SIGPRO: A Real-Time Progressive Notification System Using MQTT Bridges and Topic Hierarchy for Rapid Location of Missing Persons

Currently, one of the main challenges that the world's big cities are facing is the security problem of their citizens and specifically the disappearance of people (even more in Latin America countries). Thus, to address this problem, a software system called SiGPro has been developed, which allows notifications for the early location of missing persons, using some technological tools, being one of the most prominent application of the MQTT protocol frequently used in the Internet of Things (IoT). SiGPro applies a MQTT-Bridge for hierarchical server communication and developing the software system for real-time performance. SiGPro innovates a Progressive Notification Mechanism, not considered in other similar projects and being one of the main contributions of this research; it delivers notifications depending on the disappearance distance in order to not saturate the end user. In addition, SiGPro was deployed in three cities in Ecuador, (being Quito city the MQTT-broker), where more than 140 users participated in each city and in different test scenarios. Time and distances of disappearance solution were obtained, taking into account the total anonymity of the victim. Finally, SigPro has shown that increasing crowdsensing (number of users), reduces the distance at which the missing person has been located.