Quality of Service and Capacity in Constrained Intermittent-Connectivity Networks

In an intermittent-connectivity network, there rarely exists a connected path between a source node and its destination. These networks arise frequently when each node has a limited transmission range, such as a communication network between separated villages or a surveillance network with a large geographical span. One method of addressing the low connectivity of the network uses redundancy. A node generates and stores data; upon reaching the communication range of another node, it replicates the data to it. Multiple copies of the packet decrease the time to offload the data to the destination, but increase the energy and storage used in the system. In this paper, we quantify the resource-delay trade-off and the throughput capacity for intermittent-connectivity networks with Quality of Service restrictions such as limited communication bandwidth. Many routing protocols have been proposed for these intermittent-connectivity networks. Using the Shared Wireless Infostation Model as an example strategy, we mathematically represent the intermittent-connectivity network and adjust the model to include a Quality of Service constraint. By completely defining a mathematical model, we allow network designers control over system performance through the adjustment of allocated resources such as communication bandwidth, fraction of time a node spends in sleep mode, or required reliability of packet offloading.