military satellite communications - Johns Hopkins APL Technical

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32 Johns hopkins ApL TechnicAL DigesT, VoLume 27, number 1 (2006) M military satellite communications: space-based communications for the global information grid David A. Fritz, Bharat T. Doshi, Andrew C. Oak, Steven D. Jones, Jack L. Burbank, Harry L. Miller, John D. Oetting, Ryan M. Collins, Lino A. Gonzalez, and Robert A. Nichols ilitary satellite communications (miLsATcom) systems are critical elements in DoD’s vision for a global information grid (gig). modeled after the commercial internet, the gig will provide global connectivity to support a broad range of military user applications. commercial networking technologies, coupled with military-unique radio communications equipment, enable the gig to support the demands of the highly mobile warfighter operating in complex radio environments. miLsATcom is divided into three categories—narrowband, wideband, and protected—matching user require- ments to suitable frequency bands. ApL is active in the development of miLsATcom systems, leveraging more than 20 years of expertise in satellite communications to ensure the global reach of the gig. THE GLOBAL INFORMATION GRID over the last decade, the internet has enabled tre- mendous gains in business productivity via rapid global information sharing, effective collaboration, and com- munications across organizational boundaries. moti- vated by the immense success of the internet in the com- mercial world, the DoD, the intelligence community, and nAsA have collectively embarked on an ambitious effort to migrate their information systems and networks to a common ip backbone, providing infrastructure and application platforms for network-centric operations and warfare. it is worth noting that, despite the intent to leverage commercial technology, the development of the global information grid (gig) will inevitably require the incorporation of military-unique features into the commercial solutions to address information assurance issues such as communications security, transmission security, and the integration of priority and precedence with commercial quality of service. even with a common ip layer for networking, the physical and link-layer technologies will vary signifi- cantly across the network segments that will compose the gig. Depending on geographical location, commu- nications environment, user density, and other factors, each segment of the gig will apply novel solutions to meet the warfighter’s requirements. The miLsATcom systems are excellent examples of diverse physical and link layers, designed to address unique user require- ments. The frequencies at which miLsATcom systems

Transcript of military satellite communications - Johns Hopkins APL Technical

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D. A. FriTZ et  al.

M

militarysatellitecommunications:space-basedcommunicationsfortheglobalinformationgrid

David A. Fritz, Bharat T. Doshi, Andrew C. Oak, Steven D. Jones, Jack L. Burbank, Harry L. Miller, John D. Oetting, Ryan M. Collins, Lino A. Gonzalez, and Robert A. Nichols

ilitarysatellitecommunications(miLsATcom)systemsarecriticalelementsin DoD’s vision for a global information grid (gig). modeled after the commercialinternet,thegigwillprovideglobalconnectivitytosupportabroadrangeofmilitaryuser applications. commercial networking technologies, coupled with military-uniqueradiocommunicationsequipment,enablethegigtosupportthedemandsofthehighlymobilewarfighter operating in complex radio environments.miLsATcom is dividedinto three categories—narrowband, wideband, and protected—matching user require-mentstosuitablefrequencybands.ApLisactiveinthedevelopmentofmiLsATcomsystems,leveragingmorethan20yearsofexpertiseinsatellitecommunicationstoensuretheglobalreachofthegig.

THE GLOBAL INFORMATION GRID over the lastdecade, the internethasenabledtre-

mendousgainsinbusinessproductivityviarapidglobalinformation sharing,effectivecollaboration,andcom-munications across organizational boundaries. moti-vatedbytheimmensesuccessoftheinternetinthecom-mercial world, the DoD, the intelligence community,andnAsAhavecollectivelyembarkedonanambitiousefforttomigratetheirinformationsystemsandnetworkstoacommonipbackbone,providinginfrastructureandapplicationplatformsfornetwork-centricoperationsandwarfare. it is worth noting that, despite the intent toleveragecommercialtechnology,thedevelopmentoftheglobalinformationgrid(gig)will inevitablyrequirethe incorporation of military-unique features into the

commercialsolutionstoaddressinformationassuranceissues such as communications security, transmissionsecurity,andtheintegrationofpriorityandprecedencewithcommercialqualityofservice.

