visible light communication in the intelligent transportation systems
TRANSCRIPT
Visible Light Communication in Intelligent Transportation
Systems Navin Kumar, PhD
Sr. Member IEEE, IAENG(HK), IETE, IE(India)
Amrita University, Bangalore
Monday, May 12, 2014
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Amrita Vishwa Vidyapeetham Bengaluru Campus
Outline
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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.
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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.
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Identified Benefits
Time Savings
Improved Throughput
Reduced Crashes and Fatalities
Cost effectiveness
Increased Customer Satisfaction
Energy and Environmental Benefits
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
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
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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).
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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:
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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
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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)
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Application: Bus Information System
• Public Transport Information
– Countdown: Real-time Bus Stop Information
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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
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Application: Incident Management
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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
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Application scenario: IntelligentVehicles & Infrastructure
Driver Assistance Systems
Collision Avoidance Systems
Collision Notification Systems
Electronic payment and pricing
Emergency management
Transit Management
Freeway Management
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Application scenario: Intelligent Infrastructure
Road Weather Management
Roadway Operation and Maintenance
Information Management Traveler
information Crash Prevention
and Safety
Commercial Vehicle operation
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Intelligent Transportation System
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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 )
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VC Service Scenario
Sensor
Access Point
Car to Car
Car to Road
Home Network
Roadside Assistance
Service Provider
Sensor
IMS
InternetRadioAccess
Network
WLAN, WiMAX,
GSM, GPRS,3G & B3G
Sensor
Sensor
PoC
PresenceeCall
IPTV
Context–AwareService
Provisioning
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VC Service Integration
WLAN
WiMAX
UMTS
GPRS
GSM
IMSCore
Network
Home Network
Radio
Access
Network
PoCPresence
eCall IPTV
Context–AwareService
Provisioning
Internet
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Advanced Traffic Management Systems
Photo from the Human-Computer Interaction Lab: University of Maryland Monday, May 12, 2014 24 Monday, May 12, 2014
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WSDOT Traffic Systems Management Center
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Advanced Traveler Information Systems
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Advanced Public Transportation Systems
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Advanced Vehicle Control Systems
Intelligent
Cruise Control (ICC)
System
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ITS Strategic Plan – Research Questions & Framework
Ap
plic
atio
ns
Tech
no
logy
P
olic
y
ALL MUST BE ANSWERED TO BE DEPLOYABLE
77%
18%
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?
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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…
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What is VLC?
Monday, May 12, 2014
31 http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Introduction
Visible Light Communication ?
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0 1 0
1
0 1 0
1
0 1
1 0
1
0
1 0 0 1
1 0
1
0 1
0
0 1
1 1
0
0 1
Tx
Rx
Communication using visible light Wirelessly.
Light Emitting Source (one component)
Light Detector (one component)
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Introduction: History
• Smoke signals of the ancient tribes
• The use of fire or lamp Beacon fire, lighthouse, ship-to-ship comm.
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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 …
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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.
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Facts, Figures, and Trends of Wireless Networks and Technology
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Several Technologies move in the same direction
4G Many Access
Networks
5G
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Introduction
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Monday, May 12, 2014 Navin
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Introduction • Wireless data transmission via optical carriers:
opportunity, many yet unexplored.
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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.
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Frequency Spectrum
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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
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
Low Frequency (High wavelength)
Large Coverage Mobility
High Frequency (Small wavelength)
High Bandwidth Security
IrDA : 334THz(900nm) to 353THz (850nm) Monday, May 12, 2014
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Introduction … • Variations of OWC can be employed in a
diverse range of communication applications:
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outdoor inter-building links (on the order of kilometres)
very short-range (on the order of millimetres) optical interconnects within integrated circuits
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Optical Wireless Communication and Systems
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• 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).
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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.
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
OWC – Free Space Optics
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- 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
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FSO: Applications
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Fig.: A Simple Point-to-point FSO Connection
Fig.: FSO Corporate Networks
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FSO: Applications
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FSO: System Requirement and Design Issues
Tracking
• The requirements for tracking systems in carrier-class free-space optics systems.
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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
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FSO: System Requirement and Design Issues
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Fig.: Atmospheric Issues
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FSO: System Requirement and Design Issues ….
• Ex.: Attenuation because of Fog/Snow storm
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Taken from - Scott Bloom, The Physics of Free-space optics, white paper AirFiber Inc.
