This work presents a novel three-dimensional (3-D) scattering model to predict the 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. Index Terms-Microcellular measurement, radio channel modeling, ray-tracing technique, scattering cross section. I. INTRODUCTION T HE tremendous growth of cellular mobile radio and the anticipated need for personal communications will create a need for additional communication channels, particularly in densely populated urban areas. The capacity improvement through additional cell splitting in the present generation of cellular radio systems has practical limits because of antenna site constraints. An alternative approach is to use a microcellular structure. Therefore, microcellular systems, such as PHS, DECT, PACS, and CT2 have been introduced in urban or indoor environments [1], [2]. System designers wishing to design a system with optimal frequency assignment and reuse must study in detail microcellular channel characteristics such as median path loss, channel fading, and pulse delay and spread. There are many investigations describing related research [3]-[14]. In this paper, a novel site-specific scattering model is developed for the microcellular channels in urban environment. The analytical scattering model, combined with a patchedwall model, predicts the median path loss more accurately than the conventional analytical ray-tracing model in the cases studied. The patched-wall model has been used to model an indoor radio channel using patches of different dielectric constants and sizes to model indoor walls and boundaries [15]. These patches were assumed to have infinite size in computing Manuscript

The effects of common and basic geometry structures (corridor, comer and floor) in typical office buildings on 1.8 GHz indoor radio propagation were measured. The objective of the study is to provide information about path-loss characteristics for the cell layout of Indoor Personal Communication Services. Based on experimental data, measured propagation losses and developed propagation models are presented.f

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