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 Channel State Information Reduction in Frequency and Time Domains for Closed loop MIMO OFDM Systems written by 陳仁賢 and published by . This book was released on 2009 with total page 44 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Signal Processing Channel Estimation and Link Adaptation in MIMO OFDM Systems written by Jianjun Ran and published by Cuvillier Verlag. This book was released on 2008 with total page 161 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Turbo Processing for Closed loop MIMO Systems with Limited Feedback written by Yi Yu and published by . This book was released on 2007 with total page 139 pages. Available in PDF, EPUB and Kindle. Book excerpt: In order to satisfy the huge demand for high data rates and improved link quality wireless communication systems, new techniques are required, which can exploit the limited resources: bandwidth and power. MIMO wireless technology employing multiple antennas at the transmitter and/or at the receiver is an efficient solution for next generation communication systems because it can produce potential capacity gains over SISO systems using the same bandwidth and transmit power. In order to approach the capacity of MIMO systems, space-time block code (STBC) is one of space-time coding strategies that improves transmission reliability by means of transmit diversity. It has been demonstrated that the complex full-rate, orthogonal STBC, offering full diversity, is only limited to the case of two transmit antennas. For more than two transmit antennas, various non-orthogonal STBCs have been proposed to achieve a high rate at the expense of loosing diversity gains and increasing the decoding complexity. This work presented focus on designing limited feedback schemes for four transmit-antenna NO-STBC to achieve more diversity gains. Assuming that only partial channel state information is available at the transmitter, two types of closed-loop NO-STBCs using two feedback bits are studied under different channel conditions: closed-loop quasi-orthogonal STBC and closed-loop extended-orthogonal STBC. Moreover, low-complexity Turbo receivers are respectively designed for these two CL-NO-STBCs in BICM systems. Simulation results show that with iterative processing between the MIMO decoder and the channel decoder, significant coding gains can be achieved.

Download or read book Performance of Analog Feedback in Closed loop Transmit Diversity Systems written by Eddy Chiu and published by . This book was released on 2006 with total page 170 pages. Available in PDF, EPUB and Kindle. Book excerpt: Knowledge of channel state information (CSI) at the transmitter can be used for transmit beamforming. However, providing the transmitter with CSI typically requires feedback from the receiver, and this is complicated by low feedback rates. This thesis is concerned with the efficient transmission of CSI in the uplink, and data in the downlink, of a closed-loop transmit diversity system. Two main ideas are explored. First, we consider the employment of analog CSI feedback whereby downlink gain estimates are fed back periodically to the base station at a rate of only one analog symbol per estimate per data frame. Second, we consider the use of position dependent modulation (PDM) to counter the signal to noise ratio variation across a downlink data frame. Simulation results indicated that analog feedback can achieve better bit error rate (BER) than digital feedback, and PDM can attain higher throughput than fixed modulation at a target BER.

Download or read book Performance of Hybrid and Pure Analog CSI Feedback in MIMO Systems with Time selective Fading written by Phoenix Yuan and published by . This book was released on 2010 with total page 176 pages. Available in PDF, EPUB and Kindle. Book excerpt: In a Frequency division duplex (FDD) system, knowledge of channel state information (CSI) at the transmitter requires a closed feedback loop. In this thesis, we examine system performance associated with different types of feedback operating in time-selective Rayleigh fading channels. For a singleuser system with multiple transmit antennas, we consider hybrid analog/digital feedback, which is an extension for the traditional digital-only codebook feedback. An extra analog symbol that encapsulates channel's amplitude and phase information that is otherwise lost in the codebook quantization process is fed back for channel tracking purpose. For a multiuser multiple-input-multipleoutput (MIMO) system, we consider the deployment of pure analog CSI feedback. A modified minimum mean square error (MMSE) criterion is used to incorporate downlink channel prediction into the precoder design and user selection process. In both cases, the proposed types of CSI feedback can achieve better BER in comparison to digital CSI feedback.

Download or read book Channel State Information in Multiple Antenna Systems written by Jingnong Yang and published by . This book was released on 2006 with total page 109 pages. Available in PDF, EPUB and Kindle. Book excerpt: Most previous papers on CSI feedback did not consider uncertainties in the feedback process, such as unexpected delay or error in the feedback channel. Such uncertainties exist in reality and ignoring them results in suboptimal algorithms. We consider channel mean-feedback with an unknown delay and propose a broadcast approach that is able to adapt to the quality of the feedback.

