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Equalization Of Underwater Acoustic Channel Using Independent Component Analysis Blind Signal Separation
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Book Synopsis Equalization of Underwater Acoustic Channel Using Independent Component Analysis Blind Signal Separation by : Fahad Ahmed Almassoud
Download or read book Equalization of Underwater Acoustic Channel Using Independent Component Analysis Blind Signal Separation written by Fahad Ahmed Almassoud and published by . This book was released on 2004 with total page 224 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Novel Adaptive Signal Processing Techniques for Underwater Acoustic Communications by :
Download or read book Novel Adaptive Signal Processing Techniques for Underwater Acoustic Communications written by and published by . This book was released on 2011 with total page 137 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Analysis of and Techniques for Adaptive Equalization for Underwater Acoustic Communication by : Ballard Justin Smith Blair
Download or read book Analysis of and Techniques for Adaptive Equalization for Underwater Acoustic Communication written by Ballard Justin Smith Blair and published by . This book was released on 2011 with total page 215 pages. Available in PDF, EPUB and Kindle. Book excerpt: Underwater wireless communication is quickly becoming a necessity for applications in ocean science, defense, and homeland security. Acoustics remains the only practical means of accomplishing long-range communication in the ocean. The acoustic communication channel is fraught with difficulties including limited available bandwidth, long delay-spread, time-variability, and Doppler spreading. These difficulties reduce the reliability of the communication system and make high data-rate communication challenging. Adaptive decision feedback equalization is a common method to compensate for distortions introduced by the underwater acoustic channel. Limited work has been done thus far to introduce the physics of the underwater channel into improving and better understanding the operation of a decision feedback equalizer. This thesis examines how to use physical models to improve the reliability and reduce the computational complexity of the decision feedback equalizer. The specific topics covered by this work are: how to handle channel estimation errors for the time varying channel, how to use angular constraints imposed by the environment into an array receiver, what happens when there is a mismatch between the true channel order and the estimated channel order, and why there is a performance difference between the direct adaptation and channel estimation based methods for computing the equalizer coefficients. For each of these topics, algorithms are provided that help create a more robust equalizer with lower computational complexity for the underwater channel.
Download or read book Chinese Journal of Acoustics written by and published by . This book was released on 2007 with total page 414 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Comparison of Channel Equalization Filtering Techniques in Underwater Acoustic Communications by : Ryan J. Kuchler
Download or read book Comparison of Channel Equalization Filtering Techniques in Underwater Acoustic Communications written by Ryan J. Kuchler and published by . This book was released on 2002-06-01 with total page 171 pages. Available in PDF, EPUB and Kindle. Book excerpt: In this thesis, underwater acoustic communications signal processing techniques which are used to equalize the distortional effects associated with the ocean as a communications channel, are investigated for a shallow water ocean environment. The majority of current signal processing techniques employ a Finite Impulse Response (FIR) filter. Three equalization filters were investigated and presented as alternatives; they were the passive time-reversed filter, the inverse filter, and the Infinite Impulse Response (IIR) filter. The main advantage of the passive time-reversed filter and the inverse filter is simplicity of design. Bit error rates for the time-reversed filter were consistently around 10(exp -1) and those for the inverse filter were greater than 10(exp -1). However, inability of the passive time-reversed filter to completely eliminate multipath components and the ill-conditioned nature offline inverse filter made it difficult to achieve Probability of Error results below 10(exp -1). Research into the development of an array receiver using a time- reversed filter should improve calculated bit error rates. Simulations of the IIR filter were conducted with limited success. The main advantage of an IIR filter is that fewer parameters are required in the design of the filter. However, the potential for instability in the filter is a significant limitation. Probability of Error results were found to be on the order of those for current FIR filters at close ranges. Unfortunately, instability issues arose for receivers as range from the source increased. This research on the IIR filter is still in the embryonic stage whereas research using FIR filters is relatively highly developed. Further research is needed to address the issue of instability in IIR filters in order to make them effective signal processing technique employable in underwater acoustic communications.
