1.9-GHz-band radio propagation characteristics in an open urban environment and tree loss prediction using a loss layer model

For design of optimum microcells on a university campus, it is necessary to determine the propagation characteristics within a propagation environment represented by a relatively large open space scattered with large building s and many trees. In this paper, for the radiated waves from seven PHS base sites at 1.9 GHz experimentally installed on the campus of Hokkaido Univer sity from 1993 to 1994, a median received signal level measurement method i s proposed that can be applied in unpaved garden areas (with glass and pebb les) as well as in areas with woods, vegetation, and hilly terrain, and its effectiveness is discussed. Next, for quantitative evaluations of the incr ease of the propagation loss due to trees in the propagation paths on the c ampus, a propagation model is proposed that consists of the loss layer mode l and the geometrical optics two-ray model. In the loss layer model, the lo ss due to trees is replaced with a loss per unit length of the propagation path. The estimated median received signal level and the measured value are compared to determine the effectiveness of the model. The increase of the propagation loss on the campus due to trees can be estimated if the loss pe r unit length of the tree layer by the present loss layer model is chosen t o be about 0.1 dB/m for the base site antenna installed on the rooftop of t he building and 0.07 to 0.09 dB/m for the antenna installed on the roof of the public phone box. (C) 2001 Scripta Technica