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International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2409
Abstract: In this paper a novel and simple non-return-to-zero
differential phase shift keying (NRZ-DPSK) wavelength
division multiplexing (WDM) system is investigated using
OPTSIM. It has been analyzed Bit Error Rate (BER) and
Q-value performance for WDM system using Differential
Phase Shift Keying (DPSK) modulation scheme. we study the
BER as well as Q-value performance for different system
parameters such as fiber length, gain, number of amplifier and
channel spacing. With the aid of analysis and simulation
results it is demonstrated that the influence of different system
parameters on the BER and Q-value performance of an
Optical system using differential modulation schemes.
Keywords — Optical Communication, WDM, BER, DPSK,
Fiber Length, Q-value, Fiber Gain.
I. INTRODUCTION
The bandwidth-distance product is a figure-of-merit in
optical communication systems. Increase in data-rate per
channel and tighter channel spacing in the main factors to
increase the capacity of optical communication systems.
Tight channel spacing and a 40 Gbps and higher data rate of
a WDM system are the possible solutions.
A WDM system uses the Wavelength Division Multiplexing
technique to communicate the channels with very low
channel spacing so that they do not interfere so much and the
receiver is capable to receive a good quality signal. A WDM
network provides an effective telecommunication
infrastructure over which a verity of services can be
delivered[1].
To improve the quality of the received signal and to
minimize both the linear and the nonlinear impairments over
the transmission fiber, an optimal modulation format is
needed[3]. A modulation format with a narrow optical
spectrum improves the spectral efficiency and tolerance to
chromatic dispersion. A modulation format with constant
optical power can be less susceptible to SPM and XPM[4].
Modulation format with multiple signal levels will carry
more information than binary signals and its longer symbol
duration will reduce the distortion induced by chromatic
dispersion and polarization mode dispersion[11].
Use of low noise optical amplifiers, advanced optical fibers
and forward error correction techniques, are crucial to realize
high spectral efficiency, and hence high-capacity optical
transmission networks. Constant intensity formats like
DPSK and DQPSK, although have relatively complex
transmitter and receiver setups still proved their strong
candidature for high data-rate and spectral efficient DWDM
systems. These constant intensity formats have inherent 3-dB
better receiver sensitivity by using balanced detection[12].
II. SIMULATION TOOL (OPTSIM)
This simulation tool (OPTSIM) provides support for
multiple parameter-scans-based optimizations. It is the only
design tool with multiple engines implementing both the
Time Domain Split Step and the Frequency Domain Split
Step for the most accurate and efficient simulation of any
optical link architecture. MATLAB interface makes it easy to
develop custom user models using the m-file language and/or
the Simulink modeling environment. Interfaces with
laboratory test equipment such as Agilent and Luna to merge
simulation with experiment. Interfaces with device-level
design tools such as Beam PROP and Laser MOD provide a
powerful mixed-level design flow for optoelectronic circuits
and systems. Application Programming Interface (API) for
programming languages such as C/C++ for the development
of custom user models. Best Fit Laser Toolkit™ makes
customizing powerful rate-equation laser model parameters
to fit desired performance characteristics easily. Extensive
library of predefined manufacturer components makes it easy
to model commercially available devices. Intuitive and
flexible measurement post-processing graphical interface
acts like a virtual laboratory instrument.
III. SYSTEM MODEL
Block diagram of a WDM system that is implemented for
simulation is shown in Fig. 1. In this work DPSK transmitter
and receivers are used in a WDM system for Optical fiber
communication. The DPSK transmitter and receiver are first
designed as a compound component and then called in the
schematic.
Fig.1 Shows the Block Diagram of a WDM System
Vandana1, Gitanjali Pandove
2
BER and Q-Value Performance Analysis of
WDM Network Using DPSK Modulation
Format
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2410
Various measurement tools such as Electroscope, BER
estimator and BER calculator can be used to take the
measurement of different performance parameters such as
BER, Q-value etc.
