Channel Estimation and Equalization for Ultra-wideband Communications with Pulse Position Modulation
Channel Estimation and Equalization for Ultra-wideband Communications with Pulse Position Modulation

Author: Xiaofan Yang

Publisher:

Published: 2005

Total Pages: 94

ISBN-13:

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In this thesis we consider the design of an ultra-wideband (UWB) receiver. We investigate channel estimation and equalization algorithms of ultra-wideband radio with pulse position modulation. We propose a completely blind channel estimation method based on the first-order cyclostationarity in the received signal. In contrast to other blind UWB channel estimation methods, our algorithm exhibits low complexity and is robust for channels with large numbers of taps. We investigate equalization by introducing a discrete-time equivalent model for time-hopping pulse-position-modulated UWB systems. This equivalent model views the transmitter-channel-receiver system at symbol rate. The computational complexity is reduced by processing the received data at symbol rate instead of chip rate. Symbol detection techniques including decision feedback equalization and maximum likelihood detection are evaluated and compared with correlation detection. Chapter 1 is an introduction to UWB systems, including the development of the technology, current research topics, and recent applications. Chapters 2 and 3 study the channel estimation and equalization problems, respectively. Chapter 4 summarizes the thesis and presents possible future work.

Estimation of Sparse Channels in IR-UWB Systems
Estimation of Sparse Channels in IR-UWB Systems

Author: Maryam Vala

Publisher:

Published: 2014

Total Pages:

ISBN-13:

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"Ultra Wideband (UWB) is a rapidly growing technology for digital wireless communications. UWB utilizes low power, ultra short, pulses and is specifically suited for short-range, high-rate indoor wireless communications as well as fine localization applications. The attractive properties of UWB are a direct consequence of its very wide bandwidth that also implies an extremely high Nyquist sampling rate, so digital processing of UWB signals requires the use of fast and efficient, and therefore, expensive, Analog to Digital Converters. UWB systems are commonly used in indoor environments in which propagation is characterized by long but sparse multipath channels. Multi-path channels cause inter symbol interference (ISI) and introduce distortion to the received signal. To counter the effects of the channel, the channel impulse response must be accurately estimated at the receiver. There are two main estimation approaches for UWB channels: Compressed Sensing (CS)-based and Adaptive Filter (AF)-based. The former combine sampling and compression into a single linear measurement process that operates at sub-Nyquist rate by capitalizingon the sparsity of UWB signals. The latter, uses Least-Mean-Square filtering principles to obtain low complexity channel estimation methods. The problem we consider in this thesisis the estimation of a long sparse multi-path channel in an UWB system. We focus on systems that use Pulse Position Modulation (PPM) that is one of the most commonly used modulation schemes in UWB systems. We review CS and AF based methods and then we propose new AF-type methods specifically for the estimation of sparse multi-path channels with PPM inputs. The main idea behind the proposed methods is to estimate the long channel in sections in order to reduce the computational cost and improve the estimation performance. Finally, we present simulation results showing the superior performance of the proposed algorithms." --

Modulation and Multiple Access Techniques for Ultra-wideband Communication Systems
Modulation and Multiple Access Techniques for Ultra-wideband Communication Systems

Author: Song Cui

Publisher:

Published: 2011

Total Pages: 155

ISBN-13:

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Two new energy detection (ED) Ultra-Wideband (UWB) systems are proposed in this dissertation. The first one is an ED UWB system based on pulse width modulation (PWM). The bit error rate (BER) performance of this ED PWM system is slightly worse than ED pulse position modulation (PPM) system in additive white Gaussian noise (AWGN) channels. However, the BER performance of this ED PWM system surpasses that of a PPM system in multipath channels since a PWM system does not suffer cross-modulation interference (CMI) as a PPM system. In the presence of synchronization errors, the BER performance of a PWM system also surpasses that of a PPM system. The second proposed ED UWB system is based on using two pulses, which are the different-order derivatives of the Gaussian pulse, to transmitted bit 0 or 1. These pulses are appropriately chosen to separate their spectra in frequency domain. The receiver is composed of two energy detection branches and each branch has a filter which captures the signal energy of either bit 0 or 1. The outputs of two branches are subtracted from each other to generate the decision statistic and the value of this statistic is compared to a threshold to determine the transmitted bits. This system is named as acf{GFSK} system in this dissertation and it exhibits the same BER performance as a PPM system in AWGN channels. In multipath channels, a GFSK system surpasses a PPM system because it does not suffer CMI. And the BER performance of a GFSK system is better than a PPM system in the presence of synchronization errors. When a GFSK system is compared to a PWM system, it will always achieve approximately 2 dB improvement in AWGN channels, multipath channels, and in the presence synchronization errors. However, a PWM system uses lower-order derivatives of the Gaussian pulse to transmit signal, and this leads to a simple pulse generator. In this dissertation, an optimal threshold is applied to improve PPM system performance. The research results show that the application of an optimal threshold can effectively mitigate the effect of CMI and synchronization errors and achieve performance improvement. Finally, the multiple access schemes are discussed and time hopping is chosen as the multiple access scheme for PWM and GFSK systems.

