Post on 29-Jun-2018
KEYWORDS: LD, LED, FSO, VLC, IrDA, RoFSO.
OVERVIEW FOR OPTICAL WIRELESS COMMUNICATION
16 December 2017
Mitsuji Matsumoto
Waseda University, Japan mmatsumoto@waseda.jp
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.
Wireless technology (Radio/Optical) is promising to solve these challenges. • 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,
BER 0.01%/2,500km has been required and the value of the call loss rate is close to the (3%) of the whole communication network or mobile phone.
• Conventional optical wireless communication has been used as a complementary.
• Areas where best effort communication, or standards can be relaxed.
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
UWB
10 Gbps
1 Gbps
100 Mbps
10 Mbps
1 Mbps
100 Kbps
1 km 100 m
WiMAX
10 m 10 km 1 m
Bluetooth
ZigBee
WLAN a/b/g
Optical fiber communication
Communication distance
Personal Area Comm.
Optical WLAN
IrDA
Long distance communication
Data rate
100 km
3Gbps Visible light communications Fraunhofer, HHI
1.28Tbps FSO by Sss’a, NICT, Waseda
150Mbps VLC- Li-Fi LAN Fudan
LII or )(exp
VLC- IrDA
5-10Gbps IR Fraunhofer
Near Field Comm.
FSO
ps
Mbps
Mbps
bps
ZigBee
IrDA
UWB
B
OpticalWLAN
3Gbps VcommunFraunhofe
1L
VLC-IrDA
5-10Gbps IRFraunhofer
Near FieldCommCommCC
Appearance of Infrared Data Communication Mobile terminal boom in the 1990's: Newton (PDA),Electronic notebook ,Personal Communicator: Start : Windows 95 OS machine
Information exchange and printout with the desktop PC (conventionally cable connection, FD exchange)
Desktop PC
Printer
Mobile PC
Focusing on infrared technology which has been widely used for remote control of home TV, stereo, air conditioner and so on for the past, it is applied for IR communication.
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 from own PDA or cell phone.
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IrDA Roadmap
10Mbps
Single Image Content
Single Music Content
Video / Music Album Contents
SIR
MIR FIR
VFIR Hyper Multimedia Instant Synchronization
UFIR GigaIR
1998 1995 2006 2009 1994
Giga-IR:2009 KDDI,Rohm,Panasonic, W.U., CEC. EG
UFIR:2006 SHARP,WU,NTT, Stanley, EG
HP IBM MS IrSimple 2005 SHARP NTTDocomoITX-EG,Waseda Univ
1Gbps 100Mbps 1Mbps 100kbps
Text base Contents
1998-2004 IrMC/IrFM 2005-2IrMC/IrSimple 2009- Giga-IR
short distance/1m/high speed
9
IrDA/VLC Protocol Stack
OSI 7
OSI 6
OSI 5
OSI 4
OSI 3
OSI 1
OSI 2
IrDA/VLC Physical Layer
IrLAMP
IrSimple
Multimedia Information Broadcast Information
TCP/IP UDP
Internet Session
Protocols OBEXTM
Other Transport Protocols
Other Session
Protocols
l d f
Personal Area Network Applications
upper layers
TinyTP
Inverted 4PPM Manchester Encoding
IR Transmit Circuit
IR receive circuit
Mod.
Dem
LED
UART
Universal Asynchronous Receiver and Transmitter
Infrared circuit diagram
1 frame:10 bits
115.2 kb/s
0 1 0
00 01 10 11
Chip
9.6 kbps - 1.152Mbps
4Mbps(
125
Data bit Pair (DBP)
4PPM Data Symbol(DD)
00 1000 01 0100 10 0010 11 0001
T=500 ns
12
Download Data Activity Time
DDAT(A)
Turn Around Time TAT(A)
Turn Around Time TAT(B)
Data Acknowledge DA(B)
Station A Station B
Download Data Activity Time
DDAT(A)
Dead Time
High efficiency technical challenges
Processing Bitmap info
Decoding Bitmap info
Comparison between early stage IrDA and IrSimple systems
Early stage system in case of 4Mbps
IrSimple system In case of 4Mbps
Approx. 6 sec
Approx. 1 sec 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
Maturity
IrDA Bluetooth
1995
1997
Mid-1998
2001 Mid-2003
Peak of Inflated Expectations - IR
Slope of Enlightenment
Technology Trigger - IR
Plateau of Productivity
Peak of Inflated Expectations - BT
Trough of Disillusionment
Source: Gartner Group / IrDA
‘Intersection of Reality’
10
100
1000
115kbps:SIR
Transfer Speed(Mbps)
GigaIR
UFIR,IrBurst (Diffusion LD)
LD
16Mbps:VFIR
4Mbps:FIR
Diffusion LD
1
VLC
Product technology roadmap IrDA)
Audio
White LED
16
Development of Eye Safe Laser Diode
•the spot size:1000 times •measured beam diameter:4mm •100Mbps/1m
Same Approach is possible for miniature IrDA Unit
Source Size of >2mm will be possible with optimized lens
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
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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
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Blue LED chip
PN
White light
PN junction
Transparent epoxy resin
Emission
Anode+ Cathode-
LED (semiconductor element emitting)
Visible light wavelength
Definition : Electromagnetic waves of wavelength 380-780 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.
