ition and distance between measurements performed in Munich at handling cost reduction. The term hybrid refers to the fact 947 MHz (COST 231 blind test) and model prediction is that, while simplifying, statistical elements are necessarily shown in Figure 4.7-24(a): the agreement is quite good introduced in the deterministic approach. Unfortunately, and we can observe that the vertical and lateral contribu- the simplification of an intrinsically complex propagation tions, as expected, equal each other at a distance of about process can indeed yield simple models, but at the ex- 650 m. Figure 4.7-24(b) reports the received field stan- pense of a proliferation of arbitrary parameters, which dard deviation as a function of the distance. From the often need to be determined using measurements or RT figures we may conclude that the developed model is able simulations. It is interesting to notice that some simplified to reproduce the experimental values of mean path loss models for indoor environments [LoCo05], [WWWW04] and standard deviation with good accuracy once the values often yield better accuracy in field strength predictions of the involved parameters are tuned to the actual envi- than sophisticated 3D RT tools. This is probably due to the ronment. It is worth highlighting that the model does not inherent calibration with measurements present in sim- require a detailed building database. plified models which permits them to take into account In [WWWW04] a new semi-deterministic model for the effect of environment cluttering (furniture, etc.) as field prediction in both the indoor and outdoor environ- opposed to conventional ray models which rely only on ment is proposed. The model is aimed at taking into ac- architect CAD plans. In principle, a good simplified model count only the dominant paths in each scenario and CHAPTER 4.7 Propagation modelling and channel characterisation measurements measurements regression line model-latera attenuation model model-vertical attenuation model-total attenuation Distance fr