Routing in MANETs, where mobile nodes function as end nodes as well as routers, is a difficult task since topology in these networks is inherently dynamic. Based on conventional routing algorithms in wired networks, proactive routing protocols [6, 7, 9] solve the routing problem in MANETs by proactively exchanging update messages to establish routes to all nodes of the network. Unfortunately, proactively setting up all routes may not be a suitable routing strategy for MANETs since smartly reacting to any change in the network topology is very hard. This motivates another routing strategy, reactive routing strategy, which setup routes only when nodes need routes to send data. However, the flood-based route discovery required by reactive routing protocols is problematic and have not been completely solved.
In this thesis, we propose $\emph{Lazy Topology Exchange (LTE)}$ and $\emph{Condition Bearing Route Discovery (CBRD)}$ to solve the route discovery problem in reactive routing protocols. In essence, LTE is a lazy update proactive routing protocol that sets up and maintains an approximate network topology representation at each node, and CBRD is a route discovery mechanism which employs LTE to localize query area around the shortest path to the destination. Our simulations have shown that LTE and CBRD efficiently reduce route discovery overhead as well as route discovery delay, and also they improve routing performance of flooding dependent reactive routing protocols like AODV in low- and moderate-traffic networks.
