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࢖ࣥࢱ࣮ࢿࢵࢺࡢᬑཬࡸᦠᖏ㟁ヰࡢᬑཬ࡟క࠸ࠊ▐᫬࡟኱ᐜ㔞ࡢ᝟ሗࢆᚓࡿࡇ࡜ࡀ࡛ࡁࠊ
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Ᏹᐂ㏻ಙࠊᆅୖ㏻ಙࠊỈ୰㏻ಙ࡞࡝ᖜᗈ࠸ศ㔝࡟㐺⏝ྍ⬟࡛࠶ࡿࠋࡇࢀࡽࡢග✵㛫㏻ಙࢩ
ࢫࢸ࣒࡛ࡣࠊ/' ࠾ࡼࡧ /(' ࡟ࡼࡗ࡚㏻ಙࢩࢫࢸ࣒ࡀᐇ⌧ࡉࢀࡿࠋ
ᮏ✏࡛ࡣࠊ/' ࡜ /(' ࢆ⏝࠸ࡓග✵㛫㏻ಙᢏ⾡ࡢⓎᒎࡢṔྐࠊ⌧≧࡜௒ᚋࡢᒎ㛤࡟ࡘ࠸࡚⤂௓ࡍࡿࠋOVERVIEW FOR OPTICALWIRELESS COMMUNICATION
16 December 2017
Mitsuji Matsumoto
Waseda University, Japan
mmatsumoto@waseda.jp

2XWOLQH
 Introduction
 Position of OWC(optical wireless system)

 IRC(Infrared communication system) VLC(Visible light communication system) FSO(Free space optical wireless system) Conclusion
2

Introduction• Changes in the social environment,
anywhere, anytime, high speed/high quality, easy and seamless,various service/application connections are demanded.
㻌 Wireless technology (Radio/Optical) is promising to solve thesechallenges.
• Radio and optical have advantages and disadvantages, but here
I introduce the area of OWC (optical Wireless Communication).
• In the old wireless standard of the microwave relay system,
BERӌ0.01%/2,500km has been required and the value of the callloss rate is close to the (3%) of the whole communication networkor mobile phone.
• Conventional optical wireless communication has been used as acomplementary.
• Areas where best effort communication, or standards can berelaxed.

Characteristics of OWC• The radiation beam of light travels straight at a
- by wide angle (short distance ) or
- by narrow angle (long distance) communication.
• Wide range of application fields of light include- space(FSO), ground(FSO, VLC, IRC), underwater(VLC)• Further research on- transmitter/receiver optical components,- lightwave propagation technology etc. are important• For popularization, Standardization is also important.
4

Current trend for OWC in Communication Distance and Speed
Data rate
10 Gbps
1 Gbpsps

1.28Tbps FSO by
Sss’a, NICT, Waseda

3Gbps VisibleV
lightcommuncommunications
Fraunhofe
Fraunhofer, HHI

FSO

5-10Gbps IR
Fraunhofer
OpticalWLAN

100 Mbps

Optical fiber
communication
Long distancecommunication

UWB

1
150MbpsVLCL
Li-Fi LAN Fudan

WiMAX

WLAN
a/b/g

IrDA
10 Mbps

VLCIrDAbps
1 MbpsBluetoothB

ZigBee100 Kbps

Near Field
Comm.
C
Comm
1m
10 m

Personal Area
Comm.

Ir Io
100 m

1 km

10 km

Communication distanceexp> D (O )L@
100 kmAppearance of Infrared Data Communication
Desktop PC

Mobile terminal boom in the 1990's:
Newton (PDA),Electronic notebook ,PersonalCommunicator:
Start : Windows 95 OS machine

Information exchange and printout with the desktop PC(conventionally cable connection, FD exchange)

Printer

Focusing on infrared technology
which has been widely used forremote control of home TV, stereo,
air conditioner and so on for the past,
it is applied for IR communication.

