.7.1) tant in public mobile radio systems (GSM, UMTS) and Digital Video Broadcasting systems, where most users where Loutside is the path loss calculated outside before are often located in indoors. In [LoCo02b], [CoLA03] penetration, Linterface is the average loss due to the and [LoCo05] also a quasi-3D RT tool is used for transmission through the facade, dindoor is the path length indoor prediction in case of outdoor and/or indoor BSs inside the building and Llinear the average loss due to the (WLAN networks). The quasi-3D RT tool, which is in-building propagation taking into account furniture and perfectly integrated with the 2.5D outdoor one, adopts partition attenuation. An example of outdoor-to-indoor a 2D approach in the horizontal plane (a plane parallel coverage prediction derived using formula 4.7.1 is to each floor) plus reflections on the floor and the ceiling. reported in Figure 4.7-11. It is evident that coverage in Of course the indoor RT model allows the detailed Tx (Sofitelly -30 dBm -40 dBm -50 dBm -60 dBm -70 dBm Figure 4.7-11 Examples of outdoor-to-indoor coverage. Propagation modelling and channel characterisation CHAPTER 4.7 computation of indoor multipath effects. In [LoCo05], RX1 (solid) however, it is shown that the empirical-statistical method RX2 (dashed) (formula 4.7.1) outperforms 3D RT as regards outdoor- RX3 (dotted) RX4 (dash-dot) to-indoor coverage prediction. This is probably due to the great degree of environment cluttering indoors (furni- ture, etc.) not taken into account by the RT model, which only relies on architect Computer Aided Design (CAD) plans. Also [JePK05] considers 3D RT for indoor propaga- tion prediction. In this work, a full 3D RT tool, which considers multiple reflections, edge diffractions using UTD coefficients (see Subsection 4.7.2) and trans- missions through walls, is used in combination with measurement data to determine the electromagnetic parameters of walls (see Subsection 4.7.3.2). This is Measurements (ns) a very important application of ray models, 