# NFV/SDN as an Enabler for Dynamic Placement Method of mmWave Embedded UAV Access Base Stations
## 5 Simulation Results  
In this section, we compare the existing methods and the method proposed in Section 4 in terms of per-user throughput. First, we compare three UAV placement methods: the area-edge priority method (existing method in [38]), the K-means method (existing method in [41]), and the method that introduces the smallest-circle problem to the K-means method (proposed in Section 4.1). Next, as a comparison of frequency allocation, we compare three methods: a method without frequency allocation (existing method), a frequency division method for each UAV (proposed in Section 4.2), and a method introducing FFR (proposed in Section 4.3). For the UAV placement method, we use the K-means method with the smallest-circle problem (proposed in Section 4.1). Table 1 shows the parameters used in this paper. As shown in this table, we are considering the use of a millimeter-wave with a center frequency of 28 GHz and a bandwidth of 100 MHz. The 100 MHz bandwidth of the 28 GHz band has been established as a local 5G band that can be used under license in Japan. Here, the additional loss \(\eta\) is derived from the additional loss in other frequency bands described in the literature [44], and the additional loss at 28 GHz is derived by fitting. Environmental variables are variables that represent the environment of the target area. \(\alpha\), \(\beta\), and \(\gamma\) are the ratio of buildings built to the total area of the area, the average number of buildings per unit area [/km\({}^{2}\)], and the scale parameter in the distribution of building height, respectively [38]. These are used to calculate \(a\) and \(b\) in Equation (2) [38]. In this paper, 200 users were placed in a 100 m square area. In this research, we use a user distribution that has a densely populated area to be close to the real environment as described in Section 1. In order to do so, we use the following procedure to generate the desired user distribution. First, we randomly determine the number of hotspots from 0 to 2, and randomly set the position and size of each hotspot. Next, the ratio of the number of users in the hotspot to the overall users is randomly determined. The distribution of users outside the hotspot is then determined to be uniformly distributed over the whole area, with the distribution of users inside the hotspot determined to be uniformly distributed within each hotspot. Finally, the overall user distribution is determined by superimposing the user distributions inside and outside the hotspot [24]. In Figures 7 and 8, five UAVs were deployed for the target user distribution. In Figures 9 and 10, the number of UAVs was varied and the simulation was performed. These four numerical analyses were conducted based on 300 random generations of user distributions. \begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Value** \\ \hline Carrier Frequency & 28 [GHz] \\ Bandwidth & 100 [MHz] \\ EIRP * & 36 [dBm] \\ Beam Width & 45 [degrees] \\ Receive Antenna Gain & 0 [dBi] \\ Temperature & 298 [K] \\ Environmental Constant \((\alpha,\beta,\gamma)\)[38] & 0.3, 500 [km\({}^{-2}\)], 15 [m] \\ Excessive Loss \((\eta_{\text{LoS}},\eta_{\text{NLoS}})\) & 3.5 [dB], 47 [dB] \\ \hline \hline \end{tabular}  
* EIRP: Equivalent Isotropic Radiated Power.  
\end{table} 
Table 1: Numerical parameters. Figure 8: CDF of the data rate for each frequency division method. Figure 7: CDF of the data rate for each UAV deployment method. Based on our simulation setups, numerical analyses were conducted using MATLAB software to compute each user's SINR from which the user data rate can be derived using equations presented in Section 3.2.2. The detailed computation process is presented in Appendix B of this paper. Figure 7 shows the CDF (cumulative distribution function) of the data rate provided to each user for each method of UAV placement, knowing that the decision of which user is associated with which UAV and the total number of users accommodated by each UAV are specified for these different placement methods.