Ultra Wideband Communications
Ultra Wideband Communications

Author: Mohammad Abdul Matin

Publisher: BoD – Books on Demand

Published: 2011-07-27

Total Pages: 364

ISBN-13: 9533074612

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This book has addressed few challenges to ensure the success of UWB technologies and covers several research areas including UWB low cost transceiver, low noise amplifier (LNA), ADC architectures, UWB filter, and high power UWB amplifiers. It is believed that this book serves as a comprehensive reference for graduate students in UWB technologies.

Ultra Wideband Systems with MIMO
Ultra Wideband Systems with MIMO

Author: Thomas Kaiser

Publisher: John Wiley & Sons

Published: 2010-03-18

Total Pages: 266

ISBN-13: 9780470740002

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Up-to-date coverage of the cutting-edge research on UWB Systems with Multiple Antennas In this book, the authors investigate the benefits of combining UWB and MIMO technologies; highlighting five aspects of this promising research field: channel capacity, space-time coding, beamforming and localization, time-reversal transmission, and UWB-MIMO relay. The book presents a systematic and in-depth discussion for each of the hot topics, providing an insight into the cutting-edge research currently undertaken. It is expected that the ideas and approaches illustrated in this book will inspire sparks for the emerging technologies in short-range high data-rate wireless communications and other related applications. Key Features: Provides a thorough coverage combining the UWB and MIMO, outlining the opportunities and benefits created by the combination of these technologies Highlights five aspects of this promising research field: channel capacity, space-time coding, beamforming and localization, time-reversal transmission, and UWB-MIMO relay Covers UWB-MIMO channel measurement and models This book will serve as an invaluable reference for academic and professional researchers in wireless communications, and graduate students. Engineers and technical professionals will also find the book insightful

On Ultra Wideband Channel Estimation Using Compressed Sensing
On Ultra Wideband Channel Estimation Using Compressed Sensing

Author: Maise Tamouh Al Atassi

Publisher:

Published: 2011

Total Pages: 100

ISBN-13:

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Due to the desirable characteristics of Ultra Wideband (UWB) signals, modern-day wireless communications systems are becoming increasingly designed to use such signals. However, UWB technology faces many challenges such as the extremely high sampling rate, the large channel length and the complicated receiver design. These challenges call for adopting a new technique that overcomes the demanding Shannon-Nyquist approach for sampling and allows for signal reconstructions using a fewer number of measurements, such as Compressed Sensing (CS). In this thesis, the theory of CS is employed as part of the UWB channel estimation process using greedy algorithms. We study the performance of a variety of greedy reconstruction algorithms including "Matching Pursuit" and "Weighted Matching Pursuit", under different types of measurement matrices while taking into consideration the effect of additive noise on the performance of the system. We propose two novel greedy reconstruction algorithms: "Block-wise Matching Pursuit" and "Bayesian Weighted Matching Pursuit", and prove that they outperform existing reconstruction algorithms in terms of execution time and power consumption.

Semi-Blind Carrier Frequency Offset Estimation and Channel Equalization
Semi-Blind Carrier Frequency Offset Estimation and Channel Equalization

Author: Yufei Jiang

Publisher: Springer

Published: 2015-12-01

Total Pages: 96

ISBN-13: 3319249843

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This SpringerBrief investigates the performance of semi-blind independent component analysis (ICA) based equalization and carrier frequency offset estimation approaches (CFO) for a number of orthogonal frequency division multiplexing (OFDM) based wireless communication systems. It provides a comprehensive overview of the challenges of channel equalization and frequency synchronization for different wireless systems. The authors present the wireless communication channel and system models. Key existing CFO estimation methods are reviewed, along with a number of the training based and non-training based (blind) channel estimation methods. This is followed by a study of ICA and its applications to OFDM-based wireless communication systems. Later chapters provide a detailed description of recent research on semi-blind CFO estimation and ICA based equalization approaches for various wireless communication systems including multiple-input multiple-output (MIMO) OFDM and coordinated multipoint (CoMP) systems. Semi-blind CFO estimation and equalization structures provide a spectrum-efficient and high-performance solution for high speed wireless communications. This book is suitable for postgraduate students, researchers or professionals in the area of wireless communications.