Academic literature on the topic 'MICROCELLULAR PROPAGATION'

La propagation des ondes radio electriques est etudiee en milieu urbain quand l'antenne d'emission est sous le niveau des toits. Les caracteristiques principales du signal radio et les methodes de calcul du champ electromagnetique sont etudies. Les mecanismes qui gouvernent la propagation des ondes dans ce contexte sont analyses a l'aide de la theorie des rayons et de la theorie uniforme de la diffraction. Les resultats qui decoulent de cette etude sont utilises dans la mise en uvre d'un outil de prediction de l'affaiblissement et de couverture radio. L'ensemble des resultats est valide experimentalement par comparaison a des mesures

Th. doct.--Électron. et communications--Paris--ENST, 1995.<br>Thèse délivrée en association avec l'Université de Paris 6. Annexes en français et en anglais. Notes bibliogr. Résumés en français et en anglais.

A comparative analysis of time-domain (TD) solution, based on an established UTD diffraction model, are presented for modeling of Ultra-wideband (UWB) signal for lossy dielectric obstacles which gives accurate result to any arbitrary position of transmitter and receiver in a complex channel environment. Obstacles considered in the work include dielectric Wedge with homogenous, isotropic, low-loss dielectric characteristics. Different UTD-TD Diffraction Coefficients are proposed and compared with the IFFT of rigorous (i.e., Maliuzhinets) diffraction coefficient (RDC). The proposed work provides an in-depth analysis of the UTD model and presents an accurate and computationally more efficient TD solution for the available UTD diffraction coefficients for lossy dielectric medium, for both soft and hard polarizations. Moreover the reciprocity and symmetry for the diffraction coefficient in the time-domain have been proven for different position of transmitter and receiver. The time-domain modeling for transmission and reflection of UWB signals for 2-D & 3-D multi-modeled obstacle is also done. The obstacle is called multi-modeled since the obstacle consists of two entirely different structure i.e. dielectric wedge followed by dielectric slab. The comparison between the TD solution and the numerical inverse fast Fourier transform of the FD (IFFT-FD) solution proves the accuracy of the proposed solution. The significant gain in the computational speed achieved through the proposed TD solution is demonstrated by comparing its computation time with that of the exact IFFT-FD solution.

博士<br>國立交通大學<br>電子工程系<br>87<br>This thesis presents a site-specific and a statistically scattering models to investigate the characteristics of UHF radio propagation in microcellular urban environments. First, a novel 3-D site-specific scattering model is developed to evaluate the average path loss of a microcellular radio channel in an urban environment. The analytical scattering model combined with a patched-wall model predicts the median path loss more accurately than the conventional analytical ray-tracing model in the cases studied. Comparing the path loss with the measured one at 1.8-GHz demonstrates the effectiveness of the scattering model. The scattering model includes three major propagation modes: (1) a direct-path wave; (2) a ground-reflected wave; and (3) the scattered field from the walls aligned along a street. The proposed model, with a polarization scattering matrix associated with the patched-wall model, aptly describes the third mode, which is usually neglected or oversimplified. Second, an analytical hybrid scattering model, combining a site-specific scattering model and a statistically scattering model, is developed to evaluate the statistical characteristics of received power for microcellular radio channel. The former model yields a deterministic prediction of the received power. The later model describes the scattered field due to the randomly positioned scatterers around the receiver. From this study, it is found that the randomly scattered field gives a significant effect on localized fading distribution. The mean power of the randomly scattered field is linearly dependent on logarithm of propagation distance and the decay factors at three different sites are similar. From the simulation results, it is also found that changing transmitting antenna height may yield a significant effect on the small-scale fading characteristics. However, varying the patch size or street width may have little effect on the fading distribution. In addition, a model of the random distribution of the Rician factor is suggested from the measurement of 1.8 GHz radio propagation in outdoor urban microcells. It is found that the probability density function (pdf) of the Rician factor for low tier systems in urban environments follows a lognormal distribution.

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

碩士<br>國立交通大學<br>電信工程研究所<br>86<br>Mechanism of UHF radiowave propagation into multistory office buildings is explored by using ray-tracing based models, which include a three-dimensional (3-D) ray-tracing model and a direct-transmitted ray (DTR) model. Prediction accuracy of the models is ascertained by the measured data and the measurements are carried out at many specific sites with different propagation scenario. Their measured results also demonstrate some important propagation phenomena. It is found that (1) the direct transmitted wave may be the dominant mode; (2) the path loss neither increases nor decreases monotonically as a function of increasing floor level; and (3) there is not much difference of the average path loss among the receiving positions in the same room.