## 4 Pilot System and Field Measurements Setup  
The pilot system and field measurements were carried out with ITS-G5 and 5 GTN networking capabilities, and the test measurements were conducted on the aforementioned test-track. The field measurements of the pilot system evaluate the capability of vehicular networking considering V2V and V2I scenarios supporting special road weather services. The pilot system for field measurements is equipped with the Road Weather Stations (RWS) and the 5 th generation Cohda MK5 On-Board Units (OBU) that is compatible with the ITS-G5 and Cohda MK6 OBU compatible to V2X applications providing the vehicle tracking, road traffic safety and efficiency. Both units have basically the same functionalities consisting of a Windows 7 workstation and Cohda Wireless MK5 transceivers tuned between 5.35 and 5.925 GHz, compatible with ITS-G5 (IEEE 802.11p) and V2X CTX-0800 OBU. The Cohda MK6 OBU is compatible with 5G and LTE bands together with the Global Navigation Satellite System (GNSS) feature. The configuration of the Cohda Wireless MK5 transceiver operates at a channel bandwidth of 20 MHz (10 MHz also available), designed on the 5.875-5.905 GHz band compatible with the ITS-G5 (IEEE 802.11p) and V2X OBUs. We used a SUNIT F-series vehicle PC (Sunit Oy, Kajani, Finland) for the user interface (UI) in vehicles during the pilot measurements. The PC integrates different modules between the telematics, windows, and display unit. It also provides a vehicle monitoring platform which enables the external vehicle sensors control. The configuration of the wireless transceiver units is as follows: operating band: 5.875-5.905 GHz and channel bandwidth of 20 MHz (10 MHz also available). The maximum data-rate of this channel operates is in the range 6-54 Mbps [12]. We expected to achieve the maximum attainable data rate, but the payload for the data packet (no framework) was restricted to 10 Mbps. The employed CTX-0800 OBU is compatible with 5G and LTE bands together with the GNSS feature. We used Iperf2 to transmit the UDP packets to the network, with a packet size of 1202 bytes and delay between packets set to 1 ms. The size of a data packet can be different, according to the requirements, and the specific packet size shows the standardized packet size of a road weather station. We used the standard transmit power of 21 dBm (in Europe) for packet transmission [13]. To receive and capture the UDP packets, we used the network protocol analyzer Wireshark. The analyzer gathers all the road weather and traffic information i.e., data packet capture time, average data-rate, average packet per second, average packet size, etc.). The analyzer also offers IO graphs, using which we can assess the captured data packet information as a time function. We used the network tool \"Wireshark 3.4.3\" to analyze the data packets on the network and transport layer of ITS reference layer model. For these field measurements, the test-track had no major traffic density or obstacles during the pilot system tailored along the test-track [13; 14]. We tailored the field measurements in three different setups to analyze the performance of the heterogeneous VN in a realistic operational environment. These three different field measurement setups provide deep insight into network behavior at different vehicle speeds. In the V2I scenarios, we used a vehicle equipped with the OBU passing an RWS at speeds of 30, 40, and 50 km/h. Figure 3 shows the test-track equipped with the RWSs and a 5G base station for the field tests [6]. The RWSs transmit the data packets to the vehicle and we used a data packet capture software to capture ana analyze the packets. In the V2V scenario, we drove two OBU-equipped vehicles in opposite directions at speeds of 30, 40, and 50 km/h (single vehicle). One of the vehicles transmitted data and the other vehicle received and captured the data. The first vehicle transmitted the data using only the OBU transmitter as a connection point with the second vehicle.