Visible Light Communication (VLC)
Light emitting method of white LED
Blue LED+ Yellow phosphor Complementary color
White with one-chip LED with blue/green color mixture
White by combination of red / green / blue LED
10
White light emission White light emission White light emission
Blue LED Ye
llow
ph
osph
or
BG mix. R G B
Origin of visible light wireless communication
A.G.Bell’s Photohone (1880)
Visible Light Transmitter Visible Light Receiver
23
Voice Input
Sun Light
Voice Input
Voice Output
Sun Light
Lens
Lens
glass
Reflector
Parabolic mirror
Selenium
VLC characteristics Emits electromagnetic waves focusing on single wavelength with specific photons. Ease of directivity control Luminous efficiency 30 - 100 (lm / W) Regular light spectrum Fast response to current (short-time strobe lighting)
Communication possible Light amplitude / intensity (light and dark) Optical wavelength (color) Optical phase (shape)
Optical accesspoint
A modulation scheme effective for illumination optical communication
Basic requirement • 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]
slot Turn On
off
slot
25
on
off
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 in
signal quantity) 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 of single and two-dimensional elements
Sa
1 1
SG2(noise source)
Ss
20
• 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 high Fast communication is difficult;
• Flicker occurs at low speed (frame rate is several tens of kHz).
Single PD light receiving surface Ss
SG2(noise source)
Spatial light interference range
Image sensor receiving surface Sa
• Easy structure, high speed operation by element;
• It is weak against influence of background light noise due to surface light reception, making it difficult to communicate over long distances.
Optical Wireless LAN (Omnidirectional system structure)
Access the Internet source) Receiving PLC modem
LED lighting fixture
Down VLC Up IR
Dongle Transmitting PLC modem
PC or Internet
Wi-Fi and Li-Fi
(a) Wi-Fi
Radio wave
Wireless LAN card
Access-point
Light wave
Optical Accesspoint (LED lighting) Ethernet
Optical wireless dongle (b) Li-Fi
Client
Ethernet
Client
Omnidirectional
Challenges Master unit Master unit
Shared space Shared space T1 T1 T2 T2
VLC VLC VLC VLC
Principle of spatial light CSMA / CD (CA):
IEEE 802.3 CSMA/CD (CA): carrier sense multiple access with collision detection/avoidance
(a) no collision (b) collision
Collision Detect
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 light and radio waves, attenuation is small and it can be transmitted far away
Damping due to absorption / scattering / light shielding, short distance (average about 15 - 100 m)
speed There is a speed limit. Faster than in air (average about 1500 m / s)
Speed depends on water pressure and water temperature
Sound velocity minimum around 1000 m (approx. 1470 m / s)
capacity The amount of information that can be transmitted with as low frequency as possible is small
Large capacity (easy to control due to visibility)
For seawater and freshwater, fresh water has longer propagation distance at any frequency
Frequency Characteristic in under sea
500 1500 2000 0.0
0.5
1.0 Bay area 450nm
550nm 650nm
1000 Distances (cm)
2000 4000 6000 8000 10000 0.0
0
0.5
1.0
Inte
nsiti
es (a
.u.)
Distilled Water
Abso
rptio
n at
tenu
atio
n
Electro magnetic MW
IR
UV
X-ray VLC
Underwater sonic
Frequency (Hz)
Spectral decay of transmission distance by extinction coefficient
Attenuation of electromagnetic waves (Radio wave/Light) and sound waves in seawater
F/Fo e-cL C(Extinction co.) a(Absorption co.) 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
Submarine station Max Comm. Distance:100m Speed 1Mbps TWA
Marine environment visible light wireless communication system
Wav
elen
gth
sele
ctiv
e
adap
tatio
n
Data Data
Wavelength selective optical filter
Receiver Transmitter
Underwater Light
PD
Seawater
Lighting & Carrier by White light
1000 times/6500m
Adaptive measures for marine environment
"Shinkai 6500" is a submersible survey ship capable of dive to 6,500 m in depth (1989) -JAMSTEC
1200 times/ 6500m/ 3 person
doc.: IEEE 802.11-17/0962r2
Specialty Areas (Low Volumes)
Mass Market (Very High Volumes)
Very Low Data rates (simple protocols )
The IEEE 802 OWC standards Very High Data rates (complex protocols )
Optical Camera Communications in
802.15.7m - Limited MAC relevance
eas
(complex pro
802.15.13 - MAC based on
802.15
802.15.7- 2011
Mass Marke
ols )
Potential LC for 802.11 - MAC based on 802.11
Submission Slide 36 Nikola Serafimovski (pureLiFi)
Reference:An overview on high speed optical wireless/light communications
OWC/LC WiFi area
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 Wireless Communications suitable for speciality wireless networks Problem Neither 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
July 2017
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 Slide 38 Nikola Serafimovski (pureLiFi)
Depending on the deployment scenario and application, 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 Application scenarios
FSO
FTTH
39 999993999
Mountainous terrain
Backhaul (~5 km)
RoFSO transceiver remote base station Metro network
extension
Remote located settlements
RoFSO link Optical fiber link RF based links RoFSO transceiver
No fiber connectivity
Internet
1550nm 1550nm
Transmitting Terminal
Receiving Terminal
Opt. Beam
Optical fiber Optical fiber
Atmospheric turbulence
How to realize Ultra High Speed and Reliable Optical Link through the atmosphere, based on the compatibility with existing fiber infrastructure using 1550 nm wavelength
What are the challenges of FSO?
40
Direct coupling high-speed FSO system
• No O/E & E/O conversion • Uses 1550nm wavelength • Compatibility with existing fiber infrastructure. • Protocol and data rate independent. Seamless connection of space
and optical fiber. • broad bandwidth (InGaAs) and no power limitations • Tracking control mechanism
Provide high speed physical transmission path and services equivalent to optical fiber.
By Direct coupling between optical fiber and free-space
10μm
1550nm
Transmitting Module
Receiving Module
Opt. Beam
Optical fiber Optical fiber
Atmospheric Turbulence
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 of temperature and pressure, etc.
Among them, effects of fog and turbulence are severe. However, in the case of fog, we can overcome by some way for example increase transmission 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 that the fluctuation of the atmospheric fluctuation : Scintillation
42
Beam wander
Scintillation (intensity fluctuations)
Time
Transmit power Received power
Combined effect T
T
T
T
Problem when guiding the light beam to the SMF
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 power fluctuates at short cycles (1-10ms) when the light beam propagates in the atmosphere. (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
Turbulent flow cellTurbulent flow ce ell
Distortion of wavefront
Detection system
filter
After 1km transmission, 100 mm radius lens, λ=800nm 0ms 33ms 66ms
Ex:Change of beam pattern by scintillation
Time (sec) R
elat
ive
pow
er
rece
ived
0 0.5 1.0 0
0.5
1.0
Andrews Larry.C., Phillips R.L., Cynthia Y. Hopen; “Laser Beam Scintillation With Applications”
44
Po1 Po2
PD
500μm
Conventional system
Ip1= Ip2
To mitigate atmospheric effects Tracking system is required
SMF
10μm
Direct coupling FSO system
FSO antenna
Transmitter Receiver wide beam (5m/1km)
Beam divergence, θ
FSO antenna
Transmitter Receiver narrow beam (10cm/1 km)
PD: Photodiode (Si, InGaAs; SMF: Single Mode Fiber 45
0 1000 2000 3000
1
2
3
Inten
sity (
V)
0 1000 2000 30000
1
2
3
Inten
sity (
V)
0 0.5 1 1.5 2 2.5 3
x 104
0.5
1
1.5
2
2.5
3
Time (msec)
Inten
sity (
V)
Time: 6:04 am, Temp: 28.4 0 C
Time: 13:04 pm, Temp: 38.8 0 C
Time: 20:04 pm, Temp: 32.2 0 C
Intensity change at different times of fine weather
Cn2 in in summer and winter
Evaluation of atmospheric turbulence
46
Strong
Weak
Moderate
Cn2 is refractive index structure constant, used to indicate atmospheric turbulence strength
σI2 : scintillation index (Normalized intensity variance)
Weak : 10-15≤ Cn2 <10-14
moderate: 10-14 ≤ Cn2 ≤ 5 10-14
strong: 5 10-14 ≤ Cn2
2
2
2
I
III
6/116/722 23.1 LkCnI
(Rytov variance)
Strong: at noon of fine day Weak: sunrise, sunset, rainy days
))4/(206.11)/2(23.1/( 6/726/116/72
2
2 lDLI
IICn
10Gbps Transmission
10Gbps BERT 2006 January 26-27
1.0E-12
1.0E-11
1.0E-10
1.0E-09
1.0E-08
1.0E-07
1.0E-06
1.0E-05
1.0E-04
1.0E-03
1.0E-02
1.0E-01
1.0E+00
18:00 20:00 22:00 0:00 2:00 4:00 6:00
Time
BER
Bit Error Rate Sync Loss Sec. Power
Rec.
