Low Latency Fog Computing Architecture for a Fire Safety Application

Sammanfattning: This thesis presents an architectural design for location-aware fire safety application (Fire-fly) based on cloud and fog computing. The Fire-fly application is designed to assist the residents of a building to be notified and evacuate individually in a fire emergency that is happening in the building by the help of sensor readings collected from within the building. A part of this thesis explains how this application is implemented using different types of communication models and protocols between different clients of the Fire-fly application. The communication latency is then measured and compared between cloud and fog architectures. When it comes to communication between different clients, the fog architecture might be a preferred choice because it has lower latency than the cloud based architecture. However this preference is questioned when it comes to dependability aspect. Therefore, this thesis also studies the dependability trade-off the fog architecture has by studying the availability of the fog architecture in a simulated failure of part of the fog architecture. The system restoration period of the fog architecture is measured by suddenly shutting down parts of the fog structure that are most likely expected to be exposed to physical damages because of fire. The following results are achieved after testing the whole system on a test site: the average time it takes for data that contains location information from the resident client to arrive at the fire brigade client for the cloud infrastructure was 277 ms and for the fog was 14 ms. The results achieved from the service restoration period will approximately take on average 530 ms for a resident client to reconnect to a another functioning fog-cell in case of disconnection due to fire, and it takes on average 940 ms to reconnect to the cloud.