Comparative analysis of optical 2D codes using (n, w, λa, λc) optical orthogonal codes for optical CDMA

Abstract

Hybrid two dimensional (2D) wavelength-hopping time-spreading coding techniques have been focused now days for Optical Code Division Multiple Access (OCDMA) systems to increase the capacity of system. In this paper, design and comparative analysis of five different 2D coding techniques has been performed. These codes use Synchronized Quadratic Congruence sequences (SQC), Prime Code sequences (PC), Synchronized Prime Sequences (SPS) and One-Coincidence Frequency Hopping Code (OCFHC) for wavelength hopping and (n, w, λ_a, λ_c) one dimensional optical orthogonal codes for time spreading respectively along with Extended Reed Solomon (E-RS) codes. It has been observed that SQC/OOC code inspite of having larger value of cross correlation than other codes under consideration, out performs due to its ability to support a larger code weight. The comparison on the basis of BER shows that irrespective of the increase in number of hits due to higher code weight, SQC/OOC provides better code performance and hence supports large number of users in the system. The results are reported on the basis of maximum auto- and cross correlation function, cardinality and bit error rate (BER).