Download or read book THE CODING SPREADING TRADEOFF PROBLEM IN FINITE SIZED SYNCHRONOUS DS CDMA SYSTEMS written by and published by . This book was released on 2005 with total page 268 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation provides a comprehensive analysis of the coding-spreading tradeoff problem in finite-sized synchronous DS-CDMA systems. In contrast to the large system which has a large number of users, the finite-sized system refers to a system with a small number of users. Much work has been performed in the past on the analysis of the spectral efficiency of synchronous DS-CDMA systems and the associated coding-spreading tradeoff problem. However, most of the analysis is based on the large-system assumptions. In this dissertation, we focused on finite-sized systems with the help of numerical methods and Monte-Carlo simulations. Binary-input achievable information rates for finite-sized synchronous DS-CDMA systems with different detection/decoding schemes on AWGN channel are numerically calculated for various coding/spreading apportionments. We use these results to determine the existence and value of an optimal code rate for a number of different multiuser receivers, where optimality is in the sense of minimizing the SNR required for reliable multiuser communication. Our results are consistent with the well-known fact that all coding (no spreading) is optimal for the maximum a posteriori receiver. Simulations of the LDPC-coded synchronous DS-CDMA systems with iterative multiuser detection/decoding and MMSE multiuser detection/single-user decoding are also presented to show that the binary-input capacities can be closely approached with practical schemes. The coding-spreading tradeoff is examined using these LDPC code simulation results, where agreement with the information-theoretic results is demonstrated. We extend our work to the DS-CDMA systems on two idealized Rayleigh flat-fading channels: the chip-level flat-fading (CLFF) and the (code) symbol-level flat-fading (SLFF). These models represent ideal fast fading and slow fading channels, respectively. Both information-theoretic results and LDPC code simulation results are presented to show the effects of channel fading on system performance and the coding-spreading tradeoff. It is shown that fast fading can be beneficial to system performance under the condition of perfect channel state information at receiver, but slow fading is very harmful. Slow fading also increases the importance of coding greatly, compared to the AWGN and fast fading. Finally, we present some comparisons with large-system results on AWGN and CLFF channels, which show both consistencies and discrepancies.

Download or read book Coding Spreading Tradeoff in CDMA Systems written by Eduardo J. Bolas and published by . This book was released on 2002-09-01 with total page 111 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis we investigate the usage of low rate codes primarily to provide the total bandwidth expansion required for a CDMA system. Comparing different combinations of coding and spreading with a traditional DS-CDMA, as defined in the IS-95 standard, allows the criteria to be defined for the best coding-spreading tradeoff in CDMA systems. The analysis of the coding-spreading tradeoff is divided into two parts. The first part is dedicated to the study of the deterministic components of the problem. This includes the different factors with non-random behavior that the system's designer can determine. The processing gain, the code characteristics and the number of users are well- defined variables that can determine the overall performance and can consequently affect the tradeoff. The second part of the study is dedicated to analyzing different combinations of coding and spreading with no ideal channel estimation and interference reduction techniques. Small-scale fading channel conditions are emulated through Nakagami-m distribution. Large-scale path loss was incorporated through the extended Hata model while Lognormal shadowing considered the fluctuations on the received power at points with the same distance to the transmitter. We assessed the performance of different combinations of coding and spreading considering in two cases: a worst-case scenario in which the mobile user was located at the corner of a hexagon cell in a seven-cell cluster and a more realistic scenario in which the user could be physically located anywhere in the cell, following a uniform probability distribution function. Furthermore, we investigated the improvement in performance generated by interference reduction techniques, such as sectoring and power control.

