Shadowing: process models for mobile and personal satellite systems

Several systems for the provision in the near future of mobile and personal communications are presently investigated. Both geostationary or nongeostationary satellites are considered as candidates. In such systems the communication performance depends on the occurrence of shadowing by obstacles on the direct wave component received at the mobile terminal. This paper introduces a "shadowing profile function", which is shown to permit the derivation of the shadowing parameters that appears in existing shadowing process models. Using urban and suburban computer generated areas, the value of the shadowing parameters have been computed from the relevant shadowing profile functions for geostationary and nongeostationary satellites and for vehicular and hand-held terminals over a wide range of elevation angles. The results obtained are in good agreement with measured values for geostationary satellites and vehicular terminals. They also provide further insight into scenarios considering hand-held terminals in connection with nongeostationary satellites.