1.1 Mobile Ad Hoc Network Prologue
In a Mobile Ad Hoc Network, nodes move arbitrarily or randomly, hence the network may familiar with rapid and unpredictable topology changes. Routing paths in Mobile Ad Hoc Network are potentially holding multiple hops, and every node in Mobile Ad Hoc Network has the responsibility to act as a router. Routing in MANET has been an exigent task ever for the wireless networks came into existence. The key reason for this is the invariable change in network topology as a result of high degree of node mobility. A number of protocols have been developed to carry out such kind of task (David B. Johnson, 1994).
An ad-hoc wireless network is a compilation of wireless nodes that self organize into a network without the help of an existing infrastructure. Some or probably all of these nodes are mobile (Jain et al., 2005). Since the network can be deployed swiftly and flexibly, it is attractive to numerous potential applications. A Mobile ad hoc network (MANET) is an autonomous collection of mobile users (nodes) that communicate over bandwidth constrained wireless links as shown in Figure 1.
Because of nodal mobility, the network topology might be change rapidly and impulsively over time to time. The network is decentralized, where network association, connection and message delivery must be executed by the nodes themselves. Message routing could be a problem in a decentralized environment where the topology fluctuates and changes. While the shortest path from a source to a destination based on a given cost function in a static network is usually the optimal route, this concept is difficult to extend in Mobile Ad hoc Network. MANET ad hoc nodes present in range of different areas. Factors such as power expended, variable wireless link quality, circulation path loss, fading, multi-user interference, and topological changes, limited bandwidth become appropriate issues. The network should be able to adaptively modify and adjust routing paths to improve any of these properties (Meghanathan, 2011).
E.g.: Possible commercial applications of Mobile Ad hoc Network include business links sharing information during a conference and meeting, students using laptop computers to participate in an interactive sessions, and emergency disaster relief employees coordinating efforts in natural disasters. Mobile ad hoc networks also a good substitute in rural areas or third world countries where basic communication infrastructure is not well recognized.
1.2 Homogenous and Heterogeneous Mobile Ad hoc Network
Most of current routing protocols suppose homogeneous network environment where all nodes have the same capabilities and resources. Although homogenous network are simple and straight forward to model and analysis, they exhibits poor scalability compared with heterogeneous networks that consist of different nodes with different resources. Heterogeneous Mobile Ad Hoc Network comprise of mobile devices as Figure.2 that have different communications potential capacity such as radio range, battery life, data transmission rate, etc (Tamilselvan & Shanmugam, 2010).
Figure 2.
Heterogenous mobile network