Download or read book Adaptive Technique for Underwater Acoustic Communication written by Shen Xiaohong and published by . This book was released on 2012 with total page pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive Technique for Underwater Acoustic Communication.

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:

Download or read book Underwater Acoustics written by Salah Bourennane and published by BoD – Books on Demand. This book was released on 2012-03-28 with total page 146 pages. Available in PDF, EPUB and Kindle. Book excerpt: The field of acoustic engineering has many various potential applications, such as in ocean science research and homeland security. This book provides cutting-edge knowledge in current techniques and technologies, such as the adaptive technique for underwater communication, array processing and the CI/OFDM system. One chapter takes inspiration from the natural world in proposing a new bio-inspired ranging approach for resolution purposes. Technologies such as high-resolution array processing methods can also be used to locate underwater objects in sediment, as one chapter shows. Finally, two contributions cover the applications of narrowband interference suppression and iterative equalization, and decoding schemes. Given the scope of the book, it will be required reading for researchers and engineers in the field.

Download or read book Digital Underwater Acoustic Communications written by Lufen Xu and published by Academic Press. This book was released on 2016-09-16 with total page 292 pages. Available in PDF, EPUB and Kindle. Book excerpt: Digital Underwater Acoustic Communications focuses on describing the differences between underwater acoustic communication channels and radio channels, discusses loss of transmitted sound in underwater acoustic channels, describes digital underwater acoustic communication signal processing, and provides a comprehensive reference to digital underwater acoustic communication equipment. This book is designed to serve as a reference for postgraduate students and practicing engineers involved in the design and analysis of underwater acoustic communications systems as well as for engineers involved in underwater acoustic engineering. Introduces the basics of underwater acoustics, along with the advanced functionalities needed to achieve reliable communications in underwater environment Identifies challenges in underwater acoustic channels relative to radio channels, underwater acoustic propagation, and solutions Shows how multi-path structures can be thought of as time diversity signals Presents a new, robust signal processing system, and an advanced FH-SS system for multimedia underwater acoustic communications with moderate communication ranges (above 20km) and rates (above 600bps) Describes the APNFM system for underwater acoustic communication equipment (including both civil and military applications), to be employed in active sonar to improve its performance

Download or read book Adaptive Methods in Underwater Acoustics written by H.G. Urban and published by Springer Science & Business Media. This book was released on 2012-12-06 with total page 763 pages. Available in PDF, EPUB and Kindle. Book excerpt: The NATO Advanced Study Institute on Adaptive Methods in Underwater Acoustics was held on 30 July - 10 August 1984 in LLineburg, Germany. The Institute was primarily concerned with signal processing for underwater appl ica tions. The majority of the presentations, when taken together, yield a definite picture of the present status of understanding of adaptive and high resolution processing, setting out the progress achieved over the past four years together with the major problem areas remaining. Major effort was made to obtain a commensurate contribution of tutorial and advanced research papers. It is my hope that the material in this volume may be equally well suited for students getting an introduction to some of the basic problems in underwater signal processing and for the professionals who may obtain an up-to-date overview of the present state of the art. This might be especially useful in view of the controversy and lack of adequate interrelationships which have marked this rapidly expanding field in the past. Practical reinforcement of this picture is provided by the material concerning digital and optical processing technology, giving some guidance to achievable adaptive and high resolution techniques with current processing devices. The formal programme was extended and detailed by a series of six evening work shops on specific topics, during which informal discussions took place among the participants. Summaries of these workshops are also included in these Proceedings.

