Download or read book Channel Estimation in Wireless Communication Systems Employing Multiple Antennas written by Mikael Coldrey and published by . This book was released on 2004 with total page 94 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Introduction to MIMO Communications written by Jerry R. Hampton and published by Cambridge University Press. This book was released on 2014 with total page 303 pages. Available in PDF, EPUB and Kindle. Book excerpt: This accessible guide contains everything you need to get up to speed on the theory and implementation of MIMO techniques.

Download or read book Bandwidth Efficient Channel Estimation for Multiple input Multiple output MIMO Wireless Communication Systems A Study of Semi blind and Superimposed Schemes written by Aditya K. Jagannatham and published by . This book was released on 2007 with total page 202 pages. Available in PDF, EPUB and Kindle. Book excerpt: Superimposed pilots (SP) are another interesting alternative to reduce the impact of a pilot overhead without a significant increase in computational complexity. We present a study of the mean-squared error (MSE) and throughput performance of superimposed pilots (SP) for the estimation of a MIMO wireless channel. We illustrate a semi-blind scheme for SP based MIMO channel estimation, which improves performance over the traditional mean-estimator. A new result is presented for the worst-case capacity of a communication channel with correlated information symbols and noise. We also address the issue of optimal source-pilot power allocation for SP. In the end we consider the problem of estimation of a time-selective MIMO wireless channel using superimposed pilot (SP) symbols. We demonstrate a scheme for channel estimation based on a complex exponential basis expansion model (CEBEM) approximation of the time-selective wireless channel. We further reduce the MSE of estimation by employing an expectation-maximization (EM) based iterative estimation procedure.

Download or read book Wireless Multi Antenna Channels written by Serguei Primak and published by John Wiley & Sons. This book was released on 2011-10-14 with total page 250 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book offers a practical guide on how to use and apply channel models for system evaluation In this book, the authors focus on modeling and simulation of multiple antennas channels, including multiple input multiple output (MIMO) communication channels, and the impact of such models on channel estimation and system performance. Both narrowband and wideband models are addressed. Furthermore, the book covers topics related to modeling of MIMO channel, their numerical simulation, estimation and prediction, as well as applications to receive diversity, capacity and space-time coding techniques. Key Features: Contains significant background material, as well as novel research coverage, which make the book suitable for both graduate students and researchers Addresses issues such as key-hole, correlated and non i.i.d. channels in the frame of the Generalized Gaussian approach Provides a unique treatment of generalized Gaussian channels and orthogonal channel representation Reviews different interpretations of scattering environment, including geometrical models Focuses on the analytical techniques which give a good insight into the design of systems on higher levels Describes a number of numerical simulators demonstrating the practical use of this material. Includes an accompanying website containing additional materials and practical examples for self-study This book will be of interest to researchers, engineers, lecturers, and graduate students.

