MANET PROTOCOLS

Guided ByMr.P.Phani Ram Prasad

Presented ByNeelima.K3BR06CS016

OVERVIEW

INTRODUCTION

FEATURES OF MANET

USES OF MOBILE AD HOC NETWORKS

ROUTING IN MANET

ROUTING PROTOCOLS IN AD HOC WIRELESS NETWORKS

PROBLEMS IN MANET

ADVANTAGES AND DISADVANTAGES

CONCLUSION

REFERENCES

INTRODUCTION

Mobile ad-hoc network (MANET) is an autonomous system of mobile nodes, a kind of a wireless network where the mobile nodes dynamically form a network to exchange information without utilizing any pre-existing fixed network infrastructure.

Each mobile node of an ad-hoc network operates as a host as well as a router

It is a self-configuring network of nodes and routers connected by wireless links, which in synchronization form a dynamic topology.

MOBILE ADHOC NETWORK

FEATURES OF MANET

Dynamic Topologies: Nodes are free to move arbitrarily is typically multi hop may change

randomly and rapidly at unpredictable times.

Bandwidth-constrained, variable capacity links: Wireless links will continue to have significantly lower capacity than

their hard-wired counter parts.

Power-constrained operations: Some or all the nodes in a MANET rely on batteries for their

energy

Limited physical security: Mobile wireless networks are generally more prone to physical security threats than fixed, hard- wired networks.

USES OF MOBILE AD HOC NETWORKS

EXTENDING COVERAGE: Ad Hoc networks can be used for extending the coverage area of an

access point.

COMMUNICATING WHERE NO INFRASTRUCTURE EXISTS: Ad Hoc networks can also be used in an environment where no

infrastructure exists. A good example is when an army is deploying into a destroyed place or an empty space.

COMMUNITY NETWORKS:  A community network is a network where everybody shares its

connections with other people. The most famous example of community network is FON. FON is a Spanish company, sponsored by Skype and Google, who want to establish a worldwide community network.

Routing in MANET

Routing is the process of exchanging packets of information between nodes in network. Packets are sent via the communication channels from source to the destination. That connection between source and destination is called route or path.

The route is composed of at least two nodes; the source which is the node that initiates the communication and the destination which is the target to receive the communication.

A type of network is determined by many aspects, including: number of nodes participating in the network, equipment used as node, area on which the network is implemented.

Wireless networks also have their particular routing protocols.

Routing Protocols In Ad hoc Wireless networks

Routing protocols in ad hoc networks vary depending on the type of the network. Typically, ad hoc network routing protocols are classified into three major categories.

Contd…

Contd….

PROACTIVE PROTOCOL

proactive protocols are constantly updating their routing tables in order to be ready when data has to be sent, they are called table-driven protocols.

This type of protocol is close to wired networks where the same mechanisms are used in order to take routing decisions.

These mechanisms are used for finding the shortest path across the network topology; it can be the “Link state” method or the “Distance Vector” method. With the “Link State” method.

Contd….

REACTIVE PROTOCOLS Proactive protocols define a best path through the topology for

every available node. This route is saved even if not used. Reactive protocols are the most advanced design proposed for

routing on Ad-Hoc networks. They define and maintain routes depending on needs.

HYBRID PROTOCOLS Hybrid protocols tend to merge advantages of reactive and proactive

protocols. Their aim is to use an “On Demand” route discovery system, but, with a limited research cost.

Problems In Manet

SECURITY

Because the signal is diffused in the air, everybody is able to receive it. This is a major problem for security. If people have the correct equipment for a specific signal, they are able to use it.

Using a wireless communication is equivalent to shouting information from the top of a roof. One of the most effective ways for securing a wireless signal is to encrypt it .

BANDWIDTH

Wireless networks suffer from low and unreliable bandwidth. This problem is due to the radio media.

Many parameters can affect radio liaison interferences, obstacles, mobility…etc as the number of frequencies is limited, and as the bandwidth is proportional to the frequency, the radio frequency space is cut in channels

Contd…

For Wi-Fi, there are two main frequency spaces, 2.4 GHz (802.11b/g) and 5 GHz (802.11a). 2.4 GHz is also the operating frequency of microwaves, so, using both of these in a close space affects the link quality of the wi fi connection, and sometimes, the link is lost.

Access methods must be designed for avoiding collisions and improve communication but these access methods also reduce the availability of the bandwidth.

Energy

A known problem of radio links is the amount of energy they require, not only for the amount of calculation needed for modulation, but mainly for the power needed for the antenna .

Contd…

ASYMMETRIC CONNECTIONS An asymmetric connection is a common problem in wireless

telecommunications. There are many causes for that. The radio propagation model is the main cause.

This problem can also appear depending on the chipset design. Some

chipsets can restore a low-power signal but will not be able to provide enough power to the antenna for responding to this signal.

INTERFERENCE This is the major problem with mobile ad-hoc networks as links come

and go depending on the transmission characteristics, one transmission might interfere with another one and node might overhear transmissions of other nodes and can corrupt the total transmission.

 

Contd….

DYNAMIC TOPOLOGY This is also the major problem with ad-hoc routing since the topology is

not constant. In ad-hoc networks, routing tables must somehow reflect these changes

in topology and routing algorithms have to be adapted.

ROUTING OVERHEAD

In wireless ad-hoc networks, nodes often change their location within network. So, some stale routes are generated in the routing table which leads to unnecessary routing overhead.

 

Advantages & Disadvantages

The following are the advantages of MANET’S

They provide access to information and services regardless of geographic position.

These networks can be set up at any place and time. These networks work without any pre-existing infrastructure.

Some of the disadvantages of MANET’S are

Limited resources. Limited physical security. Intrinsic mutual trust vulnerable to attacks. Lack of authorization

facilities. Volatile network topology makes it hard to detect malicious nodes.

CONCLUSION

On large and dynamic topologies, reactive protocols will have an advantage,

while on small and relatively fixed topologies; proactive protocols will be

more efficient.

Nevertheless, hybrid protocols have a slight advantage on both approaches,

as they use a proactive protocol for small distances and a reactive protocol for

longer distances.

REFERENCES

http ://www.crhc.uiu c.edu/nhv

http ://www.adhoc.6an ts.net/paul

Computer Networks by Tanenbaum

THANK YOU