chapter 5 ad hoc wireless
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ad hoc wirelessTRANSCRIPT
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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 %&&'
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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%
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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
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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
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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
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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
$roperties
Incre%ental deplo&%ent or partial batch
deplo&%ent can be done 'eplo&%ent or data transfer cost is econo%ical
(ocation ser)ice
*t re+ion with hi+h densit& of nodes,
thro#+hp#t and #ser n#%bers can be enhanced
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Wired Network
;atewa node
3ransmission ran!e
A house with rooftop transcei$er Wired link to the Internet
Wireless link
9i!ure 51*1 Wireless mesh networks operatin! in a residential one
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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
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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$ironmental monitorin!
Differences with the ad hoc wireless networks?
-2oilit of nodes+
-Sie of network+
-Densit of deploment+-
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Hrid Wireless Networks
HWN such as 2ulti-hop cellular networks andinte!rated cellular ad hoc rela networks
- 3he ase station maintains the information aout the
topolo! of the network for efficient routin!
- 3he capacit of a cellular network can e increased if the
network incorporates the properties of multi-hop relain!
alon! with the support of e.istin! fi.ed infrastructure
Ad$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%*
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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&
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,
A
C
DE
,ase Station
Switchin! Center
:
;
atewa
2oile Node
2CN communication
9i!ure 51=1 2CN architecture1
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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
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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
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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
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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
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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
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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
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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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/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