A Mobile ad hoc network (MANET) is a selfconfiguring network of mobile devices connected by wireless links. The communication in ad hoc network is uncertain because established route could be broken anytime. The main two reasons for route breakage are: movement of a node in the route from its neighbor's signal range and any node in the route may run out of battery. In this paper, we have proposed a scheme E-DSR that improves the route maintenance process of DSR. E-DSR uses two levels of thresholds, each of two factors: node's battery power and received RF signal power. During the time interval between these two thresholds, source node checks the freshness of the entire backup routes simultaneously and delete stale routes from its route cache. If the route cache becomes empty then source initiate a new route discovery. The advantage of E-DSR is that the time interval (T) would be zero when there is at least one fresh route in the source's route cache and T would be much less than that in DSR when there is no fresh route found. Hence, E-DSR minimizes the loss of data packets.

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Abstract.A MANET is a self-configuring network of mobile devices connected by wireless links. Reactive Routing protocols for MANETs flood RREQ control packets to discover and establish route between the sourcedestination pairs. This situation becomes worse and degrades the network performance whenever several connections need to be established simultaneously. This paper proposes a mechanism to minimize the routeestablishment overhead in AODV by controlling the flooding of RREQ packets. In brief, each intermediate node counts the number of RREQ packets flooded by it and if the count exceeds a threshold, stops further flooding. On the other hand, an intermediate node, after getting a RREP packet within reverse-routelifetime reduces the counter value; otherwise the reverse link in its cache is removed along with the reduction of the counter value. The proposed scheme has been simulated using ns-2 and compared with the original AODV and it has been found that it enhances network performance.

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