Implementation of Routing Algorithms in Adhoc Area Networks
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IMPLEMENTATION OF ROUTING ALGORITHMS IN ADHOC AREA NETWORKS
The wireless arena has been experiencing exponential growth in the past decade. There have been great advances in network infrastructures, growing availability of wireless applications,
and the emergence of omnipresent wireless devices such as portable or handheld
computers, PDAs, and cell phones, all getting more powerful in their capabilities.Mobile users can rely on their cellular phone to check e-mail and browse the Internet; travelers with portable computers can surf the internet from airports, railway stations, cafes, and other public locations; tourists can use GPS terminals installed inside rental cars to view driving maps and locate tourist attractions; files or other information can be exchanged by connecting portable computers via wireless LANs while attending conferences; and at home, a family can synchronize data and transfer files between portable devices and desktops.
For all of these reasons, combined with significant advances in technology and standardization,new alternative ways to deliver connectivity have been gaining increased attention in recent years. These are focused around having mobile devices within the transmission range connect to each other through automatic configuration, setting up an ad hoc mobile network that is both flexible and powerful. In this way, not only can mobile nodes communicate with each other, but also receive Internet services through an Internet gateway node, effectively extending both network and Internet services to noninfrastructure areas. As the wireless network continues to evolve, this ad hoc capability will become more important, and the technology solutions used to support it more critical, spurring a host of research and development projects and activities in industry and academia alike.
On the basis of network formation and architecture, wireless networks can be dividedinto two broad categories based on how the network is constructed and the underlining network architecture:
1. Infrastructure-based network. A network with preconstructed infrastructure that is made of fixed and wired network nodes and gateways, with, typically, network services delivered via these preconfigured infrastructures. For example, cellular networks are infrastructure-based networks built from PSTN backbone switches, MSCs, base stations, and mobile hosts. Each node has its specific responsibility in the network, and connection establishment follows a strict signaling sequence among the nodes. WLANs typically also fall into this category.
2. Infrastructureless (ad hoc) network. In this case a network is formed dynamically through the cooperation of an arbitrary set of independent nodes. There is no prearrangement regarding the specific role each node should assume. Instead, each node makes its decision independently, based on the network situation, without using a preexisting network infrastructure. For example, two PCs equipped with wireless adapter cards can set up an independent network whenever they are within range of one another. In mobile ad hoc networks, nodes are expected to behave as routers and take part in discovery and maintenance of routes to other nodes.
MOBILE AD HOC NETWORKS:
In general, mobile ad hoc networks are formed dynamically by an autonomous
system of mobile nodes that are connected via wireless links without using an
existing network infrastructure or centralized administration. The nodes are free to move randomly and organize themselves arbitrarily; thus, the networkÐŽ¦s wireless topology may change rapidly and unpredictably. Such a network may operate in a standalone fashion, or may be connected to the larger Internet. Mobile ad hoc networks are infrastructureless networks since they do not require any fixed infrastructure such as a base station for their operation. In general, routes between nodes in an ad hoc network may include multiple
hops and, hence, it is appropriate to call such networks ÐŽ§multihop wireless ad hoc networks.ÐŽÐ An ad hoc network might consist of several home-computing
devices, including notebooks, handheld PCs, and so on. Each node will be able to communicate directly with other nodes that reside within its transmission range. For communicating with nodes that reside beyond this range, the node needs to use intermediate nodes to relay messages hop by hop.
CHARACTERISTICS OF MOBILE AD HOC NETWORKS:
MANETs inherit common characteristics found in wireless networks in general, and add
characteristics specific to ad hoc networking:
_ Wireless: Nodes communicate wirelessly and share the same media (radio, infrared,
etc.).
_ Ad-hoc-based: A mobile ad hoc network is a temporary network formed dynamically
in an arbitrary manner by a collection of nodes as need arises.
_ Autonomous and infrastructureless: MANET does not depend on any established
infrastructure or centralized administration. Each node operates in distributed peerto-
peer mode, acts as an independent router, and generates independent data.
_ Multihop routing: No dedicated routers are necessary; every node acts as a router
and forwards each othersÐŽ¦ packets to enable information sharing between mobile
hosts.
_ Mobility: Each node is free to move about while communicating with other nodes.
The topology of such an ad hoc network is dynamic in nature due to constant movement
of the participating nodes, causing the intercommunication patterns among
nodes to change continuously.
Ad hoc wireless networks eliminate the constraints of infrastructure and enable devices
to create and join networks on the fly-any time, anywhere-for virtually any application.
DESIGN ISSUES AND CONSTRAINTS:
1) They are Infrastructureless: Mobile ad hoc networks are multihop infrastructureless wireless networks. This lack of fixed infrastructure in addition to being wireless, generate new design issues compared with fixed networks. Also, lack