Wireless sensor networks: to cluster or not to cluster?

The key challenge in the design and operation of wireless sensor networks (WSNs) is the maximization of system lifetime. Node clustering is commonly considered as one of the most promising techniques for dealing with the given challenge, and as such has been referred to by many researchers. It is interesting to observe, however, that very few, if any, published research works provide explicit analysis of node clustering in WSNs and/or manage to prove its actual effectiveness. In this paper we take a closer analytical look at WSNs of clustered organization. We prove that these networks do not necessarily outperform non-clustered WSNs. The condition that ensures superior performance of clustered WSNs, with absolute certainty, is that the formed clusters lie within the isoclusters of the monitored phenomenon. We also show that in clustered WSNs which satisfy the given condition, cluster sizes do not need to match the sizes of their respective underlying isoclusters. Instead, simple 5-hop clusters can provide near-optimal network performance under a wide range of cluster-to-sink and cluster-to-isocluster spatial arrangements