39 research outputs found

    Multiple Antenna-based GPS Multipath Mitigation using Code Carrier Information

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    ํ•™์œ„๋…ผ๋ฌธ (๋ฐ•์‚ฌ)-- ์„œ์šธ๋Œ€ํ•™๊ต ๋Œ€ํ•™์› : ์ „๊ธฐ๊ณตํ•™๋ถ€, 2013. 8. ์ตœ์ง„์˜.์—ฌ๋Ÿฌ ์‘์šฉ๋ถ„์•ผ์—์„œ ์ˆ˜ ์–ต๋Œ€์˜ GPS(Global Positioning System) ์ˆ˜์‹ ๊ธฐ๊ฐ€ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ์ง€๋งŒ, GPS์„ ๊ธฐ๋ฐ˜์œผ๋กœ ํ•˜๋Š” ์œ„์น˜๊ธฐ๋ฐ˜ ์„œ๋น„์Šค(LBS: Location Based Services)์—์„œ๋Š” ์—ฌ์ „ํžˆ ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ์™€ ๊ฐ™์€ ์ „ํŒŒ ๋ฐฉํ•ด๊ฐ€ ๋ฐœ์ƒํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ์˜ค์ฐจ๋“ค๋กœ ์ธํ•˜์—ฌ ์ƒ๊ด€ํ•จ์ˆ˜์˜ ์™œ๊ณก์€ ๊ฑฐ๋ฆฌ ์˜ค์ฐจ๊ฐ€ ๋ฐœ์ƒ์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์ด์œ ๋กœ ์ธํ•˜์—ฌ GPS์„ ์ด์šฉํ•œ ํ•ญ๋ฒ• ์‹œ์Šคํ…œ์—์„œ์˜ ์œ„์น˜ ์ •ํ™•๋„ ํ–ฅ์ƒ์„ ์œ„ํ•˜์—ฌ, ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ๋ฅผ ํšจ๊ณผ ์ ์œผ๋กœ ์ค„์ด๊ธฐ ์œ„ํ•œ ๊ฐ•์ธํ•˜๊ณ  ํ˜„์‹ค์ ์ธ ๋ฐฉ๋ฒ•์ด ์š”๊ตฌ๋œ๋‹ค. ๋‹ค์ค‘๊ฒฝ๋กœ๋Š” GPS ์‹ ํ˜ธ๊ฐ€ ์žฅ์• ๋ฌผ์— ์˜ํ•ด ๋ฐ˜์‚ฌ๋‚˜ ํšŒ์ ˆ ๋˜์–ด ์ˆ˜์‹ ๊ธฐ์— ๋„์ฐฉํ•  ๋•Œ ์ž˜ ์ผ์–ด๋‚œ๋‹ค. ๊ฐ€์‹œ๊ฒฝ๋กœ ์‹ ํ˜ธ์— ๊ฒฐํ•ฉ๋œ ๋‹ค์ค‘๊ฒฝ๋กœ ์‹ ํ˜ธ๋Š” GPS ์ˆ˜์‹ ๊ธฐ์˜ ์ƒ๊ด€ํ•จ์ˆ˜์˜ ๋ณ€ํ˜•์„ ์ผ์œผํ‚ค๋ฉฐ ๊ถ๊ทน์ ์œผ๋กœ ์ฐจ๋ณ„ํ•จ์ˆ˜์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋ฏ€๋กœ ๊ฑฐ๋ฆฌ์˜ค์ฐจ๋ฅผ ๋ฐœ์ƒ์‹œํ‚จ๋‹ค. ๊ทธ๋Ÿฌ๋ฏ€๋กœ ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ๋Š” ์œ„์„ฑํ•ญ๋ฒ• ์‹œ์Šคํ…œ์—์„œ์˜ ์œ„์น˜์ •ํ™•๋„ ํ–ฅ์ƒ์„ ์œ„ํ•ด ํ•ด๊ฒฐ ๋˜์–ด์•ผ ๋  ๋ฌธ์ œ๋กœ ์Ÿ์ ์ด ๋˜์–ด์™”๋‹ค. ์ตœ๊ทผ์—๋Š” ์ด๋Ÿฌํ•œ ์ „ํŒŒ ๊ฐ„์„ญ์‹ ํ˜ธ๋ฅผ ์ค„์ด๊ธฐ ์œ„ํ•˜์—ฌ ๋‹ค์ค‘๊ฐœ์˜ ์•ˆํ…Œ๋‚˜(Multiple Antenna)๋ฅผ ์ด์šฉํ•˜๋Š” ๋ฐฉ๋ฒ•์ด GPS ํ•ญ๋ฒ• ์‹œ์Šคํ…œ์—์„œ ์ด์šฉ๋˜๊ณ  ์žˆ๋‹ค. ํ˜„ ์‹œ์ ์—์„œ, ๋‹ค์ค‘๊ฐœ์˜ ์•ˆํ…Œ๋‚˜๋ฅผ ์‚ฌ์šฉํ•˜๋Š” ์‘์šฉ๋ถ„์•ผ๋Š” ์ฃผ๋กœ ํ•™์ˆ ์ ์ธ ์—ฐ๊ตฌ ๋ฐ ๋ณต์žกํ•œ ๊ตฐ์‚ฌ์šฉ ์—ฐ๊ตฌ๋กœ ์ฃผ๋กœ ์ง„ํ–‰ ๋˜์—ˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ์•ˆํ…Œ๋‚˜ ์ œ์ž‘ ๋ฐฉ๋ฒ• ๋ฐ ์ „๊ธฐ์  ์‹œ์Šคํ…œ์˜ ๊ธ‰๊ฒฉํ•œ ๋ฐœ์ „์œผ๋กœ ์ธํ•ด ์ด์ „์˜ ํ•˜๋“œ์›จ์–ด ๋ฐ ์†Œํ”„์›จ์–ด์ ์ธ ๋ฌธ์ œ๋ฅผ ์‰ฝ๊ฒŒ ํ•ด๊ฒฐ ๋จ์— ๋”ฐ๋ผ ๊ฐ€๊นŒ์šด ๋ฏธ๋ž˜์—๋Š” ๋‹ค์ค‘ ์•ˆํ…Œ๋‚˜ ๊ธฐ๋ฐ˜์˜ ์ˆ˜์‹ ๊ธฐ๊ฐ€ ๋ฏผ๊ฐ„ ์ƒ์šฉ๋ถ„์•ผ๋กœ ํ™•๋Œ€ ๋  ๊ฒƒ์œผ๋กœ ์˜ˆ์ƒ์ด ๋œ๋‹ค. ๋˜ํ•œ ์•ˆํ…Œ๋‚˜ ์ˆ˜์‹ ๊ธฐ RF๋‹จ์˜ ์†Œํ˜•ํ™”๋กœ ์ธํ•˜์—ฌ ๋‹ค์ค‘ ์•ˆํ…Œ๋‚˜ ์‹œ์Šคํ…œ์—์„œ์˜ ์•ˆํ…Œ๋‚˜ ํฌ๊ธฐ ๋ฌธ์ œ์  ๋˜ํ•œ ํ•ด๊ฒฐ ๊ฐ€๋Šฅํ•˜๋‹ค. ๊ทธ๋Ÿฌ๋ฏ€๋กœ ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ๋‹ค์ค‘ GPS ์•ˆํ…Œ๋‚˜๋ฅผ ์ด์šฉํ•˜์—ฌ GPS