Li-Fi: Is It Better Than Wi-Fi? And Proper Substitute?

Wireless Fidelity, or simply Wi-Fi, standardized under IEEE 802.11, revolutionized the way we connect and access the internet. It allowed ubiquitous connectivity and a declining dependence on wired Ethernet connections and modems.

Wi-Fi has become an integral part of our life with our houses, workplaces, leisure centers, even public transportation facilities, among others, equipped with dedicated access points that allow us to connect to the internet wherever we are. The broad range of electronic devices, from smartphones all the way to electric home appliances, are currently equipped with dedicated chips and transmitters, allowing seamless connections among them.

Wi-Fi has also constituted a complementary technology for cellular wireless communication standards such as 5G. It provided a seamless coverage extension, particularly allowing proper connectivity in indoor and underground spaces where the signal received from transmission towers is relatively weak. The two wireless transmission technologies were even used concurrently to increase the download speeds providing mobile subscribers with a better user experience without the need to upgrade the network or their data plan.

Given all this, we clearly can’t live in this era without being connected to our surroundings, and in particular, it is fair to say, we clearly can’t live without Wi-Fi. Therefore, would it be easy for a new technology to score a win in a market largely dominated by Wi-Fi? It is certainly an uphill task, yet not unfeasible if it can match Wi-Fi in terms of the holistic experience it provides to the users.

A New Promising Technology

Wi-Fi has solved a known problem for many households, that of guaranteeing the last mile connection to the end-user. However, a new technology emerged, taking cues from its older sibling but utilizing a different medium for transmission. Dubbed light fidelity or Li-Fi, the new technology tries to make use of installed lighting systems to transmit data back and forth to the users, ensuring the required two-way connectivity. The concept was introduced by Prof. Harald Haas from the University of Edinburgh in a TEDGlobal talk in 2011.

The research idea soon matured enough and entered into commercialization through the first dedicated company PureLiFi, established by Haas himself. The company now offers a myriad of products that allow connectivity through light sources using practically any device. Their latest offering, Kitefin, enables solutions for the defense. The technology is gaining worldwide momentum, and the Li-Fi market is expected to achieve a staggering compound annual growth rate of 69.7 percent over a period of five years and potentially exceed USD 8 billion by 2030.

The working mechanism of Li-Fi is relatively simple. Instead of using radio waves, the Li-Fi transmitter tries to change some properties of the emanating light wave according to the data being sent, a process known as modulation. For example, the data could be encoded in the intensity of light. By changing the intensity of the light, at a rate the eye cannot perceive, data can be sent to the intended receiver. Several other transmission schemes are present such as using an array of light sources to encode the data or even using a certain color combination from red, green, and blue light-emitting diodes (in general, any color can be generated through a red, green, and blue combination).

Although not to the extent of Wi-Fi, Li-Fi allows mobility as multiple light sources can be added to a single network enabling the user to move around without losing connectivity.
Obviously, the light should always be on for Li-Fi to work. Well, not exactly. As a matter of fact, light can be dimmed to a certain extent that will appear dark and still be used to transmit data.

But Why Li-Fi?

The benefits of using Li-Fi are numerous. The properties of this technology iron out several problems resulting from the use of Wi-Fi networks.

• Spectrum

Why Li-Fi and why it should replace Wi-Fi is a recurrent question, yet, the first obvious answer is a spectrum, the most expensive resource for communication systems. The radiofrequency (RF) spectrum, which is between 3 kHz and 300 GHz, has been lately suffering from a severe crunch. The available resources are certainly not enough to accommodate an increasing number of users and wireless technologies. The frequency allocation map used by regulatory agencies around the world is devoid of empty spaces, pushing entities working on the development of future wireless standards to look for new avenues.

Li-Fi relies on visible light communication (VLC) concepts, that is, as the name implies use visible light for transmission. The available spectrum for use is then around 6 THz, that is, around 12000 times the size of the crowded RF spectrum. This paves the way to tremendous new opportunities in developing new technologies and accommodating a larger number of users while guaranteeing an impressive quality of experience with high data rates and significantly low latencies.

• Safety

A large debate in the medical field relates to the effects of RF electromagnetic transmission on the health of mobile subscribers who are constantly exposed to radiations originating from nearby transmission stations. Wi-Fi, among others, uses the same transmission technique, and related users are exposed to the same issues. Li-Fi, on the other hand, relies on the much safer VLC paradigm.

As mentioned earlier, data is encoded by varying the properties of light signals, an extremely safe approach as per the general consensus (especially that illumination changes are very fast to induce a perceivable flickering). The safety of Li-Fi systems makes it an excellent candidate for critical environments such as hospitals. PureLiFi conducted a joint project with collaborators in Italy to use Li-Fi technology in the healthcare industry providing wireless connectivity and a data management platform through the existing lighting infrastructure. The safety of Li-Fi has also made it an excellent candidate to be used in the aviation industry.

Unlike the big hustle caused by the potential interference between the newly deployed 5G network in the USA and the altimeters used by airplanes, Li-Fi would blend in perfectly, mainly because visible light systems won’t interfere with radio wave-based radars.

• Security

Wi-Fi networks have, in general, been prone to security breaches with attackers and hackers exploiting vulnerabilities to perform denial of service attacks or gain access to critical data by eavesdropping on less secure Wi-Fi connections. Intrinsically, Li-Fi systems provide a high level of security as the data transmission is confined to the illumination range of the light source. Furthermore, light cannot go beyond the room where it is emanating from as it cannot traverse thick walls. Hence, any unauthorized access should come necessarily from the same location where communication is taking place.

• Interference

Another problem with Wi-Fi and RF-based wireless technologies, in general, is interference. The spectrum crunch has led to inevitable interference between wireless technologies and among users using the same technology. The issue stems from the reuse of the limited resources to accommodate a large number of users. Another inherent property of Li-Fi is the significantly reduced interference due to the confined transmission area.

Towards a Synergistic Convergence?

The confrontation between light and wireless fidelities shouldn’t, in fact, be pictured as a survival battle where Li-Fi would potentially overhaul Wi-Fi. The developed synergy between cellular wireless technologies such as 4G or 5G and Wi-Fi and the gains obtained from such coexistence give all the plausible reasons to further integrate Li-Fi with these technologies. In addition to providing last-mile connectivity, mainly indoor, Li-Fi could provide a highly coveted load balancing solution where a load of subscribers can be optimally and equitably distributed between different technologies. It could also contribute to satisfying the performance requirements of constraining use cases such as gaming, high-resolution video streaming, or even more critical applications related to the tactile internet (e.g., remote surgery).

Summary

It is very hard to say whether Li-Fi or Wi-Fi is better as each technology has its pros and cons. However, it is relatively easy to conclude that ensuring a proper synergy among different wireless technologies is crucial for the viability of future wireless networks.

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