A Sensor-Assisted Emergency Guiding System: Sensor-Centric or User-Centric?

The goal of sensor-assisted emergency guiding systems is to guide people to exits as soon as possible in emergencies (e.g., fires in buildings). Sensors are deployed in a smart environment to monitor and detect hazards. Sensors collaborate with each other to compute guiding paths for people in case of emergencies. To achieve this goal, this paper focuses on the sensor-assisted guiding problem, which studies how to guide people to exits quickly. Thus, the sensor-assisted guiding problem is analyzed from two different aspects: the sensor-centric guiding problem and the user-centric guiding problem. The former is to find a guiding direction for each single sensor for evacuating people nearby, whereas the latter is to find a personalized guiding direction for each individual user. In other words, the number of guiding directions provided by each single sensor in the sensor-centric guiding problem is limited, whereas this constraint is relaxed in the user-centric guiding problem. This paper proves that the sensor-centric guiding problem is NP-hard. When the constraint is relaxed, a user-centric guiding system is more efficient. Then, this paper designs a localized user-centric guiding protocol, which allows each sensor to provide more than one guiding direction for personalized guiding. The key idea of the proposed protocol is to estimate the evacuation time in a distributed manner. Extensive simulation results show that the proposed solution can significantly reduce the evacuation time by 15% compared to typical sensor-centric approaches. Finally, the implemented prototype indicates that proposed protocol is lightweight and can work with real sensor platforms.