## 2 Materials and Methods
### Technical Discussions on Related Works
#### 2.1.3 Energy-Efficient Wireless Routing Strategies and Protocols  
The significance of integrated WMAC principles and wireless routing protocols are identified around the research community arena. Most of the research works focused on the energy-saving plans of WSNs having determinations with WMAC policies only. However, route discovery, route management and data routing protocols heavily control the energy release rate in each sensor node. As a result, the inventions on individual energy-efficient WMAC protocols, energy-efficient routing protocols and hybrid interface energy management principles are inescapably required. [PERSON] et al. [52] described various wireless routing solutions such as cluster-based routing protocols, hierarchical routing protocols, random (flat) routing protocols, node-centric routing protocols, data-centric routing protocols, static routing protocols, mobility-support routing protocols, time-sensitive routing protocols and other geography-aware routing protocols. In addition to these protocols, wireless networks and WSNs focus on application-specific routing protocols, medium-specific routing protocols and energy-efficient routing protocols. Each routing protocol has many variances, such as low-energy adaptive clustered hierarchy (LEACH), dynamic source routing (DSR), ad hoc on-demand distance vector routing (AODV), temporary ordered routing algorithm (TORA), the real-time routing protocol (RTRP), geographic and location-based routing protocol (GLRP), QoS-based routing protocol (QRP) and other protocols. Among these protocols, the strategy of data communication and route management policies are initiated in a proactive manner or reactive manner. Figure 2 relates the energy-efficient rules required at each layer. As illustrated in Figure 2, the top-down communication (network layer to MAC layer) and upward communication (MAC layer to network layer) are expected to attain the energy controlling principles to increase the lifetime of WSNs. The routing protocols used for WSNs are anticipated to perform successful data communication with optimal energy-saving rules compared to other types of wireless networks. Since the internal resources of sensor nodes are more limited than other network nodes, the effective governance of suitable energy-saving mechanisms are highly needed at routing layer functions. The requirements of future-generation networks, IoT systems, are progressively specified by different researchers. In this manner, [PERSON] et al. [53] identified the importance of energy-efficient future-generation networks and fifth-generation IoT systems and wireless technologies. The reliability, scalability and lifespan of future-generation IoT systems are sorely needed to manage multiple-input and multiple-output channels. This work mainly focuses on the development of fifth-generation routing principles with energy optimization techniques to handle multi-channel data transmission practices. Notably, the distributed load balancing mechanisms, energy sharing principle and heterogeneous channel allocations are considered major technical problems in this domain. In another way, the assumptions of this proposed model lead to clustered IoT-based WSNs. Similarly, the prospects of flat IoT models, coverage liability and appropriate energy-saving routing models cannot be ignored around the domain of wireless technologies [54; 55]. [PERSON] et al. [56] proposed an optimized zonal energy-balancing technique and adaptive [PERSON]'s technique for improving routing principles. This method evaluates the node's transmission distance and residual energy in the network. In this manner, the entire wireless network (personal network) has been divided into various local zones to ensure the even distribution of the communication load. At the same time, optimized shortest-path routing algorithms are applied to manage the energy consumptions of each sensor node in a balanced manner. This scheme justifies that the proposed technique has a confirmed packet transmission ratio, energy wastage and routing delay.