Insurers' journeys to build a mastery in the IoT usage
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Asee05
1. Demonstration of Optical Orthogonal
Frequency Division Multiplexing
Dr. Ali Setoodehnia1
Dr. Feng Huang1
Dr. Hong Li 2
Dr. Kamal Shahrabi1
email: asetoode@kean.edu
1. Technology Department, Kean University, US
2. College of Technology, CUNY, Brooklyn, NY
2. Outline
1.
Overview of Carriers
2.
Introduction to OFDM
3.
Introduction to various realizations.
4.
The possible realization and the proposed optical OFDM.
5.
Why do we want to implement the proposed system
6.
Possible implementations of the pulse shaper, advantageous and
disadvantageous
7.
The proposed system, channel equalization capability and security of
information transmission.
8.
Results
9.
Conclusions, the education perspectives, and things we will like to do
in the future.
3. Overview of carriers
ā¢In a single carrier system, a single fade or interferer can
cause the entire link to fail
ā¢In multi-carrier system, only a small percentage of the
sub-carriers will be affected.
ā¢The total signal frequency band is divided into N nonoverlapping frequency sub-channels. Each sub-channel
is modulated with a separate symbol and then the N subchannels are frequency-multiplexed.
ā¢Good to avoid spectral overlap of channels to eliminate
inter-channel interference. However, this requires guard
band which leads to inefficient use of the available
spectrum.
4. OFDM
Using the overlapping multi-carrier
modulation technique, we save more of the
bandwidth.
To realize the overlapping multi-carrier
technique, we need to reduce crosstalk
between sub-carriers, which means that we
want orthogonality between the modulated
carriers.
In OFDM, the carriers are linearly
independent (i.e., orthogonal)
Applying the discrete Fourier transform (DFT)
5. Concept of OFDM
ā¢The OFDM signal, multiplexed in the individual spectra with a
frequency spacing b equal to the transmission speed of each subcarrier
ā¢At the center frequency of each sub-carrier, there is no crosstalks
from other channels. Therefore, if we use DFT at the receiver and
calculate correlation values with the center of frequency of each
sub-carrier, we recover the transmitted data with no crosstalk.
6. Concept of OFDM
Each subcarrier has exactly an integer
number of cycles in the interval T, and the
number of cycles between adjacent
subcarriers differs by exactly one. This
property accounts for the orthogonality
between the subcarriers
7. Introduction to OFDM and optical implementation
Orthogonal Frequency Division Multiplexing and optical
realization.
Why optical OFDM
ļ§ Channel equalization;
ļ§ Extremely large bandwidth (5 THz for 200fs optical pulse)
utilized by 100 MHz RF modulation bandwidth with date
fusion technique (TDM).
Ultrafast pulse shaping techniques
ļ® Ultrafast pulse:
Within the pulse envelop only a few circles of the carrier
wave
ļ® Advantage of pulse shaping:
Arbitrary pulse synthesis; high speed communication,
coherent control etc.
9. Viewing the pulse shaper as a DSP instrument
At (1), the input ultrafast pulse contains the whole
spectrum at the same beam,
(2)
At (2), different colors are spread in spatial domain, the
beam at different location will have less spectrum
component; the corresponding pulse duration is longer.
(1)
(Time to spatial
dispersed
frequency
component)
At (3), combined into the same beam again, if there is
no pattern put into the pulse, it will correspond to the
input pulse; if there are any phase mask to the AOM,
the pulse will spreading depends on the FT of the
pattern imposed on the AOM
(3)
AOM
Modulator
(spatial dispersed
frequency component
to time again)
RF Mixer
FFT
FFT
10. Full use of the capacity of optical fiber capacity
TRAFFIC TYPE
BIT RATE (Mb/s)
Voice
Data
High Fidelity Audio
Teleconferencing
Entertainment Video
0.064
0.01-10
1.0
1.5
50-150
1. Wire Pair 2. Coax Cable
3. Waveguide 4. Single Mode Fiber
LOSS (dB/km)
1
10.0
1.0
0.1
1 MHz
2
3
4
1 GHz
1 THz
BANDWIDTH
ā¢ Hybrid OOFDM/WDM/TDM gives flexible, cost-
effective solution to the opto-electronic bottleneck problem
11. Available Spatial Light Modulators for pulse shaping
Fixed Mask, Holographic, Real-time Holographic
ļ® Phase and Amplitude; no pixels; no wire
LCM-Arrays
ļ® Phase and Amplitude; pixels; multi-line wires
Deformable Mirror
ļ§ Phase; no pixels; multi-line wires
Acousto-optic modulator, best for our application:
higher update rate, high resolution.
Speed of modulation, bandwidth resolution, update rate,
Oriented for different applications.
12. Programmable Pulse Shaping Using Liquid Crystal
Modulator (LCM) Array
ā¢ Same 4f configuration as the AOM pulse shaper
ā¢Using the LCM array, multiple lines attached to the pixels
ā¢Most of time phase only or phase-and-amplitude (using
two sets of 4f system or two sets of LCM arrays.
ā¢Using the liquid crystal to change the polarization of lights
therefore the phase of the input pulse.
ā¢Typically 128 pixels on 100 Āµm centers; up to 512 pixels reported.
