Download or read book Adaptive Semi blind Channel Estimation Associated with Power Method for Hybrid Non zero Padding Assisted Space time Block Coded Mimo cdma Systems written by and published by . This book was released on 2013 with total page 128 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book A Study on Blind and Semiblind Detection for MIMO Systems and ARQ Retransmissions written by Muhammad Zia and published by . This book was released on 2010 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: We investigate blind and semi-blind channel estimation and detection techniques for multiple-input multiple-output (MIMO) communication systems. MIMO is an emerging technology that provides significant capacity and throughput gain over single-input single-output (SISO) systems without increase in bandwidth and power. To achieve these gains, typically, it requires pilot assisted channel estimation at the cost of bandwidth and power efficiency. Blind and semi-blind channel estimation or direct data detection techniques provide viable alternatives. We begin with blind zero-forcing (ZF) detection of Space-Time Block (STB) coded signal for MIMO systems over flat-fading channels for single user systems. We propose linear programming-based blind ZF equalization algorithm. Our method is globally convergent. We exploit redundancy and the implicit structure of space-time block codes to cast the problem into a low complexity linear programming. Unlikeseveral known methods, the proposed technique is applicable to full-rate space-time block codes such as the popular Alamouti orthogonal code and the quasi-orthogonal space time code. For orthogonal space-time codes, our LP algorithm achieves near maximum likelihood detection of orthogonal codes without channel knowledge and does not impose any conditions on the number of receive antennas. We extend this work to blind detection of STB coded data for co-channel synchronous multiuser MIMO system. We propose a globally convergent algorithm for the blind detection of co-channel multiuser signals under synchronous orthogonal space-time block coded modulation. We exploit the algebraic structure of the orthogonal space-time block codes and the Quadrature Amplitude Modulation (QAM) signal constellation to derive a quadratic programming (QP) algorithm that achieves desired convergence without the aid of training pilots. Focusing on the high rate space-time block codes in a synchronous co-channel multiuser system, we propose a successive processing strategy based on the proposed blind zero forcing (ZF) detector which has low computational complexity and fast convergence. Furthermore, our QP receiver for multiuser detection imposes less stringent conditions on the number of receive antennas of the multi-input-multi-output (MIMO) system. After investigating blind detection of STB coded signals for single and multiuser MIMO system, we focus on bandwidth and power efficient Hybrid Automatic Repeat reQuest (HARQ) at the physical layer level. The concept of HARQ is adapted in Long Term Evolution (LTE) and WiMAX standard and both standards consider full retransmission of the original copy of the original information. The physical layer performs joint detection called diversity combining. We propose retransmission of partial copy of original message and omit pilot symbols during retransmission. Our receiver jointly estimates channel of the both transmissions in semi-blind fashion. The joint detection of two transmissions improves overall performance of the receiver. We demonstrate bandwidth savings without significant performance loss and mild increase in complexity.
Download or read book Blind Channel Estimation for Orthogonal Space time Block Coded MIMO OFDM Systems written by 江建達 and published by . This book was released on 2013 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Signal Processing Channel Estimation and Link Adaptation in MIMO OFDM Systems written by Jianjun Ran and published by Cuvillier Verlag. This book was released on 2008 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Blind and Semi blind Channel Estimation Under Space time Coded Transmissions written by Nejib Ammar and published by . This book was released on 2005 with total page 340 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Hybrid Pre coded ST BC MIMO CDMA System with Semi blind Channel Estimation written by 廖聰智 and published by . This book was released on 2011 with total page 166 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book An EM based Channel Estimation Algorithm for Space Time Block Coded MIMO OFDM Systems written by Haideh M. Karkhanechi and published by . This book was released on 2007 with total page 290 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Semi Blind Channel Estimation Using Second Order Statistics and Its Application to Time Reversal Space Time Block Codes written by Hemanth Mullar Srikantaiah and published by . This book was released on 2006 with total page 86 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Low Complexity Adaptive Semi blind Space time Block Code MIMO CDMA Receiver Design written by Yu-Chia Chen and published by . This book was released on 2015 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book New Low Complexity Space time Coded MIMO CDMA System Design With Semi Blind Channel Estimation in Multipath Channel written by 洪毓謙 and published by . This book was released on 2010 with total page 130 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Adaptive Filtering Applications written by Lino Garcia Morales and published by IntechOpen. This book was released on 2011-07-05 with total page 412 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive filtering is useful in any application where the signals or the modeled system vary over time. The configuration of the system and, in particular, the position where the adaptive processor is placed generate different areas or application fields such as: prediction, system identification and modeling, equalization, cancellation of interference, etc. which are very important in many disciplines such as control systems, communications, signal processing, acoustics, voice, sound and image, etc. The book consists of noise and echo cancellation, medical applications, communications systems and others hardly joined by their heterogeneity. Each application is a case study with rigor that shows weakness/strength of the method used, assesses its suitability and suggests new forms and areas of use. The problems are becoming increasingly complex and applications must be adapted to solve them. The adaptive filters have proven to be useful in these environments of multiple input/output, variant-time behaviors, and long and complex transfer functions effectively, but fundamentally they still have to evolve. This book is a demonstration of this and a small illustration of everything that is to come.
