Li-Fi: How this LED Technology works and differs from Wi-Fi


Li-Fi Technology has made it possible to get cheaper and faster internet access than wi-fi via LED Light Bulbs with breakthrough data transmission method – here’s how!

Li-Fi vs Wi-Fi technology

Every one of us have used and using Wi-Fi to access wireless internet. However, the biggest problem faced by the Wi-Fi users (most of the time) is that of slow Internet access speeds. Undue interference from other devices/equipments and loss of signal quality over the air are the main reasons for this issue. Keeping in mind these drawbacks, a new technology has been invented that allow use of the internet at the speed of light. It’s called Li-Fi (Light Fidelity) and it uses light from LEDs as a medium to deliver high-speed wireless internet. Researchers have already achieved data rates of more than 10 Gbit/s with Li-Fi, which is 250 times faster than the fastest existing broadband!

What is Li-Fi?

Li-Fi stands for Light Fidelity and basically it’s a visible light communication system that uses LED lights to transmit data with out wires. Invented by a German physicist named Harald Haas, Li-Fi has got a much broader spectrum for transmission compared to conventional methods of wireless communications that rely on radio waves. To be specific, Li-Fi uses visible light spectrum which is 1,000 times larger than the Radio spectrum. That means, Li-Fi network virtually has an unlimited capacity and it also promises to be cheaper, faster and safer alternative to radio wave communication. A possible Li-Fi environment in an office is shown in the figure below.

this is how LI-Fi wireless technology works

Li-Fi system connecting devices in a room


Construction of Li-Fi system

The Li-Fi system basically comprises of two main parts – the transmitter and the receiver. A high brightness white LED is used as the transmitting element and a silicon-based photo-diode with good sensitivity to visible light waves as the receiving element.

Switching the LEDs on and off can make them generate digital strings with different combination of 1s and 0s. New data streams can be encoded by simply varying the flickering rate of the light. In this way, the LEDs work as a sender by modulating the light with the data signal. However, the LED output will appear constant to humans because they are made to flicker at a phenomenal speed (millions of times per second) and it’s impossible for human eye to detect this frequency. Data rate of more than 100 Mbps can be achieved with high-speed LEDs by employing various multiplexing techniques. And this rate can be further increased to as high as 10 Gbps via parallel data transmission using an array of LED lights with each LED transmitting a different data stream. (A data rate of 10 Gbps means you can download a full HD movie in a mere 30 seconds!)

The Li-Fi product (or the emitter system) comprises of four primary sub-assemblies:

  • Bulb
  • RF power amplifier circuit (PA)
  • Printed circuit board (PCB) and
  • Enclosure
li fi technology abstract

Block diagram of Li-Fi sub assemblies

The Printed circuit board (PCB) controls the electric input and output of the lamp, and houses the microcontroller whose task is to manage all functions of the lamp. A radio-frequency signal produced by the power amplifier is directed into the electric field of the bulb. As a result of the high concentration of energy in the electric field, the contents of the bulb will get vaporized into a plasma state at the bulb’s centre. And this controlled plasma in turn will produce an intense source of light. All of these sub-assemblies are enclosed in an aluminum case as shown in the above block diagram.

Li-Fi bulb sub assembly

Li-Fi Bulb sub-assembly

Li-Fi Bulb sub-assembly

The bulb sub-assembly also constitutes a main part of the emitter. As it can be seen from the above figure, it comprises of a sealed bulb embedded in a dielectric material, which serves two purposes: one, it acts as a waveguide for the radio-frequency energy transmitted by the power amplifier, and two, it acts as an electric field concentrator that focus the energy into the bulb. The collected energy will rapidly heat the material in the bulb to a plasma state, eventually emitting high intensity light of full spectrum.

Working of Li-Fi

High brightness LEDs are the heart of Li-Fi technology. The logic is very straightforward. If the LED is ‘ON’, binary data ‘1’ is transmitted and if the LED is ‘OFF’ binary data ‘0’ is transmitted. Plus, these LEDs can be switched on and off at high speeds, giving huge opportunities for transmitting data through LED lights.

how does li-fi wireless technology work

Block diagram illustrates how Li-Fi technology works

The overall working principle of Li-Fi is also quite simple. There is a light emitter i.e. an LED at one end and a photo detector (light sensor) on the other. The photo detector will register a binary ‘1’ when the light is on and a binary ‘0’ when the light is off. Thus flashing the LED numerous times or using an array of LEDs (perhaps of a few different colors) will eventually provide data rates in the range of hundreds of MBs per second. A block diagram of the Li-Fi system is given above.

For processing the data, the LED bulb will hold a micro chip. It will convert and encode the data into light by varying the flickering rate of the light. The receptor or the photo detector will receive these light signals, and then they will be amplified, processed and converted back to digital form which the machine can interpret.

An Infographic : Li-Fi – how does it Work ?:

working of lifi wireless communication technology


Li-Fi Vs Wi-Fi: Which is better?

