1,291 research outputs found

    UHF propagation channel characterization for tunnel microcellular and personal communications.

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    by Yue Ping Zhang.Publication date from spine.Thesis (Ph.D.)--Chinese University of Hong Kong, 1995.Includes bibliographical references (leaves 194-200).DEDICATIONACKNOWLEDGMENTSChapterChapter 1. --- Introduction --- p.1Chapter 1.1 --- Brief Description of Tunnels --- p.1Chapter 1.2 --- Review of Tunnel Imperfect Waveguide Models --- p.2Chapter 1.3 --- Review of Tunnel Geometrical Optical Model --- p.4Chapter 1.4 --- Review of Tunnel Propagation Experimental Results --- p.6Chapter 1.5 --- Review of Existing Tunnel UHF Radio Communication Systems --- p.13Chapter 1.6 --- Statement of Problems to be Studied --- p.15Chapter 1.7 --- Organization --- p.15Chapter 2 --- Propagation in Empty Tunnels --- p.18Chapter 2.1 --- Introduction --- p.18Chapter 2.2 --- Propagation in Empty Tunnels --- p.18Chapter 2.2.1 --- The Imperfect Empty Straight Rectangular Waveguide Model --- p.19Chapter 2.2.2 --- The Hertz Vectors for Empty Straight Tunnels --- p.20Chapter 2.2.3 --- The Propagation Modal Equations for Empty Straight Tunnels --- p.23Chapter 2.2.4 --- The Propagation Characteristics of Empty Straight Tunnels --- p.26Chapter 2.2.5 --- Propagation Numerical Results in Empty Straight Tunnels --- p.30Chapter 2.3 --- Propagation in Empty Curved Tunnels --- p.36Chapter 2.3.1 --- The Imperfect Empty Curved Rectangular Waveguide Model --- p.37Chapter 2.3.2 --- The Hertz Vectors for Empty Curved Tunnels --- p.39Chapter 2.3.3 --- The Propagation Modal Equations for Empty Curved Tunnels --- p.41Chapter 2.3.4 --- The Propagation Characteristics of Empty Curved Tunnels --- p.43Chapter 2.2.5 --- Propagation Numerical Results in Empty Curved Tunnels --- p.47Chapter 2.4 --- Summary --- p.50Chapter 3 --- Propagation in Occupied Tunnels --- p.53Chapter 3.1 --- Introduction --- p.53Chapter 3.2 --- Propagation in Road Tunnels --- p.53Chapter 3.2.1 --- The Imperfect Partially Filled Rectangular Waveguide Model --- p.54Chapter 3.2.2 --- The Scalar Potentials for Road tunnels --- p.56Chapter 3.2.3 --- The Propagation Modal Equations for Road Tunnels --- p.59Chapter 3.2.4 --- Propagation Numerical Results in Road Tunnels --- p.61Chapter 3.3 --- Propagation in Railway Tunnels --- p.64Chapter 3.3.1 --- The Imperfect Periodically Loaded Rectangular Waveguide Model --- p.65Chapter 3.3.2 --- The Surface Impedance Approximation --- p.66Chapter 3.3.2.1 --- The Surface Impedance of a Semi-infinite Lossy Dielectric Medium --- p.66Chapter 3.3.2.2 --- The Surface Impedance of a Thin Lossy Dielectric Slab --- p.67Chapter 3.3.2.3 --- The Surface Impedance of a Three-layered Half Space --- p.69Chapter 3.3.2.4 --- The Surface Impedance of the Sidewall of a Train in a Tunnel --- p.70Chapter 3.3.3 --- The Hertz Vectors for Railway Tunnels --- p.71Chapter 3.3.4 --- The Propagation Modal Equations for Railway Tunnels --- p.73Chapter 3.3.5 --- The Propagation Characteristics of Railway Tunnels --- p.76Chapter 3.3.6 --- Propagation Numerical Results in Railway Tunnels --- p.78Chapter 3.4 --- Propagation in Mine Tunnels --- p.84Chapter 3.4.1 --- The Imperfect periodically Loaded Rectangular Waveguide Model --- p.85Chapter 3.4.2 --- The Hertz