scholarly journals Enhanced Spectral Amplitude Coding OCDMA System Utilizing a Single Photodiode Detection

2018 ◽  
Vol 8 (10) ◽  
pp. 1861 ◽  
Author(s):  
Somia Abd El-Mottaleb ◽  
Heba Fayed ◽  
Ahmed Abd El-Aziz ◽  
Mohamed Metawee ◽  
Moustafa Aly
Keyword(s):  
System Performance ◽  
Multiple Access ◽  
Group Velocity Dispersion ◽  
Single Mode ◽  
Fiber Amplifier ◽  
Single Mode Fiber ◽  
Spectral Amplitude ◽  
Erbium Doped Fiber Amplifier ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

In this paper, the performance of a spectral amplitude coding-optical code division multiple access (SAC-OCDMA) system is investigated utilizing a single photodiode (SPD) detection technique. The proposed system uses enhanced double weight (EDW) codes as signature codes with three simultaneous users to overcome both phase-induced intensity noise (PIIN) and multiple access interference (MAI). In addition, a dispersion compensating fiber (DCF) is used in order to decrease the group velocity dispersion (GVD) caused in the single mode fiber. An erbium-doped fiber amplifier (EDFA) is used to overcome the attenuation. The use of both DCF and EDFA leads to an appreciable enhancement in the system performance. The system performance is evaluated through its bit error rate (BER), Q-factor, and received power. A comparison between the EDW codes and modified double weight (MDW) codes on the SAC-OCDMA system is demonstrated. Simulation is carried out through Optisystem ver. 7. The simulation results show that: (a) using an avalanche photodiode (APD) over PIN photodiode allows data transmission over longer distances; (b) the use of DCF improves the system BER;(c) using MDW codes gives better BER than using EDW codes.

scholarly journals An Efficient Method to Reduce an MAI’s Effect in Spectral Amplitude Coding OCDMA Network

2017 ◽  
Vol 2 (6) ◽  
pp. 1
Author(s):  
Kamal Elsiddig Amaseb ◽  
Hassan Yousif Ahmed ◽  
Medien Zeghid
Keyword(s):  
Optical Communication ◽  
System Performance ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Integer Number ◽  
Quadratic Congruence ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Multiple access interference (MAI) in spectral-amplitude coding, optical code division multiple access (SAC-OCDMA) scheme hardly limits the system performance. This problem increases proportionally with the amount of concurrent users. In addition, phase induces intensity noise (PIIN) coming from the spontaneous emission process of light source is extra impairment leads to system drop needs to be tackled too. Towards overcome the specified problems, vector combinatorial (VC) codes which based on grouping of certain vectors is proposed. Any positive integer number can be used in both weighs and user parameters in code building procedure, these technique nominees our code to be a potential reliable applicant for future optical communication schemes. Such flexibility is an exceptional property for VC compared to SAC-OCDMA counterparts’ codes. Compared with the systems employing Hadamard, Modified Frequency Hopping (MFH), Modified Quadratic-Congruence (MQC), and Modified Double Weight (MDW), numerical results show that, the VC is effective to reduce the power of MAI and PIIN. It has been exposed that, performance can be superior significantly when VC is used.

scholarly journals Symmetric-type dispersion maps in dispersion-managed optical link with mid-span spectral inversion

2020 ◽  
Vol 20 (1) ◽  
pp. 222
Author(s):  
Jea-Pil Chung ◽  
Seong-Real Lee
Keyword(s):  
Communication Systems ◽  
Group Velocity Dispersion ◽  
Phase Conjugation ◽  
Single Mode ◽  
Fiber Amplifier ◽  
Single Mode Fiber ◽  
Erbium Doped Fiber Amplifier ◽  
Optical Link ◽  
Optical Phase ◽  
Wavelength Division

In long-haul optical communication systems consisting of single-mode fiber spans and fiber amplifiers, such as an erbium-doped fiber amplifier, signal distortion causes performance to deteriorate because of group velocity dispersion and fiber nonlinearity. A combination of dispersion management and optical phase conjugation is an effective technique of compensating for the distortion. In an optical link configured with this combination, the dispersion map mainly affects the compensation for the distorted optical signals. Improvements in system performance have been reported for various types of dispersion maps. In this study, a symmetric type of dispersion map with respect to the midway optical phase conjugator is proposed. The effect of the proposed dispersion maps on the compensation for the distorted 24 channel × 40 Gbps wavelength-division-multiplexed signals was assessed through numerical simulation. It was confirmed that antipodal-type dispersion maps are most appropriate for the compensation, as well as for the flexibility of the link configuration.