Book Synopsis Channel Equalization in Underwater Acoustic Communications Using Multiple Antennas by : Leili Baghaei Rad
Download or read book Channel Equalization in Underwater Acoustic Communications Using Multiple Antennas written by Leili Baghaei Rad and published by . This book was released on 2006 with total page 178 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Combined Spatial Diversity and Time Equalization for Broadband Multiple Channel Underwater Acoustic Communications by : Violeta Skoro Kaskarovska
Download or read book Combined Spatial Diversity and Time Equalization for Broadband Multiple Channel Underwater Acoustic Communications written by Violeta Skoro Kaskarovska and published by . This book was released on 2015 with total page 136 pages. Available in PDF, EPUB and Kindle. Book excerpt: High data rate acoustic communications become feasible with the use of communication systems that operate at high frequency. The high frequency acoustic transmission in shallow water endures severe distortion as a result of the extensive intersymbol interference and Doppler shift, caused by the time variable multipath nature of the channel. In this research a Single Input Multiple Output (SIMO) acoustic communication system is developed to improve the reliability of the high data rate communications at short range in the shallow water acoustic channel. The proposed SIMO communication system operates at very high frequency and combines spatial diversity and decision feedback equalizer in a multilevel adaptive configuration. The first configuration performs selective combining on the equalized signals from multiple receivers and generates quality feedback parameter for the next level of combining. The second configuration implements a form of turbo equalization to evaluate the individual receivers using the feedback parameters as decision symbols. The improved signals from individual receivers are used in the next iteration of selective combining. Multiple iterations are used to achieve optimal estimate of the received signal. The multilevel adaptive configuration is evaluated on experimental and simulated data using SIMO system with three, four and five receivers. The simulation channel model developed for this research is based on experimental channel and Rician fading channel model. The performance of the channel is evaluated in terms of Bit Error Rate (BER) and Signal-to-Noise-and-Interference Ratio (SNIR). Using experimental data with non-zero BER, multilevel adaptive spatial diversity can achieve BER of 0 % and SNIR gain of 3 dB. The simulation results show that the average BER and SNIR after multilevel combining improve dramatically compared to the single receiver, even in case of extremely high BER of individual received signals. The results demonstrate the ability of the proposed multilevel adaptive combining approach to significantly improve the performance of the shallow water acoustic channel, while preserving the same transmission power and channel bandwidth.
Book Synopsis From Blind to Semi-Blind Acoustic Source Separation Based on Independent Component Analysis by : Andreas Brendel
Download or read book From Blind to Semi-Blind Acoustic Source Separation Based on Independent Component Analysis written by Andreas Brendel and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Electrical & Electronics Abstracts by :
Download or read book Electrical & Electronics Abstracts written by and published by . This book was released on 1997 with total page 1860 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Underwater Acoustic Channel Modeling by : Bo Zhang
Download or read book Underwater Acoustic Channel Modeling written by Bo Zhang and published by . This book was released on 2011 with total page 68 pages. Available in PDF, EPUB and Kindle. Book excerpt: In recent years, interests in Underwater Acoustic (UWA) communications have exponentially grown due to many emerging commercial and military applications such as ocean pollution monitoring, off-shore oil exploration and data telemetry, oceanic environment sensing and surveillance, underwater wireless sensor networking, submarine communications, and so on. The UWA channels have specific properties which differ from radio channels, which make it a big challenge to apply current radio wireless systems to it directly. There are three main characters attached in UWA channels: low speed of sound that varies with medium conditions; attenuation that increases with both transmission range and frequency; time-varying multipath propagation that depends on boundary conditions. The wireless communication systems build on UWA channels would suffers from limited bandwidth, long multipath delays, large Doppler shift and spread which means low data rate, sever inter symbol interference (ISI) and complex equalization. The design and analysis of underwater acoustic communication systems rely on the fundamental characterization of underwater acoustic signal propagation. Several channel models have been developed to investigate channel properties in different environment set ups. Currently, there are no standardized models for acoustic channel fading. There are two kinds of models developed so far for different purposes: deterministic models and statistical models. While the former one focuses on the reflections when boundary conditions are fixed, the latter one concentrates on overall channel's statistical probability distributions with changing boundaries. Statistical models raise too much debate and the assumptions of the models with various statistical distributions remain to be further tested. On the other hand, many deterministic models have been tested and implemented as appropriate tools to investigate the reflection and refraction behavior of underwater acoustic signal propagation. In this thesis, we aim to study the power delay profile of underwater acoustic communication channels for given specific system configuration. Specifically, we investigated the multipath channel impulse responses of underwater acoustic channels by considering firstly a deterministic ray/beam tracing model and then a statistically random environment. We simulated an underwater acoustic channel model on MATLAB based on geometry of transceiver and surrounding environment and wave propagation equations. The amplitude and delays of the multipath channel impulse responses were compared and analyzed for underwater acoustic channels with various transceiver configurations such as range, depth, frequency, random water surface and bottom. Simulation results show that the depth location of underwater transceivers does not affect much the delay profile of the multipath received signals, however, it does change the power distribution of the multipath signals as the closer the transceiver to the boundaries, the less power received. Regarding various ranges between the transmitter and receiver, it is interesting to observe that the power delay profile of the multipath signals vary randomly, and the number of delay paths is uncorrelated to the ranges. Regarding underwater acoustic communication with different frequencies, while the delay profile of multipath signals remains stable with the same system geometry, the attenuation of multipath signals decreases as the frequency of acoustic signals increases. Moreover, the boundary conditions (water surface and/or bottom) of underwater acoustic channel affect the power delay profile of multipath signals significantly. In both fixed boundary and randomly varying boundary (e.g. water surface waves), the power delay profile of multipath signals exhibits a random pattern, which raises significant challenge in channel estimation in underwater acoustic communication. Our findings are helpful to the design of high-rate underwater acoustic communication systems. Our ultimate goal is to apply the MIMO-OFDM concept in underwater communication scenario in order to increase the date rate of underwater acoustic communication systems, in which channel estimation, channel multipath mitigation, signal processing, and data detection, need to be redesigned properly to take into account the unique characteristics of underwater acoustic channels.
