Development of a Radio Propagation Model Based on Slope Diffraction and Convex Hull Techniques
Dr. Ali Kara (Project Coordinator)
Mehmet Baris Tabakcioglu
Development of powerful radio planning tools has a great importance for cellular communication systems. They are required in estimation of planning parameters, such as base station location, cell geometry, frequency assignment, co-channel/adjacent channel interferences etc., especially in urban areas where user density is relatively high. With radio planning tools, cellular system operators are able to install a system in a particular geographic region without performing expensive and time-consuming field measurements. Propagation models in the background of radio planning tools use mostly ray-tracing techniques based on the Geometrical Theory of Diffraction (GTD). GTD, however, predicts inaccurate fields in multiple transition zones occuring in built up areas where buildings are of the same or similar heigths. An extension to the GTD, the Slope Diffraction, has been proposed to increase the accuracy but computation time is also increased.
In this project, a 2D propagation model combining the slope diffraction and convex hull techniques will be developed for urban radio propagation. The model will be based on the use Fresnel regions concept along with convex hull technique in order to reduce the computation time in the application of slope diffraction in multiple transition zones. For a multi-building structure, effective building number will be determined by eliminating the buildings whose Fresnel numbers are less than a “critical number”. This critical number will be estimated by performing extensive simulations. As previous studies in the literature, buildings could be simulated by either absorbing knife adges or impedance wedges with different inner angles.