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Author : Steven John Baines
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (535 download)
Download or read book Linear Multi-user Detection in DS-CDMA Cellular Systems written by Steven John Baines and published by . This book was released on 1997 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Jinwen Ma
Publisher :
ISBN 13 :
Total Pages : 190 pages
Book Rating : 4.:/5 (485 download)
Download or read book Multi-user Detection for Multi-rate DS/CDMA Systems written by Jinwen Ma and published by . This book was released on 2000 with total page 190 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless cellular communication is witnessing a rapid growth in market, technology and range of services. Current and future demands for wireless communication services motivate the need for handling multi-media traffic types. In a multimedia communication system, users with different and even time-varying rates and quality of services (QoS) requirements, such as voice, image and data, must be accommodated. The use of Spread Spectrum modulation with Code Division Multiple Access (CDMA) technology is an attractive approach for economical spectrally efficient and high quality cellular and personal communication services. This dissertation explores the technologies of applying different interference cancellation techniques to multi-rate CDMA systems that serve users with different QoS. Multiple Access Interference (MAI) and multipath propagation are the major issues in wireless communication systems. It is also true for multi-rate CDMA systems. Multi-user detection has been shown to be effective in combating the near-far problem and providing superior performance over conventional detection method. In this dissertation, we combine both linear minimum mean squared error (LMMSE) detector, nonlinear decision feedback detector, with other signal processing techniques, such as array processing and multipath combining, to create effective near-far resistant detectors for multi-rate CDMA systems. Firstly, we propose MMSE receivers for synchronous multi-rate CDMA system and compare the performance with the corresponding multi-rate decorrelating detectors. The multi-rate decorrelating detector is optimally near-far resistant and easy to implement. The proposed linear MMSE multi-rate receiver can be adaptively implemented only with the knowledge of the desired user. Due to the fact that MMSE detector offers best trade-off between the MAI cancellation and noise variance enhancement, it is shown that multi-rate MMSE receiver can offer better performance than the multi-rate decorrelator when the interfering users' Signal to Noise Ratio (SNR) is relatively low comparing to the desired user's SNR. Secondly, the asynchronous multi-rate CDMA system, we propose multi-rate multi-shoot decorrelating detectors and multi-rate multi-shot MMSE detectors. The performance of multi-shot detectors can be improved monotonically with increasing the number of stacked bits, but a great computational complexity is going to be introduced in order to get better performance. A debiasing method is introduced to multi-rate multi-shot linear detectors. Debiasing method optimizes multi-rate detectors based on the multi-rate multi-shot model. Debiasing multi-shot MMSE detector for multi-rate signals can offer performance than the corresponding debiasing multi-shot decorrelating detector. Thirdly, we propose linear space-time receivers for multi-rate CDMA systems. The minimum mean-squared error criteria is used. We perform a comparative study on the multi-rate receiver which uses either multipath (temporal) processing or array (spatial) processing, and the one which uses both array and multipath (space-time) processing. The space-time receiver for the multi-rate CDMA signals give us the potential of improving the capacity of multi-rate systems. The space-time processing combined with multiuser detection have the advantages of combating multipath fading through temporal processing, reducing MAI through MMSE method and provide antenna or diversity gain through spatial processing and increasing the capacity of the multi-rate CDMA systems. Lastly, the group-wise interference cancellation methods are proposed for multi-rate CDMA signals. The non-linear decision feedback detection (DFD) schemes are used in the proposed receivers. The proposed interference cancellation schemes benefit from the nature of the unequal received amplitudes for multi-rate CDMA signals. Users with same data rate are grouped together. Users with the highest data-rate are detected first. Interference between the groups is cancelled in a successive order. The results show that the group-wise MMSE DFD yields better performance than multi-rate linear MMSE detector and multi-rate decorrelating detector, especially for highly loaded CDMA systems.
