## 4 Evaluation
### Scenario  
Figure 3 depicts the implemented and deployed architecture in a Colombian Coffee Smart Farm, introduced in Section 3.2. This network aims at providing reliable data for coffee farm services such as watering, fertilizing, harvesting, and forecasting production. The farmers make important decisions to increase their earnings based on the data collected and the information obtained by such services; the quality of historical data, such as temperature, is crucial to their Accuracy. Farmers need to trust in the information offered by services; therefore, it is pivotal to achieve high data reliability.  
The Things Tier includes devices such as sensors of temperature, humidity, light, and moisture. The sensors cover three hectares of a coffee crop, the coffee processing center, and the coffee storage center. In particular, this tier comprises: (i) a weather station Smart Agriculture PRO from Libelium-Waspmote Plug and Sense! [51] with external solar panels, which supports several radio technologies (ZigBee, Wi-Fi, 4G, SigFox, LoRaWAN) and sensors for monitoring soil moisture, solar radiation, atmospheric pressure, pluviometer, air temperature, and air humidity. This station covers all the three coffee farm hectares. (ii) a Datalog X-PRO from OMICRON [52] with an Internal rechargeable battery, which supports Wi-Fi, SigFox and 3G, and sensors for soil moisture, air temperature, and air humidity. This Omicron device operates in just one of the hectares of the coffee farm. (iii) sets of new low-cost sensor-tags from INTEL that support BlueTooth Low Energy, ZigBee, and Wi-Fi sensors for temperature and humidity. A set operates in each hectares of the coffee crop. The primary communication protocol used at the Things Tier was IEEE 802.11n (i.e., IEEE 802.11x, IEEE 802.11 b, and IEEE 802.15.4) because it is the protocol supported by all the IoT devices deployed in the case study farm. Using IEEE 802.11 is not necessary to pay for a subscription, such as with SigFox or 3G/4G.  
The Fog Tier includes an FN per hectares and a Fog Controller. In this case study, a single Fog Controller and three FNs were used due to the farm extension and the few IoT devices generating data. FN collects data from the Things Tier and runs FDM and FRM for providing reliable data to the Fog Controller; each FN functions on an ESP32 module and a Raspberry Pi 3 Model B with integrated Wi-Fi and Bluetooth connectivity. FNs are separated between 80 and 100 m (approximately) from each other. The Fog Controller Node runs on a Raspberry Pi 4 Model B that manages and processes the farm information. The Fog Tier communicates with the others using a REST-based services style by  
Figure 2: Data cleaning mechanisms to provide reliability.  
the HTTP protocol; it was necessary to use a standardized north interface that would allow simple interaction with the Cloud. This node sends aggregated information to the Private Cloud Tier that performs an in-depth analysis of the information provided by lower tiers via a Linux VPS server over Hyper-V. This server offers the following farm services: environmental variables monitoring, historic coffee production, production forecast, and IoT infrastructure management.