# Communication Interface Manager for Improving Performance of Heterogeneous UAV Networks
## 6 Obtained Results  
All the experiments were performed using both homogeneous and heterogeneous interfaces, that is, using a single interface (IEEE 802.11n or 802.11p) and using the proposed IM (which switches between them). The performance of each set of experiments is compared and discussed in this section.  
The experiment duration varied for each scenario: circa 18 min for scenario-1 (three nodes), 90 min for scenario-2 (five nodes), and 120 min for scenario-3 (eight nodes). The long simulation time was used to realistically simulate scenarios that execute in the Gazebo simulator. NS-3 converts real time into simulation time, as it uses the metrics of evaluation in its execution logs in the order of ns. As such, the simulated flights of the experiments had a duration of 140 s (three nodes), 150 s (five nodes), and 160 s (eight nodes). To evaluate performance, the experiment duration considered in the NS-3 simulator was used.  
The IM validation occurs at 1 s intervals using the average of the condition decisions from buffers containing at least 10 samples, collected every 100 ms. This avoided instantaneous value fluctuations. The first and last samples were discarded to minimize the effects of the initial and final execution of the networks in the validation of the results.  
Notably, the metrics received from the MAC and PHY layer occur in 1 ns intervals (NS-3 logs), being composed of sensed propagation parameters such as reception and transmission power, path loss, and quantity of transmitted and received bytes.  
The obtained results are presented in two groups: (1) application evaluation, and (2) MAC and PHY evaluation. The application group targeted analyzed the reliability of delivery of messages. Therefore, we observed typical network performance metrics such  
\begin{table}
\begin{tabular}{c c} \hline \hline
**Parameter** & **Setting** \\ \hline Network Topology & Ad Hoc Networks \\ Attenuation Model & Friis Free Space \\ Tx power & 16.02 dBm (40 mW) \\ Maximum Speed & 10, 20, and 30 m/s \\ Fading Model & Nakagami \\ Gazebo Duration Time & 18 min (3), 1 h 30 min (5), 2 h (8) \\ Interface Manager Interval Decision & 1 s \\ Sample Interval & 10 ms,100 ms \\ Packet size & 1472 bytes \\ Interface A & IEEE 80211n 2.4 GHz \\ Range Int. A & 300 m \\ Channel Frequency Int. A & 2.432 GHz (CH 5-6) \\ Interface B & IEEE 80211p 5 GHz \\ Range Int. B & 350 m-1 km (theoretical) \\ Channel Frequency Int. B & 5.860 GHz (CH 172) \\ \hline \hline \end{tabular}
\end{table}
Table 2: Settings adopted in the experiments.  
as throughput, packet delivery rate (PDR), end-to-end delay, and latency. To calculate such metrics, the following variables were monitored during the experiments: bytes and packets transmitted (TX), bytes and packets received (RX), lost packets, packet delivery delay, transmission and reception time, and the successful messages flow. The results from the application group were compiled offline after the simulation was completed. The MAC and PHY evaluation considered standard wireless network metrics: amount of bytes received (Mb), Rx power (dBm), loss (attenuation coefficient in dB), delay (ms), received signal strength indication (RSSI), and noise (dBm). Notably, the results of the MAC and PHY group supported the analysis of the improvement and maintenance in the connectivity between the UAVs during the mission. The results from MAC and PHY results were collected online during the mission execution.