Download or read book Design and Analysis of MIMO Systems with Practical Channel State Information Assumptions written by Jun Zheng and published by . This book was released on 2006 with total page 228 pages. Available in PDF, EPUB and Kindle. Book excerpt: Using multiple antennas at both the transmitter and the receiver is one of the most promising techniques that can offer significant increases in channel capacity of a communication system in a wireless fading environment. However, the performance of the MIMO system depends heavily upon the availability of the channel state information (CSI) at the transmitter (CSIT) and at the receiver (CSIR). In this dissertation, we focus our attention on the design and analysis of MIMO systems over wireless fading channels with practical CSI assumptions, which can broadly be divided into the following two categories. The first part considers the development of a general framework for the analysis of multiple antenna systems with finite-rate feedback, wherein the CSI is quantized at the receiver and conveyed back to the transmitter through a rate-constrained reverse link. Inspired by the results of classical high resolution quantization theory, the problem of finite rate quantized communication system is formulated as a general fixed-rate vector quantization problem with side information available at the encoder (or the quantizer) but unavailable at the decoder. The framework of the quantization problem is sufficiently general to include quantization schemes with general non-mean square distortion functions, and constrained source vectors. Asymptotic distortion analysis of the proposed general quantization problem is provided by extending the vector version of the Bennett's integral. Specifically, tight lower and upper bounds of the average asymptotic distortion are provided together with useful insights from a source coding perspective. The proposed general methodology provides a powerful analytical tool to study a wide range of finite-rate feedback systems which includes both MISO systems over spatially correlated fading channels and MIMO systems over i.i.d. fading channels. The established framework is also versatile enough to provide analysis of sub-optimal mismatched CSI quantizers and quantizers with transformed codebooks. The second part of this dissertation is focused the on the design and analysis of MIMO systems over fading channels with CSI unavailable both at the transmitter and at the receiver. To be specific, we first provide an improved capacity lower bound for MIMO systems with unknown CSI. By analyzing (and optimizing) the proposed capacity lower bound with respect to different system parameters, we improve our intuition and understanding of the effects of training on the overall performance of MIMO systems under unknown CSI assumptions. Moreover, based on the capacity analysis results, we also provide the design of practical LDPC-coded MIMO systems under the same unknown CSI assumption at both component level and structural level. We first propose at the component level several soft-input soft-output MIMO detectors whose performances are much better than the conventional MMSE-based detectors. At the structural level, an unconventional iterative decoding scheme is proposed whose structure leads to a simple and efficient LDPC code degree profile optimization algorithm with proven global optimality and guaranteed convergence from any initialization.
Download or read book Massive MIMO written by Hien Quoc Ngo and published by Linköping University Electronic Press. This book was released on 2015-01-16 with total page 69 pages. Available in PDF, EPUB and Kindle. Book excerpt: The last ten years have seen a massive growth in the number of connected wireless devices. Billions of devices are connected and managed by wireless networks. At the same time, each device needs a high throughput to support applications such as voice, real-time video, movies, and games. Demands for wireless throughput and the number of wireless devices will always increase. In addition, there is a growing concern about energy consumption of wireless communication systems. Thus, future wireless systems have to satisfy three main requirements: i) having a high throughput; ii) simultaneously serving many users; and iii) having less energy consumption. Massive multiple-input multiple-output (MIMO) technology, where a base station (BS) equipped with very large number of antennas (collocated or distributed) serves many users in the same time-frequency resource, can meet the above requirements, and hence, it is a promising candidate technology for next generations of wireless systems. With massive antenna arrays at the BS, for most propagation environments, the channels become favorable, i.e., the channel vectors between the users and the BS are (nearly) pairwisely orthogonal, and hence, linear processing is nearly optimal. A huge throughput and energy efficiency can be achieved due to the multiplexing gain and the array gain. In particular, with a simple power control scheme, Massive MIMO can offer uniformly good service for all users. In this dissertation, we focus on the performance of Massive MIMO. The dissertation consists of two main parts: fundamentals and system designs of Massive MIMO. In the first part, we focus on fundamental limits of the system performance under practical constraints such as low complexity processing, limited length of each coherence interval, intercell interference, and finite-dimensional channels. We first study the potential for power savings of the Massive MIMO uplink with maximum-ratio combining (MRC), zero-forcing, and minimum mean-square error receivers, under perfect and imperfect channels. The energy and spectral efficiency tradeoff is investigated. Secondly, we consider a physical channel model where the angular domain is divided into a finite number of distinct directions. A lower