This paper explores the impact of node mobility on distributed and mobility adaptive clustering (DMAC), a typical clustering protocol for mobile ad hoc networks. In particular, in this paper we evaluate the cost of maintaining the DMAC clustering structures when the nodes move according to three different mobility models, namely, the random way point model, the Brownian motion and the Manhattan mobility model. Via ns2-based simulations, we have observed that the mobility models have different impact on protocol performance. The general trend, however, appears to be the same for networks of increasing size. The second contribution of this paper concerns investigating ways of mitigating the impact of mobility on the clustering structure and hence over the overall network performance. We consider a generalization of DMAC (GDMAC) where rules are established to decrease the number of cluster updates. Via simulation we have observed that GDMAC is effective in reducing the clustering overhead imposed by mobility, and the corresponding maintenance cost.Among the crucial challenges posed by the ad hoc architecture, there is that of defining scalable protocols. As in the case of wired networks, hierarchical approaches have been proposed for routing that make possible to 'simplify' the overall network topology now seen as a set of clusters. Nodes are partitioned into groups, each with a clusterhead that coordinates the cluster formation process and some ordinary nodes which rely on the clusterhead for inter-cluster communications. The idea common to basically all clustering protocols is to cluster together nodes that are in physical proximity, thereby providing the network with a hierarchical organization which is smaller in scale, and hence simpler to manage.Clustering for ad hoc networks has been widely investigated and a host of solutions are available. Thorough surveys of ad hoc clustering protocols, as well as

This paper explores the impact of node mobility on DMAC, a typical clustering protocol for mobile ad hoc networks. Several protocols for clustering have been proposed, which are quite similar in operations and performance. We selected one and evaluate the cost of maintaining the clustering structures when the nodes move according to three different mobility models, namely, the random way point model, the Brownian motion and the Manhattan mobility model. Via ns2-based simulations we have observed that the mobility models have different impact on protocol performance. The general trend, however, appears to be the same for networks of increasing size. The second contribution of this paper concerns mitigating the impact of mobility over the clustering structure and hence on the overall network performance. We consider a generalization of DMAC (GDMAC) where rules are established to decrease the number of cluster updates. Via simulation we have observed that GDMAC is effective in reducing the clustering overhead imposed by mobility, and hence its maintenance cost.