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Optical CDMA system parameters limitations for AND subtraction detection scheme under enhanced double weight (EDW) code based on simulation experiment

Hmud I. S., Hasoon F. N., Shaari S.

Optica Applicata

2010

Vol. 40, nr 3

669--676

The work in this paper is a simulation experiment performed by a computer program to determine the OCDMA system parameters limitations. The system was built up with LED light source in the transmitter with filters to construct the code where the receiver is constructed based on AND-subtraction detection scheme. The system was designed to be compatible with the enhanced double weight (EDW) code, passive optical network (PON), P2P network connection and fiber to the home (FTTH) topology. Five system parameters were considered in this work: the number of users, the transmission distance, the bitrate, the chip spacing and the transmitted power. Optisys 6.0 software program was used as a simulator; the simulator considered the entire practical effects in the system, like nonlinearities, attenuation in the fiber and dispersion. This paper shows that for sufficient system performance parameters (BER ? 1×10–9, Q ? 6) the system can stand for the maximum number of 3 users, the maximum distance of 21 km and the minimum chip spacing of 0.2. The system also shows that it cannot work for any number of users or any distance without the amplifier.

AND-subtraction detection modified SNR equation for optical CDMA systems in PON applications

Hmud I. S., Hasoon F. N., Hatim F. A., Zahid A. Z. G., Shaari S.

Optica Applicata

2010

Vol. 40, nr 1

49--55

In this paper, AND-subtraction detection scheme compatible with OCDMA system and EDW code was simulated. The aim of the simulation is to adjust the AND-subtraction detection SNR equation for better accuracy in passive optical network (PON) applications. The simulation is performed by (optisys 06) software. The software considered the entire possible practical effects during implementation, such as dispersion, nonlinear effect of the fiber and attenuation of the fiber. The simulation results compared to the analytical results were based on SNR and BER mathematical equations. The comparison shows that the analytical equation should be modified so that the received power (Psr) be more accurate for PON applications.

Multi-rate transmissions on spectral amplitude coding optical code division multiple access system using random diagonal codes

Fadhil H. A., Aljunid S. A., Ahmad R. B.

Optica Applicata

2009

Vol. 39, nr 2

225-232

In this paper, we study the use of a new code called random diagonal (RD) code for spectral amplitude coding (SAC) optical code division multiple access (OCDMA) networks, using fiber Bragg-grating (FBG). FBG consists of a fiber segment whose index of reflection varies periodically along its length. RD code is constructed using a code level and data level, one of the important properties of this code is that the cross correlation at the data level is always zero, which means that phase intensity induced phase (PIIN) is reduced. We find the performance of the RD code to be better than those of the modified frequency hopping (MFH) and Hadamard codes. It has been observed from simulation and theoretical results that considering the bit error rate (BER), the RD code performs significantly better than other codes. The ability of RD codes to support simultaneous transmissions at different bit rates is shown through simulated results of the BER and the eye patterns. 10 Gbps and 2.5 Gbps data transmissions have been successfully demonstrated together with FBG decoding scheme for canceling the code level from SAC-signal.