Download or read book Channel Modeling and Direction of arrival Estimation in Mobile Mutiple antenna Communication Systems written by Arastoo Rostami Ravari and published by . This book was released on 2005 with total page 346 pages. Available in PDF, EPUB and Kindle. Book excerpt: Antennas that are able to adaptively direct the transmitted (and received) energy are of great interest in future wireless communication systems. The directivity implies reduced transmit power and interference, and also a potential for increased capacity. This thesis treats some modeling and estimation problems in mobile communication systems that employ multiple antennas, primarily at the base stations. With multiple antennas at the receive side, the spatial dimensions is added, and processing is performed in both the temporal and spatial domains. The potential benefits are increased range, fading diversity and spatially selective transmission. Specifically, the problems dealt in this thesis are mainly related to the uplink transmission from mobile to the base station. Two main topics are studied modeling and estimation of channel parameters. This thesis first describes the modeling of the reflected power distibution due to the scatterers close to the mobile station, in terms of the received signal azimuth at the base station with multiple-antenna. As a more realistic modeling, a multipath fading deterministic channel model is proposed to generated properly correlated faded waveforms with appropriate power distibution through azimuth spread of received signal. The purpose of the proposed channel model is to model fading received signal waveforms with Laplacian distribution of power through received signal azimuth. This thesis is divided into two parts; in the first part multipath fading by local scattering are used to derive a channel model including the spatial dimension for non frequency-selective fading. This means that the mobile is not modeled as a point source but as a cluster of a large number independent scatterers with small time delay spread to take into account angular spreading of the signal. Properly correlated fading waveforms are obtained by taking into account the angular spread of the scattered signals from a particular distribution of scatterers. By appropriate scaling of the array response vector (ARV) based non-equal locations for various received signal components as a functionc of distance from the transmitter, the reflected power a given scatterer in no longer constant but varies as a function of the distance from the transmitter. Our proposed channel model is able to produce fading signal waveform which agrees with the results of reflected angular power dispersion measured in the field, e.g. Laplacian distribution of power in azimuth. It is also shown that the channel response can be modeled as a complex Gaussian vector. Although the channel will be frequency selective in the case of multipath propagation with considerable time spread, this can be modeled as having more than one cluster of scatterers. By employing Walsh-Hadamard codewords an extension to wideband multipath fading model is achieved. It is shown that the statisctical properties of proposed model such as signal waveform's correlation, autocorrelation and crosscorrelation between generated paths, are in good agreement with the theory in space and time domain. The model can be applied to evaluate smart antenna systems and beamforming algorithms in the uplink by generating uncorrelated multipaths Rayleigh fading waveforms with certain spatio-temporal correlation and spatial coordinates relative to base stations to simulate received signals from mobiles and interferers. Bit-error-rate (BER) performance analysis of uniform linear array antenna (ULA) based on correlation matrix is also presented as an application of our proposed model for multiple-antenna evaluations. Our simulated results show 5% improvement than other published related works. One problem when modeling frequency selective fading is that each cluster has to be assigned spatial parameters. Since the joint spatial and temporal characteristics are unknown, non-parametric channel estimation approaches are required in this case in order to estimate the channel parameter, which is the subject of the second part. The second part of the thesis deals with channel parameter estimation of distributed scattering sources. Because of local scattering around the transmitter the signal waveforms appears spatially distributed at the receiver. The characterization of the spatial channel, in particular mean direction of arrival and spatial spread, is of prime interest for system optimization and performance prediction. Low-complexity spectral-based estimators are used for the estimation of direction and spatial spread of the distributed source by employing the proposed channel model for simulation. Estimated parameters from recent measurements ([PMF00]) are compared with estimated parameters from model generated waveforms as well as theoretical distribution of receiving signal's angular speed. Good agreement between them is observed which shows the correctness of our proposed channel model for simulating spatio-temporally correlated received signal at an antenna array. The estimated parameters error improved by 5% over the other published related works.

Download or read book Channel Estimation and Receiver Design for Wireless Communications Employing Multiple Antennas written by and published by . This book was released on 2004 with total page 326 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Performance of Multi antenna Wireless Systems with Channel Estimation Error written by Nadia Jamal and published by . This book was released on 2015 with total page 115 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless services and applications have become extremely popular and widely employed over the past decades. This, in turn, has led to a dramatic increase in the number of wireless users who demand reliable services with high data rates. But such services are very challenging to provide due to radio channel impairments including multipath fading and co-channel interference. In this regard, the use of multiple antennas in wireless systems was proposed recently which has rapidly received great attention. Multi-antenna technology is shown to have powerful capabilities to improve reliability via spatial diversity and to increase data rates via spatial multiplexing as compared with traditional single-antenna systems. Furthermore, by exploiting additional spatial dimensions, transmit beamforming techniques can be used to manage co-channel interference in such systems. In a rich scattering environment, multiple antennas that are located sufficiently far apart at a transmitter experience independent fading with high probability. Therefore, the transmitter can send redundant versions of the same data stream over these independent channels to improve reliability. In particular, if the transmitter has access to perfect channel state information (CSI), it can set the beamforming weights such that the received signals from different transmit antennas combine constructively at some intended receiver(s) and destructively at some unintended receiver(s) so that no co-channel interference is generated. Spatial multiplexing is another powerful multi-antenna transmission technique which aids in enhancing data rates without increasing bandwidth or transmit power. Multiple parallel and independent channels can be established between a transmitter and a receiver that both use multiple antennas in a rich scattering environment. Therefore, multiple independent streams of data can be simultaneously sent over these channels within the bandwidth of operation. This, in turn, enhances the data rate by a multiplicative factor equal to the number of the independent streams. Water-filling is a strategy that achieves the maximum data rate in such multiple-input multiple-output (MIMO) systems when perfect CSI is available at both the transmitter and the receiver. In practice, CSI can be obtained at the receiver by the use of training sequences and its accuracy can be increased by carefully selecting sequences with good auto-correlation properties. The transmitter can acquire CSI by using the channel reciprocity principle in wireless systems or by relying on a feedback path to convey the CSI from the receiver. Due to practical limitations such as rate-limited feedback links and the delay involved in such procedures, perfect CSI can be very challenging to obtain at the transmitter side. This motivates the need to evaluate the effect of imperfect CSI at the transmitter (CSIT) on the performance of transmit diversity and beamforming in multiple-input single-output (MISO) systems and water-filling power allocation in MIMO systems. In this thesis, transmit diversity and beamforming are studied in a MISO system with an n-antenna transmitter, an intended single-antenna receiver, and some unintended single- antenna receivers. Two scenarios are considered, namely, null-steering beamforming and [epsilon]-threshold beamforming in which the allowable interference threshold at the unintended receivers is zero and [epsilon] > 0, respectively. With perfect CSIT, null-steering beamforming can successfully nullify interference at m unintended receivers, where m

