scholarly journals ACO-Based Multi-User Detection in Cooperative CDMA Networks

2011 ◽  
Vol 1 (2) ◽  
Author(s):  
Ali Jafarnia Jahromi ◽  
Mohammad T. Abdizadeh
Keyword(s):  
Computational Complexity ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Cooperative Diversity ◽  
Multiple Access Interference ◽  
Base Station ◽  
Relay Nodes ◽  
Cdma Networks ◽  
Code Division Multiple ◽  
Detector Simulation

In this paper, the cooperative diversity is investigated in the uplink of a Code Division Multiple Access (CDMA) network in which users cooperate by relaying each other’s messages toward the Base Station (BS). It is assumed that the spreading waveforms are not orthogonal and hence, Multiple Access Interference (MAI) exists at the relay nodes as well as the BS. MAI degrades the signal quality at both relays and BS and decreases the cooperative diversity gain. To alleviate this problem, an Ant Colony Optimization (ACO) based Multi-User Detector (MUD) has been proposed to efficiently combine the received signals from the direct and relay paths and sub-optimally extract transmitted bits at the BS. The computational complexity of proposed algorithm is significantly lower than that of the Maximum Likelihood (ML) detector. More explicitly, for a cooperative network supporting 15 users, the computational complexity of the proposed ACO algorithm is a factor of 103 lower than that of the optimum Bayesian detector. Simulation results show that the performance of the proposed ACO-based detector can closely approach the maximum diversity in terms of BER and efficiently cancel the MAI at the BS.

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.

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 A proposed method for determination of weighted despreading sequences for a DS/CDMA system

2007 ◽  
Vol 3 (3) ◽  
Author(s):  
Younes Jabrane ◽  
Radouane Iqdour ◽  
Brahim Ait Es Said ◽  
Najib Naja
Keyword(s):  
Interference Cancellation ◽  
Fuzzy Systems ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Additive White Gaussian Noise ◽  
Multiple Access Interference ◽  
Code Division Multiple ◽  
Parameter Values ◽  
Gaussian Noise Channels

The steeping chip weighting waveforms are used in multiple access interference cancellation by emphasizing the received spreading signal, therefore, that allows to solve the problem of orthogonality for the chip waveforms. Our paper presents a useful method based on fuzzy systems to determine the despreading sequences weighted by the steeping chip weighting waveforms for Direct Sequence Code Division Multiple Access DS/CDMA. The validity of our proposed method has been tested by numerical examples for an Additive White Gaussian Noise channels and shows that the parameter values of the chip weighting waveforms are good and the Bit Error Rate performance of the system does not undergone any degradation.

The CDMA Spread-Spectrum Cell Mobile Communication Uplink System with Cooperative Diversity

2014 ◽  
Vol 989-994 ◽  
pp. 3540-3543
Author(s):  
Han Cheng Liao
Keyword(s):  
Spread Spectrum ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Cooperative Diversity ◽  
Mobile Terminal ◽  
Spatial Diversity ◽  
Access System ◽  
Cooperative Scheme ◽  
Code Division Multiple ◽  
Multiple Access System

In this paper, physical layer cooperative communication of code division multiple access system is explored. Many mobile terminals relay signals for each other so as to achieve spatial diversity. The cooperative scheme of the mobile terminal is well designed. The uplink system model, as well as the receiving structure is given. The performance advantage of such system is clearly indicated through simulation.

Simulation of CDMA System Used in 3G Mobile Communication Based on Communication Materials

2012 ◽  
Vol 460 ◽  
pp. 70-73
Author(s):  
Bing Gang Xiao ◽  
Zhi Yi Xie ◽  
Peng Ye
Keyword(s):  
Communication Technology ◽  
Mobile Communication ◽  
Code Division Multiple Access ◽  
Multiple Access ◽  
Simulation Method ◽  
Base Station ◽  
Cdma System ◽  
Theoretical Conclusion ◽  
Whole Process ◽  
Code Division Multiple

CDMA is the abbreviation of Code Division Multiple Access which is a kind of new and mature wireless communication technology. The CDMA system Used in 3G mobile communication is simulated using the MATLAB software here. A CDMA2000 base station transmitter is established using the Simulink tools. Each module is initialized in order to achieve the simulation of a base station transmitter of the cdma2000. The whole process of producing singals is simulated by the fundamental reverse channel. The simulation results are compared with theoretical conclusion, proving that the simulation method is very effective.

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