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FSO: Overall Functional Blocks
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Transmitter Laser, Lens, Driver
Receiver
Photo Detector Front End Amplifier
Tracking
Microprocessor based tracking/alignment system
Fig.: Overall FSO Block Diagram
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BASIC COMPONENTS: OPTICAL WIRELESS
Transmitter
•
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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
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OWC – Basic Components …
Receiver consists of:
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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
AMP
Amplifier and following processing
Concentrator or Lens Collection of radiation
Preamplifier (or number of preamplifiers) normally Transimpedance Amp. and signal processing
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OWC Configuration
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Lin
e-o
f-si
ght
(Lo
S)
Non LoS
BASIC CONFIGURATION: LoS or DIFFUSE
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Configuration Characteristics
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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
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OWC Characteristics
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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
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Development
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Optimal Integration into 4G Infrastructures
Emerging Area Visible Light Communication
Monday, May 12, 2014 Navin
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
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
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
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
VLC …
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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
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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……….
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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.
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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.
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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).
&
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VLC Motivation – LED Illumination
0
20
40
60
80
100
120
140
160
180
200
2 7 1020
3040
47
115
136
186
200lm/WLuminous Efficacy
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
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VLC Motivation –LED Advancement
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Therefore, Visible Light emitted from LED can be modulated to send information data i.e. Simultaneous operation of Lighting and Switching.
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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]
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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
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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
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VLC Characteristics
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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.
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VLC Characteristics
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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
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RF or Optical Link?
OW OW
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VLC Applications
Monday, May 12, 2014 Navin
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
INDOOR
VLC Applications …
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VLC Applications: Indoor
LiFi Configuration
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VLC Applications: Indoor …
Music Broadcast Parallel Transmission (Taken
from Nakagawa Lab, Japan)
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VLC Applications: Outdoor UNDERWATER
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VLC Applications: Outdoor …
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INTELLIGENT TRANSPORTATION SYSTEMS (ITS)
VLC Applications: Outdoor …
5m
7m
3m
30mLED Lights
A scenario of VLC in ITS Ubiquitous Communication with Road Illumination
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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
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VLC Applications: ITS-Road Safety
VLC as Advanced Driver Assistance System: pls clk to
see
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Overall Architecture
VLC System
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Block Diagram: Conceptual Design
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Emitter Characteristics and Model:
LED (Lambertian Model):
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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
(1)
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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
±10
±2
-DC Balanced -Low resources -Easy Implementation -PG = 10dB
Barker +1+1+1-1-1-1+1-1-1+1-1
±11
±1
-Nearly DC Bal. -High Resource -Complex -PG = 10.4dB
PN Code
Input Data
MicroBlaze
DPLB
IPLBILMB
DLMB INTR
BRAM
INTC UART
LMB
LMB
PLBClock
IRQ Lines
50 MHzMB
PLBLMB
SIK
DataBuffer
+Frame
Processing
Binary
DSSS EMITTER CORE
AWGN(channel SNR
simulation)
Bipolar to
Unipolar
Output to Optoelectronics
GPIO
Frame
Processing
ClockManager
Unipolar to Bipolar
ADC
GPIO
Output Data
MicroBlaze
DPLB
IPLB ILMB
DLMBINTR
BRAM
INTCUART
LMB
LMB
PLB Clock
IRQ Lines
50 MHzMBPLBLMB
DSSS RECEIVER CORE
Input from Optoelectronics
SYNC
Matched Filter
PN Code
Treshold Detector
PER Bipolar to Unipolar
EMITTER ARCHITECTURE RECEIVER ARCHITECTURE
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Conceptual Design ....
Layer Architecture and ITS Integration ..
