## 3 Proposed Architecture
### Network Architecture  
This section presents the mechanism of establishing the communication between the sensor nodes (detection end device) and coordinator (monitoring end device). Moreover, the communication establishment of sensor node and coordinator are also detailed presented. The security that is implemented in the network is also clearly presented, including interference of the communication network. (a) Communication:  
Figure 3: Schematic representation of detection end device placement. In this section, we present the wireless link of the different components present in Figure 4. The wireless links are represented in the dash links and different colors are assigned to the dash links for recognizing the type of wireless communication. The black color dash line is for 2.4 GHz RF communication, and the red color dash line is for LoRa communication. A 2.4 GHz-based ZigBee communication module is available for detection of end devices and monitoring end devices. In our study, we are aiming to utilize point-to-point communication for the implementation of the proposed system, where the sensor nodes (detection end device) only communicate with the corresponding allotted adjacent sensory node (detection end device). Moreover, a hopping data sharing mechanism is used, where the sensory node that is least distance from the coordinator (Monitoring end device) communicates all the data from the other nodes with the coordinator (Monitoring end device) which means that the node will be the single point of contact for the allotted sensory nodes with the coordinator as shown in the Figure 4.  
As shown in Figure 5 of the proposed system, two communication modules were used, i.e., Zigbee and LoRa. Both the modules are chosen for their corresponding transmission properties suitable for the specific type of conditions and scenarios of application. For example, ZigBee (2.4 GHz) is more preferably used for data with lengthy packet sizes and applications requiring high data rate communication, while compromising the data communication distance limit. Similarly, LoRa (433 MHz in India) is preferably used for communication to longer distances while compromising the data size and length. In our system, the main computing unit uses the integrated ZigBee module through UART communication protocol to collect data from local nodes deployed at nearby places with more immunity to data loss. It then processes the received data to clean and format it into suitable packets and then it uses the integrated LoRa module through SPI communication protocol to transmit the formed packets to an allotted gateway that is presumably deployed at a long distance from the node. 1. Security  
During the deployment stage, we use AVR series of microcontrollers for applications similar to the current proposed one. In AVR using time complex or memory, complex algorithms are like a curse, because many times they convert the executing code into a blocking one which means during that process any other routine to be executed by the controlled is blocked and may cause interruptions in performing the desired function. Keeping these into considerations, we have to be very careful while using cryptographic algorithms in these low-bit controllers. Cryptographic functions such as AVR-Crypto, XXTea can be used for implementing encryption methodology. In our case, we have used  
Figure 4: Point-to-point communication of ZigBee enabled sensor node. the XXTea cipher functions for implementing symmetric encryption with private keys that remains unique for a different level of network nodes for enhanced security during data communication.