chapter 5 ad hoc wireless

7/17/2019 Chapter 5 Ad Hoc Wireless

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Department of CSE Confidential

Chapter 5Chapter 5

Ad Hoc Wireless NetworksAd Hoc Wireless Networks


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Introduction

Ad Hoc Network is a multi-hop relain! network

A"#HA net de$eloped in %&'(

Ethernet de$eloped in %&)(

In %&&*+ ,luetooth proposed Ericsson to de$eloped a Short-ran!e+ low-

power+low-comple.it and ine.pensi$e /adio interface

W"AN )(01%% spec1 is proposed in %&&'

0


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Cellular and Ad Hoc Wireless Networks

Cellular Wireless Networks:Infrastructure dependent

network

Ad Hoc Networks:2ulti-hop radio relain! and withoutsupport of infrastructure

- Wireless 2esh Networks

- Wireless Sensor Networks

3he ma4or differences etween cellular networks and ad hoc

networks as summaried in 3ale 51%

6


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Wireless 2esh

Networks

Cellular Wireless Networks Hrid Wireless

Networks

Wireless SensorNetworks

Infrastructure Dependent Ad Hoc Wireless Networks

7Sin!le-Hop Wireless Networks8 72ulti-Hop Wireless Networks8

9i!ure 51%1 Cellular and ad hoc wireless networks1

*


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,

A

C

E

Switchin! Center

:

;atewa

,ase Station

D

2oile Node


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,

AC

9

E

2oile Node

D

Wireless "ink


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Table 5.1 Diferences between cellular networks and ad hocwireless networks

Cellular Networks Ad Hoc Wireless Networks

Fixed inrastructurebased !nrastructureless

"in#leho$ wireless links %ultiho$ wireless links

&uaranteed bandwidth "hared radio channel

'desi#ned or (oice tra)c* '+ore suitable or bestefort data tra)c*

Centrali,ed routin# Distributed routin#

Circuitswitched -acketswitched

"ea+less connecti(it Fre/uenc $ath break 'low call dro$s durin# handofs* due to +obilit

Hi#h cost and ti+e o de$lo+ent 0uick and costefecti(e de$lo+ent

euse o re/uenc s$ectru+ throu#hDna+ic re/uenc reuse based on carrier#eo#ra$hical channel reuse"D%A

sense +echanis+

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2asier to achie(e ti+e snchroni,ation Ti+e snchroni,ation is di)cult andconsu+es bandwidth

2asier to e+$lo bandwidth reser(ation3andwidth reser(ation re/uires co+$lex

+ediu+ access control $rotocols

A$$lication do+ains include +ainl ci(ilianA$$lication do+ains include battle4eldsand co++ercial sector e+er#enc search and rescue o$eration and

collaborati(e co+$utin#

Hi#h cost o network +aintenance "elor#ani,ation and +aintenance $ro$erties

'backu$ $ower source sta)n# etc.*are built into the network

%obile hosts are o relati(el low co+$lexit %obile hosts re/uire +ore intelli#

'should ha(e a transcei(er as well asroutin#6switchin# ca$acit*

%a7or #oals o routin# and call ad+ission are %an ai+ o routin# is to 4nd $athsto +axi+i,e the call acce$tance ratio and+ini+u+ o(erhead and also /uick+ini+i,e the call dro$ ratio recon4#uration o broken $aths

Widel de$loed and currentl in the third"e(eral issues are to be addressed or#eneration successul co++ercial de$lo+ent e(en

thou#h wides$read use exists in deense

)

Table 5.1 Diferences between cellular networks and ad hocwireless networks



pplications of Ad Hoc Wireless Networks

2ilitar Applications

- Estalishin! communication amon! a !roup of soldiers for tactical operations-Coordination of militar o4ect mo$in! at hi!h speeds such as fleets of

airplanes or ships-/e>uirements? reliailit+ efficienc+ secure communication+ and multicastin!

routin!+

Collaorati$e and Distriuted Computin!- Conference+ distriuted files sharin!

Emer!enc #perations

- Search+ rescue+ crowd control+ and commando operations

- Support real-time and fault-tolerant communication paths

&



Wireless 2esh Networks

An alternate communication infrastructure for

moile or fi.ed nodes@users

uick and low cost of deploment+

enhanced ser$ices+ hi!h scalailit+ ease.tendailit+ hi!h a$ailailit+ and low cost per it

%(



Wireless %esh Networks8

Wireless Mesh Networks

operate at license-free ISM bands 2.4GHz ~ GHz data rate of 2Mps to !"Mbps can be s#pported

$roperties

Incre%ental deplo&%ent or partial batch

deplo&%ent can be done 'eplo&%ent or data transfer cost is econo%ical

(ocation ser)ice

*t re+ion with hi+h densit& of nodes,

thro#+hp#t and #ser n#%bers can be enhanced



Wired Network

;atewa node

3ransmission ran!e

A house with rooftop transcei$er Wired link to the Internet

Wireless link

9i!ure 51*1 Wireless mesh networks operatin! in a residential one

%%



Internet

/adio rela node

2ulti-hop radio rela link

Wired link to the Internet

"amp

Co$era!e area

9i!ure 515 Wireless mesh network co$erin! a hi!hwa

%0



Wireless Sensor Networks

A collection of a lar!e numer of sensor nodes that are

deploed in a particular re!ion

Applications?