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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
Monday, May 12, 2014 Navin
Emitter Model and Design
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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
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Modulation Analysis
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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)
Monday, May 12, 2014 Navin
FPGA & Hardware Implementation
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PN Code
Input Data
MicroBlaze
DPLB
IPLBILMB
DLMB INTR
BRAM
INTC UART
LMB
LMB
PLBClock
IRQ Lines
50 MHzMB
PLBLMB
SIK
DataBuffer
+Frame
Processing
Binary
DSSS EMITTER CORE
AWGN(channel SNR
simulation)
Bipolar to
Unipolar
Output to Optoelectronics
GPIO
Frame
Processing
ClockManager
Unipolar to Bipolar
ADC
GPIO
Output Data
MicroBlaze
DPLB
IPLB ILMB
DLMBINTR
BRAM
INTCUART
LMB
LMB
PLB Clock
IRQ Lines
50 MHzMBPLBLMB
DSSS RECEIVER CORE
Input from Optoelectronics
SYNC
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
±10
±2
-DC Balanced -Low resources -Easy Implementation -PG = 10dB
Barker +1+1+1-1-1-1+1-1-1+1-1
±11
±1
-Nearly DC Bal. -High Resource -Complex -PG = 10.4dB
EMITTER ARCHITECTURE RECEIVER ARCHITECTURE
Monday, May 12, 2014 Navin
VLC Prototype
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VLC Receiver
OPTOELECTRONICS & FPGA
Receiver
FPGA Rx
FPGA Tx
OPTOELECTRONICS AND FPGA DEVELOPMENT
Monday, May 12, 2014 Navin
VLC Prototype Experiment in Lab
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(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
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Experiment Scenario (Lab Environment)
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Distance Tx –Rx (2.5m) Height (0.85m) -Lights ON -Lights OFF
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Experiment Scenario Outdoor/Daylight
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Bright Sky, Directly Under Sun at Noon time – Detector facing the Sun
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Experiment Scenario Pavilion of (60 x 40m)
91 Monday, May 12, 2014
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http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Experiment Scenario Outdoor/Night
92
Monday, May 12, 2014 Navin
Result Received Average Power
93
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
Re
ceiv
ed
Po
we
r (W
/cm
2)
Distance (m)
Received Average Power over Distance
Axial Distance Received Power
Received Power at 3.5m Offset from Axis
Monday, May 12, 2014 Navin
Result Received Messages
94
0
10
20
30
40
50
60
70
80
90
100
0 1 2 3 4 5 6 7 8 9 10
Me
ssag
e H
it [
%]
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.
Monday, May 12, 2014 Navin
Result Received Messages ....
95
0
10
20
30
40
50
60
70
80
90
100
0 10 20 30 40 50 60
Me
ssag
e R
ece
ive
d (
%)
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
20
40
60
80
100
0 5 10 15 20 25 30 35 40
Me
ssag
e H
it [
%]
Distance [m]
Outdoor Night
Outdoor Night - Height Offset Outdoor DayLight
Environment Test (25
(2,5m)
Monday, May 12, 2014 Navin
Result Synchronization Loss
96
0
5000
10000
15000
20000
25000
30000
35000
40000
45000
50000
0 10 20 30 40 50
Syn
chro
niz
atio
n L
oss
es
Distance (m)
Environment Test:
Outdoor Night
Outdoor Bright Sun Light
Controlled Dark: Height Offset (1,65m)
Monday, May 12, 2014 Navin
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Result Packet Error Rate
97
1,0E-7
1,0E-6
1,0E-5
1,0E-4
1,0E-3
1,0E-2
1,0E-1
1,0E0
0 10 20 30 40 50
Pac
ket
Erro
r R
ate
Distance (m)
Environment Test:
Control: Dark (Height Offset 1,65m)
Outdoor Bright Sun Light
Outdoor: Night
Monday, May 12, 2014 Navin
Result Packet Error Rate ....
98 Monday, May 12, 2014
Navin
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
99
Current Status …
http://gow.epsrc.ac.uk/NGBOViewGrant.aspx?GrantRef=EP/K00042X/1 .
LiFi Monday, May 12, 2014
Navin
Noise Sources
100
Challenges & Opportunities
Monday, May 12, 2014 Navin
–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 ....
101
Challenges & opportunities ..
Monday, May 12, 2014 Navin
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
102
Challenges & Opportunities ..
Monday, May 12, 2014 Navin
V-LAN
–V-LAN on aeroplane
–Ubiquitous high data rate communication
Integration with Infrastructure
–RF/VLC Integration
–UP Link / Retrofitting
103
Challenges & Opportunities …
Monday, May 12, 2014 Navin
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
Navin
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
Navin
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
Navin
107
Thank You !
Monday, May 12, 2014 Navin
http://icc2014.ieee-icc.org/2014/private/programTutorials.html
Amrita Vishwa Vidyapeetham Bengaluru Campus