bound on the capacity is derived, and the effect of pilot contamination in this finite-dimensional channel model is analyzed. Finally, some aspects of favorable propagation in Massive MIMO under Rayleigh fading and line-of-sight (LoS) channels are investigated. We show that both Rayleigh fading and LoS environments offer favorable propagation. In the second part, based on the fundamental analysis in the first part, we propose some system designs for Massive MIMO. The acquisition of channel state information (CSI) is very importantin Massive MIMO. Typically, the channels are estimated at the BS through uplink training. Owing to the limited length of the coherence interval, the system performance is limited by pilot contamination. To reduce the pilot contamination effect, we propose an eigenvalue-decomposition-based scheme to estimate the channel directly from the received data. The proposed scheme results in better performance compared with the conventional training schemes due to the reduced pilot contamination. Another important issue of CSI acquisition in Massive MIMO is how to acquire CSI at the users. To address this issue, we propose two channel estimation schemes at the users: i) a downlink "beamforming training" scheme, and ii) a method for blind estimation of the effective downlink channel gains. In both schemes, the channel estimation overhead is independent of the number of BS antennas. We also derive the optimal pilot and data powers as well as the training duration allocation to maximize the sum spectral efficiency of the Massive MIMO uplink with MRC receivers, for a given total energy budget spent in a coherence interval. Finally, applications of Massive MIMO in relay channels are proposed and analyzed. Specifically, we consider multipair relaying systems where many sources simultaneously communicate with many destinations in the same time-frequency resource with the help of a massive MIMO relay. A massive MIMO relay is equipped with many collocated or distributed antennas. We consider different duplexing modes (full-duplex and half-duplex) and different relaying protocols (amplify-and-forward, decode-and-forward, two-way relaying, and one-way relaying) at the relay. The potential benefits of massive MIMO technology in these relaying systems are explored in terms of spectral efficiency and power efficiency.
Download or read book Dissertation Abstracts International written by and published by . This book was released on 2008 with total page 994 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Optimizing Massive MIMO written by Hei Victor Cheng and published by Linköping University Electronic Press. This book was released on 2018-04-11 with total page 63 pages. Available in PDF, EPUB and Kindle. Book excerpt: The past decades have seen a rapid growth of mobile data traffic,both in terms of connected devices and data rate. To satisfy the evergrowing data traffic demand in wireless communication systems, thecurrent cellular systems have to be redesigned to increase both spectralefficiency and energy efficiency. Massive MIMO(Multiple-Input-Multiple-Output) is one solution that satisfy bothrequirements. In massive MIMO systems, hundreds of antennas areemployed at the base station to provide service to many users at thesame time and frequency. This enables the system to serve the userswith uniformly good quality of service simultaneously, with low-costhardware and without using extra bandwidth and energy. To achievethis, proper resource allocation is needed. Among the availableresources, transmit power beamforming are the most important degrees offreedom to control the spectral efficiency and energy efficiency. Dueto the use of excessive number of antennas and low-end hardware at thebase station, new aspects of power allocation and beamforming compared to currentsystems arises. In the first part of the thesis, new uplink power allocation schemes that based on long term channel statistics isproposed. Since quality of the channel estimates is crucial in massive MIMO, in addition to data power allocation, joint power allocationthat includes the pilot power as additional variable should be considered. Therefore a new framework for power allocation thatmatches practical systems is developed, as the methods developed in the literature cannot be applied directly to massive MIMO systems. Simulation results confirm the advantages brought by the the proposed new framework. In the second part, we introduces a new approach to solve the joint precoding and power allocation for different objective in downlink scenarios by a combination of random matrix theory and optimization theory. The new approach results in a simplified problem that, though non-convex, obeys a simple separable structure. Simulation results showed that the proposed scheme provides large gains over heuristic solutions when the number of users in the cell is large, which is suitable for applying in massive MIMO systems. In the third part we investigate the effects of using low-end amplifiers at the basestations. The non-linear behavior of power consumption in these amplifiers changes the power consumption model at the basestation, thereby changes the power allocation and beamforming design. Different scenarios are investigated and resultsshow that a certain number of antennas can be turned off in some scenarios. In the last part we consider the use of non-orthogonal-multiple-access (NOMA) inside massive MIMO systems in practical scenarios where channel state information (CSI) is acquired through pilot signaling. Achievable rate analysis is carried out for different pilot signaling schemes including both uplink and downlink pilots. Numerical results show that when downlink CSI is available at the users, our proposed NOMA scheme outperforms orthogonal schemes. However with more groups of users present in the cell, it is preferable to use multi-user beamforming in stead of NOMA.