Mobile PC

IrDA launched: In 1993 the consortium,
De facto standardization organization
Members: approx.100 (U.S.), 43(Japan)

User Scene
Showing pictures on the Big
Screen.

Using presentation data fromown PDA or cell phone.

IrDA Roadmap
short distance/1m/high speed
UFIR
VFIR
FIR
MIR
SIR

Single Image
Content

Text baseContents

1Mbps

100kbps
1994

Single Music
Content

Hyper Multimedia
Instant Synchronization

Video / MusicAlbum Contents

10Mbps

1995

100Mbps

2006

1998

1998-2004 IrMC/IrFM
HP IBM MS

GigaIR

1Gbps
2009

2005-2IrMC/IrSimple

2009- Giga-IR

UFIR:2006
SHARP,WU,NTT,
Stanley, EG䠈

Giga-IR:2009
KDDI,Rohm,Panasonic,
W.U., CEC. EG

IrSimple 2005
SHARP NTTDocomo䠈
ITX-EG,Waseda Univ

8

IrDA/VLC Protocol Stack
OSI 7

Personal Area Network
Applications

OSI 6

Multimediald Informationf
Broadcast Information

OSI 5
OSI 4
OSI 3
OSI 2
OSI 1

OBEXTM
TinyTPInternet
SessionProtocols

Other
SessionProtocols

TCP/IPUDP

OtherTransport
Protocols

IrSimple

IrLAMP

upper layers

IrDA/VLC Physical Layer
Inverted 4PPM

Manchester Encoding
9

Infrared circuit diagram,%03&㸭$7&RQSDWLEOH

㻌 䠥䠮
Mod.

IR Transmit LED
Circuit㻌 䠥䠮DemIR receive
circuit

UART
Universal Asynchronous
Receiver and Transmitter

115.2 kb/s

䠬䠠

1 frame:10 bits㻌 㻵㻾㻌㻲㼞㼍㼙㼑㻌 㼁㻭㻾㼀㻌㻲㼞㼍㼙㼑㻿㼠㼍㼞㼠㻌㻌
㻮㼕㼠㻌㻰㼍㼠㼍㻌㻮㼕㼠㼟

㻜
㻜

㻝

㻜

㻝

㻜

㻜

㻝

㻿㼠㼍㼞㼠㻌㻮㼕㼠㻌 㻚㻌㼁㻭㻾㼀㻌㻲㼞㼍㼙㼑

㻝

㻜

㻝
㻮㼕㼠

㻿㼠㼛㼜㻌㻮㼕㼠㻌

㼀㼕㼙㼑

㻝

㻿㼠㼛㼜㻌
㻌㻮㼕㼠㻌

㻰㼍㼠㼍㻌㻮㼕㼠㼟
㻜

㻝

㻜

㻜

㻝

㻝


7 㻌㻵㻾㻌㻲㼞㼍㼙㼑


㻜

㻝

㻼㼡㼘㼟㼑㻌㼃㼕㼐㼠㼔㻌㻩㻟㻛㻝㻢㻌㻮㼕㼠㻌㼀㼕㼙㼑㻵㼞㻿㼕㼙㼜㼘㼑㻌㻔䠐㼢㼍㼘㼡㼑㻌㻼㻼㻹㻘㻌㻠㻹㼎㼜㼟㻕㻌
9.6 kbps - 1.152Mbps

7


0

1

0

Data bit
Pair (DBP)
00
01
10
11

㹒

4Mbps(䠐㻙㻼㻼㻹㻕

7

00

T=500 ns

10

01

125

Chip

11

4PPM Data
Symbol(DD)
1000
0100
0010
0001

High efficiency technical challenges
Station A

Station B
Download Data
Activity Time
DDAT(A)
Dead Time

Processing
Bitmap info

Turn Around
Time TAT(A)Data Acknowledge
DA(B)Turn Around
Time TAT(B)

Decoding
Bitmap info

Download Data
Activity Time
DDAT(A)

12

Comparison between early stage IrDA and IrSimple systems
Early stage system in case of 4Mbps

