Cluster-centric medium access control for WSNs in structural health monitoring

Wireless sensor networks (WSNs) are designed for sensing phenomenon and acquiring data. In structural health monitoring (SHM) of critical infrastructure, increasingly large number of sensor nodes are deployed to acquire data at the spatial density needed for structural integrity assessment. After rare catastrophic events such as earthquakes, a large volume of data related to the event can be produced in an instant and need to be sent (to remote locations) for analysis. When many nodes are trying to transmit their data simultaneously, the contention for the wireless channel increases the probability of packet collisions resulting in packet drops, multiple retransmission attempts and consequently delays; it is also not uncommon to find certain nodes (e.g. closer to the sink) having better chances of successful transmission leading to biased data delivery. While clustering has been extensively used to reduce contention in wireless networks, researchers have not given adequate attention to cluster-level performance, preferring to focus on node-level performance. This paper presents a new perspective on cluster-based WSNs and proposes a cluster centric design that aims to tackle medium access control (MAC) layer congestion associated with burst packet generation in an unbiased manner, making it suitable for applications like SHM.