even with a common ip layer for networking, thephysical and link-layer technologies will vary signifi-cantlyacross thenetworksegments thatwillcomposethegig.Dependingongeographicallocation,commu-nicationsenvironment,userdensity,andotherfactors,eachsegmentofthegigwillapplynovelsolutionstomeetthewarfighter’srequirements.ThemiLsATcomsystemsareexcellentexamplesofdiversephysicalandlink layers, designed to address unique user require-ments.ThefrequenciesatwhichmiLsATcomsystems

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operate were chosen to best address a range of userrequirements: narrowband communications at uhF,widebandcommunicationsatshF,andprotectedcom-munications at ehF. each of these frequency bandsprovidesdistinctivecapabilitiesandpresentsnewchal-lengesintermsofintegratingwiththenetwork-centricvisionforthegig.

before2002,themiLsATcomroadmapwasfocusedonacontinuedpresenceinthethreeprimaryfrequencydomains (uhF, shF, ehF), representing three classesofusersandtechnology.TheroadmapdepictedinFig.1 shows that,before2002,modifications to systems inmanycaseswereevolutionary,notrevolutionary.ineachfrequencyband,theroadmapcalledforanewsystemtoreplacecurrentsatellites, incrementallyimprovingper-formancethroughstate-of-the-arttechnologyinsertion.in January 2002, the DoD initiated the Transforma-tionalcommunicationsstudy(Tcs)toconsiderwaystorevolutionizemiLsATcomsystems.oneTcsgoalwastocreateahigh-capacityipbackboneinspace.Asaresult,thepost-2002Tcsroadmapsoughttoconsoli-date functionality across the previously separate wide-band and protected satellite systems and, through theapplicationofadvancedopticaltechnology, toachieve

amiLsATcomarchitecturethatwouldremovecom-municationsasaconstrainttothewarfighter.

WhiletheTcsroadmaphasremainedunchangedsince 2002, the timelines and programmatics to bringthevision to realitycontinue tobe refined.The inte-grated system-of-systems miLsATcom architecturefor the transformation is better illustrated in Fig. 2,which highlights the satellite systems to be deployedoverthenext5to15years.Themobileuserobjectivesystem (muos), Wideband gapfiller system (Wgs),and Advanced ehF (AehF) will be deployed earlier,while the Transformational satellites (TsATs) andtheAdvancedpolarsystem(Aps)willcomeonboardmostlyafter2012.Thelowdataratesofthemuosmakeitsuitableprimarilyfortacticalapplications.Theothersystemscanbeusedfortactical,strategic,andbackboneapplications.Together,thesesystemsrepresentamajorcommitment to miLsATcom and to realizing thegigvision.

Anadditionalchallengeinachievingthisvisionistointerconnectthesesatellitesystemstoground-andair-based tactical networks and to high-capacity wirelinebackbones like the gig bandwidth expansion (gig-be)fiber-opticnetwork.Alargepartofthischallenge

Figure 1.  Transformational Communications Study impact on the DoD MILSATCOM Roadmap. 

Figure 2.  MILSATCOM system of systems (GEO = geosynchronous Earth-orbit satellites).

AEHF(3 GEO)

APS

RF

Laser

GIG-BE/teleport connectivity

TSATs (5 GEO)

MUOS(4 GEO)

WGS(5 GEO; X- and

Ka-band)

Joint Tactical Radio System/ wireless connectivity

. . . . .

IC backbone

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isbeingaddressedbytheDoDTeleportprogram.Thisprogram is aimed at allowing true multiband capabil-itysothatdifferentsatellitesystemsaswellasdifferentground-basedsystemscaninteroperatebyconnectingatoneoftheglobalTeleportsites.Althoughinitialdeploy-ment of Teleport provides only circuit connectivity, afuture generation will have ip capabilities consistentwiththevisionforthegig.