Author : Paulo Silva
Publisher : CRC Press
ISBN 13 : 1000794156
Total Pages : 264 pages
Book Rating : 4.0/5 (7 download)
Download or read book Frequency-Domain Multiuser Detection for CDMA Systems written by Paulo Silva and published by CRC Press. This book was released on 2022-09-01 with total page 264 pages. Available in PDF, EPUB and Kindle. Book excerpt: Future broadband wireless communication systems are expected to be able to offer new and powerful services enabling fast transmission rates of several tens of Mbit/s. This is an ambitious challenge especially for mobile communication systems since these systems should be able to cope with severely time dispersive channels, associated to the signal multipath propagation. Moreover, these systems should have high spectral and power efficiencies, as well as high capacity and flexibility. Spread spectrum techniques, particularly coded division multiple access (CDMA) techniques allow high capacity and flexibility, continuous transmission requiring low-peak power requirements for the amplifiers, as well as some robustness against fading and time-dispersion effects associated with the multipath propagation. When employed in prefix assisted (PA) block transmission schemes combined with frequency-domain receiver implementations they become especially interesting for broadband wireless systems. In Frequency-Domain Multiuser Detection for CDMA Systems the use of PA block transmission is considered in the context of both DS (Direct Sequence) and MC (Multicarrier) CDMA schemes. The main goal is the study of frequency-domain multiuser detection techniques with iterative signal detection/decoding techniques, also in combination with estimation and cancelation of nonlinear distortion effects. The receiver structures are suitable to scenarios with high interference levels and strongly time-dispersive channels.
Author : Piero Castoldi
Publisher : Artech House
ISBN 13 : 9781580538015
Total Pages : 256 pages
Book Rating : 4.5/5 (38 download)
Download or read book Multiuser Detection in CDMA Mobile Terminals written by Piero Castoldi and published by Artech House. This book was released on 2002 with total page 256 pages. Available in PDF, EPUB and Kindle. Book excerpt: Here's an authoritative, cutting-edge resource that gives you a thorough understanding of CDMA transmission and detection. It offers practical guidance in designing interference-reducing multi-user receivers for mobile radio systems and multi-user adaptive modems for accessing satellite earth stations. The book provides in-depth descriptions of CDMA principles, and of linear and non-linear multi-user detection , and covers the fine details of the realization of a linear multi-user receiver.
Author : Zhiwei Mao
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (988 download)
Download or read book Some Issues on Multiuser Detection in DS-CDMA Systems written by Zhiwei Mao and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, direct-sequence code-division multiple access (DS-CDMA) systemswith multiuser detectors used at receiver are investigated and two kinds of multiuser detectors are developed for DS-CDMA systems. In the investigation of DS-CDMA systems using multiuser detectors at receiver, a study on the performance of the system is presented, where heterogeneous traffic with different transmission rates and quality of service (QoS) requirements is supported. The effects of some realistic factors, such as imperfect power control and the existence of multiple cells, on the system performance are studied. In addition, algorithms are proposed to deal with the forward link power allocation problem based on the measurements of random characteristics of the received signals. This power allocation problem is formulated as a constrained optimization problem. To make the problem easy to solve, an additional appropriate constraint is proposed. Two methods are developed to identify the feasible region of this constrained optimization problem.The first proposed multiuser detector is an adaptive minimum mean-squared-error(MMSE) detector. Particularly, it is desirable for the cases where communication channelshave severe near-far problem, and thus the convergence rates of adaptive MMSE detectorsfor users with different power are quite different. To improve the convergence ratesof adaptive MMSE detectors for weak power users, the interference effects of the strongpower user signals are subtracted from the received signal successively. The method to estimatethe parameters required in the proposed detector is also developed. It is shown thatthe proposed detector achieves fast convergence rates in various near-far scenarios. Otherstudies conducted include the transient mean-squared-error (MSE) analysis to explain thedifferent convergence rates of adaptive MMSE detectors for users with different power, and the bit-error-rate (BER) performance analysis for the proposed detector. The second proposed multiuser detector is a set of semi-blind linear parallel interferencecancellation (PIC) detectors for the reverse link of multiple-cell systems, where only information about intra-cell users is available. To decrease the interference from inter-cellusers whose information is unavailable to the receiver, the inter-cell user signal subspace is identified first by making use of the available information about intra-cell users. The eigen vectors and eigen values of this signal subspace are then used in the traditional linear PIC structure, in place of the unknown inter-cell users' signature codes and signal amplitudes. Based on this idea, three detection schemes are proposed. In addition, an efficient adaptation implementation method is developed, and the performance of the proposed detectorsis studied. The proposed detectors are shown to be suitable for practical implementations and have satisfactory performance.
