# Spectrum Values in Suburban/Urban Environments above 1.5 GHz
## 2 Analysis of Spectrum Values
### Urban Environment  
In the urban environment, the user density is very high. Therefore, carriers need to deploy small cells to ensure sufficient user capacity. The cell size becomes much smaller compared to that in the suburban environment. Therefore, the impact of frequency on spectrum values does not reflect the number of cells but rather, the user capacity in a cell. The spectrum values at both lower and higher frequencies have pros and cons in an urban environment. At lower frequencies, the signal experiences less path loss and penetration loss, but the interference from adjacent cells is even higher. Meanwhile, higher frequencies can increase the available bandwidth and decrease the interference but suffer from severe signal loss. Figure 1 presents the cell layout of analysis model. A hexagonal grid site with three sectors is used [8], and the frequency reuse is assumed to be three. In Figure 1, circles indicate the position of the BS and triangles denote the user positions. It was noted in [3] that the achievable capacity of a user in a building with thick walls or near the edge of a cell should be taken into account. Inspired \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameters** & **Hata/SUI Model** \\ \hline TX Antenna Height (m) & 50 \\ RX Antenna Height (m) & 1.5 \\ TX Antenna Gain, \(G_{T}\) (dBi) & 15 \\ RX Antenna Gain, \(G_{R}\) (dBi) & 0 \\ BS TX Power, \(P_{T}\) (dBm) & 46 \\ Thermal noise density (dBm/Hz) & \(-174\) \\ Interference margin (dB) & 5 \\ Cell radius (km) & 5 \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Parameters used in suburban environment [15; 16]. by this suggestion, we divide the users in one cell into eight different groups to represent different conditions including the combination of LoS or NLoS, indoor or outdoor, and cell center or cell edge in Figure 2. According to the propagation conditions, the user types can be mapped to smart city scenarios. The details of the eight user types are summarized in Table 2. The combination of analysis model and user classification method is designed to reflect the complicated and various possible scenarios in urban environment. The achievable maximum capacity for each user type is quantified as a function of carrier frequency by 3D propagation model [8], and thus the effect of frequency on the spectrum value can be investigated. The 3D propagation model includes such diverse parameters as 3D propagation distance, environment height, standard shadow fading, LOS probability, indoor user  
Let us describe in more detail the process of quantifying the maximum capacity of each user type. As the dotted line in Figure 1 shows, when only considering the first-tier interference, the user receives interference signals from three adjacent base stations because of the frequency reuse scheme. The maximum user capacity is calculated from the Shannon capacity Shannon (1954). \[C=B\times\log_{2}(1+SINR) \tag{5}\]  
where \(C\) is the maximum capacity and \(B\) is the bandwidth allocated to each user. Under the assumption that the available bandwidth is 5% of the carrier frequency ([PERSON] _et al._, 2016), it is reasonable to consider different bandwidths for different carrier frequencies since much larger available bandwidth is the main motivation for considering the deployment of high frequency bands. The bandwidth allocated to the user is calculated as ([PERSON] _et al._, 2016):  
\[B=\frac{5\%\times f_{C}}{N_{\textit{reuse}}\times N_{\textit{user}}} \tag{6}\]  
where \(N_{\textit{cell}}=d_{\textit{user}}*Area_{\textit{cell}}\), \(f_{C}\) is the carrier frequency, \(N_{\textit{reuse}}\) is the frequency reuse number, which equals three, \(N_{\textit{user}}\) is the number of users connected to the BS in one cell, and \(d_{\textit{user}}\) is the active user density ([PERSON] _et al._, 2016). \(Area_{\textit{cell}}\) is the area of one cell as follows:  
\[Area_{\textit{cell}}=2.6\times R^{2}=2.6\times\left(\frac{ISD}{3}\right)^{2} \tag{7}\]  
where \(R\) is the cell radius, which equals \(1/3\) of the inter-site Distance (_ISD_).