IV. SIMULATION RESULTS
Here simulation results showing BER performance and
Q-value performance of a WDM optical system using DPSK
modulation scheme are presented. In the following
subsections we discuss the effect of three key parameters
along with the transmitter power on BER and Q-value
performances at three channels; channel 1, channel 8 and
channel 16 of a 16-channel WDM system.
A. Effect of Booster Gain
1) BER Performance
From the graph shown in fig. 2, 3 and 4 it is observed that
the BER for WDM system at all the channels decreases as the
transmitter power increases. It is also demonstrated that as
the booster gain increases the BER value decreases. Hence,
the system performance increases with increase in the
booster gain for all channels in a WDM system.
The effect of booster gain variation is greater at channel 8
compared to channel 1 and channel 16 i.e effect is greater
near to the central frequency of the WDM system and
decreases towards ends. Rate of decrement is more towards
the higher frequency end compared to the other lower
frequency end. Thus by increasing the transmitter power we
can improve the system performance.
Fig.2 BER vs. Transmitter Power in dBm at Channel 1 for
different Booster Gains
Fig.3 BER vs. Transmitter Power in dBm at Channel 8 for different
Booster Gains
Fig.4 BER vs. Transmitter Power in dBm at Channel 16 for
different Booster Gains
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2411
2) Q – Value Performance
Fig. 5, 6 and 7 shows the Q-value performance of a 16
channel WDM system at channel 1, 8 and 16. Here the
Q-value vs. transmitter power is plotted for various values of
booster gain.
Fig.5 Q-value vs. Transmitter Power in dBm at Channel 1 for
different Booster Gains
Fig.6 Q-value vs. Transmitter Power in dBm at Channel 8 for
different Booster Gains
Fig.7 Q-value vs. Transmitter Power in dBm at Channel 16 for
different Booster Gains
The booster gain effect increases as the transmitter power
decreases thus we need higher values of booster gain with
low transmitter powers to get the better performances.
B. Effect of number of Inline-Amplifiers
1) BER Performance
Fig.8 BER vs. Transmitter Power in dBm at Channel 1 for
different number of Inline Amplifiers
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2412
Fig.9 BER vs. Transmitter Power in dBm at Channel 8 for
different number of Inline Amplifiers
Fig.10 BER vs. Transmitter Power in dBm at Channel 16 for
different number of Inline Amplifiers
Fig. 8, 9 and 10 illustrates the graphs showing the BER
performance of a WDM system for various number of inline
amplifier. It is observed that as we install the inline amplifier
in the network the BER performance improves drastically.
From the graphs it is clear that the BER performance is best
among all these for N=4 for 100 km of fiber length where
inline amplifiers are installed after each fiber span of 25 km.
this fiber span length depends on the total distance for
communication and the value of the BER that must be
required for the successful transmission of a signal. The gain
of inline amplifier is fixed by analyzing the fiber cable
properties such as dispersion and polarization within in the
fiber cable used for the transmission purpuse
Fig. 11, 12 and 13 illustrates the graphs showing the
Q-value performance of the WDM system for various number
of inline amplifier. The graph demonstrates that the Q-value
of a WDM system increases as the transmitter power
increases.
From the BER performance graphs and Q-value
performance graphs it is clear that the Q-value varies
approximately inversely proportional to the BER value.
2) Q – Value Performance
Fig.11 Q-value vs. Transmitter Power in dBm at Channel 1 for
different number of Inline Amplifiers
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2413
Fig.12 Q-value vs. Transmitter Power in dBm at Channel 8 for
different number of inline Amplifiers
Fig.13 Q-value vs. Transmitter Power in dBm at Channel 16 for
different number of Inline Amplifiers
C. Effect of Fiber Length
1) BER Performance
Fig.14 BER vs. Transmitter Power in dBm at Channel 1 for
different Fiber Lengths
Fig.15 BER vs. Transmitter Power in dBm at Channel 8 for
different Fiber Lengths
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2414
Fig.16 BER vs. Transmitter Power in dBm at Channel 16 for
different Fiber Lengths
2) Q – Value Performance
Fig.17 Q-value vs. Transmitter Power in dBm at Channel 1 for
different Fiber Lengths
Fig.18 Q-value vs. Transmitter Power in dBm at Channel 8 for
different Fiber Lengths
Fig.19 Q-value vs. Transmitter Power in dBm at Channel 16 for
different Fiber Lengths
International Journal of Advanced Research in Computer Engineering & Technology (IJARCET)
Volume 3 Issue 7, July 2014
ISSN: 2278 – 1323 All Rights Reserved © 2014 IJARCET 2415
Fig. 14, 15 and 16 illustrates the BER performance graphs
at three different channels channel 1, 8 and 16 of a
16-channel WDM system. As the length of the fiber
decreases the losses associated with the fiber also decreases
and hence the BER value of the communication system
decreases and the Q-value increases as demonstrated by the
graphs shown in fig. 17, 18 and 19.
