eld distance, with a tude of the scattered field and the amplitude of the quantisation of AA = = 1 degree. A total of M = 105 incident field in the vicinity of the surface. In case of a far realisations is taken for the ensemble averaging. wall, the square of the total scattered field amplitude is: Figure 4.7-15 depicts the components of the Radar Cross Section (RCS) matrix per unit area of the diffuse (or incoherent) scattering component for the Kirchhoff model 60GtPt, with stationary phase approximation, Figure 4.7-15(a), and for the stochastic scattering approach, Figure 4.7-15(b). (4.7.2) Propagation modelling and channel characterisation CHAPTER 4.7 (a) Computed with the Kirchhoff method. (b) Computed with the ray-optical stochastic approach. Figure 4.7-15 RCS matrix elements per unit area (ooo, opp) of a square rough surface. Direction of illumination: (Ai=60°, =0°). where Gt and Pt are the gain and the input power of the TX antenna, respectively, and A is the area of the wall. Angles and distances in (4.7.2) correspond to that depicted in Figure 4.7-16. In order for the overall power balance to be satisfied, specular reflection and diffraction are consequently attenuated according to the Rayleigh factor R. Realistic S and R values for typical buildings have been found to be S = 0.4 and R = 0.6 [DeBe99]. For simplicity, only first-order scattering is considered. Re- sults reported in [DEGDA04] show comparisons of measured and simulated power delay profiles relative to Figure 4.7-16 View of the generic surface element with incidence (Ai) and scattering (As) angles. CHAPTER 4.7 Propagation modelling and channel characterisation a macrocellular scenario in the city of Stockholm. The reported in [DeFG03], where simulations of the RtS diffuse component is shown to be of major importance, mechanism in typical cases are carried out using RT in- especially for wideband assessments in macrocells. In cluding ER scattering in the vertical plane, diffuse scat- Figure 4.7-17, for example, the agreement is quite good ter