PERFORMANCE EVALUATION OF OPTICAL CODING TECHNIQUES FOR OPTICAL PON NETWORK

Abstract

In this dissertation, the two 2-D coding techniques has been designed for OCDMA system and their performance has been compared for passive optical network. The first coding technique i.e. Hadamard coding is designed for OCDMA system. In the first phase of this dissertation, twodimensional Optical Code Division Multiple Access System (2D-OCDMA) has been designed by using wavelength/phase Hadamard encoding technique. Usually Hadamard encoding technique is used in single domain i.e. wavelength domain. In this research work, 2D encoding technique is designed for OCDMA system in spectral as well as phase domain which will further improve the security. The proposed 2-D OCDMA increases the number of users by splitting the optical source to two orthogonal phase signals without the requirement to increase the code length as well as wavelengths. The proposed system requires a smaller number of LEDs as well as improves the security. The performance of the proposed system is analyzed by designing an OCDMA system for six users. The performance is analyzed in terms of Bit Error Rate (BER) and Quality Factor by increasing the number of users and for different distance range. In the second phase of this dissertation, Cyclic Shift (CS) coding technique is implemented for two dimensions i.e. wavelength and phase for Optical Code Division Multiple Access System (2D-OCDMA). Previously this cyclic shift encoding was done in spectral domain but in this dissertation the encoding technique has been proposed for spectral as well as phase domain. The proposed 2-D Cyclic shift code with spectral as well as phase domain increases the number of users by splitting the optical source to two orthogonal phase signals without the requirement to increase the code length as well as number of LEDs. Thus, the wavelength required for this proposed encoding structure is also reduced. In this paper, this encoding technique has been tested for four users. The performance is analyzed with increase in number of users. The proposed 2D is compared with the previously implemented 1D CS SAC-OCDMA code. Performances of the system designed show better result than the previously designed SACOCDMA Cyclic Shift code. The results of the proposed system in terms of parameters like bit error rate is within the range of 10-9. .