ThefollowingsectionsbrieflydescribethemiLsAT-comsystems,theTeleportprogram,andApL’sinvolve-ment in the integrationof thesenetwork segments tocreatethegig.

NARROWBAND SATCOMDoD’snarrowbandsATcomsystemsyieldlow-data-

rate (less than 64 kbps), beyond-line-of-sight (bLos)communications. These systems have been designedwith the mobile, tactical warfighter in mind. This isapparent in the satellite constellation design and fre-quenciesofoperationaswellasthesystem’ssupportofrelativelysimple,low-cost,mobileterminals.

These narrowband systems are designed to operatein theuhFband(290–320mhzuplinkand240–270mhz downlink). systems operating in this band arebetterabletopenetratefoliageandatmosphericcondi-tionssuchasclouds,rain,orfog.uhFsATcomtermi-nalantennashaverelativelybroadbeamwidths,whichallowsthemobileusertocommunicateevenifterminalantennapointingisimprecise.uhFsATcomispro-videdbygeosynchronoussatellites,enablingworldwidecoverageuptoapproximately±70ºlatitude.Therefore,it can be seen that the uhF sATcom systems weredesigned to enable bLos communications anywhere,anytime.

Although DoD’s uhF sATcom is protected byencryption,itisnotdesignedwithanti-jam,lowprob-abilityofintercept(Lpi),orlowprobabilityofdetection(LpD) capabilities. While one could certainly see theutilityof these features inmanymilitary applications,the absence of this functionality keeps the design ofthese uhF sATcom systems relatively simple. Thishelps keep terminal costs low compared with otherDoD miLsATcom systems and allows DoD to fieldtensofthousandsofuhFsATcomterminalsforthewarfighter.

The UHF Follow-On Systemnarrowband sATcom is currently provided by a

constellationofuhFFollow-on(uFo)satellites.Thefull uFo constellation consists of two active satel-lites ineachof fourglobalcoverage regions.The sub-satellitepointsare locatedover theAmericasand theAtlantic,indian,andpacificoceans.Theconstellationalso consists of spare on-orbit satellites that providebackuporsurgecapabilitywhenneeded.ThefirstuFo

satellitewaslaunchedin1993,andtheconstellationwascompletedwiththelaunchofuFoFlight11inDecem-ber2003.

becausenarrowbandsATcomcansupportawidevarietyofapplications,theuFosystemanditspredeces-sorshavebeenconsistentlyoversubscribed.Tomitigatethis problem, DoD has developed multiple access pro-tocolstoallowasingleuhFsATcomchanneltobesharedbymanyapplications.Theseprotocolsusetime-division multiple-access schemes, with access grantedeither on demand or according to a predeterminedplan. While these protocols do allow wider access touhFsATcomresources,theconsistentandsustainedgrowth in demand for such access since the first gulfWarcontinuestoleavethesystemoversubscribed.

The ongoing development and evolution of theDoD Teleport program (discussed later in this article)will give the uFo user access to the gig and someDefenseinformationservicesnetwork(Disn)services.Althoughaccesswillbe somewhat limited in termsofdynamicaccessesandthenumberofDisnservicespro-vided,thisisanimportantfirststepinbringingthegigtothemobiletacticaluser.

The Mobile User Objective Systemmuosiscurrentlyunderdevelopmentasaneven-

tual replacement for the uFo system. To meet futuremiLsATcom requirements, it has become apparentthat dramatic improvement is needed in some areas,suchascapacityandsupportofcommunicationsonthemove (coTm). While DoD’s narrowband sATcomsystems have always supported mobile platforms, themilitary’s conception of coTm has evolved signifi-cantlyover time. For example, over thepast 30 years,theconceptof“onthemove”hasevolvedfromshipsatsea to includeaircraft, vehicles, single-personportableterminals(tofitinabackpack),andevenmissilessuchasTacticalTomahawk.Theconceptcontinuestoevolveas the military pursues support of communications tohandheldterminals(resemblingverylargecellphones)inthemuosera.supportofthislatterterminaltypewillbringuhFsATcomcapabilitytousersatthe“tipof the spear,” further increasing the demand for uhFcapacity. Also, current and future military operationsmayplacetheseusersinhighlychallengingpropagationenvironments (such as urban terrain and heavy foli-age)thatarenotwellservedbytoday’suhFsATcomsystems.Asaresult,muoswillberequiredtoprovideincreasedcapacity toplatforms that arehighlymobileandareoperatinginthemostchallengingpropagationenvironments.

