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Difference between radio waves and light waves | WiFi vs LiFi

This page compares radio frequency waves and light waves and mentions difference between radio waves and light waves. Wifi is based on radio signal waves (EM waves) where as Lifi is based on light signals.

Introduction:
Electromagnetic spectrum is divided into eight portions based on radiation intensity and their wavelengths. There are major two divisions viz. radio frequency (RF) spectrum and optical spectrum. Radio spectrum includes radio waves, microwaves and terahertz (THz). Optical spectrum includes infrared, visible waves, ultra violet, X-rays and gamma radiations.

Electromagnetic or radio spectrum

What are radio frequency waves ?

These are EM signals which occupy 3 KHz to 300 GHz. Radio frequency waves are at much lower frequencies compare to microwave frequencies. The radio waves transmitted by antenna use wavelengths of about 1 mm to 100 meters. They are used for various applications such as cellular communication, radio and TV broadcasting, satellite communication, WLAN (i.e. wifi), Zigbee and so on.

The unit of radio frequency signal is in Hertz (Hz). It is number of oscillations or cycles per second. The equation below is the relationship of its wavelength and frequency.
Wavelength (λ) = C/Frequency
Where, C is 3 x 108 meters/second

Light vs radio frequency Spectrum

Following is the typical system used for radio transmission and reception.

wireless

The transmitter part and receiver part consists of following components. Before radio frequency waves are transmitted by antenna, they go through modulation, up conversion and power amplification as per different system requirements.

rf transceiver

Similarly, radio waves are processed after it is received at the receiver by antenna. They go through various modules such as LNA, down conversion and demodulation.

What are light waves ?

These are EM waves which occupy 430 THz to 790 THz frequency range. The light waves occupy wavelengths from 380 nm to 750 nm.

Li-Fi internet architecture

LEDs, lasers or fluorescent bulbs are used as transmitter of light waves where as photodiode detectors are used as receivers. Refer LiFi tutorial >> for more information.

Data bits are modulated by light waves before transmission.

Difference between radio waves and light waves

Following points summarize major difference between radio frequency waves and light waves.
➨Radio waves are affected by other EM sources where as light waves are not affected.
➨Radio waves consume more power where as light waves consume less power.
➨Radio waves offer low bandwidth where as light waves offer high bandwidth.
➨Radio waves do not require line of sight between transmitter and receiver where as light waves require it.
➨Radio waves are harmful where as light waves are not.
➨Radio waves are amplified before transmission where as light waves are not amplified.
➨Radio waves cover medium to larger distances where as Light waves cover shorter distances.
➨Radio waves are not visible where as light waves are visible.

Difference between wifi and lifi

The Following table summarizes the major comparison between wifi and lifi technologies based on various specifications.

WiFi vs LiFi, Difference between WiFi and LiFi

Refer LiFi vs WiFi >> for more difference between lifi and wifi technologies which are based on radio frequency waves and light waves respectively.



LiFi and WiFi Related Links

LiFi tutorial
LiFi vs WiFi
LiFi vs GiFi
Data Over Light basics mentioning how Li-Fi works
WiFi Internet using WiFi hotspots
MiFi vs WiFi
WiFi RF Channels


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