## 4 ITS Architecture Proposed for the FMCS
### FMCS Prototype Network Diagram  
After establishing the ITS architecture proposal for the FMCS, the scope of the prototype to be developed must be defined. A network diagram, with the modules selected for the prototype and the proposed communication technologies for the architecture, is presented in Figure 4. The prototype focuses on the three main modules of the architecture presented in Figure 3: TMC, ITS Roadway Equipment, and Transit Vehicle OBE. Figure 4 shows the path followed by the information between the different modules, and also shows module location. The OBE is located in each vehicle, which communicates with the ITS Roadway Equipment located in the city buildings, in which a gateway is located. \begin{table}
\begin{tabular}{c c c} \hline \hline
**Flow** & **Name** & **Description** \\ \hline A & Location data + Vehicle information + Public vehicle schedule performance & Measured parameters in vehicles. \\ \hline B & Location data + Vehicle information + Public vehicle schedule performance & The same information collected by the OBE is verified and passed to the Transit Center \\ \hline C & Public schedule info + Public operator info + Route + Alerts + Addressee & Assignment information to Transit Vehicle Support, this includes to identify the recipient. \\ \hline D & Public schedule info + Public operator info + Route + Alerts & Information on schedules and routes assigned to the corresponding vehicle that requests it. \\ \hline F & Public vehicle operator display & Information on the vehicle operator’s work parameters, such as the assigned route number, schedules for that route, and alerts. \\ \hline G & Public vehicle operator control & Manual interaction to operate the OBE device. \\ \hline H & Public vehicle operator input & Data the vehicle operator sends to the system. \\ \hline I & Route assignment + Vehicle assignment + Change alerts & Detailed information on the vehicle operator’s work parameters, also includes detailed alerts on work parameter changes. \\ \hline J & System information & Information generated each time the administrator has made a request to the system. \\ \hline K & System administrator input & Access parameters of the system administrator and information request. \\ \hline L & Public operation status + Traffic alerts + Suggestions & Information related to traffic alerts generated and suggestions for changes in routes and schedules. \\ \hline M & System Operator input & Input or access data for the system operator. \\ \hline N & Enterprise administrator input & Access parameters and requests information for the company administrator. \\ \hline O & Enterprise information + change request & Responses to requests made by the company administrator. \\ \hline P & Public vehicle data & Information related to different parameters measured and processed of the vehicles. \\ \hline Q & Traffic images + Road conditions + Incidents & Predefined messages sent by “Traffic Management Center” to detect different traffic conditions. \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Information flow of the ITS architecture proposed. The selected communication technology between Transit Vehicle OBE and ITS Roadway Equipment was LoRa, using the network protocol LoRaWAN. This was preferred over LoRa messages for two reasons. The first is that LoRaWAN provides an adequate security layer, the information is encrypted and the devices must join the network using the Over-the-Air Activation (OTAA) method in order to start sending messages. The join operation has several authentication parameters. The second reason is to avoid packet collision at the gateway (problem identified in the systematic review [14; 81; 82; 83]) as LoRaWAN network protocol facilitates the dynamic change of LoRa communication parameters to minimize the probability of packet collision. The use of the LoRaWAN network protocol requires the use of a LoRaWAN server, which is in charge of all the upper layers of communication; the proposed prototype uses The Things Network (TTN) platform [84].