visible light communication in intelligent transportation...

Visible Light Communication in Intelligent Transportation

Systems Navin Kumar, PhD

Sr. Member IEEE, IAENG(HK), IETE, IE(India)

Amrita University, Bangalore

Navinkumar@ieee.org

Monday, May 12, 2014

http://icc2014.ieee-icc.org/2014/private/programTutorials.html

Amrita Vishwa Vidyapeetham Bengaluru Campus

Outline

2 Monday, May 12, 2014 Navin

Introduction Intelligent Transportation Systems

Advantages/Applications

Intelligent vehicles and Infrastructure

Vehicular Communication

Overall System Architecture Advantages and Applications

Visible Light Communications

ITS Strategic Plan and Opportunities

Technical Details and Prototype Experiments and Results Research Opportunities Conclusions

Introduction: WHAT IS ITS?

Intelligent transportation system (ITS) refers to efforts to add information and communications technology to transport infrastructure and vehicles, in order to:

– improve safety

– reduce vehicle wear,

– reduce transportation times, and

– reduce fuel consumption.

DEFINITION …

ITS improves transportation safety and mobility and enhances productivity through the use of advanced communications technologies.

ITS apply well-established technologies of communications, control, electronics and computer hardware & software to the surface transportation system.

Monday, May 12, 2014 5 Monday, May 12, 2014

Identified Benefits

Time Savings

Improved Throughput

Reduced Crashes and Fatalities

Cost effectiveness

Increased Customer Satisfaction

Energy and Environmental Benefits

Problems Caused by Congestion and Options

Problems:

Increased…

– Travel time

– Travel cost

– Air pollution

– Accident risk Options: Construct new roads

Covered in geometric design Not likely to happen on a large scale

Reduce Traffic Travel demand management Alternative transportation

Increase existing infrastructure capacity Uses intelligent transportation systems (ITS) Monday, May 12, 2014 7

Construction is Part

of the Solution

But will be VERY expensive and politically painful. Because where it is needed most is in the heart of metropolitan areas. Monday, May 12, 2014 8

Option 2: Alternative Transport

New rail capacity or aother medium which would avoid the congested highways, will be just as difficult and expensive to build as new highways.

New Rail Capacity.

SkyTran: Personal

MagLev Transporter

Option 3: Increase Existing Infrastructure Capacity

An alternative to expensive new highway construction is the implementation of strategies that promote more efficient utilization of transportation infrastructures.

These strategies are known as the Intelligent Transportation Systems (ITS).

This aims to: reduce travel time, ease delay and congestion, improve safety, and reduce pollutant emissions

Intelligent transportation systems

ITS, encompass a broad range of wireless and wireline communications-based:

– information,

– control and

– electronics technologies.

When integrated into the transportation system infrastructure, and in vehicles themselves, these technologies help:

monitor and manage traffic flow, reduce congestion, provide alternate routes to travelers, enhance productivity, and save lives, saves time and money.

Applications Overview Global Positioning Systems Weather information systems Bus Information System Traffic and transit management Real-time information Parking Incident management Emergency management Electronic toll collection Commercial vehicle operations

12 Monday, May 12, 2014

Five Primary Functional Areas of ITS

Advanced Traffic Management Systems (ATMS)

Advanced Traveler Information Systems (ATIS)

Commercial Vehicle Operations (CVO)

Advanced Public Transportation Systems (APTS)

Advanced Vehicle Control Systems (AVCS)

Application: Bus Information System

• Public Transport Information

– Countdown: Real-time Bus Stop Information

Application: Real-Time Information

Automobile traffic

Public transport

Parking

Airport arrivals/departures

News, banking, stocks…

Information on -availability Guidance to: - Available facility - Actual spot

Incident Management

Commodity Classification Automated Tracking System (CCATS)

Camera and Computer-Aided Incident Detection (CCIDS)

CCATS & CCIDS: Video-Based Solutions for Data Collection and Incident Detection

Monday, May 12, 2014 15 Navin Kumar

Application: Incident Management

Road Safety and ITS Road Crashes[WHO’08]:

– the second leading cause of death among young people aged 5 to 29

– the third leading cause of death among people aged 30 to 44 years

– Over 1.2 million people are killed annually

Traffic Congestion: – affects the day-to-day life of citizens

– has a great impact on business and economic activities

These issues therefore generate less income, affecting the sustainable growth of cities throughout the world

