100 Gigabits per second could be blasted by Laser Li-Fi

 In Internet, Network


Are you having problems with blotchy Wi-Fi? Well, the answer to this may be Li-Fi. The technology uses LED-based room lighting instead of radio waves to transmit data. But one of the leading Li-Fi proponents is already looking much beyond LEDs to laser-based lighting, which he says could bring a tenfold increase in data rates.

“The problem is that LEDs, although they are more energy efficient than incandescent light, they still can be improved in terms of their light output,” says Harald Haas, chair of mobile communications at the University of Edinburgh and a member of the Ultra-Parallel Visible Light Communications Project. “We strongly believe the next wave of energy efficient lighting will be based on laser diodes.”

Li-Fi encrypts the data coming on the light from LEDs by adjusting their output. The rapid flickering is not visible to the human eye; however, a receiver on a desktop computer or mobile device can read the signal, and even send one back to a transceiver on the ceiling of a room resulting in a two-way communication. But several of the LEDs use a phosphor coating to convert blue light to white. This in turn limits the speed with which the devices can be adjusted, thereby holding down the data rates.

A research published in Optics Express, Haas and his team exhibited that replacement of the LEDs with off-the-shelf laser diodes vastly improved the situation. Lasers, with their high energy and optical efficiency, can be adjusted at 10 times the rate of LEDs. On the other hand by using phosphors, laser lighting would create white light by mixing the output of several lasers operating at different wavelengths. This means that each wavelength can be used as a separate data channel, the same sort of wavelength division multiplexing that lets optical telecommunications carry so much data. The Edinburgh group’s experiment used nine laser diodes.

While LED-based Li-Fi could reach data rates of 10 Gb/s, which is an improvement over the 7 Gb/s maximum of Wi-Fi; however, using lasers could enhance that speed to “easily beyond 100 Gb/s,” Haas says.

Mr. Haas is a person who introduced this concept in TED talks.

Currently to go ahead with such a setup would be costly, but Haas believes that mass production will lower cost of the lasers and move them into lighting applications. BMW is already selling cars with laser-based headlights on its i8 model. “That is only the start of a technology move as laser diodes get more inexpensive,” Haas says.

This OWC (Optical Wireless Communication) technology uses light from light-emitting diodes (LEDs) as a medium to deliver networked, mobile, high-speed communication in a similar manner as Wi-Fi. Li-Fi could lead to the Internet of Things, which is everything electronic being connected to the internet, with the LED lights on the electronics being used as Li-Fi internet access points. The Li-Fi market is projected to have a compound annual growth rate of 82% from 2013 to 2018 and to be worth over $6 billion per year by 2018.

Visible light communications (VLC) works by switching bulbs on and off within nanoseconds, which is too quickly to be noticed by the human eye. Although Li-Fi bulbs would have to be kept on to transmit data, the bulbs could be dimmed to the point that they were not visible to humans and yet still functional. The light waves cannot penetrate walls which makes a much shorter range, though more secure from hacking, relative to Wi-Fi. Direct line of sight isn’t necessary for Li-Fi to transmit a signal; light reflected off the walls can achieve 70 Mbit/s.

Li-Fi has the advantage of being useful in electromagnetic sensitive areas such as in aircraft cabins, hospitals and nuclear power plants without causing electromagnetic interference. Both Wi-Fi and Li-Fi transmit data over the electromagnetic spectrum, but whereas Wi-Fi utilises radio waves, Li-Fi uses visible light. While the US Federal Communications Commission has warned of a potential spectrum crisis because Wi-Fi is close to full capacity, Li-Fi has almost no limitations on capacity. The visible light spectrum is 10,000 times larger than the entire radio frequency spectrum. Researchers have reached data rates of over 10 Gbit/s, which is more than 250 times faster than superfast broadband.[14][15] Li-Fi is expected to be ten times cheaper than Wi-Fi. Short range, low reliability and high installation costs are the potential downsides.

PureLiFi demonstrated the first commercially available Li-Fi system, the Li-1st, at the 2014 Mobile World Congress in Barcelona.



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