Page 2 Lecture Notes in Computer Science 2865 Edited by G. Goos ...

272 M.K. Denko and Q.H. MahmoudAn important area of research is the application of mobile agents in mobile andwireless networks. A mobile agent is a software entity that can actively migrateamong nodes in a heterogeneous network interacting with other agents and serviceagents [9]. This is ideal for MANETs because mobile agents are capable of supportingasynchronous communication. As a result, several mobile agent-based projectshave been proposed. For example, a mobile agent-based routing protocol has beenrecently proposed in [19]. The protocol uses the combined benefits of traditional antbasedadaptive routing and the Ad-Hoc on Demand Distance Vector (AODV) routingprotocol to maintain node connectivity and perform routing.In this paper, we propose a mobile agent-based method for clustering and routingin MANETs. In this method, mobile agents are used to maintain clustering and routinginformation at each node in a distributed manner. The information maintained inthe routing table is used for intra-cluster and inter-cluster routing. Inter-clustering isperformed via the clusterhead.The rest of this paper is organized as follows. Section 2 describes the benefits ofclustering and mobile agents in MANETs. Section 3 presents the proposed agentbasedclustering and routing method. Finally, conclusions and future research workare presented in Section 4.2 Clustering and Mobile Agents in MANETsClustering is the partitioning of the network into small manageable groups of nodes.Clustering offers several advantages in mobile ad hoc networks. First, network partitioningimproves routing and mobility management [21]. It increases system capacity,reduces signaling and control overhead and minimizes network congestion. Thismakes the network more scalable and as a result can support a larger network size.Second, clustering stabilizes the network topology and provides a virtual infrastructurefor a dynamic network. The clusterhead acts as a base station for its cluster.Third, clustering helps to perform more efficient resource allocation. By assigningdifferent codes to each cluster, MAC resource management can be improved andwireless channels can be used efficiently [1, 7]. It also provides good power managementmechanisms. Clusters can be either distinct or overlapping. In the former, eachnode belongs to only one cluster while in the latter the neighboring clusters can have acommon node (gateway or access point) between them. In this paper we consider onlydistinct clusters.Several clustering algorithms have been proposed in the literature for groupingnodes into clusters [1, 2, 3, 7, 14, 17]. One of the earliest clustering algorithms is theLinked Cluster Algorithm (LCA) [1] proposed for mobile radio networks. The algorithmuses a distributed control mechanism for neighbor discovery and cluster formation.In this algorithm a node with the lowest ID becomes a clusterhead. In [7], theLowest-ID (LID) and another distributed clustering algorithm known as Highest-Connectivity (HC) were used for clustering nodes in a multicluster, multihop packetradio network architecture. In the HC algorithm, a node with the highest degree iselected as a clusterhead. A clustering algorithm that combines the LID and HC clusteringalgorithms was proposed in [2]. The experimental results indicated that thealgorithm generates a lower number clusterheads and gateways. In our approach, the