Near and far field models for scattering analysis of buildings in wireless communications

Abstract : This paper presents an efficient building modeling for urban propagation prediction. By dividing the whole computation area into near and far zones, two different models are adopted for buildings. As demonstrated for a building facade, a precise description of the heterogeneities is necessary for an observation point situated in the building near-field, whereas in the far-field area a good accuracy is maintained by homogenizing the facade electric properties. Therefore, in the far area, a homogenized reflection coefficient is taken for each facade, and an RCS (Radar Cross Section) is calculated for one or a set of far buildings, taking the multiple reflections into account. In a near area, the simulator can apply the classical ray tracing code using the detailed facade description while taking account of far building groups through their RCS. The distance of homogenization and RCS validity is obtained using a reference method based on Green's functions.