muos must also be integrated into the gig tofacilitatewarfighteraccesstoDisnservices.ThisaccesswillbeprovidedviatheDoDTeleportandwillbringanew setof capabilities tobear. For example, amuosuser could use Disn services to communicate with a

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non-muosuserortopullpertinentinformationfromappropriatedatabasesonthegig.inthelattercontext,themuosuserwouldbeanalogoustoacellularphoneuserwithinternetaccess,obtainingkeyinformationonanas-neededbasis.

giventhe largeDoDinvestment in terminal infra-structure and the impracticality of an instantaneoustransitionfromtheuFosystemtoanewsystem,muosmust also support backward compatibility with termi-nalsdesignedforoperationwiththeuFosystem.Thisconstraintfurtherexacerbatesthetechnicalchallenges(improved capacity, coTm, gig access) discussedpreviously.

ThenavyservesasexecutiveagentfornarrowbandsATcom, and therefore has responsibility for thedevelopment andprocurementofmuos.muos ini-tialoperationalcapability(ioc)iscurrentlyscheduledfor2010,withfulloperationalcapabilityin2014.Akeytenet of the navy’s strategy for overcoming technicalchallengesistodesignmuosasasystemofintegratedsegments.inpreviousmiLsATcomsystems,thespacesegment (satellites) was typically developed separatelyfromthevariousgroundsegments(whichweretypicallydevelopedseparatelyfromeachother).bydevelopingallmuossegmentsconcurrently, themuosprogramisabletoensureacoherentdesignandoptimizethesys-tem’scost-effectiveness.

Anotherkeytenetinthedevelopmentofmuosistoleverageadvancesincommercialtechnology.Whilenotnecessarilyacommercialsuccess,theconstructionof technically advancedmobile satellite phone servicesystemslikeiridium,Aces,andThurayahasprovideda wealth of advances that muos can leverage. Forexample, the state of the art for large on-orbit anten-nas,linearamplifiers,andmodularspacecraftbuseshasbeen significantly advanced by these commercial sys-tems.Furthermore,theexplosionofthecellularphoneindustryoverthelastdecadehasbeenaccompaniedbysignificantimprovementsinbothterminal(i.e.,phone)technologyandtheabilitytoprovideon-demandaccessto wireless communications services. Leveraging thesetechnologies will result in more efficient resource uti-lization, increased effective capacity, and improvedcoTm.

APL Contributions to UHF SATCOMApLhasprovidedtechnicalsupportfornarrowband

sATcomsincetheveryearlydaysofDoD’sfirstuhFsystem. This support has continued for the uFo andmuos programs, where ApL has served in a trustedagentrole.inthisroleformuos,ApLhasassistedthenavyinthedevelopmentofreferencearchitecturesforconsideration.1,2 The Laboratory has also been deeplyinvolvedintheperformanceassessmentsofmorethan24 proposed architectures for the muos analysis ofalternatives (AoA)andcontinueswith theassessment

ofdetailedarchitecturesunderdevelopmentbyindustryteams.ApLisalsoactivelyinvolvedinthedevelopmentofthemuosperformancespecification,whichistheprincipaltechnicalguidanceforthedevelopmentofthesystem.inaddition,theLaboratorywasrecentlyaskedtouseitsuhFsATcomexpertiseasaprimaryauthoroftheu.s.proposalfortheprovisionofuhFsATcomservicetonATo.Finally,ApLprovidestechnicalsup-port to the uhF sATcom user community. As arecentexample,theLaboratoryhasbeenthetechnicaldirectionagentfromconceptdevelopmenttofieldtest-ingfortheTacticalTomahawkmissileprogram,whichusesuhFsATcomforin-flightcommunicationswithaTomahawkmissile.