Download or read book Next Generation Wireless Communications Using Radio over Fiber written by Nathan J. Gomes and published by John Wiley & Sons. This book was released on 2012-08-15 with total page 315 pages. Available in PDF, EPUB and Kindle. Book excerpt: Taking a coherent and logical approach, this book describes the potential use of co-ordinated multipoint systems supported by radio over fiber. It covers an impressive breadth of topics, ranging from components, subsystem and system architecture, to network management and business perspectives. The authors show the importance of radio over fiber in eliminating or mitigating against the current, perceived barriers to the use of co-ordinated multipoint, and the drivers for standardisation activities in future mobile/wireless systems over the next few years. The book brings together the system concept for centralized processing, including what is required for co-existence with legacy wireless systems, the algorithms that can be used for improving wireless bandwidth utilization at physical and MAC layers and the radio over fiber network and link design necessary to support the wireless system. Other important research is also covered as the authors look at compensating for radio over fiber impairments and providing simple network management functions. A study of service provision and the business case for such a future wireless system is also fully considered. This book comes at an important time for future wireless systems with standardization of fourth generation wireless systems still ongoing. The content enables readers to make key decisions about future standardisation and their own research work. The business analysis also makes the book useful to those involved in deciding the future directions of telecoms organisations. This information will be core to their decision-making as it provides technical knowledge of the state-of-the-art but also system level assessments of what is possible in a business environment.

Download or read book Advanced MIMO Systems written by Prof. Kosai Raoof and published by Scientific Research Publishing, Inc. USA. This book was released on 2009-09 with total page 17 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book is written for graduate students and professionals concerned with MIMO systems. It reviews mostknown multiple antenna techniques for single-use point-to-point systems, from how multiple antennas help provide diversity and multiplexing to the detection techniques for these systems. This book covers the main fields of MIMO systems with 10 chapters; each chapter covers either base-bandsignal processing aspect or application.

Download or read book Spatial Interference Cancellation and Channel Estimation for Multiple input Multiple output Wireless Communication Systems written by Chaiyod Pirak and published by . This book was released on 2005 with total page 276 pages. Available in PDF, EPUB and Kindle. Book excerpt: A multiple-input multiple-output (MIMO) wireless communication system is one of prominent systems for realizing high data-rate transmission services highly demanded in the future wireless communications. It can provide a significant performance enhancement to the wireless communications, including increased data rates through a multiplexing gain, an enhanced error probability through a diversity gain, and cancellation of multiple access interference through smart antennas. However, for such system employing coherent receivers, an accurate channel state information is crucially needed. These performance advantages and challenge, respectively, are the motivations of this dissertation. In the first part of this dissertation, a novel smart antenna system for interference canceling receivers in direct-sequence code-division multiple access (DS-CDMA) systems is proposed. This proposed scheme only exploits the spreading codes of users as the information forits weight adjustment for controlling its beam. This proposed scheme is also robust to the in-beam interference, especially in the near-far effect situation. Convergence and error probability performance analysis is also carried out. Theoretical and simulation results indicate that the proposed scheme outperforms the existing works.

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.

