Increasing the Capacity of SAC-OCDMA by Using OFDM Modulation

Abstract

Optical CDMA (OCDMA) systems have received more attention because CDMA allows many users share the same transmission medium asynchronously and simultaneously with a high level of transmission security. In this paper, we describe the improved performance of the spectrum amplitude coding (SAC) OCDMA system using OFDM technique compare to SCM/SAC-OCDMA system. The theoretical results of proposed system shows that, the new SAC/OCDMA system with OFDM technique provides better performance compare to SCM/OCDMA system based on Random Diagonal Code (RD), the results evaluated based on BER, number of users and weight of code. Thus this system could be one promising solution to the symmetric high capacity access network with high spectral efficiency, reducing the required power and cost effective of broadband access network

Opto-Electronics Review

“…Step 2: The basic 4 × 8 ZCC-PTM (K = 4, w = 2, L = 8, λ c = 0) code matrix is given by the matrix 𝑃𝑇𝑀 4; 2 described in (2). Except for 𝑤 = 3, the ZCC-PTM code matrix is given by: As presented in (7), the first column of the code matrix [see (6)] is shifted to the middle of the 𝑃𝑇𝑀 4; 2 matrix as: ()…”

“…The capacity of OCDMA systems in terms of number of active users can be increased by using codes with large cardinality [4,5]. On the other hand, to enhance channel data rate and increase the number of users, combining of spectral amplitude coding OCDMA (SAC-OCDMA) system with other techniques such as subcarrier multiplexing (SCM) [6] and orthogonal frequency-division multiplexing (OFDM) [7] is required. Also, in the last few years, studies have shown that OCDMA network infrastructure is vulnerable towards several types of security attacks, such as eavesdropping where the safety component needs further safety requirements in the face of dramatic increases in network capacity [8,9].…”