Download or read book Transmitter Based Multiple Access Interference Rejection and Diversity Techniques for Code Division Multiple Access Systems written by Jia Liu and published by . This book was released on 2005 with total page 121 pages. Available in PDF, EPUB and Kindle. Book excerpt: Keywords: transmit diversity, multiuser detection, CDMA, multiple access interference, multiuser precoding.
Download or read book A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct Sequence Code Division Multiple Access Communications written by Yuejin Huang and published by . This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct-sequence Code Division Multiple Access Communications" by 黃耀進, Yuejin, Huang, was obtained from The University of Hong Kong (Pokfulam, Hong Kong) and is being sold pursuant to Creative Commons: Attribution 3.0 Hong Kong License. The content of this dissertation has not been altered in any way. We have altered the formatting in order to facilitate the ease of printing and reading of the dissertation. All rights not granted by the above license are retained by the author. DOI: 10.5353/th_b3123707 Subjects: Wireless communication systems Code division multiple access Spread spectrum communications
Download or read book Transmitter Diversity and Multiuser Precoding for Rayleigh Fading Code Division Multiple Access Channels written by and published by . This book was released on 2003 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Transmitter diversity in the downlink for Code Division Multiple Access (CDMA) systems provides a means to achieve similar performance gains as for the mobile station (MS) receiver diversity without the complexity of a MS receiver antenna array. Transmitter based methods enable to shift signal processing to the transmitter where power and computational complexity are more abundant, thus simplifying receiver units. We examine feasibility of several transmitter diversity techniques for the Wideband CDMA (W-CDMA) systems. We also investigate an optimal method to combine transmitter diversity and precoding that achieves the gain of maximum ratio combining of all space and frequency diversity branches. Under severe channel conditions (i.e. multipath), the multiple access interference (MAI) becomes the major source of performance degradation for direct sequence CDMA (DS/CDMA) systems. This is because of the loss of orthogonality between the spreading codes used by each user due to the multipath channel effects. To overcome this problem, many receiver based multiuser detection (MUD) techniques have been proposed. These techniques demand high computational complexity, power and knowledge of spreading codes of all users. As a result, in the downlink of a CDMA system it is not feasible to employ such methods at the MS. Alternatively, transmitter based techniques were proposed to shift computational complexity and power consumption to the BS, where they can be afforded. It was shown that these methods are very effective in removing the MAI. Although these methods are powerful, they are high in complexity and require the accurate knowledge of the channel. since MAI cancellation filters need to be updated continuously as fading coefficients vary. We propose a less complex method with similar performance improvements. In the proposed method, the functions of multipath combining and MAI cancellation are separated. Thus the MAI cancellation matrix does not depend on rapidly time-va.
Download or read book Interference Rejection and Management written by and published by . This book was released on 2009 with total page 35 pages. Available in PDF, EPUB and Kindle. Book excerpt: We consider interference suppression in several wireless communication systems. The first topic treated is self-interference encountered among cooperating systems, for example, the self-interference that is encountered in cognitive radio systems and ultra-wideband (UWB) communication systems. Both single-carrier, direct sequence signals and multicarrier signals are considered, and the effects of the interference on the performance of a direct sequence UWB system that employs channel state estimation in the presence of the interference is evaluated. The second topic that is treated is the mitigation of narrowband interference in block-modulated multicarrier systems. Two schemes, multicarrier code-division multiple access (MC-CDMA) and orthogonal frequency division multiplexing (OFDM), are investigated. The inherent frequency diversity of MC-CDMA through the use of spreading codes allows for robustness against interference. Conversely, OFDM must employ a signal processing technique to suppress the interference due to its lack of frequency diversity. The performance of OFDM is improved with the addition of forward error correction (FEC) coding in the frequency domain, thereby providing the system with frequency diversity. The third topic is the suppression of interference in multiple input, multiple output (MIMO) wireless communication systems that employ multiple-transmit and multiple-receive antennas to increase the data rate and achieve signal diversity in fading multipath channels. Interference in MIMO wireless communication systems usually consists of intersymbol interference (ISI) due to channel multipath dispersion and cross-talk, or interchannel interference, due to the simultaneous transmissions from the multiple-transmit antennas. The focus of the section is on point-to-multipoint (broadcast) MIMO systems in which the channel characteristics are assumed to be known at the transmitter, so that interference mitigation can be performed at the transmitter.
Download or read book Multiple Access Channels written by Ezio Biglieri and published by IOS Press. This book was released on 2007 with total page 360 pages. Available in PDF, EPUB and Kindle. Book excerpt: Surveys general results on multiple-access channels, and gives an overview of the problems of CDMA solutions. This work includes chapters devoted to the information-theoretical aspects of multiple-access communication. It discusses multiple-access techniques and covers coding techniques.
