up -and -c oming li -fi technology under visible light c ... · up -and -c oming li -fi technology...

Up-and-Coming Li-Fi technology under Visible Light Communication

To transfer the data among multiple users in train

B.Anitha Vijayalakshmi 1, K. Ramkumar

2, A.Aruna3

1Assosiate Professor, Department of Electronics & Communication Engineering

Kings Engineering College

2Professor, Department of Computer Science and Engineering


3Assistant Professor, Department of Electronics & Communication Engineering


Abstract:

One of the essential demands in today‟s lives is sharing of information. With the continually

increasing traffic demand the accessible radio frequency (RF) spectrum with available frequency

was not able to support multiple users in delivering broad band and multimedia content. Wireless

fidelity (Wi-Fi) is great for general wireless exposure in less dense area, whereas light fidelity

(Li-Fi) is ideal for high density wireless data coverage in cramped area and for recreating radio

frequency interference issues. In onboard rail networks the delivering of smooth Wi-Fi access is

critical. The fifth generation (5G) visible light communication (VLC) technology includes

hundreds of terahertz of license free bandwidth, and uses the visible light spectrum in providing

high data rate and security. Li-Fi holds a great scope in future due to its outstanding speed. This

paper focuses on the smart way of data transfer to multiple users in train using Li-Fi technology

under VLC.

Key words: Multiple users, Li-Fi, Train, VLC

I. Introduction

The RF based wireless communication has been holdup due to the spectrum scarcity in RF

spectra. The practice of visible light spectrum is at a halt, intact in condition for communication.

The VLC harmonizes the RF-based mobile communication systems for underhanded high-

International Journal of Pure and Applied MathematicsVolume 119 No. 16 2018, 1587-1598ISSN: 1314-3395 (on-line version)url: http://www.acadpubl.eu/hub/Special Issue http://www.acadpubl.eu/hub/

1587

capacity mobile data networks. The attention towards VLC using the wavelength of 380–780 nm

is due to its enormous communication bandwidth, unregulated spectrum, high data rate services,

and license-free predominantly. Obvious visible light signals don't infiltrate through the vast

majority of the surfaces in the earth so that it offers inborn remote correspondence security. In

where a VLC framework is conveyed, data might be contained inside the restricted space of the

particular premises. This for all intents and purposes takes out the possibility of casual

eavesdropping.

Customary fluorescent and incandescent light sources can be quickly supplanted by light

emitting diode (LED) because of its vitality efficiency and longer lifetime with the end goal of

brightening. The utilization of LEDs in VLC creates scope for communication together with

illumination. A LED as a transmitter and a photodiode (PD) as a detector can be comprehend in

VLC system. Coherent modulation/detection techniques are not possible in VLC due to the

incoherent emission of the LED. Therefore, intensity modulation with direct detection techniques

has to be used to encode data. In LEDs, data is modulated into the intensity of the light source

and transmission takes place across an optical wireless channel.

To ensure the passengers with real time multimedia information, access to social networks in

station or in train and to meet the traffic demand it‟s required to put in place the broadband

telecommunication networks, using a variety of technologies whether fixed or wireless [2].

Heterogeneity of networks like Wi-Fi, GSM-R, Satellite, 3G / 4G networks is becoming a real

headache for train operators and infrastructure managers [2]. The VLC technology combines

communication in addition to illumination and also affords security, intelligent lighting, indoor

localization and much more. In the future prospects of 5G wireless access networks the VLC

technology will show its greater impact due to its inherent advantages.

II. Issues with RF technology

a) Capacity: Wireless information is transmitted through radio waves which has constrained

transfer speed and costly.

b) Efficiency: There are 1.4 million cell radio base stations that expend monstrous measure of

vitality. In this way productivity of such base stations is just 5%.

International Journal of Pure and Applied Mathematics Special Issue

1588

c) Availability: It isn't prudent to utilize cell phones in aeroplanes and at places like

petrochemical plants and oil pumps.

d) Security: Radio waves can penetrate through walls. They can be intercepted. If someone has

knowledge and bad intentions, they may misuse it [2].

The need to utilize visible light as medium depends on: Low usage cost – by basic establishment

methodology and installation of LEDs. Low support cost – by low power utilization and long

life-time of LEDs.

III. Visible light communication

The part of the VLC spectrum which is visible to the human eye is the visible light spectrum.

The band width of this range connects to 430-770 THz. Imagine that how a flash light can be

used to send the mores code. If the flash` light is made on and off very quickly according to the

binary data of user requirement we get a system wherein there is communication plus

illumination. The availability of the large bandwidth in VLC resolves the low bandwidth

problem in RF communication as illustrated in Fig. 1. The VLC receiver only receives signals if

they reside in the same room as the transmitter, therefore the receivers outside the room of the

VLC source will not be able to collect the signals and thus, it has the protection from security

issues that happens in the RF communication systems.

.

Fig.1 Visible light spectrum

As an obvious light source can be utilized both for illumination and communication, in this

manner, it spares the further power that is required in RF communication. Keeping in perception


1589

the above advantages, VLC is one of the confident competitors on account of its highlights of

non-licensed channels, high bandwidth and low power consumption.

