Safety Relevant Positioning Applications in Rail Traffic using the European Satellite System "Galileo"

Die Ortung im Eisenbahnverkehr hat eine hohe sicherheitstechnische Relevanz. Eine falsch detektierte Position eines Fahrzeugs kann zu einer erheblichen Gefährdung führen, da die ermittelte Ortsinformation für die Freigabe und das Wiederbesetzen von Gleisabschnitten genutzt wird. Daraus abgeleitet, müssen Ortungssysteme bei der Zulassung unter anderem die folgenden sicherheitskritischen Anforderungen erfüllen Genauigkeit, Zuverlässigkeit, Integrität und Verfügbarkeit der Ortungsinformation, die gemäß SIL 4 nachzuweisen sind

Measurements and analysis of large-scale fading characteristics in curved subway tunnels at 920 MHz, 2400 MHz, and 5705 MHz

ave propagation characteristics in curved tunnels are of importance for designing reliable communications in subway systems. This paper presents the extensive propagation measurements conducted in two typical types of subway tunnels—traditional arched “Type I” tunnel and modern arched “Type II” tunnel—with300- and 500-m radii of curvature with different configurations—horizontal and vertical polarizations at 920, 2400, and 5705 MHz, respectively. Based on the measurements, statistical metrics of propagation loss and shadow fading (path-loss exponent, shadow fading distribution, autocorrelation, and cross-correlation) in all the measurement cases are extracted. Then, the large-scale fading characteristics in the curved subway tunnels are compared with the cases of road and railway tunnels, the other main rail traffic scenarios, and some “typical” scenarios to give a comprehensive insight into the propagation in various scenarios where the intelligent transportation systems are deployed. Moreover, for each of the large-scale fading parameters, extensive analysis and discussions are made to reflect the physical laws behind the observations. The quantitative results and findings are useful to realize intelligent transportation systems in the subway system

Propagation Mechanism modeling in the Near-Region of Arbitrary Cross-Sectional Tunnels.

Along with the increase of the use of working frequencies in advanced radio communication systems, the near-region inside tunnels lengthens considerably and even occupies the whole propagation cell or the entire length of some short tunnels. This paper analytically models the propagation mechanisms and their dividing point in the near-region of arbitrary cross-sectional tunnels for the first time. To begin with, the propagation losses owing to the free space mechanism and the multimode waveguide mechanism are modeled, respectively. Then, by conjunctively employing the propagation theory and the three-dimensional solid geometry, the paper presents a general model for the dividing point between two propagation mechanisms. It is worthy to mention that this model can be applied in arbitrary cross-sectional tunnels. Furthermore, the general dividing point model is specified in rectangular, circular, and arched tunnels, respectively. Five groups of measurements are used to justify the model in different tunnels at different frequencies. Finally, in order to facilitate the use of the model, simplified analytical solutions for the dividing point in five specific application situations are derived. The results in this paper could help deepen the insight into the propagation mechanisms in tunnels

Aeronautical Engineering. A continuing bibliography with indexes, supplement 156

This bibliography lists 288 reports, articles and other documents introduced into the NASA scientific and technical information system in December 1982

Robot Localization in Tunnels: Combining Discrete Features in a Pose Graph Framework; 35214292

Robot localization inside tunnels is a challenging task due to the special conditions of these environments. The GPS-denied nature of these scenarios, coupled with the low visibility, slippery and irregular surfaces, and lack of distinguishable visual and structural features, make traditional robotics methods based on cameras, lasers, or wheel encoders unreliable. Fortunately, tunnels provide other types of valuable information that can be used for localization purposes. On the one hand, radio frequency signal propagation in these types of scenarios shows a predictable periodic structure (periodic fadings) under certain settings, and on the other hand, tunnels present structural characteristics (e.g., galleries, emergency shelters) that must comply with safety regulations. The solution presented in this paper consists of detecting both types of features to be introduced as discrete sources of information in an alternative graph-based localization approach. The results obtained from experiments conducted in a real tunnel demonstrate the validity and suitability of the proposed system for inspection applications. © 2022 by the authors. Licensee MDPI, Basel, Switzerland

An analysis of communication and navigation issues in collision avoidance support systems

Collision avoidance support systems (CASS) are nowadays one of the main fields of interest in the area of road transportation. Among the different approaches, those systems based on vehicle cooperation to avoid collisions present the most promising perspectives. Works available in the current literature have in common that the performance of such solutions strongly relies on the operation of two on-board subsystems: navigation and communications. However, the performance of these two subsystems is usually underestimated when the whole solution is evaluated. Collision avoidance support applications can be considered among the most critical vehicular services, and this is the reason why this paper focuses on the performance issues of these two subsystems. Main issues regarding navigation and communication performance are discussed along the paper, and a study of the literature in the field is completed with the evaluation of different system prototypes. Communication and navigation tests in real environments yield further conclusions discussed in the paper.The Authors would like to thank the Spanish Ministerio de Fomento and the Ministerio de Ciencia e Innovacion for sponsoring these research activities under the grants FOM/2454/2007, TIN2008-06441-C02-02 and AP2005-1437. Last one in frames of the FPU program. This work has been carried out inside the Intelligent Systems group of the University of Murcia, awarded as an excellence researching group in frames of the Spanish Plan de Ciencia y Tecnologıa de la Region de Murcia (04552/GERM/06)

UHF propagation channel characterization for tunnel microcellular and personal communications.

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

Broadcasting with Prediction and Selective Forwarding in Vehicular Networks

Broadcasting in vehicular networks has attracted great interest in research community and industry. Broadcasting on disseminating information to individual vehicle beyond the transmission range is based on inter-vehicle communication systems. It is crucial to broadcast messages to other vehicles as fast as possible because the messages in vehicle communication systems are often emergency messages such as accident warning or alarm. In many current approaches, the message initiator or sender selects the node among its neighbors that is farthest away from it in the broadcasting direction and then assigns the node to rebroadcast the message once the node gets out of its range or after a particular time slot. However, this approach may select a nonoptimal candidate because it does not consider the moving status of vehicles including their moving directions and speeds. In this paper, we develop a new approach based on prediction of future velocity and selective forwarding. The current message sender selects the best candidate that will rebroadcast the message to other vehicles as fast as possible. Key to the decision making is to consider the candidates\u27 previous moving status and predict the future moving trends of the candidates so that the message is spread out faster. In addition, this approach generates very low overhead. Simulations demonstrate that our approach significantly decreases end-to-end delay and improves message delivery ratio