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Interference Characterization and Suppression for Multiuser Direct-sequence Spread-spectrum System

Interference Characterization and Suppression for Multiuser Direct-sequence Spread-spectrum System PDF Author: Mingxi Fan
Publisher:
ISBN:
Category :
Languages : en
Pages : 184

Book Description
In this thesis we investigate efficient modulation and detection techniques for the uplink (i.e. transmission from mobile to base station) of a DS-CDMA network. Specifically, the thesis contains three parts. In the first part, we focus on the mobile transmitter. In particular, we evaluate and compare the spectral efficiency of two promising variable rate DS-CDMA transmission techniques, multicode (MCD) and variable-spreading-gain (VSG), under the presence of multiple-access (user-to-user) interferences (MAI) and multipath interferences. The uniqueness of our study is that in bit-error-rate evaluation, instead of approximating the interference as Gaussian noise (which has been done in most of the previous studies), we incorporate both power and distribution of interferences into consideration. We show where the Gaussian assumption may give misleading answers and how our results in these cases are different from those obtained in the past. In part two and three of the thesis, we focus on the base station receiver. Specifically, we present effective joint detection techniques that have good performance-complexity tradeoff. Part two of the thesis introduces a class of novel multistage parallel interference cancellation algorithms based on stage-by-stage minimum mean-squared error (MMSE) optimization. We show that this scheme is capable of achieving significantly better performance than other algorithms with similar complexity. Part three of the thesis presents a low-complexity dual-mode multiuser detector that dynamically switches its detection mode between the matched-filter receiver and the decorrelator. We show that this detector is capable of achieving the performance of a decorrelator but with significant savings in processing power and complexity.

Interference Characterization and Suppression for Multiuser Direct-sequence Spread-spectrum System

Interference Characterization and Suppression for Multiuser Direct-sequence Spread-spectrum System PDF Author: Mingxi Fan
Publisher:
ISBN:
Category :
Languages : en
Pages : 184

Book Description
In this thesis we investigate efficient modulation and detection techniques for the uplink (i.e. transmission from mobile to base station) of a DS-CDMA network. Specifically, the thesis contains three parts. In the first part, we focus on the mobile transmitter. In particular, we evaluate and compare the spectral efficiency of two promising variable rate DS-CDMA transmission techniques, multicode (MCD) and variable-spreading-gain (VSG), under the presence of multiple-access (user-to-user) interferences (MAI) and multipath interferences. The uniqueness of our study is that in bit-error-rate evaluation, instead of approximating the interference as Gaussian noise (which has been done in most of the previous studies), we incorporate both power and distribution of interferences into consideration. We show where the Gaussian assumption may give misleading answers and how our results in these cases are different from those obtained in the past. In part two and three of the thesis, we focus on the base station receiver. Specifically, we present effective joint detection techniques that have good performance-complexity tradeoff. Part two of the thesis introduces a class of novel multistage parallel interference cancellation algorithms based on stage-by-stage minimum mean-squared error (MMSE) optimization. We show that this scheme is capable of achieving significantly better performance than other algorithms with similar complexity. Part three of the thesis presents a low-complexity dual-mode multiuser detector that dynamically switches its detection mode between the matched-filter receiver and the decorrelator. We show that this detector is capable of achieving the performance of a decorrelator but with significant savings in processing power and complexity.

Multiple Access Interference Characterization for Direct-Sequence Spread-Spectrum Communications Using Chip Waveform Shaping

Multiple Access Interference Characterization for Direct-Sequence Spread-Spectrum Communications Using Chip Waveform Shaping PDF Author: Matthew G. Glen
Publisher:
ISBN: 9781423519928
Category : Coding theory
Languages : en
Pages : 78

