*4.4. Transmission Range*

We varied maximum transmission power of 50 UAVs, in various *n* values. Figure 13 shows the numerical results compared to FC and SMST cases. In Figure 13a, we cut the transmission power over 0.5 mW for visuality. The results in this figure have several considerations. At first, while FC cases have exponentially increasing power consumption when the maximum transmission power increases, the cases of SMST and TC-*n* have mostly constant power consumptions. This result indicates that SMST and TC-*n* can sustain similar efficiency in various cases of the maximum transmission power. Then, the outperformance of the TC-*n* against the SMST originates from the packet-level power control and the partitioning-based link pruning, as mentioned in the former subsections. Secondly, there is a saturation while increasing the maximum transmission power, after about 22 dBm, both in the hop counts and the degrees. The reason for this phenomenon is that the nearest neighbors of certain directions are selected despite the transmission range expansion. For this reason, the saturation starts earlier when *n* is smaller, as shown in Figure 13b,c. The saturation indicates that our topology control layer outperforms results even at the smaller transmission range.

We summarize our simulation results as follows.


**Figure 13.** Numerical results while varying maximum transmission power. (**a**) Average power consumption; (**b**) Average hop count; (**c**) Average node degree.

From the aforementioned statements, we claim that the topology control layer can contribute to the energy-efficient communication in the UAV network, in wide range of the environments.