Approx. 6 sec
IrSimple system In case of 4Mbps

Approx. 1 sec
䖂500KB photo transfer
13Connectivity utilization model• Conscious connection– Point-to-Point Usage• Personal information transfer (vcard, vcal, etc…)• User initiated synchronization• Financial messaging• Walk-up printing• Unconscious connection• Voice• Network Synchronization• Shared access device connectivity–Ericsson, Intel, IBM, Nokia, Toshiba (1800 companies)

Market conditions –maturity of IrDA and Bluetooth
Hype‘Intersection of Reality’

Peak of Inflated
Expectations - BT
Peak of Inflated
Expectations - IR

Bluetooth

1997

IrDA

Plateau of
Productivity

Slope ofEnlightenment
2001
1995
Technology
Trigger - IR

Mid-2003

Mid-1998
Trough of
Disillusionment

Source: Gartner Group / IrDA

Maturity

Product technology roadmap 䠄IrDA)
Transfer Speed(Mbps)

㻌

1000

㻌

㻌

㻌

LD

㻌

㻌

Diffusion LD

100

㻌

㻌

㻌

1

16Mbps:VFIR

㻌
Audio

㻌

4Mbps:FIR㻌

UFIR,IrBurst(Diffusion LD)㻌White LED

10

GigaIR

㻌

VLC

㻌

㻌

㻌

㻌

㻝㻥㻥㻜㻌㻌㻌㻌㻌㻌㻌㻌 㻌 㻌㻝㻥㻥㻡㻌㻌㻌㻌㻌㻌㻌㻌 㻌 㻌㻞㻜㻜㻜㻌㻌㻌㻌㻌㻌 㻌 㻌㻌㻞㻜㻜㻡㻌 㻌 㻌 㻌 㻌 㻌 㻞㻜㻝㻜
115kbps:SIR

㻌 㻌

㻌

16

Development of Eye Safe Laser Diode㻰㼕㼒㼒㼡㼟㼑㼐㻌㼘㼕㼓㼔㼠㻸㻰㻌㼠㼕㼜㻌

㻴㼑㼍㼠㻌㼟㼕㼚㼗㻌•the spot size:1000 times•measured beam diameter:4mm•100Mbps/1m

㻸㼕㼓㼔㼠㻌㼐㼕㼒㼒㼡㼟㼑㼞㻌㻸㻰㻌㼜㼍㼏㼗㼍㼓㼑㻌

Same Approach is possible for miniature IrDA Unit
Source Size of >2mm will bepossible with optimized lens 㻌
Operating Current is < 1/3
compared with LED
Modulation speed is >100MHz

100Mbps IrDA

Challenges of IR communication• Speeding up of Light Emitting Element (LD, LED)
• Wide range Connectivity(Speed, Distance, Radiation angle)• FDX(Full duplex transmission) and Throughput• High Speed Transmission protocol(Short Confirmation, Turn Around Time)• Interoperability (Standardization)• Miniaturization (small size)• Killer Application
19

Visible Light Communication (VLC)• Visible Light communication is a wireless communication
technology that uses light that is visible to humans• Main features of VLC(1) LED lights will be used everywhere(2) Infrastructure is necessary for location services(3) Easy identification of places or things(4) There is no regulation for visible light
communication so far

20

Visible Light Communication (VLC)
Definition :Electromagnetic waves of wavelength380-780 nm visible to human eyes.
When it comes into the human eye,
it is recognized in the brain as color,each color has its own wavelength.

LED (semiconductor element emitting)Transparent
epoxy resin䢢White light䢢䣕䣧䣣䣮䣫䣰䣩䢢
䣴䣧䣵䣫䣰䢢䢢
䢭䢢䣻䣧䣮䣮䣱䣹䢢䢢䣲䣪䣱䣵䣲䣪䣱䣴䢢P䢢
N䢢

Emission䢢PN junction䢢

Blue LED chip䢢

Visible light wavelength

Anode+

Cathode-Light emitting method of white LED

Yellow
phosphorWhite light emission

White light emission

White light emission

R

Blue
LED

BG mix.

