Rough Set Based Ad Hoc Network: A Review

1. Introduction

The basic requirement of modern communication system is unlimited mobility, from this requirement the concept of mobile communication is coming. There are two types mobile communication network is considered one is foxed infrastructure network and a second one is infrastructure-less network where no fixed backbone is present. Mobile ad hoc network is the example of infrastructure-less networks. Here the network consists of ad hoc nodes and all the nodes acts as routers and as well as hosts. Anywhere and anytime communication is possible in this network and the communication is done by multi-hop transmission. There are two types of wireless networking- Infrastructure networking and Ad hoc networking. A fixed and wired backbone is present in infrastructure networking. Here the mobile communicates directly to an access point. This cellular network is perfect for the area where access points can be stationed. But ad hoc network has no base stations, means it is infrastructure less or it has multi hop. It is a collection of more than one device which is equipped with the wireless communications and network capability. It supports the computing anytime and anywhere. In ad hoc each mobile host acts as a router and supports peer-to-peer and peer-to-remote communications. It also reduced the administrative cost.

Figure 1 depicts a peer-to-peer, multi hop ad hoc network. Here the mobile node A directly communicates with single hop B whenever the channel is available. If the channel is not available, then the multi hop communication is necessary like[INSERT FIGURE 001]. To work in the multi hop communication, the intermediate nodes should route packet like a router. For the mobile ad hoc networks (MANETs), the routing packet between any pair of nodes is a challenging task. It is mainly because the nodes can move randomly throughout the network. An approach that was accounted optimal at a specific point in time might not work at all in other situations. Furthermore, the stochastic attributes of the wireless channels add to the unpredictability of path quality. The operating environment as such might also create complication for indoor situations - as the closing of a door might cause a path to be disrupted. Traditional routing protocols are proactive in that they maintain routes to all nodes, including nodes to which no packets are being sent. They respond to any difference in the topology even if no traffic is affected by the change, and they need periodic control messages to maintain routes to every node in the network. The rate at which these control messages are sent must display the dynamics of the network in order to maintain authentic routes.

Figure 1.

Ad hoc routing

The main challenge in MANET is routing. The research is going on in the field of the shortest path algorithm from source to destination by applying different methods. There exist a large number of routing paths from source to destination node for the data transfer. A packet can travel from the source to destination either directly or through the same set of intermediate packet which forwarding the nodes. Within the ad hoc network the routing protocols between any pair of nodes may be difficult. It is because the random movements of the nodes and also can join or leave the network. The ad hoc networks are highly vulnerable to the security attacks and dealing with this is a challenging task for the developers also. As the rough set theory effectively deals with vagueness and uncertainty information, so the rough set routing in ad hoc network is more acceptable instead of the standard routing.