Performance Enhancement of Encoding–Decoding Multidiagonal and Walsh Hadamard Codes for Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) Utilizing Dispersion Compensated Fiber

2020 ◽  
Vol 0 (0) ◽  
Author(s):  
Majidah H. Majeed ◽  
Riyadh Khlf Ahmed
Keyword(s):  
Multiple Access ◽  
Performance Enhancement ◽  
Optical Network ◽  
Spectral Amplitude ◽  
Q Factor ◽  
Data Traffic ◽  
Eye Diagram ◽  
Multiple User ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractSpectral Amplitude Coding-Optical Codes Division Multiple Access (SAC-OCDMA) is a future multiplexing technique that witnessed a dramatic attraction for eliminating the problems of the internet in optical network field such as multiple-user access and speed’s growth of the files or data traffic. In this research article, the performance of SAC-OCDMA system based on two encoding–decoding multidiagonal (MD) and Walsh Hadamard (WH) codes is enhanced utilizing three different schemes of dispersion compensating fiber (DCF): pre-, post- and symmetrical compensation. The system is simulated using Optisystem version 7.0 and Optigrating version 4.2. The performance of the proposed system is specified in terms of bit error rate (BER), Q-factor and eye diagram. It has been observed that the compensated system based on MD code is performs much better compared to the system based on WH code. On the other hand, the compensated SAC-OCDMA system with symmetrical DCF has the lowest values of BER and largest values of Q-factor, so it is considered the best simulated scheme contrasted with pre- and post-DCF.

A Novel Technique to Detect Code for SAC-OCDMA System

2018 ◽  
Vol 39 (2) ◽  
pp. 215-221 ◽  
Author(s):  
Manisha Bharti ◽  
Manoj Kumar ◽  
Ajay K. Sharma
Keyword(s):  
Multiple Access ◽  
Optical Power ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Main Task ◽  
Received Power ◽  
Performance Deterioration ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple ◽  
Detection Schemes

AbstractThe main task of optical code division multiple access (OCDMA) system is the detection of code used by a user in presence of multiple access interference (MAI). In this paper, new method of detection known as XOR subtraction detection for spectral amplitude coding OCDMA (SAC-OCDMA) based on double weight codes has been proposed and presented. As MAI is the main source of performance deterioration in OCDMA system, therefore, SAC technique is used in this paper to eliminate the effect of MAI up to a large extent. A comparative analysis is then made between the proposed scheme and other conventional detection schemes used like complimentary subtraction detection, AND subtraction detection and NAND subtraction detection. The system performance is characterized by Q-factor, BER and received optical power (ROP) with respect to input laser power and fiber length. The theoretical and simulation investigations reveal that the proposed detection technique provides better quality factor, security and received power in comparison to other conventional techniques. The wide opening of eye in case of proposed technique also proves its robustness.

Performance Analysis of Spectral Amplitude Coding Optical Code Division Multiple Access System using Modified Double Weight Codes with Adomian Decomposition Method

2018 ◽  
Vol 39 (4) ◽  
pp. 459-462 ◽  
Author(s):  
Monika Rani ◽  
Harbax Singh Bhatti ◽  
Vikramjeet Singh
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Decomposition Method ◽  
Adomian Decomposition Method ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Adomian Decomposition ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple ◽  
Multiple Access System

Abstract In this manuscript, we have analyzed a Spectral Amplitude Coding-Optical Code Division Multiple Access (SAC-OCDMA) System. The system performance is enhanced by reducing the effect of Multiple Access Interference (MAI) using uniform Fiber Bragg Gratings (FBGs) encoders and decoders at central office and subscriber’s end. The results are verified through a mathematical model and Modified Double Weight (MDW) codes for the proposed system using Adomian Decomposition Method (ADM). Further, we have demonstrated SAC-OCDMA system for transmission of 40 Gbps data rate up to a distance of 80 km by increasing the number of FBGs. The proposed system has been analyzed in terms of distance, bit error rate (BER) and Quality Factor.

