One of the main constraints in wireless sensor networks (WSNs) is the energy consumption. To mitigate this limitation and to prolong network life-time, stability period and throughput, this paper proposes new cluster-heads selection protocols, they based on Stable Election Protocol (SEP) and Distributed Energy-Efficient Clustering (DEEC). We first propose Enhanced Zonal-SEP (EZSEP) and Zonal Threshold-DEEC (ZTDEEC) protocols, the proposed protocols are based on dividing the network field into certain zones, this will improve the connectivity of the far normal nodes with the base station (BS). Several evaluation metrics are used to compare between the proposed protocols and the conventional ZSEP and TDEEC protocols such as: network stability, instability period, life-time and throughput. Considering the same total initial energy, the obtained results show that the proposed EZSEP slightly outperforms the conventional ZSEP in terms of network stability, instability period and life-time, it achieves enormous improvements in terms of throughput as more nodes can transmit direct to BS. On the other hand, the proposed ZTDEEC provides huge improvements in terms of all the evaluation metrics mentioned above. To further improve the network life-time and network throughput, we propose Threshold-based EZSEP (TE-ZSEP) and Enhanced-ZTDEEC (EZ-TDEEC) protocols, in these two new protocols we redefine the threshold formula used in EZSEP and ZTDEEC to consider both weighted energy and weighted distance parameters. By combining the idea of dividing the network field into certain zones and the new threshold formula, the proposed TE-ZSEP and EZ-TDEEC protocols can effectively improve the energy consumption in heterogeneous WSN and prolong its life-time as proved by the obtained results.

The design of an energy-efficient routing protocol is crucial for extending the lifetime of limited energy-constrained wireless sensor networks (WSNs). To achieve this goal, the authors propose three proactive routing protocols; the first protocol is a circle zone stable election protocol (CZSEP). This protocol is a two-level heterogeneous energy protocol with a circle zone located at the centre of the network field and used to deploy the normal nodes and with advanced nodes that are randomly distributed around the circle zone. The performance of the proposed CZSEP was compared to that of the conventional ZSEP considering the same total initial energy. To further improve the performance of CZSEP, they propose the second protocol named as, CZSEP with helper nodes (CZSEP-HN) which is a three-level heterogeneous energy protocol. In CZSEP-HN, they add helper nodes in certain places in the network field to minimise the energy consumption in the considered network. Both CZSEP and CZSEP-HN can overcome the problem of large transmission distance between normal nodes and the base station (BS) and between cluster-heads and BS exists in conventional ZSEP. Finally, they propose the third protocol, which is a modified CZSEP-HN (MCZSEP-HN) to overcome the problem of energy consumption in CZSEP-HN. MCZSEP-HN is a fourlevel heterogeneous energy protocol with two circle zones one for normal nodes and the other for intermediate nodes. The obtained results showed that the MCZSEP-HN outperforms the other protocols in terms of lifetime , throughput, stability and instability period and can reduce the energy consumption in WSNs.

Abstract