It’s unbelievable! Just go through the comparison and see how Li-Fi beats Wi-Fi in every aspect.

lifi and wifi difference, compare lifi and wifi

Li-Fi Technology Vs Wi-Fi Technology

Both Wi-Fi and Li-Fi provide wireless internet access to users, and both the technologies transmit data over electromagnetic spectrum. The difference is: Wi-Fi uses radio waves for transmission, whereas Li-Fi utilizes light waves. And this very reason makes Li-Fi better, safer, and cheaper than Wi-Fi. The speed of the internet you get with Li-Fi is incredibly high. Plus, you need not to be in a particular Wi-Fi enabled region to have internet access. You can simply stand under any form of light – street lights, tube lights, lamps, etc. – and surf the internet almost anywhere in streets, shops, house etc.

Key benefits of Li-Fi over Wi-Fi:

More bandwidth: The visible light spectrum has 10,000 times more bandwidth than radio waves spectrum. Plus, it’s unlicensed and free to use.

High data density: Li-Fi has about 1000 times more data density than W-Fi. Because visible light don’t spread out or interfere with other electromagnetic waves.

High speed: Combination of low interference, high bandwidths and high-intensity output, help Li-Fi provide exceptionally high data rates. When the latest high-speed Wi-Fi standard, 801.11ac has a maximum speed of just about 867 Megabits/second, Li-Fi can boast a whopping speed of up to 3.5Gbit/s per color.

Cheaper: Li-Fi not only requires fewer components for its working, but also uses only a negligible additional power for the data transmission.

Safer: Visible light does not pose any health hazards to living beings. Also, unlike Wi-Fi, Li-Fi don’t create Electromagnetic Interference (EMI) problems, and so it can be used anywhere in any environment.

Securer: Li-Fi technology is far more secure than the old Wi-Fi. Light waves don’t travel through walls and hence people passing by will not be able to connect and piggyback off of your connection.

The comparison table below shows an overview of how Li-Fi and Wi-Fi compare in terms of various important parameters:

Li-Fi versus Wi-Fi

comapre lifi and wifi to find out the difference between and advantages over wifi and lifi wireless communication technology

Every technology has limitations, and Li-Fi is no exception. Some of the major drawbacks of Li-Fi are:

  • It requires a perfect line-of-sight to transmit data
  • Opaque obstacles on pathways can affect data transmission
  • Natural light, sunlight, and normal electric light can affect the data transmission speed
  • Light waves don’t penetrate through walls and so Li-Fi has a much shorter range than Wi-Fi
  • High installation cost

Still, Li-Fi technology has a great scope in future. The extensive growth in the use of LEDs for illumination indeed provides the opportunity to integrate the technology into a plethora of environments and applications.

Applications of Li-Fi

Smart controllable lighting: Any private or public lighting source such as street lights can be used as an internet hotspot – meaning the same infrastructure will monitor and control both lighting and data.

Mobile Connectivity: Mobiles, laptops, tablets, and other PDAs can easily connect with each other. The short-range network of Li-Fi can yield exceptionally high data rates and higher security.

Hazardous Environments: Li-Fi is intrinsically safe to use in hazardous environments such as petrochemical plants, nuclear power plants, mines etc. where Wi-Fi is prohibited.

Hospital and Healthcare: Unlike Wi-Fi, Li-Fi doesn’t emit any electromagnetic interference. And so it will not interfere with or by medical equipments like MRI scanners.

Aviation: Using Li-Fi, aircraft passengers can access high-speed internet via lights fitted over their seats. It can even be used to integrate the passenger’s smartphones with an In-flight Entertainment (IFE) system.

Underwater Communication: Li-Fi can also work underwater where Wi-Fi doesn’t work at all. Thus Li-Fi has thrown open a world of possibilities for military/navigation operations.

Vehicles & Transportation: New generation vehicles are coming with LED headlights and taillights. Street lights, signage and traffic lights are also shifting to energy-efficient LEDs. So, Li-Fi technology can be easily used for vehicle-to-vehicle and vehicle-to-roadside sensor communications for road safety and traffic management system.

Location Based Services (LBS): Li-Fi can enable precise location-specific information services like advertising & navigation, through which recipients can get relevant information in a timely manner and location.

Toys: Nowadays many toys come with LED lights and these can be used to establish wireless communications between interactive toys.

Li-Fi Products

A company called PureLiFi, co-founded by Professor Harald Haas, is into commercializing Li-Fi. In Q4 of 2014, they launched the world’s first Li-Fi network product called Li-1st in the market. It’s a point-to-point bidirectional communication system device that delivers great speed wireless data and security features.

Then to overcome the drawbacks of Li-1st, Pure LiFi launched another product called Li-Flame. It allows the user to roam inside the room from one corner to another without experiencing any interruption in the high-speed data stream.


Although there’s still a long way to go to make this technology a commercial success, it promises a great potential in the field of wireless internet. In fact, as per MarketsandMarkets analysis, the Li-Fi market is expected to be worth more than $6 billion by 2018. A significant number of researchers and companies are currently working on this concept, which promises to solve the problem of lack of spectrum space and low internet connection speed. Plus, it will also allow internet access in those places or fields where radio based wireless isn’t allowed. One thing’s for sure, Li-Fi is the future of mobile internet.

Video of Prof. Harald Haas demonstrating Li-Fi:

Student Corner: If you are student and want to include Li-Fi technology in your seminar topic  then these Li-Fi PPT and Li-Fi Doc will be helpful for you in making power point presentation.



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