# Aerial Coverage Analysis of Cellular Systems at LTE and mmWave Frequencies Using 3D City Models
## 3 Simulation Results
### LTE vs. mmWave  
Given our 3D propagation model, it is possible to realistically compare coverage performance of LTE with 5G or mmWave. For this simulation, full-load and the three sector case is considered, and it is assumed that the LTE and mmWave BSs all have the same location. First, the SINR curves are generated, followed by the coverage probability curves. The results of the simulation, as shown in Figure 6, indicate that SINR is significantly decreased (with respect to the ground level) for high UAV altitudes, because of interference. For ground users, LTE at 1.8 GHz outperforms the mmWave band by approximately 4 dB on mean SINR if the same bandwidth of 20 MHz is considered. This difference is due to the fact that,  
Figure 5: Statistics extracted from the 3D map. Figure 6: Mean SINR as a function of height AGL. for mmWave, users having a NLOS link receive almost zero power (\(P_{rx}\approx 0\)) from their serving base station, thus the received power is below the noise floor, resulting in a negative SINR, even when the interfering signals are blocked. For an increased bandwidth of 400 MHz, the SINR levels at the ground level are even lower due to the increase in noise power, while the serving and interfering signal's power stay the same. Right above rooftop height (13.32 m), we can observe a peak in SINR for both LTE and mmWave. Both peaks can be explained by the fact that a user will be likely to get a LOS connection with its serving base station, while all interfering BSs, which are at a larger distance of the user, will still be in NLOS. The existence of both peaks is in line with multiple research contributions dedicated to optimal positioning of an AUE [8; 29]. The maximum mean SINR of the mmWave system occurs at a slightly higher altitude. For high altitudes, SINR decreases for both LTE and mmWave as more interfering base stations will have a LOS link. Interestingly, increasing the bandwidth does not affect mean SINR at high altitudes, meaning that at high altitude interference becomes the major limiting factor for both considered carrier frequencies, regardless of the bandwidth used. For high altitudes (>50 m), the difference in SINR of both frequencies is constant. This difference can be attributed to the frequency difference which results in a fixed difference in PL, which behaves as a free space path loss at these altitudes. Figure 7 shows the cumulative distribution function of SINR in function of altitude. For one specific altitude, all SINR values are considered and plotted as a distribution, for both LTE and mmWave scenarios. We can see that, for altitudes up to right above rooftop, the SINR spread is limited to a range of \(-5\) dB to +20 dB for \(B=20\) MHz. Increasing the bandwidth results in a larger spread for the altitudes below the rooftop; however, when interference becomes high due to higher LOS probability, SINR distributions for both bandwidths behave identically. Moreover, at the altitude of 35 m, the distribution for LTE and mmWave is more or less the same. For high altitudes, the SINR is almost constant and there exists a fixed difference between LTE and mmWave SINR, as explained in previous paragraph. When looking at the results of coverage probability, LTE has better terrestrial coverage due to the lower PL in this frequency band (see Figure 8). For the full-load case, we notice that, for ground users in the mmWave scenarios, the coverage probability is not 100% while for LTE it is, as expected from our simulations. The low coverage probability can be explained by the lower SINR values for ground users using mmWave as the results in Figure 7 show, especially for the 400 MHz bandwidth scenario almost 40 % of the spread is located below \(-6\) dB, while for LTE the complete spread is located above \(-6\) dB. After reaching its peak at a height of 22 m AGL, which is above the average rooftop height, mmWave coverage probability drops faster than LTE's and reaches zero at an altitude approximately 50 m lower than LTE.