## 2 IoT and UAVs in Sustainable Smart Farming
### IoT in Smart Farming
* Wireless connectivity technologies with medium distance range (10 to 100 m): This category includes ZigBee [16] and Wi-Fi [17] technologies. * Wireless connectivity technologies with a long-distance range (100 m and above): Cellular networks, and Low Power Wide Area (LPWA) technologies which are classified to Non-3 GPP (LoRa [18], Sigfox [19] and Weightless) and 3 GPP (NB-IoT [20], LTE-M, EC-GSM) technologies that are considered in the long-distance communication range category. Figure 2 is a graphical representation of the classification of communication technologies. Figure 1: The architecture of IoT. **Classifying Standards based on Communication Distance:** For short-range applications, IEEE 802.15.4-based protocols are the preferred choice [11], which are intended for Low-Power Wide-Area Networks (LPWANs). It offers a data rate between 20 kbps to 250 kbps, operates over different frequency bands such as 433 MHz, 868 MHz, 915 MHz and 2.4 GHz; and supports a maximum outdoor Line of Sight (LoS) range of 100 m [21]. On the contrary, IEEE 802.11 standard are suitable for applications that need medium range connectivity. The 2010 release of this standard, namely IEEE 802.11p, incorporate scenarios with a high mobility requirements. This particular release appears to be of large interest in agriculture scenarios because of it's large transmission range, maximal legal transmission power of 1 W, and the less interfered band of 5.9 GHz ISM frequency [9]. When coverage is concerned, long-range technologies are the only reliable and desired solutions. Cellular communication technologies such as 3G, 4G, Long Term Evolution (LTE), and 5G are most suitable and a reliable standard for precision agriculture, where a large amount real-time data needs to be transmitted and processed [22]. For instance, the data rate of LTE data rate is up to 3 Gbps for downlink and up to 500 Mbps for uplink, while the latency is than 10 ms in the LTE-Advanced Release 10 [9]. In addition, the 5G communication system is expected to provide real-time Device to Device (D2D) communication, which will enable vehicle positioning. Additionally, a huge number of devices can be supported per square kilometer [23]. In comparison to LTE, 5G can operate on higher frequency bands, and hence can offer wider channel bandwidths. Particularly for rural areas, 5G technology may enable new capabilities on farm equipment by offering higher data rates and longer transmission distances under the paradigm of real-time connectivity. However, the availability of the cellular network and the economical feasibility of 5G technology in rural areas is still a questionable concern. Figure 2: A classification of communication technologies used in Internet of Things (IoT) based Smart Farming. Among long-range communication technologies of IoT, IEEE 802.11 ah and LoRa/LoRaWAN are the most reliable. The first one is an amendment of the IEEE 802.11 family, which was published in 2017 to support IoT scenarios such as smart metering [9]. It uses 900 MHz license-exempt bands, provide wider coverage range and consumes lower energy compared to Bluetooth and IEEE 802.15.4. It provides connectivity to thousands of devices with a single access point up to one-kilometer radius of coverage. On the contrary, LoRaWAN is one of the most promising LPWAN specifications intended for a network of battery-operated wireless nodes. More information on LoRaWAN is provided in later sections. **Application layer:** The highest level of the IoT architecture is the application layer, where the benefits and utilities of IoT are most apparent. There are lots of intelligent platforms or systems in this layer for the purpose of monitoring and controlling of soil condition, water and nutrition level, plants and animals. This layers also supports the early warning and management of diseases and insect pests, infestation and agricultural product safety tractability; as a result, production efficiency can be improved.