10-08-2012, 02:49 PM
SCAM: Scenario-based Clustering Algorithm for Mobile Ad Hoc Networks
INTRODUCTION
A distributed algorithm based on (k, r) − Dominating Set is used for the selection of cluster heads and gateway nodes, here k is the minimum number of cluster heads per node in the network and r is the maximum number of hops between the node and the cluster head. From among the k dominating nodes, the nonclusterhead node can select the most qualified dominating node as its cluster head. The quality of the cluster head is calculated based on various metrics, which include connectivity, stability and residual battery power. Long-term service as cluster head depletes their energy, causing them to drop out of the network. Similarly, the cluster head with relatively high mobility than its neighbors leads to frequent cluster head election process. This perturbs the stability of the network and adversely affects the performance of the network. Load balancing among cluster heads and correct positioning of cluster head in a cluster are also vital to increase the life span of the network. The proposed algorithm periodically calculates the quality of all dominating nodes and if it goes below the threshold level it resigns the job as cluster head and sends this message to all other member nodes. Since these nodes have k dominating nodes within r − hop distance, it can choose the current best-qualified node as its cluster head. SCAM uses techniques to maintain the cluster structure as stable as possible with less control message.
Advantages:
• Clusters are created in such a way that the created clusters remain stable over a long period of time
• The selection of cluster head is based on its quality, which is a function of its degree, residual battery power and stability.
Disadvantages:
• Security is not incorporated in this approach.