## 4 Hardware Implementation  
In this section, we will discuss the importance of customization of sensor node and gateway for real-time monitoring of the filling status of the bins. Here, the sensor node and gateway are developed based on LoRa modulation; additionally, the gateway is integrated with ESP 8266 Wi-Fi module for transmitting data over the internet. In the initial stage of designing the nodes, the power consumption parameter is the key as the nodes are installed in an outdoor environment where the electrical grid network should not be utilized for powering the nodes because it increases the infrastructure cost for installing a separate electric grid network. The power consumption parameter is the key in the initial stage of designing the node, as the nodes are meant to be installed in an outdoor environment where the electrical grid network cannot be used to power the nodes because it raises the cost of infrastructure for installing separate electric grid network. Concerning powering the sensor node, we embedded the power jack for supplying power to the node through batteries. The sensor node and gateway are integrating with the +5 V and +3.3 V voltage converter to supply the appropriate voltage. As discussed earlier in recent studies, the selection of a communication module plays a critical role in preventing the power dissipation in the nodes during transmission of the data. So, communication module is chosen with low power consumption for transmitting the data to long-range. Another major component that is taken into account for designing the node is the computing unit. The computing unit is chosen based on computational power that is a criterion for processing the acquisition data. In our case, the computing power for processing the acquired data is of low complexity because the main objective of our study is to senses the filling data. Selecting the appropriate microcontroller/micoprocessor is also a vital parameter for developing an energy-efficient node. After the completion of choosing suitable components for designing the node, the next stage is subjected to integrating all these components on the single board for executing a flexible, reliable, and compatible node. Figure 2 illustrates the block diagram, PCB layout, and prototype of the sensor node. The node is embedding with an Atmega 328P controller and SX 1278 LoRa transceiver. In our study, the complexity of processing the data is low, we preferred the Atmega328P controller for computing the data as it consumes the least amount of current around milliamperes (mA). Here, we estimated the amount of battery required for the sensor node from Reference [34]. The sensor node sends data for every 30 min with airtime of 78.08 ms for 25-byte payload with SF7 and 125 BW. Therefore, to perform one transmission by the sensor node, it consumes 1.0962 mA of energy. If we had a battery of 2000 mAh of capacity, we could perform 1824 transmissions, i.e., performing 48 transmission per day (one transmission for every 30 min interval). With respect to battery capacity of 2000 mAh, the sensor node remains active for 38 days. If we place the battery capacity of 20,000 mAh, the sensor node performs the 18,240 transmission and the sensor node remains active for 380 days. The technical specifications of the Atmega328P microcontroller and SX1278 LoRa module are detailed in Tables 1 and 2. Figure 3 illustrates the block diagram, schematic view, and prototype of the LoRa-based gateway. An Atmega 328P controller is built into the gateway, SX 1278 LoRa transceiver, and ESP 8266 Wi-Fi module. The objective of the gateway is for transmitting the data over multiple communication protocols, in this SX 1278 LoRa transceiver receives the data, the Atmega 328P controller triggers the ESP 8266 Wi-Fi for transmitting the data over internet protocol (IP). The technical specifications of ESP 8266 Wi-Fi are shown in Table 3.