Blue LED+ Yellow phosphor
Complementary color

White with one-chip LED withblue/green color mixture䢢

G

B

White by combination of
red / green / blue LED䢢
10

Origin of visible light wireless communication
Sun Light
9RLFH2XWSXW

Voice Input

Visible Light Transmitter䢢

Visible Light Receiver䣃䣤䣱䣷䣶䢢䢴䢲䢲䣯䢢
Sun Light
Voice Input

Lens

Reflector
Selenium

glass
Lens

A.G.Bell’s Photohone (1880)

Parabolic mirror

Voice Output
23

Optical accesspoint

VLC characteristics
y Emits electromagnetic waves focusing on single wavelengthwith specific photons.
y Ease of directivity control
y Luminous efficiency 30 - 100 (lm / W)y Regular light spectrum
y Fast response to current (short-time strobe lighting)эCommunication possible
y Light amplitude / intensity (light and dark)y Optical wavelength (color)y Optical phase (shape)

A modulation scheme effective forillumination optical communication
䛆Basic requirement䛇• Maximize lighting characteristics• Secure reception average power that can ensure desired SNR (BER)• It is less susceptible to disturbance illumination light (fluorescent noise etc.)• Even if any kind of data is modulated, a mechanism that always lights once-------- 4 PPM (Pulse Position Modulation)[Modulation method]
Turn On䢢
7XUQoff䢢

slot

7XUQon䢢slot

7XUQoff䢢

25

Light receiving element for
illumination optical communication
Basic requirement• High sensitivity (receiving ability of weak optical signal)• High-speed response (increase in code transmission speed)• Low noise (SNR degradation of optical signal is small)• High quantum efficiency (large number of carriers, increase insignal quantity)䠗
Main light receiving element:• Single PD/APD (APD: about 3-5 dB higher sensitivity than PD)• Two-dimensional image sensor (array of PD / APD)

Comparison of light receiving methods ofsingle and two-dimensional elements䣕䣫䣩䣰䣣䣮䢢䣕䣱䣷䣴䣥䣧䢢
䣕䣉1

SG2(noise source)䢢

䣕䣉1

SG2(noise source)䢢

Spatial lightinterference range
Sa

Ss

Single PD light receiving surface Ss• Easy structure, high speed
operation by element;• It is weak against influence of
background light noise due tosurface light reception, making
it difficult to communicate overlong distances.

Image sensor receiving surface Sa• Point light reception is strong against the influence of
background light noise and communication at long
distance is possible;• Since the multiple signals are processed
simultaneously, the load is greatly highFast communication is difficult;• Flicker occurs at low speed (frame rate is several tensof kHz).
20

Optical Wireless LAN(Omnidirectional system structure)
Receiving PLC modem

凚 Access the Internet source) 䢢LED lighting
fixtureDown VLC
Up IR

Transmitting
PLC modem

DonglePC or Internet

Wi-Fi and Li-Fi
Omnidirectional

Optical Accesspoint(LED lighting)Access-point
Ethernet

Ethernet

Radio
wave

ClientWireless LAN card(a) Wi-Fi

Light
wave

ClientOpticalwireless dongle(b) Li-Fi

Challenges
Master unit

Master unit

VLC

VLC

VLC

VLC
Collision
DetectT1

Shared space

T2

T1(a) no collision

Shared space

T2(b) collisionPrinciple of spatial light CSMA / CD (CA):IEEE 802.3 CSMA/CD (CA): carrier sense multiple access with collision detection/avoidance

Under water communication

Photos provided by Toyo Electric.

