# Spectral and Energy Efficiency Trade-Off in UAV-Based Olive Irrigation Systems
## 2 Method
### Architecture of the Proposed UAV-Based Olive Irrigation System  
This research deploys a network model with a three-layered architecture, as shown in Figure 1. The uppermost layer represents the cloud layer; the middle layer is referred to as the fog layer; finally, the lower layer is composed of IoT or smart devices. A three-layered network model is a prevalent architecture in the Industry 5.0 paradigm, which has gained significant global traction as a fundamental driver of industrial growth and transformation.  
Figure 1: Architecture of the proposed UAV-based olive irrigation system.  
* The topmost layer is the cloud layer, consisting of a cloud storage node and a cloud data center. The cloud layer provides scalability and resilience for storing and processing large amounts of data. It serves as a centralized storage unit for updated information on the behaviors of various IoT devices (UAVs and actuators). Additionally, the IoT devices in the lower layer receive regular updates from the cloud layer, ensuring that their behavior is up-to-date. Additionally, the user/farmer can instantaneously and remotely visualize (via the internet) the information and running activities of the olive farm. The user can also control the UAV movements around the orchard.
* The intermediate layer is called the fog layer, consisting of fog nodes (it can be based on Raspberry Pi, Arduino, or any micro-controller) for data processing and storage. It is designed to provide low latency and efficient processing power to meet the needs of the applications running on the devices in the lower layer. These nodes offer services to nearby IoT devices and maintain timely behavior records. This intermediate layer acts as a bridge between different IoT systems and the cloud layer, thus facilitating the interoperability of IoT systems. A cloud gateway (CG) connects the fog layer to the upper layer. Communication between the fog layer and the lower/upper layer is facilitated through M-MIMO technology (see Figure 2).
* The lower layer, also known as the IoT or smart device layer, consists of drones and actuators. In this layer, drones are equipped with cameras and onboard sensors. Specifically, these vehicles ensure remote sensing (RS), which offers the advantage of collecting vital information on a large temporal and spatial scale (which cannot be achieved with traditional technologies). Indeed, by flying over fields, the drones measure soil conditions, namely temperature, humidity, light, soil moisture, and nutrient levels. UAVs can also monitor crop health, detect anomalies, and respond to all end-user requests. As mentioned earlier, IoT devices in this layer have limited storage and computational capacity. Therefore, UAVs send a substantial amount of collected data to the fog layer to conduct speedy computation and services. Then, according to the obtained results, the fog nodes communicate with actuator devices (placed directly in the soil beside each olive tree) to activate/deactivate the corresponding solenoid valve that irrigates the olive tree.  
Figure 2: Network model of the proposed UAV-based olive irrigation system.