Influence of periodic control messages on the Performance of Mobile Ad Hoc NETworks (MANET)

Clustering is an important research area for mobile ad hoc networks (MANETs) as it increases the capacity of network, reduces the routing overhead and makes the network more scalable in the presence of both high mobility and a large number of mobile nodes. In cluster or hierarchical structure local connectivity knowledge of mobile nodes is necessary for the formation and maintenance of cluster. For determining and maintaining local connectivity information, MANET utilizes periodic control messages commonly known as hello messages. A reception of hello message indicates the presence of a neighbor. This results in at least one hello message broadcast during every time period. Frequent exchange of hello messages cause considerable overhead, which consume considerable bandwidth and drain mobile nodes energy quickly, likely cause congestion, collision and data delay in larger networks. Overhead due to periodic hello messages is a function of two variables, namely, number of nodes in networks and hello interval which is the maximum time interval between the transmissions of control messages. Changing the variables affect the number of hello messages transmitted and hence the overhead. This paper uses an implementation of Cluster Based Routing Protocol (CBRP) to examine the influence of periodic hello messages on the performance of mobile ad hoc networks by keeping the number of nodes constant and varying the hello interval. Packet delivery fraction, average end to end delay, normalized routing load, channel utilization and control overhead are evaluated by varying mobility and hello interval to show the effect of control messages.