ITS have drawn a lot of attention to solve various traffic problems

The area of ITS is directly related to human and material safety

Application scenario: IntelligentVehicles & Infrastructure

Driver Assistance Systems

Collision Avoidance Systems

Collision Notification Systems

Electronic payment and pricing

Emergency management

Transit Management

Freeway Management

18 Navin Kumar Monday, May 12, 2014

Application scenario: Intelligent Infrastructure

Road Weather Management

Roadway Operation and Maintenance

Information Management Traveler

information Crash Prevention

and Safety

Commercial Vehicle operation

Intelligent Transportation System

ITS & Vehicular Communication (VC) Technology

Inside car – Bluetooth, Zigbee

Car to car – VANET,802.11p (5.85-5.925 GHz)

Car to road – 802.11p

Car to Internet – 3G, WiMAX

(current) CALM (Continuous Air-interface, Long and Medium range )

VC Service Scenario

Sensor

Access Point

Car to Car

Car to Road

Home Network

Roadside Assistance

Service Provider

Sensor

InternetRadioAccess

Network

WLAN, WiMAX,

GSM, GPRS,3G & B3G

Sensor

PresenceeCall

Context–AwareService

Provisioning

VC Service Integration

IMSCore

Network

Home Network

Access

Network

PoCPresence

eCall IPTV

Context–AwareService

Provisioning

Internet

Advanced Traffic Management Systems

Photo from the Human-Computer Interaction Lab: University of Maryland Monday, May 12, 2014 24 Monday, May 12, 2014

WSDOT Traffic Systems Management Center

Advanced Traveler Information Systems

Advanced Public Transportation Systems

Advanced Vehicle Control Systems

Intelligent

Cruise Control (ICC)

System

ITS Strategic Plan – Research Questions & Framework

ALL MUST BE ANSWERED TO BE DEPLOYABLE

5% What policies/governance/funding are required for sustainability? How to address public concerns for privacy and ensure that applications do not cause driver distraction?

Is technology stable, reliable, secure, and interoperable?

Are international standards available to ensure interoperability?

Are applications available and benefits validated? What is the minimum infrastructure needed for the greatest

benefit? How much, where, when and what type?

What is the degree of market penetration required for effectiveness?

Our Task In our town or city – what are our

transport objectives – what do we want our transport system to achieve and how do we want it to improve?

From what we’ve seen so far – how could ITS help us to achieve our objectives? … and now on to how Visible Light Communication (VLC) as one of the technologies can be used in ITS…

What is VLC?

31 http://icc2014.ieee-icc.org/2014/private/programTutorials.html

Introduction

Visible Light Communication ?

1 0 0 1

Communication using visible light Wirelessly.

Light Emitting Source (one component)

Light Detector (one component)

Monday, May 12, 2014 Navin

Introduction: History

• Smoke signals of the ancient tribes

• The use of fire or lamp Beacon fire, lighthouse, ship-to-ship comm.

33 5/12/2014

Information delivery using mirror reflection (Heliograph): is a wireless solar telegraph that signals using Morse code flashes of sunlight reflected by a mirror.

Traffic Signal

Traffic light : R/G/B color multiplexing (Walk/Stop)

Introduction: History …

Alexander Grahm Bell’s Photophone (1880) Optical source: sunlight Modulation: vibrating mirror Receiver: parabolic mirror Distance: 700 ft (213m)

Source: http://www.freespaceoptic.com/

In 1920, somewhat by accident, Losev foresaw the usage of optical links to relay information.

In 1969, Gfeller presented “Wireless In-House Data Communication via Diffuse Infrared Radiation”. It became the stepping stone to VLC.

Facts, Figures, and Trends of Wireless Networks and Technology

Several Technologies move in the same direction

4G Many Access

Networks

Introduction

Introduction • Wireless data transmission via optical carriers:

opportunity, many yet unexplored.

Optical Wireless Communication (OWC): Significant technical and operational advantages.

OWC, in some applications: a powerful alternative to radio frequency (RF) and,

complementary to existing RF wireless systems.

