## 4 Results
The total message count handled by the MSF since the ship began sailing is shown in Table 2. During the voyage, the periodic messages (TIM-222) transmitted by the CTDs with TIM SIMs are those received from the shore cells when the ship moved away from the port and when it skirted the Italian islands and peninsula within 12 miles. In contrast, the periodic messages transmitted by the CTDs with AZCOM SIM (AZCOM-999) are those transmitted by the shipboard network during the stretches when the radio base station could remain on. In particular, it can be observed that container 4B has never transmitted directly on the TIM terrestrial network, since the device with TIM SIM stopped working immediately, due to a malfunction. Container 1B has never transmitted directly on the AZCOM onboard network, since the device with AZCOM SIM did not work from the beginning. Overall messages transmitted via the BLE mesh network are a considerable number (from 15% to 85% of the total per container). Some asynchronous messages were also transmitted during navigation, mainly driven by the accelerometer for wave movements. A more in-depth analysis was conducted on the periodic messages published on the ICON platform. In fact, the payload of the synchronous messages contains not only the sensor values but also the timestamp of sending from the CTD and the value of the cellular signal strength detected by the modem in terms of the Received Signal Strength Indication (RSSI) [37]. Using these data, the following performance indicators were calculated for each scenario:  
* delay (s): arithmetic mean of the difference between receiving timestamp on ICON (\"ts\") and sending timestamp from CTD (\"time\"). * PL (packet loss): % of synchronous messages sent from CTD but not received from ICON. * RSSI (arbitrary units from 0 (\(-\)113 dBm or less) to 31 (\(-\)51 dBm or greater)): arithmetic mean of RSSI values for NB-IoT synchronous messages. The results are shown in Table 3. In the terrestrial and near-sea scenarios, the active cellular network is the TIM commercial network, while in the open-sea scenario, the active cellular network is the onboard AZCOM network with satellite backhauling. Thus, in the first case (terrestrial and near sea), CTDs with TIM SIMs transmit either in NB-IoT mode or in BLE M mode, while CTDs with AZCOM SIMs transmit only in BLE M mode. In the second case (open sea), conversely, CTDs with AZCOM SIMs transmit either in NB-IoT mode or in BLE M mode, while CTDs with TIM SIMs transmit only in BLE M mode. It should be pointed out that two CTDs with TIM SIMs transmitted messages only via BLE M, even when the commercial network was available; these are 1R and 4B. This is because the SIM provider recklessly deactivated them just close to the field trial. In addition, CTD 3B with TIM SIM turned off itself at the beginning of open-sea navigation. Finally, CTD 1B with AZCOM SIM did not work at all. \begin{table}
\begin{tabular}{c c c c c c c c c c} \hline \hline
**MessagesContainer** & **5R** & **4R** & **3R** & **2R** & **1R** & **5B** & **4B** & **3B** & **2B** & **1B** \\ \hline TIM-222 & 23 & 125 & 76 & 16 & OFF & NP & OFF & 7 & 15 & 18 \\ \hline
**AZCOM-999** & 108 & 93 & 96 & 99 & 31 & 101 & 81 & 102 & 77 & NP \\ \hline
**Bluetooth mesh** & 112 & 130 & 117 & 105 & 150 & 21 & 140 & 27 & 34 & 100 \\ \hline
**Asynchronous** & 8 & 16 & 54 & 8 & 8 & 28 & 12 & 12 & 11 & 0 \\ \hline
**Total** & 251 & 364 & 343 & 228 & 189 & 150 & 233 & 148 & 137 & 118 \\ \hline \hline \end{tabular}
\end{table} 
Table 2: Kinds of messages received from the MSF in navigation.