VISIBLE LIGHT COMMUNICATION
Visible light communication (VLC) is the one that employs transfer of visible light between the wavelengths of 400 and 800 THz (780–375 nm). A subset of optical wireless communications technology is VLC.
The system employs conventional fluorescent bulbs (not special communications equipment) to carry signals at 10 kbit/s across short distances, or LEDs for up to 500 Mbit/s. Over distances of 1–2 kilometres (0.6–1.2 mi), systems like RONJA may transmit at full Ethernet speed (10 Mbit/s).
Because light-producing equipment (such as indoor/outdoor lamps, TVs, traffic signs, commercial displays, and car headlights/taillights) are utilised everywhere, VLC can be employed as a communications channel for ubiquitous computing.
Light modulation is essential in order to transfer data. The form in which the light signal fluctuates in order to represent different symbols is known as modulation. In order to decrypt the information. Unlike radio transmission, VLC modulation necessitates the modulation of the light signal around a positive dc value, which is responsible for the lamp’s lighting. As a result, the modulation will be an alternate signal around the positive dc level, with a high enough frequency to be undetectable to the naked eye.
There are various modulation strategies to choose from, which fall into three categories: Single-Carrier Modulated Transmission (SCMT) and Multi-Carrier Modulated Transmission (MCMT) are two types of modulated transmission (MCMT) and Pulse-Based Transmission (PBT).
- Human safety
- High data rate
- Unlicensed spectrum
The VLC has various applications in
- Military Communication
- Vehicle-to-vehicle Communication
LED can be used for lighting the homes but also as means for wireless in house communication.
VLC has created a revolution in the consumer networking areas because of efficiency and affordability. It is promising technology even if it is still in a very early stage.