10Gbps Optical Line Using Electronic Equalizer and its Cost Effectiveness Dr. Pulidindi Venugopal #1 , Y.S.V.S.R.Karthik *2 , Jariwala Rudra A #3 #1 VIT Business School, VIT University Vellore, Tamilnadu, India 1 pulidindi.venu@vit.ac.in *2 B.Tech, (Final Year), SCSE, VIT University karthikarama7@gmail.com #3 B.Tech, (Final Year), SCSE, VIT University Abstract— Chromatic Dispersion (CD) is a very important factor in the transmission of data over a long distance. To overcome the loss caused by CD, we can use many techniques. In this paper we propose to do the same by using Electronic Equalization technique. It also helps to eliminate ISI at the receiver end by proper thresholding, the transmitted bit sequence can be obtained without any errors. The paper also analyzes the cost effectiveness of using the electronic equalizer in place of optical equalizers. Keywords— Chromatic Dispersion, Electronic Equalizer, NRZ pulse, ISI I. INTRODUCTION Chromatic Dispersion: Fiber limitations like chromatic dispersion (CD) severely affect the performance of the high speed optical fiber transmission systems. Dispersion is one of the important parameters and should be carefully monitored during the design process. To avoid the extra power required due to the nonlinear effects, fibers with a small but non zero CD is required in long-haul transmission system. CD is an important issue in single mode fibers and causes Inter Symbol Interference (ISI) in the pulse. This occurs because the components of light traverse with different velocities due to the differences in frequency. It is also called Group Velocity Dispersion. The process of balancing the positive and negative dispersion over the length of the fiber is called dispersion management. The total dispersion is near zero or within an acceptable limit, when the optical pulses reach the receiver. It is inversely proportional to the square of the data rate of the signal. Single mode fibers have CD approximately 17 ps/nm.km and have minimum attenuation when they operate around 1550 nm. Hence, the accumulation of the dispersion components limits the distance of transmission to approximately 55 km on a 10Gbits/s system if dispersion compensation techniques are not used. One of the methods to expand the fiber’s capacity is to enhance the number of DWDM channels transferred over a single fiber. The greater channel density has to compensate for the dispersion as well as the dispersion slope.[2] Electronic Dispersion Compensation (EDC) has become one of the most important parts of an optical transponder design. At present, most of the installed optical fiber in the current metropolitan environment consists of single mode fiber with a CD value of about 17ps/nm/km at a wavelength of 1550 nm. In the current cost driven metro market, Electronic Dispersion Compensation can become a very valuable tool in enhancing the existing fiber links to higher bit rates. New applications using feed forward equalizer and decision feedback equalizer are being developed by International Telecommunication Union (ITU-T) to provide seamless up gradation facilities to the existing optical network systems.[2]. Cost Effectiveness: Comparing the conventional costs of an ADFE and an electronic equalizer, we can see that the cost of operation decreases by 75-80% when an electronic equalizer is used as opposed to an ADFE. II. EQUALIZATION HYPOTHESIS 1. By replacing the adaptive decision feedback equalizers with electronic equalizers will enhance performance: Chromatic dispersion compensation methods: For eliminating or mitigating the chromatic dispersion, various techniques have been presented. They can be classified into two main groups :( i) Optical compensation technique (ii) Electronic compensation. Optical Compensation: There are several methods for optical dispersion compensation. i. Conventional dispersion compensation fiber This method used dispersion compensated fibers (DCF). Conventional dispersion compensation fibers (cDCF) have a very high negative dispersion in the C and L bands and can be effectively used in dispersion compensation in those bands. Further reduction in the core area of the new type of dispersion compensation fibers, a little slope correction has been made possible in conventional single mode fibers. Dr. Pulidindi Venugopal et.al / International Journal of Engineering and Technology (IJET) ISSN : 0975-4024 Vol 5 No 4 Aug-Sep 2013 3307