Vectors for Mine Tunnels --- p.86Chapter 3.4.3 --- The Propagation modal Equations for Mine Tunnels --- p.88Chapter 3.4.4 --- The Propagation Characteristics of Mine Tunnels --- p.95Chapter 3.4.5 --- Propagation Numerical Results in Mine Tunnels --- p.96Chapter 3.5 --- Summary --- p.97Chapter 4 --- Statistical and Deterministic Models of Tunnel UHF Propagation --- p.100Chapter 4.1 --- Introduction --- p.100Chapter 4.2 --- Statistical Model of Tunnel UHF Propagation --- p.100Chapter 4.2.1 --- Experiments --- p.101Chapter 4.2.1.1 --- Experimental Set-ups --- p.102Chapter 4.2.1.2 --- Experimental Tunnels --- p.104Chapter 4.2.1.3 --- Experimental Techniques --- p.106Chapter 4.2.2 --- Statistical Parameters --- p.109Chapter 4.2.2.1 --- Parameters to Characterize Narrow Band Radio Propagation Channels --- p.109Chapter 4.2.2.2 --- Parameters to Characterize Wide Band Radio Propagation Channels --- p.111Chapter 4.2.3 --- Propagation Statistical Results and Discussion --- p.112Chapter 4.2.3.1 --- Tunnel Narrow Band Radio Propagation Characteristics --- p.112Chapter 4.2.3.1.1 --- Power Distance Law --- p.114Chapter 4.2.3.1.2 --- The Slow Fading Statistics --- p.120Chapter 4.2.3.1.3 --- The Fast Fading Statistics --- p.122Chapter 4.2.3.2 --- Tunnel Wide Band Radio Propagation Characteristics --- p.125Chapter 4.2.3.2.1 --- RMS Delay Spread --- p.126Chapter 4.2.3.2.2 --- RMS Delay Spread Statistics --- p.130Chapter 4.3 --- Deterministic Model of Tunnel UHF Propagation --- p.132Chapter 4.3.1 --- The Tunnel Geometrical Optical Propagation Model --- p.134Chapter 4.3.2 --- The Tunnel Impedance Uniform Diffracted Propagation Model --- p.141Chapter 4.3.2.1 --- Determination of Diffraction Points --- p.146Chapter 4.3.2.2 --- Diffraction Coefficients for Impedance Wedges --- p.147Chapter 4.3.3 --- Comparison with Measurements --- p.151Chapter 4.3.3.1 --- Narrow Band Comparison of Simulated and Measured Results --- p.151Chapter 4.3.3.1.1 --- Narrow Band Propagation in Empty Straight Tunnels --- p.151Chapter 4.3.3.1.2 --- Narrow Band Propagation in Curved or Obstructed Tunnels --- p.154Chapter 4.3.3.2 --- Wide Band Comparison of Simulated and Measured Results --- p.158Chapter 4.3.3.2.1 --- Wide Band Propagation in Empty Straight Tunnels --- p.159Chapter 4.3.3.2.2 --- Wide Band Propagation in an Obstructed Tunnel --- p.163Chapter 4.4 --- Summary --- p.165Chapter 5 --- Propagation in Tunnel and Open Air Transition Region --- p.170Chapter 5.1 --- Introduction --- p.170Chapter 5.2 --- Radiation of Radio Waves from a Rectangular Tunnel into Open Air --- p.171Chapter 5.2.1 --- Radiation Formulation Using Equivalent Current Source Concept --- p.171Chapter 5.2.2 --- Radiation Numerical Results --- p.175Chapter 5.3 --- Propagation Characteristics of UHF Radio Waves in Cuttings --- p.177Chapter 5.3.1 --- The Attenuation Constant due to the Absorption --- p.178Chapter 5.3.2 --- The Attenuation Constant due to the Roughness of the Sidewalls --- p.182Chapter 5.3.3 --- The Attenuation Constant due to the tilts of the Sidewalls --- p.183Chapter 5.3.4 --- Propagation Numerical Results in Cuttings --- p.184Chapter 5.4 --- Summary --- p.187Chapter 6 --- Conclusion and Recommendation for Future Work --- p.189APPENDIX --- p.193The Approximate Solution of a Transcendental Equation --- p.193REFERENCES --- p.19

