# A Novel SDWSN-Based Testbed for IoT Smart Applications
## 3 System Model
### WSN Physical Network Setup for Node Distribution on the Ground  
The TI CC1352R can be used for physical network implementation in a variety of applications to allow for sensor node functionality to be modified over the air via cellphone configurability to change some module settings such as bitrate, capture rate, packet size, polling intervals, power, and so on, or to change the entire functionality of a sensor node. The physical network system is softwarized and implemented using LaunchPad SensorTag CC1352R and development boards, as well as Raspberry Pi (RPi). The LaunchPad modules contain a dual-band, low-power radio kit that allows for the coexistence of 15.4 Stack and Bluetooth Low Energy (BLE) on a single chip. The 15.4 Stack is an IEEE 802.15.4e/g RF communication stack that supports star topology networks in either sub-1 GHz (868 MHz /915 MHz) or 2.4 GHz applications. The sub-1 GHz 15.4 Stack is used for ground network connectivity in this paper. The motivation behind this is that the sub-1 GHz version offers numerous advantages, including longer range and improved in-band interference prevention, as well as the ability to broadcast BLE beacon packets while running on a sub-1 GHz 15.4 Stack network in dual-band mode.  
The proposed physical ground network topology with the intended dual-band communication functionality is depicted in Figure 16.  
\begin{table}
\begin{tabular}{c c c} \hline \hline
**RF Transmission Power** & **RSSI Values (dBm) for** & **RSSI Values (dBm) for** \\  & **Indoor Scenario** & **Outdoor Scenario** \\ \hline  & \(-69\) & \(-86\) \\
22 dBm & \(-71\) & \(-86\) \\  & \(-67\) & \(-87\) \\ \hline  & \(-52\) & \(-72\) \\
7.5 dBm & \(-55\) & \(-78\) \\  & \(-55\) & \(-78\) \\ \hline \hline \end{tabular}
\end{table}
Table 1: Transmission power impact on RSSI indoor and outdoor scenarios.  
\begin{table}
\begin{tabular}{c c} \hline \hline
**RSSI Values of the Departed Node (dBm)** & **Distance of the Node Moving Away (m)** \\ \hline \(-72\) & \(8\) \\ \(-80\) & \(9\) \\ \(-88\) & \(11\) \\ \(-92\) & \(13\) \\ \(-94\) & \(14\) \\ \hline \hline \end{tabular}
\end{table}
Table 2: RSSI measurements of node movement collected with relation to distance.  
The LaunchPad SensorTag CC1352 Rs are configured with leaf node firmware, which enables the modules to sense and transmit sensing data to the upper-level coordinators (CC1352R development boards). The gateway nodes are Raspberry Pis with CC1352R development boards connected. The development boards are configured with \"Collector firmware\" to collect the sensing data from the leaf nodes, while the Raspberry Pi is used for data storage and buffering and is connected to the development board using a USB cable. This physical network topology design has the advantage of enabling dual-band connectivity, allowing the client to reconfigure each physical node using over-the-air debugging (OAD) functionality, which aligns with the softwarization concept. As a result, this network design not only allows for reconfigurability of ground network entities, but it also allows for regular data collection from the ground network within the central RPi station.