Download or read book Performance Analysis of Linear Multistage Interference Cancellation in Long code CDMA Systems written by Chien-Hwa Hwang and published by . This book was released on 2003 with total page 300 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Analysis of Parallel Interference Cancellation for CDMA Systems written by Yidai Li and published by . This book was released on 2002 with total page 160 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance Analysis of Integrated Interference Cancellation and Decoding for CDMA Systems written by and published by . This book was released on with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: HKUST Call Number: Thesis ELEC 2000 Shurk.

Download or read book Multistage Linear Multiuser Receivers written by Mohsen Ghotbi and published by . This book was released on 2005 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: This thesis introduces an analytical method for large-system design and analysis of multistage linear multiuser (MLMU) receivers for direct-sequence (DS- ) code division multiple access (CDMA) systems. The figure of merit to evaluate performance is the signal to interference plus noise ratio (SINR) that is calculated for a case where the number of active users and the processing gain tend towards infinity, while their ratio remains finite. The large-system performance will be a function of the number of the interference cancellation stages, the moments of the eigenvalues of the covariance matrix, the system load and the SNR. Compared to other recently-proposed methods, our proposed method offers a more efficient approach to finding the large-system performance by introducing a new expression for the covariance matrix of the interference term. A simplified multistage scheme to estimate the multipath channel gains is also introduced. It will be shown that by applying this new method for data detection and channel estimation, the performance of the MLMU receiver will converge to that of the minimum mean-squared error (MMSE) receiver.

Download or read book Dissertation Abstracts International written by and published by . This book was released on 2007 with total page 854 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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.

Download or read book Design of Interference cancellation Receiver for CDMA with MIMO system written by Dr.P.Sreesudha, and published by Archers & Elevators Publishing House. This book was released on with total page 73 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Conference Record written by and published by . This book was released on 2001 with total page 820 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Parallel Interference Cancellation Multiuser Detection written by Donald Richard Brown and published by . This book was released on 2000 with total page 442 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interference Cancellation for Short code DS CDMA in the Presence of Channel Fading written by Amit K. Dutta and published by . This book was released on 1997 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt: Interference from other adjacent users in wireless applications is a major problem in direct-sequence code-division multiple-access (DS-CDMA). This is also known as the near-far problem where a strong signal from one user interferes with other users. The current approach to deal with the near-far problem in DS-CDMA systems is to use strict transmitter power control. An alternative approach is to use near-far resistant receivers. The practical near-far resistance receiver structure is the adaptive decorrelating detectors since it avoids complex matrix inversion. The existing CDMA standard known as IS-95 uses a long signature code sequence. However for simplicity, the adaptive multi-user receiver uses short signature code sequence. The problem is that adaptive receivers lose near-far resistance as the number of users increases in the system. This thesis describes a novel method of multistage decision feedback cancellation (DFC) scheme immune from the near-far problem. The performance of the new DFC structure is constructed using three different adaptive algorithms: the least mean squared (LMS), the recursive least squared (RLS) and the linearly constraint constant modulus (LCCM) adaptive algorithms. It is found that LMS adaptive algorithm provides the best result considering its simple hardware complexity. It is also found that the LMS adaptive receiver along with the DFC structure provides a better bit synchronization capability to the over all system. Since the receiver is near-far resistant, the LMS adaptive receiver along with the decision feedback cancellation structure also performs better in the presence of Rayleigh fading.

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.

Download or read book Performance Analysis of a Multi code Multi carrier CDMA Communication System written by Jin Woo Lee and published by . This book was released on 2004 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Large System Performance of Linear Interference Suppression for DS CDMA written by Weimin Xiao and published by . This book was released on 2001 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: The performance of linear filtering is studied for the suppression of multiple access interference in a Direct-Sequence Code-Division Multiple Access (DS-CDMA) system with random spreading sequences. Both full-rank and reduced-rank filters are investigated. The emphasis of our study is on large system performance analysis.

Download or read book On the Adaptive Multi stage Detector for Cancellation of Multiuser Interference in CDMA Wireless Communication Systems written by Nadir Sezgin and published by . This book was released on 1996 with total page 168 pages. Available in PDF, EPUB and Kindle. Book excerpt: The classical multiple access techniques such as Frequency Division Multiple Access (FDMA) and Time Division Multiple Access (TDMA) schemes are band limited in terms of their capacity to be used for mobile radio communication. Recent developments in the area of digital signal processing, makes Code Division Multiple Access (CDMA) as a possible solution to the demand of capacity for the mobile radio communication. The capacity of CDMA is limited by multiuser interference, that is the interference from the other users. The goal of this dissertation is to improve the multiuser CDMA detector with high Bit Error Rate (BER) performance, low complexity, near-fax resistance as well as flexibility to be applied to a wide range of communication channels. We developed an adaptive multi-stage CDMA detector to cancel the multiuser interference. The first-stage of the detector, called decorrelating detector, decorrelates the correlated signals obtained at the match filter bank. The second-stage, called canceller, cancels the multiuser interference exist in the desired signals, using the decorrelated user signals obtained at the decorrelating detector output. The key future of this multi-stage detector is being purely adaptive. The combination of adaptive decorrelating detector and adaptive canceller allows the multi-stage detector achieve near-optimum BER performance and at the same time remain computationally effective. To increse achievable BElT performance an adaptive soft limiter is used at the canceller stage. The underlying structure of this multi-stage detector (i.e. being purely adaptive) allows it to be applied to different channel characteristics. However, throughout this dissertation we use Additive White Gaussian Noise (AWG N) channel for simplicity. To address some of the potential problems that may arise in practice, the adaptive decorrelating detector is tested using computer simulation and in-depth analysis of the problem. If necessary, an alternative solution that do not change the main characteristics of the detector (such as adaptivity and simplicity) is provided. Overall, we conclude that our adaptive detector with its high BER performance and adaptation ability to different channel characteristics, can be considered as an alternative solution to the problem of multiuser interference cancellation in CDMA communication.

Download or read book Conference Proceedings written by and published by . This book was released on 2003 with total page 782 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Enabling Technologies for 3G and Beyond written by Vijay Kumar Garg and published by SPIE-International Society for Optical Engineering. This book was released on 2001 with total page 174 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Interference Cancelling Receivers with Multiple Antennas for CDMA Systems written by Vafa Ghazi-Moghadam and published by . This book was released on 1997 with total page 266 pages. Available in PDF, EPUB and Kindle. Book excerpt: