Thanaa Hussein Abd

A new technique for reduction of Multi-Access Interference in SAC-OCDMA system using different optical filters

A construction of new code family for Spectral Amplitude Coding Optical Code Division Multiple Accesses (SAC-OCDMA) has been proposed. This new code family we call it Dynamic Cyclic Shift (DCS) code. The DCS code reduced the effect of Multi Access Interference (MAI) due to it is the property of variable cross correlation. We find that the performance of the DCS code is a batter than Random Diagonal (RD) code and Modified Frequency Hopping (MFH) code. Through the mathematical calculation and simulation analysis, for the bit-error rate of DCS code is significantly better than other SAC-OCDMA codes such as RD and MFH codes. We analyze the performance of the proposed codes and examine how the code size and correlation properties are related. Two different decoding schemes are used for implementing the SAC-OCDMA system: Fiber Brag Grating (FBG) and optical Butterworth filter such as Arrayed Wave Guide Grating (AWG) optical filter. Simulation results show that performance of AWG filter is better than Fiber Brag Grating for optical system with 10 Gbps bit rates. Finally, in terms of system cost, FBG offers cost effective than other type of filters (e.g., AWG, thin film filter)

Design and evaluation Fiber-to-the-Home network based on DCS code

In this paper, we propose a new design of Fiber-to-the-Home (FTTH) network based on Spectral Amplitude Coding Optical Code Division Multiple Access (SAC-OCDMA). The FTTH network based on SAC-OCDMA system is tested by employing the Dynamic Cyclic Shift (DCS) code. Whereas, the DCS code is selected due to reduced and mitigates the effect of Multi Access Interference (MAI) in comparing with existing SAC-OCDMA codes. The AND subtraction technique is employed at the at the receiver part of the FTTH network structure due to its compatibility with DCS code to suppress the effect of the MAI. The results, which are obtained mainly from experimental simulations, are presented. In the simulation analysis, the study focused on: the effect of distance, data rate, and noise power on system performance. Finally, Simulation results show that DCS code is expected to become more important in the future of the FTTH network environment.

Performance Evaluation of Hybrid SCM/SAC-OCDMA Transmissions System using Dynamic Cyclic Shift Code

Abstract In this paper, the performance of a hybrid scheme of Subcarrier Multiplexing (SCM) technique in a Spectral Amplitude Coding (SAC) Optical Code Division Multiple Access (CDMA) transmissions system is evaluated. The hybrid system is design using new code family; we call it Dynamic Cyclic Shift (DCS) code. The DCS code design for SAC-OCDMA system to reduce the effect of Multi Access Interference due to it property of low cross-correlation (λC ≤ 1) between code words. In contrast, the SCM scheme shows the ability to increase the data rate of SAC-OCDMA system. Consequently, the hybrid SCM/SAC-OCDMA system could be one promising solution to the high-capacity access network with low cost effective, good flexibility and enhanced security, which makes an attractive candidate for next-generation broadband access network.

Suppression of the Phase Induced Intensity Noise based on the Dynamic Cyclic Shift code for SAC-OCDMA access networks

A new code family for Spectral Amplitude Coding Optical Code Division Multiple Assess (SAC-OCDMA) system has been proposed in this paper. The new code family we call it Dynamic Cyclic Shift (DCS) code. The DCS code has many advantages. However, the DCS code can be generated without code parameter limitation. In addition, the shorter code length and variable cross correlation (λc ≤ 1) of the DCS code can improve the SAC-OCDMA system performance. The mathematical results and simulation analysis shows that the DCS code in terms of the Bit-Error-Rate (BER) and eye diagram can effect on the suppression of Phase Induced Intensity Noise (PIIN). The simulation analysis carried the data rate 10 Gbps for 20 km with low BER value comparing with former SAC-OCMA code systems.

A New Technique for Reduction the Phase Induced Intensity Noise in SAC-OCDMA Systems

Abstract A new code for reduction the phase induced intensity noise has been presented. The new code is proposed for Spectral Amplitude-Coding Optical Code Division Multiple Accesses (SAC-OCDMA). This new code family we call it Dynamic Cyclic Shift (DCS) code. The DCS code reduced the effect of Multi Access Interference (MAI) due to it is the property of variable cross correlation. We find that the performance of the DCS code is a batter than other SAC-OCDMA codes such as; Random Diagonal (RD) code, Modified Quadratic Congruence (MQC) code and Modified Frequency Hopping (MFH) code. Through the mathematical calculation and simulation analysis, for the bit-error rate of DCS code is significantly better than other SAC-OCDMA codes, the effect of Phase Induced Intensity Noise is reduced. In addition, proofof-principle simulations of 10 Gb/s for 20 km have been successfully demonstrated and achieved low BER compared to the other codes.

