Mobile Ad Hoc Networks Providing Efficient Multicasting Techniques

Multicasting is the transmission of packets to a group of zero or more hosts identified by a single destination address Multicasting is intended for group oriented computing. Typically the members of a host group are dynamic that is hosts may join and leave groups at any time T. In Mobile Ad hoc Networks communication among the groups is more important. To implement group communication we use efficient Multicast method. The implementation using efficient and scalable multicast in MANET is very difficult in group membership management and multicast packet forwarding over a dynamic topology. Several strategies have been proposed to further improve the efficiency of the protocol, for example, introducing the concept of zone depth for building an optimal tree structure and integrating the location search of group members with the hierarchical group membership management. A scheme is designed to handle empty zone problem faced by most routing protocols using a zone structure. The scalability and the efficiency of EGMP are evaluated through simulations and quantitative analysis. The simulation results demonstrate that EGMP has high packet delivery ratio, low control overhead and multicast group joining delay under all test scenarios, and is scalable for both group size and network size. Compared to Scalable Position-Based Multicast (SPBM), EGMP has significantly lower control overhead, data transmission overhead, and multicast group joining delay. INTRODUCTION An Ad hoc Network consists of a set of autonomous mobile nodes that communicate via multi-hop wireless communication in an infrastructureless environment. It is an autonomous system in which mobile nodes connected by wireless links are free to move randomly and often act as routers at the same time. Ad hoc networks have become increasingly relevant in recent years due to their potential applications in military battlefield, emergency disaster relief, vehicular communications etc. [10]. Conventional MANET multicast protocols can be described into two main categories, tree-based and mesh based. However, due to the constant movement as well as frequent network joining and leaving from individual nodes, it is very difficult to maintain the tree structure using these conventional tree-based protocols (e.g., MAODV, AMRIS, MZRP, and MZR). The mesh-based protocols (e.g., FGMP, CoreMOBILE AD HOC NETWORKS PROVIDING EFFICIENT MULTICASTING TECHNIQUES Dudekula Yasmine and V.Subbaramaiah 374 Assisted Mesh protocol, ODMR) are proposed to enhance the robustness with the use of redundant paths between the source and the destination pairs [9]. Conventional multicast protocols generally do not have good scalability due to the overhead incurred for route searching, group membership management, and creation and maintenance of the tree/mesh structure over the dynamic MANET. For MANET uni-cast[4] routing, geographic routing protocols have been proposed in recent years for more scalable and robust packet transmissions. The existing geographic routing protocols generally assume mobile nodes are aware of their own positions through certain positioning system, and a source can obtain the destination position through some type[6] of location service an intermediate node makes its forwarding decisions based[9]. on the destination position inserted in the packet header by the source and the positions of its one-hop neighbors learned from the periodic beaconing of the neighbors. By default, the packets are greedily forwarded to the neighbor that allows for the greatest geographic progress to the destination. When no such a neighbor exists, perimeter forwarding is used to recover from the local void, where a packet traverses the face of the planarized local topology sub-graph by applying the right-hand rule until the greedy forwarding can be resumed. Similarly[4], to reduce the topology maintenance overhead and support more reliable multicasting, an option is to make use of the position information to guide multicast routing. However, there are many challenges in implementing an efficient and scalable geographic multicast scheme in MANET[6]. For example, in uni-cast geographic routing, the destination position is carried in the packet header to guide the packet forwarding, while in multicast routing, the destination is a group of members. A straight-forward way to extend the geography-based transmission from uni-cast to multicast is to put the addresses and positions of all the members into the packet header, however, the header overhead will increase significantly as the group size increases, which constrains the application of geographic multicasting only to a small group. Besides requiring efficient packet forwarding[4], a scalable geographic multicast protocol also needs to efficiently manage the membership of a possibly large group, obtain the positions of the members and build routing paths to reach the members distributed in a possibly large network terrain. The existing small-groupbased geographic multicast protocols normally address only part of these problems. ODMRP (On Demand Multicast Routing Protocol) [6] is proposed to enhance the robustness with the use of redundant paths between the source and the destination pair’s scalability due to the overhead incurred for route searching, group membership management, and creation and maintenance of the tree/mesh structure over the dynamic MANET. We introduce zone-supported geographic forwarding to reduce the routing failure, and provide mechanism to handle zone partitioning. In addition, we introduce a path optimization process to handle multiple paths, and provide a detailed cost analysis to demonstrate the scalability of the proposed routing scheme [4]. Techniques used for providing efficient and scalable multicast: 1. Efficient Geographic Multicast Protocol EGMP supports scalable and reliable membership management and multicast forwarding through a two-tier virtual zonebased structure. At the lower layer, in reference to a pre-determined virtual origin, the nodes in the network self-organize themselves into a set of