Comparison of underwater data radio
propagation method
Radio wave

sound waves

light waves

Distance

Long range
transmission
possible with low
frequency

Compared to lightand radio waves,attenuation is small
and it can betransmitted far away

Damping due toabsorption /scattering / lightshielding, shortdistance (average
about 15 - 100 m)

speed

There is a speed
limit. Faster than inair (average about
1500 m / s)

Speed depends onwater pressure andwater temperatureSound velocity
minimum around1000 m (approx.
1470 m / s)

capacity

The amount of
information that canbe transmitted withas low frequency as
possible is small

Large capacity (easyto control due tovisibility)

For seawater and freshwater, fresh water has longer propagation distance at any frequency

Frequency Characteristic in under sea

Distilled Water

VLC
X-ray
Electromagnetic

MW

UV

IR
Underwater
sonic

0.5
Intensities (a.u.)

Absorption
attenuation

1.0

Frequency (Hz)Attenuation of electromagnetic waves(Radio wave/Light) and sound waves
in seawater

0.0
1.0

0

2000

4000

6000

8000

10000
450nm
550nm
650nm

Bay area
0.5
0.0
500

1000
1500
Distances (cm)2000

Spectral decay of transmission distanceby extinction coefficient

F/Fo䠙e-cL
C(Extinction co.) 䠙a(Absorption co.)䠇b(Scattering co.)Fo(Incident parallel light flux)

Ocean environment VLC system(Submarine exploration) by JAMSTEC

Data uplink by VLC

Data uplink by VLC

VLC area
Max Comm.
Distance:100m
Speed 1Mbps TWA

Submarine station

Marine environment visible light wireless communication system

9/&GDWDWUDQVIHUEHWZHHQ$89 DXWRQRPRXVXQGHUZDWHUYHKLFOH᧥DQG8QGHU6HD6WDWLRQ

Data

Wavelength
selective
adaptation

Underwater Light

Transmitter

Wavelength selective optical filter

Lighting & Carrier
by White light

SeawaterPD

Data

Receiver1000 times/6500m

1200 times/
6500m/
3 person"Shinkai 6500" is a submersible
survey ship capable of dive to
6,500 m in depth (1989) -JAMSTEC

Adaptive measures for marine environmentReference:An overview on high speed opticalwireless/light communications

doc.: IEEE 802.11-17/0962r2

The IEEE 802 OWC standards
OWC/LC

Very High Data rates(complex pro
protocolsols )WiFi area

802.15.13- MAC based on
802.15Specialty Areas
eas(Low Volumes)

Potential LC for 802.11- MAC based on 802.11

Mass Marke
Market(Very High Volumes)

802.15.72011

Optical Camera
Communications in
802.15.7m- Limited MAC relevance

Very Low Data rates(simple protocols )Submission

Slide 36

Nikola Serafimovski (pureLiFi)

IEEE 802.11 can bring high-speed LC to the mass market
faster and in a more comprehensive manner other SDO
ITU-T Study Group G.vlc• Based on G.hn – Home Networking standard• Customer Premises Equipment may use G.hn
802.15.7r1• Originally based on 802.15.4 - Not designed for networking, e.g.,
No 48 bit MAC address, different security,…
802.15.13• Based on 802.15.7r1 with focus on Muli- Gigabit/s Optical WirelessCommunications suitable for speciality wireless networks
ProblemNeither effort has the comprehensive ecosystem of partners required
for mass market adoption of LC.
Proposed – 802.11 has unique ecosystem• Chipset vendors, Network Infrastructure, Device Integrators,• End Customer and Operatorsdoc.: IEEE 802.11-17/0962r2

LC can address a number of different use-cases

This is just an illustration of the possible use-cases.
Additional use-cases such as in-home, virtual reality and more can also be considered.
Submission

July 2017

Slide 38

Nikola Serafimovski (pureLiFi)

FSO Application scenarios
Depending on the deployment scenario andapplication, the FSO communication system
is suitable for terrestrial, ocean and space
based communication.
For space-based communication,
 Deep space communication
 Inter-satellite communication
 Satellite to Ground communication
 Manned spacecraft ]In the case of terrestrial communication,
 Metro network extension
 Last mile access Enterprise connectivity
 Remote located settlements
 Fiber backup
 Temporary line in case of disaster, etc.

