D.J. Cichon

Concepts and results for 3D digital terrain-based wave propagation models: an overview

Mobile communication links are severely influenced by propagation effects. Wave propagation in the VHF/UHF frequency range over natural and man-made terrain is strongly dependent on topography and morphography. Propagation modeling is based on a ray-optical approach. Wave interactions, like diffraction and scattering, over the propagation path are described by the uniform theory of diffraction (UTD) and physical optics (PO). Propagation models for rural and urban areas are presented for 2-D and 3-D ray tracing. Near-range models apply to the corresponding areas in forest and urban sites. The field-strength delay spectrum describes ray contributions with deterministic amplitudes but statistical phases are used to derive time-and frequency-domain channel characteristics. Comparisons between measured and predicted data are presented. >

Ray optical modeling of wireless communications in high-speed railway tunnels

A new deterministic approach for wave propagation modeling in high-speed train tunnels is presented. The model is based on a new ray launching method and results in the polarimetric and complex channel impulse response as well as the Doppler diagram for radio links between on-train stations and tunnel-fixed stations. Different channel simulations under certain propagation conditions are presented.

Ray optical prediction of outdoor and indoor coverage in urban macro- and micro-cells

A new approach for the prediction of path loss and channel impulse response of radio links with building penetration is presented. The wave propagation prediction is based on ray-tracing algorithms implemented in the IHE-URBAN-MICRO model, which has already been successfully applied to urban micro- and macro-cells. A brief description of this model is given and comparisons with path loss measurements are shown. The extension of the IHE-URBAN-MICRO model for indoor receiver locations, resulting in the new model IHE-URBAN-MICRO-I, is presented. Both models use vector oriented building data and raster based topography data. Arbitrary outdoor base station heights can be handled by the models, which is a very important feature from a practical point of view.

Ray optical indoor modeling in multi-floored buildings: simulations and measurements

The paper presents a deterministic approach for UHF/EHF indoor and outdoor propagation modeling in picocells. The approach takes into account multiple reflected and multiple wall-penetrated ray paths. Building walls are modeled as multilayered media with different material parameters. For microcells and picocells the important issue of building penetration from outdoors to indoors call be regarded as well as indoor propagation. This modeling approach results in an area covering prediction of path loss in multi-floored buildings. The channel impulse response in magnitude, phase, delay, angle-of-departure, and angle-of-arrival is obtained for arbitrary selected receive locations. 3D-simulation results are presented and compared with measurements in a multi-floored building.

Modellierung der Wellenausbreitung in urbanem Gelände

An efficient planning method for radio communication systems requires a well known wave propagation in the considered area. Thus a new ray-optical model for the UHF wave propagation in urban areas is developed at the Institut für Höchstfrequenztechnik und Elektronik (University of Karlsruhe). This 3D model provides a polarimetric and complex fieldstrength prediction. Additionally it gives the possibility to characterise a radio channel based on a statistical analysis of multipath signals. A comparison between measurements and model predicted pathless in a real urban area is given. Furthermore the possibilities of additional information extraction are discussed. Für die Dokumentation: Urbanes Wellenausbreitungsmodell / Mehrwegeausbreitung / Polarimetrische Feldstärkevorhersage / Zellulare Mobilfunknetze

Determination of time-variant radio links in high-speed train tunnels by ray optical modeling

A new deterministic approach for wave propagation modeling in high-speed train tunnels is presented. The model is based on a new ray launching method and results in the polarimetric and complex channel impulse response as well as the Doppler diagram for radio links between on-train stations and tunnel-fixed stations. Different channel simulations under certain propagation conditions are presented.

Verification of deterministic wave propagation models for rural and urban areas

A detailed comparison of measurements and field-strength predictions in the UHF frequency range gained from 3D wave propagation models for both rural and urban areas is presented. Specifically, the authors investigated the performance of novel UTD (uniform theory of diffraction) models in both typical rural and urban areas concerning microcell and macrocell transmitter networks. The necessity of high-quality morphological and topographical data and the importance of 3D propagation analysis was demonstrated. However, even with a lower resolution of the database, good agreement in prediction of mean field strength level and probability density function is shown. The consideration of multipath propagation as well as a more accurate description of diffraction and refraction effects leads to better predictions compared with results gained from empirical or semi-empirical models.<<ETX>>

New planning methods for single frequency networks

For analog broadcast networks the planning parameters for frequency, power and site assignment are well known, for digital audio broadcast networks the research into these criteria just started. This paper presents the derivation of protection ratios and fieldstrength levels under worst case conditions for digital audio broadcast systems from the bit error rate of the unprotected propagation channel. This channel is modeled ray optically as a 3D wave propagation channel, based on digital terrain data. Different terrain types, frequencies and temporal/spatial probabilities are considered.

Ray optical wave propagation models for the characterization of radio channels in urban outdoor and indoor environments

A deterministic approach for the prediction of path loss and channel impulse response of UHF radio links in built-up areas, including building penetrating links, is presented. The wave propagation prediction is based on ray-tracing algorithms implemented in the URBAN-MICRO model. A brief description of this model is given and comparisons with path loss measurements are shown. Further an extension of the URBAN-MICRO model for in-building antenna locations, resulting in the new model URBAN-MICRO-I, is presented. Both models use vector oriented building data and raster based topography data. Arbitrary outdoor base station heights can be handled by the models, which is a very important feature from a practical point of view.

Influence of the receiver near range in urban and forested areas in land mobile radio systems

Network planning in mobile communications requires a realistic description of the propagation phenomena. Common wave propagation models for rural areas consider mainly the influence of topography. However, shadowing effects of the morphography in the vicinity of the mobile cause additional path loss. Usually this path loss is accounted for either by empirical corrections or by additional knife edges. In this paper new ray optical approaches for the calculation of the additional path loss for mobile locations within forested or urban environments are presented. For these situations typical macro situations are defined. In the case of urban environments the additional path loss is determined by means of the Uniform Theory of Diffraction whereas in forested areas a lateral wave propagation approach is used. The model is applied to an existing GSM-network. The results achieved by this model show good agreement with both wideband and narrowband measurements.<<ETX>>