Transcript Communications Engineering

EN554 Photonic Networks
Lecture 1: Introduction
Professor Z Ghassemlooy
Northumbria Communications Laboratory
School of Informatics, Engineering and
Technology
The University of Northumbria
U.K.
http://soe.unn.ac.uk/ocr
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Contents
 Reading List
 Lecture 1: Introduction
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Transmission Media
History
Communication Technologies
Applications
System
Challenges Ahead
Lecture 2: Components for Photonic Networks
Lecture 3: Optical Amplifier
Lecture 4: System Limitation and Non-linear effect
Lecture 5: Transmission System Engineering Part 1
Lecture 6: Transmission System Engineering Part 2
Lecture 7: Photonic Networks
Lecture 8: Photonic Switching
Lecture 9: Wavelength Routing Networks Part 1
Lecture 10: Wavelength Routing Networks Part 2
Lecture 11: Access Network
Lecture 12: Revision
Tutorials and Solutions: Visit http://soe.unn.ac.uk/ocr
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Reading List
 Essential Reading List
– lyas, Mohammad and Mouftah, Hussien: The Handbook of Optical
Communication Networks, CRC Press, 2004, ISBN 0-84-931333-3
– Ramasawami, R and Sivarajan, K.N: Optical network: A practical
perspective, Morgan Kaufmann, 2001, ISBN 1-55-860655-6
– Donati, Silvano: Photodetectors: Devices, Circuits and
Applications, Prentice Hall, 2000, ISBN 0-13-020337-8
 Optional Reading List
– Stern, T.E. and Bala, K: Multiwavelength Optical Networks: A
layered approach, Addison Wesley, 1999, ISBN 0-20-130967-X
– Sabella, R and Lugli, P:High speed optical communications,
Kluwer Academic, 1999, ISBN 0-41-280220-1
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Transmission Media
 Transmission Medium, or channel, is the actual physical
path that data follows from the transmitter to the receiver.
 Copper cable is the oldest, cheapest, and the most
common form of transmission medium to date.
 Optical Fiber is being used increasingly for high-speed
applications.
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Transmission by Light: why?
Growing demand for faster and more efficient
communication systems
Internet traffic is tripling each year
It enables the provision of Ultra-high bandwidth to
meet the growing demand
Increased transmission length
Improved performance
etc.
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Demand for Bandwidth
Bandwidth
Demand
1990
2000
2010
Typical data bandwidth requirement
• Raw text = 0.0017 Mb
• Word document = 0.023 Mb
• Word document with picture = 0.12 Mb
20,000 x • Radio-quality sound = 0.43 Mb
• Low-grade desktop video = 2.6 Mb
• CD-quality sound = 17 Mb
• Good compressed (MPEG1) video = 38 Mb
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Historical Developments
• 800 BC
• 400 BC
• 150 BC
• 1880
Use of fire signal by the Greeks
Fire relay technique to increase transmission distance
Encoded message
Invention of the photophone by Alexander Graham Bell
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Historical Developments - contd.
• 1930
• 1950-55
• 1962
• 1960
Experiments with silica fibres, by Lamb (Germany)
The birth of clad optical fibre, Kapany et al (USA)
The semiconductor laser, by Natan, Holynal et al (USA)
Line of sight optical transmission using laser:
- Beam diameter: 5 m
- Temperature change will effect the laser beam
Therefore, not a viable option
•1966- A paper by C K Kao and Hockham (UL) was a break
through
- Loss < 20 dB/km 
- Glass fibre rather than crystal (because of high viscosity)
- Strength: 14000 kg /m2.
Contd.
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Historical Developments - contd.
• 1970 Low attenuation fibre, by Apron and Keck (USA) from 1000
dB/km - to - 20 dB/km
- Dopent added to the silica to in/decrease fibre refractive index.
• Late 1976 Japan, Graded index multi-mode fibre
- Bandwidth: 20 GHz, but only 2 GHz/km
Start of fibre deployment.
• 1976 800 nm Graded multimode fibre @ 2 Gbps/km.
• 1980’s
- 1300 nm Single mode fibre @ 100 Gbps/km
- 1500 nm Single mode fibre @ 1000 Gbps/km
- Erbium Doped Fibre Amplifier
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Historical Developments - contd.
• 1990’s
- Soliton transmission (exp.): 10 Gbps over 106 km with no error
- Optical amplifiers
- Wavelength division multiplexing,
- Optical time division multiplexing (experimental) OTDM
• 2000 and beyond
- Optical Networking
- Dense WDM, @ 40 Gbps/channel, 10 channels
- Hybrid DWDM/OTDM
 ~ 50 THz transmission window
 > 1000 Channels WDM
 > 100 Gbps OTDM
 Polarisation multiplexing
- Intelligent networks
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Lightwave Evolution
*
10,000
Systems
Research
Experiments
3000
1000
*
Capacity (Gb/s)
300
100
30
10
3
1
0.3
0.1
*
0.03
80
82
84
86
88
90
Single Channel (ETDM)
Multi-Channel (WDM)
Single Channel (OTDM)
WDM + OTDM
WDM + Polarization Mux
Soliton WDM
92
94
96
Year
Prof.
