Disruption Tolerant Networking
In a challenged environment, the network connectivity and reliability is severely constrained by environment conditions, and is frequently disruptive. For example, a seismic network comprises 50 broadband seismic stations along a 500km line across Mexico from Acapulco to Tampico. Stations were placed roughly every 5 km. In this wide area deployment, the network is vulnerable and disruptive, hence a Disruption
Tolerant Shell (DTS) mechanism is used to handle network breaks and avoid data loss, similar as the data bundle approach in Inter Planetary Network project where the hop delay may be arbitrarily long (e.g., hours even days).
A disruptive network poses significant new research challenges. In traditional network, we typically assume that the network connectivity is relatively stable; at least a neighbor node can be connected when needed (at most after certain delay). A disruptive network fundamentally undermines this assumption. The transient and intermittent network connectivity make traditional routing protocols unsuitable. The traditional routing protocols choose the best sequence of nodes between the source and destination, and forward each packet through that sequence until next routing update period. In a challenged environment, a predictable and stable path may never exist, the network connectivity is intermittent, and a node could suddenly appear or disappear. The link quality may vary significantly and asymmetric links are common.
To deal with a challenged sensor network, it is crucial to capture the opportunistic connectivity for data delivery. We argue that a fundamental rethinking on wireless network model and communication protocols is needed.
