New Modified Urban Canyon Models for Satellite Signal Propagation Prediction

The effects of high-rise buildings on satellite propagation in the vicinity of urban canyons are investigated. A comparison between a conventional canyon model and the two modified canyon models, which take into account the presence of high-rise buildings, is presented for both narrow-band and wideband signal cases. The narrow band is developed using ray tracing (RT) and includes the direct wave, the specular reflection from building walls and ground, and the diffracted waves. In addition, multiple shadow boundaries are defined and used to carry out the uniform theory of diffraction calculations. The incident shadow boundary is the dominant boundary and is used to determine the line-of-sight region for all cases, while wall and ground reflection shadow boundaries are used to obtain higher precision due to multiple reflections. The wideband model is developed by applying a channel transfer function to the data obtained from the RT method. The proposed models are used to predict the received signal in a realistic urban environment from satellites. The models are applicable to any satellite link application, such as global navigation satellite systems, low Earth-orbiting, and high-altitude platform systems, and the results are obtained for a satellite transmitting two linearly polarized signals at a frequency of 1.625 GHz. It is found that the presence of high-rise buildings next to a street canyon can significantly alter the visibility of satellites, which, in turn, lead to an increase in path loss. Consequently, ignoring high-rise buildings in the proximity of a street canyon can lead to a path loss difference of as much as 30 dB.