# Smart Irrigation Systems from Cyber-Physical Perspective: State of Art and Future Directions
## 3 Problem Space
### IoT Layer Dimension
#### 3.1.2 Network Layer  
The network layer establishes communication between IoT devices or devices to servers or from devices to clouds. According to our findings, WiFi has been widely adopted into embedded systems such as Arduino Uno or NodeMCU, providing a seamless foundation for direct utilization. The use of Wireless Sensor Networks (WSNs) in rural areas is highlighted by several studies ([PERSON] et al., 2018; [PERSON] et al., 2018; [PERSON] et al., 2018). WSNs consist of three primary topologies: star, cluster tree, and mesh. With a range of up to 4000 m and low-power consumption, WSNs  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Brand** & **Model** & **Open** & **Paper ID** & **Embedded** & **Strengths** & **Limitations** \\  & & **Source** & & **Wireless Module** & & **Expandable I/O pins. Wide** & Only WiFi \\ Arduino & Uno & Yes & 41,44,45,47,50,51,54, & WiFi & & range of code libraries. & module \\  & & & 56,57 & & Cost-effective. & & embedded. \\ \hline Raspberry & Pi & No & [32,37,46,52,58,64] & WiFi & & & & Only WiFi \\ Pi & & No & [32,37,46,52,58,64] & WiFi & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline Espressif & NodeMCU & & & & & & \\  & & & & & & & \\  & & & & & & & \\  & & & & & & & \\ \hline Pycom & LoPy4 & Yes & [43] & LoRaWAN, Sigfox, WiFi, Bluetooth & & & & \\  & & & & & & \\  & & & & & & \\ \hline \hline \end{tabular}
\end{table}
Table 3: Microcontroller for IoT irrigation system.  
are particularly suitable for smart irrigation systems [67; 68]. Depending on the deployment environment, WSNs can be classified into terrestrial, underwater, mobile, and other types [67]. In smart irrigation, terrestrial, underground, and mobile WSNs are preferred for their cost-effectiveness, ease of implementation, and straightforward management. Table 4 compares different types of wireless technologies used in irrigation systems.  
One challenge with Wireless Sensor Networks (WSNs) is their limited energy, which can lead to network malfunctions [67]. While power banks can alleviate this issue, they require frequent replacements or recharges, which compromises system flexibility and portability. Alternatively, setting up charging stations offers a solution but involves additional investments and maintenance, adding complexity [67]. Utilizing natural energy sources such as solar panels is a viable approach to overcome these challenges, supporting WSN sustainability [44; 45; 47].  
LoRa, a low-power Wide Area Network (LPWAN) standard, is particularly suited for large-scale irrigation on farms due to its cost-effectiveness, long-range capabilities, no-operator infrastructure, and use of unlicensed spectrum [3]. In urban areas, LoRa coverage reaches up to 3 miles, extending to 10 miles in rural settings, making it ideal for transmitting small data packets like text messages. Comparatively, another WAN technology, NB-IoT, also provides long-distance coverage and offers quality of service (QoS) and reliable message delivery. However, LoRaWAN has enhanced battery life in comparative tests [3; 37; 69].  
Table 5 illustrates the paper related to wireless technology in the irrigation system.