International Research Journal of Engineering and Technology (IRJET) e-ISSN: 2395-0056 Volume: 05 Issue: 07 | July 2018 www.irjet.net p-ISSN: 2395-0072 © 2018, IRJET | Impact Factor value: 7.211 | ISO 9001:2008 Certified Journal | Page 2354 Analytical Solution of Dispersion Compensation Using Walsh Code over Pseudo Random Binary Sequence in Optisystem Safalata Singh Sindal 1 , Anurag Paliwal 2 1 M. Tech. Student, Department of Electronics and Communication Engineering, Geetanjali Institute of Technical Studies, Udaipur, Rajasthan, India 2 Assistant Professor, Department of Electronics and Communication Engineering, Geetanjali Institute of Technical Studies, Udaipur, Rajasthan, India ---------------------------------------------------------------------***--------------------------------------------------------------------- Abstract - Since dispersion severely damages the data transmission in optical fiber, we proposed a dispersion compensation model in order to achieve the high-speed optical communication system. Pseudo-random binary sequence (PRBS) is most commonly adopted as the input sequence to the optical network in previous proposed models. In this paper, we focused mainly on designing a dispersion compensation model that uses Gold sequence and Walsh code as its input sequence instead of PRBS. The values of Q-factor, bit error rate (BER), eye height and threshold are determined for each model and are compared with respect to 40 km fiber length using OPTISYSTEM simulation. The simulation results of the model having Walsh code are found to be better over PRBS with comparatively high Q- factor and low min. BER. Key Words: Walsh code, PRBS, dispersion compensation, Q-factor, min. BER, Optisystem. 1. INTRODUCTION The continuously increasing demands of bandwidth of communication system are giving rise to the need of installing new communication links, which would require huge investments. So it is preferred to increase the capacity of the existing fiber links of communication system carriers by using different methods in optical communication system [1]. The capacity of the system can be increased by minimizing the losses. Dispersion is considered to be one of the major parameter in optical fiber losses. Dispersion is a critical factor that limits the quality of signal transmission over optical links and leads to the broadening of light pulses. In previous research papers related to dispersion compensation technique, one of the most efficient technologies used to overcome chromatic dispersion problem is Fiber Bragg Grating (FBG) due to its low cost and its negligible effect. To encounter the attenuation effects various types of amplifiers such as Erbium doped fiber amplifier (EDFA), Semiconductor optical amplifier (SOA) and Raman amplifier have been introduced. However, EDFA still provide better results. In this paper, we propose a new model which includes the implementation of FBG and EDFA to overcome chromatic dispersion and to optimize the quality of the received signal. The main area of our work is the type of input source used in the dispersion compensation network. In the first section, we present a study of the model previously proposed by other authors i.e. dispersion compensation network with PRBS as input sequence. Then using the optimized setting parameters we compare the transmission system under study with the proposed model having Walsh code as its input. The comparison has been done in terms of Q-Factor, BER, eye height, threshold value and their eye diagrams at the received signal. The simulation results demonstrate the high efficiency of the developed transmission system. 2. PSEUDO RANDOM BINARY SEQUENCE A Pseudo random binary sequence, also commonly known as pseudo- noise (PN) sequence is used widely in digital communication. The bit pattern of a sequence never repeats if it is a truly random sequence. The meaning of the qualifier "pseudo" is that the sequence is not truly random. Basically, it is periodic with a specific period, and shows some characteristics of a random white sequence within that period. Thus PRBS is a semi-random sequence because it appears to be random within the length of sequence and hence fulfills the needs of randomness, but the whole sequence repeats indefinitely [2]. Pseudo random sequence plays a significant part in encoding of message for efficient message transmission. It is most commonly adopted input sequence to the optical network in previous models proposed by other authors. PRBS is considered as an ideal test signal, since it simulates the random characteristics of a digital signal. It is a bit stream of occurring randomly Ǯͳǯs and ǮͲǯs, with some unique properties. These sequences are statistically random sequences with low correlation property. These sequences can be generated very easily and quickly through some simple electronic circuits. PRBS is generated by Linear Feedback Shift Registers (LFSR). If the number of stages in LFSR is r then P=2 r -1 (1) Equation (1) uses the parameter P that is the period of the sequence. PRBS serves as a reference pattern with known random characteristics for the analysis, optimization and