Think of scenes in movies where you see a character turning a flashlight on and off in bursts to relay a message to someone else in morse code. Li-Fi is a technology that works like that, only a lot, lot faster. And it’s your smartphone talking to a lamp with its light pulses. Confused? Intrigued?
What is Li-Fi Technology?
As the tagline of a leading Li-Fi company PureLiFi goes, Li-Fi is where
“Light becomes data.”
Li-Fi stands for Light Fidelity. It is a technology for wireless communication that utilizes light, in the infrared and visible spectrum, for the transmission of data at high speeds. Li-Fi has been described as fifth-generation (5G) communication technology.
Li-Fi can be characterized as falling under the broad category of Visible Light Communication (VLC). The fact that Li-Fi allows bi-directional transmission of data, ie; data can be communicated from a light source to a device and back, is one feature that sets it apart from other subsets of VLC.
History of Li-Fi
The origins of VLC, and by extension Li-Fi, can be traced way back in history to Graham Bell’s Photophone invented in 1880. The photophone was a wireless communication device that used a beam of light to transmit speech. It is thought to be the predecessor to fibre optic communication, and now to Li-Fi.
Li-Fi technology was pioneered by Professor Harald Haas and the term was first introduced to the world in his talk at TED Global 2011, “Wireless Data from Every Light Bulb.” Haas was even dubbed “Father of Li-Fi” for his work.
Although numerous companies are now working on experimenting on and commercializing Li-Fi, Haas and his team are responsible for most of the research that went into this technology.
In 2012, Haas co-founded a Li-Fi company called pureVLC Ltd., which was later rebranded as PureLiFi. They released Li-1st, the world’s first commercial form of Li-Fi technology the next year. In 2015, Li-Flame was released for mobile wireless communications, and in 2016 saw the first industrialized form of Li-Fi.
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How Does Li-Fi Work?
Li-Fi is a form of VLC, so by definition, it has a transmitter and a receiver and uses light for the transmission of data.
Li-Fi networks are bi-directional, which means that an uplink and a downlink can both be formed simultaneously between the transmitter and receiver. This is what makes it so suitable for internet communication. It is to be noted that Li-Fi isn’t a different way of getting internet, it’s a different way for deploying internet.
Working and Components of a Li-Fi System (Source: https://lifi.co/)
The two main components of a Li-Fi network are-
Light sources, including light fixtures already being used for illumination, as well as special light sources particularly made for the purpose, are used for the transmission of data in Li-Fi. LED lights are most suited for data transmission because of their reliability and efficiency.
Infrared detectors to detect signals from devices are also present to make both uplink and downlink possible. The light fixtures act as an access point for data and can be powered and supplied with data through methods like Power over Ethernet (POE) or Power-Line Communication (PLC).
The light source emits pulses of light for transmitting data, which can then be captured and decoded by a receiver. So wouldn’t it be creepy having flickering lamps all over the place? Not really. The thing is, the pulses would be emitted at a frequency of more than a million times per second, which is just too quick for our eyes to notice.
The lights don't necessarily need to be excessively bright either. In fact, they can be dimmed so low that they fall below the visible spectrum, and still serve their purpose. So just because you turn out the light in your bedroom to sleep, doesn't mean you need to cut off your internet connection too.
A Li-Fi enabled device has a receiver, which is a photodiode for detecting the signal contained within the light emitted by the transmitter. The detector captures the modulated pulses and converts them into data much like translating morse code.
To enable the flow of data in both directions, the devices are also equipped with infrared transmitters for sending data back up to the light source.
Li-Fi vs Wi-Fi
When many hear about Li-Fi for wireless communication, they may get confused and go, “Wait, don’t you mean Wi-Fi?” Li-Fi is like Wi-Fi’s smarter, younger, and less famous cousin of sorts.
While Li-Fi still remains a niche technology with limited applications, Wi-Fi is a household term. It is what we all rely on every day for our life-sustaining internet connections.
The difference between the both is that Li-Fi uses light where Wi-Fi uses radiofrequency. Ultimately, Wi-Fi and Li-Fi serve the same purpose. Li-Fi may even replace Wi-Fi one day.
Li-Fi is faster, more secure, encounters little or no interference issues even in high-density areas, and could potentially be available anywhere where there is a light fixture.
Here’s a comprehensive comparison between the two-
Li-Fi vs Wi-Fi
There are disadvantages to Li-Fi, one being that since light cannot pass through walls or opaque structures, connectivity is limited to devices that are directly within the line of sight of a light fixture. Or more accurately, devices that are directly or indirectly illuminated by the fixture, since reflected light can also transmit data.
Also, if we’re using existing light fixtures, and not lights with the capability to be dimmed beyond human visibility, the signal gets cut when the light gets turned off. Then there’s also the matter of a huge infrastructural disruption that would need to take place for mass scale setting up of Li-Fi.