ํ•ญ๋ฒ•์—์„œ์˜ ์ „ํŒŒ ๊ฐ„์„ญ ๋ฐ ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ ๊ฐ์‡„์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋ฅผ ๋ชฉ์ ์œผ๋กœ ํ•œ๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋Š” ๊ฐ•ํ•œ ์ „ํŒŒ ๊ฐ„์„ญ ๋ฐ ๋‹ค์ค‘๊ฒฝ๋กœ ์‹ ํ˜ธ์— ๋Œ€ํ•˜์—ฌ ๊ณต๊ฐ„ ์ฒ˜๋ฆฌ ๊ธฐ๋ฒ•์„ ์ ์šฉํ•œ๋‹ค. ์ œ์•ˆ๋œ ์ƒˆ๋กœ์šด ๋ฐฉ๋ฒ•์€ ๋‹ค์ค‘ ์•ˆํ…Œ๋‚˜๋ฅผ ๊ธฐ๋ฐ˜์˜ ์ฝ”๋“œ ์ผ€๋ฆฌ์–ด ์ •๋ณด๋ฅผ ์ด์šฉํ•œ ๊ณต๊ฐ„์ฒ˜๋ฆฌ ๊ธฐ๋ฒ•์œผ๋กœ ์ „ํŒŒ ๊ฐ„์„ญ ๋ฐ ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ๋ฅผ ์™„ํ™”์‹œํ‚ค๋ฉฐ, ๋˜ํ•œ ๋น”ํ˜•์„ฑ ๊ธฐ๋ฒ•์„ ์ด์šฉํ•˜์—ฌ ์‹ ํ˜ธ ๋Œ€ ์žก์Œ ๋น„์œจ์„ ์ตœ๋Œ€๋กœ ํ•œ๋‹ค. ์ œ์•ˆ๋œ ์„ฑ๋Šฅ์„ ๊ฒ€์ฆํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ์†Œํ”„ํŠธ์›จ์–ด GPS ์ˆ˜์‹ ๊ธฐ๋ฅผ ์‚ฌ์šฉ๋œ๋‹ค. ์†Œํ”„ํŠธ์›จ์–ด GPS ์ˆ˜์‹ ๊ธฐ๋ฅผ ์ด์šฉํ•œ ์‹ ํ˜ธ์ฒ˜๋ฆฌ ๊ธฐ๋ฒ•์€ ์ƒˆ๋กœ์šด ์žฅ๋น„์˜ ์ œํ’ˆํ™” ๋ฐ GPS ์‹ ํ˜ธ ๋ถ„์„์— ์žฅ์ ์„ ๊ฐ€์ง€๊ณ  ์žˆ๋‹ค. ๋˜ํ•œ GPS ์•Œ๊ณ ๋ฆฌ์ฆ˜ ๋ถ„์„ ๋ฐ ์ˆ˜์‹ ๊ธฐ ์„ฑ๋Šฅ ํ–ฅ์ƒ ๊ฒ€์ฆ ๋“ฑ ์—ฌ๋Ÿฌ ์—ฐ๊ตฌ๋ถ„์•ผ์—์„œ ๋„๋ฆฌ ์ด์šฉ๋˜๊ณ  ์žˆ๋‹ค. ๋ณธ ๋…ผ๋ฌธ์—์„œ๋Š” ์ œ์•ˆ๋œ ๋ฐฉ๋ฒ•์˜ ์„ฑ๋Šฅ ๊ฒ€์ฆ์„ ์œ„ํ•˜์—ฌ ์ปดํ“จํ„ฐ ์‹œ๋ฎฌ๋ ˆ์ด์…˜ ๋ฐ ๊ฐ€๊ณต IF ๋ฐ์ดํ„ฐ๋ฅผ ์ด์šฉํ•œ ์†Œํ”„ํŠธ์›จ์–ด ์ˆ˜์‹ ๊ธฐ ๊ฒฐ๊ณผ๋ฅผ ์ œ์‹œํ•œ๋‹ค. ๊ทธ ๊ฒฐ๊ณผ ์ œ์•ˆ๋œ ๋ฐฉ๋ฒ•์€ ์ „ํŒŒ ๊ฐ„์„ญ ๋ฐ ๋‹ค์ค‘๊ฒฝ๋กœ ์˜ค์ฐจ ๊ฐ์‡„์— ๊ฐ•์ธํ•˜๋ฉฐ, GPS ํ•ญ๋ฒ•์‹œ์Šคํ…œ์—์„œ์˜ ์œ„์น˜์ •ํ™•๋„ ํ–ฅ์ƒ์— ๊ฐ€๋Šฅ์„ฑ์„ ๋ณด์—ฌ์ค€๋‹ค. ๊ทธ๋กœ๋ฏ€๋กœ ์ œ์•ˆ๋œ ๋ฐฉ๋ฒ•์€ ์ฐจ๋Ÿ‰ ํ•ญ๋ฒ• ์‘์šฉ๋ถ„์•ผ์—์„œ ๋ฐฉํ•ด์‹ ํ˜ธ ๊ฐ์‡„์— ์‚ฌ์šฉ๋  ๊ฒƒ์œผ๋กœ ์˜ˆ์ƒ๋œ๋‹ค.Although hundreds of millions of receivers are used all around the world, the performance of location-based services(LBS) provided by GPS is still compromised by interference which includes unintentional distortion of correlation function due to multipath propagation. For this reason, the requirement for proper mitigation techniques becomes crucial in GPS receivers for robust, accurate, and reliable positioning. Multipath propagation can easily occur when environmental features cause combinations of reflected and diffracted replica signals to arrive at the receiving antenna. These signals which are combined with the original line-of-sight (LOS) signal can cause distortion of the receiver correlation function and ultimately distortion of the discrimination functionhence, errors in range estimation occur. Therefore, multipath error in the satellite navigation system to improve location accuracy is an important issue to be addressed. Recently, interference