Download or read book Blind Channel Estimation and Single user Detection for Multi carrier and Spread spectrum Systems with Transmit Diversity written by Shahrokh Nayeb Nazar and published by . This book was released on 2008 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "The application of transmit diversity techniques such as Space-Time Block Coding (STBC) to the downlink of multiuser wireless communications systems has received considerable attention. The main advantage of such an approach is its ability to provide diversity gains through the use of multiple antennas only at the transmitting side without significantly increasing the complexity at the receiving end. Among the many multiple access techniques proposed, Multi-Carrier (MC) and Direct Sequence (DS) Code Division Multiple Access (CDMA) techniques are known as the most promising candidates for future broadband mobile communication networks. In MC and DS-CDMA systems or combination thereof, employing transmit diversity, the spatial diversity gains can only be realized if the underlying channels are accurately acquired at the receiver. Furthermore, such systems suffer from high computational complexity which should be properly addressed for practical implementations. Motivated by these observations, in the first part of this dissertation, we introduce the chip-level ST block coding scheme for DS-CDMA systems. For this scheme, we address the problems of single-user detection as well as blind channel estimation, and we show that chip-level coding does not suffer from antenna order ambiguity. Moreover, we demonstrate that chip-level schemes exhibit low decoding delay and allow for the design of adaptive single-user detectors with improved short data-record performance characteristics compared to their symbol-level counterparts. In the second part of this dissertation, we present a novel transmission scheme for the downlink of MC-CDMA systems with transmit diversity that is based on chip-level Space-Frequency (SF) block coding. For this scheme, we investigate the problem of blind channel estimation when the received signal processing is done (i) pre-Fast Fourier Transform (FFT); and (ii) post-FFT. We propose two blind channel estimation algorithms based on subspace and Minimum Variance Distortionless Response (MVDR) principles. Moreover, we present an analytical performance analysis of the proposed algorithms by investigating the bias as well as the finite data record mean-square error of the channel estimates. Our analysis shows that SFBC MC-CDMA systems do not suffer from antenna order ambiguity. In addition, to benchmark the accuracy of our estimation algorithms, we derive the corresponding Cramer-Rao bounds (CRB) based on a novel approach that assumes the knowledge of only the spreading code of the desired user. Our approach has the advantage of providing lower bounds which are tighter than the CRBs with known signatures. We also study the problem of single user detection for downlink transmissions to address the issue of multiuser interference. In the case of the post-FFT approach, we take advantage of the SFBC-induced signal structure to derive linear single-user detectors with improved performance in short data-record situations. Finally, in order to address the issue of computational complexity, we exploit the structure of the covariance matrix of the received signal to simplify the computations involved in estimating the channel, and forming the detector."--
Download or read book Signal perturbation free Semi blind Channel Estimation for MIMO OFDM Systems written by Feng Wan and published by . This book was released on 2009 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input multiple-output orthogonal frequency division multiplexing (MIMO-OFDM) has been considered as a strong candidate for the beyond 3G (B3G) wireless communication systems, due to its high data-rate wireless transmission performance. It is well known that the advantages promised by MIMO-OFDM systems rely on the precise knowledge of the channel state information (CSI). In real wireless environments, however, the channel condition is unknown. Therefore, channel estimation is of crucial importance in MIMO-OFDM systems. Semi-blind channel estimation as a combination of the training-based or pilot-assisted method and the pure blind approach is considered to be a feasible solution for practical wireless systems due to its better estimation accuracy as well as spectral efficiency. In this thesis, we address the semi-blind channel estimation issue of MIMO-OFDM systems with an objective to develop very efficient channel estimation approaches. In the first part of the dissertation, several nulling-based semi-blind approaches are presented for the estimation of time-domain MIMO-OFDM channels. By incorporating a blind constraint that is derived from MIMO linear prediction (LP) into a training-based least-square method, a semi-blind solution for the time-domain channel estimation is first obtained. It is revealed through a perturbation analysis that the semi-blind solution is not subject to signal perturbation and therefore is superior to pure blind estimation methods. The LP-based semi-blind method is then extended for the channel estimation of MIMO-OFDM systems with pulse-shaping. By exploiting the pulse-shaping filter in the transmitter and the matched filter in the receiver, a very efficient semi-blind approach is developed for the estimation of sampling duration based multipath channels. A frequency-domain correlation matrix estimation algorithm is also presented to facilitate the computation of time-domain second-order statistics required in the LP-based method. The nulling-based semi-blind estimation issue of sparse MIMO-OFDM channels is also addressed. By disclosing and using a relationship between the positions of the most significant taps (MST) of the sparse channel and the lags of nonzero correlation matrices of the received signal, a novel estimation