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Progress in Optical Wireless Communication Giulio Cossu Wajahat Ali Raffaele Corsini Ernesto Ciaramella INFIERI 5th Workshop April 2729 2015 CERN Geneva Summary Overlook on Optical Wireless ID: 365253

geneva infieri 2015 cern infieri geneva cern 2015 april workshop 5th communication led high results lens mbit owc preliminary

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Slide1

Recent Progress in Optical Wireless Communication

Giulio Cossu, Wajahat Ali, Raffaele Corsini, Ernesto Ciaramella

INFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide2

SummaryOverlook

on Optical Wireless Communication (OWC)Motivations and applicationsDevicesVisible Light

Communication

(VLC)

experimentsIndoor applicationsVehicle to vehicle communicationUnderwater communicationOW for HEP and medical imagingPreliminary results

INFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide3

IntroductionINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Optical Wireless (OW):

Wavelengths from infrared to ultraviolet

Free-space as optical medium

Visible Light Communication (VLC):

e.g. synergy between illumination and data transmissionSlide4

Light Emitting Diodes (LEDs)

INFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Phosphorescent white LED

Blue chips

+

phosphorus layer

Limited bandwidth due to the slow phosphor layer (2-3 MHz)

Original frequency response restored with blue filter (10-15 MHz)

RGB white LED

Mix of Red + Green + Blue chips

Full bandwidth without optical filter

Allows Wavelength Division Multiplexing

(

WDM

)

Lower power consumption, lower voltage, longer lifetime, smaller size, cooler operation and

faster responseSlide5

Differences between OW and RF technologiesINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Property of medium

Radio

Optical

Bandwidth regulation

Yes

No

Electromagnetic

interf.YesNo

Power limitationRadio lawEye safety/illumination

Multipath fadingYesNo

Passes though walls

Yes

No

Physical

security

Low

High

Input x(t)

Amplitude

Power (always positive)Detection type

Coherent/IncoherentIncoherentSlide6

Link ConfigurationINFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide7

Modulation formatINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Single-carrier modulation

(power efficiency)

On-Off Keying (OOK)

DC-balanced coding

Multi-carrier modulation

(High speed)

Orthogonal Frequency Division Multiplexing (OFDM)

Discrete Multi-Tone (DMT)

IM/DD

scheme

x(t) > 0

Power efficiency

High

speedSlide8

Discrete Multi-tone –

AdvantagesAdvantages

Spectral

efficiency: bit-power loading

Easy frequency equalizationAble to contrast the multipathSlide9

VLC ApplicationsINFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide10

High-speed OWC link – Introduction

INFIERI 5th Workshop: April 27-29, 2015, CERN GenevaAchieved results

(

2012

) 1 Gbit/s @ 15 cm – Phosphorescent LED (single channel) [Photonics journal](2012) 2.1 Gbit/s @ 15 cm – RGB LED (WDM channel) [ECOC]

(

2012

) 3.4 Gbit/s @ 15 cm – RGB LED (WDM channel)

[Optics Express]

(2014) 5.2 Gbit/s @ 3 m – RGBY LED (WDM channel) [ECOC]

Goal

:

Highest speed operation (with low-cost components)

Minimization of power losses ->

Directed Line-of-sight configuration

Narrow emission beam

Narrow acceptance angle

WDM

operation

(different colors transmit different data)Slide11

High-speed OWC link – Experimental Setup

INFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Downlink: 12

chips (3 for each color). 22°

Lambertian

emission

Uplink:

IR-LED

emitting

at 850 nm, 130° Lambertian emission

DMT signals N=512 subcarriers BW=220 MHz Slide12

High-speed OWC link –

ExperimentINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Summary

: ≥ 5

Gbit

/s with

distance

≤ 3.5 m (

downlink

)

Uplink ranges from 1.1 to 1.5

Gbit

/s (4 -> 1.5 m)

WORLD RECORD Slide13

High-mobility OWC link –

IntroductionINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Achieved results

(

2013) 200 Mbit/s @ 2.4 m – Phosphorescent LED (uni-directional)(2014) 250 Mbit/s @ 2 m – Phosphorescent LED/IR-LED (bi-directional)

(

2014

)

400 Mbit/s @ 2 m

– RGB LED/IR-LED (bi-directional)

Goal: High speed operation in high mobility

Non Directed Line-of-sight schemeTrade-off between diffuse links and high speed of LOS links.