Pow
er [d
Bm]
0
-10
-20
-30
-40
47
Four channel 1550 nm data link operating at 2.5 Gbps WDM
2.5 Gbps X 4 channels with output power 100mW/wavelength Stable communication was achieved with no fluctuation or interference between wavelengths (an output power of 100 mW per wavelength )
WDM received signal spectrum BER and received power characteristics
18:00 21:00 24:00 03:0010
-12
10-10
10-8
10-6
10-4
10-2
100
Time
-60
-50
-40
-30
-20
-10
0
1550.1 nm BER1550.9 nm BERReceived power
Date: 23 ~ 24 November 2005
Rec
eive
d P
ower
(dB
m)
Log(
BE
R)
(Error free)
WDM Experiment setup and results
1549.3 nm
1550.1 nm
1550.9 nm
1551.7 nm
ITU Grid 100GHz spacing
48
Digital TV broadcasting BER and received optical power characteristics.
RoFSO Movie image transmission result
Digital TV broadcasting signal transmission
0:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:0010-10
10-8
10-6
10-4
10-2
100
BER
11 December 2008
Time
BER Layer ABER Layer BReceived power (dBm)
0:00 03:00 06:00 09:00 12:00 15:00 18:00 21:00 24:00-25
-20
-15
-10
-5
0
Rec
eive
d po
wer
(dB
m)Error correction limit
A-Layer 1seg video
B-Layer 12-segment video
49
8- /32- DFBs
EDFA1 (Booster)
AWG
. . .
PCs
40 Gbps PRBS (231-1)
IM
data recovery
OC1 Terminal 1
OTBF
EDFA2
EDFA3 PD OA OA
OC2
Loopback
Patchcord to roof (20 m)
1.28Tbit/s Transmission
32x40Gbps error-free transmission for more than one hour under the daylight condition
Terminal 2
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 Transmission System for Free Space Optical Communications,” IEEE Journal Areas in Com. vol. 27, no. 9, Dec. 2009. 50
Institute of Communication, Information and Perception Technologies (TeCIP), Scuola Superiore Sant’Anna (SSS), Pisa Italy
Mitigation techniques by present system
Fiber Coupling
FPM
51
• We adopted adaptive optics to compensate the influence of light propagating 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.
Optical Transceiver
Optical fiber
LD
LD
PD LD
LD
PD
PD PD Lens
Optical Transceiver
Elec.Sig. Elec.Sig.
Lens
Bidirectional FSO communication
BS BS
FP FP
Beacon
QPD QPD
PID PID
High Speed Mirror High Speed Mirror Lens Lens
Bidirectional FSO communication
Optical Fiber Input/Output
Optical Fiber Input/Output
2. New developed system: Ultra-compact moving coil type galvanometer mirror actuator
1. Conventional System
Optical fiber
52
• O/E/O conversion • Received by Large PD • Rough tracking by beacon signal
• No O/E/E conversion • Received by Fiber core • Rough tracking by beacon signal
QPD
QPD PID Fine
Tracking VCM
Fine Tracking VCM
Opt. Fiber
Opt. Fiber Opt.Fiber
BS
BS
Lens
Lens
Cont. sig
Cont. Sig
Info. Sig.
Info. sig.
Opt.Fiber
PID
VCM having the function of converting electric energy into kinetic energy with a magnetic field as a medium
3. Future system using closed loop voice coil actuator
Magnet Coil
Connecter Hall sensor
FSO Terminal Evolution-2
53
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
1) We developed an FSO system which uses narrow beam transmission with direct coupling to the SMF fiber core and without performing O/E and E/O conversion, which make the communication link bandwidth and protocol transparent. Using technologies such as WDM and EDFA, high data 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 the link 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 was achieved.
4) The obtained results confirm the technical feasibility and practicality of utilizing the FSO system as a universal platform for providing 5G wireless services.
Conclusion in FSO
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 for statistical analysis of system performance under different weather conditions.
5) Building Initial Setting Free, Eye safe
55
OVERVIEW FOR OPTICAL WIRELESS COMMUNICATION
Thank you for your attention
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