Fail-Safe Hierarchical Organization for Wireless Sensor Networks

This paper presents the definition and evaluation of a new protocol for providing a wireless sensor network (WSN) with a hierarchical organization. Differently from previously proposed solutions, our protocol, termed CC ("double c," for clique clustering), includes in its operation a fail-safe mechanism for dealing with node failure or removal, which are typical of WSNs. More specifically, the network is partitioned into clusters that are cliques, i.e., nodes in each clusters are directly connected to each others. An efficient mechanism for building a connected backbone among the clique clusters is provided. Clustering, backbone formation and backbone maintenance are completely localized, in the precise sense that only nodes physically close to a failing node are involved in the reconfiguration process. We compare the performance of CC with that of DMAC, a protocol that has been previously proposed for building and maintaining clusters and backbones in presence of node removal. Our comparison concerns metrics that are central to WSN research, such as time for clustering and backbone reorganization, corresponding overhead (in bytes and transmission energy), backbone size, extent of the reorganization (i.e., the number of nodes involved in it), and backbone route length. Our ns2-based simulation results show that the design criteria chosen for CC are effective in producing backbones that can be reconfigured quickly (63% faster than DMAC\´s) and with remarkably lower overhead.