Unified KS-Code

2009 ◽  
pp. 1473-1479 ◽  
Author(s):  
M. K.A. Abdullah ◽  
S. A. Aljunid ◽  
M. D.A. Samad ◽  
S. B.A. Anas ◽  
R. K.Z. Sahbudin
Keyword(s):  
Multiple Access ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Service Guarantees ◽  
Narrow Bandwidth ◽  
Network Topologies ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Many codes have been proposed for optical CDMA system as discussed in Svetislav, Mari, Zoran, Kosti, and Titlebaum (1993), Salehi (1989), Liu and Tsao (2002), Maric, Moreno, and Corrada (1996), Wei and Ghafouri-Shiraz (2002), and Prucnal, Santoro, and Ting (1986). Optical code division multiple access (OCDMA) has been recognized as one of the most important technologies for supporting many users in shared media simultaneous, and in some cases can increase the transmission capacity of an optical fiber. OCDMA is an exciting developments in short haul optical networking because it can support both wide and narrow bandwidth applications on the same network, it connects large number of asynchronous users with low latency and jitter, and permits quality of service guarantees to be managed at the physical layer, offers robust signal security and has simplified network topologies. However, for improperly designed codes, the maximum number of simultaneous users and the performance of the system can be seriously limited by the multiple access interference (MAI) or crosstalk from other users. Another issue in OCDMA is how the coding is implemented. The beginning idea of OCDMA was restricted in time domain, in which the encoding/decoding could not been fully utilized in optical domain. Therefore a new coding in OCDMA has been introduced based on spectral encoding (Kavehrad & Zaccarin, 1995; Pearce & Aazhang, 1994; Smith, Blaikie, & Taylor, 1998; Wei & Ghafouri-Shiraz, 2002). The system, called Optical Spectrum CDMA, or OS-CDMA, has the advantage of using inexpensive optical sources, and simple direct detection receivers. In this article with an emphasis on the Spectral Amplitude Coding scheme, a new code known as Khazani-Syed (KS) code is introduced.

scholarly journals Multiple-Code Technique for Multi-Rate Transmissions in Optical Packet Switching Networks Based on OCDMA Labels

Photonics ◽  
2019 ◽  
Vol 6 (2) ◽  
pp. 60 ◽  
Author(s):  
Kai-Sheng Chen
Keyword(s):  
Multiple Access ◽  
Packet Switching ◽  
Multiple Access Interference ◽  
Optical Packet Switching ◽  
Spectral Amplitude ◽  
Multiple Data ◽  
Rate Transmission ◽  
Multiple Code ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

Supporting multi-rate transmission is an essential factor in current optical packet switching (OPS) networks. In this paper, the author studied a multi-rate scheme capable of forwarding packets with different signal rates based on label switching. The multiple-code (MC) technique was employed to label a packet by conveying its payload bits to multiple optical code-division multiple-access (OCDMA) labels. Spectral-amplitude-coding (SAC), which represents the chips in an OCDMA code as a set of wavelengths, was introduced to remove the multiple-access interference (MAI) from the overlapping among labels. The author tested the system effectiveness by conducting numerical analysis to formulate bit-error probability (BEP) and spectral efficiency (SE). The simulation results showed that the proposed network had a stable BEP performance when switching the packet flows of multiple data-rates.

scholarly journals Packet Switching Strategy and Node Architecture of Extended Spectral-Amplitude-Coding Labels in GMPLS Networks

2019 ◽  
Vol 9 (7) ◽  
pp. 1513
Author(s):  
Kai-Sheng Chen
Keyword(s):  
Wavelength Division Multiplexing ◽  
Multiple Access ◽  
Packet Switching ◽  
Multiple Access Interference ◽  
Spectral Amplitude ◽  
Network Nodes ◽  
Wavelength Division ◽  
Node Architecture ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

We present packet switching applications based on extended spectral-amplitude-coding (SAC) labels in generalized multi-protocol label switching (GMPLS) networks. The proposed approach combines the advantages of wavelength-division multiplexing (WDM) and optical code-division multiple access (OCDMA). The extended SAC labels preserve the orthogonal property to avoid the effect of multiple access interference (MAI) shown at the decoder. We investigate the node architecture of label generation/recognition based on arrayed waveguide grating (AWG). Combining cyclic-shifted maximal length sequence (MLS) codes with the wavelength routed property of AWG simplifies the node structure. The simulation results show that the proposed labels achieve good performances against receiver noise due to the low average cross-correlation values. Under a given bit-error-rate (BER), the switching efficiency of the extended SAC labels outperforms the previous OCDMA schemes, as the network nodes are capable of processing a large number of labels simultaneously.

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