Book Synopsis Iterative Equalization and Decoding Applied to Underwater Acoustic Communication by : James F. Sifferlen
Download or read book Iterative Equalization and Decoding Applied to Underwater Acoustic Communication written by James F. Sifferlen and published by . This book was released on 2008 with total page 134 pages. Available in PDF, EPUB and Kindle. Book excerpt: This dissertation focuses on data communication over shallow, long-range underwater acoustic (UWA) channels, which are characterized by relatively long, time-varying impulse responses and acute sensitivity to Doppler effects. The latter is a result of the slow speed of sound in water, while the former is a consequence of the waveguide nature of shallow, long-range UWA channels. A succession of novel receiver algorithms are developed which recover digital information transmitted across such channels. The first considers the case of a single, fixed source transducer transmitting information to a single, fixed receive hydrophone. The second extends the first to allow nontrivial source motion, for instance, that of an autonomous undersea vehicle. The third extends the second to allow processing of data received on an array of hydrophones. The algorithms employ iterative detection. Iterative processing is creating a paradigm shift in digital communication, made possible by ever-increasing computational capabilities. There are two major components to the algorithms: an equalizer and a decoder. The main focus of this dissertation is the former which, because of the features of the UWA channel, and since the channel is not assumed known a priori at the receiver, entails adaptive resampling to correct for Doppler distortion, adaptive filtering to estimate the time-varying channel, and adaptive equalization to compensate for intersymbol interference produced by the long channel impulse responses. While decoding is performed using standard methods, its role is nonetheless crucial to the overall functioning of the algorithms. In fact, they rely on the iterative exchange of information between equalizer and decoder, and the improvement of that information with each iteration. Successful performance of the algorithms is demonstrated using data from at-sea experiments.
Book Synopsis Frequency-Domain Channel Estimation and Equalization for Single Carrier Underwater Acoustic Communications by :
Download or read book Frequency-Domain Channel Estimation and Equalization for Single Carrier Underwater Acoustic Communications written by and published by . This book was released on 2007 with total page 7 pages. Available in PDF, EPUB and Kindle. Book excerpt: A new frequency-domain channel estimation and equalization (FDE) scheme is proposed for single carrier (SC) underwater acoustic communications. The proposed SC-FDE employs a small training signal block for initial channel estimation in the frequency domain and converts the estimated transfer function to a desired DFT (discrete Fourier transform) size for channel equalization of the data blocks. The frequency domain equalizer is designed using the linear minimum mean square error criterion. A new phase coherent detection scheme is also proposed and deployed to combat the phase drift due to the instantaneous Doppler in the underwater channels. The channel transfer functions and group-averaged phase drift are re-estimated adaptively in a decision-directed manner for each data block in a packet, which contains M blocks of QPSK data. The proposed SC-FDE method is applied to single input multiple output (SIMO) systems using the experimental data measured off the coast of Panama City, Florida, USA, June 2007. The uncoded bit error rate of the SIMO systems varies between 1.3% to 6.8 10( -5) when 4 tilde 8 receive hydrophones are utilized, and the source-receiver range is 5.06 km.
