Signal quality of dispersion managed quasi linear high bit rate

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Signal quality of dispersion managed quasi linear high bit rate

  1. 1. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME108SIGNAL QUALITY OF DISPERSION MANAGED QUASI-LINEARHIGH BIT RATE OPTICAL TRANSMISSION SYSTEMMir Zayed Shames1, Md. Surat-E-Mostafa2, Imtiaz Ahmed31(Electrical and Electronic Engineering, Ahsanullah University of Science and Technology,141-142 Love Road, Tejgaon Industrial Area Dhaka-1208, Bangladesh,)2(Electrical and Electronic Engineering, Ahsanullah University of Science and Technology,141-142 Love Road, Tejgaon Industrial Area Dhaka-1208, Bangladesh,)3(Electrical and Electronic Engineering, Ahsanullah University of Science and Technology,141-142 Love Road, Tejgaon Industrial Area Dhaka-1208, Bangladesh,)ABSTRACTThis paper investigates the performance of a quasi-linear optical fiber periodictransmission system by numerical simulation based on Split Step Fourier (SSF)transformation method. Comparisons of Quality Factor over the Transmission Length,Transmission Power, Bit Rate and Residual Dispersion between two models (DCF-SMF andSMF-DCF) are obtained. The simulation results demonstrate that by rearranging thedispersion management system significant performance improvement can be achieved.Keywords: Bit Rate, DCF-SMF, High Bit Rate, Quality Factor, Quasi-Linear, ResidualDispersion, SMF-DCF, Transmission length, Transmission power1. INTRODUCTIONOptical fiber communication systems are evolving from 40 Gb/s to 160 Gb/s perchannel. At 40 Gb/s, since the signals have wider bandwidth and higher signal power, thedispersion compensation must be carefully optimized to control the interaction between thedispersion and nonlinearity. In our work, we have considered the optical transmission of 1000km to observe the changes in Q for different parameters. We focus here on the effect on Qwith the changes in different parameters of the fiber. These observations can be applied toimprove the signal quality when transmitting through next generation ultra-high capacityINTERNATIONAL JOURNAL OF ELECTRONICS ANDCOMMUNICATION ENGINEERING & TECHNOLOGY (IJECET)ISSN 0976 – 6464(Print)ISSN 0976 – 6472(Online)Volume 4, Issue 3, May – June, 2013, pp. 108-114© IAEME: www.iaeme.com/ijecet.aspJournal Impact Factor (2013): 5.8896 (Calculated by GISI)www.jifactor.comIJECET© I A E M E
  2. 2. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME109communication network that corresponds to the bit rate ranges from 40 Gb/s to 160 Gb/s.These investigations will in turn help to improve the dispersion compensation and otherfactors of the fiber that results in signal weakness. As a result, high signaling rate and robustsignal could be desired through the fiber and at the output.This research work is intended to address the effects on the signal quality factor Qwith the change in fiber length, bit rate, power and residual dispersion in a high capacitydispersion managed (DM) quasi-linear system. Before that, we would like to mention someprevious works which have been reported in the literature regarding the quasi-linear systemand high bit rate system. Analytical description of the propagation of quasi-linear opticalpulses in SDM systems is presented by M. J. Ablowitz [1]. Similar study has been done by A.Biswas [2]. A. Mecozzi [3] has analyzed the intrachannel nonlinear effects in highlydispersed optical pulse transmission. For high capacity systems, J. Berthold [4] has studiedthe evolution of optical networking. Higher bit rates for quasi-linear optical datatransmission systems via constrained coding have studied by V. Pechenkin [5]. M. Oukil [6]has studied the optimization of high bit rate optical fiber transmission. For Q factor, S. Ohteru[7] has studied optical signal quality monitoring scheme that is independent of the signalformat.2. THEORY2.1 General NLS EquationThe Nonlinear Schrödinger (NLS) equation with damping and periodic amplification,in the dimensionless form is:iq୸ ൅ୈሺ୸ሻଶq୲ ୲ ൅ |q|ଶq ൌ െiΓq ൅ iሾeΓ୸౗ െ 1ሿ ∑ δሺz െ nzୟሻq୒୬ୀଵ (1)Here, Γ is