## 3 Proposed UGAVs-MDVR Protocol  
The protocols reviewed in the literature show that these protocols cannot be used for MDM dissemination in real time because these are developed for handling the traffic of urban or highway scenarios. Moreover, applying a single VANET protocol in all scenarios is impossible. Besides this, there is a need to propose a better solution for 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.  
Combining UGVs and UAVs into a single routing scheme for message MDM dissemination is required with strong IVC links and an effective central coordination system to reduce any likelihood of delay or failure in MDM dissemination. Moreover, there is also a need for a scheme in which the mine-detection vehicles can move in groups to clear the required piece of land of buried mines. These vehicles share information in a central coordination system led by the head of the cluster and are able to adapt themselves to unpredictable scenarios.  
Hence, our previous work [20; 21; 55] has been enhanced by introducing UAVs to overcome the existing VANET challenges, as discussed earlier. The basic layout and structure of communication between UGVs and UAVs have been implemented only to analyze the scheme's performance [55]. In the current research, the scheme of cluster formation, cluster-head election, and cluster speed-limit features have been enhanced. The cluster members joining the scheme and cluster merging process have been refined and implemented along with the computation of the speed and direction. Moreover, the scheme for cluster-head election and cluster management has also been improved. Hence, the proposed protocol's architecture and performance have been significantly enhanced.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Sr. No**} & \multirow{2}{*}{**Protocols**} & \multirow{2}{*}{**Geographical**} & \multirow{2}{*}{**Cluster-Based**} & \multirow{2}{*}{**Spatiotemporary**} & \multicolumn{2}{c}{\begin{tabular}{c} **Store and** \\ **Forward** \\ **Scheme** \\ \end{tabular} } & \multicolumn{2}{c}{\
\begin{tabular}{c} **UGVs or** \\ **UAVs** \\ **Enable** \\ \end{tabular} } & \multicolumn{2}{c}{
\begin{tabular}{c} **Location-** \\ **Based** \\ \end{tabular} } \\ \hline
1 & COIN [31] & N & Y & N & N & N & Y \\
2 & IVG [33] & Y & N & N & Y & N & Y \\
3 & Cached Geocast [34; 35] & Y & N & N & Y & N & Y \\
4 & Abiding Geocast [34] & Y & N & Y & Y & N & Y \\
5 & GVGVI [36] & Y & N & N & Y & N & Y \\
6 & Modicast [37] & Y & N & Y & N & N & Y \\
7 & DTSG [38] & Y & N & N & N & N & Y \\
8 & CBDRP [32] & N & Y & N & Y & N & Y \\
9 & Constrained Geocast [39] & Y & N & N & Y & N & Y \\
10 & Geocache Protocol [40] & Y & N & N & N & N & Y \\
11 & Dynamic Routing [41] & N & N & N & N & N & Y \\
12 & Path Planning [42] & N & N & N & N & N & Y \\
13 & Relay Selection for UAVs [43] & N & N & N & Y & Y & Y \\
14 & Leveraging Communications & N & N & N & N & Y & Y \\  & UAVs [44] & N & N & N & N & Y & Y \\ \hline \hline \end{tabular}
\end{table}
Table 1: Comparison Summary of Existing Routing Protocols.  
The hierarchical approach of the proposed protocol reduces the network overhead and delay along with the increase in throughput caused by the logical organization of UGVs in clusters [56]. The hierarchical scheme consists of the following stages:  
1. Cluster creation (CC),
2. Level-based cluster-head election (LBCHE),
3. Multicast routing (MRT),
4. Cluster maintenance (CMN)