Visible Light Communicatoin: Transfer data using light

Abstract

There are many types of communication channels like wired and wireless (infrared, microwave) to send the data from source to destination, but none of the existing technology is considered as the best way of communication as there are plethora of adverse effects of it. For example, if there are four different companies operating in the same building and they are using different services of wireless from different ISPs, say it, first is using 100Mbps plan, the second one is using 200Mbps and in the same way other remaining users. Here the only hurdle is that as everyone is receiving different speed, there are lots of chances of blending of signals. So to overcome such difficulties we can have VLC.

The new research that is carried out by the scientists all over the world is to transmit the bits of data trough the rays emitting from LED bulbs generally used in our houses. This technology is known as visible light communication, which states that the light we see everyday can be used to transmit the text, videos, pictures and many more. To accomplish this goal, photosensors are used where one sensor acts as a sender and the other as a receiver. Just have photosensor at either side of the device (tablet, laptop … etc) and start sending the stream of bits at a speed of 1GB/s which can be accomplished from only fiber optic cables nowadays which Google is offering in Kansas city.

Introduction

There are many data hungry applications and the radio spectrum is limited. The use of wireless mobile applications is growing and we are running out of radio spectrum to use. Researches around the world are fine-tuning technologies that use the standard lightning equipment to cheaply transmit high-speed data streams wirelessly, even the equipment appears to be producing nothing more than normal illumination. Generally, the technologies rapidly and subtly fluctuate the intensity of Light Emitting Diode (LEDs) in a way that is imperceptible to the human eye.

Need of VLC

The idea of using light to send information to send information, a field known as Visible Light Communication, has been around for well over a century. In fact, Alexander Graham Bell sent a wireless phone message in 1880 using his invention known as the Photophone.

But academic and commercial interest in visible light communication has accelerated in recent years. The increasing popularity of LED lights, which can be more finely controlled than traditional incandescent bulbs, makes light-based technology more practical and economical. Also, the exponentially growing demand of wireless communication devices has taxed radio spectrum, resulting in a need to find alternatives.

The light intensity of LEDs can be controlled very rapidly and are faster than the human eye can detect. Digital information can easily be converted by a small device in the light fitting into minute variations in light, even at very low levels of light and transfer to other devices many times faster than the data coming into building. The light emissions are harmless to humans and can be transmitted even if the light source is dimmed or reflected around the room.

Who Founded It?

Herald Hass, a professor at the University of Edinburgh who began his research in the field in 2004 showed how a table lamp with an LED bulb to transmit a video of blooming flowers that was then projected onto a screen behind him without using any antenna.

Achievement

Thankfully, data transmission speeds have come a long way since the days of dial-up when the users would have plenty of time to twiddle their thumbs as they waited for an image or MP3 to make its way to their hard drive. These days, broadband cable currently supports speeds of around 30 megabits per second, which a hell of an improvement. Now researchers have outdone that by a factor of around 85,000 by using twisted beams of light to transmit data at up to 2.56 terabits per second.

Twisting beams means modifying 8 beams of light so each one modified or twisted in a DNA-like helical shape as it propagated in free space. With each beam having its own twist can be encoded with “1” and “0” data bits, they formed 8 independent data streams.

Specially designed electronic devices generally containing a photodiode receive signals from such light sources, although in some cases a cell phone camera or a digital camera will be sufficient. The image sensor used in these devices is in fact an array of photodiodes (pixels) and in some applications its use may be preferred over a single photodiode.

Conclusion

Light-based data transmission technology is attractive because it allows wireless communication without the use of radio gear, which can be dangerous in places like oil platforms (where it can cause sparks) and underwater (where the salt conducts electricity), or on planes (where it can interfere with other radio equipment). In addition transmissions can be stopped simply by blocking the light, and thus can be stopped by walls, so there is less risk of data leaking out of the house or office. VLC can be used as a communication medium for ubiquitous computing, because light-producing devices (such as indoor/outdoor lamps, TVs, traffic signs, commercial displays, car headlights/taillights, etc) are used everywhere.