102 research outputs found

    Naval Postgraduate School Academic Catalog - February 2023

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    Analog Radio-over-Fiber for 5G/6G Millimeter-Wave Communications

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    Indoor Positioning and Navigation

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    In recent years, rapid development in robotics, mobile, and communication technologies has encouraged many studies in the field of localization and navigation in indoor environments. An accurate localization system that can operate in an indoor environment has considerable practical value, because it can be built into autonomous mobile systems or a personal navigation system on a smartphone for guiding people through airports, shopping malls, museums and other public institutions, etc. Such a system would be particularly useful for blind people. Modern smartphones are equipped with numerous sensors (such as inertial sensors, cameras, and barometers) and communication modules (such as WiFi, Bluetooth, NFC, LTE/5G, and UWB capabilities), which enable the implementation of various localization algorithms, namely, visual localization, inertial navigation system, and radio localization. For the mapping of indoor environments and localization of autonomous mobile sysems, LIDAR sensors are also frequently used in addition to smartphone sensors. Visual localization and inertial navigation systems are sensitive to external disturbances; therefore, sensor fusion approaches can be used for the implementation of robust localization algorithms. These have to be optimized in order to be computationally efficient, which is essential for real-time processing and low energy consumption on a smartphone or robot

    2010-2011, University of Memphis bulletin

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    University of Memphis bulletin containing the graduate catalog for 2010-2011.https://digitalcommons.memphis.edu/speccoll-ua-pub-bulletins/1430/thumbnail.jp

    Naval Postgraduate School Academic Catalog - September 2022

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    Resilient Peer-to-Peer Ranging using Narrowband High-Performance Software-Defined Radios for Mission-Critical Applications

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    There has been a growing need for resilient positioning for numerous applications of the military and emergency services that routinely conduct operations that require an uninterrupted positioning service. However, the level of resilience required for these applications is difficult to achieve using the popular navigation and positioning systems available at the time of this writing. Most of these systems are dependent on existing infrastructure to function or have certain vulnerabilities that can be too easily exploited by hostile forces. Mobile ad-hoc networks can bypass some of these prevalent issues making them an auspicious topic for positioning and navigation research and development. Such networks consist of portable devices that collaborate to form wireless communication links with one another and collectively carry out vital network functions independent of any fixed centralized infrastructure. The purpose of the research presented in this thesis is to adapt the protocols of an existing narrowband mobile ad-hoc communications system provided by Terrafix to enable range measuring for positioning. This is done by extracting transmission and reception timestamps of signals exchanged between neighbouring radios in the network with the highest precision possible. However, many aspects of the radios forming this network are generally not conducive to precise ranging, so the ranging protocols implemented need to either maneuver around these shortcomings or compensate for loss of precision caused. In particular, the narrow bandwidth of the signals that drastically reduces the resolution of symbol timing. The objective is to determine what level of accuracy and precision is possible using this radio network and whether one can justify investment for further development. Early experiments have provided a simple ranging demonstration in a benign environment, using the existing synchronization protocols, by extracting time data. The experiments have then advanced to the radio’s signal processing to adjust the synchronization protocols for maximize symbol timing precision and correct for clock drift. By implementing innovative synchronization techniques to the radio network, ranging data collected under benign conditions can exhibit a standard deviation of less than 3m. The lowest standard deviation achieved using only the existing methods of synchronization was over two orders of magnitude greater. All this is achieved in spite of the very narrow 10−20kHz bandwidth of the radio signals, which makes producing range estimates with an error less than 10−100m much more challenging compared to wider bandwidth systems. However, this figure is beholden to the relative motion of neighbouring radios in the network and how frequently range estimates need to be made. This thesis demonstrates how such a precision may be obtained and how this figure is likely to hold up when applied in conditions that are not ideal

    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: • Radio waves propagation phenomena in diverse urban, indoor, vehicular and body environments• Measurements, characterization, and modelling of radio channels beyond 4G networks• Key issues in Vehicle (V2X) communication• Wireless Body Area Networks, including specific Radio Channel Models for WBANs• Energy efficiency and resource management enhancements in Radio Access Networks• Definitions and models for the virtualised and cloud RAN architectures• Advances on feasible indoor localization and tracking techniques• Recent findings and innovations in antenna systems for communications• Physical Layer Network Coding for next generation wireless systems• Methods and techniques for MIMO Over the Air (OTA) testin

    Naval Postgraduate School Academic Catalog - 09 July 2021

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    Recent Advances in Wireless Communications and Networks

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    This book focuses on the current hottest issues from the lowest layers to the upper layers of wireless communication networks and provides "real-time" research progress on these issues. The authors have made every effort to systematically organize the information on these topics to make it easily accessible to readers of any level. This book also maintains the balance between current research results and their theoretical support. In this book, a variety of novel techniques in wireless communications and networks are investigated. The authors attempt to present these topics in detail. Insightful and reader-friendly descriptions are presented to nourish readers of any level, from practicing and knowledgeable communication engineers to beginning or professional researchers. All interested readers can easily find noteworthy materials in much greater detail than in previous publications and in the references cited in these chapters

    Radio Communications

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    In the last decades the restless evolution of information and communication technologies (ICT) brought to a deep transformation of our habits. The growth of the Internet and the advances in hardware and software implementations modied our way to communicate and to share information. In this book, an overview of the major issues faced today by researchers in the eld of radio communications is given through 35 high quality chapters written by specialists working in universities and research centers all over the world. Various aspects will be deeply discussed: channel modeling, beamforming, multiple antennas, cooperative networks, opportunistic scheduling, advanced admission control, handover management, systems performance assessment, routing issues in mobility conditions, localization, web security. Advanced techniques for the radio resource management will be discussed both in single and multiple radio technologies; either in infrastructure, mesh or ad hoc networks
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