# A Methodology for the Design of Application-Specific Cyber-Physical Social Sensing Co-Simulators
## 4 Experimental Validation: Co-Simulator Development and Experiment Description
### Experiment Description
#### 4.2.3 Simulation Scenario  
In order to perform the described experiments, a particular simulation scenario was defined. One of the most interesting topics nowadays is the adequacy of public infrastructures to emergency and evacuation situations (in order to avoid human avalanches, bottlenecks at the exits, etc.). In these situations, communication networks (especially proprietary WiFi networks) support a high stress and,even and depending on the situation, they may get isolated and uncommunicated. Besides, in these situations, people many times behave in a non-standard way, so regular emergency systems (such as alarms, panels, etc.) are not as much effective as desired. In these scenarios, then, the physical world (where the emergency starts and evolves), the cyber world (devices and platforms employed nowadays as main information source) and social environment (people) are totally interconnected. Thus, the purpose of the planned simulations is to test the proposed methodology in the creation of a tool for a realistic CPSS application. The simulation scenario is a representation of first floor in one building at the Technical University of Madrid. In those spaces, we consider a certain amount of people moving around with their smartphones and interacting with the rest of people. The simulation scenario includes three corridors, ten classrooms (some of which were cooled) and other minor spaces (such as a small hall). As maximum, 800 people can be at the same time in that space. Figure 15 represents that scenario. A fire was simulated in that scenario, where and evacuation was, then, started. The differences of temperature in the building and the information provided from the emergencies system forced people to move and interact with the others. These temperature differences cause both the people movement to change and the quality of communications to go down (properties of wireless channel change). At the same time, smartphones registered the social information and transmitted the acquired data to a central server deployed in a computer center near the simulated building (where the actions to be taken in order to manage people were calculated). With this information, groups of people may be located, specific evacuation plans and information may be communicated, etc. The simulation pretended to calculate the system evolution along the first ten minutes. During the first experiment (experiment#1), the expert on crowd simulations performed various simulations modifying as much aspects as he considered adequate to evaluate the proposed quality parameters. During the second experiment (experiment#2) the explained simulation was repeated considering different amounts of people in the building. In that way, it was possible to know if the difference in the development time between the methodological simulator and an identical simulator which implements parallel execution (simulator#3) justifies the use of the stop-and-wait mechanism. Finally, during the third experiment (experiment#3), simulation was repeated considering different values for the variables under study (namely, the number of agents in the scenario, the number of parameters per agent and the temporal step). For every case, simulation was repeated fifteen (15) times and the final result was calculated as the medium value. Figure 15: Simulated space. In order to simulate each one of the proposed sub-systems (social environment, physical world and cyber domain) libraries and state-of-the-art proposal have been employed. In particular, cellular network and WiFi elements have been simulated employing some existing NS3 libraries (WiFi and LTE modules). Social environment has been programmed using the MASON tools and proposals about emergency simulations [136]. The basic idea is to employ the inertial sensors included into intelligent terminals to determine the people behavior during the emergency (if panic is present, people keep calm, etc.).