# Communication Interface Manager for Improving Performance of Heterogeneous UAV Networks
## 3 Architecture of the Interface Manager  
This section presents the architecture of the proposed interface manager (IM), which aims to provide heterogeneous communication in networks composed of multiple UAVs. Figure 1 illustrates the layers of the proposed architecture.  
According to [5], each UAV that belongs to a multi-UAV system needs to communicate while meeting some requirements: observing the environment, evaluating their own observations and those received from other UAVs, reasoning from the observations, and acting in an effective way. Thereby, each layer illustrated in Figure 1 meets one of these requirements, as further detailed.  
* Application: In this layer, the mission of each UAV is defined. This includes the definition of trajectories, their mobility features, their goals, the type of messages that will be transmitted by each UAV, the recipients, and their payload. In addition, other details are defined in this layer such as the frequency of sending, definition of the protocol used for routing, and packet size. This layer can synchronize with other applications, in our case, with the NS-3 network simulator and the Gazebo virtual environment.
* Processing: This layer is responsible for executing systems, mechanisms, reasoning or decision-making entities, and coordinating systems. More specifically, it is responsible for the number of vehicles (nodes) in the network, the amount of interfaces, analyzing  
Figure 1: Interface manager (IM) architecture.  
the parameters sensed by the medium, and calculating other parameters or conditions. Such parameters are used as the input of the decision-making process. This layer evaluates the parameters received from the sensing layer composed by its own and other sensing nodes to define the interface that will improve the link. To ensure a fair decision, it is necessary to use parameters common to all employed wireless interfaces. Sensing (PHY): This layer is responsible for sensing medium information and metrics (signal strength, background noise, latency, throughput, packet loss, and quantities of sent and received bytes). In the proposed architecture, periodic beacon frames are transmitted to allow calculation of the desired metrics.  
In summary, the sensing layer serves to \"listen\" to the medium to sense the network parameters of interest. The protocol layer is used to enable each interface to calculate and sense such parameters according to their intrinsic characteristics of frequency, range, bandwidth, and transfer rates. Although one interface is chosen for communication, the other(s) remain in a listening state to maintain dynamic sensing. The processing layer uses the collect data to execute a heuristic, which aims to select the best interface to be used at a given moment. Finally, the application layer defines the UAV mission, which includes the messages to be sent by each UAVs. It also details the UAV mobility characteristics, such speed, acceleration, deceleration, and waypoints. The protocol layer and the sensing layer can be considered as modules that support the addition of other wireless interface cards to the system.  
To guarantee the survivability of an ad hoc network, each node needs to be connected with at least one neighbor through a strong link with acceptable data flow. The aim of this method is to establish the reliable exchange of messages with the maximum possible QoS and to perform the maximum number of successful packet deliveries.