Decentralized Communication Services for Post-Disaster Scenarios, Resource Allocation, Prioritization, and Long-Range Communication Support

Our modern society strongly depends on critical infrastructures, such as the central power grid or information and communication technology. When these infrastructures fail during and after disasters, the affected population has no means of communication. At the same time, the increased population density of urban areas coupled with the peoples’ expectation to have permanent access to communication systems and to be informed at all times and at any place, has made disaster-management increasingly challenging. Communication is crucial during disasters as it empowers the affected population to organize and help themselves. But even if parts of the communication infrastructure are still intact, the increased communication demand for disaster relief efforts and checking on loved ones typically overloads the available infrastructure. As such, infrastructure-independent and rapidly deployable communication systems are required. Delay-tolerant ad-hoc networks can be used to build communication networks, which propagate messages via the store-carry-forward paradigm directly between neighboring communication devices. Such DTN-MANETs can be formed by the smartphones of the affected population. However, such communication networks must overcome various scenario-specific difficulties, such as limited network lifetime due to limited battery power of the devices, message propagation limitations caused by isolated network areas due to the limited range of device-to-device communication, and network resource restrictions. In this thesis, we first assess scenario-specific characteristics by conducting and evaluating a large-scale field test. Based on these results, our main contribution is the design and implementation of the decentralized disaster communication system D2CS.KOM, which extends the functionality of conventional DTN-MANETs. We enable D2CS.KOM to allocate available energy resources to the network participants in a fully decentralized way, extending the lifetime of communication devices and thus the overall network. We further propose and integrate a prioritization architecture to improve the propagation of disaster-relevant messages in the network and enable the system to adapt to continuously changing communication demands. Since the mobility of network participants determines the performance of data dissemination in DTN-MANETs, D2CS.KOM overcomes this limitation by utilizing Unmanned Aerial Vehicles (UAVs) to strategically support the dissemination of messages. We generalize disaster-specific characteristics into the Simonstrator.KOM simulation platform and conduct an extensive evaluation of our contributions. We show that our system extends the communication lifetime of individual nodes and consequently of the overall network while prioritizing disaster-relevant messages. Additionally, we demonstrate the significant support capabilities of UAVs in intermittent DTN-MANETs. In summary, we show that our contributions constitute a significant step towards ensuring communication during and after disasters by improving upon decentralized, infrastructure-independent communication systems