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How does LiFi work exactly?

How LiFi works and how it can improve our lives.

The internet as it is now has become as ubiquitous as indoor plumbing. It has become so ubiquitous that we become fascinated by places without an internet connection or even a WiFi signal. Furthermore, what used to be labeled as a form of luxury has now become a necessity to live normally in the modern world.

The internet has become so ingrained into modern society that if the entire internet stops working, the results could be catastrophic as a bulk of the world’s governments are dependent on the internet in order to provide basic functions. That is also discounting the fact that modern businesses rely heavily on the internet not only as a means of acquiring and doing business but also to perform many different day-to-day tasks that are crucial to the business.

Given the gravity and sheer importance of the internet, it continues to see growth in the demand for its use, contributing greatly to network congestions. This necessitates newer technologies in order to meet this growing demand and deliver better results. In exploring the possibility of alternatives, one such alternative tapped to replace the prevailing WiFi technology is LiFi.

 

Defining LiFi

The term LiFi, which is short for Light Fidelity, was coined by one of the pioneers in the technology, Professor Harald Haas during a TEDx TALK in the year 2011. It was named after its predecessor, and the currently prevailing technology, WiFi, which stands for Wireless Fidelity.

LiFi is one of the newest communication technologies that aim to improve upon current technology by making use of visible light communication as opposed to the radio waves used by WiFi. Its introduction actually serves a dual purpose as it aims to provide overhead illumination to households as well as facilitate the transfer of data.

The introduction of LiFi presents a new paradigm for optical wireless technology as it aims to provide connectivity within a localized environment while forgoing the use of fiber optic cables as a transfer medium for light. Instead, it makes use of overhead LED lighting commonly found in households as a medium of transport. Currently, the technology is able to achieve a maximum data transfer rate of 224 gigabits per second – the equivalent of downloading 18 HD movies every second.

 

How Does LiFi Work?

LiFi makes use of visible light through overhead lighting for the transmission of data. This is possible through the use of a Visible Light Communications (VLC) system for data transmission. A VLC system has two qualifying components:

  1. At least one device containing a photodiode in order to receive light signals; and
  2. A light source equipped with a signal processing unit for the transmission of signals.

The VLC light source can be in the form of a fluorescent bulb or a light emitting diode (LED). LED light bulbs are the most optimum VLC light source, however, since a robust LiFi system requires extremely high rates of light output. Fluorescent bulbs emit light in a much wider band of wavelengths, which makes it a relatively less efficient light source than LED. LED, on the other hand, is a light source that emits light in a very narrow band of wavelengths, making it a more efficient light source.

LED is also a semiconductor, which implies that it can amplify light intensity and switch rapidly. This is an important quality to look for in a VLC light source because LiFi relies on the constant stream of photons emitted as visible light for the transfer of data. When the current applied to the light source is varied slowly, the light source dims up and down, which makes it unsuitable as a source of light, not for the LiFi system, but as a device for household illumination. To strike a balance between VLC light source and household illumination, this current as well as the optical output is modulated at extremely high speeds, making it detectable by the photodiode device and converted back into electrical current, but unperceivable by the human eye. Once these signals are received and demodulated, they can now be converted into a continuous stream of binary data that contain videos, images, audio, text, or applications that are readily-consumable on any internet-enabled device.

Because LiFi technology is still in its relative infancy, there is still much room for growing innovation. One proposed innovation to the existing technology includes creating a bidirectional communication system similar to conventional broadband and WiFi. This can be done by interchanging visible light and infrared light from a photodetector, allowing connected mobile devices to send back data to the light source for an uplink. Another proposed innovation is the re-engineering of the multi-colored RGB LEDs to send and receive data on a wider range of signals than the single-colored phosphor-coated white LEDs.

 

Is There Really a Need to Replace WiFi?

Considering the vast applications of the internet on modern technology (and almost all basic government and daily functions cease to exist without it), perhaps there really is a need to come up with improvements to the existing WiFi technology. This is due to the various limitations in its usage of radio frequencies as a data transfer medium. These limitations include its limited coverage, security concerns over connectivity, restriction of use due to frequency interference, and congestion of networks.

 

Does LiFi Stand to Eliminate WiFi?

LiFi is seen as a suitable alternative to mitigate, or even eliminate, all of the limitations of WiFi for data networks. Many have also gone as far as to declare LiFi as the future of internet connectivity. But is it really? Does it make a case for having to eliminate WiFi entirely?

In order to see the merits of LiFi and answer whether or not it should replace WiFi, it is imperative that some aspects of these two technologies are compared to see how they stack up against each other.

Data Transmission Speeds

Tests conducted by pureLiFi, a company started by LiFi pioneer Prof. Roland Haas, over a controlled environment, revealed LiFi to produce speeds of over 100 Gbps. Some tests even revealed that it can deliver data for up to 224 Gbps. These speeds are clearly miles ahead of those produced by WiFi, which currently sits at a maximum of 100 Mbps. This is due to the fact that the visible light spectrum is 1,000 times larger than the RF spectrum, which is only about 300 GHz.

Energy Efficiency

In WiFi, the transmission of data requires having two radios for the transmission of radio waves. These radios communicate with each other continuously through RF transmitters installed within the radio and a baseband chip, which takes up a lot of energy just to discern data signals from the noise from several other devices using the same radio frequency. In contrast, LiFi makes use of overhead LED lights as a medium for data transmission. Because it only requires a light source and a photodiode to decode the light signals, the entire process of data transmission and communication requires lower overall energy. Plus, LED lights are used as opposed to other forms of light bulbs, making it a more efficient source of light.

Coverage

Because WiFi makes use of radio waves as a medium for the transfer of data, it boasts of a wider range of coverage as WiFi signals can reach distances up to 32 meters (although connections are often slow at those distances). This is because radio waves are able to pass through walls. This is perhaps the greatest limitation for LiFi since visible light cannot pass through walls, limiting the area of coverage to rooms where the LED transmitter is installed.

Security

The limited coverage of LiFi can also be seen as a good thing since it increases network security. Again, because LiFi signals cannot pass through walls, interference from outside forces is limited. This also makes it ideal for use in sensitive areas where remote piracy and hacking is prevalent. As such, it is suitable for use for areas involved in research and development, finance, defense, and even mass transport.

Data Density

One of the biggest limitations of WiFi is its vulnerability in areas with high congestion. The transfer of data within areas with a high volume of users tend to be slower than areas with lower volumes of users. On the other hand, LiFi is not subject to the same limitations and, in fact, works well in very dense environments. Especially in areas where many light bulbs are present, LiFi can still produce high speeds as each VLC light source can deliver the same speed, even with multiple users.

 

Conclusion

The benefits that you can gain from LiFi is immense. This is not to discount the fact that WiFi has certainly helped improve the quality of life exponentially as it helped pave the way for faster communication and the improvement of even the most basic societal functions. It has, however, succumbed to many different factors that have also affected its performance. These factors include congestion, limitations of use due to interference with other functions, and bandwidth saturation, which clearly exposes the shortcomings of this existing technology.
The introduction of LiFi is certainly a welcome one. Of course, with limitations in basic infrastructure, the total replacement of WiFi in favor of LiFi is next to impossible. However, what it does present is a viable option that can be used as an alternative especially in areas that are sensitive to the prevailing technology.

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