# Communication Interface Manager for Improving Performance of Heterogeneous UAV Networks
## 6 Obtained Results
### Final Remarks  
Recalling the application metrics, we observed that the IM produced more than twice the average throughput of the best-performing interface applied in homogeneously. This performance allows sending a reasonable amount of GPS coordinates per second and enough frames per second of low-resolution video streaming (640 \(\times\) 420, 480p). This condition is suitable for low-complexity SAR missions of up to 1 km of total area. We noticed, however, that in the eight-node scenario, the adoption of signal relay would be ideal for increased video transmission resolution.  
Another relevant aspect relates to the amount of packets trafficked in the network, where the IM also achieved the highest proportion of transmitted and received packets, which resulted in a more efficient network, allowing a larger flow of effective messages. PDR was used to evaluate the packet delivery network capacity, where the IM managed to achieve 0.977% in the five-node scenarios, around 15 times better than using homogeneously applied interfaces. In terms of average end-to-end delay, the IM performed the worst because this metric also includes the time spent before source transmission, and the IM requires time for the spectrum evaluation and computing its decisions. In any case, the IM still presented the best performance considering the higher amount of successfully delivered messages.  
In terms of MAC and PHY metrics, we observed that the IM maintained the exchange of messages during longer time intervals compared with interfaces applied separately. This represents more time available for communication between nodes and a larger amount  
Figure 14: Delay (ms) aggregated by number of samples (amount of 10 ms).  
of received data. For the experiments with more than 100 m between vehicles on sparse routes, the IM predominately selected 802.11p for use in most of the nodes. This means that the IM properly selected the safest interface to maintain network connectivity, since 802.11p provided the best signal reception (Rx power and RSSI), maintaining the intensity of noise and signal losses within acceptable levels with an imperceptible delay rate for the type of traffic adopted.  
The obtained results also allowed to reinforce the assumption that all adopted criteria for selecting the best interface should be used with similar weights. For example, if increasing the weight of the amount of received bytes, for instance, these bytes could be constituted by trash or truncated messages in the presence of high loss and low RSSI.  
Finally, even with the lower flow rates presented by the IM (Figures 10 and 13), using the IM allowed increased stability in the transmissions, with continuous growth and less fluctuations, reducing the traffic interruptions caused by signal losses. This reinforces the assumption that the adopted metrics for selecting the best interface should be used with similar weights. If, for instance, a higher weight were given to the amount of bytes received, the 801.11n interface would have been selected, but there would not be as much successfully delivered messages at the destination nodes as achieved in the conducted experiments.