Book Description
This research characterizes MAI effects on DS/SSMA system performance through simulation in Matlab , and explores the impact of multiple access code selection, chip waveform shaping, and multiple access code length on BER for both synchronous and asynchronous multiple access networks. In addition, the simulated DS/SSMA model permits rapid research into the effects of additional factors on BER. Prior to experimental testing, model validation is conducted through single user trials and by comparison with existing research for similar system designs. For synchronous and asynchronous networks, Gold coding improves BER by 7.5 and 4.0 dB, respectively, relative to aperiodic random spreading codes. Synchronous network results show that chip waveform shaping provides no significant BER improvement for the Blackman or Lanczos shapes. However, asynchronous network results show a potential BER improvement for Blackman and Lanczos shapes. Increasing code length from 31 to 511 resulted in a 7.5 dB BER improvement. Collectively, these results directly relate changes in BER to waveform cross-correlation statistics.

Interference Analysis and Reduction for Wireless Systems

Interference Analysis and Reduction for Wireless Systems PDF Author: Peter Stavroulakis
Publisher: Artech House
ISBN: 9781580535748
Category : Computers
Languages : en
Pages : 442

Book Description
This leading-edge resource offers you a new methodology for analyzing and studying the behavior of wireless communication systems in an interference environment. It provides you with modern tools and techniques for use in real-world applications that help you guarantee optimum system performance. The book treats both additive and multiplicative interfering signals, including in-depth descriptions of how these signals behave, regardless of the source.

Narrowband and Multiple-Access Interference Suppression for Direct Sequence Spread Spectrum Communication Receivers

Narrowband and Multiple-Access Interference Suppression for Direct Sequence Spread Spectrum Communication Receivers PDF Author:
Publisher:
ISBN:
Category :
Languages : en
Pages : 0

Book Description
This report presents research results focused on the mitigation of both narrowband and multiple access interference in direct sequence spread spectrum communication systems. Both linear and nonlinear adaptive algorithmic approaches are developed and reported. Specific attention has been paid to making the algorithmic practicable. In addition to the algorithmic development, a software simulation for a code division multiple access system is developed using a commercially available programming environment.

Multiuser Detection

Multiuser Detection PDF Author: Sergio VerdĂș
Publisher: Cambridge University Press
ISBN: 9780521593731
Category : Computers
Languages : en
Pages : 478

Book Description
Originally published in 1998, Multiuser Detection provides a comprehensive treatment of the subject of multiuser digital communications.

Improved Statistical Interference Suppression Techniques in Single and Multi-rate Direct Sequence Spread Spectrum Code Division Multiple Access Systems

Improved Statistical Interference Suppression Techniques in Single and Multi-rate Direct Sequence Spread Spectrum Code Division Multiple Access Systems PDF Author: Beibei Wang
Publisher:
ISBN: 9789072151094
Category :
Languages : en
Pages : 280

Book Description
We first present a statistical parallel interference cancellation (STPIC) technique. Here we propose two different methods: instantaneous STPIC (ISTPIC), in which IC is performed only on the bits whose absolute log likelihood ratio (LLR) is below a pre-selected threshold, and block STPIC (BSTPIC), in which IC is performed only on the blocks whose average signal-to-interference-plus-noise-ratio (SINR) is below a pre-selected threshold. Both LLR and SINR statistics reduce to quantities simple to obtain. It has been shown that both ISTPIC and BSTPIC can achieve performance similar to or better than conventional full PIC (FPIC), but with significantly reduced computational complexity. It is also shown that the proposed ISTPIC has larger performance gain than conventional FPIC in higher loading case where efficient interference cancellation techniques are mostly needed. We also propose a new generalized soft limiter (GSL) that combines the advantage of hard decision and partial soft decision. In GSL, hard decisions are made on "reliable" signals with absolute amplitudes larger than a threshold, whereas partial soft decisions are made on "unreliable" signals with absolute amplitudes less than the threshold. We have shown that PIC using the proposed GSL has performance similar to that using hyperbolic tangent decision, which has been shown to be the optimal decision in the single user case with Gaussian interference and noise, but with easier implementation. Furthermore, we propose new techniques that combine the STPIC with partial PIC or other improved decision techniques, which have shown to be capable of achieving performance similar to or better than original techniques with reduced computational complexity. We also evaluate and compare the performance of different PIC techniques in the presence of imperfect channel estimation and near-far effects. Performance analysis and comparison of different PIC techniques have also been done in multi-rate DS-CDMA systems with different schemes: variable spreading gain, multi-code, and variable chip rate. Finally, we review narrowband interference (NBI) suppression techniques and investigate the performance of a decision feedback scheme aided by the proposed GSL-PIC in the presence of NBI.