Author : R. Michael Buehrer
Publisher : Morgan & Claypool Publishers
ISBN 13 : 1598290401
Total Pages : 192 pages
Book Rating : 4.5/5 (982 download)
Download or read book Code Division Multiple Access (CDMA) written by R. Michael Buehrer and published by Morgan & Claypool Publishers. This book was released on 2006 with total page 192 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book covers the basic aspects of Code Division Multiple Access or CDMA. It begins with an introduction to the basic ideas behind fixed and random access systems in order to demonstrate the difference between CDMA and the more widely understood TDMA, FDMA or CSMA. Secondly, a review of basic spread spectrum techniques are presented which are used in CDMA systems including direct sequence, frequency-hopping and time-hopping approaches. The basic concept of CDMA is presented, followed by the four basic principles of CDMA systems that impact their performance: interference averaging, universal frequency reuse, soft handoff, and statistical multiplexing. The focus of the discussion will then shift to applications. The most common application of CDMA currently is cellular systems. A detailed discussion on cellular voice systems based on CDMA, specifically IS-95, is presented. The capacity of such systems will be examined as well as performance enhancement techniques such as coding and spatial filtering. Also discussed are Third Generation CDMA cellular systems and how they differ from Second Generation systems. A second application of CDMA that is covered is spread spectrum packet radio networks. Finally, there is an examination of multi-user detection and interference cancellation and how such techniques impact CDMA networks. This book should be of interest and value to engineers, advanced students, and researchers in communications.
Author : Mohsen Ghotbi
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (11 download)
Download or read book Multiuser Detection of DS-CDMA Signals Using Parallel Interference Cancellation in Wireless Communications written by Mohsen Ghotbi and published by . This book was released on 2001 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a limited network resource, techniques are needed to share the channel among different users as efficiently and as fairly as possible. Among multiple access techniques; Code Division Multiple Access (CDMA) has the exclusive advantage of allowing all active users share the same channel concurrently. When CDMA technique is used, Multi User Detection (MUD) is needed to reject or reduce the Multiple Access Interference (MAI) affecting each active user. In this thesis, it is shown that multiuser detection using Parallel Interference Cancellation (PIC) technique provides a good compromise among the complexity, latency, and performance. This technique is suitable for Digital Video Broadcasting-Return Channel via Satellite (DVB-RSC) as well as Base Station (BS) in cellular communication systems. We offer a new scheme that is a combination of soft and hard PIC detectors whose performance is superior to that of the other famous sub-optimal detectors. For most MUD schemes, a perfect knowledge of users' parameters is required. In this thesis, we apply a very simple method to estimate the parameters. PIC detectors are usually studied in equal-power case, i.e., a perfect power control scheme is assumed. We study PIC detector in near-far condition as well, where users arrive at receiver with different power levels. It is shown that our proposed scheme has some advantages over other schemes. First, it is much less complex than optimal and linear detectors. Second, it is much faster than sequential detector. Third, it has better performance than that of linear detectors.
Author : Liqing Zhang
Publisher :
ISBN 13 :
Total Pages : 370 pages
Book Rating : 4.:/5 (615 download)
Download or read book Multiuser Detection and Performance Evaluation for Cellular DS-CDMA Networks with Partial Information written by Liqing Zhang and published by . This book was released on 2003 with total page 370 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Peter Koon Pong Cheung
Publisher :
ISBN 13 :
Total Pages : 197 pages
Book Rating : 4.:/5 (222 download)
Download or read book Blind Linear Multiuser Detection for DS-CDMA Wireless Networks written by Peter Koon Pong Cheung and published by . This book was released on 1999 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Michael L. Honig
Publisher : John Wiley & Sons
ISBN 13 : 9780470473801
Total Pages : 512 pages
Book Rating : 4.4/5 (738 download)
Download or read book Advances in Multiuser Detection written by Michael L. Honig and published by John Wiley & Sons. This book was released on 2009-08-19 with total page 512 pages. Available in PDF, EPUB and Kindle. Book excerpt: A Timely Exploration of Multiuser Detection in Wireless Networks During the past decade, the design and development of current and emerging wireless systems have motivated many important advances in multiuser detection. This book fills an important need by providing a comprehensive overview of crucial recent developments that have occurred in this active research area. Each chapter is contributed by noted experts and is meant to serve as a self-contained treatment of the topic. Coverage includes: Linear and decision feedback methods Iterative multiuser detection and decoding Multiuser detection in the presence of channel impairments Performance analysis with random signatures and channels Joint detection methods for MIMO channels Interference avoidance methods at the transmitter Transmitter precoding methods for the MIMO downlink This book is an ideal entry point for exploring ongoing research in multiuser detection and for learning about the field's existing unsolved problems and issues. It is a valuable resource for researchers, engineers, and graduate students who are involved in the area of digital communications.
