Summary
International Symposium on Antennas and Propagation
2008
Session Number:2A02
Session:
Number:2A02-4
Improvement of 3D Ray Tracing Simulation in Microcell Environment by Introducing the Complex Radar Cross Section
Yukiko Kishiki, Jun-ichi Takada,
pp.-
Publication Date:2008/10/27
Online ISSN:2188-5079
Summary:
For the realization of future generation mobile communication systems, a lot of studies on the propagation channels in various environments are being conducted. Among them, the ray tracing method has been widely studied for the prediction of multipath propagation in various kinds of wireless systems [1]. However, quite some weaknesses are pointed out in ray tracing simulation as follows: i) It is difficult to simulate an object which is smaller than several wavelengths such that geometrical optics (GO) or geometrical theory of diffraction (GTD) cannot be applicable. ii) It is complicated to model curved surfaces or edges although it is not impossible. This paper focuses attention on i) and an outdoor microcell environment is considered. In microcell environment, it is well known that the buildings are major scattering objects. The validity of GO and GTD approximation in ray tracing for the microcell environment however still needs to be examined more carefully. The propagation path loss on an ideal street cell environment using ray tracing simulation exhibits the decrease of path loss and is biased from the experimental results, at long distances. This is a serious problem as this type of environment is typically observed in an urban area. Upon examining the simulation result for this phenomenon, a lot of diffraction edges from objects close to the specular reflection condition were found. This result indicates that the condition of the infinite wedge to calculate the diffraction coefficient is not satisfied. It also implies that the specular reflection and diffraction component cannot be separated and GO approximation cannot be applicable. It is therefore required to check at what distance GO approximation can be applicable. Then the complex radar cross section (RCS) is introduced for ranges where GO is not applicable. Finally, the ray tracing simulator has been expanded to handle RCS. The improvement of the simulation accuracy is validated by measured results.