LiFi vs WiFi | Difference between LiFi and WiFi

The purpose of LiFi and WiFi is to provide wireless connectivity to devices which allow them to access internet, share data and communicate with each other. They 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. wi-fi routers or access points). LiFi stands for Light Fidelity where as WiFi stands for Wireless Fidelity.

What is LiFi Technology ?

As mentioned LiFi full form is Light Fidelity which uses light as 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, Li-Fi 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.

Following are the features of LiFi technology as depicted in the figure-1.
• LiFi (Light Fidelity) works based on 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. LiFi dongle uses photo-detectors as shown in the figure-1. Here LEDs are connected with internet server via lamp driver for internet connection.
• It uses light with wavelength ranging from 380 nm to 780 nm for data communication between LEDs and photo detectors.
• LiFi system supports three modes viz. peer to peer, star and broadcast.
• LiFi system uses modulation schemes such as OOK, VPPM, CSK.
• The PHY and MAC layers of LiFi system are defined in 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 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 do not pass through walls. Moreover it has limited range and works in Line of Sight (LOS) mode which adds extra layer of privacy to the data being transmitted.
➨LiFi uses visible light spectrum that does not cause any EM (Electro-Magnetic) interference.
➨It reduces RF congestion by using 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 limited range and requires clear LOS for its operation.
➨LiFi signals can be blocked easily by physical obstacles such as walls, furnitures or even human bodies. This poses challenge in offering un-interrupted connectivity in complex environments.
➨LiFi based internet system requires installation of LED lighting infrastructure and compatible receiver devices. Hence the initial setup costs may be higher compared to traditional wifi infrastructure.
➨LiFi system can be affected by external light sources such as sunlight and other bright light fixtures.
➨LiFi compatible devices and its adoption is limited compared to already established WiFi technology.

What is WiFi Technology ?

As mentioned WiFi full form is Wireless Fidelity which 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 Wi-Fi network, wireless routers emit radio waves within specific frequency bands. The devices equipped with wifi adapters or SoCs can detect and connect to these networks enabling wireless communication and internet acccess. The router is connected to the internet via wired connection (e.g. DSL, fiber or cable modem) and acts as gateway between internet and connected devices.

Following are the features of WiFi technology as depicted in the figure-2.
• It consists of two important devices namely, a Wi-FI router or Access point(AP), Wi-Fi dongle and Wi-Fi stations.
• As shown a WiFi AP or Router is connected to the internet using a broadband cable or with cellular network. All the wifi compatible mobile phones, tablets or laptops are connected with AP (or router) to obtain internet.
• WiFi network operates in either of two modes viz. adhoc (i.e. BSS-Basic Service Set) and infrastructure (i.e. ESS-Extended Service Set).
• In BSS WLAN compliant stations (i.e. STAs) communicate directly. In ESS WLAN compliant STAs communicate with APs (Access Points) to access internet.
• WiFi supports different speeds and coverage ranges as per implemented standard in the devices (STAs, APs). 802.11a supports upto 54 Mbps, 11b upto 11 Mbps, 11n supports 72 Mbps/150 Mbps as per BW (20MHz/40MHz), 802.11ac wave-1 supports upto 1.3 Gbps (80MHz, 3 streams, 256QAM), 802.11ac wave-2 supports upto 3.5 Gbps (160MHz, 4 streams, 256QAM) etc. The distance coverage of 70 meters (indoor) to 250 meters (outdoor) can be achieved.
• WiFi network operates in different frequency bands viz. 2.4 GHz, 5 GHz.
• The PHY and MAC layers of WiFi system 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, IoT devices are equipped with wifi capabilities and hence it ensures broad compatibility and ease of use.
➨WiFi networks can support multiple devices simultaneously.
➨WiFi networks can easily be upgraded to accommodate mote 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 wifi repeater or additing extra router.
➨Modern wifi standards (802.11ac and 802.11ax) offers higher data transfer rates but it can not be matched with speeds delivered by LiFi.
➨WiFi devices consume more power which potentially impact battery life of mobile devices.
➨Some studies raised concerns regarding potential health effects of RF radiation from wifi devices, although the evidence is inconclusive.

Let us compare LiFi vs WiFi and understand difference between LiFi and WiFi technologies with respect to various features and their respective advantages and disadvantages.

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

Conclusion : In summary, the purpose of LiFi is to utilize visible light for high-speed, secure, and localized wireless data transmission where as WiFi offers widespread wireless connectivity using radio waves for broader coverage and device compatibility. Each technology serves different use cases and complements each other in meeting diverse wireless communication needs.

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