Download or read book Cross layer Design of Wideband CDMA Systems and Cooperative Diversity for Wireless Ad Hoc Networks written by Ramesh Annavajjala and published by . This book was released on 2006 with total page 145 pages. Available in PDF, EPUB and Kindle. Book excerpt: Some of the challenges in the design of next generation wireless systems are providing high data rate multimedia services, increasing user capacity, improving reliability and range, terminal mobility, robustness to interference, limited spectrum availability, and transmission power constraints. The approaches that we take in this dissertation to address some of the aforementioned issues are cross-layer design and user cooperation. In the first part of the dissertation, on a wideband CDMA channel with a finite transmission bandwidth constraint, we consider the problem of optimal bandwidth allocation for source coding, channel coding and spread-spectrum modulation. For analytical tractability, we assume a memoryless Gaussian source with an optimum quantizer, a convolutional encoder with a soft-decision decoder, and a spread spectrum modulator with random spreading codes and a RAKE receiver. In the presence of both multiple access interference (MAI) and narrowband interference (NBI), for frequency-selective Nakagami fading channels, we derive upper and lower bounds on the end-to-end average source distortion. Since an exact expression for the average distortion is difficult to derive, we seek to obtain the three-tuple (i.e., source coding rate, channel coding rate, and spreading factor) that optimizes the upper and lower bounds on the average distortion. Under various channel conditions and interference levels, we numerically computed the optimum three-tuple, and verify the accuracy with system-level simulations. For small values of spreading factor, we show that the system performance is hurt by the self-interference of the user-of-interest, thus cautioning against aggressive channel coding. Since a multi-carrier DS-CDMA (or, simply MC-CDMA) system is more robust to NBI, we propose to employ an MC-CDMA system to improve the distortion performance on channels with severe NBI. For a fixed channel code rate, we then quantify the tradeoff between source coding and spreading for an MC-CDMA system. In the second part of the dissertation, we consider a parallel relay channel wherein the relay nodes help the source transmissions to provide improved reliability at the destination. With multiple relay nodes, we design and analyze robust noncoherent amplify-and forward receivers for use on rapidly varying Rayleigh fading channels with unknown instantaneous channel knowledge. Next, with a sum power constraint, we consider the problem of optimal transmit power allocation when only statistical knowledge, in terms of the average fading power, of the channel is available at the transmitting nodes. We quantify the improvements in both outage probability performance and asymptotic cooperation gain of various relaying protocols with optimal power allocation.

Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2240 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book 2000 IEEE International Conference on Acoustics Speech and Signal Processing written by and published by . This book was released on 2000 with total page 858 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Fundamentals of Wireless Communication written by David Tse and published by Cambridge University Press. This book was released on 2005-05-26 with total page 598 pages. Available in PDF, EPUB and Kindle. Book excerpt: This textbook takes a unified view of the fundamentals of wireless communication and explains cutting-edge concepts in a simple and intuitive way. An abundant supply of exercises make it ideal for graduate courses in electrical and computer engineering and it will also be of great interest to practising engineers.

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.

Download or read book Synchronization in Digital Communication Systems written by Fuyun Ling and published by Cambridge University Press. This book was released on 2017-06-22 with total page 399 pages. Available in PDF, EPUB and Kindle. Book excerpt: This practical guide helps readers to learn how to develop and implement synchronization functions in digital communication systems.

Download or read book OFDM and MC CDMA for Broadband Multi User Communications WLANs and Broadcasting written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2005-01-28 with total page 1014 pages. Available in PDF, EPUB and Kindle. Book excerpt: Orthogonal frequency-division multiplexing (OFDM) is a method of digital modulation in which a signal is split into several narrowband channels at different frequencies. CDMA is a form of multiplexing, which allows numerous signals to occupy a single transmission channel, optimising the use of available bandwidth. Multiplexing is sending multiple signals or streams of information on a carrier at the same time in the form of a single, complex signal and then recovering the separate signals at the receiving end. Multi-Carrier (MC) CDMA is a combined technique of Direct Sequence (DS) CDMA (Code Division Multiple Access) and OFDM techniques. It applies spreading sequences in the frequency domain. Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. This technical in-depth book is unique in its detailed exposure of OFDM, MIMO-OFDM and MC-CDMA. 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 three main parts: Part I provides a detailed exposure of OFDM designed for employment in various applications Part II is another design alternative applicable in the context of OFDM systems where the channel quality fluctuations observed are averaged out with the aid of frequency-domain spreading codes, which leads to the concept of MC-CDMA Part III discusses how to employ multiple antennas at the base station for the sake of supporting multiple users in the uplink Portrays the entire body of knowledge currently available on OFDM Provides the first complete treatment of OFDM, MIMO(Multiple Input Multiple Output)-OFDM and MC-CDMA Considers the benefits of channel coding and space time coding in the context of various application examples and features numerous complete system design examples Converts the lessons of Shannon’s information theory into design principles applicable to practical wireless systems Combines the benefits of a textbook with a research monograph where the depth of discussions progressively increase throughout the book This all-encompassing self-contained treatment will appeal to researchers, postgraduate students and academics, practising research and development engineers working for wireless communications and computer networking companies and senior undergraduate students and technical managers.