Download or read book Transmitter Based Interference Rejection for Wireless CDMA Systems written by Anupama Dharap and published by . This book was released on 1998 with total page 154 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Multiple Access Interference Rejection Technique Using Weighted Despreading Functions for Direct sequence Code Division Multiple Access Communications written by Yuejin Huang and published by . This book was released on 1998 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Interleave Division Multiple Access for Wireless Communication written by Manoj Kumar Shukla and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: [Enter Abstract Body]This paper outlines a multiple access technique which exploits the interleaving as only means of user separation instead of by different signatures as in a conventional code division multiple-access (CDMA) scheme. It examines a very simple iterative chip-by-chip multi-user detection strategy for spread spectrum communication systems. The given scheme can achieve near single user performance in situations with very large numbers of users while maintaining very low receiver complexity. This technique shows that high performance can be maintained in multi-path environments. IDMA inherits many advantages from CDMA, such as diversity against fading and mitigation of the worst-case user interference problem. A low-cost iterative chip-by-chip multi-user detection algorithm is also described with complexity independent of the user number and increasing linearly with the path number.
Download or read book Reducing Multiple Access Interference in Broadband Multi user Wireless Networks written by Ali Nayef Alqatawneh and published by . This book was released on 2015 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation is devoted to developing multiple access interference (MAI) reduction techniques for multi-carrier multi-user wireless communication networks. In multi-carrier code division multiple access (MC-CDMA) systems, a full multipath diversity can be achieved by transmitting one symbol over multiple orthogonal subcarriers by means of spreading codes. However, in frequency selective fading channels, orthogonality among users can be destroyed leading to MAI. MAI represents the main obstacle to support large number of users in multi-user wireless systems. Consequently, MAI reduction becomes a main challenge when designing multi-carrier multi-user wireless networks. In this dissertation, first, we study MC-CDMA systems with different existing MAI reduction techniques. The performance of the studied systems can be further improved by using a fractionally spaced receivers instead of using symbol spaced receivers. A fractionally spaced receiver is obtained by oversampling received signals in a time domain. Second, a novel circular-shift division multiple access (CSDMA) scheme for multi-carrier multi-user wireless systems is developed. In CSDMA, each symbol is first spread onto multiple orthogonal subcarriers in the frequency domain through repetition codes. The obtained frequency-domain signals are then converted to a time-domain representation. The time-domain signals of different users are then circularly shifted by different numbers of locations. The time-domain circular shifting enables the receiver to extract signals from different users with zero or a small amount of MAI. Our results show that the CSDMA scheme can achieve a full multipath diversity with a performance outperforms that of orthogonal frequency division multiple access (OFDMA). Moreover, multipath diversity of CSDMA can be further improved by employing the time-domain oversampling. Performance fluctuations due to a timing offset between transmitter and receiver clocks in MC-CDMA and CSDMA systems can be removed by employing the time-domain oversampling. Third, we study the theoretical error performance of high mobility single-user wireless communication system with doubly selective (time-varying and frequency-selective) fading channel under impacts of imperfect channel state information (CSI). Throughout this dissertation, intensive computer simulations are performed under various system configurations to investigate the obtained theoretical results, excellent agreements between simulation and theoretical results were observed in this dissertation.
Download or read book Diversity Techniques in Direct Sequence Code Division Multiple Access Communication Systems written by Okechukwu C. Ugweje and published by . This book was released on 1997 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Advanced Communication and Networking written by Tai-hoon Kim and published by Springer Science & Business Media. This book was released on 2011-08-05 with total page 480 pages. Available in PDF, EPUB and Kindle. Book excerpt: This volume constitutes the refereed proceedings of the 3rd International Conference on Advanced Communication and Networking, ACN 2011, held in Brno, Czech Republik, in June 2011. The 57 revised full papers presented in this volume were carefully reviewed and selected from numerous submissions. The papers focus on the various aspects of progress in Advanced Communication and Networking with computational sciences, mathematics and information technology and address all current issues of communication basic and infrastructure, networks basic and management, multimedia application, image, video, signal and information processing.
Download or read book Advances in Multiuser Detection written by Michael L. Honig and published by John Wiley & Sons. This book was released on 2009-08-31 with total page 517 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.