Download or read book Channel Estimation and Non linear Transceiver Designs for MIMO OFDM Relay Systems written by Andrew Paul Millar and published by . This book was released on 2014 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input multiple output (MIMO) systems deploy multiple antennas at either end of a communication link and can provide significant benefits compared to traditional single antenna systems, such as increased data rates through spatial multiplexing gain, and/or improved link reliability through diversity techniques. Recently, the natural extension of utilising multiple antennas in relay networks, known as MIMO relaying, has attracted significant research attention due to the fact that the benefits of MIMO can be coupled with extended network coverage through the use of relaying devices. This thesis concentrates on the design and analysis of different aspects of MIMO relay systems communicating over frequency selective channels with the use of orthogonal frequency division multiplexing (OFDM). The first focus of this thesis is on the development of training based channel estimation algorithms for two-hop MIMO OFDM relaying. In the first phase of channel estimation the relay-destination channel is estimated using conventional point-to-point MIMO estimation techniques. In the second phase, the source sends known training symbols to the relay, which precodes the received symbols and forwards them to the destination. In order to estimate the source-relay channel at the destination, an iterative algorithm is derived, which involves sequentially solving a number of convex optimisation problems and has guaranteed convergence. Since the proposed iterative algorithm may be too computationally complex for practical systems, a simplified approach is also derived where the channel estimation processors can be calculated in closed form. Under the assumption of perfect channel state information (CSI), we then develop non-linear transceiver designs for MIMO OFDM relay systems, focusing specifically on decision feedback equalisation (DFE) and Tomlinson Harashima precoding (THP). The optimal source and relay precoding matrices are derived that minimise the arithmetic mean square error (MSE) subject to source and relay transmission power constraints, when either a zero forcing (ZF) or minimum mean square error (MMSE) equaliser is used at the destination. Simulation results demonstrate that the proposed non-linear solutions outperform linear transceivers in terms of bit error rate (BER) and MSE. For the case of imperfect CSI at all nodes, robust DFE and THP transceivers are then considered that aim to minimise the expected artithmetic MSE subject to the source and relay transmission power constraints. The channel estimation errors are modelled as being drawn from matrix variate Gaussian distributions with known mean and covariance. The source and relay precoder structures are derived for the case that the optimal MMSE equaliser is used at the destination. The derived precoder structures are shown to be optimal for the special case that the channel estimation errors are uncorrelated. Simulation results demonstrate the robustness of the proposed algorithms to channel estimation errors.
Download or read book Analysis and Transceiver Design for the MIMO Broadcast Channel written by Raphael Hunger and published by Springer Science & Business Media. This book was released on 2012-08-29 with total page 323 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book deals with the optimization-based joint design of the transmit and receive filters in MIMO broadcast channel in which the user terminals may be equipped with several antenna elements. Furthermore, the maximum performance of the system in the high power regime as well as the set of all feasible quality-of-service requirements is analyzed. First, a fundamental duality is derived that holds between the MIMO broadcast channel and virtual MIMO multiple access channel. This duality construct allows for the efficient solution of problems originally posed in the broadcast channel in the dual domain where a possibly hidden convexity can often be revealed. On the basis of the established duality result, the gradient-projection algorithm is introduced as a tool to solve constrained optimization problems to global optimality under certain conditions. The gradient-projection tool is then applied to solving the weighted sum rate maximization problem which is a central optimization that arises in any network utility maximization. In the high power regime, a simple characterization of the obtained performance becomes possible due to the fact that the weighted sum rate utility converges to an affine asymptote in the logarithmic power domain. We find closed form expressions for these asymptotes which allows for a quantification of the asymptotic rate loss that linear transceivers have to face with respect to dirty paper coding. In the last part, we answer the fundamental question of feasibility in quality-of-service based optimizations with inelastic traffic that features strict delay constraints. Under the assumption of linear transceivers, not every set of quality-of-service requirements might be feasible making the power minimization problem with given lower bound constraints on the rate for example infeasible in these cases. We derive a complete description of the quality-of-service feasibility region for arbitrary channel matrices.
