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
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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