ids were used to obtain the DS, ASD, and ZSD at each position. 11.2.4 Outdoor-to-Indoor Scenario 11.2.4.1 Measurement of Path Loss Table 11.7 shows the specifications of the measurement equipment. The transmitter sends a CW, and the received power is recorded at the receiver. The measurement was conducted in the campus of Niigata University, Japan [6, 11, 12]. The measurement environment is illustrated in Figure 11.20. The frequencies used for the measurement were 0.81, 2.2, 4.7, 8.45, 26.4, and 37.1 GHz. Six sleeve antennas for each frequency were installed on a car roof (at B1-B6) or on the roof of a building (at A1-A3) as the BS with simultaneous transmission of the CW signal. The antenna heights were 2.5 or 11.5 m. The measurement was conducted with two receiver units of hand trucks. Each one had three different sleeve antennas installed on it with an interval of 1.5 m between the floor and the antennas. The measurement was repeated on the 1st, 2nd, 4th, 6th, and 8th floors (namely, 1F, 2F, 4F 6F, and 8F). Note that vertically polarized waves were transmitted and received in the measurement. The measured data of received power were post-processed in the following manner: (1) reference points were established every meter. (2) The data at the reference point and other data acquired within 0.5 m before/after the reference point were considered as a data set belonging to the reference point. (3) The median of the data set was determined as the received power at the reference point. (4) Finally, the power was converted to the path loss. In the conventional model [13], the O2I path loss in dB can be basically modeled by PL = PLb +PLtw+PLin. (11.4) Here, PLb is the "basic path loss," which represents the loss in the outdoor scenario, PLtw is the penetration loss into the building, and PLin is the loss inside the building. Table 11.6 Measurement results for indoor hotspot scenarios - office. Tx-Rx #of rays Cluster Cluster Cluster TX positions distances DS (ns) ASD (deg.) ZSD (deg.) # of paths # of clusters per cluste