- militar+ health care+ home securit+ and

en$ironmental monitorin!

Differences with the ad hoc wireless networks?

-2oilit of nodes+

-Sie of network+

-Densit of deploment+-



Hrid Wireless Networks

HWN such as 2ulti-hop cellular networks andinte!rated cellular ad hoc rela networks

- 3he ase station maintains the information aout the

topolo! of the network for efficient routin!

- 3he capacit of a cellular network can e increased if the

network incorporates the properties of multi-hop relain!

alon! with the support of e.istin! fi.ed infrastructure

Ad$anta!es?

- Hi!her capacit than cellular networks due to etter

channel reuse

- Increased fle.iilit and reliailit in routin!

- ,etter co$era!e and connecti$it in holes%*



H&brid Wireless Networks

M#lti-hop cell#lar networks MNs/, inte+ratedcell#lar ad hoc rela& i*0/ networks

1he capacit& of a cell#lar network can be increased ifthe network incorporates the properties of %#lti-hoprela&in+ alon+ with the s#pport of eistin+ 3ed

infrastr#ct#re

Maor ad)anta+es

Hi+h capacit& d#e to increasin+ power ran+e b& cooperationwith %obile nodes

5leibilit&. We can 3nd best s#itable nodes for ro#tin+

0eliabilit&. When one 6S fail, we can link to another 6S

thro#+h %#lti-hop

6etter co)era+e and connecti)it&



,

A

C

DE

,ase Station

Switchin! Center

:

;

atewa

2oile Node

2CN communication

9i!ure 51=1 2CN architecture1

%5



Issues in Ad Hoc Wireless Networks

Issues that effect design, deployment and performance of

ad hoc wireless system are

%1 2edium access scheme

01 /outin!+

61 2ulticastin!+

*1 3ransport laer protocol

51



Medium Access Scheme

Distriuted operation

- full distriuted in$ol$in! minimum control o$erhead

Snchroniation- 2andator for 3D2A-ased sstems

Hidden terminals- Can si!nificantl reduce the throu!hput of a 2AC protocol

E.posed terminals

-3o impro$e the efficienc of the 2AC protocol+ the e.posed nodes

should e allowed to transmit in a controlled fashion without causin!collision to the on-!oin! data transfer

Access dela Should e minimied 2AC1%'

2AC in Ad Hoc networks is responsile distriuted aritration for shared

channel for transmission of packets



he Ma!or Issues of MAC Scheme

%)

3hrou!hput and access dela

- 3o minimie the occurrence of collision+ ma.imie channel utiliation+ and

minimie control o$erhead

9airness

- E>ual share or wei!hted share of the andwidth to all competin! nodes

either on node ased or flow ased.

/eal-time traffic support re>uires e.plicit support1

/esource reser$ation

- Such as ,W+ uffer space+ and processin! power

Capailit for power control

Adapti$e rate control

se of directional antennas

Ailit to measure resource a$ailailit



he Ma!or Challenge of "outing #rotocol

Mo$ilityresult in fre>uent path reak+ packet collision+ and difficult in resource

reser$ation

%andwidth constraint:,W is shared e$er node

&rror'prone and shared channel:hi!h it error rate

(ocation'dependent contention: distriutin! the network load uniforml

across the network

)ther resource constraint:computin! power+ atter power+ and uffer

stora!e%&

"esponsi$ilities of routing protocol: &.chan!in! routin! info+ findin!

path to destination ased on criteria+ lifetime if w@l link+ findin! path reaks+utiliin! minimum andwidth1


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he Ma!or "e*uirement of "outing #rotocol

2inimum route ac>uisition dela Buick route reconfi!uration? to handle path reaks

"oop-free routin!