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 and Feedback for Multiple Antenna Communication written by Chandra Ramabhadra Murthy and published by . This book was released on 2006 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation studies several aspects of feedback-based communication with multiple antennas, such as the estimation of the Channel State Information (CSI), the quantization of the CSI with a finite number of bits to enable its feedback to the transmitter, as well as the effect of errors in the feedback channel on the performance of the communication system. Channel estimation is doubly important in feedback-based communication because inaccurate CSI affects not only the receiver performance, but also results in sub-optimal transmission. In this context, Multiple Input Multiple Output (MIMO) flat-fading channel estimation when the transmitter employs Maximum Ratio Transmission (MRT) is studied. Two competing schemes for estimating the transmit and receive beamforming vectors of the channel matrix are analyzed: a training based conventional least squares estimation (CLSE) scheme and a closed-form semi-blind (CFSB) scheme that employs training followed by information-bearing spectrally white data symbols. Employing matrix perturbation theory, expressions for the mean squared error (MSE) in the beamforming vector, the average received SNR and the symbol error rate (SER) performance of both the semi-blind and the conventional schemes are derived. Another important issue in beamforming-based communication with multiple antennas is the feedback of CSI. Hence, the design and analysis of quantizers for Equal Gain Transmission (EGT) systems with finite rate feedback-based communication in flat-fading Multiple Input Single Output (MISO) systems is considered. Two popular approaches for quantizing the phase angles are contrasted: vector quantization (VQ) and scalar quantization (SQ). Closed-form expressions are derived for the performance of quantized feedback in terms of capacity loss and outage probability in the case of i.i.d. Rayleigh flat-fading channels. In the work described above, the feedback channel is assumed to be free of delay and noise. With the view to understand the effect of errors on quantization, this dissertation considers the more general problem of characterizing the high-rate performance of source coding for noisy discrete symmetric channels with random index assignment. Theoretical expressions for the performance of source coding for noisy channels are derived for a large class of distortion measures. The theoretical expressions are used to derive new results for two specific applications. The first is the quantization of the CSI for MISO systems with beamforming at the transmitter. The second application is in the wideband speech compression problem, i.e., that of quantizing the linear predictive coding parameters in speech coding systems with the log spectral distortion as performance metric.

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 Wireless Channel Estimation and Channel Prediction for MIMO Communication Systems written by Farnoosh Talaei and published by . This book was released on 2017 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: In this dissertation, channel estimation and channel prediction are studied for wireless communication systems. Wireless communication for time-variant channels becomes more important by the fast development of intelligent transportation systems which motivates us to propose a reduced rank channel estimator for time-variant frequency-selective high-speed railway (HSR) systems and a reduced rank channel predictor for fast time-variant flat fading channels. Moreover, the potential availability of large bandwidth channels at mm-wave frequencies and the small wavelength of the mm-waves, offer the mm-wave massive multiple-input multiple-output (MIMO) communication as a promising technology for 5G cellular networks. The high fabrication cost and power consumption of the radio frequency (RF) units at mm-wave frequencies motivates us to propose a low-power hybrid channel estimator for mm-wave MIMO orthogonal frequency-division multiplexing (OFDM) systems. The work on HSR channel estimation takes advantage of the channel's restriction to low dimensional subspaces due to the time, frequency and spatial correlation of the channel and presents a low complexity linear minimum mean square error (LMMSE) estimator for MIMO-OFDM HSR channels. The channel estimator utilizes a four-dimensional (4D) basis expansion channel model obtained from band-limited generalized discrete prolate spheroidal (GDPS) sequences. Exploiting the channel's band-limitation property, the proposed channel estimator outperforms the conventional interpolation based least square (LS) and MMSE estimators in terms of estimation accuracy and computational complexity, respectively. Simulation results demonstrate the robust performance of the proposed estimator for different delay, Doppler and angular spreads. Channel state information (CSI) is required at the transmitter for improving the performance gain of the spatial multiplexing MIMO systems through linear precoding. In order to avoid the high data rate feedback lines, which are required in fast time-variant channels for updating the transmitter with the rapidly changing CSI, a subframe-wise channel tracking scheme is presented. The proposed channel predictor is based on an assumed DPS basis expansion model (DPS-BEM) for exploiting the variation of the channel coefficients inside each sub-frame and an autoregressive (AR) model of the basis coefficients over each transmitted frame. The proposed predictor properly exploits the channel's restriction to low dimensional subspaces for reducing the prediction error and the computational complexity. Simulation results demonstrate that the proposed channel predictor out-performs the DPS based minimum energy (ME) predictor for different ranges of normalized Doppler frequencies and has better performance than the conventional Wiener predictor for slower time-variant channels and almost the similar performance to it for very fast time-variant channels with the reduced amount of computational complexity. The work on the hybrid mm-wave channel estimator considers the sparse nature of the mm-wave channel in angular domain and leverages the compressed sensing (CS) tools for recovering the angular support of the MIMO-OFDM mm-wave channel. The angular channel is treated in a continuous framework which resolves the limited angular resolution of the discrete sparse channel models used in the previous CS based channel estimators. The power leakage problem is also addressed by modeling the continuous angular channel as a multi-band signal with the bandwidth of each sub-band being proportional to the amount of power leakage. The RF combiner is designed to be implemented using a network of low-power switches for antenna subset selection based on a multi-coset sampling pattern. Simulation results validate the effectiveness of the proposed hybrid channel estimator both in terms of the estimation accuracy and the RF power consumption.