Download or read book Channel Feedback Techniques for Adaptive Mimo Ofdm Systems written by Muhammad Rehan Khalid and published by LAP Lambert Academic Publishing. This book was released on 2012-04 with total page 108 pages. Available in PDF, EPUB and Kindle. Book excerpt: The new generation of wireless devices support higher data rates. Most of the new standards like HSPA utilize the spatial multiplexing of MIMO channels to achieve higher data rates, and exploit the diversity of MIMO channels to provide better performance. Hence there is an increased interest in the analysis of MIMO communication systems. The eventual objective is to achieve higher data rates in MIMO systems under the constraints of limited bandwidth and power. The radio spectrum is a scarce resource, and very expensive to license. Hence improved and efficient channel utilization techniques are requisite, that exploit the radio spectrum more proficiently. The multipath characteristics of the environment cause the MIMO channels to be frequency selective. For frequency selective deep fading, MIMO system remains ineffective. OFDM, a multicarrier transmission scheme, is well recognized for its potential for attaining high rate transmission over frequency selective channels. It can transform such a frequency selective MIMO channel into a set of parallel frequency-flat channels. Implementing space resources based on OFDM i.e., MIMO-OFDM provides higher data rate.

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 CSI Reduction for Close loop MIMO OFDM Systems by Parameterization written by 謝國旺 and published by . This book was released on 2008 with total page 45 pages. Available in PDF, EPUB and Kindle. Book excerpt:

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 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 Doppler Shift Estimation of MIMO OFDM Systems Based on Auto correlation Function of Channel Estimate written by Qin Zhu 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 (MIMO) and orthogonal frequency division multiplexing (OFDM) techniques have been considered as a strong candidate for the next-generation - wireless communication systems, due to their well-known advantages in high data-rate wireless transmission as well as high frequency spectrum efficiency. In the mean time, channel state information (CSI) is required for precise detection and recovery of signals. Therefore, channel estimation plays a significant role in MIMO-OFDM systems. On the other hand, due to the high mobility of wireless terminals, Doppler shift (DS) can be one of the major side-effects of utilizing MIMO-OFDM techniques, which may lead to severe performance loss. Many schemes on DS estimation have been developed for broadband single-input single-output (SISO) systems. A commonly used method is to exploit the auto-correlation property of the channel impulse response (CIR) estimated by well-developed channel estimation approaches, which not only has high accuracy but also moderate computational complexity. Hence, we first investigate an efficient channel estimation method in this thesis. We will then focus on Jakes' model based DS estimation schemes, and further extend to independently identically distributed (i.i.d.) MIMO-OFDM fading channels with both Rayleigh and Rician distributions. In the first part of the thesis, a training-sequence (TS) based least square (LS) channel estimation scheme is presented for MIMO-OFDM systems along with plenty of computer simulations and corresponding analyses. Experimental study shows that the CIR estimates obtained by the LS method are reliable under moderate channel conditions, and can efficiently be utilized for DS estimation. The second part of the thesis first studies the auto-correlation function (ACF) based DS estimation schemes for SISO-OFOM systems in Rayleigh fading channels, and then extends it to Rician fading channels by developing a new approach along with the analysis of its accuracy and complexity. Thereafter, we apply those approaches to MIMO-OFOM systems and present a few enhanced methods by using non-linear interpolation under certain circumstances. Detailed computer simulations and comparisons are performed, confirming that the proposed ACF based schemes give satisfactory estimation performance over i.i.d. Rayleigh or Rician fading channels with various channel conditions.

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 Enhanced Low Speed Feedback for Closed Loop MIMO in OFDM Systems written by Igor Gutman and published by . This book was released on 2009 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book MIMO OFDM Wireless Communications with MATLAB written by Yong Soo Cho and published by John Wiley & Sons. This book was released on 2010-08-20 with total page 458 pages. Available in PDF, EPUB and Kindle. Book excerpt: MIMO-OFDM is a key technology for next-generation cellular communications (3GPP-LTE, Mobile WiMAX, IMT-Advanced) as well as wireless LAN (IEEE 802.11a, IEEE 802.11n), wireless PAN (MB-OFDM), and broadcasting (DAB, DVB, DMB). In MIMO-OFDM Wireless Communications with MATLAB®, the authors provide a comprehensive introduction to the theory and practice of wireless channel modeling, OFDM, and MIMO, using MATLAB® programs to simulate the various techniques on MIMO-OFDM systems. One of the only books in the area dedicated to explaining simulation aspects Covers implementation to help cement the key concepts Uses materials that have been classroom-tested in numerous universities Provides the analytic solutions and practical examples with downloadable MATLAB® codes Simulation examples based on actual industry and research projects Presentation slides with key equations and figures for instructor use MIMO-OFDM Wireless Communications with MATLAB® is a key text for graduate students in wireless communications. Professionals and technicians in wireless communication fields, graduate students in signal processing, as well as senior undergraduates majoring in wireless communications will find this book a practical introduction to the MIMO-OFDM techniques. Instructor materials and MATLAB® code examples available for download at www.wiley.com/go/chomimo

Download or read book The IEEE International Symposium on Personal Indoor and Mobile Radio Communications written by IEEE International Symposium on Personal, Indoor, and Mobile Radio Communications and published by . This book was released on 1995 with total page 832 pages. Available in PDF, EPUB and Kindle. Book excerpt: