Using lighting to stream data

Image credit: University of Edinburgh


When is technology development ever going to slow down? Just when you thought that we had high-speed wireless communication all sorted, somebody comes up with an idea that is potentially better – a technology that allows LED lighting to become internet and broadcast data transmitters, creating a new form of high-speed, optical wireless communication that leverages the visible and infrared (IR) light spectrum. This new form of transmission could be of use within the broadcast and media environment.

Back in 2011, in a world where the space for radio frequencies was already becoming over-saturated, University of Edinburgh research professor of mobile communications, Harald Haas, discovered something amazing – Light Fidelity (LiFi). This is a way and means of sending and receiving data using the modulation of light at frequencies that are imperceptible to the human eye, and it emerged that LED lighting was the perfect medium to develop the technology around.

Because LEDs are semiconductors, they can turn on and off up to a million times per second, enabling the diodes to send data quickly. In professor Haas’s Li-Fi installation, a digital signal processor integrated (or attached) to an LED driver takes data from a network, server or the internet and converts it into a digital signal—basically a sequence of discrete voltage levels. The LED driver in each fixture converts the digital signal into a photonic signal, transmitting it at a very high frequency as an Orthogonal Frequency Division Multiplex (OFDM) signal.

OFDM signals are also employed in 4G LTE, 5G and most Wi-Fi technologies because they use many small-bandwidth channels collectively, rather than a single large-bandwidth channel. The decoder on the receiving device—say, a computer or smartphone—then translates the OFDM signals into data for the user. The radio spectrum allotted for wireless communications spans only 300 gigahertz, while the visible light spectrum spans 300 terahertz, from red light at 400 terahertz to violet at 700 terahertz. Thus, light has 1,000 times more frequency available for wireless communications than radio. Li-Fi has the potential to achieve much higher data rates than we can currently achieve using Wi-Fi, with speeds of tens of gigabits per second having been achieved under controlled settings in the lab.

Unlike Wi-Fi, Li-Fi transmits data to devices via direct and incident light without risk of disrupting sensitive electronics, such as those found in hospitals or on airplanes. And because Li-Fi is directional, requiring a line of sight between the transmitter and the receiving device, it cannot be hacked. Li-Fi’s directionality also reduces the risk of interference with other devices vying for a connection, so co-channel interference, a source of noise, and electromagnetic radiation from the simultaneous use of mains electricity and wireless technology, which exist in radio waves, are absent in Li-Fi, making it a very reliable technology in terms of stability.

Apart from the obvious home-use advantages, technology researchers are looking at developing Li-Fi as means of providing network communications in television production studios and for OB van setups in stadiums. Developers have already tested the technology to replace traditional Wi-Fi in aircraft with great success. It’s being tested in vehicles to communicate with one another via front and back lights to increase road safety and integrated into streetlights and traffic signals to provide information about current road situations to users’ smartphones.

Li-Fi can be used anywhere that can be outfitted with wireless communications and electric lighting: commercial buildings, retail environments and smart cities for in-vehicle data transmission. As IoT (Internet of Things) and smart applications gain traction, Li-Fi offers the omnipresent wireless connections that these devices and applications need. Along with its use in bi-directional internet communications, Li-Fi holds promise in cataloguing and entertainment applications. Toric and Luciom, a French VLC company acquired by Philips Lighting, refer to these three respective applications as Li-Fi Internet, Li-Fi Tag, and Li-Fi Broadcast categories. Li-Fi Tag uses a router to broadcast the same tag repeatedly, for example, to confirm the specific row and shelf of a product in a store or distribution centre. The data flows one way from the emitter to the receiver, such as a device used for tracking inventory. Li-Fi Broadcast uses a router to transmit data, videos, music and shopping coupons one-way to consumer devices, such as smartphones.

Li-Fi has already been developed as an integral part of the new 5G network. Though Li-Fi technology is prohibitively expensive in its early stages, it isn’t stopping tech developers from seeing its advantages – and the more money that’s put into development, the cheaper the end cost will become. An Australian start-up company is developing and integrating Li-Fi into their lighting kits for film and television production. Essentially, the individual lighting components all communicate with each other via the light network that they produce; the rigger adjusts settings on a smartphone app and each light self-adjusts accordingly.

Along with all these benefits, there are also some disadvantages of a Li-Fi connection. Since it uses visible light to transmit data, Li-Fi would be rather useless in conditions where there is no light. That means no Internet while lying in your bed at night. Similarly, if you have a Wi-Fi router installed in one room of your house, you can connect your devices sitting anywhere in the house – but this is not the case with Li-Fi. Since visible rays cannot pass through walls, you have to be in the immediate vicinity of the source of light to access the Internet on your device, which may not sound particularly convenient to many people.

Whilst the technology is not here to replace Wi-Fi, a recent article posted on Tweet Tech stated that Li-Fi is on track to become a $113bn industry in 2022. If you really want to see the advantages of Li-Fi you need to visit Dubai. The city became the first smart Li-Fi city in the world last year to roll out the internet, live stream television channels and run the city’s infrastructure programme on the massive street lighting grid.

Li-Fi is impressive technology that, from a tech professional’s perspective, should be something to embrace and not something to be wary of. As Plato once said “We can easily forgive a child who is afraid of the dark; the real tragedy of life is when men are afraid of the light.”