Download or read book Wireless Communication Systems written by Xiaodong Wang and published by Prentice Hall Professional. This book was released on 2004 with total page 716 pages. Available in PDF, EPUB and Kindle. Book excerpt: Wireless Communication Systems: Advanced Techniques for Signal Receptionoffers a unified frameworkfor understanding today's newest techniques for signal processing in communication systems - andusing them to design receivers for emerging wireless systems. Two leading researchers cover a fullrange of physical-layer issues, including multipath, dispersion, interference, dynamism, andmultiple-antenna systems. Topics include blind, group-blind, space-time, and turbo multiuserdetection; narrowband interference suppression; Monte Carlo Bayesian signal processing; fast fadingchannels; advanced signal processing in coded OFDM systems, and more.

Download or read book Transmit Beamforming for Multiple Antenna Systems with Imperfect Feedback written by Yogananda R. Isukapalli and published by . This book was released on 2009 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: Multiple antennas can effectively minimize the negative impact of multiplicative fading in wireless communication systems by providing spatial diversity. In this thesis we consider a spatial diversity scheme with multiple antennas at the base station. In order to achieve the optimum performance gains, i.e., to achieve both the array gain and the diversity gain, the transmitter needs to know channel information. In frequency division duplexing systems the channel information has to be fed back to the transmitter. This feedback requirement leads to various forms of imperfection. A typical practical system has three main sources of feedback imperfection, namely, channel estimation errors, channel quantization, and feedback delay. In this thesis we comprehensively study the impact of feedback imperfections on the performance of multi-antenna systems. We develop a general framework capturing the three forms of feedback imperfection, i.e., estimation errors, quantization, and delay, for both spatially independent and correlated fading scenarios. In the modeling of imperfect feedback, we show that depending on the beamforming vector construction, the feedback delay error term can be known or unknown at the receiver. On the other hand, channel estimation error term is always unknown at the receiver. In a slow fading context, i.e., in scenarios where channel remains constant for the entire packet, we highlight the fact that both the estimation error term and the delay error term remain constant, with estimation error term unknown at the receiver and delay error term known at the receiver, for the entire packet while the thermal noise changes from symbol-to-symbol. For spatially independent channels, with the help of general framework, we then analytically quantify the effect of the three forms of feedback imperfection on the symbol and bit error probabilities of both M-PSK and M-ary rectangular QAM constellations with Gray code mapping. We also derive an analytical expression for the average packet error probability with BPSK signaling. In addition, with channel estimation errors and feedback delay, for spatially correlated channels, we develop codebook design algorithms specific to the modulation format and ergodic capacity. The new optimum codebooks show an improvement in performance compared to the existing set of codebooks available in the literature. Utilizing high resolution quantization theory and assuming perfect channel estimation at the receiver, we analyze the loss in average symbol error probability for spatially independent and correlated finite-rate feedback transmit beamforming multiple input single output systems with M1xM2-QAM constellation. We also address the issue of minimizing the negative impact of feedback delay. A natural way to combat the effect of feedback delay is channel prediction. We study the role of ergodicity in wireless channel modeling and provide an insight into when statistical channel models that employ ensemble averaging are appropriate for the purpose of channel prediction. Simulation results complement the extensive set of analytical expressions derived in the thesis.