Download or read book The Evolution of Untethered Communications written by National Research Council and published by National Academies Press. This book was released on 1998-01-01 with total page 208 pages. Available in PDF, EPUB and Kindle. Book excerpt: In response to a request from the Defense Advanced Research Projects Agency, the committee studied a range of issues to help identify what strategies the Department of Defense might follow to meet its need for flexible, rapidly deployable communications systems. Taking into account the military's particular requirements for security, interoperability, and other capabilities as well as the extent to which commercial technology development can be expected to support these and related needs, the book recommends systems and component research as well as organizational changes to help the DOD field state-of-the-art, cost-effective untethered communications systems. In addition to advising DARPA on where its investment in information technology for mobile wireless communications systems can have the greatest impact, the book explores the evolution of wireless technology, the often fruitful synergy between commercial and military research and development efforts, and the technical challenges still to be overcome in making the dream of "anytime, anywhere" communications a reality.
Download or read book Orthogonal Frequency Division Multiple Access Fundamentals and Applications written by Tao Jiang and published by CRC Press. This book was released on 2010-04-21 with total page 640 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supported by the expert-level advice of pioneering researchers, Orthogonal Frequency Division Multiple Access Fundamentals and Applications provides a comprehensive and accessible introduction to the foundations and applications of one of the most promising access technologies for current and future wireless networks. It includes authoritative cove
Download or read book Smart Spaces and Next Generation Wired Wireless Networking written by Sergey Balandin and published by Springer. This book was released on 2011-08-05 with total page 650 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book constitutes the refereed proceedings of the 11th International Conference on Next Generation Teletraffic and Wired/Wireless Advanced Networking, NEW2AN 2011 and the 4th Conference on Smart Spaces, ruSMART 2011 jointly held in St. Petersburg, Russia, in August 2011. The 56 revised full papers presented were carefully reviewed and selected from numerous submissions. The ruSMART papers are organized in topical sections on role of context in smart spaces, smart spaces platforms and smart-M3, methods for studying smart spaces, and smart spaces solutions. The NEW2AN papers are organized in topical sections on wireless PHY and power control, ad hoc networks, WSN, special topics, simulation + fundamental analysis I, traffic modeling and measurement, simulation + fundamental analysis II, network performance and QoS, cooperative, P2P, overlay networks and content, applications and services, API and software, and video.
Download or read book Diversity and Interference Aspects in the Downlink of Code Division Multiple Access Systems written by Anders Persson and published by . This book was released on 2004 with total page 25 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Multi Carrier and Spread Spectrum Systems written by K. Fazel and published by John Wiley & Sons. This book was released on 2004-02-06 with total page 298 pages. Available in PDF, EPUB and Kindle. Book excerpt: Frequency spectrum is a limited and valuable resource for wireless communications. A good example can be observed among network operators in Europe for the prices to pay for UMTS-frequency bands. Therefore, the first goal when designing future wireless communication systems (e.g. 4G - fourth generation) has to be the increase in spectral efficiency. The development in digital communications in the past years has enabled efficient modulation and coding techniques for robust and spectral efficient data, speech, audio and video transmission. These are the multi-carrier modulation (e.g. OFDM) and the spread spectrum technique (e.g. DS-CDMA), where OFDM was chosen for broadcast applications (DVB, DAB) as well as for broadband wireless indoor standards (ETSI HIPERLAN-II, IEEE-802.11) and the DS-CDMA was selected in mobile communications (IS-95, third generation mobile radio systems world wide, UMTS/IMT 2000). Since 1993 various combinations of multi-carrier (MC) modulation and the spread spectrum (SS) technique have been introduced and the field of MC-SS communications has become an independent and important research topic with increasing activities. New application fields have been proposed such as high rate cellular mobile, high rate wireless indoor and LMDS. It has been shown that MC-SS offers the high spectral efficiency, robustness and flexibility that is required for the next generation systems. Meanwhile, different alternative hybrid schemes such as OFDM/OFDMA, MC-TDMA, etc. have been deeply analysed and adopted in different international standards (ETSI-BRAN, IEEE-802 & MMAC). Multi-Carrier & Spread-Spectrum: Analysis of Hybrid Air Interfaces draws together all of the above mentioned hybrid schemes therefore providing a greatly needed resource for system engineers, telecommunication designers and researchers in order to enable them to develop, build and deploy several schemes based on MC-transmission for the next generation systems (which will be an integration of broadband multimedia services covering both 4G mobile and fixed wireless systems). * Offers a complete treatment of multi-carrier, spread-spectrum (SS) and time division multiplexing (TDM) techniques * Provides an in-depth insight into hybrid multiple access techniques based on multi-carrier (MC) transmission * Presents numerous hybrid multiple access and air interface architectures including OFDM/CDMA, MC-CDMA, MC-DS-CDMA and MT-CDMA * Covers new techniques such as space-time coding and software radio Telecommunications engineers, hardware & software system designers and researchers as well as students, lecturers and technicians will all find this an invaluable addition to their bookshelf.
