Propagation model for building blockage in satellite mobile communication systems

Abstract

A propagation model for building blockage in satellite mobile communication systems is developed. This model characterizes the signal transmitted from a low-earth orbiting (LEO) satellite when there is an obstruction in the path of the signal. The obstruction is assumed to be a man-made structure. The analysis is performed using the uniform theory of diffraction (UTD). Using this method, both single and double diffractions from the structure edges were included. Direct and reflected rays from the ground and building were also included, whenever the satellite signal was not completely obstructed. The satellite is assumed to be moving along a circular orbit while the receiver is stationary. The normalized signal level (in decibels) and the signal attenuation rate (in decibels per second) are computed. Such information is considered very useful in developing the mobile system's hand-off algorithm.Index Terms-Geometrical theory of diffraction, satellite mobile communication.

Effects of buildings and trees on satellite mobile communications

“…The attenuation rate also is higher in urban area (0.121 dB/s) as compared with residential area (0.043 dB/s). These values of attenuation rate are small, as compared with LEO system (Tirkas et al 1998) where attenuation rate is 0.359 dB/s in residential and 2.205 dB/s in urban area. This implies lower frequencies of call hand-over from one satellite to another for the MEO system, thus reducing the chance of disconnect.…”

“…The time variation as function of the elevation angle was given in Tirkas et al (1998) for LEO satellite. In the same manner, for MEO satellite in circular orbit with radius R s ¼ 10 355 km that completes an orbit around the earth in 6 hours, the time variation in minutes is given by tðÞ ¼ 57:3 þ sin À1 ð0:45 cos Þ Â Ã À 26:8:…”

“…Different research works focused on the effects of building on satellite mobile communications , Tirkas et al 1998, Leach et al 1999. In (Leach et al 1999), the depolarization effect was considered based on measurements of received signal near the building transmitted from antenna placed on a stationary elevated position.…”

“…Also, wideband effects of building were studied by including only single diffraction and single reflection ). Finally, a propagation model for building blockage in low earth orbit (LEO) satellite mobile communication system was presented (Tirkas et al 1998). This model assumes perfectly conducting walls of the building and focuses on how to predict the signal level at the mobile near the building.…”

Path Loss Models for Air-to-Ground Radio Channels in Urban Environments

“…Their measurements are only valid for mobiles in the middle of a road, since mobiles close to buildings suffer a much higher shadow loss. Tirkas, Wangsvick and Balanis [4] proposed a ray-based theoretical model, but they did not consider the distributions of buildings, streets and terrain in an actual city. This paper develops statistical propagation models for the link between an airborne platform (denoted as Tx) and a mobile terminal (denoted as Rx), with the terminal located within a dense urban environment.…”