UPSC Prelims 2020 Important topics: Visible Light Communication (VLC) technology

Visible light communication (VLC) is a wireless method that enables high-speed transmission of data with visible light. This data is transmitted by modulating the intensity of light given off by a light source. The signal is received by a photodiode device that transforms the data into forms that are readable and readily-consumed by end users.

Visible light communication (VLC) is a wireless method that enables high-speed transmission of data with visible light. This data is transmitted by modulating the intensity of light given off by a LEDs. The signal is received by a photodiode device that transforms the data into forms that are readable and readily-consumed by end users. Its biggest advantage is the size of the entire visible light spectrum, 380 to 700 nanometers. The nature of light is that it is unable to pass through opaque surfaces, therefore it is a short-range transmission. 

Transmission speed is VLC’s another advantage as light travels 186,000 miles per second, which is way faster than the 344 meters per second travelled by radio waves in air. A larger bandwidth and faster speed allow it to transmit large amounts of data at much higher speed compared to Bluetooth technology.  The Radio Frequency (RF) communication suffers from interference while Visible Light Communication (VLC) has high bandwidth and is immune to interference from electromagnetic sources. 

In the discussion of light, this usually means the entire electromagnetic spectrum, which comprises everything from gamma rays to radio waves. Only a small portion of the entire electromagnetic spectrum can be seen by the human eye, which is aptly called visible light.

The use of visible light in the transmission of data holds many different key advantages over technologies that make use of radio frequency. Its biggest advantage is the size of the entire visible light spectrum, which is 10,000 times larger than the entire radio spectrum, which is also too congested due to its overuse. With mobile traffic expected to increase sevenfold by the year 2021, the vast size of the visible light spectrum, which carries 300 THz of license-free bandwidth carried on visible wavelengths, certainly makes VLC a viable option.

Aside from the size of the visible light spectrum, light travels 186,000 miles per second, which is way faster than the 344 meters per second traveled by radio waves in air. This means that communication using light is virtually instantaneous, which also makes VLC the fastest means of communication among those commercially available in the market.

Data is transmitted in VLC systems by modulating light. At slow speeds, this will be seen as a constant flickering of light, which breaks down data into a system of ones and zeroes that will be converted into consumable data through a transceiver. However, the speed of data transmission is highly dependent on the speed of the flickering. For this reason, light emitting diodes (LED) are used as the primary light source in VLC systems. LED bulbs are semiconductors, giving them the ability to handle ultra-fast modulation of light occurring at speeds undetectable by the human eye.

There are some characteristics that are unique to VLC. These characteristics include:

Signal confinement

The nature of light is that it is unable to pass through opaque walls. This makes it easy to confine signals to within a single room, which increases the level of security of the network.

Non-line-of-sight

Many believe that because VLC systems use light, any blockage can severely hinder its ability to transmit data. That is definitely not the case as it is not dependent on line of sight. In fact, studies have shown that they can still perform in rooms that are severely obstructed.

Safe in hazardous environments

VLC can be used as a practical alternative for areas where RF signals are perceived as a hazard. Aside from using non-RF technology to deliver data, the light source used in these systems emit low energies, ensuring their safe use. These “hazardous” environments include hospitals, airplanes, or mines.

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