# Cooperative UAV Scheme for Enhancing Video Transmission and Global Network Energy Efficiency
## 4 Evaluation
### Simulation Description and Metrics  
We implemented the VOEI protocol on the Mobile Multi-Media Wireless Sensor Network (M3 WSN) OMNeT++ framework [26]. M3 WSN framework implements the full network stack for FANET communications, including the physical, MAC, routing, and application layers, as well as the energy consumption and mobility, following the network and system model introduced in Section 3.1. We conducted 33 simulation runs with different randomly generated seeds, and the results show the values with a confidence interval of 95%. The simulations last for 1000 seconds (s) and run with the lognormal shadowing path loss model. We set the simulation parameters to allow wireless channel temporal variations, link asymmetry, and irregular radio ranges, as expected in a real FANET scenario. We consider a FANET scenario composed of 35 UAVs, where 29 UAVs are flying following the PPRZM [22] over the entire flat terrain of 200 \(\times\) 200 m [5] to explore and disseminate live video streaming from the environment. Such UAVs are flying with different speed limit intervals: (i) 1 to 5 m/s; (ii) 5 to 10 m/s; (iii) 10 to 15 m/s; (iv) 15 to 20 m/s. As expected in FANET multimedia applications such as safety and security, environmental monitoring, and natural disaster recovery, we have one fixed Destination Node (\(DN\)) located at \((100,0)\)[14]. We consider one UAV located at \((100,100)\), working as controller node \(CN\), to periodically collect UAV information and send configuration commands. In addition, we have four UAVs responsible only for forwarding a control message for the central controller (\(CN\)). Furthermore, all UAV nodes are equipped with IEEE 802.11g [16; 17]. The transmission power is set to 12 dBm, resulting in a nominal \(R_{max}\) of 55 meters. Based on the simulation area and \(R_{max}\), videos are received at the \(DN\) via one to four relay nodes \(RN_{i}\), depending on the routing protocol routing protocol, and also the source node location. It is important to highlight that video transmission over ad hoc networks with high number of hops suffer of high packet loss ratio, while reducing the QoE [27]. Each UAV is equipped with a battery with an initial energy of 18,720 Joules. In the simulation, UAVs rely on the Carrier Sense Multiple Access with Collision Avoidance (CSMA/CA) protocol for Medium Access Control (MAC) layer, without using Request to Send/Clear to Send (RTS/CTS) messages and retransmissions. In case of buffer overflow, UAVs consider a drop tail mechanism to drop packets. At the application layer, UAVs take into account a QoE-aware redundancy mechanism to add redundant packets only to priority frames [5]. We have conducted simulations with two setups: SD-UAVNet and VOEI protocol. Particularly, SD-UAVNet considers the SDN paradigm applied to FANET, where the controller node considers the global UAV context information to establish the route data path with relay location optimization without considering energy for decision-making [11]. On the other hand, VOEI protocol performs all decision-making in a controller by taking into account energy issues in order to provide energy-efficiency operation, such as introduced in Section 3. We scheduled a random event at a different location, and when a given UAV detects such event, it starts to capture and disseminate a video about the event. We considered video sequences with different video features downloaded from the YUV video trace library and YouTube [28], i.e., Container, UAV\({}_{1}\), and UAV\({}_{2}\). We consider videos with different features since small differences in motion and complexities level can influence the obtained QoE values [29; 30]. Specifically, the Container video has similar characteristics as a UAV hovering in a given area to capture the video, which means that there is a small moving region of interest on a static background.