Designing a Simulation Application for Mobility Based Clustering Algorithm in MANETS

Abstract

A wireless ad-hoc network is a self-configuring network that does not depend on any infrastructure for communication. Every node is free to move anywhere in the network and data is exchanged independently across the network. Destruction of one node does not affect the communication of other nodes in the network. Every node in the network can act as both host as well as destination. A wireless ad-hoc network does not rely on fixed infrastructure or predetermined connectivity. It is a self organizing multi-hop wireless network in which all of the nodes can be mobile. Data is exchanged between nodes via wireless communication. Aside from the ability to be rapidly deployed, wireless ad-hoc networks have the ability to exist in highly volatile environments. Unlike traditional networks, if one node is destroyed it will not impact the data exchange between the remaining nodes within the network. The selection of the correct network topology given the network characteristics is extremely important to ensure reliable and efficient communication between nodes. The topology of a network can be either hierarchical or flat. In a hierarchical topology nodes are divided into clusters. Within each cluster, a cluster head is selected via a mathematical formulation or heuristic method. Cluster heads are responsible for keeping track of which nodes are maintained in their respective cluster. Furthermore, they are responsible for transmitting data between clusters. Each of the cluster heads maintains a continuously updated routing table. This table contains specific information detailing which cluster each node belongs to. If a node desires to transfer information to another node, the information is sent to the sending node’s cluster head. This cluster head scans its routing table to determine which cluster the recipient is in. If the recipient is in the same cluster, the data is immediately forwarded to the receiving node. If not, the cluster head scans its routing table to determine which cluster the recipient is in and forwards the data to the appropriate cluster head where it is again forwarded to the recipient. Mobility based Clustering algorithm uses mobility of the nodes as a feature to form the clusters. Each node in the Mobile Ad hoc Network computes the ratio of two successive “Hello” messages from all its neighbors. This gives the relative mobility metric of the nodes with respect to their respective neighbors. Then by calculating the variance of relative mobility values of all the nodes with respect to their neighbors in a distributed manner, the aggregate speed of all the mobile nodes can be estimated. Finally, the mobile node with lowest variance value in its neighborhood is elected as the cluster head. MOBIC is suitable for MANETs in which a group of mobile nodes moves with almost similar speed and the direction. However, if mobile nodes move randomly and change their speeds from time to time, the performance of this algorithm is degraded.