manytechnicalchallengeslieaheadasthedetailedmuos design is refined and the system is fielded. byrecalling the navy’s two key tenets for overcomingthese challenges, one sees the technical contributionsrequiredofApLinitstrustedagentrole.onekeytenetofthenavy’sapproachistodesignmuosasasystemofintegratedsegments.ThenavyreliesonApLtounder-stand the technical details of each segment and alsohowthesesegmentsmustbeintegratedtoachievethedesiredperformance.inthislight,ApLisalsorespon-sible for providing independent system performanceassessments of various architectures. The second keytenetofthenavy’sapproachistoleverageleading-edgecommercial technologies. success requires an under-standingnotonlyofthesetechnologiesbutalsoofmili-tary-uniquerequirementsandmethodologies.ThenavyreliesonApLtoprovide thisunderstanding, toassesshow commercial technologies can be applied to meetmilitaryrequirements,andtoidentifysituationswheremodificationstothesetechnologiesareneededordevel-opmentofalternativetechnologiesiscalledfor.

PROTECTED SATCOMDoD’sehFsATcomsystemsofferprotectedbLos

communications for strategic, tactical, and coalition-partner users. These sATcom systems use onboardpartialprocessing,advancedsignalprocessing,andfre-quencyhoppingtoproviderobustcommunicationsthatcanoperateinthepresenceofinterferenceandwithinthemostchallengingenvironmentalconstraints.Thesesystemshavealsobeendesignedtominimizetheprob-abilityofinterceptionanddetection,enablingincreasedcovertness.

The Milstar Program and Advanced EHFThe milstar program began in the 1980s primarily

asastrategicsystemtosupportnuclearcommandandcontrol for u.s. bombers, ballistic missile submarines,fixed-siteandmobilenuclearmissilesystemswithintheunited states, and mobile nonstrategic nuclear forcesineurope.Thefirst-generationehFsATcomsystem,

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milstar-i,achieveditsiocin1994andisdesignedtogiveanti-jamandLpi/LpDprotection superior to thatof other miLsATcom systems. milstar-i providesextremely robust communications for command andcontrol of u.s. strategic forces by using a very largebandwidth (2 ghz uplink and 1 ghz downlink) todeliver up to 92 low-data-rate communications chan-nelsatamaximumdatarateof2400bps.Themilstar-isatellites also implement cross-links between satellitessothatu.s.forcescancommunicatearoundtheworldwithoutrequiringanygroundrelaystations.

AsaresultoftheendofthecoldWarandlessonslearnedfromoperationDesertstorm,themilstarpro-gram was restructured, placing heavier emphasis onsupportoftacticalusers.milstar-iiachieveditsiocin2001andsupportsstrategicandtacticaluserswithdataratesofupto1.544mbps.italsousesadaptiveuplinkbeamforming techniques to mitigate uplink jamming.ThecurrentehFconstellationconsistsoftwomilstar-i satellites and threemilstar-ii satellites, alongwithavariety of other ehF payloads hosted onboard otherDoD satellites. The next-generation ehF sATcom,theAehFprogram,will takeadvantageofnew tech-nology toprovidehigher data rates, up to8mbps, tosupporttherapidlygrowingrequirementsforprotectedcommunications within both strategic and tacticaluser communities. The first AehF satellite is sched-uledtobe launchedin2007,withtwomore launchedat1-year intervals.AdditionalAehFsatellitesmaybeprocured pending decisions on the next generation ofehFsatellites.

