Download or read book Efficient Detection and Scheduling for MIMO OFDM Systems written by Wei Liu and published by . This book was released on 2012 with total page 100 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input multiple-output (MIMO) antennas can be exploited to provide high data rate using a limited bandwidth through multiplexing gain. MIMO combined with orthogonal frequency division multiplexing (OFDM) could potentially provide high data rate and high spectral efficiency in frequency-selective fading channels. MIMO-OFDM technology has been widely employed in modern communication systems, such as Wireless Local Area Network (WLAN), Long Term Evolution (LTE) and Worldwide Interoperability for Microwave Access (WiMAX). However, most of the conventional schemes either are computationally prohibitive or underutilize the full performance gain provided by the inherent merits of MIMO and OFDM techniques. In the first part of this dissertation, we firstly study the channel matrix inversion which is commonly required in various MIMO detection schemes. An algorithm that exploits second-order extrapolation in the time domain is proposed to efficiently reduce the computational complexity. This algorithm can be applied to both linear detection and non-linear detection such as ordered successive interference cancellation (OSIC) while maintaining the system performance. Secondly, we study the complexity reduction for Lattice Reduction Aided Detection (LRAD) of MIMO-OFDM systems. We propose an algorithm that exploits the inherent feature of unimodular transformation matrix that remains the same for relatively highly correlated frequency components. This algorithm effectively eliminates the redundant brute-force lattice reduction iterations among adjacent subcarriers. Thirdly, we analyze the impact of channel coherence bandwidth on two LRAD algorithms. Analytical and simulation results demonstrate that carefully setting the initial calculation interval according to the coherence bandwidth is essential for both algorithms. The second part of this dissertation focuses on efficient multi-user (MU) scheduling and coordination for the uplink of WLAN that uses MIMO-OFDM techniques. On one hand, conventional MU-MIMO medium access control (MAC) protocols require large overhead, which lowers the performance gain of concurrent transmissions rendered by the multi-packet reception (MPR) capability of MIMO systems. Therefore, an efficient MU-MIMO uplink MAC scheduling scheme is proposed for future WLAN. On the other hand, single-user (SU) MIMO achieves multiplexing gain in the physical (PHY) layer and MU-MIMO achieves multiplexing gain in the MAC layer. In addition, the average throughput of the system varies depending on the number of antennas and users, average payload sizes, and signal-to-noise-ratios (SNRs). A comparison on the performance between SU-MIMO and MU-MIMO schemes for WLAN uplink is hence conducted. Simulation results indicate that a dynamic switch between the SU-MIMO and MU-MIMO is of significance for higher network throughput of WLAN uplink.

Download or read book Efficient Detection and Adaptive Transmission for MIMO OFDM Systems written by Ronald Böhnke and published by . This book was released on 2014 with total page 255 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Wireless MIMO OFDM Systems with Coherent and Non Coherent Detection written by Alexander Vanaev and published by Cuvillier Verlag. This book was released on 2013-02-05 with total page 206 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis the physical layer design of broadband MIMO-OFDM communication systems is considered taking into account the realistic multipath radio channel. The main focus is made on examining a number of coherent and non-coherent MIMO techniques both analytically and via computer simulations. Several proposals are made to assist intelligent selection of MIMO precoding and decoding algorithms. Additionally two novel improved differential transmission schemes are presented and analyzed. In dieser Arbeit wird der Entwurf der physikalischen Schicht für breitbandige MIMO-OFDM Kommunikationssysteme betrachtet. Dazu werden realistische Funkkanalmodelle mit Mehrwegeausbreitung berücksichtigt. Ein wesentlicher Schwerpunkt der Arbeit liegt auf Untersuchungen zu kohärenten und nichtkohärenten MIMO-Techniken, die sowohl analytisch als auch mit Hilfe von Computersimulationen durchgeführt werden. Es werden verschiedene Vorschläge erarbeitet, wie eine intelligente Auswahl von MIMO-Techniken zur Vorcodierung sowie zur Decodierung getroffen werden kann. Darüber hinaus werden zwei neuartige, verbesserte differentielle Übertragungsverfahren vorgestellt und analysiert.

