BER and Q-Value Performance Analysis of WDM Network …ijarcet.org/wp-content/uploads/IJARCET-VOL-3-ISSUE-7-2409-2415.pdf · technique to communicate the channels with very low channel

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




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






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






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


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.








different number of inline Amplifiers



C. Effect of Fiber Length

1) BER Performance


different Fiber Lengths


















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

remarks on the derivation of BER in amplified optical

communication systems‖, IEEE Transactions on

Communications, Vol.4, No. 9, September, 1997.

[7] S. M. Jahangir Alam, M. Rabiul Alam, Guoqing Hu and

Md. Zakirul Mehrab, ―Bit Error Rate Optimization in

Fiber Optic Communications‖, International Journal of

Machine Learning and Computing, Vol. 1, No. 5,

December 2011.

[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

transmission system‖, IEEE Photonics Technology

Letters, Vol. 17,No. 6, June 2005.

[9] Md. Mobarok Hossain Rubel, Syed Golam Mahmud, ―

BER Performance Analysis for Optical Communication

using DPSK Modulation‖, International Journal of

Computer Applications (0975 – 8887) Volume 59 No.9,

December 2012.

[10] A. D’Errico, R. Proietti, L. Giorgi, G. Contestabile and

E. Ciaramella, ―WDM-DPSK detection by means of

frequency-periodic Gaussian filtering‖, Electronics

Letters, Vol. 42 No. 2, 19th January 2006.

[11] Yu YU, Xinliang ZHANG, Jose B. Rosas-Fernández,

Dexiu Huang, Richard V. Penty, Ian H. White,

―Proposal for a novel and simple WDM NRZ-DPSK

system‖, Front. Optoelectron. China, 2(3): 253–258,

2009.

[12] Iftikhar.Rasheed, Muhammad Farrukh Amin. Sial,

Khawaja Salman. Ali, and Tariq.Mehboob, ―Evaluation

of Optical Receiver Sensitivity-Bit Error Rate (BER)/Q

factor‖, International Conference on Computer and

Communication Technologies, May 26-27, 2012

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.

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BER and Q-Value Performance Analysis of WDM Network …ijarcet.org/wp-content/uploads/IJARCET-VOL-3-ISSUE-7-2409-2415.pdf · technique to communicate the channels with very low channel