1. 1. PREFACE
Light Fidelity (Li-Fi) is a technology that promises to give a seamless access to the internet at an
ultra-high speed. It is a technology of the future, which will make the access to the internet easier
like never before, all you need to do is to sit beneath alight source.
Li-Fi is unique as the same light energy used for illumination may also be used for
communication. It opens up a spectrum of connectivity that is 1000 times greater than Wi-Fi where
Radio Frequency technologies are running out of spectrum.
Li-Fi uses LED's and photo detectors for data transmission which makes it cheaper than current RF
technologies and also provides better speed. It also ensures better security than currently popular Wi-Fi
as light cannot pass through walls so no data can be accessed from outside.
The technology has ability to overtake current data transmission technologies in near future. More
and more loT devices will be able to connect to each other and underwater communication will
also be easier than it was never before with RF technology.
2. INTRODUCTION
In simple terms, Li-Fi can be thought of as a light-based Wi-Fi. That is, it uses light instead of radio
waves to transmit information. And instead of Wi-Fi modems, Li-Fi would use transceiver-fitted LED
lamps that can light a room as well as transmit and receive information. Since simple light bulbs are
used, there can technically be any number of access points.
This technology uses a part of the electromagnetic spectrum that is still not greatly utilized- The Visible
Light Spectrum. Light is in fact very much part of our lives for millions and millions of years and does
not have any major ill effect. Moreover there is 10,000 times more space available in this spectrum and
just counting on the bulbs in use, it also multiplies to 10,000 times more availability as an
infrastructure, globally.
It is possible to encode data in the light by varying the rate at which the LED's flicker on and off to
give different strings of Is and Os. The LED intensity is modulated so rapidly that human eyes cannot
notice, so the output appears constant.
2. 3. ARCHITECTURE
The Li-Fi architecture contains various devices such as LED bulbs, mobile devices and the photo
detector which receives the binary data over light. The binary data is captured by few light receptors
which are installed on all types of connecting devices such as computer tablets, phones, televisions, or
appliances.
Fig 2.1 Architecture Of Li-Fi Technology
The various components of a basic Li-Fi system are as follows
a. Server
A server is a computer program that provides services to other computer programs (and their users) in
the same or other computers. The computer that a server program runs in is also frequently referred to
as a server. That machine may be a dedicated server or used for other purposes as well.
3. b. Internet
The Internet, sometimes called simply "the Net", is a worldwide system of computer networks – a
network of networks in which users at any one computer can, if they have permission, get information
from any other computer (and sometimes talk directly to users at other computers).
c. Lamp Driver
Lamp Driver is a small integrated circuit designed to supply the current required by a lamp. It manages
the incoming voltage and current to the voltage and current level requirements of the lamp.
d. Lead Lamp
A high brightness white LED acts as a communication source. It is guided by the PCB and powered by
PA and is enclosed in an aluminum enclosure. An LED lamp is a light-emitting diode (LED) product
which is assembled into a lamp (or light bulb) for use in lighting fixtures LED lamps have a lifespan
and electrical efficiency which are several times greater than incandescent lamps and are significantly
more efficient than most fluorescent lamps.
e. Design of The Bulb
The first part is the Ethernet Cable Slot. This is the slot where the LAN cable will be connected to
connect the Bulb with the Internet.
The second part is the Real Time Clock and Battery Pack. The function of a clock is mainly to generate
pulse, and so is the function of the Real Time Clock in the Bulb. It generates pulses as per the
requirement of the data.
The third and the most important part is the Micro controller & Circuit. The Micro controller part
controls all the functionalities of the Bulb. Its main functions are to control the clock timing, in control
which data is to be sent andto whom it is to be sent, and to control the intensity of light.
4. 4. HOW Li-Fi WORKS?
The working of Li-Fi is based on a very simple concept, when the LED is on, a digital I is transmitted,
and when it is off, a digital O is transmitted. The LED's can be switched on and off very quickly, which
gives nice opportunities for transmitting data.
