Download or read book The Performance Analysis of Space Time Spreading CDMA on Transmit and Receive Antenna Diversity Systems with Imperfect Channel Estimation written by Norihito Aoki and published by . This book was released on 2002 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Space Time Processing for CDMA Mobile Communications written by Pieter van Rooyen and published by Springer Science & Business Media. This book was released on 2005-12-21 with total page 320 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space-Time Processing for CDMA Mobile Communications is one of the first books to: bring together spatial/temporal channel models and analytic performance evaluation techniques; establish a link between smart antenna systems and advanced receiver design techniques; treat smart antennas specifically for UMTS-like communication systems, with applicable simulations and calculations; supply code with Matlab® GUI so readers can run or modify existing simulations or create new ones. The field of smart antenna technology or, more generally, space-time processing is rapidly becoming one of the most promising areas of mobile communications, especially regarding the development of the first practical third-generation mobile communication systems. The authors have addressed many of the most basic questions relating to the use of space-time processing in CDMA-based third-generation systems and have presented models for the integration of space-time processing, error correction coding, and multi-user detection techniques. Included is extensive background information on cellular systems, antenna array theory, smart antenna techniques, performance of basic space-time processors and advanced space-time processors. The book also includes an extensive simulation program written in Matlab®. The simulation code implements both the uplink and the downlink of a UMTS-like communication system. This provides multiple options for simulating system performance using a variety of channel models as well as receiver structures. Space-Time Processing for CDMA Mobile Communications will be an invaluable reference work for engineers and researchers, and a useful source for design engineers enabling them to understand the implications of adding space-time processing systems to CDMA-based communication systems.

Download or read book The Effects of Channel Estimation Errors on Wideband CDMA Systems with Path Frequency Time and Space Diversity written by Lucy Lok-Kwan Chong and published by . This book was released on 2001 with total page 222 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Space time Spreading and Transmit Diversity for DS CDMA Systems Over Fading Channels written by Mohamed Aljerjawi and published by . This book was released on 2006 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Space time Diversity for CDMA Systems Over Frequency selective Fading Channels written by Ayman M. Assra and published by . This book was released on 2010 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Supporting the expected high data rates required by wireless Internet and high-speed multimedia services is one of the basic requirements in broadband mobile wireless systems. However, the achievable capacity and data rate of wireless communication systems are limited by the time-varying nature of the channel. Efficient techniques for combating the time-varying effects of wireless channels can be achieved by utilizing different forms of diversity. In recent years, transmit diversity based on space-time coding (STC) has received more attention as an effective technique for combating fading. On the other hand, most existing space-time diversity techniques have been developed for flat-fading channels. Given the fact that wireless channels are generally frequency-selective, in this thesis, we aim to investigate the performance of space-time diversity schemes for wideband code-division multiple-access (WCDMA) systems over frequency-selective fading channels. The proposed receiver in this case is a rake-type receiver, which exploits the path diversity inherent to multipath propagation. Then, a decorrelator detector is used to mitigate the multiple access interference (MAI) and the known near-far problem. We derive the bit error rate (BER) expression over frequency-selective fading channels considering both the fast and slow fading cases. Finally, we show that our proposed receiver achieves the full system diversity through simulation and analytical results. Most of the work conducted in this area considers perfect knowledge of the channel at the receiver. Hence, channel identification brings significant challenges to multiple-input multiple-output (MIMO) CDMA systems. In light of this, we propose a channel estimation and data detection scheme based on the superimposed training-based approach. The proposed scheme enhances the performance by eliminating the MAI from both the channel and data estimates by employing two decorrelators; channel and data decorrelators. The performance of the proposed estimation technique is investigated over frequency-selective slow fading channels where we derived a closed-form expression for the BER as a function of the number of users, K, the number resolvable paths, L, and the number of receive antennas, V . Finally, our proposed scheme is shown to be more robust to channel estimation errors. Furthermore, both the analytical and simulation results indicate that the full system diversity is achieved. Considering that training estimation techniques suffer either from low spectral efficiency (i.e., conventional training approach) or from high pilot power consumption (i.e., superimposed training-based approach), in the last part of the thesis, we present an iterative joint detection and estimation (JDE) using the expectation-maximization (EM) algorithm for MIMO CDMA systems over frequency-selective fading channels. We also derive a closed-form expression for the optimized weight coefficients of the EM algorithm, which was shown to provide significant performance enhancement relative to the conventional equal-weight EM-based signal decomposition. Finally, our simulation results illustrate that the proposed receiver achieves near-optimum performance with modest complexity using very few training symbols.