Author : CHRISTIAN SCHLEGEL
Publisher : Springer Science & Business Media
ISBN 13 : 140204075X
Total Pages : 282 pages
Book Rating : 4.4/5 (2 download)
Download or read book Coordinated Multiuser Communications written by CHRISTIAN SCHLEGEL and published by Springer Science & Business Media. This book was released on 2006-07-10 with total page 282 pages. Available in PDF, EPUB and Kindle. Book excerpt: Coordinated Multiuser Communications provides for the first time a unified treatment of multiuser detection and multiuser decoding in a single volume. Many communications systems, such as cellular mobile radio and wireless local area networks, are subject to multiple-access interference, caused by a multitude of users sharing a common transmission medium. The performance of receiver systems in such cases can be greatly improved by the application of joint detection and decoding methods. Multiuser detection and decoding not only improve system reliability and capacity, they also simplify the problem of resource allocation. Coordinated Multiuser Communications provides the reader with tools for the design and analysis of joint detection and joint decoding methods. These methods are developed within a unified framework of linear multiple-access channels, which includes code-division multiple-access, multiple antenna channels and orthogonal frequency division multiple access. Emphasis is placed on practical implementation aspects and modern iterative processing techniques for systems both with, and without integrated error control coding. Focusing on the theory and practice of unifying accessing and transmission aspects of communications, this book is a valuable reference for students, researchers and practicing engineers.
Author : Ping Liu
Publisher :
ISBN 13 :
Total Pages : 414 pages
Book Rating : 4.3/5 (121 download)
Download or read book Code-aided Multiuser Detection in Multiple Access Wireless Communication Systems written by Ping Liu and published by . This book was released on 2004 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Yishu Guo
Publisher :
ISBN 13 :
Total Pages : 0 pages
Book Rating : 4.:/5 (11 download)
Download or read book Combined Adaptive Multiuser Detection for DS-CDMA System written by Yishu Guo and published by . This book was released on 2003 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The inadequacy of the conventional Code Division Multiple Access (CDMA) receivers in a multiple access interference-limited mobile radio environment has spurred research on advanced receiver technologies. This research investigates the use of adaptive receivers for multi-user detection to overcome some of the deficiencies of a conventional receiver and, hence, suppress the multiple access interference (MAI) and narrow band interference (NBI) in DS/CDMA wireless systems. The MAI is a major factor influencing the communication quality and the capacity in CDMA wireless systems. Hence, suppression of MAI and NBI are essential for an efficient performance of a CDMA wireless system and to enhance the system capacity. Analysis of the conventional detector and minimum mean-squared error (MMSE) detector is carried out to provide a better understanding of the effect of the channel parameters on the performance of the detectors and to explain the near-far resilience of the receiver. The performance of these detectors are compared and analyzed. The derivation of the relationship between the minimum mean-squared error detector and minimum output energy (MOE) detector is developed in order to provide an adaptive implementation of the later. The limitation of the existing RLS blind algorithms for MMSE detector in AWGN channels is analyzed. In order to improve the performance of the existing schemes and to eliminate the requirement of training sequences, a scheme combining the blind adaptation and MAI cancellation is proposed. The performance of this algorithm is analyzed and compared with the existing schemes. Extensive simulations have been carried out to demonstrate that the proposed scheme is more reliable and it provides an effective resilience to the environment changes.
