Multiuser Detection for Mobile CDMA Systems PDF Download

Author: M. Mozaffaripour
Publisher:
ISBN:
Category :
Languages : en
Pages :

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Author: Paulo Silva
Publisher: CRC Press
ISBN: 1000794156
Category : Science
Languages : en
Pages : 264

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Book Description
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: 9781580538015
Category : Technology & Engineering
Languages : en
Pages : 256

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Book Description
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: Ulrich Jetzek
Publisher:
ISBN: 9783183542109
Category :
Languages : en
Pages : 116

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Author: CHRISTIAN SCHLEGEL
Publisher: Springer Science & Business Media
ISBN: 140204075X
Category : Technology & Engineering
Languages : en
Pages : 282

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Book Description
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: Abdallah Kayed Farraj
Publisher:
ISBN:
Category :
Languages : en
Pages : 109

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Author: Zhiwei Mao
Publisher:
ISBN:
Category :
Languages : en
Pages :

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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: Sergio Verdú
Publisher: Cambridge University Press
ISBN: 9780521593731
Category : Computers
Languages : en
Pages : 478

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

Author: Yevgeny Visotsky
Publisher:
ISBN:
Category :
Languages : en
Pages : 68

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Author: Homoud M. I. Alkussayer
Publisher:
ISBN:
Category :
Languages : en
Pages : 180

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Book Description
In this thesis a group of simplified multiuser receivers for a CDMA system are presented and evaluated. The problem of multiuser detection in a synchronous channel is considered where a class of new simplified sub-optimum bear multiuser detectors are suggested, for both the decorrelating and the MMSE detectors. It is shown that by using Gold code as the spreading sequence the complexity of the two new multiuser detectors is independent of the number of users. For an asynchronous CDMA system a one-shot linear decorrelating detector is investigated. A novel improved one-shot detector which outperforms Verdu's one-shot detector with much reduced complexity is proposed. A second new detector using non-orthogonal matching which reduces the complexity even further, with small reduction in performance, is also suggested. A third is the matched filter slicing detector which is a more simplified detector for a special system. For the same channel, a novel CDMA system using dual-signalling with multiuser detection is presented. Using a replicated spreading sequence at the transmitters and halved correlation period plus linear combining at the central station, a one-shot detection is achieved. Two decorrelating algorithms, the direct method and the recursive method, are presented. Theoretical and simulation results showed that this scheme significantly outperforms the conventional detector and its performance approaches that of the single user. Finally, the multiuser detection in a frequency non-selective Rayleigh fading channel is studied. Two novel detectors are proposed.The first uses dual-signalling without interleaving, which results in a greatly simplified near-far resistant detector. The second uses dual-signalling with interleaving which results in a slightly more complex detector. The performance of both detectors is however superior to the conventional detector, and they can outperform the original LDD detector which is far too complex.