i3 - July/August 2016 - 24

CISCO FORECASTS 30.6 EXABYTES PER
MONTH OF MOBILE DATA TRAFFIC BY 2020.

(Source: Cisco VNI Mobile, 2016)

Our smartphones, tablets, PCs, printers and smart
TVs must compete for limited bandwidth. And with
the emergence of more "Internet of Things" such as
refrigerators, watches, and fitness bands comes greater
congestion. By 2025, as a result of the continued
proliferation of wireless data traffic the radio frequency
(RF) spectrum which extends from 30 kHz to 300
GHz will not be sufficient to cope with demand.
We're not yelling "wolf " here. Noting that "spectrum
is the oxygen of innovation," CTA supports FCC efforts
to conduct voluntary incentive auctions in order to
obtain 500 MHz of new radio spectrum for wireless
broadband internet services. And, indeed, the FCC
recently reached its initial 126 MHz target after broadcast stations made commitments to participate in
the unprecedented auction of airwaves. This will give
auction bidders a chance to compete for what has been
described as "low-band 'beachfront' spectrum."
But as FCC Chairman Tom Wheeler put it "this
auction truly is a once-in-a-lifetime opportunity" and
the need for additional spectrum to meet growing
customer demand, as we usher in the age of 5G, will
remain an ongoing issue well after the conclusion of
the spectrum auction process now underway if we are
to have robust wireless broadband capability.

Other Options on the Table
Fortunately, technology may provide help. Visible Light
Communications (VLC), commonly known as Li-Fi,
is a wireless optical networking technology that uses
light-emitting diodes (LEDs) for data transmission.
It promises to deliver high-speed, bi-directional, networked mobile communications in a manner similar
to Wi-Fi but using visible light rather than the scarce
and cluttered RF spectrum. Li-Fi is being viewed as an
alternative to traditional RF-based communications and
can complement, but not replace RF communications.
Li-Fi works because LEDs used in light bulbs are
semiconductor devices. By affixing a microchip the
electric current sent through them to produce light
can be switched on and off at extremely fast speeds,
somewhat akin to a high-tech Morse code. As with all
digital devices the ability to turn on and off rapidly
creating different strings of "0's" and "1's" provides a
24

JULY/AUGUST 2016

LiFi-X
by
Pure Lifi

Jugnu
by
Velmenni

THERE
WILL BE

5.5
GLOBAL
MOBILE USERS,
UP FROM

4.8
IN 2015.

means to encode data streams. Standard LED light
bulbs are controlled by a driver that turns the LED on
and off, or dims and brightens it. With Li-Fi enabled
LED light bulbs, the driver is used to transmit
encoded data by controlling the LED light.
The modulation methods employed to bring this
about are similar to those used in low-cost infra-red
communications devices such as television remote
control units. But while Infra-red communication is
limited in power due to eye safety requirements, LED
light bulbs have high intensities and can thus achieve
large data rates. The modulated light can be detected
by a photo-detector device and converted back to an
electrical signal. Digital-to-analog converters within the
unit modulate the LED very rapidly -the Li-Fi modulation frequency starts at 1 MHz so the flickering of the
LED is imperceptible to the human eye.
In effect, Li-Fi can turn an LED lamp into a
wiretless access point similar to a Wi-Fi router,
providing web access and high speed data transmission in addition to illumination. Indeed, Li-Fi
is well suited to fill both functions as most indoor
environments are illuminated and studies show that
a substantial portion - more than 70 percent of wireless traffic - originates indoors.
The technology was unveiled in 2011 by Professor
Harald Haas of the University of Edinburgh who
coined the term Li-Fi during a TED Global talk. Haas
said that since the visible light spectrum is 1,000
times larger than the entire 300 GHz of radio, microwave and mm wave radio spectrum, there is a big
untapped reservoir of resources for wireless communications. Visible light spectrum also is not regulated
by government mandate so it can be used freely for
communications purposes.

A Few Disadvantages
What's not to like? Well, a few things, but none
appear to be deal breakers. By using radio waves
Wi-Fi can pass through walls and ceilings. Light
cannot, so Li-Fi must be line of sight and cannot pass
through walls from room to room. Consequently, to
enjoy connectivity in each room of your home, Li-Fi
capable LED bulbs will need to be placed throughout the house. The coverage of each LED lamp is
expected to be up to 10 m2 and so the theory suggests
that when you leave that space, you would be illuminated by another lamp, handover takes place, and you
would not lose your wireless connection.
The fact that Li-Fi cannot pass through walls
makes the data stream inherently more secure; users
(and would-be hackers) must be physically in the
space in order to access the data. This also greatly
reduces the possibility for casual eavesdropping.
I T I S I N N O VAT I O N

Courtesy of PRNewsFoto/pureLiFi; Courtesy of Velmenni

EXABYTES
PER
MONTH

http://purelifi.com/ http://velmenni.com

i3 - July/August 2016

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