Transformational Communications SatellitesThroughtheTcsmentionedearlier, leadersinthe

DoD, intelligencecommunity,andother federalagen-ciesdeterminedthatthecurrentlegacysatellitecommu-nications infrastructure (including AehF) lacked thecapacity, interoperability,control,adaptability, respon-siveness, and coverage to support operations. ThisresultedinthemiLsATcomrestructuringdepictedinFig.1.Aspartofthisrestructuring,theAehFconstel-lationwasreducedfromfivetothreesatellitesandtheWgsconstellationof threesatelliteswas increasedtofive. To address the challenges posed by this restruc-turing, the Transformational communications office(Tco)wasestablishedon3september2002byauthor-ityoftheundersecretaryoftheAirForcetodevelopand coordinate implementation of a Transformationalcommunications Architecture (TcA) to maintainAmerica’sasymmetricinformationanddecisionsuperi-orityandaddresstheneedofreplacingnumerousaginglegacysystems.AsshowninFig.2,thecentralsystemintheTcAistheTsATsystem,whichwillprovideacon-stellationofinteroperablesatellitesthatwillobjectivelyimproveconnectivityanddatatransfercapabilitywhileremoving bandwidth constraints for worldwide u.s.

requirements across DoD, civil, and intelligence com-munity operations. The TsAT system shares manysimilarities with previous ehF systems but supportsother frequency bands including ka-band. The TsATsystem is unique, however, in that TsATs will hostrouting functionality, enabling space-based ip routing.TsATs are envisioned to also provide increased linkdatarates, improvedefficiencythroughdynamicband-widthresourceallocation,andsupportforDoDquality-of-serviceconcepts.inaddition,theyareenvisionedtosupportavehicularcoTmcapability,whichisconsid-eredessentialtosupporttheArmy’sfuturewarfightingconceptsandnext-generationsystemssuchastheFuturecombatsystem.

APL Contributions to Protected SATCOMTheprincipalroleofApLinthedevelopmentofDoD

ehFsATcomhasbeeninsupportofArmyandnavyearth terminal designs, vulnerability assessments, andnetworkmanagement.sincethemid-1980s,theLabora-toryhasworkedfortheArmyprojectmanagersforehFearth terminals at Fort monmouth, new Jersey. Thisworkhas includedadiversesetofactivities suchasthedevelopmentofconceptsfortheuseandremotecontrolofnetworksofArmyehFterminals,3,4contributionstotheconceptsandspecificationsfortheearthterminals,mod-elingandsimulationofnetworkperformance,5introduc-tionofnewtechnologies(suchasturbo-codes) intothesignalprocessingoftheterminals,6,7anddevelopmentofsoftwaretoolsfordecisionmakingandalgorithmstosup-portthemilitarydeploymentoftheterminals.8–11

overthesameperiod,ApLhassupportedthenavy’sehFterminalprogramsbyevaluatingthecriticalaspectofperformanceagainst jammingand intercept threatsfor both surface ships and submarines. This has beendonethroughmodelingandsimulationandbyempiri-caltestingofshipsandsubmarinesatseaoverapproxi-matelyadecade.12ApLhasalsoinfluencedthedesignofthespacesegmentofthemilstarandAehFsystemsinspecificareas,suchassatelliteonboardnullingantennasand resource control algorithms that affect earth ter-minalperformance.recently,theLaboratoryhasbeendetermining the role that sATcom will play in theArmyFutureForce.13TheseApLactivitiesareexpectedtocontinuethroughtheAehFtimeframeandintotheTsATgenerationofehFsATcom.

WIDEBAND SATCOMThewidebandsATcomsegmentof themiLsAT-

com architecture is built around the Defense sat-ellite communications system (Dscs), which hasprovided the bulk of sATcom capacity for the mili-tary for decades. The origin of miLsATcom can betraced back to project score (signal communica-tionbyorbitingrelayequipment), launched in1958.

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Asubsequenteffort,calledtheinitialDefensecommu-nicationsatelliteprogram,wasdevelopedforoperationaluse.itsemploymentduringtheVietnamWarprompteditsnamechange to the initialDefensesatellitecom-municationsystem.