The Li-Fi technology is based on the Visible Light Communication which uses the visible light for data
communication. In VLC, we use a source of illumination which can not only produce illumination but
also send information using the same light. So we can say that VLC is illumination along with
communication.
Li-Fi is a fast and cheap optical version of Wi-FI, the technology of which is based on Visible Light
Communication (VLC). VLC is a data communication medium, which uses visible light between 400
THz (780 nm) and 800 THz (375 nm) as optical carrier for data transmission and illumination. I use
fast pulses of light to transmit information wirelessly.
5. 5. APPLICATIONS
The dramatic growth in the use of LED's (Light Emitting Diodes) for lighting provides the
opportunity to incorporate Li-Fi technology into a plethora of LED environments.
Li-Fi is particularly suitable for many popular internet "content consumption" applications such as
video and audio downloads, live streaming, etc. These applications place heavy demands on the down
link bandwidth, hut require minimal up link capacity. In this way, the majority of the internet traffic is
off- loaded from existing RF channels, thus also extending cellular and Wi-Fi capacities.
There are many applications for Li-Fi.
These include:
a. RF Spectrum Relief
Excess capacity demands of cellular networks can be off-loaded to Li-Fi networks where available.
This is especially effective on the down link where bottlenecks tend to occur.
b. Smart Lighting
Any private or public lighting including street lamps can be used to provide Li- Fi hot-spots and the
same communications and sensor infrastructure can be used to monitor and control lighting and data.
6. c. Mobile Connectivity
Laptops, smart phones, tablets and other mobile devices can interconnect directly using Li-Fi. Short
range links give very high data rates and also provides security.
Fig 8.2 Mobile Connectivity Using Cellular Wi-Fi and Li-Fi networks
d. Hazardous Environments
Li-Fi provides a safe alternative to electromagnetic interference from radio frequency Communications
in environments such as mines and petrochemical plants
e. Hospital & Healthcare
Li-Fi emits no electromagnetic interference and so does not interference with medical instruments, nor
is it interfered with by MRI scanners
7. 6. Advantages and disadvantages of LI-FI:
A. Advantages of LI-FI :
a. Quicker Data Transmission than Wi-Fi –
An essential selling purpose of Li-Fi innovation is that it has a quicker information transmission rate
than Wi-Fi. Noticeable light range has a transmission capacity that is multiple times bigger than whole
radio recurrence and microwave range. Analysts at the University of Oxford have asserted that they
effectively tried a trial Li-Fi application with a bi-directional speed of 224 gigabits for each second.
Observe that most Wi-Fi networks send information at around 20 megabits for each second and move
rates are subject to distance and obstructions. This bit of leeway is the motivation behind why defenders
have bets on Li-Fi as an answer for settling that issues including the transmission capacity impediments
of Wi-Fi and the developing measure of information created and devoured by clients.
b. Simple and Inexpensive to Deploy –
Recall that the current operational ideas and trial utilizations of Li-Fi innovation focus on the utilization
of LED lights. This implies that a Li-Fi organization can be incorporated effectively with existing LED
lighting frameworks. Basically, any place there is a light source, there can be admittance to the Internet.
It is additionally worth referencing that LED lights are reasonable to deliver and their market cost is
moderately moderate. Investigators foresee that Li-Fi organization would be multiple times less
expensive than Wi-Fi. They are likewise more energy productive than radiant lights and fluorescent
lights. Albeit a Li-Fi-empowered LED light should stay went on to continue sending information, it
tends to be diminished to underneath human perceivability and save energy cost while as yet emanating
enough light to function as an organization switch.
c. Security Due to the Limitations of Light –
Another remarkable advantage or preferred position of Li-Fi is that it is safer than Wi-Fi. Remote
correspondence innovations dependent on radio recurrence and microwaves are more helpless against
snoopping, signal capturing or unapproved interference, beast power assaults, and spontaneous
organization associations. Recollect that light waves can’t enter through dividers and entryways. They
additionally have a more limited reach. Equivalent is valid for infrared light and bright radiation. The
signs transmitted by a Li-Fi item and information it communicates stay limited to a shut territory, for
example, a room or lobby. Admittance to organization is restricted. This implies that Li-Fi innovation
offers an additional layer of security than Wi-Fi.