Performance Analysis of Interference Suppression Techniques for Multiple Antenna Systems

Performance Analysis of Interference Suppression Techniques for Multiple Antenna Systems PDF Author: Patrick Amihood
Publisher:
ISBN:
Category :
Languages : en
Pages : 135

Book Description
Finally, we consider the effects of channel estimation errors on the performance of a system employing Tomlinson-Harashima precoding and the QR decomposition, operating over MISO frequency-flat fading channels with decentralized receivers. The QR decomposition of the channel matrix is employed to arrive at an equivalent channel where successive interference cancellation at the transmitter can be used to remove the effect of the multiuser interference.

Narrowband Interference Suppression Techniques Using Decision Feedback Filtering in Direct Sequence Spread Spectrum Systems

Narrowband Interference Suppression Techniques Using Decision Feedback Filtering in Direct Sequence Spread Spectrum Systems PDF Author: Katherine Jauregui Lovette
Publisher:
ISBN:
Category :
Languages : en
Pages : 108

Book Description


Advanced Wireless Communications

Advanced Wireless Communications PDF Author: Savo G. Glisic
Publisher: John Wiley & Sons
ISBN: 9780470512876
Category : Technology & Engineering
Languages : en
Pages : 890

Book Description
Fully revised and updated version of the successful "AdvancedWireless Communications" Wireless communications continue to attract the attention ofboth research community and industry. Since the first edition waspublished significant research and industry activities have broughtthe fourth generation (4G) of wireless communications systemscloser to implementation and standardization. "Advanced Wireless Communications" continues to provide acomparative study of enabling technologies for 4G. This secondedition has been revised and updated and now includes additionalinformation on the components of common air interface, includingthe area of space time coding , multicarrier modulation especiallyOFDM, MIMO, cognitive radio and cooperative transmission. Ideal for students and engineers in research and development inthe field of wireless communications, the second edition ofAdvanced Wireless Communications also gives an understanding tocurrent approaches for engineers in telecomm operators, governmentand regulatory institutions. New features include: Brand new chapter covering linear precoding in MIMO channelsbased on convex optimization theory. Material based on game theory modelling encompassing problemsof adjacent cell interference, flexible spectra sharing andcooperation between the nodes in ad hoc networks. Presents and discusses the latest schemes for interferencesuppression in ultra wide band (UWB) cognitive systems. Discusses the cooperative transmission and more details onpositioning.

Principles of Spread-Spectrum Communication Systems

Principles of Spread-Spectrum Communication Systems PDF Author: Don Torrieri
Publisher: Springer Nature
ISBN: 3030753433
Category : Technology & Engineering
Languages : en
Pages : 715

Book Description
This textbook, now in its 5th edition, provides updated state-of-the-art coverage of spread-spectrum communication systems with new applications throughout the book. In this edition, the author extends sections with more comprehensive details about many topics. Some of the more complex sections have been rewritten to make them easier to understand. New subsections, sections, figures, and problems have been added throughout the book. New or expanded topics include frequency-hopping systems with multisymbol CPFSK detection, derivations of spread-spectrum systems with differential data modulations, chaotic systems, channel-state information, and MIMO. As with previous edition, the author presents mathematical analyses of spread-spectrum systems that provide insights into their operations and limitations and are of theoretical and practical interest to both researchers and system designers. He includes updated problems at the end of each chapter, which are intended to assist readers in consolidating their knowledge and to give practice in analytical techniques. Eight appendices provide the mathematical tools that are useful in understanding the main text.