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Li-Fi: Using Visible Light for Lightning Fast Data Transmission

Submitted By: 

Neha Rastogi

The ubiquitous nature of the internet is probably a major reason for making our lives the way it is today. In the present scenario, it has become a necessity of the modern world. Not only it connects all the devices ranging from gaming consoles to digital cameras but it even allows to remotely operating the electronics appliances through IoT. However, the capabilities of the internet are not limited to over knowledge regarding the usage of Wi-Fi. Another superior technology of Li-Fi is ultimately going to change our perception of the internet.

As we know that Wi-Fi is a commonly used wireless technology which uses radio waves to connect devices to the internet but with the growing demands and increase in the network congestion, the present technology won’t be able to deliver the desired results for a long time. Consequently, while exploring the possibility of alternate choices the term ‘Li-Fi’ was devised. 
 
Here we are going to illustrate the concept of Li-Fi technology, how does it work, and how is it different from the conventional Wi-Fi technology.
 
Li-Fi: Using Visible Light for Lightning Fast Data Transmission
 
Li-Fi: Using Visible Light for Lightning Fast Data Transmission

What is Li-Fi?

Li-Fi, a short form for Light Fidelity, is a wireless technology that makes use of visible light communication instead of radio waves. In this, common household LED bulbs can be utilised to allow data transfer with a speed of up to 224 gigabits per second, which equates to downloading around 18 movies each of 1.5 GB in every single second. 
 
This term was coined by Professor Harald Haas during a TED TALK in the year 2011. Basically, with this technology, people will be able to use light bulbs and solar cells as wireless routers for transmitting data. He even set up a company named pureLiFi in 2012 and aims to be the world leader in Visible Light Communications technology.
 
Li-Fi: Using Visible Light for Lightning Fast Data Transmission
 
Diagram Depicting Li-Fi Connections (Image Courtesy: ScienceAlert)
 
However, if we look back at the History, visible light communication has been in use since ages. In fact, the first demonstration of this technology took place in 1880, when Alexander Graham Bell invented a photophone device which could transmit voice over several hundred meters by using sunlight. So the advent of Li-Fi technology in a way indicates the comeback of tried and tested method used for data transmission in fiber-optic cables. Also, it carries a new sophistication that can be universally adopted so as to meet the demands for a high-speed futuristic internet. 

How does it Work?

Howe Li-Fi Works
Howe Li-Fi Works (Image Courtesy: purelifi)
 
All the existing wireless technologies utilise different frequencies on the electromagnetic spectrum. While Wi-Fi uses radio waves, Li-Fi hitches information through visible light communication. Given this, the latter requires a photo-detector to receive light signals and a processor to convert the data into streamable content. As a result, the semiconductor nature of LED light bulbs makes them a feasible source of high-speed wireless communication. 
 
So, how does it work? Let’s look at the working of Li-Fi:
 
When a constant current source is applied to an LED bulb, it emits a constant stream of photons observed as visible light. When this current is varied slowly, the bulb dims up and down. As these LED bulbs are semiconductor, the current and optical output can be modulated at extremely high speeds that can be detected by a photo-detector device and converted back to electrical current. 
 
The intensity modulation is too quick to be perceived with the human eye and hence the communication seems to be seamless just like RF. So, the technique can help in transmitting high-speed information from an LED light bulb. However, it’s much simpler, unlike RF communication which requires radio circuits, antennas, and complex receivers.
 
Li-Fi uses direct modulation methods similar used in low-cost infrared communications devices like remote control units. Moreover, infra-red communication has limited powers due to safety requirements while LED bulbs have intensities high enough to achieve very large data rates. 

Wi-Fi vs Li-Fi

Wi-Fi vs Li-Fi
Wi-Fi vs Li-Fi (Image Courtesy: Bloomberg)
 
Now that we know what Li-Fi is and how it works, the question is where it stands when compared to Wi-Fi. In order to get an understanding as to which one is superior, let’s take a look at certain aspects of both the technologies:

Speed: 

Li-Fi can possibly deliver data transfer speeds of 224 gigabits per second which clearly leaves Wi-Fi far behind. As per the tests conducted by pureLiFi, the technology produced over 100 Gbps in a controlled environment. Moreover, the visible light spectrum is 1,000 times larger than the 300 GHz of RF spectrum which helps in gaining high speed. 