Download or read book Multi Carrier and Spread Spectrum Systems written by Khaled Fazel and published by John Wiley & Sons. This book was released on 2008-09-15 with total page 384 pages. Available in PDF, EPUB and Kindle. Book excerpt: The technological progress in multi-carrier (MC) modulation led orthogonal frequency division multiplexing (OFDM) to become an important part of beyond 3G cellular mobile communication standards, including LTE and WiMAX. In addition, the flexibility offered by the spread spectrum (SS) and time division multiplexing (TDM) techniques motivated many researchers to investigate several MC combined multiple access schemes, such as MC-CDMA, OFDMA and MC-TDMA. These schemes benefit from the advantages of each sub-system and offer high flexibility, high spectral efficiency, simple detection strategies and narrow-band interference rejection capability. Multi-Carrier and Spread Spectrum Systems is one of the first books to describe and analyze the basic concepts of multi-carrier OFDM transmission and its combination with spread spectrum (MC-CDMA). The different architectures and detection strategies as well as baseband-related transceiver components are explained. This includes topics like FEC channel coding and decoding, modulation and demodulation (IFFT/FFT), digital I/Q-generation, time and frequency synchronisation, channel estimation, frequency domain equalization and RF aspects such as phase noise and non-linearity issues. Concrete examples of its applications for cellular mobile communication systems (B3G/4G) are given. Further derivatives of MC-SS (such as OFDMA, SS-MC-MA and DFT-spread OFDM) and their corresponding applications in the LTE, WiMAX, WLAN and DVB-RCT standards are detailed. Capacity and flexibility enhancements of multi-carrier OFDM systems by different MIMO diversity techniques such as space time/frequency coding (STC, SFC) and software defined radio concepts are also described. Written in a highly accessible manner this book provides a unique reference on the topics of multi-carrier and spread spectrum communications, assisting 4G engineers with their implementation. Fully updated new edition of successful text, including two new chapters on LTE and WiMAX Describes in detail new applications of OFDM in mobile communication standards Examines all multi-carrier spread spectrum schemes, with in-depth analysis, from theory to practice Introduces the essentials of important wireless standards based on multi-carrier/spread spectrum techniques.

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 Coded Transmit Diversity in CDMA Over Nakagami m Fading Channels written by Ariel Sacramento and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book The Effects of Spatial Diversity and Imperfect Channel Estimation on Wideband MC DS CDMA and MC CDMA written by and published by . This book was released on 2009 with total page 14 pages. Available in PDF, EPUB and Kindle. Book excerpt: In our previous work, we compared the theoretical bit error rates of multi-carrier direct sequence code division multiple access (MC-DS-CDMA) and multi-carrier code division multiple access (MC-CDMA). To ensure a fair comparison, we constrained both schemes to the same bandwidth, information rate, and energy-per-bit, and these constraints resulted in a possible trade-off between diversity gain and channel estimation errors between the two schemes. While only a single-input single-output (SISO) system was considered in our previous work, in this paper, we extend the comparison to a multiple-input multiple-output (MIMO) system which employs Alamouti spacetime block coding at each sub-carrier frequency to achieve spatial diversity. We consider only those cases where MC-CDMA has higher frequency diversity than MC-DS-CDMA. Since increases in diversity yield diminishing gains, we conclude that the addition of spatial diversity to this multi-carrier comparison benefits MCDS-CDMA more than MC-CDMA. To determine whether these gains for MC-DS-CDMA are enough to offset the difference in frequency diversity between the two schemes, we derive closed form expressions for the bit error probabilities of both schemes, and we compare the MIMO results against those of the SISO system for different information rates, number of users, and number of pilot symbols per channel estimate.

