Effects of buildings and trees on satellite mobile communications

Abstract

A propagation model for lossy building with tree attenuation in urban and residential areas is developed for satellite mobile communications. This model is used to characterize the signal transmitted from medium earth orbit (MEO) satellite when there are buildings and trees in the path of the signal. The analysis is performed using the uniform theory of diffraction (UTD). The tree attenuation is evaluated through the modified exponential decay model (MED).The normalized signal level and signal attenuation rate are computed. Such information is useful in developing the mobile system's hand-off algorithm. In narrowband systems, the propagation attenuation and fading statistics are the main causes of signal degradation. So, the probability of error is calculated with and without the existence of the tree. Also the axial ratio (AR) is computed as function of satellite elevation angle. In wide band systems, the delay-spread is dominant because of the inter-symbol interference. For such case, the coherence bandwidth and impulse response are computed. Along with that, computed results are compared with actual measured data.

Predicting leaf state effects on radiowaves based on propagation loss measurements

“…The distribution function of the fading channel was found to be Rician [8], [9], [10] for cellular communications. The uniform theory of diffraction was applied to calculate the path loss in the presence of lossy trees and buildings for satellite mobile communications [11]. An empirical model was used to represent the propagation loss associated with near ground communications in a tropical forest [12].…”