IOSR Journal of Electronics and Communication Engineering (IOSR-JECE) e-ISSN: 2278-2834,p- ISSN: 2278-8735.Volume 9, Issue 4, Ver. V (Jul - Aug. 2014), PP 07-12 www.iosrjournals.org www.iosrjournals.org 7 | Page A New Scheme of Routing in Mobile Ad hoc Networks for Reducing Delay and Finding Shortest Path Radhu. R. Nair (Communication Systems, Dhanalakshmi Srinivasan College of Engineering/ Anna University Chennai, India) Abstract : Wireless networks offer more flexibility and adapt easily to changes in the configuration of the network. Wireless ad hoc network is a decentralized type of wireless network. Mobile ad hoc network is a type of ad hoc network, in which each and every node can change its location. Frequent link breakages exist due to its high mobility of nodes which leads to frequent path failures and route discoveries. An efficient and fundamental data dissemination mechanism is broadcasting, the mobile node blindly rebroadcasts the first received route request, even if there is no route to destination leads to broadcast storm problem.. In this paper a hybrid protocol is proposed, which combines the advantages of neighbor coverage based probabilistic rebroadcast protocol and adhoc on demand distance vector routing protocol and is simulated by Network Simulator. The neighbor coverage and probabilistic mechanism significantly decreases the number of retransmissions so as to reduce the routing overhead. Adhoc on demand distance vector routing protocol finds the shortest path to destination by evaluating the hop count. The shortest path reduces the average end to end delay more effectively. Thus hybrid protocol improves the routing performance. Keywords: Rebroadcast delay, rebroadcast probability, connectivity factor, additional coverage ratio, shortest path I. Introduction A Mobile Ad-hoc Network (MANET) is a dynamic wireless network that can be formed without the need for any pre-existing infrastructure in which each node can act as a router. Mobile ad hoc network (MANET) is an autonomous system of mobile nodes connected by wireless links. Each node operates not only as an end system, but also as a router to forward packets [5]. The nodes are free to move about and organize themselves into a network. These nodes change position frequently. However, due to node mobility in MANETs, frequent link breakages may lead to frequent path failures and route discoveries. It increases the overhead of routing protocols which reduces the packet delivery ratio and also increases the end-to-end delay [1]. Thus, reducing the routing overhead in route discovery is an essential problem. The conventional on demand routing protocols use flooding to discover a route. They broadcast a Route Request (RREQ) packet to the networks, and the broad casting induces excessive redundant retransmissions of RREQ packet. In traditional protocol the route from the source to destination is selected on the basis of hop counts and sequence number. The route which has minimum number of hop counts and highest sequence number will be selected as the best route. The sequence numbers tells us the freshness of the route [2]. The long standing feature of routing protocols in Mobile Ad hoc Network (MANET) send periodic messages to realize the changes in topology. The traditional routing protocols in MANETs send periodic messages to realize the changes in topology of mobile ad hoc network. When compared to reactive routing protocols, the Proactive routing protocols causes high routing overhead and the broadcasting of messages causes broadcast storm problem [4]. Proactive protocols disseminate routing information from each node to each other periodically, and find routes continuously, whereas reactive protocols find routes on demand, i.e. only when a source sends information for forwarding to a destination. Without a fixed infrastructure the mobile nodes in MANETs can be dynamically self-organized into arbitrary topology networks. Thus MANETs are suitable for emergency situations like natural or human-induced disasters, military conflicts, emergency medical situations, etc because of its random topology. Using random mobility model, the nodes in Mobile Ad hoc Network can get the service to communicate each node in network [1]. The proposed hybrid protocol is combines the advantages of neighbor coverage based probabilistic rebroadcast protocol (NCPR) and ad hoc on demand distance vector routing protocol l(AODV). The neighbor coverage based probabilistic rebroadcast protocol, exploits the neighbor coverage knowledge by rebroadcast delay and thus obtains additional coverage ratio. Connectivity factor is defined and it is combined with additional coverage ratio to set rebroadcast probability. Ad hoc on demand distance vector routing protocol finds the shortest path to destination by evaluating the hop count. Thus hybrid protocol improves the routing performance.