ferent computer runs. (a) Wall imperfection model (b) Spatial sampling approach Number of computer runs Average field value [dB] Number of runs (separation: X/4) Average field value [dB] -18.92 100 (2.5) X 2.51) -20.52 -19.39 400 (51 X 51) -19.32 -19.34 1600 (10) X 101) -19.30 -19.22 6400 (20% X 201) -19.34 -19.45 Propagation modelling and channel characterisation CHAPTER 4.7 535 m MS in street canyon MS in cross-way MS general 719 m Figure 4.7-21 Top view of the simulation environment. (mobile station - MT) has an antenna height of 1.7 m Hata-like model (a) and by the RT model (b). It is evi- above ground. A N/2 dipole is used as both transmitting dent that the empirical model, although taking into ac- and receiving antenna. The channel impulse responses count the pattern of the antennas, is not able to are collected in nine different simulation routes, sepa- reproduce the interaction of the propagating field with rated in three different propagation classes: [RX1]- the urban layout, which is on the contrary evident on (b). [RX4] capture street canyons, [RX5]-[RX7] in- Of course, such a huge difference reflects on system tersection and [RX8]-[RX9] capture all propagation performance assessments as well. It is shown in the paper classes. Considerations regarding the behaviour of the that a UMTS system simulation with the empirical multipath pattern in different route classes show a good propagation engine leads to less than 1% rejection rate agreement with that-reported in [LKTH02]. Table 4.7-4 Rjr, with summarises the statistical parameters for all simulation routes. Comparing scenario I (street canyon) with sce- RjR = (number of rejected calls/total number of calls) nario II (intersection), one can see that at intersections time and angle spreads are higher than in the latter. while the same simulation with RT leads to Rjr = 20%. Probably, at intersections waves are not influenced by A group of researchers from the University of street guiding effect and thus energy is spread over Stuttgart and from AWE Communi