Scenario closer to typical indoor topology: synergy illumination and data

Robust to indoor ambient lightSlide14

Custom

RGB LED

: blue @ 470 nm

(

local minimum of the Ph-LED)Aux LED: Cool white phosphoroscent

LED

(to emulate ambient light)

120°

Lambertian

emissionDMT signals N=512 subcarriers BW=75 MHz

Tx

Downlink

High-

mobility

OWC link

Experimental

setupSlide15

High-mobility OWC link

– ExperimentINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Measurement conditions

Vertical distance between

ceiling and desktop: h = 2 m

Fixed 500 lx @

Rx

BER

< 1,48∙10

-3 (error-free after FEC decoding)Measurements for downlink and uplink:Maximum data rateφ=ψ=0° (R=0 m),

Data rates: 400 Mbit/s (downlink) – 380 Mbit/s (uplink)

φ=ψ =45° (R=2 m)

Data rates: 200 Mbit/s (downlink and uplink)

Hot spot having

r

≤ 2 m (≈12 m

2

) with a maximum of 400 Mbit/s (at the center) and a guaranteed data rate of 200 Mbit/s.Slide16

INFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Intelligent Transport System (ITS)

Increase safety, reduce congestion, enhancing mobility

Vehicle-to-Infrastructure (V2I): roadside sensor, traffic lights

Vehicle-to-Vehicle

(V2V)

: safety-critical communication

Common Radio Frequency (RF) solution

IEEE 802.11-based protocols: 5.9 GHz bandwidthNetwork congestion because of isotropic nature of the radio-waves

«Broadcast storm»

Optical Wireless

Low cost and limited impact: LEDs already present on the cars

Free from broadcast storm: strong directionalitySlide17

Car-to-Car communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

CONFIDENTIAL

«Broadcast

storm

»Slide18

Car-to-Car communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide19

Car-to-Car communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Step-like behavior

:

No error until the distance is such that the signal is higher than the serial port sensitivity

Maximum

distance

(m)

1

No lens Tx – No lens Rx0,25

218° lens Tx – No lens

Rx0,53

No

lens

Tx

– Lens

Rx

2,6444°

lens Tx – Lens Rx

14,55

18° lens Tx – Lens Rx

31Slide20

Underwater communication - Introduction

INFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Underwater monitoring exploiting

vehicles in cooperation

needs of

data exchange

among vehicles

Radio waves

extremely attenuated

in waterAcoustic modems for long distance suffer low data rate (hundreds bit/s)latency (v=1500 m/s)high cost

Optical

Underwater

CommunicationSlide21

Underwater communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Almost 7 hours BER

monitoring

Up to 100 Mbit/s

Error

free after FEC decodingSlide22

OWC for INFIERI applicationsOWC for Medical Imaging:

To avoid strong electromagnetic interference in PET detectorsWe performed some preliminary results for the joint project with University Carlos 3 of Madrid. INFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide23

Board-to-Board communication–

IntroductionOWC for HEPDesign a Multi Gigabit OWC system for particles detectors (CMS

used as a case study

)

Requirements:Transmission distance: 10 cmTransmission bitrate: 2.5 Gbit/sTarget bit error rate (BER): 10-9HEP

environment

INFIERI 5th Workshop: April 27-29, 2015, CERN GenevaSlide24

Board-to-Board communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN GenevaPreliminary experimental results:

Tx

: Vertical Cavity Surface Emitting Laser (VCSEL)

Relatively high output optical power: 0 dBm (1 mW)Medium divergence angle: 16°

Emission wavelength: 1550 nm (no absorption with silica material)

Rx: Photodiode

Active area: 60 µm diameter

Ball lens: 1.5 mm diameter

Transmission link up to 1 cm approx. Ray-tracing simulation (TracePro)in order to optimize the receiverSlide25

Board-to-Board communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Target distance: 10 cm

Target bitrate: 2.5

Gbit/sTarget bit error rate (BER): 10-9

Simulation

shows 2 dB

power

margin respect to our transmitted powerAs expected, margin increases with bigger ball lens (together with tolerance to misalignment)Slide26

Board-to-Board communication – Preliminary

resultsINFIERI 5th Workshop: April 27-29, 2015, CERN Geneva

Ball

lens

Photodiode

misalignment

Current condition

22 dB

power penalty (~150 times) Slide27

Conclusions

Optical wireless system as new technology alternative to RFMain application: communication -> Visible Light CommunicationHigh-speed

indoor communication

5.2

Gbit/s WDM approach in directed-LOS @ 3 m (RECORD)400 Mbit/s in Non-directed LOS @ 2 m (RECORD)Vehicles to vehicles communicationSecurity message up to

31 m

exploiting

1 LED

Underwater communication

Up to 100 Mbit/s error-free in 2.5 m underwater Medical ImagingPreliminary results: tolerance measurement at 0.5-1 m distanceHigh Energy PhysicsPreliminary results: 1 cm transmission. Simulated: 10 cm feasibleSlide28

Thanks for

your attentiong.cossu@sssup.it