Clustering-based heterogeneous optimized-HEED protocols for WSNs

Clustering-based networks play a vital role in efficient utilization of energy consumption of each sensor node (SN) in wireless sensor networks (WSNs). Furthermore, firstly, prolonged network's lifetime is observed as the key factor to analyze the protocol's efficiency. However, in critical applications, i.e., military surveillance, environmental monitoring and structural health monitoring, stability region is also an important aspect for consideration. This provides reliability of data from each SN in the network. On the other hand, once a SN dies at any region, we are not able to sense that region which leaves the region vulnerable from detection of events. With this reason, it is highly important for an energy efficient protocol to provide good stability region with prolonged network lifetime. Secondly, a protocol should be intelligent enough to handle homogeneous as well as heterogeneous nodes efficiently in the network (i.e., homogeneous and heterogeneous WSNs) because once the network executes, a homogeneous WSN is also transformed in heterogeneous WSN. This is because of different radio communication features, occurrence of random events or morphological attributes of the network field. optimized-HEED protocols are one of the most recent clustering-based algorithms which improved the various shortcomings of classical protocol, i.e., HEED and provided far efficient results in terms of energy consumption, load balancing and network lifetime. However, these demonstrated their efficiency for homogeneous WSN only. In this paper, we extend the optimized-HEED protocols for heterogeneous WSNs model on the basis of varying levels of node heterogeneity (in terms of energy), i.e., 1-level, 2-level, 3-level and multi-level, and propose these as heterogeneous optimized-HEED (Hetero-OHEED) protocols. Simulation results confirm that by increasing the level of node's heterogeneity, stability region of each Hetero-OHEED protocol enhances extremely with prolonged network lifetime. These provide a rich solution in designing of efficient protocols for those applications, where stability region and network lifetime require equal importance.