LiFi vs WiFi: Key Differences in Wireless Technologies

Introduction

Wireless communication technologies have revolutionized how we connect and share data. Two prominent technologies in this domain are LiFi and WiFi, both offering unique ways to transmit data wirelessly. While WiFi has become a household name, using radio waves for connectivity, LiFi is an emerging technology that uses light to transfer data.

In this comprehensive comparison of LiFi vs WiFi, we explore the fundamental differences between them, focusing on their operating principles, speed, security, and real-world applications. Understanding these distinctions can help you choose the best wireless solution for your specific needs.

The purpose of both LiFi and WiFi is to provide wireless connectivity to devices, allowing them to access the internet, share data, and communicate with each other. They simply use different mediums and technologies to achieve these goals.

LiFi utilizes visible light communication (VLC) to transmit data through LED light bulbs. WiFi operates using radio frequency (RF) waves to establish wireless connections between devices (i.e., stations or clients) and networks (i.e., WiFi routers or access points). LiFi stands for Light Fidelity, whereas WiFi stands for Wireless Fidelity.

What is LiFi Technology?

As mentioned, LiFi (Light Fidelity) uses light as a medium for wireless data communication. It uses LED light bulbs as devices to transmit data wirelessly using visible light.

By modulating the intensity of light at extremely high speeds, LiFi can transmit data to compatible receivers such as smartphones or laptops equipped with light sensors. LiFi is advantageous in specific applications where traditional wireless technologies like WiFi may not be suitable or secure to use.

The following are features of LiFi technology, as depicted in the figure above:

• LiFi (Light Fidelity) works based on the VLC (Visible Light Communication) principle.
• It consists of two main components to drive the internet, namely a LED Lamp and a Li-Fi Dongle.
• Li-Fi transmits data using light intensity modulation.
• It uses LEDs at transmit ends and Photo-detectors at receive ends. The LiFi dongle uses photo-detectors, as shown in the figure. Here, LEDs are connected with an internet server via a lamp driver for internet connection.
• It uses light with a wavelength ranging from 380 nm to 780 nm for data communication between LEDs and photo detectors.
• The LiFi system supports three modes: peer-to-peer, star, and broadcast.
• LiFi system uses modulation schemes such as OOK, VPPM, and CSK.
• The PHY and MAC layers of the LiFi system are defined in the IEEE 802.15.7-2011 standard.
• LiFi technology is used for various applications, which include street lights, sign boards, internet, etc.
• It transfers data very rapidly and securely due to the LOS (Line of Sight) operation of optical signals.

Advantages of LiFi

Following are the advantages of LiFi technology:

• Li-Fi can achieve extremely high data transfer rates compared to traditional WiFi.
• LiFi offers enhanced security as visible light does not pass through walls. Moreover, it has a limited range and works in Line of Sight (LOS) mode, which adds an extra layer of privacy to the data being transmitted.
• LiFi uses the visible light spectrum that does not cause any EM (Electro-Magnetic) interference.
• It reduces RF congestion by using an un-utilized visible light spectrum.
• LiFi technology uses visible light, which is non-ionizing and considered safe for human health, unlike RF radiation used in WiFi.
• It uses LED bulbs for data transmission, which are more energy efficient compared to traditional light sources.

Disadvantages of LiFi

Following are the disadvantages of LiFi technology:

• It has a limited range and requires clear LOS for its operation.
• LiFi signals can be blocked easily by physical obstacles such as walls, furniture, or even human bodies. This poses a challenge in offering uninterrupted connectivity in complex environments.
• LiFi-based internet systems require the installation of LED lighting infrastructure and compatible receiver devices. Hence, the initial setup costs may be higher compared to traditional WiFi infrastructure.
• LiFi systems can be affected by external light sources such as sunlight and other bright light fixtures.
• LiFi compatible devices and its adoption are limited compared to the already established WiFi technology.

What is WiFi Technology?

As mentioned, WiFi (Wireless Fidelity) uses Electro-Magnetic waves at different radio frequencies for wireless data communication. It allows devices like smartphones, tablets, laptops, smart TVs, and IoT devices to connect to the internet and local area networks (LANs) without the need for physical cables.

