## 1 Introduction  
WSNs consist of tiny sensor nodes made for data sensing, data computation, data transmission and data reception tasks. Unlike wired network scenarios, wireless sensor nodes transmit the sequence of environmental data from one location to another location via open multi-hop channels. In this case, each sensor node is intended to broadcast beacon messages to recognized neighbor sensor nodes in order to establish multi-hop channels. At the same time, each sensor node must hear the requests coming from other sensor nodes. Thus, the sensor nodes crucially spend significant amounts of energy in listening states. As the sensor nodes are vulnerable to resource limitations in real-time conditions, wireless network protocols and communication frameworks are expected with energy consideration functions. Generally, WSNs manage various services in their protocol stack, such as mobility management, security management, power management, event management and quality management. The application-specific WSN architectures are deployed in order to provide various levels of network services. Wireless physical layer functions, WMAC functions and wireless routing protocols are the major considerations for achieving superior data transmission in WSNs. In this regard, configured physical layer parameters and nodes' effective attributes initiate network operations. To an extent, wireless channel allotment policies (scheduled or random) are decided by WMAC procedures. Similarly, identifying optimal routes for multi-hop data communication along the channel from source node to destination node must be configured with the help of suitable wireless routing protocols. According to the deployment strategies of WSNs, the routing protocols are chosen to enable a multi-path routing process or a uni-path routing process. Along the execution of layering functions in the network, each sensor node receives irregular energy distribution, computation load and memory utilization. Under the conventional or standard network functions, the lifetime of the WSN is unacceptably undersized. The lifetime of the WSN or sensor nodes can be increased through proper energy utilization policies and load distribution policies. These policies are expected in MAC and route management tasks. Initiating crucial experimental analysis over various WSN-based energy optimization techniques and load optimization techniques provides a new motivation for future research works. In this concern, the individual energy optimization rules established for WMAC and routing function in each node ensure the entire network's lifetime and link availability. The importance of energy-sensitive communication protocols is seriously considered for research under WMAC and routing layer functions. As WMAC and routing jobs are more closely related to channel liveliness than other layers, the need for controlling energy wastage along the respective channel is a critical task. In the same manner, multi-path routing protocols are noted as better solutions than uni-path routing mechanisms against security threats. Apart from physical architectures, the sensor nodes require logical neighbor association rules to build usable network channels. Logical network configuration and successful data communication are confirmed through effective WMAC principles and resilient routing protocols, respectively. On the other hand, energy-efficient WMAC procedures and routing protocols are widely expected in each wireless sensor node to save the individual node's energy. With this in mind, this experimental survey has been initiated from the study of the WSN's characteristics, types, future-generation policies and real-time network problems. Accordingly, the major problems and solutions are described, as given in Table 1.  
As given in Table 1, the general aspects and WSN characteristics are discussed. In addition, other research works [17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27] discuss various resource allocation issues, routing protocols, smart sensor characteristics and energy problems of WSNs.