## 1 Introduction  
Monitoring is an essential requirement in many applications, such as agriculture [1], healthcare [2; 3], water surveillance systems [4], parking [5], traffic [6], tracking [7], and police and military [8; 9; 10], and is increasing day by day due to the handling of multiple tasks by a single person, whether on-site or remotely. In surveillance systems, numerous high-tech devices, such as digital still and video cameras (CCTVs), charge-coupled devices (CCDs), active-pixel sensors (complementary metal-oxide semiconductor (CMOS) sensors) [11], GPSs, electronic toll takers, tapping devices, walking gait, biometrics, and drones, are used. Therefore, the deployment and maintenance of these systems are very costly and also require skilled people. Some places that are out of reach or are inaccessible require devices that are disposable. These miniaturized, low-cost devices are known as wireless sensor nodes, and multiple such devices form a wireless sensor network (WSN) [12]. These wireless sensor nodes work as the internet of things (IoT) when connected directly to the internet for transferring data without a gateway. The Fourth Industrial Revolution Industry 4.0, smart agriculture, and smart cities are enabled by attaching these sensor nodes and IoT to machines to control remotely [13], as shown in Figure 1.  
The future of connectivity is mostly wireless through the internet and sensor nodes that move, whether they are attached to some vehicle or in the form of unmanned aerial vehicles (UAVs). In mobile surveillance systems, the network scenario has changed from fixed nodes to mobile, meaning the network has a dynamic topology [14]. Some of the applications require the source nodes to be mobile, and in some, the gateway moves, as can be seen in Figure 1 for smart farming and Industry 4.0. As a result, the routing of data packets from the source node to the destination over multiple hops consumes a lot of power due to the re-establishment of routes [15]. Mobile sensor nodes that are battery-powered cannot afford fast battery depletion, which becomes a huge concern, especially in the case of disposable flying sensor nodes [16]. The efficiency of the routing protocol depends on the energy efficiency, multipath, QoS, scalability, location awareness, query, load balancing, fault tolerance, and data aggregation [17]. However, according to the application requirements, the routing protocol properties and type change [14]. In a network, when mobility is enabled, these mobile nodes affect the reliability of data transmission [18; 19]. Many routing protocols address delay issues to enhance data availability [20]. Networks with a dynamic topology, where devices connect and disconnect rapidly, require a cost optimization mechanism that enables and disables features according to the data flow and device capability [21; 22]. In [23], a sustainable routing protocol is introduced to provide flying sensor networks (FSNs) with better connectivity by complex free space propagation on the node to perform area detection. The nodes used in FSNs are low-cost and miniaturized with a slow processor, low memory, and small battery and are unable to handle complex algorithms in real-world scenarios [24]. The cluster-based routing protocol works well in static WSNs or IoT networks [25; 26; 27; 28] but is unable to efficiently route data in an FSN because the node leaves and joins the network rapidly [29]. In [30], a cluster-based routing protocol for an FSN is presented that is based on the predefined static location of the sensor nodes and that of the cluster head. In terms of the mobile node, it remains in a specific area, making its movement strict. Many routing protocols to  
Figure 1: Smart Future. enhance the quality of secure data routing for WSNs with fixed nodes are based on simple nature-inspired optimization algorithms, such as in [31; 32; 33], which cannot handle mobility. Still, resource- or host-based routing support, privacy preservation, and ubiquitous support with simple AI techniques are required for future FSNs [34].