Download or read book MIMO Wireless Communications written by Ezio Biglieri and published by Cambridge University Press. This book was released on 2007-01-08 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input multiple-output (MIMO) technology constitutes a breakthrough in the design of wireless communications systems, and is already at the core of several wireless standards. Exploiting multipath scattering, MIMO techniques deliver significant performance enhancements in terms of data transmission rate and interference reduction. This 2007 book is a detailed introduction to the analysis and design of MIMO wireless systems. Beginning with an overview of MIMO technology, the authors then examine the fundamental capacity limits of MIMO systems. Transmitter design, including precoding and space-time coding, is then treated in depth, and the book closes with two chapters devoted to receiver design. Written by a team of leading experts, the book blends theoretical analysis with physical insights, and highlights a range of key design challenges. It can be used as a textbook for advanced courses on wireless communications, and will also appeal to researchers and practitioners working on MIMO wireless systems.
Download or read book MIMO Systems written by Hossein Khaleghi Bizaki and published by BoD – Books on Demand. This book was released on 2011-04-04 with total page 504 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, it was realized that the MIMO communication systems seems to be inevitable in accelerated evolution of high data rates applications due to their potential to dramatically increase the spectral efficiency and simultaneously sending individual information to the corresponding users in wireless systems. This book, intends to provide highlights of the current research topics in the field of MIMO system, to offer a snapshot of the recent advances and major issues faced today by the researchers in the MIMO related areas. The book is written by specialists working in universities and research centers all over the world to cover the fundamental principles and main advanced topics on high data rates wireless communications systems over MIMO channels. Moreover, the book has the advantage of providing a collection of applications that are completely independent and self-contained; thus, the interested reader can choose any chapter and skip to another without losing continuity.
Download or read book MIMO System Technology for Wireless Communications written by George Tsoulos and published by CRC Press. This book was released on 2018-10-03 with total page 400 pages. Available in PDF, EPUB and Kindle. Book excerpt: For broadband communications, it was frequency division multiplexing. For optical communications, it was wavelength division multiplexing. Then, for all types of networks it was code division. Breakthroughs in transmission speed were made possible by these developments, heralding next-generation networks of increasing capability in each case. The basic idea is the same: more channels equals higher throughput. For wireless communications, it is space-time coding using multiple-input-multiple-output (MIMO) technology. Providing a complete treatment of MIMO under a single cover, MIMO System Technology for Wireless Communications assembles coverage on all aspects of MIMO technology along with up-to-date information on key related issues. Contributors from leading academic and industrial institutions around the world share their expertise and lend the book a global perspective. They lead you gradually from basic to more advanced concepts, from propagation modeling and performance analysis to space-time codes, various systems, implementation options and limitations, practical system development considerations, field trials, and network planning issues. Linking theoretical analysis to practical issues, the book does not limit itself to any specific standardization or research/industrial initiatives. MIMO is the catalyst for the next revolution in wireless systems, and MIMO System Technology for Wireless Communications lays a thorough and complete foundation on which to build the next and future generations of wireless networks.
Download or read book Channel Estimation in TDD and FDD Based Massive MIMO Systems written by Javad Mirzaei and published by . This book was released on 2021 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: There are three parts to this thesis. In the first part, we study the channel estimation problem in frequency-selective multi-user (MU) multi-cell massive multiple-input multiple-output (MIMO) systems, where, a time-domain semi-blind channel estimation technique is proposed. Compared to frequency-domain, the time-domain channel estimation requires fewer parameters be estimated. Importantly, the time-domain estimation has enough samples for an accurate channel estimate. Given this many samples in the time-domain, the proposed channel estimation technique obtains a better estimate of the channel. Here, there is no assumption on orthogonality of users' channels, knowledge of large-scale fading coefficients, and the orthogonality between the training symbols of the users in all cells. The second part of the thesis studies the channel estimation problem in correlated massive MIMO systems with a reduced number of radio-frequency (RF) chains. Leveraging the knowledge of channel correlation matrices, we propose to estimate the channel entries in its eigen-domain. Due to the limited number of RF chains, channel estimation is typically performed in multiple time slots. Using the minimum mean squared error (MMSE) criterion, the optimal precoder and combiner in each time slot are aligned to transmitter and receiver eigen-directions, respectively. Meanwhile, the optimal power allocation for each training time slots is obtained via a waterfilling-type expression. In the final part, we study the downlink channel estimation for frequency-division-duplex (FDD) massive MIMO systems. Acquiring downlink channel state information in these systems is challenging due to the large training and feedback overhead. Motivated by the partial reciprocity of uplink and downlink channels, we first estimate the frequency-independent channel parameters, i.e., the path gains, delays, angles-of-arrivals (AoAs) and angles-of-departures (AoDs), via uplink training, since these parameters are common in both uplink and downlink. Then, the frequency-specific channel parameters are estimated via downlink training using a very short training signal. To efficiently estimate the channel parameters in the uplink, the underlying distribution of the channel parameters is incorporated as a prior into our estimation algorithm. This distribution is captured using deep generative models (DGMs). The proposed channel estimation technique significantly outperforms the conventional channel estimation techniques in practical ranges of signal-to-noise ratio (SNR).