Frequency Spectrum

1024 1022 1020 1018 1016 1014 1012 1010 108 106 104 102 100 ν(Hz)

λ(m)10-16 10-14 10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

Increasing Frequency(ν)

Increasing Wavelength(λ)

380nm 780nm

γ rays X rays UVMicrowaveIR FM AM

Radiowave

Longwave

Visible Spectrum

Licensing Area/ISMSpecial purposed Area

Non-Licensing Area

1024 1022 1020 1018 1016 1014 1012 1010 108 106 104 102 100 ν(Hz)

λ(m)10-16 10-14 10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

380nm 780nm

Radiowave

Longwave

Visible Spectrum

Non-Licensing Area

Low Frequency (High wavelength)

Large Coverage Mobility

High Frequency (Small wavelength)

High Bandwidth Security

IrDA : 334THz(900nm) to 353THz (850nm) Monday, May 12, 2014

Introduction … • Variations of OWC can be employed in a

diverse range of communication applications:

outdoor inter-building links (on the order of kilometres)

very short-range (on the order of millimetres) optical interconnects within integrated circuits

Optical Wireless Communication and Systems

• Usually, OWC includes:

J. M. Kahn, and. J. R. Barry, "Wireless infrared communications," Proc. of the IEEE, pp. 265-298, 1997.

1. Infrared (IR): for short range [Kahn & Barry,

1997], - approximately 1 to 400THz frequency band,

(Much of the energy from the Sun arrives on Earth in the form of infrared radiation).

OWC – Infrared …

Used for -night vision equipment when there is insufficient visible light to see.

• Infrared imaging (capturing invisible infrared images and making them visible)

• as heating source

• IR data transmission in short-range communication

• These devices usually conform to standards published by IrDA, (Infrared Data Association).

• Remote controls, etc.

41 Monday, May 12, 2014

OWC – Free Space Optics

- A technology that can be installed license-free worldwide, - can be installed in less than a day. -Offers optical fiber like bandwidth and data speed - Normally so called, Wide band Home Access or --Last Mile Access Network

This line-of-sight technology approach uses invisible beams (193.5GHz and 382.2GHz: 1550 nm, 785 nm) of light to provide optical bandwidth connections.

2. Free-Space Optics communication: for longer range

FSO: Applications

Fig.: A Simple Point-to-point FSO Connection

Fig.: FSO Corporate Networks

FSO: Applications

44 Monday, May 12, 2014

FSO: System Requirement and Design Issues

Tracking

• The requirements for tracking systems in carrier-class free-space optics systems.

Scintillation and atmospheric effects Scintillation effects and techniques for mitigating the detrimental effects of scintillation.

Power Control and Eyesafety The benefits of power control for long-term laser reliability and eyesafety

FSO: System Requirement and Design Issues

Fig.: Atmospheric Issues

FSO: System Requirement and Design Issues ….

• Ex.: Attenuation because of Fog/Snow storm

Taken from - Scott Bloom, The Physics of Free-space optics, white paper AirFiber Inc.

FSO: Overall Functional Blocks

Transmitter Laser, Lens, Driver

Receiver

Photo Detector Front End Amplifier

Tracking

Microprocessor based tracking/alignment system

Fig.: Overall FSO Block Diagram

BASIC COMPONENTS: OPTICAL WIRELESS

Transmitter

Optics

Array of sources can also be used

Source

LED or Laser diode -Eye safety regulation means that high power required sources to be modified -Three ranges:

# Visible (used for both illumination and data transmission) # Near infrared

700nm>Wavelength<1400nm- Low cost Wavelength>1400nm- Eye safe

OWC – Basic Components …

Receiver consists of:

Photo Detector

- Optical power to photo current

Input radiation

Photodetector (or array of detectors)

Optical filter

Supported by: Optical filter

Rejects ‘out-of-band’ ambient illumination noise

Concentrator

Amplifier and following processing

Concentrator or Lens Collection of radiation

Preamplifier (or number of preamplifiers) normally Transimpedance Amp. and signal processing