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 Cognitive Underwater Acoustic Networking Techniques written by Dimitri Sotnik and published by Springer Nature. This book was released on 2020-09-29 with total page 89 pages. Available in PDF, EPUB and Kindle. Book excerpt: This book summarizes the latest research on cognitive network-layer methods and smart adaptive physical-layer methods in underwater networks. Underwater communication requires extendable and delay-tolerant underwater acoustic networks capable of supporting multiple frequency bands, data rates and transmission ranges. The book also discusses a suitable foreground communication stack for mixed mobile/static networks, a technology that requires adaptive physical layer waveforms and cognitive network strategies with underlying cooperative and non-cooperative robust processes. The goal is to arrive at a universally applicable standard in the area of Underwater Internet-of-Things [ISO/IEC 30140, 30142, 30143]. The book is the second spin-off of the research project RACUN, after the first RACUN-book "Underwater Acoustic Networking Techniques" (https://link.springer.com/book/10.1007%2F978-3-642-25224-2)

Download or read book Underwater Acoustic Digital Signal Processing and Communication Systems written by Robert Istepanian and published by Springer Science & Business Media. This book was released on 2013-03-09 with total page 283 pages. Available in PDF, EPUB and Kindle. Book excerpt: Underwater acoustic digital signal processing and communications is an area of applied research that has witnessed major advances over the past decade. Rapid developments in this area were made possible by the use of powerful digital signal processors (DSPs) whose speed, computational power and portability allowed efficient implementation of complex signal processing algorithms and experimental demonstration of their performance in a variety of underwater environments. The early results served as a motivation for the development of new and improved signal processing methods for underwater applications, which today range from classical of autonomous underwater vehicles and sonar signal processing, to remote control underwater wireless communications. This book presents the diverse areas of underwater acoustic signal processing and communication systems through a collection of contributions from prominent researchers in these areas. Their results, both new and those published over the past few years, have been assembled to provide what we hope is a comprehensive overview of the recent developments in the field. The book is intended for a general audience of researchers, engineers and students working in the areas of underwater acoustic signal processing. It requires the reader to have a basic understanding of the digital signal processing concepts. Each topic is treated from a theoretical perspective, followed by practical implementation details. We hope that the book can serve both as a study text and an academic reference.

Download or read book Direct form Adaptive Equalization for Underwater Acoustic Communication written by Atulya Yellepeddi and published by . This book was released on 2012 with total page 143 pages. Available in PDF, EPUB and Kindle. Book excerpt: Adaptive equalization is an important aspect of communication systems in various environments. It is particularly important in underwater acoustic communication systems, as the channel has a long delay spread and is subject to the effects of time- varying multipath fading and Doppler spreading. The design of the adaptation algorithm has a profound influence on the performance of the system. In this thesis, we explore this aspect of the system. The emphasis of the work presented is on applying concepts from inference and decision theory and information theory to provide an approach to deriving and analyzing adaptation algorithms. Limited work has been done so far on rigorously devising adaptation algorithms to suit a particular situation, and the aim of this thesis is to concretize such efforts and possibly to provide a mathematical basis for expanding it to other applications. We derive an algorithm for the adaptation of the coefficients of an equalizer when the receiver has limited or no information about the transmitted symbols, which we term the Soft-Decision Directed Recursive Least Squares algorithm. We will demonstrate connections between the Expectation-Maximization (EM) algorithm and the Recursive Least Squares algorithm, and show how to derive a computationally efficient, purely recursive algorithm from the optimal EM algorithm. Then, we use our understanding of Markov processes to analyze the performance of the RLS algorithm in hard-decision directed mode, as well as of the Soft-Decision Directed RLS algorithm. We demonstrate scenarios in which the adaptation procedures fail catastrophically, and discuss why this happens. The lessons from the analysis guide us on the choice of models for the adaptation procedure. We then demonstrate how to use the algorithm derived in a practical system for underwater communication using turbo equalization. As the algorithm naturally incorporates soft information into the adaptation process, it becomes easy to fit it into a turbo equalization framework. We thus provide an instance of how to use the information of a turbo equalizer in an adaptation procedure, which has not been very well explored in the past. Experimental data is used to prove the value of the algorithm in a practical context.

Download or read book Underwater Acoustic Networking Techniques written by Roald Otnes and published by Springer Science & Business Media. This book was released on 2012-01-19 with total page 93 pages. Available in PDF, EPUB and Kindle. Book excerpt: This literature study presents an overview of underwater acoustic networking. It provides a background and describes the state of the art of all networking facets that are relevant for underwater applications. This report serves both as an introduction to the subject and as a summary of existing protocols, providing support and inspiration for the development of network architectures.