Download or read book Semi Blind Signal Detection for Mimo and Mimo Ofdm Systems written by Shaodan Ma and published by Open Dissertation Press. This book was released on 2017-01-27 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation, "Semi-blind Signal Detection for MIMO and MIMO-OFDM Systems" by Shaodan, Ma, 馬少丹, 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. Abstract: Abstract of thesis entitled "Semi-Blind Signal Detection for MIMO and MIMO-OFDM Systems" Submitted by Ma Shaodan for the degree of Doctor of Philosophy at The University of Hong Kong in May 2006 MIMO (Multiple Input Multiple Output) and MIMO-OFDM (Orthogonal Frequency Division Multiplexing) systems have attracted a lot of research interest in recent years due to their potential for future high speed wireless communications. This thesis focuses on the problem of signal detection and proposes three semi-blind algorithms for MIMO, MIMO-OFDM with short cyclic prefix (CP), and MIMO- OFDM without CP, respectively. A three-step semi-blind Rake-based multi-user detection technique is proposed for quasi-synchronous MIMO systems. The first step separates the multi-user multi-path signal vector into multi-user single-path signal vectors based on second-order statistics (SOS) of the received signals. A simple estimation method is proposed in the second step to estimate the time delays with the aid of pilots. The third step combines multiple multi-user single-path signal vectors for signal detection. System performance is improved by time diversity and only the upper bounds of the channel length and the time delays are required. Simulation results show that the proposed technique achieves good performance and is not sensitive to over-estimation of the maximum channel length and the maximum time delay. A MIMO-OFDM system with short CP is next considered for higher bandwidth efficiency and a time domain semi-blind signal detection algorithm is proposed. A new system model in which the i th received OFDM symbol is left shifted by J samples is introduced. Based on some structural properties of the new system model, an equalizer is designed using SOS of the received signals to cancel most of the inter- symbol interference (ISI). The transmitted signals are then detected from the equalizer output. In the proposed algorithm, only 2P ( P is the number of transmit antennas/users in MIMO-OFDM systems) columns of the channel matrix need to be estimated, and channel length estimation is unnecessary. In addition, the proposed algorithm is applicable irrespective of whether the channel length is shorter than, equal to or longer than the CP length. Simulation results verify the effectiveness of the proposed algorithm, and show that it outperforms the existing ones in all cases. Finally, in order to further improve bandwidth efficiency, a MIMO-OFDM system without CP is considered and a two-step semi-blind signal detection algorithm is proposed. The algorithm is based on some structural properties derived from shifting the received OFDM symbols. The first step cancels inter-carrier interference (ICI) and ISI with an equalizer designed using SOS of the shifted received OFDM symbols. The second step involves signal detection from the equalizer output in which the signals are still corrupted with multi-antenna interference (MAI). In the proposed algorithm, precise knowledge of the channel length is unnecessary and only one pilot OFDM symbol is utilized to estimate the required channel state information. Simulation results show that the proposed algorithm achieves comparable performance to algorithms for standard MIMO-OFDM systems and it is robust against channel length overestimation. The number of words: 460 DOI: 10.5353/th_b3684656 Subjects: Signal detection Algorithms MIMO systems Orthogonal

Download or read book Channel Estimation and Data Detection for Mobile MIMO OFDM Systems written by Jie Gao and published by . This book was released on 2005 with total page 210 pages. Available in PDF, EPUB and Kindle. Book excerpt: Designing spectral efficient, high-speed wireless links that offer high quality- of-service and range capability has been a critical research and engineering challenge. In this thesis, we mainly address the complexity and performance issues of channel estimation and data detection in multiple-input multiple-output (MIMO) orthogonal frequency division multiplexing (OFDM) systems over time-varying channels. We derive the probability density function (pdf) expressions of the condition number (i.e., the maximum-to-minimum-singular-value ratio, MMSVR) of the channel state information matrix of MIMO OFDM systems. It is shown that this ratio is directly related to the noise enhancement in open-loop systems and provides a significant insight on the system capacity. A decision-directed (DD) maximum a posteriori probability (MAP) channel estimation scheme of MIMO systems is derived. Error performance of a zero- forcing receiver with the DD MAP and perfect channel estimates is provided and compared. This scheme has a low complexity and can be applied to time-varying Rayleigh fading channels with an arbitrary spaced-time correlation function. We propose an iterative channel estimation and data detection scheme for MIMO OFDM systems in the presence of inter-carrier-interference (ICI) due to the nature of time-varying channels. An ICI-based minimum-mean-square error (MMSE) detection scheme is derived. An expectation-maximization (EM) based least square (LS) channel estimator is proposed to minimize the mean-square error (MSE) of the channel estimates and to reduce the complexity of the implementation. With the estimate of the channel and initially detected symbols, ICI is estimated and removed from the received signal. Thus more accurate estimation of the channel and data detection can be obtained in the next iteration. An EM-based MAP channel estimator is derived by exploiting the frequency/time correlation of the pilot and data sub-carriers. Performance comparison is made between the proposed schemes and the ideal case - time-invariant channels and perfect channel estimation. We optimize the data transmission by exploiting the long term correlation characteristics. The transmitted data is successively detected without an error floor in spatially correlated channels. The algorithms proposed in this thesis allow low-complexity implementation of channel estimation and data detection for MIMO OFDM systems over time-varying fading channels, while providing good error performance.

