# Performance Evaluation of Multi-UAV Network Applied to Scanning Rocket Impact Area +
## 5 Description of the Scenarios for FANET Test  
In order to evaluate the network performance in the multi-UAV system, a squadron of quadrotors and a BS were assembled. Some modules were embedded in UAV: an XBee Pro 900 HPS3B module  
Figure 10: Message flow for transmitting an image.  
Figure 9: Flow of CntMs to the BS in a FANET: (**a**) UAV-1 completed the mission without detecting boats; (**b**) the imaging system located a boat, while informing the BS and preparing a DM.  
connected to an XBee Explorer USB module and a power module (Power Bank). The BS is composed of a laptop with communication and test software, while the XBee module is connected to the XBee Explorer USB module.  
During the performed tests, the information is transmitted from the FANET to BS. A laptop performs U2S communication, being responsible for collecting data on the performed simulations. In the multi-UAV system used in CLBI, this node assumes the function of the UAV hub. While the BS corresponds to the GCS in the tests, the UAV hub connects the GCS to the network composed of aircrafts when scanning the rocket impact area.  
The spiral scanning strategy with constant flight speed was adopted without considering area division. The distance for which the nodes have reliable communication was defined through simulation of the maximum range between UAVs. The tests allowed to analyze the time interval required to reorganize the network in case of node loss were analyzed. For this purpose, the latency, transfer rate, received packet rate and signal strength during data transmission was compared in several scenarios.  
The exchange of messages between the BS, which is referred to as ZigBee Coordinator Node (CN) and the HUB UAV constitutes a peer-to-peer network. The XBee modules in the UAVs are configured as ZigBee routers (HUB) and ZigBee End Device (ED), corresponding to a mesh network capable of sending data to the coordinator node which is responsible for forwarding messages from the squadron to the BS and vice-versa, shown in Figure 11. The objective is to evaluate the performance and reliability of the network through data transmission tests, as well as the reconfiguration capability case of the HUB node failure.  
X-CTU(r) free software was used for network management and monitoring [51]. The test and analysis of performance metrics, for example, RSSI, delay time (latency), transmission rate (link speed) packet loss rate and overhead were executed. The transmission of CtIMs and DMs with known and fixed size can then be simulated. Data transmitted in the network can be properly controlled, avoiding packet fragmentation in lower layers.  
The tests were performed with the BS located at the central campus of the Federal University of Rio Grande do Norte, Natal, Brazil, while the UAVs traveled over the sand dune park in Natal, which is a region with a constant wind regime and almost no electromagnetic interference. The tests were executed late in the afternoon during periods with few clouds. Messages were sent with different  
Figure 11: ZigBee devices in a scenario FANET test with mesh configuration.  
transmission rates within the limit supported by XBee. In order to simulate the transmission, a 100-kB image was used to detect boats as described in [PERSON] et al. (2018), where 500 packets of 256 bytes were transmitted. Figure 12 shows the test site.