PRASAD ENGINEERING COLLEGE

PAPER ON

MOBILE AD-HOC NETWORK

Presented by

K.ASHWINI 096L1A0404

A.DIVYAJYOTHI 096L1A0405

III YEAR

ELECTRONICS AND COMMUNICATION ENGINEERING

INTRODUCTIONINTRODUCTION

• Mobile wireless networks are popular in 1970sMobile wireless networks are popular in 1970s

• There are currently two variations of mobile wireless There are currently two variations of mobile wireless networknetwork

• Infrastructure network Infrastructure network

• Ad-hoc networkAd-hoc network

Why Ad Hoc Networks ?Why Ad Hoc Networks ?

• Setting up of fixed access points and backbone infrastructure is not always viable

– Infrastructure may not be present in a disaster area or war zone

– Infrastructure may not be practical for short range radios; Bluetooth (range ~ 10m)

• Ad hoc networks:

– Do not need backbone infrastructure support

– Are easy to deploy

– Useful when infrastructure is absent, destroyed or impractical

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What is an Ad hoc Network

• Collection of mobile wireless nodes forming a network without the aid of any infrastructure or centralized administration

• Nodes have limited transmission range• Nodes act as a routers

WHY WE GO FOR MANET?

The wired network is not available and multi-hop wireless networks provide

The only feasible means for communication and information access

Ex: Battlefield communications,disaster recovery etc

MANET: Mobile Ad hoc Networks

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A collection of wireless mobile nodes dynamically forming a network without any existing infrastructure and the relative position dictate communication links (dynamically changing).

From DARPA Website

Battle field communication8

May need to traverse multiple links to reach destination

Mobility causes route changes

Circles shown the coverage area of various laptop computers

Node A wants to transmit packet to Node D,But D is not coverage area of Node A

It sends packet to node D via the Node C

Interference in MANET

• In a wired network, every link may be utilized simultaneously

• On the other hand, neighboring links in an Ad-hoc network interfere with each other

• The interference range is typically much larger than the transmission range.

Implementation of backoff

• It has been observed that the widely used exponential backoff mechanism (e.g., IEEE 802.11)

• is unfair towards nodes in the middle of an Ad-Hoc network with multiple interference domains.

• Hence the unfairness is illustrated and the Impatient Backoff Algorithm is proposed

Routing ProtocolsRouting Protocols Proactive protocols Proactive protocols

– – Traditional distributed shortest path protocolsTraditional distributed shortest path protocols

– – Maintain routes between every host pair at all timesMaintain routes between every host pair at all times

– – Based on periodic updates; High routing overheadBased on periodic updates; High routing overhead

– – Example: DSDV (destination sequenced distance vector)Example: DSDV (destination sequenced distance vector)

Reactive protocolsReactive protocols

– – Determine route if and when neededDetermine route if and when needed

– – Source initiates route discoverySource initiates route discovery

– – Example: DSR (dynamic source routing)Example: DSR (dynamic source routing)

Hybrid protocolsHybrid protocols

– – Adaptive; Combination of proactive and reactiveAdaptive; Combination of proactive and reactive

– – Example : ZRP (zone routing protocol)Example : ZRP (zone routing protocol)

Routing in MANET

• Routing is one of the primary function of MANET

• The development of efficient routing protocols is nontrivial interface etc

• These routing protocol may generally be categorized as two types

» Table-driven» Source-initiated (demand-driven)

Routing in MANETRouting in MANET

Ad-hoc Routing Protocols

Table-driven Source-initiated on-demand

DSDV WRP AODV DSR LMR ABR

CGSRTORA SSR

MANET

Characteristics Dynamic topologies Limited channel bandwidth Variable capacity links Energy-constrained operation Limited physical security

Applications Military battlefield networks Personal Area Networks (PAN) Disaster and rescue operation Peer to peer networks Video gaming

MANET usage areas & limitations

Military scenariosSensor networksRescue operationsStudents on campusFree internet connection sharingConferencesThe coverage area of ad-hoc network is 500

square meter

Variable Bandwidth Disconnected Operation Limited Power

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Power Consumption18

Limited Power Source

Battery Lifetime is limited

Each sensor node plays a dual role of data

originator and data router (data processor)

The malfunctioning of a few nodes consumes

lot of energy (rerouting of packets and

significant topological changes)

Conclusion

Other interesting problems: Applications for MANET Address assignment Qos issues Improving interaction between protocol layers

REFERENCES

http://ieee.ieeexplore.org/ [1]. Rajarshi Gupta, Zhanfeng Jia, “Interference-aware QoS Routing (IQ

Routing) for Ad-Hoc Networks”, published in the proceedings of National conference, held at Jawaharlal Nehru National College of Engineering, Shimoga on 7-8 July 2006

[2]. IEEE Standard for Wireless LAN Medium Access Control (MAC) and Physical layer (PHY) Specifications, Nov. 1997. P802.11

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Any Questions?