## 1 Introduction  
UGVs and UAVs have an important role in the recent developments in various fields such as rescue operations, monitoring of inaccessible areas, inspection of building construction, monitoring of electrical work, development of intelligent transportation systems, etc. [1, 2]. UGVs are being used for detecting buried mines to safeguard the civilian population and military troops [3, 4, 5]. According to World Bank and United Nations statistics, hundreds of civilian and military casualties are reported yearly [6]. UGVs are now becoming an essential part of military fleets to meet the challenges of human safety. The efficiency of UGVs can be improved by developing a centralized coordination system based on cluster formation for disseminating the MDMs to incoming vehicles (IVs) successfully, as shown in Figure 1[7, 8, 9]. In this centralized coordinating system, the vehicles share information with the cluster head for making collective decisions within a cluster rather than individual assessments [10]. For example, the movement decisions taken collectively within dangerous remote areas provide safety to mine detection and clearance staff [11; 12]. Inter-vehicular communication (IVC) has been successfully implemented within VANET, where messages are transmitted to incoming vehicles (IVs) about the risks ahead [13; 14; 15]. In VANET, the vehicles communicate with each other at 5.9 GHz within the range of 300-1000 m using the IEEE-802.11p standard [16; 17; 18]. The safety messages and MDM-disseminating schemes have been developed by [PERSON] et al. [19; 20; 21]. However, the defense system analysis (DSA) shows that further work and developments are needed to meet human safety challenges [22]. Therefore, the performance of these protocols is improved by modifying the routing strategy through a combination of UGVs and UAVs. UAVs can maintain a constant altitude of 300 to 1000 m by satisfying the IEEE-802.11p standard range of communication within VANET. Moreover, communication between UGVs and UAVs was also proposed and implemented efficiently for urban areas in [23; 24; 25]. The UAVs can efficiently communicate and disseminate messages from air to air and air to ground, as illustrated in [26; 27]. Combining UGVs and UAVs into a single routing scheme results in strong IVC links and an effective central coordination system, which reduces any likelihood of delay or failure in MDM dissemination. Moreover, the proposed scheme can better address the VANET challenges of network fragmentation, dynamic mobility, delay, unstable IVC links, and overhead by reducing the transmission and communication gap of UGVs by using the air-to-ground links of UAVs. The overhead shows the ratio of total control packets sent to total received data packets at the destination, calculated during dynamic vehicular mobility and by varying the size of the cluster. In the proposed design, the cluster-based scheme is adopted because the nine-detection vehicles need to move in groups to clear the required piece of land of buried mines. Additionally, the UGVs can cooperate better when moving within a single cluster by developing a central coordination system led by the head of the cluster. Furthermore, the overhead is distributed upon several clusters, reducing the delay and increasing the  
Figure 1: Mine detection and message dissemination to incoming UGVs. throughput. Besides this, the UGVs can adapt to unpredictable scenarios such as hilly areas, deserts, rough terrains, irregular trajectories, etc. Equally, the multicast approach enhances the proposed protocol performance manifold by increasing the throughput and reducing the overhead by disseminating the message to desired vehicles only, rather than to all incoming vehicles (IVs) [16,28]. Moreover, the multicasting technique increases the packet delivery ratio [29,30]. The distinctiveness of the proposed protocol can also be found in the several real-time applications in which efficient message dissemination is required, such as during landslides, floods, snow falling, fog, etc.