d 3.9 were different hospitals are presented in [ScFW02]. obtained for the corridor-corridor, room-corridor and The results of the measurements reveal that it is im- room-room classes, respectively. portant to consider the room as a whole, when de- In Figure 4.7-33, the received power is shown (solid termining the attenuation to neighbouring rooms. Slots line) relative to the power measured at 1 m from the BS, and openings in walls give rise to coupling effects through and the results of the combined model for the case of rooms with metallic layers inside the wall. In order to corridor-corridor class (dashed line). Points B and D are accurately investigate wave propagation properties, di- nodes of the recursive model, and at C a loss of 4 dB due verse antennas and measurement systems were used. The to an obstruction is considered. results show a varying behaviour of the wave propagation The millimetre frequency band at 60 GHz is one in different rooms of the hospital. promising candidate to provide transmission data rates The attenuation of single walls was measured by po- up to several hundred megabits per second, and it has sitioning horn antennas on both sides of the wall, and been proposed for future WLANs [Corr01]. From then measuring the attenuation of the transmitted power wideband measurements in rooms and corridors of directly through the wall. Measurements were two different buildings of the Helsinki University of performed at 2.45 and 5.2 GHz, with the antennas po- sitioned at 50 cm from the wall. In Table 4.7-6, the re- sults of the measured attenuation of the walls in hospital I at 2.45 GHz are shown. Table 4.7-7 shows results of wall attenuations mea- NLOS hall: 68+30.1log(d) (oL =1.55) sured in hospital II. Hospital I was newly built in 2000, whereas hospital II was built in 1970. This means that walls are built in different ways, especially those of the rooms for X-ray examinations, which are made of plaster blocks in hospital II. This leads to different results LOS hall: 68+21.7log(d)((o, compare