A Study on Vegetation Loss Model with Seasonal Characteristics

In cellular mobile communications, it is necessary to accurately estimate and evaluate the influence of the environment between the base station and the mobile station, such as the terrain, clutter of buildings, vegetation, and the influence of human bodies. Rural areas have few buildings, i.e. few surrounding reflective objects, and so are not multipath-rich environments. Therefore, it is considered that the received power is greatly reduced when direct waves are blocked by buildings, trees, human bodies, etc. In such an environment, it is necessary to clarify the characteristics of diffracted waves / waves scattered by isolated buildings, vegetation, and the human body. Further, this concept can also be applied to HAPS (High-Altitude Platform Station) environments on which research is currently very active. This paper focuses on the loss due to vegetation blockage. The loss due to vegetation has been standardized as ITU-R Recommendation P.833-9, but the region and kinds of trees considered are limited. In this paper, we measure and analyze the vegetation loss of deciduous trees in different seasons in Japan. From the results, we propose a new vegetation loss model that can take transmission frequency and seasonal characteristics into consideration.