Secondary cluster head based SEP in heterogeneous WSNs for IoT applications

A wireless sensor network (WSN) consists of specialized sensor nodes that perform sensing services for Internet of Things devices with limited battery power. As the replacement or recharging of batteries is not possible, energy consumption becomes the most important design issue in WSNs. The energy-efficient routing protocol gets the most priority in such energy-constrained networks. The utilization of clustering-based routing protocols like stable election protocol (SEP) has gained much attention as the network's lifetime is significantly improved due to the clustering of sensor nodes. Moreover, the inclusion of a secondary CH (SCH) is beneficial when the member node with the most remaining energy performs data aggregation and reduces the energy burden of the CH. This article characterizes SEP and Prolong SEP (P-SEP) protocols and then extends them by incorporating SCH, which ensures balanced energy consumption. The performance of the proposed Extended SEP and Extended P-SEP protocols has been analysed regarding stability period, network lifetime, energy usage and throughput. The simulation results demonstrate that the proposed protocols outperform state-of-the-art protocols like P-SEP, Modified SEP (M-SEP) and SEP. In particular, the stability period of Extended SEP and Extended P-SEP has improved up to 42% and 89%, respectively, compared to M-SEP.