LiFi – Visible Light Communications

My Note: This gives a good layman's explanation of the article reposted here on April 7th, 

Terahertz speed 3Gbps LiFi network with LED bulbs

http://terahertztechnology.blogspot.com/2013/04/terahertz-speed-3gbps-lifi-network-with.html

by Ashit Sood 

Heard about WiFi but what is this LiFi? Confused? Yes we are here to solve your confusion.

German researchers have successfully transmitted data at 3Gbps using conventional LED bulb. In practicality, the same system is capable of transmitting 500Mbps. The concept of visible light communications (VLC) also referred as LiFi has received a lot of attention in recent years, mostly due to the growing prevalence of� LED lighting. Unlike incandescent and fluorescent bulbs, LEDs are solid-state electronics, meaning they can be controlled in much the same way as any other electronic component, and switched at a high speed using techniques like Pulse Width Modulation (PWM). VLC is essentially WiFi – but using terahertz radiation (light) instead of microwaves (WiFi). Instead of oscillating a WiFi transmitter, VLC oscillates an LED bulb – and of course, on the receiving end there’s a photo detector instead of an antenna.

The rumours say that apart from the above mentioned data rate, the range will be four meter that is nearly 13 feet and with the trade-off with data rate the range can be increased i.e. 120Mbps over 20 meters (67 feet). Rather than actually using a standard LED bulb, VLC system is a black box, with an LED and photo detector on the front, and an Ethernet jack on the back to connect it to the rest of the network. In this system, the hardware only allowed for 30MHz of bandwidth to be used, limiting the total throughput. To reach 3Gbps, researchers have found a way of squeezing 180MHz of bandwidth out of the LEDs — and instead of using just one LED they now use three different colors.

Advantages

• LiFi can turn any LED lamp into a network connection.
• LiFi operates at high frequencies (hundreds of terahertz).
• LiFi can be used in areas where there’s extensive RF noise.
• VLC improves privacy, because your signal can be easily obscured from prying eyes with opaque materials.

— Ashit Sood

He is a hardworking and punctual student. Believes in sharing knowledge with others and loves to keep a watch of everything happening around him, may it be technology, political, economic, etc.