# Performance Evaluation of Multi-UAV Network Applied to Scanning Rocket Impact Area +
## 1 Introduction
The data transmission system must be capable of sending telemetry messages associated with the swept area, while also informing if any ship is found and, if so, sending an image of the target to the BS. Since the rocket impact area is offshore, that is, in the Atlantic Ocean, the communication infrastructure can be provided by the aircraft themselves by establishing a FANET among the UAVs. This work aims to develop and validate the performance of a FANET architecture. It intends to ensure the transmission of control data and images from ships located in a restricted offshore area using a network composed of ZigBee sensors embedded in a UAV squadron. The aircraft are responsible for scanning the impact area of rocketslaunched offshore by the CLBI so that the eventual presence of intruders is detected efficiently and reliably in a less time-consuming and low-cost approach. Some works, for example, [PERSON] et al. [22] present the design, communication protocol and testing procedure of a system for sending UAV telemetry messages to a ground control station (GCS) using ZigBee protocol. [PERSON] et al. [23], [PERSON] [24] proposes a cooperative aerial-ground vehicular network architecture, which employs ZigBee to send telemetry messages and a Wi-Fi network to send images aiming at disaster rescue missions or area investigation. [PERSON] et al. [7] designed a UAV communication protocol for Wi-Fi networks based on time division multiple access (TDMA) transmission at the network layer. Besides, due to delayed packet delivery issues, the use of a model that supports a guaranteed time slot (GTS) is suggested based on the ZigBee protocol associated with the network link layer. [PERSON] et al. [25] proposed a testing platform relying on IEEE 802.15.4-based communication between UAVs for exchanging data with ground sensors to monitor and control automated crops. [PERSON] et al. [26] considered the use of unmanned robotic vehicles in maritime operations, where the main communication restrictions between the vehicles and mission controller are associated with long distances and/or low-power transmissions. In this context, it is reasonable to state that the aforementioned works have used Wi-Fi to transmit images, as well as ZigBee or Wi-Fi protocol to send telemetry data between the UAVs and the base station. The particular difference of the proposed study lies in the development and test of a communication protocol to be embedded in a Multi-UAV system to transmit images and information in a real-time approach from UAV to UAV (U2U) based on XBee sensors that employ ZigBee protocol. The tests are performed on quadrotors model DJI Phantom 3. The multi-UAV communication system is embedded in the aircraft by their respective manufacturer [27], considering that the UAVs are responsible for sweeping rocket impact  
Figure 1: Impact area of a rocket launched from CLBI (Barreira do Inferno Launch Center). areas on launch missions aiming at the automatic detection of ships by aerial image processing. In offshore areas, it is not possible to use the Wi-Fi protocol due to limited area range and mobility between nodes of the aerial network. The ZigBee protocol is used by [PERSON] et al. [28], [PERSON] and [PERSON] [29] to perform fly-by-sensors (FBS) flight control with stable flight formation, while [PERSON] and [PERSON] [30] propose a UAV navigation system for dense urban areas in tunnels or indoor environments. The flight planning and formation model is discussed in [PERSON] et al. [31], [PERSON] et al. [32] where an effective routing protocol for navigation control and an information sharing system with onboard sensors and flight path formation algorithms are proposed for various UAVs. [PERSON] et al. [18] propose an optimized trajectory design to avoid restricted regions aiming at bypassing them through close preset landmarks.