Download or read book Multi Carrier Systems Solutions 2009 written by Simon Plass and published by Springer Science & Business Media. This book was released on 2009-04-26 with total page 392 pages. Available in PDF, EPUB and Kindle. Book excerpt: The 7th International Workshop on Multi-Carrier Systems and Solutions was held in May 2009. In providing the proceedings of that conference, this book offers comprehensive, state-of-the-art articles about multi-carrier techniques and systems.

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 Narrowband MIMO and MIMO OFDM Systems written by Eunmo Kang and published by . This book was released on 2010 with total page 105 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Coding for MIMO OFDM in Future Wireless Systems written by Bannour Ahmed and published by . This book was released on 2015 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: This book introduces the reader to the MIMO-OFDM system, in Rayleigh frequency selective-channels. Orthogonal frequency division multiplexing (OFDM) has been adopted in the wireless local-area network standards IEEE 802.11a due to its high spectral efficiency and ability to deal with frequency selective fading. The combination of OFDM with spectral efficient multiple antenna techniques makes the OFDM a good candidate to overcome the frequency selective problems.

Download or read book Low Complexity MIMO Detection written by Lin Bai and published by Springer Science & Business Media. This book was released on 2012-01-07 with total page 251 pages. Available in PDF, EPUB and Kindle. Book excerpt: Low Complexity MIMO Detection introduces the principle of MIMO systems and signal detection via MIMO channels. This book systematically introduces the symbol detection in MIMO systems. Includes the fundamental knowledge of MIMO detection and recent research outcomes for low complexity MIMO detection.

Download or read book A Cognitive MIMO OFDM Detector Design for Computationally Efficient Space Time Decoding written by Mitchell J. Grabner and published by . This book was released on 2019 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation a computationally efficient cognitive multiple-input multiple-output (MIMO) orthogonal frequency division duplexing (OFDM) detector is designed to decode perfect space-time coded signals which are able maximize the diversity and multiplexing properties of a rich fading MIMO channel. The adaptive nature of the cognitive detector allows a MIMO OFDM communication system to better meet to needs of future wireless communication networks which require both high reliability and low run-time complexity depending on the propagation environment. The cognitive detector in conjunction with perfect space-time coding is able to achieve up to a 2 dB bit-error rate (BER) improvement at low signal-to-noise ratio (SNR) while also achieving comparable runtime complexity in high SNR scenarios.

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 EFFECTIVE SPARSE CHANNEL ESTIMATION TECHNIQUE FOR MIMO OFDM SYSTEM written by Dr.Maddala Vijayalakshmi and published by Archers & Elevators Publishing House. This book was released on with total page 58 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Overhead Efficient Algorithms for Acquisition written by Christian Oberli and published by . This book was released on 2004 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MIMO OFDM for LTE WiFi and WiMAX written by Lajos Hanzo and published by John Wiley & Sons. This book was released on 2012-01-03 with total page 693 pages. Available in PDF, EPUB and Kindle. Book excerpt: MIMO-OFDM for LTE, WIFI and WIMAX: Coherent versus Non-Coherent and Cooperative Turbo-Transceivers provides an up-to-date portrayal of wireless transmission based on OFDM techniques augmented with Space-Time Block Codes (STBCs) and Spatial-Division Multiple Access (SDMA). The volume also offers an in-depth treatment of cutting-edge Cooperative Communications. This monograph collates the latest techniques in a number of specific design areas of turbo-detected MIMO-OFDM wireless systems. As a result a wide range of topical subjects are examined, including channel coding and multiuser detection (MUD), with a special emphasis on optimum maximum-likelihood (ML) MUDs, reduced-complexity genetic algorithm aided near-ML MUDs and sphere detection. The benefits of spreading codes as well as joint iterative channel and data estimation are only a few of the radical new features of the book. Also considered are the benefits of turbo and LDPC channel coding, the entire suite of known joint coding and modulation schemes, space-time coding as well as SDM/SDMA MIMOs within the context of various application examples. The book systematically converts the lessons of Shannon's information theory into design principles applicable to practical wireless systems; the depth of discussions increases towards the end of the book. Discusses many state-of-the-art topics important to today's wireless communications engineers. Includes numerous complete system design examples for the industrial practitioner. Offers a detailed portrayal of sphere detection. Based on over twenty years of research into OFDM in the context of various applications, subsequently presenting comprehensive bibliographies.

Download or read book Efficient Channel State Information CSI Feedback for Close loop MIMO OFDM Systems written by 陳維廷 and published by . This book was released on 2014 with total page 47 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