scholarly journals Spectral Amplitude Coding Optical CDMA: Performance Analysis on Free Space Optical Channel

2018 ◽  
Vol 7 (4.38) ◽  
pp. 31
Author(s):  
Kehkashan A. Memon ◽  
A. W. Umrani ◽  
M. A. Unar ◽  
Wajiha Shah ◽  
B. S. Chowdhry
Keyword(s):  
Performance Analysis ◽  
Free Space ◽  
Optical Filters ◽  
Optical Cdma ◽  
Optical Channel ◽  
Spectral Amplitude ◽  
Free Space Optical ◽  
Spectral Amplitude Coding ◽  
Point To Point ◽  
Code Division Multiple

In this paper, we investigate the performance of Spectral Amplitude Coding Optical Code Division Multiple Access technique based on Free Space Optical channel. SAC OCDMA is one of the most popular multiplexing techniques since many years and FSO is gaining popularity and is very useful especially in point to point communication. The system presented in this paper utilizes Walsh Hadamard code as signature code. The coder and decoder structures are based on optical filters of fiber Bragg gratings (FBGs). This system focuses on the performance analysis of FSO based systems for subtropical regions. This paper demonstrates the error rate performance in the form of eye diagrams/BER under varying channel gain and link distances. Five cases have been taken which shows that SAC OCDMA FSO system is reliable even for distances sufficient to overcome the last mile problem.  

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.

A Review on Successive Interference Cancellation Scheme Based on Optical CDMA Network

2014 ◽  
Vol 35 (4) ◽  
Author(s):  
N. Alsowaidi ◽  
T. Eltaif ◽  
M. R. Mokhtar
Keyword(s):  
Interference Cancellation ◽  
Multiple Access ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Successive Interference Cancellation ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Cdma System ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractDue to various desirable features of optical code division multiple access (OCDMA), it is believed this technique once developed and commercially available will be an integral part of optical access networks. Optical CDMA system suffers from a problem called multiple access interference (MAI) which limits the number of active users, it occurs when number of active users share the same carriers. The aim of this paper is to review successive interference cancellation (SIC) scheme based on optical CDMA system. The paper also reviews the system performance in presence of shot noise, thermal noise, and phase–induced intensity noise (PIIN). A comprehensive review on the mathematical model of SIC scheme using direct detection (DS) and spectral amplitude coding (SAC) were presented in this article.

scholarly journals Noncoherent Spectral Optical CDMA System Using 1D Active Weight Two-Code Keying Codes

2016 ◽  
Vol 2016 ◽  
pp. 1-9
Author(s):  
Bih-Chyun Yeh
Keyword(s):  
Cross Correlation ◽  
Transfer Functions ◽  
Block Design ◽  
Optical Network ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Source Power ◽  
New Family ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

We propose a new family of one-dimensional (1D) active weight two-code keying (TCK) in spectral amplitude coding (SAC) optical code division multiple access (OCDMA) networks. We use encoding and decoding transfer functions to operate the 1D active weight TCK. The proposed structure includes an optical line terminal (OLT) and optical network units (ONUs) to produce the encoding and decoding codes of the proposed OLT and ONUs, respectively. The proposed ONU uses the modified cross-correlation to remove interferences from other simultaneous users, that is, the multiuser interference (MUI). When the phase-induced intensity noise (PIIN) is the most important noise, the modified cross-correlation suppresses the PIIN. In the numerical results, we find that the bit error rate (BER) for the proposed system using the 1D active weight TCK codes outperforms that for two other systems using the 1D M-Seq codes and 1D balanced incomplete block design (BIBD) codes. The effective source power for the proposed system can achieve −10 dBm, which has less power than that for the other systems.

Performance Evaluation of System in Free Space Optic Utilizing Gaussian Optical Filter in Different Detection Scheme

2019 ◽  
Vol 41 (1) ◽  
pp. 31-36
Author(s):  
H. Djellab ◽  
A. Bouarfa ◽  
S. Bojanic
Keyword(s):  
Wavelength Division Multiplexing ◽  
Free Space ◽  
Direct Detection ◽  
Optical Filter ◽  
Weather Conditions ◽  
Spectral Amplitude ◽  
Free Space Optical ◽  
Detection Scheme ◽  
High Data ◽  
Code Division Multiple

Abstract In recent years, free space optical communication (FSO) has become a leader for its unique characteristics: large bandwidth, unlicensed spectrum, simple implementation, low power and high data rate. However, we use as a transmission medium for Spectral Amplitude Coding-Optical Code Division Multiple Access SAC OCDMA system. In this paper, we investigate the optimum received power of FSO communication system employing SAC OCDMA, by using different detection technique, such us Spectral Direct Detection SDD and Single Photodiode Detection (SPD) technique under optical Gaussian filter decoder schemes with Modified Double Weight code (MDW). In this work, the adverse effects of atmospheric channel limit the possibility of a large FSO communication, moderate turbulence and hazy weather conditions are considered. The results show that the performance of the proposed system with wavelength-division-multiplexing (WDM) multiplexer (MUX) based on Gaussian optical filter with SDP detection fares better than the system employing SDD technique.

Performance analysis of spectral-amplitude-coding optical CDMA systems with new subtract exclusive OR detection (SED) using vectors combinatorial (VC) code

Optik ◽  
2012 ◽  
Vol 123 (15) ◽  
pp. 1352-1359 ◽  
Author(s):  
Hassan Yousif Ahmed ◽  
M. Almaleeh ◽  
Hilal Fadhil ◽  
S.A. Aljunid ◽  
Ammar Elyass ◽  
...  
Keyword(s):  
Performance Analysis ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Cdma Systems ◽  
Spectral Amplitude Coding ◽  
Exclusive Or

A Review on Spectral Amplitude Coding Optical Code Division Multiple Access

2017 ◽  
Vol 38 (1) ◽  
Author(s):  
Navpreet Kaur ◽  
Rakesh Goyal ◽  
Monika Rani
Keyword(s):  
Code Division Multiple Access ◽  
Multiple Access ◽  
Noise Source ◽  
Direct Detection ◽  
Multiple Access Interference ◽  
Optical Cdma ◽  
Spectral Amplitude ◽  
Correlation Property ◽  
Spectral Amplitude Coding ◽  
Code Division Multiple

AbstractThis manuscript deals with analysis of Spectral Amplitude Coding Optical Code Division Multiple Access (SACOCDMA) system. The major noise source in optical CDMA is co-channel interference from other users known as multiple access interference (MAI). The system performance in terms of bit error rate (BER) degrades as a result of increased MAI. It is perceived that number of users and type of codes used for optical system directly decide the performance of system. MAI can be restricted by efficient designing of optical codes and implementing them with unique architecture to accommodate more number of users. Hence, it is a necessity to design a technique like spectral direct detection (SDD) technique with modified double weight code, which can provide better cardinality and good correlation property.

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