## 6 Conclusions and Future Perspective  
Routing techniques differ depending on the applications and dependability of the node's hazardous condition. The robustness of the routing strategy is dependent on the network architecture and design of the WSN. The design challenges for routing protocols in WSNs are outlined. Numerous clustering strategies are highlighted, which are projected with comprehensive routing techniques, resulting in improved performance. Fully demonstrated and tested LEACH extends network longevity while eliminating intra-cluster collisions. Researchers have mostly focused on enhancing the CH selection criteria, which have been demonstrated to save energy more efficiently. Owing to the challenges such as power, network scalability, security, and packet-delivery ratio, the LEACH protocol has been modified by researchers over time. This paper intends to present a more comprehensive survey of LEACH-based classical and bio-inspired protocols that will help researchers understand routing protocols with diverse architectures, novel strategies, and enhanced performance. It can be concluded that the LEACH-MAC protocol can be used in networks where life is a major issue. I-LEACH protocol can be beneficial in large scale as well as small networks. Similarly, the LEACH-KH protocol yields a high PDR and can be adopted in networks where reliability is the prime factor.  
There are still research possibilities in real-time applications that solve difficulties with video and image sensors. Because stationary sensor nodes cannot match demand, the network must include node mobility. The primary issue is that the frequent updating locations of the sensor nodes and BS's position deplete the network energy. As a result, the overhead of mobility and topological fluctuations necessitates the invention of unique protocols. Additionally, the wireless connection technology used in a WSN commonly facilitates various types of cyber-attacks when transferring data packets and the randomly moving sensors provide hackers with several opportunities to launch denial of service attacks, thus decreasing the WSN's security. Despite significant research efforts and advances in recent years, there are still many unanswered research concerns with routing in WSNs that need to be addressed. The development of cryptographic methods for authenticated encryption in WSNs that enable privacy and network security can be explored.  
Conceptualization, T.M.B., S.K.M. and U.C.S.; methodology, T.M.B. and B.A.; software, T.M.B. and S.K.M., validation, B.A. and M.S.K.; investigation, T.M.B. and U.C.S.; resources, T.M.B.; data curation, T.M.B.; writing--original draft preparation, T.M.B. and B.A.; supervision, N.B.; project administration, B.A.; formal analysis: N.B.; funding acquisition: N.B. and P.T.; visualization: N.B. and P.T.; writing--review and editing: N.B. and P.T.; figures and tables: M.S.K. All authors have read and agreed to the published version of the manuscript.  
This work was supported in part by the Framework Agreement between University of Pitesti (Romania) and King Mongkut's University of Technology North Bangkok (Thailand), in part by an International Research Partnership \"Electrical Engineering--Thai French Research Center (EE-TFRC)\" under the project framework of the Lorraine Universite d'Excellence (LUE) in cooperation between Universite de Lorraine and King Mongkut's University of Technology North Bangkok, and in part by the National Research Council of Thailand (NRCT) under Senior Research Scholar Program under Grant No. N42A640328.  
Not applicable.  
The authors declare no conflict of interest.