mitigation techniques utilizing multiple antennas have gained significant attention in GPS navigation systems. Although at the time of this dissertation, employing multiple antennas in GPS applications is mostly limited to academic research and possibly complicated military applications, it is expected that in the near future, antenna array-based receivers will also become widespread in civilian commercial markets. Rapid advances in antenna design technology and electronic systems make previously challenging problems in hardware and software easier to solve. Furthermore, due to the significant effort devoted to miniaturization of RF front-ends and antennas, the size of antenna array based receivers will no longer be a problem. Given the above, this dissertation investigates multiple antenna-based GPS the interference suppression and multipath mitigation. Firstly, a modified spatial processing technique is proposed that is capable of mitigating both high power interference and coherent and correlated GPS multipath signals. The use of spatial-temporal processing for GPS multipath mitigation is studied. A new method utilizing code carrier information based on multiple antennas is proposed to deal with highly correlated multipath components and to increase the signal to noise ratio of the beamformer by synthesizing antenna array processing. In order to verify the proposed method, a software defined GPS receiver is used. Software-based GPS signal processing technique has already produced benefits for prototyping new equipment and analyzing GPS signal quality. Not only do such receivers provide an excellent research tool for GPS algorithm verification, they also improve GPS receiver performance in a wide range of conditions. In this dissertation, the enhancement of the proposed method is presented in terms of the simulations and software defined GPS receiver using simulated IF data. From the result, the proposed method is robust to interference suppression, and multipath mitigation, and shows a strong possibility for use in improving location accuracy. Thus, this method can be employed to mitigate interference signals in vehicular navigation applications.Contents Abstract i Acknowledgements iv Contents v List of Figures x List of Tables xiv Chapter 1.Introduction 1 1.1 Introduction 1 1.2 Background and Motivation 2 1.2.1 Strong