FSO

Internet

Metro network
extension

Mountainous
terrain
RoFSO
transceiver
remote basestationFTTH

Backhaul(~5 km)䠢䠰䠰䠤䚸䠝䠠䠯䠨

Remote locatedsettlements

No fiber connectivity
RoFSO link
Optical fiber link
RF based links
RoFSO transceiver39
9What are the challenges of FSO?
Atmosphericturbulence

Transmitting
Terminal

Receiving
Terminal

Optical fiber

1550nm

Optical fiber
Opt. Beam

1550nm How to realize Ultra High Speed and Reliable
Optical Link through the atmosphere, based on
the compatibility with existing fiber infrastructureusing 1550 nm wavelength40

Direct coupling high-speed FSO system
Transmitting
ModuleAtmosphericTurbulence

Optical fiber

Receiving
ModuleOptical fiber

Opt. Beam

10μm

1550nmBy Direct coupling between optical fiber and free-space••••

No O/E & E/O conversion
Uses 1550nm wavelength
Compatibility with existing fiber infrastructure.
Protocol and data rate independent. Seamless connection of spaceand optical fiber.
• broad bandwidth (InGaAs) and no power limitations• Tracking control mechanism
 Provide high speed physical transmission path and services equivalent
to optical fiber.
41

Influence of atmosphere on FSO
 Because transmission environment of FSO is the atmosphere, so there
are many influences on the system performance, including attenuation
due to rain, fog, snow and especially turbulence due to the variation oftemperature and pressure, etc.
 Among them, effects of fog and turbulence are severe. However, in thecase of fog, we can overcome by some way for example increasetransmission power or pre-amplifier gain.
 For many cases of practical problem, optical turbulence is the limiting
factor in reliable free-space optical communication link performance.
In particular, the problem in guiding the light beam to the SMF is thatthe fluctuation of the atmospheric fluctuation : Scintillation
42

Problem when guiding the light beam to the SMF
Received power

Transmit power

Time

Beam wander

T
T

T

Scintillation (intensity fluctuations)T

Combined effect In general, atmospheric fluctuations are refracted and change the direction of
travel when passing through the boundary of air masses with slightly different
densities. (ex. heat haze or blinking of stars).
 Beam wander: a phenomenon when the direction of optical beam changes
when relatively macroscopic air mass is passed. Daily, Seasonal variation.
 Scintillation or intensity fluctuation : a phenomenon that the received powerfluctuates at short cycles (1-10ms) when the light beam propagates in theatmosphere. (the particle diameter is smaller than the beam diameter and it
becomes active when the temperature is high and the humidity is high)43Scintillation
Distortion of wavefront

Turbulent flow cecellellfilterAndrews Larry.C., Phillips R.L.,
Cynthia Y. Hopen;“Laser Beam Scintillation
With Applications”

Detection system

Ex:Change of beam pattern by scintillation
Relative powerreceived

1.0

0ms

66ms

33ms

After 1km transmission, 100 mm radius lens, λ=800nm

0.5

0 0

0.5

Time (sec)

1.0
44

6HQVLQJ0HFKDQLVPBeam divergence, θ
FSO antenna

FSO antenna

Transmitterwide beam (5m/1km)

Transmitter
Receivernarrow beam (10cm/1 km)

ReceiverPD

SMF

Ip1= Ip2

Po1 䠚 Po2
10μm

500μm

Direct coupling FSO system

Conventional system

 To mitigate atmospheric effects Tracking system is required
45

PD: Photodiode (Si, InGaAs; SMF: Single Mode FiberEvaluation of atmospheric turbulence Cn2 is refractive index structure constant, used to indicate atmospheric turbulence strength>I  I @2
 σ 2 : scintillation index (Normalized intensity variance)
2

