###### Abstract  
Opportunistic Networks (OppNets) are characterized by intermittently connected nodes with fluctuating performance. Their dynamic topology, caused by node movement, activation, and deactivation, often relies on controlled flooding for routing, leading to significant resource consumption and network congestion. To address this challenge, we propose the Adaptive Clustering-based Routing Protocol (ACRP). This ACRP protocol uses the common member-based adaptive dynamic clustering approach to produce optimal clusters, and the OppNet is converted into a TCP/IP network. This protocol adaptively creates dynamic clusters in order to facilitate the routing by converting the network from a disjointed to a connected network. This strategy creates a persistent connection between nodes, resulting in more effective routing and enhanced network performance. It should be noted that ACRP is scalable and applicable to a variety of applications and scenarios, including smart cities, disaster management, military networks, and distant places with inadequate infrastructure. Simulation findings demonstrate that the ACRP protocol outperforms alternative clustering approaches such as kRop, Qo-OLSR, LBC, and CBVRP. The analysis of the ACRP approach reveals that it can boost packet delivery by 28% and improve average end-to-end, throughput, hop count, and reachability metrics by 42%, 45%, 44%, and 80%, respectively. clustering; OppNet (Opportunistic Network); routing protocols; adaptive clustering; heuristic function +
Footnote †: journal: Information  
zones, or space missions. Data transmission in DTNs is opportunistic, utilizing store-and-forward techniques where nodes store messages and forward them to other nodes when direct communication is not possible. DTNs offer a solution to the challenges mentioned earlier for VANETs by being specifically designed to manage prolonged and unpredictable delays in delivering messages. Within DTNs, messages are relayed through intermediary nodes in a step-by-step fashion, leveraging intermittent connections to eventually reach their intended destination [7]. Opportunistic Networks (OppNets), a subset of DTNs, emphasize the sporadic nature of communication, where nodes exploit encounters with other nodes to exchange data. OppNet protocols commonly employ store-carry-forward techniques, where nodes store messages in their buffers and relay them to other nodes when suitable opportunities arise [8] (see Figure 1). However, the limitations of supporting TCP/IP routing protocols in DTNs due to frequent disconnections and network fragmentation pose significant challenges. DTN routing protocols, although robust in highly partitioned environments, typically result in higher delays, lower delivery ratios, and increased overhead, as they rely on store-and-forward mechanisms and opportunistic forwarding [9]. To overcome these challenges and leverage the well-established efficiencies of TCP/IP protocols, the conversion of the DTN into a more connected network structure can be achieved by implementing a cluster-based routing protocol within the DTN. The core idea is to dynamically group nodes into clusters based on their connectivity and proximity. Cluster heads (CHs) are then responsible for relaying traffic within their clusters, and clusters can communicate with each other during periods of temporary network stability. This enables reliable end-to-end communication required for TCP/IP protocols [10]. This approach represents a significant enhancement in DTNs to address the practical challenges of operating in highly dynamic and disrupted environments. Nevertheless, there remain several hurdles to overcome, including the selection of cluster heads, dynamic network conditions, limited network awareness, and scalability [11]. Overcoming the aforementioned challenges necessitates the development of sophisticated, adaptive clustering routing protocols that can dynamically adjust to network conditions and minimize the end-to-end path between source and destination nodes [12].