tal frames and metal doors. The windows are of glass with aluminum frames. Near the windows, there are some concrete pillars. In the measurements, the transmitter of the channel sounder was considered to be the mobile station and was located at points A1-A6, B1-B6, C1, C4, C5, D1, and D4 as shown in Figure 11.19. The height of the sleeve antenna (Tx) was 1.5 m. The receiver of the channel sounder was considered to be the indoor BS and was located at point PO with an antenna height of 2.3 m. At each Tx location, we rotated the horn antenna in both azimuth and elevation and measured five PDPs at each angle combination on the Rx side. At A3, the azimuth angle of the horn antenna was changed from -180° to +180° with a 1° step, and the elevation angle was changed from -80° to +50° with a 1° step. For other Tx locations, the range and resolution of the azimuth angle was not changed, but the elevation angle was changed from -50° to +50° with a 10° step. There were no people moving in the office during the measurements. The antennas were kept within LOS. The data acquisition was performed automatically. Table 11.6 shows the measurement results for indoor hotspot scenarios or offices. Here, the K-Power-Mean method was used to cluster multi-paths. The delay times, 11 Measurements Sleeve antenna Horn antenna 20 GHz 20 GHz Radio wave RF signal RF signal Cesium Received 10 MHz freq. signal Transmission Cesium standard processor 10 MHz signal freq. generator standard PC & storage Transmitter Receiver Sleeve antenna antenna Figure 11.18 The channel sounder configurations. Table 11.5 Channel sounder specifications. Center frequency 19.85 GHz Bandwidth 50 MHz Transmission signal Number of subcarriers Transmission power 30 dBm Tx antenna Sleeve (2.4 dBi) Rx antenna (19.1 dBi: 20 deg. HPBW) 11.2 Propagation Measurements Above 6 GHz Glass window Concrete pillar BS :RX with aluminum frame 2.2 m tall metal locker MS :TX BS (RX) 4.5 m 51.2 m Figure 11.19 Channel sounding in office. azimuth angles, and elevation angles of cluster centro