Z Ghassemlooy
98
00
02
04
Courtesy:
A. Chraplyvy
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System Evolution
10000
Capacity (Gb/s)
1000
100
Optical networking
Wavelength Switching
TOTDM
Research Systems
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Commercial Systems
1
Fiberization
Digitization
SONET rings and
DWDM linear
systems
0.1
1985
1990
1995
Year
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2000
2004
cisco
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Existing Systems - 1.2 Tbps WDM
DWDM
• Typical bit rate 40 Gbps / channel
• ~ 8 THz (or 60 nm) Amplifier bandwidth
• 32 channels (commercial) with 0.4 nm (50 GHz) spacing
• 2400 km, no regeneration (Alcatel)
Total bandwidth = (Number of channels) x (bit-rate/channel)
OTDM
• Typical bit rate 6.3 Gbps / channel
• ~ 400 Amplifier bandwidth
• 16 channels with 1 ps pulse width
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Commercial Systems
System
Year
WDM
chan nels
FT3
1980
1
FTG -1.7
1987
1
FT -2000
1992
1
NGLN
1995
8
1999
80
40
2001
160
10 Gb/s
1.6 Tb/s
20,640,000
640 km
2003
128
64
10 Gb/s
40 Gb/s
1.28 Tb/s
2.56 Tb/s
16,512,000
33,0 24,000
4000 km
1000 km
WaveStar
400G
TM
WaveStar
1.6T
TM
LambdaXtreme
Voice
channels
per fibre
Bit rate/
channel
Bit rate/
Fibre
45 Mb/s
45 Mb/s
672
7 km
1.7 Gb/s
24,192
50 km
2.5 Gb/s
32,256
50 km
20 Gb/s
258,000
360 km
200 Gb/s
400 Gb/s
2,580,000
5,160,000
640 km
640 km
1.7
Gb/s
2.5
Gb/s
2.5
Gb/s
2.5
Gb/s
10 Gb/s
Regen
spans
H. Kogelnik, ECOC 2004
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Communications Technologies
Year
Service
Bandwidth distance product
1900
Open wire telegraph
500 Hz-km
1940
Coaxial cable
60 kHz-km
1950
Microwave
400 kHz-km
1976
Optical fibre
1993
700 MHz-km
Erbium doped fibre amplifier
1 GHz-km
1998
EDFA + DWDM
> 20 GHz-km
2001-
EDFA + DWDM
> 80 GHz-km
2001-
OTDM
> 100 GHz-km
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Optical Technology - Advantages
• High data rate, low transmission loss and low bit error rates
• High immunity from electromagnetic interference
• Bi-directional signal transmission
• High temperature capability, and high reliability
• Avoidance of ground loop
• Electrical isolation
• Signal security
• Small size, light weight, and stronger
62 mm
21mm
648 optical fibres
363 kg/km
448 copper pairs
5500 kg/km
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Applications
Electronics and Computers
 Broad Optoelectronic
 Medical Application
 Instrumentation
 Optical Communication Systems
 High Speed Long Haul Networks 
(Challenges are transmission type)
 Metropolitan Area Network (MAN) ?
 Access Network (AN)?
Challenges are:
- Protocol
- Multi-service capability
- Cost
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Undersea Cables
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System Block Diagram
Photonics Institute
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Source
Source
coding
Modulation
• Analogue
• Digital
Multiplexing
Modulation
• Frequency
• Time
External
Internal
• Pulse shaping
• Channel coding
• Encryption
• etc.
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Receiver
1st-stage
amplifier
2nd-stage
amplifier
Pre-detection
filtering
Sampler
&
detector
Demultiplexer
• Equalizer
Demodulator
Decoder
Decryption
Output signal
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All Optical Network
IP
ATM
IP
SDH
ATM
SDH
SDH
ATM
IP
Other
Open Optical Interface
All Optical Networks
Challenges ahead:
• Network protection
• Network routing
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• True IP-over-optics
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Challenges Ahead
 Modulation and detection and associated high speed electronics
 Multiplexer and demultiplexer
 Fibre impairments:
. Loss
. Chromatic dispersion
. Polarization mode dispersion
. Optical non-linearity
. etc.
 Optical amplifier
. Low noise
. High power
. Wide bandwidth
. Longer wavelength band S
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Challenges Ahead - contd.
 Dedicated active and passive components
 Optical switches
 All optical regenerators
 Network protection
 Instrumentation to monitor QoS
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Chromatic Dispersion
• It causes pulse distortion, pulse "smearing"
effects
• Higher bit-rates and shorter pulses are less
robust to Chromatic Dispersion
• Limits "how fast“ and “how far” data can travel
10 Gbps
60 Km SMF-28
t
40 Gbps
cisco
4 Km SMF-28
t
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Dispersion Compensating Fibre
By joining fibres with CD of
opposite signs (polarity) and
suitable lengths an average
dispersion close to zero can be
obtained; the compensating
fiber can be several kilometers
and the reel can be inserted at
any point in the link, at the
receiver or at the transmitter
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Polarization Mode Dispersion (PMD)
Ey
nx
Ex
ny
Input pulse
Spreaded output pulse
The optical pulse tends to broaden as it travels down the
fibre; this is a much weaker phenomenon than chromatic
dispersion and it is of some relevance at bit rates of 10Gb/s
or more
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Combating PMD
Factors contributing to PMD
–
–
–
–
–
Bit Rate
Fiber core symmetry
Environmental factors
Bends/stress in fiber
Imperfections in fiber
Solutions for PMD
– Improved fibers
– Regeneration
– Follow manufacturer’s recommended installation
techniques for the fiber cable
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Optical Transport Network
< 10000 km
< 10 Tbit/s
Global Network
Wide Area
Network
< 100 km
< 1 Tbit/s
Metropolitan/Regional
Area Optical Network
Client/Access
Networks
FTTB
Cable modem
Networks
SDH/
SONET
ISP
ATM
Gigabit
Ethernet
< 20 km
100M - 10 Gbit/s
ATM
FTTH
Courtesy: A.M.J. Koonen
Cable
PSTN/IP
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Mobile
Corporate/
Enterprise Clients
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