The Defense Satellite Communications Systemcurrent DoD wideband capabilities have evolved

fromthesesimplebeginningstothecurrentgenerationof satellites, Dscs-ii and -iii. The Dscs-ii commu-nicationspayloadhadfourchannelswithvariouscom-binations of bandwidth and antennas. The combina-tions provided the flexibility to handle a wide varietyoflinksandtocommunicatewithterminalsofvarioussizes. initial terminals constructedatmajornodeshad18.3-m-dia.antennas.Thefirst2Dscs-iisatelliteswerelaunchedinnovember1971;byseptember1982,14hadbeenlaunched,4werenotplacedinorbitasaresultoflaunch vehicle failures, and 6 were operational withvaryingdegreesofavailability.

The Dscs-iii is the third-generation general-pur-posemilitarycommunicationssatellite.itevolvedfromaspin-stabilizedsatellitetoathree-axisbody-stabilizedsatellite, offering significantly greater capacity, longerlife,andimprovedresistancetohostileactivitiessuchasjamming. Dscs-iii development started in 1977. Thefirstwas launched in1982,and11additional satelliteshavebeenlaunchedsincethen.TheDscsserviceLifeenhancementprogramensurescontinual,robustwide-bandcommunicationsformanyyearstocome.

As capacity requirements ballooned in the 1990s,theDscswasaugmentedthroughtheleasingofcom-mercial transponders. in current military operations,thesetransponderssupport80%oftheDoDsATcomrequirements.

The Wideband Gapfiller SysteminanticipationoftheendoflifefortheDscscon-

stellation, DoD initiated Wgs acquisition to providethree high-capacity satellites that leveraged availablecommercialtechnology.eachoftheWgssatelliteswillsupport2.3gbpsofthroughput,morethanthecapac-ityoftheentireDscsconstellation.basedoncommer-cialsatellitedesigns,theWgssupportsthetraditionalDscsfrequenciesatX-bandandaddsthecapabilityforcommunications at higher ka-band frequencies (30.5ghzuplink,20.0ghzdownlink).Theadditionofka-bandincreasestheavailablespectrumfrom500.0mhzto1.5ghz.

ThekeytotheflexibilityoftheWgsisthedigitalchannelizer(adigitalsignalprocessor),whichdividesthecommunicationscapacityinto1872subchannelsof2.6mhzeachandswitchesandroutes these subchannels.The channelizer can also provide receive-to-transmitcommunicationsbandwidthsofmultiplesof2.6mhzup

toamaximumof125.0mhz.ithastheabilitytomergemultipleuplinksignalsintoasingledownlinkbandortomulticasta singleuplink signalbyconnecting it tomultipledownlinks.italsoallowsgroundmonitoringofthespectrumofanyuplinksignal.

ThefirstWgsisscheduledforlaunchin2007.origi-nally,theWgswasintendedtobridgethegapbetweentheendoftheDscsandthebeginningofafuturesystemto be called the Advanced Wideband system (AWs).however, during the Tcs and subsequent sATcomarchitectureanalysisbytheTco,fundingfortheAWswasusedtoenhancefundingfortheTsATsystem.Tooffset the loss of the AWs, the decision was made tolaunchthreeadditionalWgssatellitestoextendthelifeof the wideband constellation until the TsAT systemcould pick up the wideband requirements in additionto the protected requirements. What was originally athree-ballgapfillerhassincebecomeafullconstellationthat will provide a dramatic capacity increase to thewarfighteroverthenext10years.

Commercial IP Modem SystemsThepresenceoflow-costcoTsmodemsthatsupport

ip-basedtrafficonademand-assignedbasisisprofoundlyaffectingthefutureofthetranspondedmiLsATcomsystems.ThesecommercialmodemsprovidetheabilitytomoreeffectivelysharethelimitedsATcomresourcesamongacommunityofuserswithinthesatellitecover-agearea.