Download or read book Practical Guide to MIMO Radio Channel written by Tim Brown and published by John Wiley & Sons. This book was released on 2012-02-16 with total page 233 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides an excellent reference to the MIMO radio channel In this book, the authors introduce the concept of the Multiple Input Multiple Output (MIMO) radio channel, which is an intelligent communication method based upon using multiple antennas. Moreover, the authors provide a summary of the current channel modeling approaches used by industry, academia, and standardisation bodies. Furthermore, the book is structured to allow the reader to easily progress through the chapters in order to gain an understanding of the fundamental and mathematical principles behind MIMO. It also provides examples (i.e. Kroenecker model, Weicheselberger model, geometric and deterministic models, and ray tracing), system scenarios, trade-offs, and visual explanations. The authors explain and demonstrate the use and application of these models at system level. Key Features: Provides a summary of the current channel modeling approaches used by industry, academia and standardisation bodies Contains experimental and measurement based results Provides a comprehensive down to earth approach with concise and visual explanations of MIMO Radio Channel Covers a variety of system scenarios and explains the trade-offs involved in each Accompanying website containing MATLAB code and solutions to related problems http://www.tim.brown76.name/MIMObook) Practical Guide to the MIMO Radio Channel with MATLAB examples is an invaluable reference for R&D engineers and professionals in industry requiring familiarisation with the concept, and engineers entering the field or working in related fields seeking an introduction to the topic. Postgraduate and graduate students will also find this book of interest.
Download or read book Cooperative Communications and Networking written by K. J. Ray Liu and published by Cambridge University Press. This book was released on 2009 with total page 643 pages. Available in PDF, EPUB and Kindle. Book excerpt: Presents the fundamentals of cooperative communications and networking with a holistic approach to principal topics where improvements can be obtained.
Download or read book Massive MIMO Systems written by Kazuki Maruta and published by MDPI. This book was released on 2020-07-03 with total page 330 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple-input, multiple-output (MIMO), which transmits multiple data streams via multiple antenna elements, is one of the most attractive technologies in the wireless communication field. Its extension, called ‘massive MIMO’ or ‘large-scale MIMO’, in which base station has over one hundred of the antenna elements, is now seen as a promising candidate to realize 5G and beyond, as well as 6G mobile communications. It has been the first decade since its fundamental concept emerged. This Special Issue consists of 19 papers and each of them focuses on a popular topic related to massive MIMO systems, e.g. analog/digital hybrid signal processing, antenna fabrication, and machine learning incorporation. These achievements could boost its realization and deepen the academic and industrial knowledge of this field.
Download or read book Towards Increasing the Capacity in MIMO Wireless Communication Systems written by Seyed Alireza Banani and published by . This book was released on 2011 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The use of multiple antennas on both sides of a multipath channel can improve the capacity without additional transmit power. It is possible, in principle, for the capacity to increase linearly with the number of antennas even when the channel state information (CSI) is unknown at the transmitter. These known capacity results require many assumptions, including the need for the CSI to be known perfectly. In practice, perfect CSI is never known perfectly a priori, and its estimation, without using an ideal blind technique (none are available), requires bandwidth resource which reduces the capacity. Moreover, various factors such as digital modulation, finite block lengths, and imperfect power allocation degrade the capacity from the Shannon limit to the practicable possibilities of a digital link. These practical impairments motivate new techniques for increasing the capacity in MIMO systems, and in this thesis, two sets of techniques are presented. The first set includes two new decision-directed techniques for estimating the channel matrix, and they are shown to have higher capacity compared to pilot symbol assisted modulation systems since no pilots are required. These techniques are applicable for various open-loop SISO/MIMO wireless communications systems including systems employing OFDM, nonlinear/linear equalization, MRC, Alamouti coding, and spatial multiplexing. In the second set, the eigen-MIMO capacity is maximized in the presence of different practical impairments. In particular, the joint influence of training-based channel estimation and imperfect feedback on both the information-theoretic and the practicable water-filled eigen-MIMO capacities, are analyzed. Water-filled eigenchannels maximize the information theoretic capacity, but for implementation, the required adaptive modulation means high complexity. One simplification is to have fixed modulation over a fixed number of eigenchannels. However, the error rate deteriorates with the weakest eigenchannel and to counter this while maintaining high throughput, the information rate is maximized with an output SNR constraint. On the other hand, if higher complexity can be tolerated, adaptive modulation and coding can be deployed for high throughput. In this context, a high capacity eigen-MIMO system using Reed-Solomon coded M-QAM is developed. This includes an appropriate QAM, code rate, and power allocation for each eigenchannel.