Download or read book Spread Spectrum and CDMA written by Valeri P. Ipatov and published by John Wiley & Sons. This book was released on 2005-05-06 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: Spread spectrum and CDMA are cutting-edge technologies widely used in operational radar, navigation and telecommunication systems and play a pivotal role in the development of the forthcoming generations of systems and networks. This comprehensive resource presents the spread spectrum concept as a product of the advancements in wireless IT, shows how and when the classical problems of signal transmission/processing stimulate the application of spread spectrum, and clarifies the advantages of spread spectrum philosophy. Detailed coverage is provided of the tools and instruments for designing spread spectrum and CDMA signals answering why a designer will prefer one solution over another. The approach adopted is wide-ranging, covering issues that apply to both data transmission and data collection systems such as telecommunications, radar, and navigation. Presents a theory-based analysis complemented by practical examples and real world case studies resulting in a self-sufficient treatment of the subject Contains detailed discussions of new trends in spread spectrum technology such as multi-user reception, multicarrier modulation, OFDM, MIMO and space-time coding Provides advice on designing discrete spread spectrum signals and signal sets for time-frequency measuring, synchronization and multi-user communications Features numerous Matlab-based problems and other exercises to encourage the reader to initiate independent investigations and simulations This valuable text provides timely guidance on the current status and future potential of spread spectrum and CDMA and is an invaluable resource for senior undergraduates and postgraduate students, lecturers and practising engineers and researchers involved in the deployment and development of spread spectrum and CDMA technology. Supported by a Companion website on which instructors and lecturers can find a solutions manual for the problems and Matlab programming, electronic versions of some of the figures and other useful resources such as a list of abbreviations.

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 228 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.

Download or read book Performance Evaluation of Transmit Diversity Techniques in the CDMA 2000 Standard written by Murali Srinivasan Vajapeyam and published by . This book was released on 2004 with total page 123 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis evaluates the performance of two forward-link transmit diversity techniques in the CDMA2000 standard: Space-Time Spreading (STS) and Phase-Sweep Transmit Diversity (PSTD). For each technique, the evaluation consists of conducting 9.6 kbps Markov calls in the field and measuring the mean forward-link fundamental-channel (F-FCH) transmit power required to achieve a 1% frame error-rate (FER) at the mobile receiver. The required transmit power is used to compute an estimate of cell capacity as measured by the number of supported users, assuming a fixed total transmit power at the base station. It is observed that enabling STS increases capacity by up to 80% if all mobiles support STS, but capacity is reduced by up to 20% when fewer than 35% of the mobiles support the technique. The capacity loss results from interference of the diversity-antenna signal on mobiles that do not support STS; such interference causes an F-FCH transmit power increase of up to 1.5 dB in multipath Rayleigh-faded channels, as observed in lab experiments. PSTD, which does not require mobile-specific support, was found to improve cell capacity by 12% according to the field experiments.

Download or read book Electrical Electronics Abstracts written by and published by . This book was released on 1997 with total page 2304 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Channel Estimation and Linear Precoding for CDMA with Space time Transmit Diversity microform written by Hanli Wang and published by Library and Archives Canada = Bibliothèque et Archives Canada. This book was released on 2004 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: Space-time block coding (STBC) is a well-known way to create transmit diversity in wireless communications. Space-time transmit diversity (STTD) is an extension of STBC to code division multiple access (CDMA) systems. To date, most discussions of STTD have assumed flat fading or ignored multi-access and inter-symbol interference (MAI and ISI) induced by frequency selective fading. This thesis demonstrates that MAI and ISI can cause an unacceptable breakdown in STTD performance with conventional interference-limited channel estimation methods. Therefore, two improved channel estimation methods are proposed for STTD in frequency selective fading. This thesis also studies the performance degradation of STTD due to spatially correlated frequency selective fading and develops a linear precoding scheme for STTD based on channel correlation knowledge. The simulation results show that the performance of STTD is significantly improved using the proposed channel estimation methods and the linear precoding scheme.

