## 5 Pilot Field Measurements  
We started the pilot and field measurements of vehicular networking using the ITS-G5 network. While driving to the measurement area, we turned on the measuring devices, recorded the route and captured the packets. We conducted the field test measurements at three different speeds, namely 30, 40 and 50 km/h with an average speed of 40 km/h. The distance between cars was from 5 m to 200 m approximately. As shown in Figure 4, the connection between vehicles was on almost all the time and data rate stayed quite stable. The 1202 bytes of data packets were received with a 1 ms transmission delay. The average throughput during the field measurement was 1.36 Mbps.  
In the second scenario, we conducted the field measurements of vehicular networking using the 5G test network. During the test measurements, the speed was from 0 to 50 km/h (average speed 40 km/h) and the distance between cars was approximately from 5 m to 200 m. As depicted in Figure 5, the connection between vehicles was on almost all the time and the data rate remained quite stable, as in the previous case. The 1202 bytes of data packets were transmitted with a 1 ms transmission delay. The average throughput during the trip was 1.55 Mbps.  
Figure 4: Data rate of vehicular networking using ITS-G5.  
To calculate the range of heterogeneous networking, we used a Python software where the RWS transmits the data to the nearby passing vehicle, as illustrated in Table 1. To calculate the range, we used Equation (5) by considering that the RWSs distributed the up-to-date road weather data to the nearby passing vehicles. The differences between ranges, calculated from the Wireshark measurements, were \(\pm\)42 m. Figure 6 shows that the connections were established between 220 m and 480 m before the RWS and lost between 380 m and 630 m after the RWS. The lengths of the connections were from 710 m to 930 m for the considered 5 GTN and ITS-G5 networks. The ideal situation for the communication link availability time was calculated according to (5), although the availability of a heterogeneous network has a relation between the ideal situation and the real-time field measurements [15; 16].  
The maximum range of the RWS (m) estimate was calculated as:  
\[Range=\frac{speed*\frac{\frac{measured\,\,Test\,\,drive\,\,length}{60}}}{2}, \tag{5}\]  
Figure 5: Data rate of vehicular networking using 5 GTN.  
Figure 6: RWS communication range (m) on a test-track in Vehicle-to-Infrastructure communication (V2I) using heterogeneous networking.  
where _speed_ is given in km/h and _measured test drive length_ is given in s.  
In Figure 7a, we can see the UDP packet capture from RWS-1 and in Figure 7b we can see the UDP packet capture RWS-2, respectively. Both RWSs were implemented with ITS-G5 technology. The yellow spots represent the UDP packet capture during field measurements tailored on the test-track. Furthermore, vehicles encountering each other exchanged their latest road weather information received from the RWSs. Figure 7 reveals that there were some points where the connection was lost in V2V and V2I scenarios, and this ultimately affected the average throughput.  
In Figure 8a, the range of 5 GTN packet capture during pilot measurements is shown together for the heterogeneous (ITS-G5 and 5 GTN) network. Figure 8a shows that the 5 GTN supported a greater range than ITS-G5 on the test-track for vehicular networking. The UDP packet capture in heterogeneous networking in Figure 8b illustrates that the network coverage and performance was enhanced in the field measurements. The yellow spots represent the UDP packet capture during field measurements tailored on the test-track. The missing yellow spots indicate the positions where data packets were lost.