## 9 Results and Discussion
### Results of the SWORD Algorithm  
The application of the _SWORD_ algorithm depends on soil moisture measurements. Air temperature, air humidity, and soil moisture are measured by the sensor node of the WAS. Figure 14: Estimated battery life versus battery capacity in the WAS based on the sleep/wake scheme and in the traditional operation. Figure 13: Developed power savings of the WSN nodes based on the sleep/wake scheme. Experiments are conducted several times on different days between June 2018 and July 2018 to measure the climate conditions in the farm. However, the measurements (Figure 15) performed on 8 July 2018 are considered in this study to verify the performance of the proposed _SWORD_ algorithm because the weather conditions on that day are harsh (e.g., high air temperature and low soil humidity) in the considered area. The measurements are configured to capture data every 15 min, as seen in the timing diagram of the sleep/wake scheme in Figure 6. The sensor node transmits the climate conditions to the coordinator node every 15 min via the router and main router nodes. In this case, 96 samples (from 4 samples every hour) are collected in a day (Figure 15). The _SWORD_ algorithm checks whether the measured data regarding soil moisture are redundant. When the difference between the preceding and subsequent soil moisture measurements is zero or less than or equal to 5%, the data are not transmitted to the router node. Otherwise, the data are transmitted to the router node. The transmitted data are minimized through this strategy. Thus, the power consumption of the sensor node is considerably improved relative to the sleep/wake scheme and traditional operation. In the _SWORD_ algorithm, the transmitted data from the sensor node to the router node are minimized to 13 samples, as shown in Figure 16. Soil moisture measurements are weighted within the range of 45-75%. The reading range of 45-49% denotes dry soil, 50-55% represents moderate moist or field capacity, and 55-75% indicates wet or saturated soil. The _SWORD_ algorithm minimizes data transmission (_data_tx_) by 86.45% relative to the sleep/wake scheme, as obtained using Equation (18):  
\[Minimization_{data\_tx}=\left(1-\frac{samples\ based\ on\ SWORD\ algorithm}{samples\ based\ on\ sleep/wake\ scheme}\right)\ \times\ 100\% \tag{18}\]  
Therefore, the average current consumption of the sensor node is remarkably improved to 0.1 mA by applying Equation (19). In this case, a power consumption of 0.74 mW can be dissipated during the transmission of climate conditions in the sensor node based on the _SWORD_ algorithm:  
\[I_{SN\_avg\_SWORD}=I_{SN\_avg}\ -\ \left(\frac{Minimization_{data\_tx}}{100} \right)\ \times\ I_{SN\_avg}, \tag{19}\]  
where \(I_{SN\_avg}\) is the average current consumption of 0.731 mA of the sensor node, which is previously computed using Equation (7) based on the application of the sleep/wake scheme. Figure 15: Measured and transmitted data about climate conditions from the sensor node to the router node. Consequently, battery life can be prolonged to 1093 days (3 years) by applying Equation (11) and using the same battery capacity of the sensor node (i.e., 7.4/2600 mAh). The battery life for a particular energy of the battery at the current usage of the sensor node is estimated in the relationship shown in Figure 17. The figure indicates that the power savings of the sensor node based on the _SWORD_ algorithm considerably improve battery life to 86.45% and 99.48% relative to the sleep/wake scheme and traditional operation, respectively. However, these percentages may increase or decrease depending on the weather, soil conditions, and farm location. As weather temperature increases, soil condition changes rapidly from moisturized to dehydrated, thereby remarkably changing soil moisture measurements. Data transmission can occur, and power consumption increases. By contrast, data transmission and power consumption are considerably minimized when soil moisture is constant under good weather or rainfall conditions.