Download or read book Digital Communications Fundamentals Applications 2 E written by Sklar and published by Pearson Education India. This book was released on 2009-09 with total page 1168 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book OFDM and MC CDMA written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2007-01-11 with total page 430 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless communications has witnessed a tremendous growth during the past decade and further spectacular enabling technology advances are expected in an effort to render ubiquitous wireless connectivity a reality. Currently, a technical in-depth book on this subject is unavailable, which has a similar detailed exposure of OFDM, MIMO-OFDM and MC-CDMA. 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 three main parts: Part I provides a detailed exposure of OFDM designed for employment in various applications Part II is another design alternative applicable in the context of OFDM systems where the channel quality fluctuations observed are averaged out with the aid of frequency-domain spreading codes, which leads to the concept of MC-CDMA Part III discusses how to employ multiple antennas at the base station for the sake of supporting multiple users in the uplink By providing an all-encompassing self-contained treatment this volume will appeal to a wide readership, as it is both an easy-reading textbook and a high-level research monograph.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2006 with total page 860 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multiuser Detection written by Sergio Verdú and published by Cambridge University Press. This book was released on 1998-08-13 with total page 478 pages. Available in PDF, EPUB and Kindle. Book excerpt: Originally published in 1998, Multiuser Detection provides a comprehensive treatment of the subject of multiuser digital communications.

Download or read book Principles of Mobile Communication written by Gordon L. Stüber and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 670 pages. Available in PDF, EPUB and Kindle. Book excerpt: Principles of Mobile Communication provides an authoritative treatment of the fundamentals of mobile communications, one of the fastest growing areas of the modern telecommunications industry. The book stresses the fundamentals of mobile communications engineering that are important for the design of any mobile system. Less emphasis is placed on the description of existing and proposed wireless standards. This focus on fundamental issues should be of benefit not only to students taking formal instruction but also to practising engineers who are likely to already have a detailed familiarity with the standards and are seeking to deepen their knowledge of this important field. The book stresses mathematical modeling and analysis, rather than providing a qualitative overview. It has been specifically developed as a textbook for graduate level instruction and a reference book for practising engineers and those seeking to pursue research in the area. The book contains sufficient background material for the novice, yet enough advanced material for a sequence of graduate level courses. Principles of Mobile Communication treats a variety of contemporary issues, many of which have been treated before only in the journals. Some material in the book has never appeared before in the literature. The book provides an up-to-date treatment of the subject area at a level of detail that is not available in other books. Also, the book is unique in that the whole range of topics covered is not presently available in any other book. Throughout the book, detailed derivations are provided and extensive references to the literature are made. This is of value to the reader wishing to gain detailed knowledge of a particular topic.

Download or read book Proceedings written by and published by . This book was released on 1995 with total page 662 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Multi Carrier Spread Spectrum Related Topics written by Khaled Fazel and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 368 pages. Available in PDF, EPUB and Kindle. Book excerpt: Khaled Fazel Stefan Kaiser Digital Microwave Systems German Aerospace Center (DLR) Bosch Telecom GmbH Institute for Communications Technology D-71522 Backnang, Germany D-82234 Wessling, Germany In this last decade of this millennium the technique of multi-carrier transmission for wireless broadband multimedia applications has been receiving wide interests. Its first great success was in 1990 as it was selected in the European Digital Audio Broadcasting (DAB) standard. Its further prominent successes were in 1995 and 1998 as it was selected as modulation scheme in the European Digital Video Broadcasting (DVB-T) and in three broadband wireless indoor standards, namely ETSI-Hiperlan-II, American IEEE-802. 11 and Japanese MMAC, respectively. The benefits and success of multi-carrier (MC) modulation in one side and the flexibility offered by spread spectrum (SS) technique in other hand motivated many researchers to investigate the combination of both techniques, known as multi-carrier spread-spectrum (MC-SS). This combination benefits from the main 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 SS (DS-SS) but instead of transmitting the chips over a single sequence carrier, several sub-carriers could be employed. As depicted in Figure 1, after spreading with assigned user specific code of processing gain G the frequency mapping and multi-carrier modulation is applied. In the receiver side after multi-carrier demodulation and frequency de-mapping, the corresponding detection algorithm will be performed.

Download or read book Broadband Wireless Communications written by Marco Luise and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 437 pages. Available in PDF, EPUB and Kindle. Book excerpt: Broadband Wireless Access is a highly challenging and fast changing area of multimedia radio communications. These papers on the subject are the proceedings of the 9th Tyrrhenian Workshop, held in Lerici, Italy, September 1997. They provide a prospect on the state of the art and future development, with a sufficiently wide focus to cover technological, architectural and regulatory issues. Emphasis is given to those advances of digital signal processing techniques, microwave mono lithic integrated circuits and smart antennae that will allow the design of low cost user terminals with advanced capabilities. Specific attention is also devoted to the protocols these new terminals will use to access the radio medium, and to the kind of services that will eventually be provided to the end-user in the future. With contributions from worldwide experts, the material presented here is a timely and high-level overview of the field, and as well as being informative is a useful tool for promoting further investigation into the area of multimedia radio communications.