VI

I

 strong:>I  I @C n2

5㽢10-14 ≤ Cn2

I

2

2

1.23Cn k 7 / 6 L11 / 6(Rytov variance)2

 moderate: 10-14 ≤ Cn2 ≤ 5㽢10-14>/(1.23 u (2S / O ) 7 / 6 u L11 / 6 u 1  1.06 u D 2 2S /(O u 4l )@

7 / 6

Cn2 in in summer and winter3

Intensity (V)I

10-15≤ Cn2 <10-14

 Weak :VI2

2

Time: 6:04 am, Temp: 28.4 0 C
2Strong

1
0

1000

2000

3000

Intensity (V)3Moderate

Time: 13:04 pm, Temp: 38.8 0 C
2
1
0

0

1000

2000

Weak

3000

Intensity (V)3Time: 20:04 pm, Temp: 32.2 0 C

2.5
2
1.5
1
0.5

0

0.5

1

1.5

2

Time (msec)

2.5

3
4

x 10

Intensity change at different times of fine weather

Strong: at noon of fine day
Weak: sunrise, sunset, rainy days

46

10Gbps Transmission 
10Gbps BERT 2006 January 26-27
Bit Error Rate

Sync Loss Sec.

Power
0

1.0E+00-10

1.0E-02
1.0E-03
1.0E-04-20

BER

1.0E-05-30

1.0E-06
1.0E-07-40

1.0E-08

Rec. Power [dBm]1.0E-01

1.0E-09
1.0E-101.0E-11
1.0E-12

18:00

20:00

22:00

0:00

2:00

4:00

6:00

Time
47

)

WDM Experiment setup and results
Four channel 1550 nm data link operating at 2.5 Gbps WDM
WDM received signal spectrum

BER and received power characteristics

101549.3 1550.1 1550.9 1551.7
nm
nm
nm
nm

10

Log(BER)ITU Grid 100GHz spacing

10
10
10

0

-2

-10

-4

-20

-6

-30

-8

-40

-10

(Error free)
100Date: 23 ~ 24 November 2005

-12

1550.1 nm BER
1550.9 nm BER
Received power

18:00

-50

21:00

-60
03:00

24:00
Time

 2.5 Gbps X 4 channels with output power 100mW/wavelength Stable communication was achieved with no fluctuation orinterference between wavelengths (an output power of 100 mW
per wavelength )48

RoFSO Movie image transmission result
Digital TV broadcasting signal transmission

10

11 December 2008

0

0

-2

-5
Error correction limit

BER

10

10

10

10



-4

-6

-10

-15

-8

-10

0:00

-20

BER Layer A
BER Layer B
Received power (dBm)
03:00

06:00

09:00

12:00

Time

15:00

18:00

21:00

Received power (dBm)

10

A-Layer 1seg video

-25
24:00

Digital TV broadcasting BER and received opticalpower characteristics.
%(5VKRZQKHUHLVFDOFXODWHGIURPHUURUFRUUHFWLRQLQIRUPDWLRQ
7KHHUURUUDWHFXUUHQWO\GLVSOD\HGLVEHWZHHQIRUDQHUURUFRUUHFWLRQZLWKD56DQG9LWHUELFRUG(UURUFROOHFWLRQOLPLWLV

B-Layer 12-segment video 49

Received Power (dBm)

10

8OWUD+LJK6SHHG)627UDQVPLVVLRQ([SHULPHQW
1.28Tbit/s Transmission &153LVD,WDO\WK6HSW
8-O/32- O
DFBs

PCs

EDFA1
(Booster) OC1

..
.
AWG
PD

OA

 32x40Gbps error-free transmission for morethan one hour under the daylight condition

40 Gbps
PRBS (231-1)

Terminal 1

Patchcord
to roof(20 m)I
M

EDFA3 OAEDFA2Terminal 2OC2)62OLQN P 

Loopback

OTBF

data recovery

Institute of Communication, Information and Perception Technologies (TeCIP),
Scuola Superiore Sant’Anna (SSS), Pisa Italy
Achieved 1.28 Tera bits per second world record transmission for a wireless system using a system based a similar concept.
E. Ciaramella, Y. Arimoto, G.Contestable, M. Presi, A. D’ Errico, V. Guanno, and M. Matsumoto, ” 1.28 Terabit/s (32x40 Gbit/s) WDM
50
Transmission System for Free Space Optical Communications,” IEEE Journal Areas in Com. vol. 27, no. 9, Dec. 2009.