Narrowband and Wideband Interference 6 1.2.2 Multipath 7 1.3 Antenna Array Processing in GPS 11 1.3.1 Interference Suppression 11 1.3.2 Multipath Mitigation 13 1.4 Software-Defined GPS Receiver 15 1.5 Objective and Contribution 17 1.6 Dissertation Outline 18 Chapter 2. Global Positioning System 21 2.1 GPS System Overview 21 2.2 Basic Concept of GSP 25 2.3 Determining Satellite to User 28 2.4 Calculation of User Position 33 2.5 GPS Error Sources 40 2.5.1 Receiver Clock Bias 41 2.5.2 Satellite Clock Bias 42 2.5.3 Atmospheric Delay 43 2.5.4 Ephemeris Delay 46 2.5.5 Multipath Error 47 2.5.6 Receiver Noise 55 2.6 Summary 55 Chapter 3. Antenna Array Processing and Beamforming 56 3.1 Background on Antenna Arrays and Beamformers 56 3.1.1 Signal Model 59 3.2 Conventional Optimum Beamformers 69 3.2.1 Minimum Variance Distortionless Response Beamformer 69 3.2.2 Maximum Likelihood Estimator 71 3.2.3 Maximum Signal to Noise Interference Ratio Beamformer 72 3.2.4 Minimum Power Distortionless Response Beamformer 75 3.2.5 Linear Constrained Minimum Variance and Linear Constrained Minimum Power Beamformers 76 3.2.6 Eigenvector Beamformer 77 3.3 Space-Time Processing 81 3.4 Array Calibration 85 3.5 Summary 86 Chapter 4. Multipath Mitigation using Code-Carrier Information 87 4.1 Introduction 87 4.2 Interference Suppression and Multipath Mitigation 88 4.2.1 Signal Model 88 4.2.2 Interference Suppression by Subspace Projection 90 4.2.3 Multipath Mitigation by Subspace Projection 93 4.3 Determination of Multipath Satellites using Code-carrier Information 95 4.4 MSR Beamformer 100 4.5 Simulation Results 102 4.5.1 Subspace Projection and Beamforming 102 4.5.2 Performance Comparison 109 4.6 Summary 111 Chapter 5. Performance Verification using Software-Defined GPS Receiver 113 5.1 Introduction 113 5.2 Software-Defined GPS Receiver Methodology 114 5.2.1 Software-Defined GPS Receiver Signals 115 5.2.2 Software-Defined GPS Receiver Modules 116 5.3 Architecture of Software-Defined GPS Receiver 120 5.3.1 GPS Signal Generation 120 5.3.2 Interference Signal Generation 124 5.3.1 Front-End Signal Processing 125 5.4 Experimental Results 126 5.3.1 Static Environments 128 5.3.2 Dynamic Environments 133 5.5 Summary 136 Chapter 6. Conclusions and Future Work 138 6.1 Conclusions 138 6.2 Future Work 139 Bibliography 142 Appendix 168 Abstract in Korean 170 Acknowledgments 173Docto

