Performance Analysis and Simulation of a Direct Sequence CDMA System for Various Spreading Sequences PDF Download
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Author: Girish-Kumar K. N.
Publisher:
ISBN:
Category : Code division multiple access
Languages : en
Pages : 192
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Author: Girish-Kumar K. N.
Publisher:
ISBN:
Category : Code division multiple access
Languages : en
Pages : 192
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Author: Marcelo Guillen
Publisher:
ISBN:
Category :
Languages : en
Pages : 216
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Author: Meher Krishna Patel
Publisher:
ISBN:
Category : Chaotic behavior in systems
Languages : en
Pages : 116
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Book Description
This thesis presents the analysis of chaos-based direct sequence code division multiple access (DS-CDMA) systems under imperfect channel estimation environments. Chaos-based CDMA systems are studied extensively in the last few decades, but their performances under imperfect channel estimation conditions are never studied. The main motivation of the thesis is to fill this research gap under various possible conditions. The thesis focuses on three main objectives. The first objective is to determine the effect of spreading sequences in channel estimation processes. Here performances of channel estimators in the presence and absence of chaotic spreading sequences are investigated. The second objective is to study the performances of imperfect channel estimations in chaos based CDMA systems under various fading conditions. This part mainly focuses on the various factors which deteriorate the performance of the systems. The third objective focuses on the various techniques which can improve the performances of the systems. In this part various available techniques for CDMA systems are studied under imperfect channel estimation environments. It is concluded that performances of all the available chaos based CDMA systems significantly depend on performances of channel estimators. Analytical simulation results in the thesis show that performance degradation in available systems due to various fading channels can be significantly improved by using channel estimators.
Author:
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ISBN:
Category :
Languages : en
Pages :
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Direct sequence-code division multiple access (DS-CDMA) technique is used in cellular systems where users in the cell are separated from each other with their unique spreading codes. In recent times DS-CDMA has been used extensively. These systems suffers from multiple access interference (MAI) due to other users transmitting in the cell, channel inter symbol interference (ISI) due to multipath nature of channels in presence of additive white Gaussian noise(AWGN). Spreading codes play an important role in multiple access capacity of DS-CDMA system. M-sequences, gold sequences etc., has been traditionally used as spreading codes in DS-CDMA. These sequences are generated by shift registers and periodic in nature. So these sequences are less in number and also limits the security. This thesis presents an investigation on use of new type of sequences called chaotic sequences for DS-CDMA system. These sequences are generated by chaotic maps. First of all, chaotic sequences are easy to generate and store. Only a few parameters and functions are needed even for very long sequences. In addition, an enormous number of different sequences can be generated simply by changing its initial condition. . Chaotic sequences are deterministic, reproducible, uncorrelated and random-like, which can be very helpful in enhancing the security of transmission in communication. This Thesis investigates the performance of chaotic sequences in DS-CDMA communication systems using various receiver techniques. Extensive simulation studies demonstrate the performance of the different linear and nonlinear DS-CDMA receivers like RAKE receiver, matched filter (MF) receiver, minimum mean square error (MMSE) receiver and Volterra receiver using chaotic sequences and the performance have been compared with gold sequences.
Author: Shuling Feng
Publisher:
ISBN:
Category : Code division multiple access
Languages : en
Pages : 310
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Author: Valentina Emilia Balas
Publisher: Springer
ISBN: 9783319387871
Category : Technology & Engineering
Languages : en
Pages : 0
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This volume includes the proceedings of the 2015 International Conference on Information Technology and Intelligent Transportation Systems (ITITS 2015) which was held in Xi’an on December 12-13, 2015. The conference provided a platform for all professionals and researchers from industry and academia to present and discuss recent advances in the field of Information Technology and Intelligent Transportation Systems. The presented information technologies are connected to intelligent transportation systems including wireless communication, computational technologies, floating car data/floating cellular data, sensing technologies, and video vehicle detection. The articles focusing on intelligent transport systems vary in the technologies applied, from basic management systems to more application systems including topics such as emergency vehicle notification systems, automatic road enforcement, collision avoidance systems and some cooperative systems. The conference hosted 12 invited speakers and over 200 participants. Each paper was under double peer reviewed by at least 3 reviewers. This proceedings are sponsored by Shaanxi Computer Society and co-sponsored by Chang’an University, Xi’an University of Technology, Northwestern Poly-technical University, CAS, Shaanxi Sirui Industries Co., LTD.
Author: Weimin Xiao
Publisher:
ISBN:
Category :
Languages : en
Pages :
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The performance of linear filtering is studied for the suppression of multiple access interference in a Direct-Sequence Code-Division Multiple Access (DS-CDMA) system with random spreading sequences. Both full-rank and reduced-rank filters are investigated. The emphasis of our study is on large system performance analysis.
Author: Khaled Fazel
Publisher: Springer Science & Business Media
ISBN: 940170502X
Category : Technology & Engineering
Languages : en
Pages : 515
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The benefits and success of multi-carrier (MC) modulation on one side and the flexibility offered by the spread spectrum (SS) technique on the other side have motivated many researchers to investigate the combination of both techniques since 1993. This combination known as multi-carrier spread spectrum (MC-SS) benefits from the advantages of both systems and offers high flexibility, high spectral efficiency, simple detection strategies, narrow-band interference rejection capability, etc. The basic principle of this combination is straightforward: The spreading is performed as direct sequence spread spectrum (DS-SS) but instead of transmitting the chips over a single carrier, several sub-carriers are employed. The MC modulation and demodulation can easily be realized in the digital domain by performing IFFT and FFT operations. The separation of the users' signals can be performed in the code domain. MC-SS systems can perform the spreading in frequency direction, which allows for simple signal detection strategies. Since 1993, MC-SS has been deeply studied and new alternative solutions have been proposed. Meanwhile, deep system analysis and comparison with DS-CDMA have been performed that show the superiority of MC-CDMA.
Author:
Publisher:
ISBN:
Category :
Languages : en
Pages :
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Book Description
Direct sequence-code division multiple access (DS-CDMA) technique is used in cellular systems where users in the cell are separated from each other with their unique spreading codes. In recent times DS-CDMA has been used extensively. These systems suffers from multiple access interference (MAI) due to other users transmitting in the cell, channel inter symbol interference (ISI) due to multipath nature of channels in presence of additive white Gaussian noise(AWGN). Spreading codes play an important role in multiple access capacity of DS-CDMA system. M-sequences, gold sequences etc., has been traditionally used as spreading codes in DS-CDMA. These sequences are generated by shift registers and periodic in nature. So these sequences are less in number and also limits the security. This thesis presents an investigation on use of new type of DS CDMA receiver called Genetic Algorithm based DS-CDMA receiver. Genetic Algorithm is robust optimization technique and does not fall into local minima hence this gives better weight optimization of any system. This Thesis investigates the performance of GA based DS-CDMA communication using gold code sequences. Extensive simulation studies demonstrate the performance of the different linear and nonlinear DS-CDMA receivers like RAKE receiver, matched filter (MF) receiver, minimum mean square error (MMSE) receiver using gold sequences and the performance have been compared with GA based receiver.
Author: 劉清平
Publisher:
ISBN:
Category :
Languages : en
Pages :
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