Download or read book Adaptive Methods in Underwater Acoustics written by H. G. Urban and published by . This book was released on 1985-04-30 with total page 804 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Adaptive Modulation Techniques for Underwater Acoustic Channels written by Sanjay Mani and published by . This book was released on 2008 with total page 218 pages. Available in PDF, EPUB and Kindle. Book excerpt:

Download or read book Underwater Acoustic Sensor Networks written by Yang Xiao and published by CRC Press. This book was released on 2010-05-19 with total page 352 pages. Available in PDF, EPUB and Kindle. Book excerpt: A detailed review of underwater channel characteristics, Underwater Acoustic Sensor Networks investigates the fundamental aspects of underwater communication. Prominent researchers from around the world consider contemporary challenges in the development of underwater acoustic sensor networks (UW-ASNs) and introduce a cross-layer approach for effec

Download or read book Reinforcement Learning Based Mobile Underwater Acoustic Communications written by Qiang Fu and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: Underwater acoustic communication technologies are becoming increasingly important due to the widespread adoption of autonomous unmanned vehicles (AUVs) in ocean data collection. The communication support provided by acoustic telemetry makes it possible for multiple AUVs to coordinate during underwater missions. Mobile underwater acoustic communications is still an active field of research. Various technical issues, such as reliable communications between two mobile nodes, multi-user communications, and joint optimization of navigation and communications are awaiting for satisfactory solutions. In this thesis, we develop solutions for several of these issues. The first effort considers an adaptive communication system based on time-reversed orthogonal frequency-division multiplexing methods for the underwater acoustic channels. In this adaptive system, the receiver sends truncated q-functions to the transmitter, which then performs mapping selection for the individual sub-carriers. Simulations demonstrate the advantages of the proposed adaptive system, achieving higher data rates and lower feedback costs. The second effort addresses the extended propagation delay in closed-loop adaptive communications for mobile platforms. An adaptive modulation strategy is developed based on reinforcement learning. Specifically, a Dyna-Q algorithm is presented to improve the communication throughput. Our simulations show that the Dyna-Q algorithm achieves a higher throughput and lower bit-error-rates than the direct feedback. The third effort provides a solution to the acoustic communication problem with multiple AUVs. We propose a virtual multiple-input/multiple-output (MIMO) strategy that selects transmitters from a subset of AUVs to form a virtual transmit array. A user selection algorithm is used to determine the active AUV subset for data transmissions. Adaptive modulation is combined to further improve throughput. The user selection and modulation choice are determined by the predicted data rates, thus increasing spectral efficiency of the uplink. In the last effort of this thesis, we address the trajectory optimization for underwater data muling with mobile nodes. In this scenario, multiple AUVs sample a mission area and autonomous surface vehicles (ASVs) visit underway AUVs to retrieve survey data. We propose a nearest-K reinforcement learning algorithm to optimize ASV travel tracks. The learning-based algorithm can simultaneously maximize fairness in data transmissions and minimize the travel distance of the surface nodes.

Download or read book OFDM for Underwater Acoustic Communications written by Sheng Zhou and published by John Wiley & Sons. This book was released on 2014-06-03 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: A blend of introductory material and advanced signal processing and communication techniques, of critical importance to underwater system and network development This book, which is the first to describe the processing techniques central to underwater OFDM, is arranged into four distinct sections: First, it describes the characteristics of underwater acoustic channels, and stresses the difference from wireless radio channels. Then it goes over the basics of OFDM and channel coding. The second part starts with an overview of the OFDM receiver, and develops various modules for the receiver design in systems with single or multiple transmitters. This is the main body of the book. Extensive experimental data sets are used to verify the receiver performance. In the third part, the authors discuss applications of the OFDM receiver in i) deep water channels, which may contain very long separated multipath clusters, ii) interference-rich environments, where an unintentional interference such as Sonar will be present, and iii) a network with multiple users where both non-cooperative and cooperative underwater communications are developed. Lastly, it describes the development of a positioning system with OFDM waveforms, and the progress on the OFDM modem development. Closely related industries include the development and manufacturing of autonomous underwater vehicles (AUVs) and scientific sensory equipment. AUVs and sensors in the future could integrate modems, based on the OFDM technology described in this book. Contents includes: Underwater acoustic channel characteristics/OFDM basics/Peak-to-average-ratio control/Detection and Doppler estimation (Doppler scale and CFO)/Channel estimation and noise estimation/A block-by-block progressive receiver and performance results/Extensions to multi-input multi-output OFDM/Receiver designs for multiple users/Cooperative underwater OFDM (Physical layer network coding and dynamic coded cooperation)/Localization with OFDM waveforms/Modem developments A valuable resource for Graduate and postgraduate students on electrical engineering or physics courses; electrical engineers, underwater acousticians, communications engineers

