Ad-hoc networks have opened a new dimension in wireless networks. It allows wireless nodes to communicate in absence of centralized support. It doesn‟t always follow any fixed infrastructure due to high mobility of nodes and multipath propagations. It is highly deployable, self configurable and has dynamically changing topologies. It may connect hundreds to thousands of mobile nodes. Routing protocols of mobile ad-hoc networks differ from the existing internet protocols which are designed for the fixed structure based wireless networks. MANET protocols have to face high challenges due to dynamically changing of topologies, low transmission power and asymmetric links. Due to link instability, node mobility and frequently changing topologies routing becomes one of the core issues in MANETs. A suitable and effective routing mechanism helps to extend the successful deployment of mobile ad-hoc networks. Currently existent routing protocols provide routing solutions up to a certain level and most of them are designed and implemented in small areas. Many researchers are still working on the developments of MANET routing protocols. In our thesis, we are going to concentrate on DSDV , AODV , TORA, LDR and ZRP routing.
1.1 INTRODUCTION TO MANET
Wireless networks are playing a major role in the area of communication. Now we are using wireless networks in military applications, industrial applications and even in personal area networks. Previously, the main difference between wireless and wired networks was only in communication channel. There exist physical medium in wired networks, while on the other side physical medium doesn‟t exist on the wireless networks. Wireless networks became very popular in different applications considering the following factors: ease of installation, reliability, cost, bandwidth, total required power, security and performance of network . All networks were however based on fixed infrastructures. Most common infrastructure based wireless networks are cordless telephone, cellular networks, Wi-Fi, Microwave communication, Wi-MAX, Satellite communication and RADAR etc. Next generation wireless ad-hoc networks are playing a prominent role in the rapid deployment of independent mobile users, efficient and dynamic communication for emergency/rescue operations, disaster relief efforts, and military networks. Ad-hoc networks do not have fix topologies to cover a large area. These topologies may change dynamically and unpredictably. Traditional routing protocols that are normally used for internet based wireless networks. These can‟t be applied directly to ad-hoc wireless networks; because some common assumptions are not valid in all cases for such dynamically changing networks and may be not true for mobile nodes. The 2 availability of bandwidth is an important issue of ad-hoc networks. Thus, these network types present a difficult challenge in the design of routing protocols, where each node participates in routing by forwarding data dynamically based on the network connectivity. It improves the scalability of wireless networks compared to infrastructure based wireless networks because of its decentralized nature. In critical situations: natural disasters, military conflicts or any emergency moment, ad-hoc networks are best suited due to minimal configuration and quick operation. Ad-hoc networks can be classified in three categories based on applications; Mobile Ad-hoc Networks (MANETs), Wireless Mesh Networks (WMNs), Wireless Sensor Networks (WSN). A MANET is an autonomous collection of mobile nodes . A network is decentralized when the network organization and message delivery are executed by mobile nodes. The routing functionality is furthermore integrated into the mobile nodes. Nodes are struggling with the effects of radio communication, including multi-user interferences, multipath fading, and...