Mitigation techniques by present system• We adopted adaptive optics to compensate the influence of lightpropagating in the atmosphere in real time. In particular, we adopted an
optical axis control method using ultra-compact, biaxial, galvano mirror
with fast response.
• The internal angle control is performed by monitoring the deflection angle
by two-dimensional driving, and it operates stably up to 2 kHz in both
azimuth (Az) and elevation (El) directions.
Fiber Coupling

FPM

51

䣈䣕䣑䢢䣖䣴䣣䣥䣭䣫䣰䣩䢢䣵䣻䣵䣶䣧䣯䢢䣇䣸䣱䣮䣷䣶䣫䣱䣰䢢
1. Conventional System• O/E/O conversion
Opticalfiber• Received by Large PD• Rough tracking by beacon
signalPD
LD

Optical Fiber
Input/Output

Bidirectional FSO
communication

PD

Elec.Sig.
LD

Elec.Sig. LD
LD

Lens

PD

2. New developed system:
Ultra-compact moving coil typegalvanometer mirror actuator• No O/E/E conversion• Received by Fiber core
• Rough tracking by
beacon signal

Optical Transceiver

Optical TransceiverHigh Speed Mirror

Lens

Lens

Lens

Opticalfiber

PDHigh Speed Mirror

PID

PID
Bidirectional FSO
communication

QPD

BS

QPD

BS
BeaconFP

Optical Fiber
Input/Output

FP

52

FSO Terminal Evolution-2
3. Future system using closed loop voice coil actuator
Fine Tracking
VCM
Opt. Fiber

Info. Sig.

Opt.Fiber
Cont.
sig

VCM having the function of
converting electric energy into
kinetic energy with a magnetic
field as a medium

Magnet
Coil

BS

BS

Fine
Tracking
VCM

Opt. Fiber

Lens
Info. sig.

PID

QPD

Cont. Sig
Opt.Fiber

Lens

QPD

PID

Hall sensor
Connecter

1. Development of eye-safe laser region Light wavelength: 1550 nm (1 wavelength)· Beacon light: 800-900nm unnecessary
2. Reduction in tracking servo technology, reduction in size, improvement in accuracy· Sensor: GPS, direction sensor, gyro
· Control: VCM
53

Conclusion in FSO
1) We developed an FSO system which uses narrow beam transmission withdirect coupling to the SMF fiber core and without performing O/E andE/O conversion, which make the communication link bandwidth andprotocol transparent. Using technologies such as WDM and EDFA, highdata rate in the order of several Gbps was demonstrated.
2) Evaluating the received optical power level and the propagation link quality
for a continuous period of more than one year, the operating data rate
exceeding 1.5 Gbps was demonstrated at a distance of 1-km with thelink availability above 99.9%.
3) In the absence of severe weather conditions such as atmospheric turbulence,
heavy rain, thick fog, snow and storm, the ISDB-T and W-CDMA signals
were transmitted using the FSO system and good performance wasachieved.
4) The obtained results confirm the technical feasibility and practicality ofutilizing the FSO system as a universal platform for providing 5G
wireless services.
54

Further Study
1) Development of a high-speed communication system
between satellite stations, satellites, aircraft, railroads,
ships and ground stations.
2) Realize a simple, inexpensive, robust FSO system
and aim to spread FSO.
3) Consideration of standardization accompanying
increase of multiple standards.
4) Further experiments are needed to gather data forstatistical analysis of system performance under
different weather conditions.
5) Building Initial Setting Free, Eye safe
55

OVERVIEW FOR OPTICAL WIRELESSCOMMUNICATION

Thank you for your attention

56