Surf internet, stream videos and make calls simply from a torch or the street lights or the headlights of your car. When Prof Harald Haas gave his first talk about this concept at TED, I was both fascinated and amused after watching it. But, honestly, I could never see that happening in the very near future. Blame my short-sighted vision or appreciate Prof Hass’s blazing fast progress, the first product is ready and out there in the world. It’s called Li-1st. Before telling you more about the product, let me talk about the science behind the concept.
LiFi is a term coined by Prof Harold, in line with conventional term WiFi. Both LiFi and WiFi are effectively used in communicating data using the electromagnetic waves, with the only difference that WiFi uses Radio Frequency while LiFi uses the visible light spectrum. If you compare the two spectrums, Visible light spectrum is almost 10,000 times broader than Radio frequency, meaning greater data transfer capacity. The basic idea of binary data in digital communication is still intact, however, instead of transmitting 1’s and 0’s, we switch the LED bulbs on and off in extremely small time gaps [almost 1000th of a nano second].The protocol used is more or less 802.11 [same as WiFi], with Manchester encoding followed with on off keying and pulse position modulation, in the physical layer of the protocol. The bottleneck of line of sight communication is both boon and bane. Opaque objects will definitely jam the LiFi communication, however, the protocols can be designed robustly using the concept of Orthogonal frequency division multiplexing [OFDM]. With this type of modulation, we can rather benefit from multi-path and direct communication is no more a necessity. Also, the fact that this type of communication is more suited to short-range communication, makes it lesser prone to being hacked. A small chipset with protocol implemented and connect to a light source is all that it takes to get this set up ready. It’s low-cost and capable of 250 times faster data rates than the best broadband currently available through WiFi.
Let’s talk about the first LiFi product. The father of LiFi, Prof Hass, founded the company PureLiFi [earlier known as PureVLC], which focuses specifically on visible light communication. Their first product is a bidirectional visible light communication device which is capable of uplink and downlink speed of 5 Mbps. There are two parts in the set up; first part is a transceiver unit which is connected to an LED light source and the other part is a similar transceiver connected to another light source and also connected to the laptop though USB. You can use this set up with the two light sources separated over a range of 3m for the above mentioned data rate. The light sources can be dimmed down without affecting the quality of video streaming much, so that the flash is not a disturbing factor. The product is still in the prototype phase and has also been demonstrated at a few conferences.
The applications of this concept are restricted only by the limits of our imagination. Imagine the reading lights on your top in the airplanes being a source of internet. Imagine the headlights in your cars being a source for navigation information, traffic control and accident prevention. Imagine beaming torches at one another to communicate.
LiFi is not supposed to replace WiFi by any means. Long distance communication is still made easy only through wireless networks, generally with RF and Microwaves. However, LiFi is simply an efficient add on to the existing infrastructure of illuminating sources around us.