    Acoustic event detection and localization using distributed microphone arrays

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    Automatic acoustic scene analysis is a complex task that involves several functionalities: detection (time), localization (space), separation, recognition, etc. This thesis focuses on both acoustic event detection (AED) and acoustic source localization (ASL), when several sources may be simultaneously present in a room. In particular, the experimentation work is carried out with a meeting-room scenario. Unlike previous works that either employed models of all possible sound combinations or additionally used video signals, in this thesis, the time overlapping sound problem is tackled by exploiting the signal diversity that results from the usage of multiple microphone array beamformers. The core of this thesis work is a rather computationally efficient approach that consists of three processing stages. In the first, a set of (null) steering beamformers is used to carry out diverse partial signal separations, by using multiple arbitrarily located linear microphone arrays, each of them composed of a small number of microphones. In the second stage, each of the beamformer output goes through a classification step, which uses models for all the targeted sound classes (HMM-GMM, in the experiments). Then, in a third stage, the classifier scores, either being intra- or inter-array, are combined using a probabilistic criterion (like MAP) or a machine learning fusion technique (fuzzy integral (FI), in the experiments). The above-mentioned processing scheme is applied in this thesis to a set of complexity-increasing problems, which are defined by the assumptions made regarding identities (plus time endpoints) and/or positions of sounds. In fact, the thesis report starts with the problem of unambiguously mapping the identities to the positions, continues with AED (positions assumed) and ASL (identities assumed), and ends with the integration of AED and ASL in a single system, which does not need any assumption about identities or positions. The evaluation experiments are carried out in a meeting-room scenario, where two sources are temporally overlapped; one of them is always speech and the other is an acoustic event from a pre-defined set. Two different databases are used, one that is produced by merging signals actually recorded in the UPCยฟs department smart-room, and the other consists of overlapping sound signals directly recorded in the same room and in a rather spontaneous way. From the experimental results with a single array, it can be observed that the proposed detection system performs better than either the model based system or a blind source separation based system. Moreover, the product rule based combination and the FI based fusion of the scores resulting from the multiple arrays improve the accuracies further. On the other hand, the posterior position assignment is performed with a very small error rate. Regarding ASL and assuming an accurate AED system output, the 1-source localization performance of the proposed system is slightly better than that of the widely-used SRP-PHAT system, working in an event-based mode, and it even performs significantly better than the latter one in the more complex 2-source scenario. Finally, though the joint system suffers from a slight degradation in terms of classification accuracy with respect to the case where the source positions are known, it shows the advantage of carrying out the two tasks, recognition and localization, with a single system, and it allows the inclusion of information about the prior probabilities of the source positions. It is worth noticing also that, although the acoustic scenario used for experimentation is rather limited, the approach and its formalism were developed for a general case, where the number and identities of sources are not constrained

    Cooperative Radio Communications for Green Smart Environments

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    The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: โ€ข Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsโ€ข Measurements, characterization, and modelling of radio channels beyond 4G networksโ€ข Key issues in Vehicle (V2X) communicationโ€ข Wireless Body Area Networks, including specific Radio Channel Models for WBANsโ€ข Energy efficiency and resource management enhancements in Radio Access Networksโ€ข Definitions and models for the virtualised and cloud RAN architecturesโ€ข Advances on feasible indoor localization and tracking techniquesโ€ข Recent findings and innovations in antenna systems for communicationsโ€ข Physical Layer Network Coding for next generation wireless systemsโ€ข Methods and techniques for MIMO Over the Air (OTA) testin