V. CONCLUSION
From the above discussion on simulation results of WDM
system performances for various parameters we conclude
that a WDM system provides its best performances at the
channel nearer to the central frequency of the WDM system.
It also concludes that the effect of parameters is also greater
nearer to the central transmission frequency.
The value of BER decreases with the use of the inline
amplifiers. And hence improves the Q-value performance.
Thus we concludes that the WDM system Q-value and BER
performance improves as the booster gain increases and fiber
length span decreases and hence help in increasing the
transmission distance for the same transmitter parameters.
VI. REFERENCES
[1] Arashid Ahmad Bhat, Anamika Basnotra and Nisha
Sharma, ―Design and Performance Optimization of
8-Channel WDM System‖, International Journal of
Advanced Research in Computer Science and Software
Engineering, Volume 3, Issue 4, April 2013.
[2] Gao Yan, Zhang Ruixia, Du Weifeng, and Cui
Xiaorong, ―Point-to-Point DWDM System Design and
Simulation‖, Proceedings of the 2009 International
Symposium on Information Processing (ISIP’09)
Huangshan, P. R. China, August 21-23, 2009, pp.
090-092.
[3] J. M. Kahn and K.-P. Ho, ―Spectral Efficiency Limits
and Modulation/Detection Techniques for DWDM
Systems‖, IEEE. J. on Sel. Topics in Quantum Electron.
10, 259-272, 2004.
[4] Jin Wang, Student Member, IEEE, and Joseph M. Kahn,
Fellow, IEEE, ―Impact of Chromatic and Polarization -
Mode Dispersions on DPSK Systems Using
Interferometric Demodulation and Direct Detection‖,
Journal of Lightwave Technology, Vol. 22, No. 2,
February 2004.
[5] Hadj Bourdoucen, Amer Alhabsi, ―Improvement of bit
error rate in optical fiber receivers‖, World Academy of
Science, Engineering and Technology, 52, 2009.
[6] Felix Abramovich, Polina Bayvel, ―Some statistical
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communication systems‖, IEEE Transactions on
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[7] S. M. Jahangir Alam, M. Rabiul Alam, Guoqing Hu and
Md. Zakirul Mehrab, ―Bit Error Rate Optimization in
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[8] S. P. Majumder, Member, IEEE, Afreen Azhari, and F.
M. Abbou, ―Impact of fiber chromatic dispersion on the
BER performance of an optical CDMA IM/DD
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[10] A. D’Errico, R. Proietti, L. Giorgi, G. Contestabile and
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[11] Yu YU, Xinliang ZHANG, Jose B. Rosas-Fernández,
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Phuket.
Vandana is a student pursuing M.Tech in
Electronics and communication
Engineering from Deenbandhu Chhotu Ram
University of Science and Technology
(DCRUST), Murthal, Sonepat, Haryana
(India). She received B.E. degree in
Electronics and Communication
Engineering from Maharshi Dayanand
University in year 2010.
Gitanjali Pandove has received her
M.Tech and B.Tech degree from AMU
Aligarh. Presently she is working as an
Assistant Professor at DCRUST, Murthal,
Sonipat, Haryana (India). In Electronics and
Communication Engineering, Department.
Her interest area includes Optical
communication, Image Processing and
Digital signal processing.