Jul 1. Li-Fi internet solution from Russian company attracting foreign clients. Russia & India Report. [accessed 2016 Feb 17]. http://in.rbth.com/economics/2014/07/01/li-fi_internet_solution_from_russian_company_attracting_foreign_cli_36347.
xv Camp JV. 2014 Jan 19. Your next phone may charge and receive data through this incredible screen. Digital Trends. [accessed 2016 Feb 17]. http://www.digitaltrends.com/mobile/wysips-solar-charging-screen-li-fi-impressions/.
xvi Piltch A. 2014 Jan 8. Bright Idea: Smartphone Sensor Receives Data Via Light. LAPTOP. [accessed 2016 Feb 17]. http://www.laptopmag.com/articles/wysips-connect-lifi-downloads-data].
xvii Rohan. 2013 Jan 10. Global Visible Light Communication (VLC)/Li-Fi Technology Market worth $6,138.02 Million by 2018. PR Newswire. [accessed 2016 Feb 17]. http://www.prnewswire.com/news-releases/global-visible-light-communication-vlcli-fi-technology-market-worth-613802-million-by-2018-186272641.html.