    Design of surface acoustic wave filters and applications in future communication systems

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    Analysis of Ultra Wide Band (UWB) Technology for an Indoor Geolocation and Physiological Monitoring System

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    The goal of this research is to analyze the utility of UWB for indoor geolocation and to evaluate a prototype system, which will send information detailing a person’s position and physiological status to a command center. In a real world environment, geolocation and physiological status information needs to be sent to a command and control center that may be located several miles away from the operational environment. This research analyzes and characterizes the UWB signal in the various operational environments associated with indoor geolocation. Additionally, typical usage scenarios for the interaction between UWB and other devices are also tested and evaluated

    INDOOR-WIRELESS LOCATION TECHNIQUES AND ALGORITHMS UTILIZING UHF RFID AND BLE TECHNOLOGIES

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    The work presented herein explores the ability of Ultra High Frequency Radio Frequency (UHF RF) devices, specifically (Radio Frequency Identification) RFID passive tags and Bluetooth Low Energy (BLE) to be used as tools to locate items of interest inside a building. Localization Systems based on these technologies are commercially available, but have failed to be widely adopted due to significant drawbacks in the accuracy and reliability of state of the art systems. It is the goal of this work to address that issue by identifying and potentially improving upon localization algorithms. The work presented here breaks the process of localization into distance estimations and trilateration algorithms to use those estimations to determine a 2D location. Distance estimations are the largest error source in trilateration. Several methods are proposed to improve speed and accuracy of measurements using additional information from frequency variations and phase angle information. Adding information from the characteristic signature of multipath signals allowed for a significant reduction in distance estimation error for both BLE and RFID which was quantified using neural network optimization techniques. The resulting error reduction algorithm was generalizable to completely new environments with very different multipath behavior and was a significant contribution of this work. Another significant contribution of this work is the experimental comparison of trilateration algorithms, which tested new and existing methods of trilateration for accuracy in a controlled environment using the same data sets. Several new or improved methods of triangulation are presented as well as traditional methods from the literature in the analysis. The Antenna Pattern Method represents a new way of compensating for the antenna radiation pattern and its potential impact on signal strength, which is also an important contribution of this effort. The performance of each algorithm for multiple types of inputs are compared and the resulting error matrix allows a potential system designer to select the best option given the particular system constraints

    Proceedings of the Fifteenth NASA Propagation Experimenters Meeting (NAPEX 15) and the Advanced Communications Technology Satellite (ACTS) Propagation Studies Miniworkshop

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    The NASA Propagation Experimenters Meeting (NAPEX), supported by the NASA Propagation Program, is convened annually to discuss studies made on radio wave propagation by investigators from domestic and international organizations. The meeting was organized into three technical sessions. The first session was dedicated to Olympus and ACTS studies and experiments, the second session was focused on the propagation studies and measurements, and the third session covered computer-based propagation model development. In total, sixteen technical papers and some informal contributions were presented. Following NAPEX 15, the Advanced Communications Technology Satellite (ACTS) miniworkshop was held on 29 Jun. 1991, to review ACTS propagation activities, with emphasis on ACTS hardware development and experiment planning. Five papers were presented

    Ubiquitous Indoor Fine-Grained Positioning and Tracking: A Channel Response Perspective

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    The future of location-aided applications is shaped by the ubiquity of Internet-of-Things devices. As an increasing amount of commercial off-the-shelf radio devices support channel response collection, it is possible to achieve fine-grained position estimation at a relatively low cost. In this paper, we focus on the channel response-based positioning and tracking for various applications. We first give an overview of the state of the art (SOTA) of channel response-enabled localization, which is further classified into two categories, i.e., device-based and contact-free schemes. A taxonomy for these complementary approaches is provided concerning the involved techniques. Then, we present a micro-benchmark of channel response-based direct positioning and tracking for both device-based and contact-free schemes. Finally, some practical issues for real-world applications and future research opportunities are pointed out.Comment: 13th International Conference on Indoor Positioning and Indoor Navigatio

    ATS-6 engineering performance report. Volume 3: Telecommunications and power

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    Functional design requirements and in-orbit operations, performance, and anomalies are discussed for (1) the communications subsystem, (2) the electrical power system, and (3) the telemetry and command subsystem. The latter includes a review of ground support. Tracking and data relay experiments and the Apollo-Soyuz test program are reviewed
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