Download or read book Adaptive Reception for Underwater Communications written by Spyridon Dessalermos and published by . This book was released on 2011 with total page 164 pages. Available in PDF, EPUB and Kindle. Book excerpt: This research concerns the development of an adaptive receiver for underwater communication. In this type of wireless link, the radio channel is replaced by an underwater acoustic channel, which is strongly dependent on the physical properties of the ocean medium and its boundaries, the link geometry and the ambient noise. Traditional acoustic communications have involved a priori matching of the signaling parameters to the expected characteristics of the channel. To achieve more robust communications, as well as high quality of service, it is necessary to develop a type of adaptive receiver for the acoustic link. This process involves estimating the channel scattering function by processing the received Direct Sequence Spread Spectrum (DSSS) acoustic signal. This information is used by an innovative receiver introduced for usage in the underwater environment. The research also involves the development of a robust acquisition system for the acoustic communication signal. The major design goal is the receiver's robustness on a Doppler distorted fast varying multipath fading channel, for applications in multiuser environments. Another important design goal is low complexity in signal processing. The proposed receiver is able to adapt in the acoustic channel variations. Experimental results prove the effectiveness of the receiver.

Download or read book The Research on Adaptive and Machine Learning Methods in Underwater Acoustic Channel Estimation written by Yonglin Zhang and published by . This book was released on 2022 with total page 0 pages. Available in PDF, EPUB and Kindle. Book excerpt: The ocean covers more than 70% of the earth, which provides rich biological, chemical, mineral and space resources for the development of human civilization. The cause of managing the ocean is of strategic importance to our economic development and national security. Acoustic wave is the most widely used and mature underwater information transmission carrier known to mankind. Underwater acoustic (UWA) communication technology is one of the main technical supports to carry out various marine activities, but it is challenged by the complex marine environment, specifically in terms of propagation loss, UWA environmental noise, multipath propagation characteristics, Doppler expansion, spatial and temporal variation effects and other scientific issues, which restricts the improvements of the bit error rate (BER) performance, communication rate, communication distance, robustness and other indicators. The current level of development of UWA communication technology is difficult to fully meet the needs of practical applications.Channel estimation is an effective technical means to solve the problems of multipath effect and temporal- spatial variation characteristics. Recent breakthroughs in adaptive methods and machine learning in various fields have brought new opportunities for the further development of UWA channel estimation technology, but also raised new technical problems, such as the use of channel structure characteristics, sample scarcity training, label missing training, domain mismatch caused by environmental changes. These problems make the effectiveness and applicability of the new method seriously restricted, and it is difficult to bring out the proper information sensing ability.Based on the frontier of intelligent ocean and marine information science, this thesis focuses on the scientific problems of UWA communication in complex marine environment according to the development needs of national marine strategy, aims at the key technical problems faced by adaptive and machine learning channel estimation methods, such as analysis of channel cluster sparsity characteristics, limited data, label missing, domain mismatch, etc., and introduces optimization methods, neural network model design and analysis, data augmentation methods, transfer learning and other recent academic results. We have explored the mechanism of adaptive and machine learning based channel estimation methods and finally proposed a series of new methods for channel estimation based on adaptive signal processing and machine learning.