Measurement and modelling of radiowave propagation in urban microcells Citation for published version (APA): Jong, de, Y. L. C. (2001). Measurement and modelling of radiowave propagation in urban microcells. Technische Universiteit Eindhoven. Document status and date: Published: 01/01/2001 Document Version: Publisher’s PDF, also known as Version of Record (includes final page, issue and volume numbers) Please check the document version of this publication: • A submitted manuscript is the version of the article upon submission and before peer-review. There can be important differences between the submitted version and the official published version of record. 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If the publication is distributed under the terms of Article 25fa of the Dutch Copyright Act, indicated by the “Taverne” license above, please follow below link for the End User Agreement: www.tue.nl/taverne Take down policy If you believe that this document breaches copyright please contact us at: [email protected] providing details and we will investigate your claim. Download date: 25. Sep. 2021 Measurement and Modelling of Radiowave Propagation in Urban Microcells Y.L.C. de Jong Measurement and Modelling of Radiowave Propagation in Urban Microcells PROEFSCHRIFT ter verkrijging van de graad van doctor aan de Technische Universiteit Eindhoven, op gezag van de Rector Magnificus, prof.dr. M. Rem, voor een commissie aangewezen door het College voor Promoties in het openbaar te verdedigen op donderdag 21 juni 2001 te 16.00 uur door Yvo L´eon Christiaan de Jong geboren te Vlaardingen Dit proefschrift is goedgekeurd door de promotoren: prof.dr.ir. G. Brussaard en prof.dr. R.J.C. Bultitude Copromotor: dr.ir. M.H.A.J. Herben CIP-DATA LIBRARY TECHNISCHE UNIVERSITEIT EINDHOVEN Jong, Yvo L.C. de Measurement and modelling of radiowave propagation in urban microcells / by Yvo L.C. de Jong. – Eindhoven : Technische Universiteit Eindhoven, 2001. Proefschrift. – ISBN 90-386-1860-3 NUGI 832 Trefw.: mobiele telecommunicatie / radiogolfvoortplanting / elektromagnetische metingen. Subject headings: mobile communication / microcellular radio / radiowave propagation / direction-of-arrival estimation. Cover design by ZO, ’s-Hertogenbosch c 2001 by Y.L.C. de Jong, Dordrecht All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic, mechanical, including photocopy, recording, or any information storage and retrieval system, without the prior written permission of the copyright owner. Aan mijn ouders Aan Nathalie vi Summary The work reported in this thesis is aimed at contributing to a better physical un- derstanding of radiowave propagation in urban microcell environments and, at the same time, to the development of improved propagation prediction models for such environments. Emphasis is placed on the identification, by means of advanced exper- iments, and modelling of the dominant propagation mechanisms in the UHF band. The first part of the study treats the experimental characterisation of urban mo- bile radio channels in terms of the propagation delay and angle-of-arrival of indi- vidual multipath waves, by means of a radio channel sounder in conjunction with a synthetic antenna array. Result of these measurements is the identification of two propagation mechanisms that have hitherto received little or no attention: transmis- sion through buildings and scattering from trees. Building transmission is particu- larly significant in areas directly behind buildings surrounding the base station an- tenna. Scattering from trees can, for example, play a predominant role in propagation around street corners. The second part of the study discusses the development of building transmission and tree-scattering models that can be readily incorporated in ray-based propaga- tion prediction tools. The model for transmission through buildings does not require any information about the buildings other than the exterior coordinates, the complex permittivity of the exterior walls and an effective attenuation coefficient. The lat- ter coefficient characterises the excess loss experienced by radiowaves propagating through a building’s interior and must be determined by measurements. This is done for a large set of buildings. A model for the coherent and incoherent scattering from a single tree is developed with the aid of Twersky’s multiple scattering theory. Nu- merical results from this scattering model show reasonable to good agreement with measured data. The third part of the study presents a new ray-tracing propagation prediction tool that incorporates the transmission and scattering models of the previous part. This tool makes use of a new method to estimate local mean power. Unlike the conven- tional method of adding ray powers, this method also provides accurate values for viii the often occurring case of spatially correlated multipath signals. Path loss predic- tions for two urban microcell environments are shown to illustrate the remarkable improvement in prediction accuracy that can be achieved with the new model. Contents 1 Introduction 1 1.1 Background .............................. 1 1.2 Previous work at TU/e ........................ 3 1.3 Scope and outline of the dissertation . .............. 3 2 High-resolution angle-of-arrival measurements: method 5 2.1 Introduction .............................. 5 2.2 Measurement system ......................... 6 2.2.1 Channel sounder ....................... 7 2.2.2 Synthetic array ........................ 10 2.2.3 Antennas . ......................... 12 2.3 Data model .............................. 14 2.4 Angular superresolution ........................ 16 2.4.1 Beamspace processing .................... 18 2.4.2 UCA-MUSIC ......................... 19 2.4.3 Forward/backward averaging . .............. 20 2.4.4 Effects of a finite data set ................... 21 2.4.5 Summary of the algorithm .................. 23 2.5 Resolution threshold ......................... 23 2.6 Numerical results . ......................... 26 2.6.1 Resolution threshold ..................... 26 2.6.2 Estimation of the number of signals ............. 28 2.7 Experimental results ......................... 30 2.8 Conclusions .............................. 32 3 High-resolution angle-of-arrival measurements: results 35 3.1 Introduction .............................. 35 3.2 Transmission through buildings .................... 36 3.2.1 Realistic urban microcell environment – Bern ........ 36 x Contents 3.2.2 Controlled environment ................... 40 3.3 Scattering from trees . ........................ 42 3.3.1 Realistic urban microcell environment – Fribourg ...... 42 3.3.2 Controlled environment ................... 46 3.4 Conclusions .............................. 48 4 Propagation into and through buildings 49 4.1 Introduction .............................. 49 4.2 Building transmission model ..................... 51 4.2.1 Surface fields . ........................ 52 4.2.2 Interior fields . ........................ 54 4.2.3 Transmitted fields ....................... 58 4.2.4 External scattering ...................... 60 4.3 Numerical results . ........................ 61 4.3.1 Field around a building corner . ............. 61 4.3.2 Field behind a building .................... 63 4.4 Experimental results . ........................ 65 4.4.1 Measurement equipment and procedure ........... 66 4.4.2 Determination of the transmitted field ............ 66 4.4.3 Determination of the attenuation coefficient ......... 68 4.4.4 Reproducibility ........................ 69 4.4.5 Description of the buildings ................. 71 4.4.6 Results ............................ 71 4.5 Conclusions .............................. 77 5 Scattering from trees 79 5.1 Introduction .............................. 79 5.2 Vegetation model . ........................ 80 5.2.1 Overall problem geometry .................. 81 5.2.2 Scattering from branches ................... 82 5.2.3 Scattering from leaves .................... 84 5.2.4 Equivalent scattering amplitude and cross section ...... 86 5.3 Scattered field ............................. 88 5.3.1 Mean field inside the canopy ................. 88 5.3.2 Coherent scattered field .................... 90 5.3.3 Incoherent scattered field ................... 94 5.4 Numerical results . ........................ 96 5.4.1 Branch and leaf parameters .................. 96 5.4.2 Attenuation coefficients ................... 98 Contents xi 5.4.3 Scattering cross sections of branches and leaves ....... 98 5.4.4 Coherent scattered field ...................