## 3 Parameter Extraction and Measurement Results
### Measurement Results  
Table 2 shows the measured channel characterization results for the two frequency bands with the directional antennas in the corridor scenario. The following findings can be summarized: (1) the differences in the path loss exponent, shadow fading standard deviation, RMS delay spread and coherence bandwidth for the two frequency bands are minimal; (2) the path loss at 14.6 GHz is larger than that at 3.6 GHz. As expected, the difference is about \(20 log_{10}(14.6\) GHz\(/3.6\) GHz\()=12.16\) dB between the two carrier frequencies; and (3) there is no significant difference in all of the extracted propagation characteristics between different antenna locations (near the wall or in the middle of the corridor).  
The path loss exponent in the corridor ranges from 1.51 to 1.69 (see Table 2), smaller than two (which corresponds to the free-space propagation). This implies a waveguide phenomenon due to the confined structure of the corridor. In addition, the minimal difference between different antenna locations (near the wall or in the middle) implies that the wave-guide effect is not very sensitive to the antenna-wall distance in the corridor scenario with the directional antennas. The standard deviation of shadow fading ranges from 1.79 to 2.27 dB, which agrees with those measurements in corridors at 2.4 GHz, 5.3 GHz, and 60 GHz [20; 21; 22].  
No single definitive value of correlation has emerged for the specification of coherence bandwidth. Hence, coherence bandwidths for generally accepted values of correlations coefficient equal to 0.5, 0.7 and 0.9 are evaluated, and these are referred to as \(B_{0.5}\), \(B_{0.7}\) and \(B_{0.9}\). Furthermore, the coherence bandwidth is highly variable with the locations of receiver. By convention, cumulative distribution function (CDF) of the coherence bandwidth is computed and the level below which the coherence bandwidth stays for a given percentage is used to interpret the coherence bandwidth results [13]. As shown in Table 2, the level of \(B_{0.5}\), \(B_{0.7}\) and \(B_{0.9}\) for 90% of receiver positions is about 320 MHz, 120 MHz and 40 MHz, respectively. The communication system designers sometimes rely on the lowest value of the coherence bandwidth. Thus, the lowest value, \(B_{\rho,min}\), is also listed in Table 2.  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Measured Parameters**} & \multicolumn{2}{c}{**3.6 GHz Band**} & \multicolumn{2}{c}{**14.6 GHz Band**} \\ \cline{2-5}  & **In the Middle** & **Near the Wall** & **In the Middle** & **Near the Wall** \\ \hline Path Loss Exponent & 1.51 & 1.69 & 1.67 & 1.58 \\ Fit Intercept (dB) & 47.8 & 46.8 & 57.8 & 58.9 \\ Shadow Fading Standard (dB) & 1.79 & 2.19 & 2.27 & 2.16 \\ Mean of RMS Delay Spread (ns) & 12.94 & 13.04 & 14.84 & 13.87 \\ \(B_{0.5}\) (MHz) & 324.95 & 316.19 & 322.27 & 324.56 \\ \(B_{0.7}\) (MHz) & 115.92 & 126.29 & 117.42 & 122.60 \\ \(B_{0.9}\) (MHz) & 37.21 & 42.91 & 43.15 & 42.17 \\ \(B_{0.5,min}\) (MHz) & 11.01 & 11.22 & 12.05 & 11.70 \\ \(B_{0.7,min}\) (MHz) & 5.21 & 6.07 & 5.16 & 5.78 \\ \(B_{0.9,min}\) (MHz) & 1.52 & 1.62 & 1.77 & 1.40 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Measurement results at the two frequency bands.