Intermittently Connected Mobile Ad Hoc Networks: from Routing to Content Distribution

124 Pages·2011·1.247 MB·English

by  Abbas Jamalipour, Yaozhou Ma (auth.)

SpringerBriefs in Computer Science
Forfurthervolumes:
http://www.springer.com/series/10028

Abbas Jamalipour • Yaozhou Ma
Intermittently Connected
Mobile Ad Hoc Networks
from routing to content distribution
foreword by H. Vincent Poor
Abbas Jamalipour Yaozhou Ma
The University of Sydney The University of Sydney
School of Electrical and School of Electrical and
Information Engineering Information Engineering
Sydney New South Wales Sydney New South Wales
Australia Australia
[e-mail] [e-mail]
ISSN2191-5768 e-ISSN2191-5776
ISBN978-1-4614-1571-8 e-ISBN978-1-4614-1572-5
DOI10.1007/978-1-4614-1572-5
Springer New York Dordrecht Heidelberg London
Library of Congress Control Number: 2011939060
© The Author(s) 2011

All rights reserved. This work may not be translated or copied in whole or in part without the written
permission of the publisher (Springer Science+Business Media, LLC, 233 Spring Street, New York,
NY 10013, USA), except for brief excerpts in connection with reviews or scholarly analysis. Use in
connection with any form of information storage and retrieval, electronic adaptation, computer software,
or by similar or dissimilar methodology now known or hereafter developed is forbidden.
The use in this publication of trade names, trademarks, service marks, and similar terms, even if they
are not identified as such, is not to be taken as an expression of opinion as to whether or not they are
subject to proprietary rights.
Printed on acid-free paper
Springer is part of Springer Science+Business Media (www.springer.com)
toourfamiliesfortheirendlesssupport...

Foreword
Wirelessnetworkingisoneofthemostadvancedandrapidlyadvancingtechnolo-
giesofourtime.Themodernwirelesserahasproducedanarrayoftechnologiesof
tremendous economic and social value and almost ubiquitous market penetration.
Many of these technologies, such as mobile phones and WiFi networks, are based
onso-calledinfrastructurenetworks,inwhichinformationistransferredwirelessly
betweenanend-user’sdeviceandanaccesspointtoabackbonenetworkhavinga
hierarchical control structure to manage information flow in the network. A more
recentlyemergingnetworkstructureisthatofanadhocnetwork,inwhichend-user
terminalscommunicatedirectlywithoneanotherinapeer-to-peerfashionwithout
thebenefitofacontrolstructureprovidedbynetworkinfrastructure.Suchnetworks
areoftenformedinanadhocfashion(hencetheirname)ascommunicatingdevices
appear in somewhat random locations. This type of structure presents new chal-
lengesinsupportingefficientinformationflow,asprotocolstypicallymustrelyon
information forwarding through multiple intermediate devices, each of which acts
autonomously, to deliver messages from source to destination. These challenges
become even greater when the devices are moving, as the network topology then
becomesdynamic.Evenfurtherchallengesariseduetothefactthatcontinuousend-
to-endconnectivitycannotbeguaranteedinsuchnetworks,openinguptheissuesof
what types of information content can be practically transferred through such net-
worksandhowthiscanbestbeaccomplished.Theselatterissuesarethesubjectof
thisexcellentmonograph,whichcollectsforthefirsttimeinbookformtheconsid-
erablerecentresearchdedicatedtothisimportantemergingtopic,muchofitbythe
authorsthemselves.Applicationsinvolvingsuchintermittentlyconnectedmobilead
hocnetworks,orICMANs,arecertaintomultiplyinthecomingyearsasthetech-
nicalsophisticationandgeographicalspreadofend-userdevicesincrease,andthus
thisworkbytwoleadingcontributorstothefieldshouldbeofconsiderableinterest
totheresearchersandengineerslookingtodevelopthenextgenerationsofwireless
networkingtechnologies.
Princeton,NewJersey,August2011 H.VincentPoor
vii