Book Synopsis Adaptive Channel Equalization in the Time-Varying Underwater Acoustic Channel: Performance Characterization and Robust Equalizers by :
Download or read book Adaptive Channel Equalization in the Time-Varying Underwater Acoustic Channel: Performance Characterization and Robust Equalizers written by and published by . This book was released on 2004 with total page 23 pages. Available in PDF, EPUB and Kindle. Book excerpt: Channel-estimate-based equalizers are adaptive coherent equalizers for which observations of the received signal are used to estimate channel parameters and these estimates are used to calculate the equalizer filter weights. Traditional channel-estimate- based equalizers calculate filter weights assuming that the estimates of the channel parameters are perfect. This work presents a common framework for evaluating both the performance of channel-estimate- based equalizers when the channel estimates are perfect (i.e. the minimal achievable error of the equalizer) and the degradation in performance of these equalizers due to errors in the channel estimates (i.e. the excess error). For the three type of equalizers considered (DFE Linear MMSE and Passive Time Reversal) the expressions for minimal achievable error take the form of the results from classical estimation theory for estimation error achieved by MMSE and matched filter estimators. These expressions are interpreted to give insights into the characteristics of "good" and "bad" channels. For the case when the channel estimates are MMSE estimates of the channel-impulse response, the excess error is shown to be proportional to the 2-norm of the calculated feedforward filter weight vector of the equalizer. This result is analogous to the "white noise gain" result characterizing the sensitivity of adaptive array processors to mismatch. This result is used to evaluate the relative sensitivity of all three types of equalizers to environmental mismatch. The analytic predictions of equalizer performance are compared with observed performance using data from several field experiments in different underwater acoustic environments. The expressions for minimal achievable error and excess error give insights into potential methods of improving the robustness to channel mismatch of adaptive equalizers such as the DFE. Several of these methods are implemented and evaluated.
Book Synopsis Underwater Acoustic Signal Processing by : Douglas A. Abraham
Download or read book Underwater Acoustic Signal Processing written by Douglas A. Abraham and published by . This book was released on 2019 with total page 834 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book provides comprehensive coverage of the detection and processing of signals in underwater acoustics. Background material on active and passive sonar systems, underwater acoustics, and statistical signal processing makes the book a self-contained and valuable resource for graduate students, researchers, and active practitioners alike. Signal detection topics span a range of common signal types including signals of known form such as active sonar or communications signals; signals of unknown form, including passive sonar and narrowband signals; and transient signals such as marine mammal vocalizations. This text, along with its companion volume on beamforming, provides a thorough treatment of underwater acoustic signal processing that speaks to its author’s broad experience in the field.
Book Synopsis Blind Source Separation of Audible Signals Using Independent Component Analysis by : Richard Carl Burnett
Download or read book Blind Source Separation of Audible Signals Using Independent Component Analysis written by Richard Carl Burnett and published by . This book was released on 1999 with total page 254 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Book Synopsis Computational Intelligence in Recent Communication Networks by : Mariya Ouaissa
Download or read book Computational Intelligence in Recent Communication Networks written by Mariya Ouaissa and published by Springer Nature. This book was released on 2022-02-21 with total page 279 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book focuses on the use of Artificial Intelligence and Machine Learning (AI/ML) based techniques to solve issues related to communication networks, their layers, as well as their applications. The book first offers an introduction to recent trends regarding communication networks. The authors then provide an overview of theoretical concepts of AI/ML, techniques and protocols used in different layers of communication. Furthermore, this book presents solutions that help analyze complex patterns in user data and ultimately improve productivity. Throughout, AI/ML-based solutions are provided, for topics such as signal detection, channel modeling, resource optimization, routing protocol design, transport layer optimization, user/application behavior prediction, software-defined networking, congestion control, communication network optimization, security, and anomaly detection. The book features chapters from a large spectrum of authors including researchers, students, as well as industrials involved in research and development.
Book Synopsis Pilot-tone Based ZP-OFDM Demodulation for an Underwater Acoustic Channel by : Baosheng Li
Download or read book Pilot-tone Based ZP-OFDM Demodulation for an Underwater Acoustic Channel written by Baosheng Li and published by . This book was released on 2007 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Existing coherent underwater acoustic communications systems rely on signal carrier transmission and adaptive decision feedback equalization to deal with time-varying and highly dispersive underwater acoustic (UWA) channels. Equalization complexity prevents any substantial rate improvement with the existing single-carrier approach, as the channel frequency selectivity increases considerably when the symbol rate increases. Multicarrier modulation in the form of orthognoal frequency division multiplexing (OFDM), on the other hand, converts a frequency selective channel into a set of parrallel frequency-flat subchannels, thus greatly simplifying receiver equalization. Motivated by the success of OFDM in radio channels, we investigate its use for underwater acoustic channels. In this paper, we develop a pilot-tone based receiver design for zero-padded OFDM transmissions, and test it in a real underwater acoustic channel. Our proposed receiver perofmrs carrier frequency offset compensations, channel estimation, and data demodulation on the basis of individual OFDM block. This approach is appealing to applications with short data bursts, or fast varying channels, as it does not rely on channel dependence across OFDM blocks.