d. Safe From Electromagnetic Interferences –
Moreover, Li-Fi additionally has a bit of leeway of being insusceptible from electromagnetic
impedances that influence radio-based remote correspondence advancements. The innovation is
likewise helpful in territories that are electromagnetic delicate, for example, airplane lodges, clinics, and
atomic force plants, among others since it doesn’t cause electromagnetic obstructions. Note that some
clinical instruments utilized in clinics, just as the radar and correspondence frameworks in an airplane
are delicate to radio recurrence.
e. Sweeping Future Applications –
The advancement of additional availability is another bit of leeway of Li-Fi innovation. The way that it
offers quicker information move rates implies that it can propel the mainstream sending of the Internet
of Things or IoT which require huge information and compelling and effective network.
8. B. DISADVANTAGES OF LI-FI:
a. Restricted Range and Connectivity –
The impediments of the noticeable light furnish Li-Fi with a security advantage over Wi-Fi. Be that as it
may, these constraints likewise make burdens. Actual boundaries, for example, dividers and entryways
limit operational extent of a Li-Fi-empowered LED light. Recall that information communicated by a
Li-Fi item stays bound to a nearby dispersed on grounds that light can’t infiltrate misty articles and has a
more limited reach. In foundations, for example, house or building, empowered LED lights should be
deliberately positioned in rooms, corridors, and different segments to extend extent of the Li-Fi network.
A solitary Wi-Fi switch has more extensive and longer reach than a Li-Fi switch. These impediments of
Li-Fi likewise make it not ideal for use in open Wi-Fi networks.
b. Inaccessibility of Compatible Technologies –
It will take a long time for Li-Fi to turn out to be more reasonable than Wi-Fi. Current gadgets, for
example, PCs, cell phones, and tablet PCs actually use equipment for Wi-Fi organizing. These gadgets
would not promptly work with a Li-Fi network since they don’t have the essential equipment details. Li-
Fi isn’t promptly in reverse viable. It is additionally worth referencing that the quicker information
move pace of this innovation stays irrelevant or unimportant until Internet speed from specialist
organizations improves. In territories or nations that are infamous for having more slow Internet speeds
than their partners, conveying a Li-Fi organization would be inane. Thus, it will take coordination from
different businesses and areas to advance mass selection of this innovation.
c. Light Interference and Light Pollution –
Different burdens of Li-Fi are powerlessness to light obstruction and advancement of light
contamination. Observe that despite fact that this innovation is invulnerable to electromagnetic
impedances, different wellsprings of light may meddle with sign. Daylight can meddle with light signals
created by a Li-Fi-empowered LED light. The relating recipient may struggle handling these signs. Web
interference is conceivable. Besides, on grounds that empowered LED lights should stay on, they can
offer further to light contamination, particularly whenever set at higher splendor to make up for
conceivable impedance with other light sources.
d. Conceivable Cost Implications –
Sending Li-Fi is hypothetically reasonable due to the little expense related with creation of LED lights.
In any case, establishment cost can be more costly than Wi-Fi sending due to innovation is generally
new and the interest stays low and concentrated experts are as yet not many. The way that a solitary
home requirements a few Li-Fi switches to grow extent of the organization and accessibility of Internet
availability could likewise mean extra buy and establishment costs. Observe that a solitary Wi-Fi switch
is sufficient for a normal measured house.
10. 8. Conclusion:
The Li-Fi technology is now developed into a ubiquitous system technology with innovative networking
capabilities for universal application to provide a variety of device platforms for high-speed internet
communications.
This study showed that Li-Fi technology is an appropriate alternative to Wi-Fi technology. Although Li-
Fi technology does not use any radio frequencies, but it provides safer, greener and cheaper technology.
This LI-Fi technology provides users with better security measures, capacity and availability as
compared to Wi-Fi. The future implications of Li-Fi include its application in different fields such as
industries, medicine, education and other regions requiring further exploration.
