Obtaining Robust Wireless Sensor Networks through Self-Organization of Heterogeneous Connectivity

A Wireless Sensor Network (WSN) is a set of sensor nodes that can communicate wirelessly with each other across an extended environment. Sensor networks are being used for various military, environmental, human-centric and robotic applications [Arampatzis 2005]. Most of the research on WSNs is focused on networks with identical nodes that have the same transmission range. This creates a homogeneous network whose connectivity can be modeled as an undirected graph. Homogenous networks are simple to analyze, but are well-known to be suboptimal with regard to efficiency, longevity and robustness [Yarvis 2005]. The random deployment of homogeneous nodes results in an uneven connectivity with critical nodes, making the network non-robust to node failure. A simple solution to overcome this problem would be to increase the transmission range of all nodes, but, this creates undue congestion in other parts of the network. In a heterogeneous network, in contrast, nodes can individually select their transmission range and tune their connectivity locally without creating congestion. This effectively reduces the number of hops between nodes without increasing bandwidth needs and energy. Though the resulting networks are more efficient and robust than homogeneous ones, they are difficult to analyze (see Duarte-Melo et al. [Duarte-Melo 2002] for some analysis).