ā¢Reprogramming time > 10 ms
ā¢Low attenuation
ā¢Demonstrated to below 10 fs
ā¢Phase and amplitude response must be calibrated
13. Ch
Ch ann
el
Ch ann
1
el
Ch ann
2
el
an
3
ne
l4
Ch
...
an
ne
lN
Wavelength
Chirped Pulse WDM of Bell Labs
Time
Principles: A mode-lock laser
~150 fs, using fiber to stretch
the pulse to ~30 ns and
spectrum is spread in this time
range, using fast EO modulator
(8 GHz) to modulate the
stretched pulse and create
about 300 WDM channels
Advantages: High density
WDM, individual programmable
bandwidth for each WDM
channel
Disadvantages: Strong time
wavelength coupling
14. Programmable Pulse Shapers: Movable and Deformable Mirrors
Using the same optical setup, instead of AOM or LCM, a
Mirror was placed in the center Fourier Plane.
ā¢ Pivoting Mirror provides a linear spectral phase shift, hence
a delay!
ā¢Spectral phase only control
ā¢Reprogramming time ~ 1 msec
ā¢Low attenuation
ā¢Continuous spatial modulation,
15. Array-Waveguide-grating Pulse Shaper
ā¢ A double arrayed waveguide grating with a spatial phase
Filter forms a nearly integrated pulse shaper
ā¢Has been demonstrated for fixed dispersion slope compensation
For 2*40 WDM channels in C and L bands simultaneously.
16. Combine WDM and TDM
Eout (Ļ) = Ein (Ļ) M (Ļ)
Eout (t ) = Ein (t ) ā M (t )
Synthesis of shaped fs
optical pulses through
shaped Āµs RF pulses
Arbitrary spectrum
modulation (both phase
and amplidue offers
possibilities for any
encoding scheme (ASK,
PSK, FSK ...)
High fidelity amplification
achievable using standard
techniques
It is also shown one can propagate the Acoustic wave in parallel
with the light wave.
17. Advantage of Ultrafast Communication
Immunity to EMI
No Cross-Talk Between Wires
Difficult to Tap - High Security
Light Weight and Small Cable Size and
compact system
No Ground-Potential Difference
Currents
18. Optical OFDM communication
Traditional optical point to point communication
ļ® One or a few channels only, low-powered infrared
lasers
AirFiber (Nortel Networks), claims to have a product that, when deployed
throughout a metropolitan area, creates a meshed architecture that can
transmit data in up to four directions at 622 Mbit/s simultaneously in a
distance range between 200 and 450 meters.
TeraBeam Corp (Lucent Technologies Inc.), can be used as a point-tomultipoint product that uses a hub-and-spoke architecture. it can achieve
data rates of 100 Mbit/s. 1-2 Km.
Proposed optical point to point satellite communication
ļ® OFDM functionality: Power equalization, Channel
Add-Drop, etc.
ļ®
A compact system
19. Time
TDMA
A: accessing
WDMA
Channel N
Channel 1
Channel 2
Channel 3
Channel 4
...
Channel N
Channel 1
Channel 2
Channel 3
Channel 4
...
Traditional Multiplexing Methods
Wavelength
Time
WD-OFDM
20. CDMA as the coding scheme-WD-CDMA
Why Wavelength Domain
āOptical Bandwidth(5 THz) v.s. Electronic Speed
(~1GHz)
O/E Interface needs High Ratio (104) Data Compression
Implementation of WD-OFDM
āSpectral Encoder (Spread Time)
Amplitude Only (Optical Codes, PPM)
Phase Only (Binary Codes)
21. Intensity
Wavelength
New Protocol WD-OFDM
Time
Wavelength
Pulse Shaping WDM: hundreds time increase of
Date Transmission rate (DTR) combined with TDM
Pulse Shaping CDM: hundreds time increase of
Channel number combined with TDM
High Spectrum Efficiency
22. Experimental results
1
BER for the proposed transmission
BER for the nomal transmission
Two channel turned off
0.9
S (Ļ ) = ā« S (i )e āiĻt dt
0.7
Bit Error Rate
0.8
N (Ļ ) = ā« N (i )e āiĻt dt
0.6
C (Ļ ) ā¢ ( S (Ļ ) + N (Ļ ))
C (i ) ā ( S (Ļ ) + N (i ))
c(Ļ ) ā ( S (Ļ ) + N (Ļ ))
0.5
0.4
0.3
0.2
0.1
0
0
10
20
30
Channel
40
50
60
23. Experimental results
4
3.5
Bit Error Rate
3
BERX100 for the proposed transmission
BER for normal transmission
channel transmission pattern
2.5
2
1.5
1
0.5
0
0
10
20
30
Channel
40
50
60
24. Conclusions and the following works
Novel techniques like optical OFDM and Pulse Shaping
can achieve 2Tb/s with commercially available components:
Components level
ļ® Introduction to various femtosecond pulse shaping
techniques
ļ® Channel Equalization from OFDM
System level
ļ® Optical OFDM communication and information
transmission
Following work
ļ® Developing demo system for education and external
funding purpose.
25. Applications of AOM spectral encoder
Spectrum phase and amplitude control implemented via diffraction
from a modulated traveling acoustic wave.
Components level
ļ® Channel Equalization
ļ® Tunable Dispersion Compensation
ļ® Adaptive phase feedback
System level
ļ® DWDM/TDM Network