When stricken by a catastrophic natural disaster, the efficiency of disaster response operation is very critical to life saving. The efficiency of disaster response operation is greatly depending on communication systems. However, they were usually not dependable, including cellular networks, and often crashed due to power outage and backhaul link breakage. The failure of communication systems caused a big coordination problem to many disaster response operations. This thesis proposes a Contingency Cellular Network (CCN) by connecting isolated base stations to survival base stations using long-range wireless links to recover part of cellular network functionality. People can use their own cell phones for emergency communication in the disaster areas. CCN will be able to support a large number of disaster responders with limited resources in the early hours of disasters, thus to save many lives.
Because the reliability of database plays a very important role in the CCN, this thesis proposes a distributed database architecture to improve the reliability of database so as the reliability of CCN. We take advantage of the simplicity of CCN tree topology to design three distributed database architectures: (1) Hierarchical Redundancy Architecture for “Group_Member ” table, (2) Hierarchical Redundancy Architecture for “HLR” table, and (3) Hierarchical Neighboring Redundancy Architecture for “HLR” table. The tree topology greatly simplified the query and update procedures. We use availability and average total cost to analytically evaluate all three architectures trying to identify the most appropriate architecture under different circumstances. Based on our evaluation results, CCN operators can choose the most appropriate architecture according to their realistic circumstances.
Finally, in order to verify the feasibility of the proposed architectures, we implemented a simplified prototype using several laptops and Android mobile phones. The Hierarchical Redundancy Architecture and the Neighboring Redundancy Architecture were implemented. The results show that both architectures can be functional with reasonable performance except that Hierarchical Neighboring Redundancy Architecture may take longer time, but in a tolerable range, to setup a call