Opportunistic databank: A context aware on-the-fly data center for mobile networks

In recent years, significant advancement in the wireless communication technologies, such as Bluetooth, 802.11/WiFi, and ZigBee, has been seen in mobile ad hoc networks (MANETs). Such technologies enable mobile devices to form on-the-fly data centers where nodes opportunistically participate in data storage and sharing applications. In such a setup, the basic assumption is that there must exist an end-to-end communication path between a source and a destination node. Every mobile host acts as a router and communicates with other mobile hosts. Even if source and destination mobile hosts are not in each other’s communication range, data is still forwarded to the destination mobile host by relaying transmission through other mobile hosts that exist between the source and the destination nodes. The scenarios when there are frequent disruptions and delays in message transfer due to network partitioning, higher degree of variation in network topology, and sparsity of nodes, such network environments are known as Delay Tolerant Networks (DTNs). The DTNs lack end-to-end communication paths between source and destination nodes. Numerous DTN scenarios that correspond to opportunistic data storage/sharing applications include: (a) disaster/emergency response systems, (b) battlefield networks, (c) sensor networks, (d) road traffic information dissemination systems, (e) content dissemination systems, and (f) cellular traffic data offloading. In the aforementioned scenarios, the cellular 3G infrastructure may usually be unavailable, or if available, provide too limited bandwidth to transmit data traffic. Instead, mobile users rely on their opportunistic contacts for storing, sharing, and accessing data.