Classification and Comparative Study of Routing Techniques in Adhoc Wireless Networks

Wireless systems have been in use since 1980s. We have seen their evolutions to first, second and third generation's wireless systems. Wireless systems operate with the aid of a centralized supporting structure such as an access point. These access points assist the wireless users to keep connected with the wireless system, when they roam from one place to the other. The presence of a fixed supporting structure limits the adaptability of wireless systems. In other words, the technology cannot work effectively in places where there is no fixed infrastructure. Future generation wireless systems will require easy and quick deployment of wireless networks. This quick network deployment is not possible with the Infrastructured wireless systems. Recent advancements such as Bluetooth introduced a new type of wireless systems known as ad-hoc networks. Ad-hoc networks or "short live" networks operate in the absence of fixed infrastructure. They offer quick and easy network deployment in situations where it is not possible otherwise. Ad-hoc is a Latin word, which means "for this or for this only." Mobile ad-hoc network is an autonomous system of mobile nodes connected by wireless links; each node operates as an end system and a router for all other nodes in the network. Nodes in ad-hoc network are free to move and organize themselves in an arbitrary fashion. Each user is free to roam about while communication with others. The path between each pair of the users may have multiple links and the radio between them can be heterogeneous. This allows an association of various links to be a part of the same network. A mobile ad-hoc network is a collection of mobile nodes forming an ad-hoc network without the assistance of any centralized structures. These networks introduced a new art of network establishment and can be well suited for an environment where either the infrastructure is lost or where deploy an infrastructure is not very cost effective. The popular IEEE 802.11 "WI-FI" protocol is capable of providing ad-hoc network facilities at low level, when no access point is available. However in this case, the nodes are limited to send and receive information but do not route anything across the network. Ad-hoc networks can operate in a standalone fashion or could possibly be connected to a larger network such as the Internet. An ad-hoc network has certain characteristics, which imposes new demands on the routing protocol. The most important characteristic is the dynamic topology, which is a consequence of node mobility. Nodes can change position quite frequently; the nodes in an ad-hoc network can consist of laptops and personal digital assistants and are often very limited in resources such as CPU power, storage capacity, battery power and bandwidth. This means that the routing protocol should try to minimize control traffic, such as periodic update messages. The Internet Engineering Task Force currently has a working group named Mobile Ad-hoc Networks that is working on routing specifications for ad-hoc networks. This M.Phill thesis evaluates some of the protocols put forth by the working group. This evaluation is done by means of simulation using Network simulator 2 from Berkeley. This work aims at classification of the existing routing protocols of adhoc wireless networks using some definite parameters. After classification of routing protocols of adhoc wireless network, their comparative study was undertaken in order to yield category wise distribution. Furthermore performance evaluation of these protocols was carried out by employing different parameters like fading models, mobility models, traffic patterns etc using the network simulator NS-2 Hence I explore and evaluate different methods for validation of ad hoc routing protocols which are used to set up forwarding paths in spontaneous networks of mobile/Adhoc devices to accomplish the above mentioned comparative study and classification