A. Feasibility of VLC technology

Global Positioning System (GPS) is a famous positioning system nowadays. In fact, the visible

light communication system could be installed into the street lamps. The blind spots problem in

GPS could be tackled. Also, the errors in detecting the actual position could be reduced. LED

commercial displays can be seen everywhere. The displays could be used as the wireless

communication transmitters [3]. As there is a rapid growth in population, the increase in the

number of devices accessing the wireless internet, the airwaves becoming increasingly clogged,

making it more and more difficult to get a reliable and high-speed data transmission. Li-Fi may

solve the above issues and overcome the shortage of radio frequency bandwidth and also allow

internet to be used in the places where traditional radio based wireless communication isn‟t

allowed such as aircraft or hospitals [4].

In Wi-Fi reduction in speed and the jamming take place which is today‟s problem as the number

of users are increasing and also waves create a harmful effect for living things. This jamming

problem get reduces to a great extent by using Li-Fi and such that we can precede towards the

cleaner, greener, safer and brighter future without radio wave. Li-Fi using LED‟s can be

encouraged to produce a safe and green technology. Li-Fi will bring out Li-Fi products for firms

installing LED-lighting systems. In future, data for laptops, Smartphone‟s, and tablets can be

transmitted through the light in a room by using Li-Fi [5].

Fig. 2: Li-Fi module


1590

LEDs switches speedily to “ON” and “OFF such that human eye cannot recognize the operating

speed of LEDs and thereby causing the light source to appear to be constantly ON. This

undetectable ON-OFF activity allows data transmission via binary codes. Switching ON an LED

is binary „1‟, switching it OFF is binary „0‟. It is conceivable to encode information in light by

fluctuating the rate at which LEDs flicker ON and OFF to give different strings of 1s and 0s.

Modulation is rapid to the point that people can't see it. A light sensitive device (photo detector)

then collects the signal and converts it again to original data.

B. Li-Fi technology

Li-Fi is a high hustle bi-directional completely connected, visible light wireless communication

system and is equivalent to Wi-Fi, which uses radio frequency for communication. The Wi-Fi

signals have the issue of interference with other RF signals. The objective of Li-Fi Consortium

is to encourage the Development and dissemination of optical remote advancements, navigation,

natural user interfaces and others. There are around 14 billion lights around the world, they

simply should be supplanted with LED ones that transmit information," says Haas. "We figure

VLC is a factor of ten times less expensive than Wi-Fi." Since it utilizes light rather than radio-

frequency signals, VLC could be utilized securely in Aircraft, combined into medical devices

and hospitals where Wi-Fi is prohibited, or even underwater, where Wi-Fi doesn't work by any

means. Li-Fi innovation utilizes a piece of the electromagnetic range that is as yet not

extraordinarily expended. The Visible Light Spectrum is in actuality particularly a part of our

lives for many years and does not have any real sick impact. Besides there is 10,000 times more

space accessible in this range and simply incorporating on the bulbs being used, it likewise

increases to 10,000 times greater accessibility as a framework, all inclusive.

IV. General purpose illumination with LED technology

The VLC technology‟s vital source is LED. Universally useful enlightenment for home, open

spots and enterprises request white or amber lighting. By and by, lighting organizations are

occupied with growing high power white LED bunches for such applications by accomplishing

comparable light yield as incandescent or fluorescent lamps while reducing power wastage. In

the years that took after, high brightness white LEDs were formed by mixing of high power blue

LED with yellow phosphors, white phosphor LEDs have recently reached luminous efficacies of


1591

150 lm/W. White Light from (R/G/B) LEDs directly mixes light in required proportions from

three i.e., red, green and blue (RGB) LEDs to produce white light of desired chromaticity. The

luminous efficacy of this “RGB” solution is very high, with about 29 lm/W.

The LEDs can create the white light illumination in two ways, the blue emitters with phosphor

layer and red–green–blue–amble (RGBA) emitters. The phosphor-based LEDs has enhanced

data rate, higher bandwidth than RGB LEDs. Recently, data rates in excess of 1 Gbps has been

reported using off-the-shelf phosphor-coated white LEDs and 3.4 Gbps has been demonstrated

with an off-the-shelf red-green-blue (RGB) LED. Another similar Gigabit/s wireless system with

phosphor-coated white LEDs has been demonstrated using a 4×4 multiple-input-multiple-output

(MIMO) configuration [6]. LED encourages with unmatched energy proficiency and life

expectancy. The acknowledgment of LEDs practice will be of steady in ascend in future because

of its conservative frame factor, diminished utilization of unsafe materials in outline and lower

warm age in long stretch of unremitting use.

Fig.3 LEDs installed in train

The LEDs are equipped in changing to various light intensity levels imperceptible by a human

eye at a very fast rate when comparable with older illumination technologies. The data will be

encoded in the emitting light and the photo detector referred as light sensor, receives the

modulated signals and decodes the data. This implies the LEDs can give out both the double

purpose of illumination and communication.