the normalized loss coefficient, za is the normalized characteristic amplifierspacing, and z and t represent the normalized propagation distance and the normalized time,respectively, expressed in the usual non dimensional units.Also, D (z) is used to model strong dispersion management. The fiber dispersion D (z)is decomposed into two components namely a path-averaged constant value δa and a termrepresenting the large rapid variation due to large local values of the dispersion [2].2.2 DMNLS EquationIn this section, dispersion managed nonlinear Schrödinger (DMNLS) equation isconsidered. We begin the analysis with the perturbed NLS equation in the presence ofdispersion variation, loss, and lumped amplification [2]. Optical pulse propagating in a fiberwith periodic dispersion management and amplification can be expressed by dimensionlessnonlinear Schrödinger (NLS) equation as:iδ୙δ୞െୠሺ୸ሻଶδమ୙δ୘మ ൅ sሺZሻ|U|ଶU ൌ iGሺZሻU (2)Where, U (Z, T), T and Z are the normalized complex envelope of electric field,retarded time, and transmission distance, respectively. B (Z) represents fiber dispersion, s (Z)
  3. 3. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME110represents the effective fiber nonlinearity and G (Z) represents gain by optical amplifier for G> 0 or fiber loss for G < 0 in normalized units, respectively [8].3. MODELS• Dispersion Compensating Fiber – Single Model Fiber (DCF-SMF)• Single Mode Fiber - Dispersion Compensating Fiber (SMF-DCF)3.1 Dispersion Compensating Fiber - Single Mode Fiber (DCF-SMF)Figure 1 shows the pictorial representation of Dispersion Compensating Fiber - SingleMode Fiber (DCF-SMF). It is evident from the pictorial representation that DCF-SMF isformed by combining together a dispersion compensating fiber and a single mode fiber. Nrepresents the number of configurations of this model in the transmission network. Each spanof this model consists of DCF, SMF and an amplifier. In our case, the value of N is 40 whichmean that the span is repeated 40 times throughout the transmission network.Figure 1: Pictorial representation of DCF-SMF Model3.2 Single Mode Fiber - Dispersion Compensating Fiber (SMF-DCF)Figure 2 shows the pictorial representation of Single Mode Fiber – DispersionCompensating Fiber (SMF-DCF). It is evident from the pictorial representation that SMF-DCF is formed by combining together a single mode fiber and a dispersion compensatingfiber with an amplifier. Each span of this model consists of SMF, DCF and amplifier. Thisspan is periodically repeated for N times. Here also, the value of N is 40 which mean that thespan is repeated 40 times throughout the transmission network.
  4. 4. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME111Figure 2: Pictorial representation of SMF-DCF Model4. RESULTS AND DISCUSSIONSimulation results are presented by using the g++ compiler and GNU plot. Followingthe analytical approach presented in section 2, Comparison of Quality Factor against theLength and Transmission Power between DCF-SMF and SMF-DCF are evaluated. Thestandard value of Quality Factor, Q is 6. So, it is desired to keep the value of Q over 6.Plot of Quality Factor vs. Transmission Length (For DCF-SMF and SMF-DCFmodels) is shown in fig. 3. From the fig, it is evident that for DCF-SMF model the signal cantravel up to 1300 km keeping the quality factor above the standard line, whereas for SMF-DCF model the signal can travel up to 1425 km which is 125 more than DCF-SMF model.Figure 3: Comparison of Quality Factor over Transmission Length between DCF-SMF andSMF-DCF models
  5. 5. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME112Figure 4: Comparison of Quality Factor over Transmission Power between DCF-SMF andSMF-DCF modelsPlot of Quality Factor vs. Transmission Power (For DCF-SMF and SMF-DCFmodels) is shown in fig. 4. From the fig, it is evident that SMF-DCF model transmit signalswith low power more efficiently than DCF-SMF model which is a requirement of good quasi-linear system.Plot of Quality Factor vs. Bit Rate (For DCF-SMF and SMF-DCF models) is shownin fig. 5. From the fig, it is evident that DCF-SMF model can transmit data up to 60 Gb/sefficiently where as SMF-DCF model can transmit data at a higher bit rate which is up to 80Gb/s. So we can transmit data much faster.Figure 5: Comparison of Quality Factor over Bit Rate between DCF-SMF and SMF-DCFmodels