Energy Efficiency

Usually, Wi-Fi needs two radios to communicate back and forth which takes a lot of energy to discern the signal from the noise as there may be several devices using the same frequency. Each device has an RF transmitter and baseband chip for enabling communication. However, as Li-Fi uses LED lights, the transmission requires minimal additional power for enabling communication. 

Security

One of the main differences between Wi-Fi and Li-Fi is that the former has a wider range (typically 32 meters) and can even be accessed throughout different portions of a building, however, the latter can’t penetrate through walls and ceilings and hence it’s more secure. 
Although that would mean fitting a separate LED bulb in all the rooms, yet the technology can be ideal for sensitive operations like R&D, Defense, Banks, etc. So, in a way, it’s not subject to remote piracy and hacking as opposed to Wi-Fi. 

Data Density

Owing to the interference issues, Wi-Fi works in a less dense environment while Li-Fi works in a highly dense environment. The area covered by one Wi-Fi access point has 10s or 100s of lights and each LiFi light can deliver the same speed or greater than a Wi-Fi access point. Therefore, in the same area, LiFi can provide 10, or 100, or 1000 times greater wireless capacity.

Li-Fi Technology Projects

With the ever increasing demand for data transfer and the high congestion on existing Wi-Fi networks, the need to develop an alternative for high-speed internet has become crucial. As a result, many companies are working on the technology for an easy access and superior data transfer quality.
 
Mentioned below are some companies that are involved in developing and exploring the possibilities of Li-Fi as a futuristic internet service:

pureLiFi

It was founded by Professor Harald Haas and Mostafa Afghani in the year 2012. The startup has tested its technology with customers like Cisco Systems and British Telecommunications. It has also partnered with French light maker Lucibel to introduce Li-Fi equipped overhead lights. 

VLNComm

Mohammad Noshad and Maite Brandt-Pearce founded VLNComm in the year 2013. Backed by the U.S. Department of Energy and National Science Foundation, the team is in partnership talks with U.S. government agencies. Their latest overhead light prototype is as fast as 25 Mbps while the next one is expected to reach 100 Mbps owing to the advances in coding, modulation, and signal processing.

Velmenni

It’s a company founded by Deepak Solanki and Saurabh Garg in 2012. The team has developed a credit-card-size prototype router capable of converting off-the-shelf LED lights into Li-Fi transmitters. It’s also developing Li-Fi applications for airplane cabins and cockpits as well as hardware for outdoor use.

Eindhoven University of Technology

The team of researchers at this university led by Joanne Oh has developed a Li-Fi system that uses harmless infrared rays. The data capacity of the system is 40Gbit/s per day because of the wavelengths measuring 1500 nanometers and more. As per Joanne, the team even managed speeds of up to 42.8 Gbots/s over a distance of 2.5 meters. 
 
Other notable names include i2cat, ByteLight, Basic6, etc. Besides, some other established organisations have also shown interest towards working on the technology. The technology has been tested by a UAE-based telecommunications provider. Apart from this, if market reports are to be believed, Apple may build future iPhones with Li-Fi capabilities.

Conclusion

Undoubtedly Wi-Fi has been a boon for all of us but factors like increasing congestion, interference with sensitive equipment and saturation of the bandwidth clearly indicate the shortcomings of the current technology. Li-Fi, on the other hand, digitizes the world by manipulating light in order to transmit information using low-energy technology. Besides, features like high-speed data transfer and privacy further favour the use of Li-Fi over Wi-Fi. 
 
Although it will be impossible to replace Wi-Fi with Li-Fi because of the existing infrastructure, it surely can emerge as an imperative option for certain businesses, airliners, hospitals, etc. So, basically, more than choosing one of the two options, it’s more like using both the technologies as per the usage requirements.