A New Algorithm for Development of Dynamic Cyclic Shift Code for Spectral Amplitude Coding Optical Code Division Multiple Access Systems

Abstract This article presents a new code—the dynamic cyclic shift code—for spectral amplitude coding–optical code division multiple access systems. One of the important properties of the dynamic cyclic shift code is that the number of users can be increased without increasing the weight value. System performance was evaluated by using both theoretical analysis as well as the simulation experiment. The analysis results show that the proposed dynamic cyclic shift code can support more users in spectral amplitude coding–optical code division multiple access systems compared to spectral amplitude coding–optical code division multiple access codes. It was ascertained by performance evaluation that the dynamic cyclic shift code possesses ideal properties for use in spectral amplitude coding–optical code division multiple access systems.

New code for spectral-amplitude coding optical code-division multiple-access systems

In this paper we present a novel code family for SAC-OCDMA system. The new code technique is called Dynamic Cyclic Shift (DCS) code. Which more flexible in selection the code length with variable cross correlation. Furthermore, incase of increasing the number of users there is no need to increase the weight value. In addition the code construction is very simple and easy in compare with the former codes. The results show that the proposed code is effective to reduce the MAI, PIIN, while maintaining a good signal to noise ratio and bit error probability. The results obtained for the DCS code were compared with those obtained from different coding schemes Modified Quadratic Congruence (MQC) code and Random Diagonal (RD) code.

A study on rain attenuation impact on hybrid SCM-SAC OCDMA-FSO system

This paper proposes a new approach that utilizes Free Space Optics (FSO) in hybrid SCM-SAC-OCDMA system. Among the numerous properties of this approach, the most important is a reduction of the multi access interference (MAI) and the overcoming of the overlapped wavelengths. Simplicity, cost-effectiveness, and free license with (MD) code have made this approach a compelling candidate for Last Mile Communications. This paper proposes the hybrid system for Free Space Optic (FSO) and also shows the effect of rain attenuation on this proposed system. The study is made according to the Malaysian weather conditions (Kuala Lumpur) through simulation. The simulation results proved that the MD code hybrid system produces less Bit-Error Rate (BER) at storm rain up to 500 m range. In addition to that the data rate is set to 1 Gb/s and power 6 dBm.

Impact of attenuations on the hybrid Subcarrier Multiplexing SAC OCDMA-FSO system

The wireless systems in Malaysia are influenced by turbulent weather which leads to a large signal fading or attenuation. This paper proposes using the hybrid Subcarrier Multiplying (SCM)-Spectral Amplitude Coding (SAC) Optical Code Division Multiple Access (OCDMA) system based on Multi-Diagonal (MD) code using Free Space Optic (FSO). The study has found out that the hybrid system can be used in the mesh network. The proposed hybrid technique has been analyzed by taking into account the effects of the haze and rain attenuations. Furthermore, we have described modulation scheme, atmospheric effects, data security, the FSO mesh network and simulation. The above method produces less Bit-Error Rate (BER) at storm rain and at heavy haze.

New Technique for Suppression Four-Wave Mixing Effects in SAC-OCDMA Networks

A new technique invented for suppressing the FWM in SAC-OCDMA systems based on adding idle code at the sideband of the code construction to generate the virtual FWM power at the sideband of the signal, and then by subtracting these virtual FWM power from the original FWM power in the system and filtering the data part at the channel. This technique is applied for both SAC codes, Random Diagonal Code (RD) and Multi Diagonal Code (MD). Moreover, in terms of cost, the reported technique is considered a cost-effective as the LED light source is used to generate the sideband codes. The results showed that the FWM reduced approximately 25 dBm after using the technique. For example, in the RD code the FWM power at 40km fiber length and input power is 15 dBm using the SMF fiber type is approximately -55 dBm before using the technique, after using the technique at the same values of parameters the FWM power is approximately -90dBm. In other words, at the MD code the FWM power before using the technique is approximately -61 dBm, the same parameters values, however after using our technique the value of the FWM power is approximately -81dBm. However, These results gave impact on the Bit Error Rate (BER) also, for example the value of BER in the RD code at the input power -10dBm and 35km fiber length before using the technique is 1.6×10-23 and after using the technique the value of BER will become 4.05×10-28. In addition at the MD code the BER value before using the technique is 9.4×10-22 and after using the technique the value of BER is 7.4×10-31.