## 2 IoT and UAVs in Sustainable Smart Farming
### IoT in Smart Farming  
There are some important components of Agricultural IoT (AIoT), such as sensor equipped devices, internet connectivity, wireless communication technology, sensed and transmitted data, etc. The wireless communication technology plays a pivotal role in the successful deployment of IoT systems, which can be categorized based on spectrum, transmission distance, and application scenarios. As shown in Figure 1, the structure of IoT is primarily based on three layers; namely, the perception layer where the sensing is done, the network layer which deals with data transfer, and the application layer where data storage and data manipulation is done [5]. **Perception layer:** The perception layer consists of various terminal devices, sensors, Wireless Sensor Networks (WSN), RFID tags and readers, Near Field Communications (NFC) devices, etc. [11]. At this layer, sensors are used to collect information about temperature, wind speed, humidity, nutrient level, plant diseases, insect pests, etc. The collected information is being processed through embedded devices and are uploaded to a higher layer through the network layer for further processing and analysis. These terminal devices and sensors are used to monitor, control, identify and track agricultural and livestock products. For instance, WSNs are often used to climate control and monitoring of storage and logistics facilities [11]. On the other hand, RFID technologies are the most crucial example of interconnected devices. RFID tags store data in the form of the Electronic Product Code (EPC), which are then read, triggered and manipulated by RFID Readers [12]. \begin{table}
\begin{tabular}{c c} \hline \hline
**Acronym** & **Definition** \\ \hline
3 GPP & 3 rd Generation Partnership Project \\ AI & Artificial Intelligence \\ AIoT & Agricultural IoT \\ BPSK & Binary Phase Shif Keying \\ GCS & Ground control station \\ IoT & Internet of Things \\ LPWAN & Low Power Wide Area Network \\ LOS & Line of Sight \\ LoRa & Long Range \\ LoRaWAN & Long Range Wide Area Network \\ M2M & Machine to machine \\ NFC & Near Field Communication \\ NBIoT & Narrow Band IoT \\ QoS & Quality of Service \\ RFID & Radio Frequency IDentification \\ UAV & Unmanned Aerial Vehicle \\ UNB & Ultra Narrow Band \\ UWB & Ultra WideBand \\ WSN & Wireless Sensor Network \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Acronyms used in this paper. Hence, by offering object identification, tracking and data storage on active or passive tags; WSN, RFID and NFC technologies play an important role in the agricultural domain. **Network Layer:** In this paper, we focus on the network layer of IoT where the sensors and devices need to be connected to their neighbouring nodes and a gateway in order to build a network. At this layer, the sensor nodes interact and communicate with other nodes and gateways within a network in order to forward data towards a remote infrastructure; where these data are stored, further analysed, processed and disseminated to useful information [13]. A large scientific literature has been conducted on wireless networks, addressing several problems, such as reducing energy consumption, improving networking features, increasing scalability and robustness [11]; however, the connectivity limitations in remote areas have not been addressed extensively. Wireless protocols and standards sets the protocol for wireless communication. For instance, IEEE 802.15.4 is a wireless standard which facilitate the interconnection between internet-enabled gateways and end-nodes. A few other examples of such protocols are ZigBee, Sigfox, ONE-NET, WirelessHART, ISA100.11a, LoRaWAN, Bluetooth Low Energy (BLE), DASH7, etc. [14]. These standards are categorized in terms of transmission distances as follows [15]:  
* Wireless connectivity technologies with short-distance communication range (at most 10 m): Examples include Bluetooth, RFID, UWB technologies [15].