# Use of Wireless Sensor Networks for Area-Based Speed Control and Traffic Monitoring
## 4 LoRaWAN Area-Based Speed Control
### Estimating the Required Number of System Components  
An operational assessment of the proposed solution will be possible after determining not only the types of its components but, above all, their quantity. While defining the  
Figure 3: Road system in the Stare Babice commune (source: authors’ own image based on [61]).  
number of network servers (NSs) and application servers (ASs) is not problematic (one NS and one AS are sufficient for a specific task), the high number of gateways (GWs) and end nodes (ENs) requires careful analysis and direct reference to the specified control area. The operating radius (transmission range) will have a significant impact in the case of gateways. In contrast, for end nodes, the determining factor is the road length.  
The minimum number of gateways can be estimated using Relationship (2).  
\[N_{\text{GW}}=\left[\frac{X}{2*R}\right]*\left[\frac{Y}{2*R}\right] \tag{2}\]  
where  
\(N_{\text{GW}}\) is the number of gateways;  
\(R\) is the gateway transmission radius [km];  
\(X\), \(Y\) are the area dimensions [km].  
The number of end nodes can be estimated from Relationship (3).  
\[N_{EN}=\left[\frac{D}{d}\right] \tag{3}\]  
where  
\(N_{EN}\) is the number of end nodes;  
\(D\) is the total road length within the system-covered area [km];  
\(d\) is the distance between sensors [km].  
For the adopted area dimensions (14 km \(\times\) 6 km), the number of required gateways varies depending on the gateway transmission coverage radius, ranging from one gateway (for a radius R = 7 km or more) to 21 gateways (for a radius R = 1 km). The data are presented in Table 1.  
The total length of district and provincial roads within the designated area is approximately 45 km. This value should be expanded to include local roads, the quality of which is sufficient to pose traffic safety hazards due to significant vehicle speeding. The length of these roads is estimated to be more than 15 km, which, after rounding up, gives a total road length within the system-covered area of D = 60 km. This allows for determining the required number of end nodes based on the distance between sensors \(d\). The results are shown in Table 2.  
Please note that an excessive distance between the sensors will undermine the system's effectiveness and fail to provide a comprehensive picture of the traffic situation in terms of road safety. The best results will be obtained with a relatively short distance between the sensors. However, reducing this distance increases the number of sensors required, thereby increasing the deployment costs of the solution. For this reason, the distance \(d\) should be minimized while still maintaining the system's ability to perform its intended task. Consequently, the distance \(d\) was set at 200 m, which translates to a required number of  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline R = 1 & R = 2 & R = 3 & R = 4 & R = 5 & R = 6 & R = 7 & R = 8 \\ \hline
21 & 8 & 3 & 2 & 2 & 2 & 1 & 1 \\ \hline \end{tabular} (Source: authors’ own study).  
\end{table}
Table 1: Minimum number of gateways N\({}_{\text{GW}}\) depending on transmission radius R.  
\begin{table}
\begin{tabular}{c c c c c c c c c} \hline
**d = 100** & **d = 200** & **d = 300** & **d = 400** & **d = 500** & **d = 600** & **d = 700** & **d = 800** & **d = 900** \\ \hline
600 & 300 & 200 & 150 & 120 & 100 & 86 & 75 & 67 \\ \hline \end{tabular} (Source: authors’ own study).  
\end{table}
Table 2: Minimum number of end nodes N\({}_{\text{EN}}\) depending on the distance between sensors d.  
sensors \(N_{EN}\) = 300 units. It should be emphasized that, relative to LoRaWAN\({}^{\prime}\)s capabilities, this number is small and may raise concerns only in relation to the costs of deploying the proposed solution, not its functional effectiveness.