Modification of the UTD Model for Cellular Mobile Communication in an Urban Environment

Abstract

In this paper we modified the reflection coefficient of electromagnetic wave incident on the wall of buildings or obstacles that occurs in the mobile communication path by solving the nonlinear Riccati equations. For this purpose, the building walls are assumed to be inhomogeneous layers of brick and concrete where permittivity changes as a function of the wall thickness. Based on reflection coefficient modification, we proposed a new propagation model using uniform geometrical theory of diffraction (UTD) and geometrical theory of diffraction (GTD) for multiple diffraction paths in cellular mobile radio communication, and calculate the diffraction loss as well as the path loss for a row of buildings with two inhomogeneous faces. The measured reflection coefficient and diffraction loss are then compared to the theoretical results obtained from the proposed model. Our observations reveal good agreement between measurement data and theoretical results. Therefore it can be concluded that the modified reflection coefficient can adequately predict the reflective properties of the wall surfaces with different dielectric properties. So the modified reflection coefficient as well as the new UTD model can directly be applied for field estimation or diffraction loss calculation, as well as multipath signal strength or delay prediction in ray tracing algorithms used in mobile communication, radar, and radio links.