  Maintaining peer-to-peer connectivity with low energy overhead is a key
requirement for several emerging Internet of Things (IoT) applications. It is
also desirable to develop such connectivity solutions for non-static network
topologies, so that resilience to device failures can be fully realized.
Decentralized clustering has emerged as a promising technique to address this
critical challenge. Clustering of nodes around cluster heads (CHs) provides an
energy-efficient two-tier framework for peer-to-peer communication. At the same
time, decentralization ensures that the framework can quickly adapt to a
dynamically changing network topology. Although some decentralized clustering
solutions have been proposed in the literature, they either lack guarantees on
connectivity or incur significant energy overhead to maintain the clusters. In
this paper, we present Decentralized Connected Resilient IoT Clustering
(DeCoRIC), an energy-efficient clustering scheme that is self-organizing and
resilient to network changes while guaranteeing connectivity. Using experiments
implemented on the Contiki simulator, we show that our clustering scheme adapts
itself to node faults in a time-bound manner. Our experiments show that DeCoRIC
achieves 100% connectivity among all nodes while improving the power efficiency
of nodes in the system compared to the state-of-the-art techniques BEEM and
LEACH by up to 110% and 70%, respectively. The improved power efficiency also
translates to longer lifetime before first node death with a best-case of 109%
longer than BEEM and 42% longer than LEACH.