  6. 6. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME113Figure 6: Comparison of Quality Factor over Residual Dispersion between DCF-SMF andSMF-DCF modelsPlot of Quality Factor vs. Residual Dispersion (For DCF-SMF and SMF-DCFmodels) is shown in fig. 6. From the fig, it is evident that, at 0 RD the signal quality of DCF-SMF model stays just above 6 whereas for SMF-DCF model the signal quality remains near 8which is more efficient than DCF-SMF model.The Assumption parameters for both models for different simulations are as shown inTable 1.Table 1: Assumption ParametersParametersValue whilesimulatingTransmissionLengthValuewhilesimulatingPowerValue whilesimulating BitRateValue whilesimulatingResidualDispersionUnitSpan Length (L) 50 50 50 50 kmLength of SMF (L1) 42.5 42.5 42.5 42.5 kmLength of DCF (L2) 7.5 7.5 7.5 - kmDispersion of L1 17 17 17 17 ps/nm/kmDispersion of L2 -96.33 -96.33 -96.33 -96.33 ps/nm/kmBit Rate 40 40 20 to 160 40 Gb/sDuty Cycle (N) 40 40 40 40 -Wavelength ( ) 1.55 1.55 1.55 1.55 µmPeak power (Po) 2 1 to 10 2 2 mWResidual dispersion(RD)0 0 0 +15 to -15 -
  7. 7. International Journal of Electronics and Communication Engineering & Technology (IJECET),ISSN 0976 – 6464(Print), ISSN 0976 – 6472(Online) Volume 4, Issue 3, May – June (2013), © IAEME1145. CONCLUSIONWe have observed the change in Quality Factor with the change in Transmissionlength, Transmission Power, Bit Rate and Residual Dispersion. These observations areimportant in making the optical fiber transmission system more efficient and effective.Moreover, the comparison will help to determine the superiority among the two modelsdiscussed. Overall SMF-DCF model can transmit low power signal at a much higher bit rate,to a longer distance maintaining a higher quality of the signal than DCF-SMF model.6. ACRONYMSDCF-SMF - Dispersion Compensating Fiber – Single Model FiberDM - Dispersion ManagedDMNLS - Dispersion Managed Nonlinear SchrödingerNLS - Nonlinear SchrödingerSMF-DCF - Single Mode Fiber - Dispersion Compensating FiberSSF - Split Step FourierREFERENCES[1] Mark J. Ablowitz, Toshihiko Hirooka, Managing nonlinearity in strongly dispersionmanaged optical pulse transmission, Journal of the Optical Society of America B, vol.19, no. 3, Mar. 2002[2] Biswas, A., Theory of quasi-linear pulses in optical fibers, Optical Fiber Technol., vol.10, pp. 232-259, 2004[3] A. Mecozzi, C. B. Clausen and M. Shtaif, Analysis of intrachannel nonlinear effects inhighly dispersed optical pulse transmission, IEEE Photonics Tech. Letters, vol. 12, pp.392-394, 2000[4] Joseph Berthold, Adel A. M. Saleh, Loudon Blair, Jane M. Simmons, OpticalNetworking: Past, Present, and Future, J. Lightwave Technol., vol. 26, no. 9, May 2008[5] Pechenkin, V., Kschischang, F. R., High Bit Rates for Quasi-Linear Optical DataTransmission Systems via Constrained Coading, Optical Fiber communiationConference, March 2006[6] Oukli, M., Kandouci, M., Bouzid, M., and Bendaoud, A., Study and Optimization ofHigh-Bit Rate Optical Fiber Transmission, Serbian Journal of Electrical Engineering,vol. 5, no. 2, pp. 361-370, Nov. 2008[7] Ohteru, S., Takachio, N., Optical Signal Quality Monitor Using Direct Q-FactorMeasurement, IEEE Photonics Techonol. Letters, vol. 11, no. 10, Oct. 1999[8] Marc Hanna, David Boivin, and Pierre-Ambroise Lacourt, Calculation of optical phasejitter in dispersion-managed systems by use of the moment method, Journal of theOptical Society of America B, vol. 21, no. 1, January 2004[9] S.K Mohapatra, R. Bhojray And S.K Mandal, “Analog And Digital Modulation FormatsOf Optical Fiber Communication Within And Beyond 100 Gb/S: A ComparativeOverview” International Journal of Electronics And Communication Engineering&Technology (IJECET), Volume 4, Issue 2, 2013,pp. 198 - 216, ISSN Print: 0976-6464, ISSN Online: 0976 –6472

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