Download or read book Performance Analysis of Adaptive Chaos based DS CDMA System with Imperfect Channel Estimation written by Meher Krishna Patel and published by . This book was released on 2017 with total page 116 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis presents the analysis of chaos-based direct sequence code division multiple access (DS-CDMA) systems under imperfect channel estimation environments. Chaos-based CDMA systems are studied extensively in the last few decades, but their performances under imperfect channel estimation conditions are never studied. The main motivation of the thesis is to fill this research gap under various possible conditions. The thesis focuses on three main objectives. The first objective is to determine the effect of spreading sequences in channel estimation processes. Here performances of channel estimators in the presence and absence of chaotic spreading sequences are investigated. The second objective is to study the performances of imperfect channel estimations in chaos based CDMA systems under various fading conditions. This part mainly focuses on the various factors which deteriorate the performance of the systems. The third objective focuses on the various techniques which can improve the performances of the systems. In this part various available techniques for CDMA systems are studied under imperfect channel estimation environments. It is concluded that performances of all the available chaos based CDMA systems significantly depend on performances of channel estimators. Analytical simulation results in the thesis show that performance degradation in available systems due to various fading channels can be significantly improved by using channel estimators.

Download or read book Performance Analysis of Multi antenna OFDM Systems with Phase Noise and Imperfect Channel Estimation written by Mohamed Jalloh and published by . This book was released on 2009 with total page 197 pages. Available in PDF, EPUB and Kindle. Book excerpt: The age of wireless technologies and the associated convenience that portable wireless products and services provide, continues to drive the need for more advanced products and broadband wireless services that demand carefully selected spectrally efficient modulation schemes to support the desired higher data rates. The development of multicarrier systems has paved the way to meeting the system requirements and fulfilling these needs. Orthogonal Frequency Division Multiplexing (OFDM) is a multicarrier modulation technique that has provided effective means for achieving high data rates and spectral efficiency requirements in wireless communication systems, while making use of relatively simple receiver designs. In wireless communications, one of the major implementation challenges is system sensitivity to synchronization issues, which is even more pronounced in multicarrier systems such as OFDM. The use of OFDM with a high number of subcarriers, to achieve the high data rates it provides, makes it more susceptible to these non-idealities such as phase noise. Another critically limiting factor of system performance is the introduction of channel estimation errors as a consequence of imperfect channel estimation at the receiver. Accurate channel estimates are very essential in ensuring correct detection of the transmitted signal at the receiver. A thorough understanding of system operation therefore requires a detailed analysis of the effects of all the impairments. This dissertation addresses these system impairments by investigating the effects analytically on OFDM systems, deriving bit error rate (BER) expressions for systems that employ a single antenna at both the transmitter and receiver. The investigation is extended to also include OFDM systems that employ multi-antenna configurations at the receiver followed by a similar multi-antenna configuration at the transmitter. The impact of these negative effects is further investigated when applied to a practical system, comparing the analytical results with simulations that makes use of system parameters of the IEEE 802.16 standards.

Download or read book Wireless Communications written by Savo G. Glisic and published by Springer Science & Business Media. This book was released on 2013-03-14 with total page 535 pages. Available in PDF, EPUB and Kindle. Book excerpt: In Time Division Multiple Access (TDMA), within a given time frame a particular user is allowed to transmit within a given time slot. This technique is used in most of the second-generation digital mobile communication systems. In Europe the system is known as GSM, in USA as DAMPS and in Japan as MPT. In Code Division Multiple Access (CDMA) every user is using a distinct code so that it can occupy the same frequency bandwidth at the same time with other users and still can be separated on the basis of low correlation between the codes. These systems like IS-95 in the USA are also developed and standardized within the second generation of the mobile communication systems. CDMA systems within a cellular network can provide higher capacity and for this reason they become more and more attractive. At this moment it seems that both TDMA and CDMA remain viable candidates for application in future systems. Wireless Communications: TDMA versus CDMA provides enough information for correct understanding of the arguments in favour of one or other multiple access technique. The final decision about which of the two techniques should be employed will depend not only on technical arguments but also on the amount of new investments needed and compatibility with previous systems and their infrastructures. Wireless Communications: TDMA versus CDMA comprises a collection of specially written contributions from the most prominent specialists in wireless communications in the world today and presents the major, up to date, issues in this field. The material is grouped into four chapters: Communication theory, covering coding and modulation, Wireless communications, Antenna & Propagation and Advanced Systems & Technology. The book describes clearly the issues and presents the information in such a way that informed decisions about third generation wireless systems can be taken. It is essential reading for all researchers, engineers and managers working in the field of Wireless Communications.