OWC Configuration

Non LoS

BASIC CONFIGURATION: LoS or DIFFUSE

Configuration Characteristics

Diffuse -Multipaths from Transmitter to Receiver Robust to blocking

o Large coverage

- Path loss More - Subject to multipath dispersion

LoS - Single path from Transmitter to Receiver

No dispersion Path loss Less

o Very high bandwidth available

Difficult to provide coverage

OWC Characteristics

MERITS - Very High Bandwidth

o 200THz carrier frequency

-Secure (LoS) -Cost Effective -Interference

o Suitable for RF sensitive

environments

-Potential for low power

Problems and possible Solutions - Noise from ambient light

o Optical filtering o Electrical filtering in receiver

- Less sensitive than radio - Link Blocking

o Geometrical solutions o Diffuse channels o Combine with RF

- Available components optimised for fibre-optic applications

o Higher performance available if optimised for OW

Development

Optimal Integration into 4G Infrastructures

Emerging Area Visible Light Communication

VLC… VLC is a novel kind of Optical Wireless which uses

license-free visible light spectrum (380nm-780nm) to carry information wirelessly.

Monday, May 12, 2014 55

1024 1022 1020 1018 1016 1014 1012 1010 108 106 104 102 100 ν(Hz)

λ(m)10-16 10-14 10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

380nm 780nm

Radiowave

Longwave

Visible Spectrum

Non-Licensing Area

1024 1022 1020 1018 1016 1014 1012 1010 108 106 104 102 100 ν(Hz)

λ(m)10-16 10-14 10-12 10-10 10-8 10-6 10-4 10-2 100 102 104 106 108

380nm 780nm

Radiowave

Longwave

Visible Spectrum

Non-Licensing Area

VLC …

Monday, May 12, 2014 56

The emitter is normally LED source which has inherent characteristics of high speed switching and therefore, technology performs DUAL FUNCTIONs of Lighting and Data Communication simultaneously.

It is a cost effective technology, no interference to RF and widely suitable as supplementary technique to the most popular RF systems.

VLC offers short/medium range data communication

VLC: Advantages VLC System has many advantages especially derived from advancement in

light emitting diodes (LEDs) technology.

– Cost effective (can be designed on existing infrastructure)

– Energy efficient system (LED usage can save over 60% energy)

– Long life (LEDs technology usage)

– Unlicensed and unregulated spectrum (free in life is the best)

– Theoretically Unlimited bandwidth (limited to electronics devices)

– Harmless to human (unlike Infrared)

– Uses at restricted places (unlike RF-EMI) such as Hospital, aeroplane

– Parallel and Directive communication ( use of colour and directive LEDs)

– Highly Secure (LOS – what you see is what transmit)

– Considered a Green Technology (less CO2 emission – use of LEDs)

– Ubiquitous characteristics (where light can reach, data comm is possible)

– and many more……….

57 Monday, May 12, 2014

Visible Light Communication (VLC)

That is, Communications of information using light (visible to the human eyes).

VLC offers short/medium range data communication

Visible Light Communication is a Novel kind of Optical Wireless Communication which uses visible light (400THz to 790THz) from Light Emitting Diodes (LEDs) as a medium for data communication.

5/12/2014 59

VLC Motivation

Intrinsic Characteristic of VLC •Visibility •No interference /No regulation

Environmental trend •Energy saving •Green Technology

Communication Community trend •Ubiquitous (Connected anywhere, anytime) •Security

LED Advancement •LED technical evolution (efficiency, brightness) •LED illumination infrastructure

Advancement in LEDs Technology.

VLC Motivation …

LEDs as brighter as our conventional lights (Fluorescent or Incadescent lamp)

-Switching speed.

-Illumination characterisitics

Mostly in terms of:

Inherent characteristic (Semiconductor Device).

VLC Motivation – LED Illumination

2 7 1020

200lm/WLuminous Efficacy

VLC Motivation –LED Advancement

Therefore, Visible Light emitted from LED can be modulated to send information data i.e. Simultaneous operation of Lighting and Switching.

VLC Motivation…

Free Spectrum (Best things in life are free )

At the same time, LEDs can switch at high rate (over 10 MHz) [as such they are Semiconductor devices]

VLC Motivation – LED Applications

Illumination moving from incandescent/ fluorescent to solid state sources (LEDs) - Predicted to become predominant method for room illumination - Used extensively in traffic systems (traffic signals, rear light cluster) - Headlight is being also used - Extra wireless capacity available at (potentially) low cost

5/12/2014 65

LED- The VLC Source

Single chip LED spectrum

Red Green Blue -Higher cost -Higher bandwidth -For WDM -Modulation without colour shift

Blue LED & Phosphor -Low cost -Phosphor limits bandwidth -Modulation can cause colour shift

General Characteristics:

Ubiquitous: Omni-presence.