    Cooperative Radio Communications for Green Smart Environments

    Get PDF
    The demand for mobile connectivity is continuously increasing, and by 2020 Mobile and Wireless Communications will serve not only very dense populations of mobile phones and nomadic computers, but also the expected multiplicity of devices and sensors located in machines, vehicles, health systems and city infrastructures. Future Mobile Networks are then faced with many new scenarios and use cases, which will load the networks with different data traffic patterns, in new or shared spectrum bands, creating new specific requirements. This book addresses both the techniques to model, analyse and optimise the radio links and transmission systems in such scenarios, together with the most advanced radio access, resource management and mobile networking technologies. This text summarises the work performed by more than 500 researchers from more than 120 institutions in Europe, America and Asia, from both academia and industries, within the framework of the COST IC1004 Action on "Cooperative Radio Communications for Green and Smart Environments". The book will have appeal to graduates and researchers in the Radio Communications area, and also to engineers working in the Wireless industry. Topics discussed in this book include: โ€ข Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environmentsโ€ข Measurements, characterization, and modelling of radio channels beyond 4G networksโ€ข Key issues in Vehicle (V2X) communicationโ€ข Wireless Body Area Networks, including specific Radio Channel Models for WBANsโ€ข Energy efficiency and resource management enhancements in Radio Access Networksโ€ข Definitions and models for the virtualised and cloud RAN architecturesโ€ข Advances on feasible indoor localization and tracking techniquesโ€ข Recent findings and innovations in antenna systems for communicationsโ€ข Physical Layer Network Coding for next generation wireless systemsโ€ข Methods and techniques for MIMO Over the Air (OTA) testin

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    Antenna Systems

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    Ambient acoustics as indicator of environmental change in the Beaufort Sea: experiments & methods for analysis

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    Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy at the Massachusetts Institute of Technology and the Woods Hole Oceanographic Institution June 2021.The Arctic Ocean is a vital component of Earthโ€™s climate system experiencing dramatic environmental changes. The changes are reflected in its underwater ambient soundscape as its origin and propagation are primarily dependent on properties of the ice cover and water column. The first component of this work examines the effect on ambient noise characteristics due to changes to the Beaufort Sea sound speed profile (SSP) and ice cover. Specifically, the emergence of a warm water intrusion near 70 m depth has altered the historical Arctic SSP while the ice cover has become thinner and younger due to the rise in average global temperature. Hypothesized shifts to the ambient soundscape and surface noise generation due to these changes are verified by comparing the measured noise data during two experiments to modeled results. These changes include a broadside notch in noise vertical directionality as well as a shift from uniform surface noise generation to discrete generation at specific ranges. Motivated by our data analyses, the second component presents several tools to facilitate ambient noise characterization and generation monitoring. One is a convolutional neural network (CNN) approach to noise range estimation. Its robustness to SSP and bottom depth mismatch is compared with conventional matched field processing. We further explore how the CNN approach achieves its performance by examining its intermediate outputs. Another tool is a frequency domain, transient event detection algorithm that leverages image processing and hierarchical clustering to identify and categorize noise transients in data spectrograms. The spectral content retained by this method enables insight into the generation mechanism of the detected events by the ice cover. Lastly, we present the deployment of a seismo-acoustic system to localize transient events. Two forward approaches that utilize time-difference-ofarrival are described and compared with a more conventional, inverse technique. The examination of this systemโ€™s performance prompts recommendations for future deployments. With our ambient noise analysis and algorithm development, we hope these contributions provide a stronger foundation for continued study of the Arctic ambient soundscape as the region continues to grow in significance.Office of Naval Research (ONR) via the University of California - San Diego (UCSD) under award number N00014-16-1-2129. Defense Advanced Research Projects Agency (DARPA) via Applied Physical Sciences Corp. (APS) under award number HR0011-18-C-0008. Office of Naval Research (ONR) under award number N00014-17-1-2474. Office of Naval Research (ONR) under award number N00014-19-1-2741. National Science Foundation (NSF) under grant number 2389237

    Danish activities concerning noise in the environment (A)

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