# Channel Measurement and Modeling for 5G Urban Microcellular Scenarios
## 4 Evaluations
### Path Loss  
In this section, the local area PL is analyzed. To mitigate the strong fading of the first MPC as observed in Figure 3 and to eliminate a bandwidth dependence of the PL, a spatial averaging over at least one fading period must be performed [16]. In the present case, this could be achieved by choosing \(K=3125\), which corresponds to 1.25 m RX movement. The local area channel gain \(G_{\mathrm{C}}\) was calculated by integrating over the entire APDP and subtracting the estimated noise power \(P_{N}\). For omnidirectional antennas, the antenna-deconvolved local area PL is then given by  
\[L_{\mathrm{PL|dB}}=-10\log_{10}G_{\mathrm{C}}+G_{\mathrm{TX|dB}}+G_{\mathrm{ RX|dB}}\,, \tag{2}\]  
where \(G_{\mathrm{TX}}\) and \(G_{\mathrm{RX}}\) are the antenna gains at the TX and the RX. Figure 3(a) illustrates the PL for the measurement runs with LOS (no blockage). As explained above, each data point results from 3125 CIRs. Data from distances below 5 m has been discarded, since the received power was significantly reduced by the elevation beamwidth of the antennas (at \(d=2\) m, the RX antenna was directly below the  
Figure 3: Evolution of averaged power delay profiles (APDPs) over time for TX position Tx1 and mobile RX on Track Rx1 from (**a**) measurement and (**b**) simulation. TX antenna). In addition to the calculated PL, the log-distance least-squares (LS) fit is shown. It relates to the well-known PL exponent model with a floating intercept point (IP) [31]:  
\[L_{\text{PL}}(d)_{\text{|dB}}=\overline{L}_{\text{PL}}(d_{0})_{\text{|dB}}+10n \log_{10}\left(\frac{d}{d_{0}}\right)+X_{\sigma}, \tag{3}\]  
where \(d\) denotes the TX-RX distance. The IP \(\overline{L}_{\text{PL}}(d_{0})_{\text{|dB}}\) is the mean PL at the reference distance \(d_{0}\), \(n\) is the PL exponent and \(X_{\sigma}\) is a zero-mean Gaussian random variable (in dB) with standard deviation \(\sigma\), which accounts for shadow fading. The linear regression yields \(\overline{L}_{\text{PL}}(d_{0})=82.3\,\text{dB}\) for \(d_{0}=5\,\text{m}\), \(n=1.88\) and \(\sigma=1.03\,\text{dB}\). Hence, the IP is very close to free space propagation (\(82.0\,\text{dB}\)) and \(n\) is slightly below. The same evaluation is shown for the SC-CC scenario in Figure 4b. In this case, the IP is \(\overline{L}_{\text{PL}}(d_{0})=81.9\,\text{dB}\) for \(d_{0}=5\,\text{m}\), and a PL exponent of \(n=2.13\) is obtained. The shadow fading standard deviation is slightly higher, namely \(\sigma=2.03\,\text{dB}\). Table 2 summarizes the PL parameters for all measured UMi scenarios. The IP is given for the reference distance of \(d_{0}=1\,\text{m}\) to be comparable with most of the literature values. Nevertheless, the models should not be applied outside the distance range, which has been used for the LS fit, namely the range where reliable measurement data is available without outage. It is denoted as validity range in Table 2. If for comparison reasons a different reference distance \(\tilde{d}_{0}\) shall be used, the new IP can simply be derived from the model itself by calculating \(\overline{L}_{\text{PL}}(\tilde{d}_{0})_{\text{|dB}}=\overline{L}_{\text{PL}} (d_{0})_{\text{|dB}}+10n\log_{10}\left(\frac{d_{0}}{d_{0}}\right)\). \(n\) and \(\sigma\) are not affected as a matter of principle. Under LOS conditions, \(n\) is basically close free-space propagation. A significantly smaller value (\(n=1.62\)) only occurs in the street canyon at \(10\,\text{GHz}\). It can be caused by a waveguiding effect, which is not significant at \(60\,\text{ GHz}\). With \(57.7\,\text{ dB}\), the IP at \(d_{0}=1\,\text{m}\) is significantly higher than the theoretical PL in free space (\(52.4\,\text{dB}\)), which is an effect of the LS fit in connection with \(n<2\). (Note that \(d=1\,\text{m}\) is beyond the validity range.) As expected, the IP is larger for non-line-of-sight (NLOS), since the transition from LOS to NLOS results in a significant drop of the received power [16; 32]. It is noteworthy that the NLOS scenario yields surprisingly low PL exponents.