Harmless for human body and electronic devices.

Available visible light bandwidth is about 300THz. It is considerably larger than the current available radio frequency bandwidth (about 300GHz)

Achievable at Low Cost and on Existing Infrastructure or with slight modification

VLC Characteristics

Ambient interference:

Obstacles: Must obtain a Line-of-Sight (LoS).

Interferences from other visible light sources (sun, bulbs…)

Also suffer from the multi-path effect as light reflects.

VLC Characteristics

5/12/2014 68

VLC Characteristics: Relative Advantages and Disadvantages with Radio and Infrared (IR)

Communication

Parameters Radio Infrared VLC

Bandwidth Around 300GHz Few 100 THz 300 THz

Data Rate Few 100 Mbps Few 10 Mbps Dependent on distance and limited by LED switching speed

Spectrum Regulation Licensed Regulated & Licensed Not licensed

Safety Issue Susceptible to the biological damages to humans by the electromagnetic wave.

Eye safety problem No danger to eyes or biological effect. Easily used with medical instruments or even on airplane.

Usage Everywhere with cell phones and the wireless LAN, etc

Notebook, Cell Phone, PC etc.

Getting popularity

Suitability Wide applications and popularity. Restricted in Hospital and airplane

Short range (mostly indoor) Short & Medium, both indoor and outdoor

Implementation and cost Complex, Costly Easier, cost effective Cost effective, Used on existing infrastructure or with slight modification

Security Many complex algorithm needed May be secured (very short distance)

Secured (What you see is what you transmit)

Complex and Challenging

VLC Can be a supplementary and not replacement to Radio

RF or Optical Link?

VLC Applications

INDOOR

VLC Applications …

71 Monday, May 12, 2014

VLC Applications: Indoor

LiFi Configuration

72 Monday, May 12, 2014

VLC Applications: Indoor …

Music Broadcast Parallel Transmission (Taken

from Nakagawa Lab, Japan)

73 Monday, May 12, 2014

VLC Applications: Outdoor UNDERWATER

74 Monday, May 12, 2014

VLC Applications: Outdoor …

75 Monday, May 12, 2014

INTELLIGENT TRANSPORTATION SYSTEMS (ITS)

VLC Applications: Outdoor …

30mLED Lights

A scenario of VLC in ITS Ubiquitous Communication with Road Illumination

The project VIDAS (VIsible light communication for advanced Driver Assistance Systems) discusses one of the use cases of the emerging technology, VLC and the THESIS is in the framework of the project. 76

VLC Applications: Outdoor - ITS

What’s behind the bend?

Integration of VLC with ITS

77 Monday, May 12, 2014

VLC Applications: ITS-Road Safety

VLC as Advanced Driver Assistance System: pls clk to

78 Monday, May 12, 2014

Overall Architecture

VLC System

79 Monday, May 12, 2014

Block Diagram: Conceptual Design

80 Monday, May 12, 2014

Emitter Characteristics and Model:

LED (Lambertian Model):

VLC Modelling

where θ is the viewing angle and E0(d) is the irradiance (W/m^2), also given in luminous flux (lm) on the axis at a distance d from the LED.

Fig.: Lambertian Emitter Source

Field Programmable Gate Array & Hardware Implementation

PN Code

Sequence Corr. Pk

Partial Corr. Pk

Observations

Novel Designed

+1+1+1-1-1 -1+1-1-1+1

-DC Balanced -Low resources -Easy Implementation -PG = 10dB

Barker +1+1+1-1-1-1+1-1-1+1-1

-Nearly DC Bal. -High Resource -Complex -PG = 10.4dB

PN Code

Input Data

MicroBlaze

IPLBILMB

DLMB INTR

INTC UART

PLBClock

IRQ Lines

50 MHzMB

PLBLMB

DataBuffer

+Frame

Processing

Binary

DSSS EMITTER CORE

AWGN(channel SNR

simulation)

Bipolar to

Unipolar

Output to Optoelectronics

Processing

ClockManager

Unipolar to Bipolar

Output Data

MicroBlaze

IPLB ILMB

DLMBINTR

INTCUART

PLB Clock

IRQ Lines

50 MHzMBPLBLMB

DSSS RECEIVER CORE

Input from Optoelectronics

Matched Filter

PN Code

Treshold Detector

PER Bipolar to Unipolar

EMITTER ARCHITECTURE RECEIVER ARCHITECTURE

Conceptual Design ....

