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

Mobile Agents for Clustering and Routing in Mobile Ad Hoc Networks 273mobile agent uses node mobility and link characteristic related parameters for clustering.A mobile agent is capable of migrating autonomously carrying code, data and statewith itself. It can even spawn off child agents anywhere in the network, merge thequery results and send back the final result to the source node. Mobile agents canimprove bandwidth utilization, reduce communication latency, minimize connectiontime, and reduce network traffic load.An attractive application of mobile agents is processing data over unreliable networks,such as MANETs. In such an environment, the low reliability network can beused to transfer agents, rather than a chunk of data, from one node to another. InMANETs, the agents can travel to the nodes of the cluster and collect or process clusteringand routing information, without the risk of network disconnection, and thenreturn to its originating node.In order to deploy mobile agents in MANETs, a suitable mobile agent platform isneeded. Conventional mobile agent platforms such as Aglets [16], Concordia [23],and D’Agent [8], to name a few, operate within high-end desktop environments suchas Windows and Unix. As a result some research projects have recently been proposedto develop mobile agent platforms for mobile devices. The Lightweight ExtensibleAgent Platform (LEAP) [18] aims to develop a FIPA-compliant mobile agentplatform for mobile devices with services in the area of knowledge and travel management.In our research, we hope to develop our own mobile agent platforms forMANETs.3 Mobile Agents for Clustering and RoutingIn a clustered network, a cluster may be organized into a multilevel hierarchy. A hierarchicalclustering architecture can reduce network routing overhead by hiding informationabout the content of the cluster. Route maintenance procedures and routingtable length can be significantly reduced [14]. Such architecture is relatively stableand scalable due to the localized nature of route computation and can be used inMANETs. Most previous works on clustering are based on the design of algorithmsthat form a 2-hop clustering architecture. These algorithms use a single parametersuch as node ID, connectivity, signal strength, mobility, power or some combinationof these for cluster formation. The cluster formation process can be slow since themethod of gathering the information necessary for cluster formation may not be efficientif clustering with more than 2-hop architecture is desired.Since mobile agents are autonomous and intelligent entities, they can be used forcreating dynamic and adaptive clustering in MANETs [22]. Distributed route computationcan be performed at each node. The clustering architecture consists of ordinarynodes, clusterheads and gateways. In our architecture, intra-cluster and inter-clusterrouting can be carried out using reactive, proactive or hybrid routing schemes. Since asingle criterion is not sufficient for a stable and efficient cluster formation, an aggregatemetric that includes node mobility, link quality, available bandwidth, etc. will bemaintained and used for cluster formation. This metric will also be used by the clusteringagent to assess the quality of the clusterhead periodically.