1592

V. Problem in employing Wi-Fi on onboard rail networks

In onboard rail networks the delivering of smooth Wi-Fi access is critical. Onboard environments

are inclined to vibrations, have constrained space and it requires altered wireless devices to

ensure system stability. The wireless devices used in onboard must make sure that each traveler

has dispensed adequate transfer speed and gave secured arrange access, without being on edge

about being hacked.

Fig.4 Problem of hacking

Most of the passengers in high-density trains, anticipate that web access is to read messages or

watch online recordings. The onboard network designers must think about the sort of utilizations

that travelers are habituated to practice over the web. So that they may eliminate the possibility

of the train‟s passengers troubled by unstable internet access. To ensure the safety in onboard

systems from hackers connected to the same network topology, the public network environments

must be protected and the privacy of passengers must be preserved for those who access the

train‟s Wi-Fi access point (AP)s.

Fig.5 Unstable connectivity in dense environment


1593

VI. System implementation:

In onboard train, the recommended block is shown in Fig. 3 [7] to provide effective data

transmission from the base station to receiving station.

Fig.5 Recommended block

The system has a Li-Fi RF driver to sense the signal from the base station using the medium of

light and the photo detector in the device captures the signal and passes the information to the

passengers. „1‟ is transmitted if the LED is on; if it‟s off the transmitted output is „0‟. LEDs can

be toggled on and off very quickly, such that it offers pleasant opportunities for transmitting

data. Li-Fi can‟t replace conventional radios altogether, but it could enhance the development of

wireless data transmission inside the train in terms of speed and make it easier to throw a

wireless signal to the multiple users without interruption.

Fig.6 Transmitter module


1594

Transmitter section consists of PC where the data input is given. The given input is encrypted by

Manchester coding. The encrypted data is stored in the low power microcontroller. The stored

data in the microcontroller is then fed to the Li-Fi module which consists of driver circuit and

LED. By varying the current given to the LED the optical output also varies at high speed. Thus

the binary data from PC is given to Li-Fi module where electrical signal is converted into light

signal.

Fig.7 Receiver module

Then the light signal is received into the receiver side which consists of photo detector. It

converts light signal to electrical signal. Then the binary data from photo detector is given in to

PC where the decryption is done. Thus the user can view the original form of files. The figure 8

shows the uninterrupted communication that can be supplied by Li-Fi under the avoidance of

problem of hacking.

Fig.8 Li-Fi supports uninterrupted communication

The figure 9 shows Li-Fi module for data transmission. In our work video file transmission at a

rate of 9.6 kbps has been achieved at a distance of 50 cm. The work has been carried out in

indoors.


1595

Fig.9 Li-Fi module for data transmission

VII. Conclusion

Visible light communication using Li-Fi technology will be the best solution in the future for

better illumination and communication inside trains using LED luminaire for lighting system.

The concept of Li-Fi is now inviting a great deal of interest. It offers a genuine and very efficient

substitute to radio-based wireless. Li-Fi is the optical wireless communication for data, audio and

video streaming in LEDs, this type of new invention can be stimulated to produce a safe and

green technology. Li-Fi is still in its incipient stages and thus offers tremendous scope for future

research and innovation.

Reference

1. “Next Generation of Railways and Metros Wireless Communication Systems”, Alain

Bertout, Senior Solution Architect, Alcatel-Lucent , Eric Bernard, Business Development

Director, Alcatel-Lucent

2. Pushpendra Verma, Dr. Jayant Shekhar, Preety and Dr. Amit Asthana ,.“LIGHT-

FIDELITY(LI-FI): TRANSMISSION OF DATA THROUGH LIGHT OF FUTURE


1596

TECHNOLOGY”, International Journal of Computer Science and Mobile Computing,

Vol.4 Issue.9, September- 2015.

3. Sylvester C.S., “VISIBLE LIGHT COMMUNICATIONS“, International Journal of

Advanced Computational Engineering and Networking, ISSN: 2320-2106, Volume-4,

Issue-10, Oct.-2016.

4. NIKSHEP. K N and SOWMYA. G, “VOICE AND DATA COMMUNICATION USING

Li-Fi”, International Journal of Advanced Computational Engineering and Networking,

Volume-4, Issue-10, Oct.-2016.

5. Mr. Shailendra Yadav, Mr. Pradeep Mishra, Miss. Minakshee Velapure, &

Prof.P.S.Togrikar, “LI-FI Technology for Data Transmission through LED”, Imperial

Journal of Interdisciplinary Research (IJIR) Vol-2, Issue-6, 2016.

6. Azhar, A., Tran, T., and O‟Brien, D., “A Gigabit/s Indoor Wireless Transmission Using

MIMO-OFDM Visible-Light Communications,” IEEE Photonics Technology Letters 25,

171–174 (Jan.15 2013)

7. B. Anitha Vijayalakshmi and M. Nesa Sudha, “Illumination and Communication Using

LED as Light Source in Underground Mines”, Springer Nature Singapore Pte Ltd. 2018

8. Mohammad Soliman, Paul Unterhuber, Damini Gera,” First Analysis of Inside Train

Communication with ITS-G5 Measurement Data”, IEEE, 2016


1597

up -and -c oming li -fi technology under visible light c ... · up -and -c oming li -fi technology...

Documents