Layer Architecture and ITS Integration ..

Under Review –(1) Navin K., Luis A. Nero and Rui L. Aguiar, “VLC Layer Architecture for ITS”, IEEE ITS Magazine

(2) Navin K., Luis A. Nero and Rui L. Aguiar,” Employing Traffic Lights as Road Side Unit for Road Safety Information Broadcast”, Book Chapter

Emitter Model and Design

Optimized Placement Multilane Traffic Light System set-up

(1) Navin Kumar, Luis Nero Alves and Rui L. Aguiar, “Design and Analysis of the Basic Parameters for Traffic Information

Transmission using VLC”, Proc. IEEE Intl. Conf., Wireless Vitae’09, May 17-20, 2009 .

(2) Navin K., Nuno R., Luis A Nero and Rui L. Aguiar, “Analysis and Design of LED-based Traffic Light Emitter Model for Road Safety Application”, Elsevier Journal Transportation Research Part C. – Under Review

200mm dia TL, 240 LEDs, 1200mcd

Modulation Analysis

OOK Multilevel PPM Inverted PPM Sub Carrier PPM DSSS SIK - Interference cancellation - Avoid Jamming - Tolerance of Noise - Very High Data Rate is not important

DSSS SIK Operation

(1) Navin K., Luis A. Nero and Rui L. Aguiar, “Performance Study of Direct Sequence Spread Spectrum based VLC Systems for Traffic Information Transmission,” – Under reivew (IEEE Transaction on VTS)

FPGA & Hardware Implementation

PN Code

Input Data

MicroBlaze

IPLBILMB

DLMB INTR

INTC UART

PLBClock

IRQ Lines

50 MHzMB

PLBLMB

DataBuffer

+Frame

Processing

Binary

DSSS EMITTER CORE

AWGN(channel SNR

simulation)

Bipolar to

Unipolar

Output to Optoelectronics

Processing

ClockManager

Unipolar to Bipolar

Output Data

MicroBlaze

IPLB ILMB

DLMBINTR

INTCUART

PLB Clock

IRQ Lines

50 MHzMBPLBLMB

DSSS RECEIVER CORE

Input from Optoelectronics

Matched Filter

PN Code

Treshold Detector

PER Bipolar to Unipolar

PN Code

Sequence Corr. Pk

Partial Corr. Pk

Observations

Novel Designed

+1+1+1-1-1 -1+1-1-1+1

-DC Balanced -Low resources -Easy Implementation -PG = 10dB

Barker +1+1+1-1-1-1+1-1-1+1-1

-Nearly DC Bal. -High Resource -Complex -PG = 10.4dB

EMITTER ARCHITECTURE RECEIVER ARCHITECTURE

VLC Prototype

VLC Receiver

OPTOELECTRONICS & FPGA

Receiver

FPGA Rx

FPGA Tx

OPTOELECTRONICS AND FPGA DEVELOPMENT

VLC Prototype Experiment in Lab

(1) Domingos Terra, Navin Kumar, Nuno Lourenço, Luis Nero Alves, and Rui L. Aguiar,” Design, Development and Performance Analysis of DSSS-based Transceiver for VLC”, IEEE EUROCON, Lisbon, Apr. 2011

Experiment Scenario (Lab Environment)

Distance Tx –Rx (2.5m) Height (0.85m) -Lights ON -Lights OFF

Experiment Scenario Outdoor/Daylight

Bright Sky, Directly Under Sun at Noon time – Detector facing the Sun

Experiment Scenario Pavilion of (60 x 40m)

