**9. Design of WSN-Specific CA-IoT Routing Protocol**

This section proposes a CA-IoT-based supervisory routing protocol that supports static SNs, rotatable/fixed CH roles, and enhanced SN resource management under the deterministic deployment approach. This can improve energy savings, connectivity, distance moderation, and multihop inter-cluster communication in the resulting network. The operational cycle and the embedded activities of our WSN-based CA-IoT protocol for precision irrigation application, as illustrated in Figure 21, include the following:


**Figure 21.** Proposed operation cycle for designing our CA-IoT network's routing protocol.

Additionally, Figure 21 uniquely incorporates correlated pairing-based duty cycling, constant control message complexity FM/data redundancy scheme, network construction/maintenance, and cluster quality measures that can ensure unprecedented energy savings and event data quality. This clustering approach can further minimize energy wastage via a suitable MAC method, a low-power wireless communication standard, data aggregation with data redundancy checks, and CH role rotation, among other factors. Although the various sections of the deduced MOO metrics have been implemented in our CA-IoT operational cycle, the most desired performance can be optimally attained when the MOO metrics are modeled into their respective objective functions, and their optimal values are determined and implemented in both simulation and testbed experiments in future works. Also, a realistic multihop routing framework can also be inculcated into this protocol for large-scale applications.

#### **10. Open Issues and Future Works: Cluster-Based WSN-Specific Agri-IoT Networks**

This tutorial has firmly established that the WSN-based Agri-IoT is an indispensable component of smart or precision farming and greenhouses, despite its resource- and deployment-induced challenges [12,26,141]. Unlike the conventional IoT, Agri-IoT is compelled to drive on batteries and affordable task-scalable SNs. However, it must meet the expectations in Figure 2 to guarantee a stable performance. The cluster-based routing technique has emerged with promising potential to mitigate these challenges. However, results from existing testbed solutions in this study show otherwise due to the absence of a contextualized in-depth overview of Agri-IoT as well as the following open issues which have not received extensive contextual research considerations in Agri-IoT applications:


anisms and the capacity to detect and self-heal root faults (SN-out-of-service and sensory data outliers [25]), not their effects.


#### **11. Conclusion and Future Works**

This tutorial presented: (1) a systematic overview of the fundamental concepts, technologies, and architectural standards of WSN-based Agri-IoT; (2) an evaluation of the technical design requirements of a robust, ubiquitous, self-healing, energy-efficient, adaptive, and affordable Agri-IoT; (3) a comprehensive survey of the benchmarking FM techniques, communication standards, routing protocols, MMAC protocols, and WSN-based testbed solutions; and (4) an in-depth case study on how to design a self-healing, energy-efficient, affordable, adaptive, stable, and cluster-based WSN-specific Agri-IoT from a proposed taxonomy of MOO metrics that can guarantee optimized network performance. Furthermore, this tutorial established new taxonomies of faults, architectural layers, and MOO metrics for CA-IoT networks. Using the open technical issues, it recommended applicationspecific requirements of Agri-IoT, general design expectations, and remedial measures, and it evaluated them in CA-IoT for precision irrigation in order to optimally exploit the proposed MOO metrics in a typical CA-IoT design in both simulation and real-world deployment scenarios. Overall, this tutorial can serve as a new reference document for the IoT community and Agri-IoT designers, since it adequately examined all critical aspects of WSN-based Agri-IoT networks from theoretical modeling to real-world implementation.

**Author Contributions:** The First Author contributed 60% while the second the third Authors contributed 20% each. Conceptualization, E.E.; methodology, A.M.W.; writing, review and editing, E.E., O.T. and A.M.W.; supervision, O.T. and A.M.W.; project administration, E.E.; and funding acquisition, E.E., and O.T. All authors have read and agreed to the published version of the manuscript.

**Funding:** The work was carried out with the financial support of icipe- World Bank Financing Agreement No D347-3A and the World Bank Korea Trust Fund Agreement No TF0A8639 for the PASET Regional Scholarship and Innovation Fund. The views expressed herein do not necessarily reflect the official opinions of the donors.

**Data Availability Statement:** This research has no such data.

**Conflicts of Interest:** The authors declare no conflict of interest.