Download or read book Capacity Analysis of Asymptotically Large MIMO Channels written by Georgy Levin and published by . This book was released on 2008 with total page 304 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Analysis and Design of Networked Control Systems written by Keyou You and published by Springer. This book was released on 2015-01-03 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt: This monograph focuses on characterizing the stability and performance consequences of inserting limited-capacity communication networks within a control loop. The text shows how integration of the ideas of control and estimation with those of communication and information theory can be used to provide important insights concerning several fundamental problems such as: · minimum data rate for stabilization of linear systems over noisy channels; · minimum network requirement for stabilization of linear systems over fading channels; and · stability of Kalman filtering with intermittent observations. A fundamental link is revealed between the topological entropy of linear dynamical systems and the capacities of communication channels. The design of a logarithmic quantizer for the stabilization of linear systems under various network environments is also extensively discussed and solutions to many problems of Kalman filtering with intermittent observations are demonstrated. Analysis and Design of Networked Control Systems will interest control theorists and engineers working with networked systems and may also be used as a resource for graduate students with backgrounds in applied mathematics, communications or control who are studying such 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 2008-07-24 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt: The emerging wireless communication systems, such as cellular communications systems and wireless net-works, are changing the life style nowadays dramatically. The prospect of modern wireless communication systems is very attractive by declaring the ability of ubiquitous access to information with high-quality and high-speed service. The Orthogonal Frequency Division Multiplexing (OFDM) technique is one promising candidate for the $4^{th}$ generation wireless systems, due to its merits of high flexibility and low equalization complexity for wideband wireless communication applications. To further enhance the communication system capacity and reliability, multiple antenna techniques can be integrated into OFDM systems. As a preliminary step, the physical characteristics of wideband radio channels and the channel modeling issue are addressed. The channel capacity with multiple antennas is presented by considering both cases of ideal and practical estimated channel state information (CSI) in the system. The fundamentals of the OFDM transmission technique are introduced. With the OFDM transmission structu-re the frequency-selective wideband radio channel is decomposed into a set of parallel subcarriers, and each subcarrier can be treated as a flat-fading narrowband channel. Several Multiple-Input-Multiple-Output (MIMO) technologies are discussed, in the scope of subcarrier-based MIMO encoding and decoding within the MIMO-OFDM transceiver structure, i.\ e.\ integrate the MIMO signal processing algorithms into a wideband OFDM system, where each OFDM subcarrier is regarded individually as a narrowband flat-fading subsystem with the Discrete Fourier Transform (DFT) and Inverse Discrete Fou-rier Transform (IDFT). The simulation results and analysis are presented under various radio channel condi-tions with ideal CSI. For practical reasons, channel estimation is necessary for coherent-detection MIMO-OFDM systems. The Pilot-based Channel Estimation (PBCE) schemes are implemented to evaluate the system performance with the realistically estimated CSI. With estimated CSI for MIMO encoding/decoding and data symbol detection, the system performance is reasonably degraded. The system performance results with estimated CSI are presented, and the impact of channel estimation errors is analyzed. In order to ensure a reliable and flexible data transmission in MIMO-OFDM systems, the indicator-based link adaptation procedure is employed to optimize the system throughput by selecting a proper Transmission Mode (TM) according to the instantaneous channel conditions. The Transmission Mode Selection (TMS) procedure with two-dimensional (2D) indicators is developed. A set of indicator candidates and their appro-ximation functions are proposed. With the indicator simulation results and the proposed TMS procedure for MIMO-OFDM systems, the average system throughput results are illustrated for both the conventional link adaptation method and the proposed 2D indicator-based TMS approach. Finally, the general system performance results of MIMO-OFDM systems are summarized. Arguments and suggestions are further made on how to design a MIMO-OFDM system in various wideband wireless com-munication applications.