91 Monday, May 12, 2014

Experiment Scenario Outdoor/Night

Result Received Average Power

0.0E+0

2.0E-6

4.0E-6

6.0E-6

8.0E-6

1.0E-5

1.2E-5

1.4E-5

1.6E-5

1.8E-5

2.0E-5

0 10 20 30 40 50 60 70

Distance (m)

Received Average Power over Distance

Axial Distance Received Power

Received Power at 3.5m Offset from Axis

Result Received Messages

0 1 2 3 4 5 6 7 8 9 10

Signal-to-Noise ratio [dB]

25 Chars

50 Chars

100 Chars

256 Chars

Message Length:

(1) Navin Kumar, Domingos Terra; Nuno Lourenço; Luis Nero Alves, and Rui L. Aguiar,” Visible Light Communication for Intelligent Transportation in Road Safety Application”, IEEE IWCMC 2011, Vehicular Communications Symposium, Istanbul, Jul 2011.

Result Received Messages ....

0 10 20 30 40 50 60

Distance (m)

Close Pavilion (Dark Environment)

Bright Sun Light (Noon Hour -Detector Directly Facing Sun Direction) Evening (Sun set) with Street/Road light ON

Street Light point

Street Light Point

0 5 10 15 20 25 30 35 40

Distance [m]

Outdoor Night

Outdoor Night - Height Offset Outdoor DayLight

Environment Test (25

(2,5m)

Result Synchronization Loss

0 10 20 30 40 50

Distance (m)

Environment Test:

Outdoor Night

Outdoor Bright Sun Light

Controlled Dark: Height Offset (1,65m)

Result Packet Error Rate

1,0E-7

1,0E-6

1,0E-5

1,0E-4

1,0E-3

1,0E-2

1,0E-1

0 10 20 30 40 50

Distance (m)

Environment Test:

Control: Dark (Height Offset 1,65m)

Outdoor Bright Sun Light

Outdoor: Night

Result Packet Error Rate ....

98 Monday, May 12, 2014

A £5M Research Programme on Visible Light Communications… – ‘Ultra-parallel visible light communications (UP-VLC)’,

– Collaboration between leading research groups at the Universities of Strathclyde, Edinburgh, St Andrews, Oxford and Cambridge.

– Its basis is the >1Gb/s modulation capability recently shown for individual micro-sized gallium nitride LEDs

Current Status …

http://gow.epsrc.ac.uk/NGBOViewGrant.aspx?GrantRef=EP/K00042X/1 .

LiFi Monday, May 12, 2014

Noise Sources

Challenges & Opportunities

–Minimizing the effect of external noise (artificial or natural)

–Ambient lights effect

– Interference minimization

Uplink design

Long range communication (LoS link required), and many more ....

Challenges & opportunities ..

High data rate (limitation of LED/photo diode switching)

–Different modulation including Optical MIMO

–Adaptive Modulation technique for different applications

–Using Equalization

Front end with gain control

Challenges & Opportunities ..

–V-LAN on aeroplane

–Ubiquitous high data rate communication

Integration with Infrastructure

–RF/VLC Integration

–UP Link / Retrofitting

Challenges & Opportunities …

Though very interesting, but many challenges:

– Uplink design

– Minimizing the effect of external noise (artificial or natural)

– Ambient lights effect

– Front end receiver design with enough dynamic range

– Interference minimization

– High data rate (limitation of LED/photo diode switching)

– Long range communication (LoS link required), and many more ....

Challenges and Research

104 Monday, May 12, 2014

Research: (VLC is at very early (infant) stage)

– Different modulation including Optical MIMO

– Adaptive Modulation technique for different applications

– Front end with gain control

– V-LAN

– V-LAN in aeroplane

– Long distance communication

– Underwater communication

– Ubiquitous high data rate communication

Challenges and Research …..

105 Monday, May 12, 2014

Conclusions

• VLC is a cost effective system with many advantages especially leveraged from advancement in LEDs.

• VLC has prospective applications (still remains unexplored) both indoor and outdoor.

• Use of VLC in ITS as road safety system is a novel idea and directly related to human and material safety.

• Tremendous scope of research available in both VLC as well as ITS.

106 Monday, May 12, 2014

Thank You !

navinkumar@ieee.org

Amrita Vishwa Vidyapeetham Bengaluru Campus

visible light communication in intelligent transportation...

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