Distriuted routin! approach

2inimum control o$erhead

Scalailit


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he Ma!or Issues in Multicast "outing #rotocols

/oustness

- reco$er and reconfi!ure >uickl from link reaks

Efficienc

-minimum numer of transmissions to deli$er a data packet to all the

!roup memers1

2inimal Control o$erhead

BoS support

Efficient !roup mana!ement

Scalailit

Securit

0%


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ransport (ayer #rotocols

)$!ecti+es: Settin! up and maintainin! end-to-end connections+

/eliale end-to-end data deli$er+

9low control and

Con!estion control

Ma!or performance degradation:

9re>uent path reaks+

uent network partitions

00


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#ricing Scheme

Intermediate nodes willin!ness to rela packets


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-uality of Ser+ice #ro+isioning

BoS often re>uires ne!otiation etween the host and

the network+ resource reser$ation schemes+ prioritschedulin! and call admission control

BoS in Ad hoc wireless networks can e on a per flow+

per link+ or per node asis1

-os #arameters

Different applications ha$e different re>uirements

2ultimedia? andwidth and dela are the ke parameters

2ilitar? ,W+ dela+ securit and reliailit

Emer!enc search -and-rescue? a$ailailit is the keparameters+ multiple link dis4oint paths

WSN? atter life+ minimum ener! consumption

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-uality of Ser+ice #ro+isioning

-oS'aware routing:

- 3o ha$e the routin! use BoS parameters for findin! a path

-3he parameters are network throu!h put+ packet deli$er ratio+ reliailit+

dela+ dela 4itter+ packet lost rate+ it error rate+ and path loss

-oS framework:-A frame work for BoS is a complete sstem that attempts to pro$ide the

promised ser$ice

-3he BoS modules such as routin! protocol+ si!nallin! protocol+ and

resource mana!ement should react promptl accordin! to chan!es in the

network state

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Self')rgani.ation

An important propert that an ad hoc wireless network should e.hiit is

or!aniin! and maintainin! the network itself

2a4or acti$ities? nei!hour disco$er+ topolo! or!aniation+ and topolo!

reor!aniation

Ad hoc wireless networks should e ale to perform self-or!aniation

>uickl and efficientl

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Security

3he attack a!ainst ad hoc wireless networks are classified into two tpes?


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Ma!or Security hreats

/enial of ser+ice:either consume the network ,W or o$erloadin!

the sstem

"esource consumption

- Ener! depletion? directin! unnecessar traffic throu!h nodes

,uffer o$erflow? fillin! unwanted data+ routin! tale attack

7fillin! none.istent destinations8

Host impersonation:A compromised node can act as another node and

respond control packets to create wron! route entries and terminate the

traffic

Information disclosure Interference: , creatin! wide-spectrum noise

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Add i d S i /i


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Addressing and Ser+ice /isco+ery

An address that is !loall uni>ue is re>uired for a node to participate in

communication

- Auto-confi!uration of address is re>uired to allocate non- duplicate

addresses to the nodes

-In networks fre>uent partitionin! and mer!in! of network components

re>uire duplicate address detection mechanisms

Nodes in the network should e ale to locate ser$ices that other nodes

pro$ide1

0)

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&nergy Management

ransmission power management:

- /9 hardware desi!n ensure minimum power consumption

- ses $ariale power 2AC protocol

- "oad alance in network laer

- /educin! the numer of retransmissions at the transport laer

- Application software de$eloped for moile computers

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&nergy Management 0000

%attery &nergy Management:e.tendin! the atter life takin! chemical

properties+ dischar!e patterns+ and the selection of a atter from a set ofatteries that is a$ailale for redundanc1

#rocessor #ower Management:C


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Scala$ility

3he latenc of path-findin! in$ol$ed with an on-demand routin! protocol in a lar!e

ad hoc wireless network ma e unacceptal hi!h1

A hierarchical topolo!-ased sstem and addressin! ma e more suitale for

lar!e ad hoc wireless networks

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/ l t C id ti


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/eployment Considerations

3he deploment of a commercial ad hoc wireless network has

the followin! enefits?

- "ow cost of deploment

- Incremental deploment

- Short deploment time

- /e-confi!urailit

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Ma!or Issues for /eployment

Scenario of deployment

- 2ilitar deploment

Data-centric 7e1!1 WSN8

ser-centric 7soldiers or $ehicles carrin!

wireless communication de$ices8

- Emer!enc operations deploment- Commercial wide-area deploment

- Home network deploment

"e*uired longe+ity of network:/e!enerati$e power source can

e deploed when the connecti$it is re>uired for a lon!er

duration of time

Area of co+erage66

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Ma!or Issues for /eployment

Ser+ice a+aila$ility: /edundant nodes can e deploed to a!ainst

nodes failure1

)perational integration with other infrastructure:

Can e considered for impro$in! the performance or

!atherin! additional information+ or for pro$idin! etter BoS

Choice of protocols: 3he choices of protocols at different laers of the

protocol stack is to e done takin! into

consideration the deploment scenario1

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Ad Hoc Wireless in Internet


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Ad Hoc Wireless in Internet

Similar to wireless internet+ the ad hoc wireless internet e.tends the

ser$ice of the Internet to the end user o$er an ad hoc wireless network 1Ma!or issues to $e considered:

1ateways:Entr points to the wired Internet

Address Mo$ility:Similar to the 2oile I

chapter 5 ad hoc wireless

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