Robust communications for sensor networks in hostile environments

Clustering sensor nodes increases the scalability and energy efficiency of communications among them. In hostile environments, unexpected failures or attacks on cluster heads (through which communication takes place) may partition the network or degrade application performance. In this work, we propose a new approach, REED (Robust Energy Efficient Distributed clustering), for clustering sensors deployed in hostile environments. Our primary objective is to construct a k (i.e., k-connected) network, where k is a constant determined by the application. Fault tolerance can be achieved by selecting k independent sets of cluster heads (i.e., cluster head overlays) on top of the physical network, so that each node can quickly switch to other cluster heads in case of failures or attacks on its current cluster head. The independent cluster head overlays also provide multiple vertex-disjoint routing paths for load balancing and security. Network lifetime is prolonged by selecting cluster heads with high residual energy and low communication cost, and periodically reclustering the network in order to distribute energy consumption among sensor nodes. We prove that REED can asymptotically achieve k tolerance if certain constraints on node density are satisfied. We also investigate via simulations the clustering properties of REED, and show that building multiple cluster head overlays does not consume significant energy.