In a WiFi network, wireless routers emit radio waves within specific frequency bands. Devices equipped with WiFi adapters or SoCs can detect and connect to these networks, enabling wireless communication and internet access. The router is connected to the internet via a wired connection (e.g., DSL, fiber, or cable modem) and acts as a gateway between the internet and connected devices.

Following are the features of WiFi technology, as depicted in the figure above:

• It consists of two important devices, namely, a WiFi router or Access Point (AP), a WiFi dongle, and WiFi stations.
• As shown, a WiFi AP or Router is connected to the internet using a broadband cable or with a cellular network. All the WiFi-compatible mobile phones, tablets, or laptops are connected with the AP (or router) to obtain internet.
• WiFi networks operate in either of two modes: ad hoc (i.e., BSS - Basic Service Set) and infrastructure (i.e., ESS - Extended Service Set).
• In a BSS, WLAN compliant stations (i.e., STAs) communicate directly. In an ESS, WLAN compliant STAs communicate with APs (Access Points) to access the internet.
• WiFi supports different speeds and coverage ranges as per the implemented standard in the devices (STAs, APs). 802.11a supports up to 54 Mbps, 11b up to 11 Mbps, 11n supports 72 Mbps/150 Mbps as per BW (20MHz/40MHz), 802.11ac wave-1 supports up to 1.3 Gbps (80MHz, 3 streams, 256QAM), 802.11ac wave-2 supports up to 3.5 Gbps (160MHz, 4 streams, 256QAM), etc. The distance coverage of 70 meters (indoor) to 250 meters (outdoor) can be achieved.
• WiFi networks operate in different frequency bands: 2.4 GHz, 5 GHz.
• The PHY and MAC layers of WiFi systems are defined in IEEE 802.11 standards. There are various versions of 802.11 which include 11a, 11b, 11g, 11n, 11ac, etc.

Advantages of WiFi

Following are the advantages of WiFi technology:

• WiFi networks cover larger areas, which makes them suitable for providing internet access in homes, offices, public places, and other environments with multiple users having varied devices.
• Most modern devices such as smartphones, tablets, laptops, smart TVs, and IoT devices are equipped with WiFi capabilities, hence ensuring broad compatibility and ease of use.
• WiFi networks can support multiple devices simultaneously.
• WiFi networks can easily be upgraded to accommodate more users or to increase coverage. This makes them adaptable to changing needs.
• WiFi operates in Non-LOS (Line of Sight), unlike LiFi.
• WiFi networks can easily be interfaced with existing wired networks, which provides seamless connectivity between wired and wireless devices.

Disadvantages of WiFi

Following are the disadvantages of WiFi technology:

• WiFi networks operating in crowded areas or in the presence of other wireless devices may experience interference. This leads to reduced performance and slower data transfer rates.
• WiFi networks are susceptible to security threats if not properly secured with encryption and strong passwords.
• Physical obstacles like walls, furniture, or other objects can block WiFi signals, which leads to dead spots and reduced connectivity in certain areas of home or office. This problem can be avoided by installing a WiFi repeater or adding an extra router.
• Modern WiFi standards (802.11ac and 802.11ax) offer higher data transfer rates, but it cannot be matched with speeds delivered by LiFi.
• WiFi devices consume more power, which potentially impacts the battery life of mobile devices.
• Some studies raised concerns regarding the potential health effects of RF radiation from WiFi devices, although the evidence is inconclusive.

Difference between LiFi and WiFi

Let us compare LiFi vs WiFi with respect to various features and their respective advantages and disadvantages in tabular form.

The following table provides a comparison between LiFi vs WiFi speed with other wireless technologies such as IrDA, Bluetooth, and NFC.

Conclusion

The difference between LiFi and WiFi lies in the technologies they use to transmit data: LiFi with visible light and WiFi with radio frequencies. LiFi vs WiFi comparisons highlight that while LiFi offers faster, more secure, and interference-free communication in certain environments, WiFi remains the go-to technology for broader coverage and device compatibility. Each has its advantages and is suited to different use cases, with LiFi excelling in specific, high-speed scenarios and WiFi offering more widespread utility.