Preface
MobileAdHocNetworks(MANETs)havechangedtheclassicalcentralizedwire-
lessnetworktopologyintoawhole newdomainwithmanypotentialapplications.
WhilemilitaryapplicationsoftheMANEThavebeenunderstoodforsometime,re-
searchoncivilapplicationsoftheMANETshavebecomeoneofthemostimportant
topicsamongtelecomengineersjustinthebeginningofthiscentury.
In general, MANETs are the networks that are formed dynamically by an au-
tonomoussetofmobilenodesconnectedthroughwirelesslinkswithoutrelyingon
anypre-configuredinfrastructureoracentralbasestation.Thesenodesdynamically
create the network connectivity through a temporary network topology, allowing
them to seamlessly communicate with one another in areas with no pre-existing
communicationinfrastructure.Owingtotheself-configurationnatureofMANETs
where connectivity between peer end-terminals can be established automatically
without any pre-configured infrastructure, data transfer is carried out through the
cooperationamongintermediatenodesovermulti-hoproutingpaths.However,one
ofthekeyassumptionsforsucharoutingapproach,namelytheexistenceofanend-
to-end routing path, becomes untenable in cases where the network experiences
intermittentconnectivityduetolimitedtransmissionrange,sporadicnodedensities,
power limitations, and so on. To administer information tracking and data deliv-
erycapabilityinfosteringserviceimprovementintheemergencyresponseandthe
eHealthsector,aswellaspervasivecomputinginruralareas,itisnecessarytode-
velopasupplementaldatadisseminationframeworkbasedonopportunisticdelivery
probability.Infact,ifthedeliverydelaycanbetolerated,thennodemobilitycanbe
exploitedtodeliverselectedmessagestothedestination.Obviously,theseso-called
store-carry-forward (SCF) techniques incur considerable signaling overhead to in-
cludemessagesummariesandmeetingprobabilities,resultinginthedegradationof
networkefficiency.
Based on the above concept, a new subset of MANETs, called Intermittently
Connected Mobile Ad Hoc Networks (ICMANs) could be created. By consider-
ingthenatureofintermittentconnectivityinmostrealworldmobileenvironments
withoutanyrestrictionsplacedonusers’behavior,ICMANsareeventuallyformed
withoutanyassumptionabouttheexistenceofanend-to-endpathbetweenanypair
ix
x Preface
of nodes who are wishing to communicate. It is different from the conventional
MANETs, which have been implicitly viewed as a connected graph with estab-
lishedcompletepathsbetweeneverypairofnodes.FortheconventionalMANETs,
mobilityofnodesisconsideredasachallengeandneedstobehandledproperlyto
enableseamlesscommunicationbetweennodes.However,toovercomeintermittent
connectivityintheICMANscontext,mobilityisrecognizedasacriticalcomponent
fordatacommunicationsbetweenthenodesthatmayneverbepartofthesamecon-
nectedportionofthenetwork.Thiscomesatthecostofadditionalandconsiderable
delayindataforwarding,sincedataareoftenstoredandcarriedbytheintermediate
nodeswaitingforthemobilitytogeneratethenextforwardingopportunitythatcan
probably take the data packet close to the destination. Such incurred large delays
primarilylimitICMANstotheapplications,whichmusttoleratedelaysbeyondtra-
ditionalforwardingdelays.ICMANsbelongtothefamilyofdelaytolerantnetworks
(DTNs).However,theiruniquecharacteristics(e.g.,self-organizing,randommobil-
ityandadhocbasedconnection)derivedfromMANETsdistinguishICMANsfrom
othertypicalDTNssuchasinterplanetarynetwork(IPN)withinfrastructure-based
architecture.
By allowing mobile nodes to connect and disconnect based on their behaviors
and wills, ICMANs enable a number of novel applications to become possible in
thefieldofMANETs.Forexample,thereisagrowingdemandforefficientarchitec-
turesfor deployingopportunisticcontent distributionsystemsoverICMANs.This
isbecausealargenumberofsmarthandhelddeviceswithpowerfulfunctionsenable
mobile users to utilize low cost wireless connectivity such as Bluetooth and IEEE
802.11forsharingandexchangingthemultimediacontentsanytimeanywhere.Note
thatsuchphenomenalgrowthofcontent-richserviceshaspromotedanewkindof
networkingwherethecontentisdeliveredfromitssource(referredtoaspublisher)
towardsinterestedusers(referredtoassubscribers)ratherthantowardspre-specified
destinations. Comparing to the extensive research activities relating to the routing
andforwardingissuesinMANETsandevenDTNs,opportunisticcontentdistribu-
tionbasedonICMANisjustinitsearlystageandhasnotbeenwidelyaddressed.
Thisbookcoverstheresultsofresearchcarriedoutbytheauthorsonthetopicof
ICMAN.Thisbookprovidesanin-depthdiscussiononthelatestresearcheffortsfor
opportunistic content distribution over ICMANs. The discussion begins by intro-
ducingICMANs,DTNs,andthemostnotableforwardingandroutingtechnologies
(e.g., epidemic routing and its variations, cluster-based routings and super-node-
based routings). Chapter 1 also briefly discusses the mobility impact on routing
performance; an important factor used in enabling packet routing in the network.
Chapter 2 explains various forms of opportunistic content distributions over IC-
MANs. It gives details about some proposed optimizing solutions by considering
the mobility characteristics of the nodes. The idea of cooperation is further em-
ployedtoallowtheencounteringnodestoworktogetherforcarryingoutthecoop-
erativedecision-makingstrategieswhenthenetworkresourcesbecomeconstrained.
Apartfromdesigningforwardingstrategiestodeliverthecontentfromitspublisher
to their interested subscribers, content search or content lookup is another funda-
mental problem that determines the architecture and performance of opportunistic