approach consisting of the MST detection and the sparse channel estimation, both in a semi-blind fashion, is developed. An intensive simulation study of all the proposed nulling-based methods with comparison to some existing techniques is conducted, showing a significant superiority of the new methodologies. The second part of the dissertation is dedicated to the development of two signal-perturbation-free (SPF) semi-blind channel estimation algorithms based on a novel transmit scheme that bears partial information of the second-order statistics of the transmitted signal to receiver. It is proved that the new transmit scheme can completely cancel the signal perturbation error in the noise-free case, thereby improving largely the estimation accuracy of correlation matrix for channel estimation in noisy conditions. It is also shown that the overhead caused by the transmission of the 8PF data is negligible as compared to that of regular pilot signals. By using the proposed transmit scheme, a whitening rotation (WR)-based algorithm is first developed for frequency-domain MIMO-OFDM channel estimation. It is shown through both theoretical analysis and simulation study that the new WR-based algorithm significantly outperforms the conventional WR-based method and the nulling-based semi-blind method. By using MIMO linear prediction, the new WR-based algorithm utilizing the 8PF transmit scheme is then extended for time-domain MIMO-OFDM channel estimation. Computer simulations show that the proposed signal-perturbation-free LP-based semi-blind solution performs much better than the LP semi-blind method without using the proposed transmit scheme, the LS method as well as the nulling-based semi-blind method in terms of the MSE of the channel estimate.
Download or read book Adaptive Semiblind Channel Estimation for OFDM OQAM Systems written by Tianze Su and published by . This book was released on 2016 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: "In this thesis, we propose and investigate novel adaptive semi-blind channel estimation algorithms for OFDM/OQAM systems. OFDM/OQAM is regarded as a promising alternative to conventional CP-OFDM for multi-carrier modulation since it can provide better spectrum efficiency, albeit at the price of increased complexity. We first formulate a general system model of an OFDM/OQAM transceiver. Based on this model, we review a recently proposed block based semi-blind channel estimation method for OFDM/OQAM systems, known as the sign covariance matrix (SCM) method. This method mainly exploits the higher-order statistical properties of the data at the receiver side but is not well-suited for applications to time-varying channels. Subsequently, to overcome the drawbacks of this block-based technique, we propose adaptive semi-blind channel estimation algorithms for application to OFDM/OQAM. The proposed algorithms consist of an adaptive SCM technique obtained through exponential recursive averaging, as well as several constant modulus algorithms (CMA) for recursive estimation. Although all the adaptive algorithms are designed to deal with time-varying channels, they can also be used for rapid channel acquisition in the case of static or slowly-varying channels. Furthermore, we explore the coherence bandwidth of the channel and make use of this concept to improve the estimation accuracy via a frequency averaging technique that can be combined with the adaptive SCM. Simulation results validate the efficacy of the proposed adaptive estimation algorithms over both time-invariant and varying channels, showing their robustness in terms of convergence speed, tracking capability and residual estimation error in steady-state. In particular, the CMA with recursive least squares (CMA-RLS) updating proves to be the most preferable due to its excellent trade-off between convergence rate and residual error level. The CMA-RLS also offers the best performance in tracking a time-varying channel. In addition, simulation experiments demonstrate the effectiveness of combining the frequency averaging technique with the proposed adaptive SCM algorithm." --
Download or read book Generalized Subspace based Blind Channel Estimation Algorithm in MIMO Zero padded Block Transmission Systems written by 易宗陽 and published by . This book was released on 2011 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book MIMO OFDM Wireless Communications with MATLAB written by Yong Soo Cho and published by John Wiley & Sons. This book was released on 2010-08-20 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: MIMO-OFDM is a key technology for next-generation cellular communications (3GPP-LTE, Mobile WiMAX, IMT-Advanced) as well as wireless LAN (IEEE 802.11a, IEEE 802.11n), wireless PAN (MB-OFDM), and broadcasting (DAB, DVB, DMB). In MIMO-OFDM Wireless Communications with MATLAB®, the authors provide a comprehensive introduction to the theory and practice of wireless channel modeling, OFDM, and MIMO, using MATLAB® programs to simulate the various techniques on MIMO-OFDM systems. One of the only books in the area dedicated to explaining simulation aspects Covers implementation to help cement the key concepts Uses materials that have been classroom-tested in numerous universities Provides the analytic solutions and practical examples with downloadable MATLAB® codes Simulation examples based on actual industry and research projects Presentation slides with key equations and figures for instructor use MIMO-OFDM Wireless Communications with MATLAB® is a key text for graduate students in wireless communications. Professionals and technicians in wireless communication fields, graduate students in signal processing, as well as senior undergraduates majoring in wireless communications will find this book a practical introduction to the MIMO-OFDM techniques. Instructor materials and MATLAB® code examples available for download at www.wiley.com/go/chomimo
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.
