These concerns can be alleviated by implementing various technology upgrades in traditional WSN methods and schemes. The potential applications of WSN-based IoT required data to be sent to the user with a minimum delay to provide an immediate response to an event, as in the case of tracking. The query response time in a WSN is another key factor in applications such as forest fire detection. Mobile forest fire patrol units can inject queries into the WSN to monitor environmental variables such as temperature and humidity. The WSN must respond to the inquiries as soon as feasible in order to speed up response to a fire and enhance fire prevention efforts [21]. The monitoring applications require successful data reception by the server irrespective of the transmission time. WSNs were first used for military and defense applications, which further motivated researchers to explore new technologies that could enhance their performance [22]. The main domains of applications of the WSNs are as follows:  
1. Environment monitoring: Since the attention on sustainable energy solutions has increased substantially, smart technologies for energy conservation have gained importance. Monitoring environmental conditions have been one of the popular applications of WSN that controls and manages services such as air, water, and soil monitoring [23; 24]. This network allows the end-user to gather data at a resolution located in areas where accessing data is otherwise difficult. Moreover, long-term monitoring is required to obtain sufficient information to decide. 2. Home Application: With the expansion of WSN integrated IoT, tiny sensor nodes can be implanted into household equipment such as electric appliances and furniture to access from a remote place [25]. For instance, the nodes can be incorporated into microwave ovens, vacuum cleaners, washing machines, and even air conditioners that can be connected to a room server. Such arrangements are self-manageable and require minimal human interventions to frame a smart home structure. 3. Healthcare Application: Driven by the convergence of data collection regarding the health of people and maintaining accuracy in collected information with minimal cost, WSN for healthcare has evolved in recent years [26]. Researchers have invented a new branch of WSN exclusive for healthcare, called Body Area Network (BAN), that provides better treatment at a lesser cost. BAN is administered to monitor patients' physiological, cognitive, and psychological information. Figure 2: (a) ADV message. (b) REQ message. * Tracking and Military Application: Battlefield surveillance was a wireless medium's most critical application of sensor networks. Characteristics such as self-association, fast organization, and well adaptation to node failures make WSN an extremely desired sensing technique for military applications [27]. Sensor nodes could be located in remote areas to sense and receive data as long as possible that can alert the user about possible blast location, enemy positions, and chemical attacks. * Transportation: WSN helps drivers alert any congestion or traffic problem by regularly monitoring traffic statistics. Vehicular motions can be tracked instantaneously to avoid any blockage or accidents [28]. WSN also reduces the length of the wiring harness and saves time with the cost of its installation. * Industrial Applications: WSNs offer momentous cost reductions and investments that allow innovative functionalities for industry-based technologies. Continuous sensing of the environment, condition monitoring, and process automation are some of the requirements of Industrial WSN [29]. The solutions need to be simple to use and install yet versatile with low-cost devices and a long lifetime.