**1. Introduction**

Ad-hoc network is a collection of wireless mobile nodes dynamically forming a temporary network without the aid of any established infrastructure or centralized administration. Routing protocols in mobile ad-hoc network helps node to send and receive packets. In this chapter our focus is to study Reactive (AODV and A-AODV), Proactive (DSDV) based on Random Waypoint mobility model. In this chapter, a new routing protocol A-AODV is proposed. The performance of three routing protocols (AODV, DSDV, and A-AODV) based on metrics such as packet delivery ratio, end to end delay, and throughput are studied. The simulation work is done with the NS-2.34 simulator with the ordered traffic load.

Mobile ad-hoc networks, also known as short-lived networks, are autonomous systems of mobile nodes forming network in the absence of any Centralized support. This is a new form of network and might be able to provide services at places where it is not possible otherwise. Absence of fixed infrastructure poses several types of challenges for this type of networking. Among these challenges is routing, which is responsible to deliver packets efficiently to mobile nodes. So routing in mobile ad-hoc network is a challenging task due to node mobility. Moreover bandwidth, energy and physical security are limited. MANET is the Art of Networking without a Network. In the recent years communication technology and services have advanced. Mobility has become very important, as people want to communicate anytime from and to anywhere. In the areas where there is little or no infrastructure is available or the existing wireless infrastructure is expensive and inconvenient to use, Mobile Ad hoc NETworks, called MANETs, are useful. They form the integral part of next generation mobile services. A MANET is a collection of wireless nodes that can dynamically form a network to exchange information without using any preexisting fixed network infrastructure.

Each device in a MANET is free to move independently in any direction, and will therefore change its links to other devices frequently. Each must forward traffic unrelated to its own use, and therefore be a router. The primary challenge in building a MANET is equipping each device to continuously maintain the information required to properly route traffic. Such networks may operate by themselves or may be connected to the larger Internet.