Advantages of Li-Fi
Li-Fi technology is still in its infant stage, with research being done on how to overcome its deficiencies. So it would be more illuminating for us to focus on its benefits, to understand why Li-Fi technology is so important.
Overcoming Spectrum Crunch
You would be hard-pressed to find a home without internet access these days, and the amount of wireless traffic is increasing drastically each year. Since all of this operates on the radio frequency spectrum, there is the chance of simply not having enough of the spectrum left to allocate any more.
This is called the spectrum crunch, a phenomenon that describes a possible condition where the radio frequency spectrum becomes oversaturated. The closer we get to this, more and more interference occurs in our wireless communications, and our internet speeds would suffer.
So Wi-Fi simply cannot support the growing data demand, and that’s where Li-Fi comes in. The infrared and visible light spectrum, where Li-Fi operates, is around 2600x the size of the radio frequency spectrum.
You can operate in areas with a high density of transmissions without your connection speed suffering. This means a Li-Fi dependent future would be better suited to deal with the ever-growing amounts of data transmission that we are dealing with.
Tests have shown that Li-Fi can offer a data transmission speed of upto 224 GBps, though devices currently in use offer lower, but still impressive speeds. The high speed is also owing to the size of the light spectrum used in Li-Fi. Such widespread access to fast internet would be revolutionary.
Multipurpose and Sustainable
LiFi technology uses devices that hit two birds with one stone- it combines the functions of illumination and data communication into the same device. The same light fixture can both provide light and transmit data.
Li-Fi technology can also use existing light fixtures and infrastructure for the most part. Even where other types of light fixtures are used, replacing them with LED lights for Li-Fi is not a waste, as LED is more efficient anyway.
Li-Fi would also save a lot of energy and cost. This is because maintaining a Wi-Fi network over an area requires several devices including routers, modems, and signal repeaters to be kept powered all the time. Li-Fi uses lighting which we are already keeping on a lot of the time.
This also means Li-Fi could be used as a tool to bridge the digital divide by helping ensure that internet access is available to everyone regardless of their financial constraints. Setting up LiFi in public spaces like parks would be much more economical and practical than setting up free WiFi hotspots.
Light doesn’t travel through walls and other opaque objects. That means your data transmissions stay inside the rooms that you want them to stay in. Although the inability of Li-Fi to permeate physical barriers is a drawback in some ways, it also means that absolute security of your connection is ensured.
For some hacker to even try to penetrate your network, they would need to be in a place illuminated by your LED transmitters, and not just anywhere within a radius of several meters, as is the case with Wi-Fi.
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Applications of Li-Fi
Our future may be Li-Fi suffused, where there is data flowing through every street lamp on the road and even the light in your bathrooms. But right now Li-Fi is being employed more for particular applications, where the particular features of Li-Fi have proven advantageous.
Let’s look at some of the applications of Li-Fi that merit attention-
Li-Fi is immune to electromagnetic interference. This makes it ideal for applications in hospitals, as Li-Fi does not interfere with devices that operate using radio frequencies. The speed and ubiquitousness of Li-Fi also help in real-time patient monitoring, seamless communication, etc.
Similarly, in aircrafts, the use of Li-Fi for communication is beneficial as there will be no interference to the radar system or other devices operating on radiofrequency. Providing internet connectivity in flights is also something that is greatly encouraging to passengers.
Defence, R&D, and Finance Sectors
Li-Fi provides a level of security that is crucial for these sectors and hence is being increasingly employed in them.
The ability of Li-Fi to provide high speeds even in high-density areas makes it optimal for places like universities and office buildings, where everyone is using wireless communication all the time.
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The fully automated smart homes of the future would have internet connectivity in every nook and cranny, connecting devices all over the house, forming a complete ecosystem within four walls. The use of Li-Fi can help in ensuring security, interconnectedness, and ubiquitous accessibility within the smart homes of the future.
Other applications of LI-Fi technology include augmented reality, retail, factory automation, driverless cars, etc.
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Future of Li-Fi Technology
Companies working on Li-Fi technology include-
Examples of some of the interesting Li-Fi products commercially available on the market at present are-
Lifi-XC: A Li-Fi dongle from PureLifi.
Kitefin: A military-grade, deployable Li-Fi for defence applications, also from PureLifi.
MyLiFi Pro: A Li-Fi supported desk lamp from Oledcomm.
The list is growing consistently. Still as of now, Li-Fi remains a niche technology, not popular among the masses. But that is bound to change soon.
Since its introduction, Li-Fi has been popularized as the technology that would one day replace Wi-Fi and bring forth a new 5G era. This paradigm shift in wireless communication that Haas envisioned in his 2018 paper is very much a possibility, it simply has not arrived yet.