Author : D. Leonard Anair
Publisher :
ISBN 13 :
Total Pages : 196 pages
Book Rating : 4.E/5 ( download)
Download or read book Performance of Fixed and Adaptive Multi-user Linear Detectors for DS-CDMA Under Non-ideal Conditions a Software Package written by D. Leonard Anair and published by . This book was released on 1999 with total page 196 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Sang Gook Kim
Publisher :
ISBN 13 :
Total Pages : 18 pages
Book Rating : 4.:/5 (448 download)
Download or read book On the Use of Antenna Arrays and Multiuser Detection for DS/CDMA Systems written by Sang Gook Kim and published by . This book was released on 2000 with total page 18 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Author : Lajos L. Hanzo
Publisher : Wiley-IEEE Press
ISBN 13 : 9780470863091
Total Pages : 1104 pages
Book Rating : 4.8/5 (63 download)
Download or read book Single and Multi-Carrier DS-CDMA written by Lajos L. Hanzo and published by Wiley-IEEE Press. This book was released on 2003-09-26 with total page 1104 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume is dedicated to a range of CDMA and MC-CDMA transmission aspects of systems designed for communicating over fading wireless channels. Currently, a technical in-depth book on this subject, which has a similar detailed exposure of the recent advances in CDMA, M-ary CDMA and MC-CDMA, is unavailable. A further attraction of the joint treatment of these topics is that it allows the reader to view their design trade-offs in a comparative context. Divided into five main parts: Part I: provides a detailed introduction to the subject of CDMA systems designed for employment in various application Part II: deals with the currently hot topic of genetic algorithm assisted multiuser detection Part III: gives a detailed account of new, reduced-complexity M-ary CDMA schemes Part IV: considers a range of novel MC-CDMA schemes which have the potential of supporting numerous design objectives Part V: provides an overview of the 3G wireless system proposals and characterises the expected network capacity gains attained with the aid of adaptive CDMA systems By providing an all-encompassing self-contained treatment this groundbreaking volume will have appeal to researchers, postgraduate students, academics practising research and development engineers working for wireless communications and computer networking companies, as well as senior undergraduate students and technical managers in the field.
Author : Xianmin Wang (Ph. D.)
Publisher :
ISBN 13 :
Total Pages : pages
Book Rating : 4.:/5 (119 download)
Download or read book Multiuser detection for DS-CDMA systems using optimization methods written by Xianmin Wang (Ph. D.) and published by . This book was released on 2004 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Several new multiuser detectors are developed for different direct-sequence codedivision multiple-access (DS-CDMA) application environments. The first detector is based on a semidefinite-programming (SDP) relaxation technique. In this detector, maximum likelihood (ML) detection is achieved by 'relaxing' the associated combinatorial problem into an SDP problem, which leads to a detector of polynomial complexity. It is shown that the SDP-relaxation (SDPR) based detector can be obtained by solving a dual SDP problem which leads to improved efficiency. Computer simulations demonstrate that the SDPR detector offers near-optimal performance with much reduced computational complexity compared with that of the ML detector proposed by Verdu for both synchronous and asynchronous DS-CDMA systems. The second detector is based on a recursive convex programming (RCP) approach. In this detector, ML detection is carried out in two steps: first, the combinatorial problem associated with ML detection is relaxed to a convex programming problem, and then a recursive approach is used to obtain an approximate solution for ML detection. Efficient unconstrained relaxation approach is proposed for the proposed detector to reduce the involved computational complexity. Computer simulations demonstrate that the proposed detectors offer near-optimal detection performance which is superior to that offered by many other suboptimal detectors including the SDPR detector. However, the computational complexity involved in the proposed detectors is much lower relative to that involved in Verdu's ML detector as well as our SDPR detector. The third detector entails a subspace estimation-based constrained optimization approach for channel estimation in DS-CDMA systems with multipath propagation channels. The proposed approach offers an improved approximation for the noise iii subspace compared with that offered by several existing algorithms. Computer simulations show that the performance of the proposed detector offers nearly the same performance as that of existing subspace detectors but leads to a significant reduction in the amount of computation. Relative to some existing constrained optimization methods, the proposed detector offers a significantly improved performance while requiring a comparable amount of computation. The fourth detector is proposed based on a vector constant-modulus (VCM) approach. This detector is designed for DS-CDMA systems with multipath propagation channels where the effective signatures observed at receiver are distorted by multipath propagation and aliasing concurrently. In this detector, detection is carried out by solving a linear constrained optimization problem whose objective function is formulated based on the VCM criterion. Two adaptation algorithms, namely, the constrained stochastic gradient algorithm and the recursive vector constant-modulus algorithm, are developed. Analysis are presented to investigate the performance of the proposed detector. Computer simulations show that the proposed detectors are able to suppress multiuser interference and inter-symbol interference effectively. More importantly, they offer robust detection performance against the effective signature distortion caused by aliasing at the receiver.