Withthehighcostofcommercialtransponderleas-ing, current military operations are already migratingto these commercial modems to improve operationalefficiency. The Defense information systems Agency(DisA) is leading an effort to identify a standard ipmodemtoensureDoDuserinteroperability.ADisA-ledworkinggrouphasidentifiedtheopenstandardfordigi-talvideobroadcast/returnchannelsatellite(DVb/rcs)asthepreferredsolution.originallybuiltforvideodistri-butionbysatellite,theadditionofrcstoDVbcreatesalow-costuserterminalthatcansupportinternet-accesstypes of services in a hub-spoke architecture. Futuremilitaryoperationswillalsorequirefull-meshconnec-tivity among user terminals, and multiple options arebeingconsideredforaDoDstandard.AstheDVb/rcsisnotwellsuitedtothedemandsofthehighlymobilewarfighter,theArmyisexpectedtoseparatelyprocureanipmodemthatmeetstheirtacticalrequirements.

APL Contributions in Wideband SATCOM For over a decade, ApL has been at the forefront

of the control system architecture for wideband miL-sATcom.eachofthemiLsATcomsystemsrequiresa sophisticated planning and management capability.Forthetranspondedwidebandsatellites,therearefivewidebandsatelliteoperationscenters(Wsocs)around

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theglobe,whichareresponsibleforplanning,configu-ration of the satellite, control of terminal power, andspectrummonitoring.Thesefunctionsensurethatthesatellitesareoperatedefficientlyandthatusersarenotadverselyimpactingoneanother.

since1992,insupportoftheu.s.Armyprojectman-agerforDefensecommunicationsandArmyTransmis-sionsystemsatFortmonmouth,newJersey,ApLhasdeveloped the objective Dscs operational controlsystem(oDocs)architecturefortheDscs(andsoontheWgs)andhasbeenprovidingtechnicaldirectionovertheintegrationofcontrolsystemsintotheoDocsarchitectureattheWsocs.inadditiontodevelopingthearchitecture,ApLdevelopedthesoftwarefunctionsthattieallcontrolsubsystemstogether.

A key element in the oDocs architecture is theDscsintegratedmanagementsystem(Dims),whichprovidesa singleconsole fromwhichallother subsys-tems can be monitored and controlled. in addition,DimsactsastheinterfacetolegacysystemsthatcannototherwisebeintegratedintotheoDocs.underlyingDimsarethesoftwareserviceswithwhichnewsubsys-temsmustcomplytooperateintheWsocs.

Leveraging an extensive background in widebandcontrol,ApLisworkingwiththewidebandcommunityto develop a network-centric management approachfor transformational transponded miLsATcom14 tobetter support the vision of the Tco. This forward-lookingconceptfor2015widebandsATcomisshowninFig.3.Asthegigmovestowardanetworkserviceprovider paradigm, it is a logical progression to vieweachconstituentnetworkasaserviceprovider.

in Fig. 3, the Wgs is shown in this light, provid-ingpeering and transport agreementswithneighboringnetworks including, for example, gig-be and TsAT.

user access services are also provided to both tacti-cal and strategic user communities. With the high-capacityWgssatellitesandtheefficient,net-centricipmodems,thetranspondedmiLsATcomsegmentrep-resentsapowerfulelementinthedeliveryofnetwork-centric enterprise services (nces) to the warfighter.key elements needed to achieve this vision includeenhancementsattheplanningandoperationscenters,aswellasatTeleportsites,toenabletheuserstoestablishipnetworkservices,basedonaservice-levelagreement,for both in-theater communications and interconnec-tionwiththeDoDterrestrialinfrastructure.

THE TELEPORT PROGRAM

ConnectivityTheDoDTeleportprogram,managedbyDisA,pro-

videssatelliteconnectivitybetweendeployedwarfight-ersandtheDisn,asshowninFig.4.priortotheTele-portprogram,theonlymeansofachievingconnectivitywas through the heavily used X-band Dscs satellitesusing1ofthe15standardtacticalentrypoint(sTep)gatewaysites.TheprogramisupgradingselectedsTepsites with additional satellite terminals and basebandequipment. upgrades encompassing three generationsarebeingphasedin.

inthefirstgeneration,whichbeganinApril2002andisnearingcompletion,theTeleportprogramisupgrad-ing7ofthe15sTepsitestoprovideaccessviacommer-cial satellite bands (c- and ku-band). uhF terminalsarecurrentlybeingdeployed,andehFterminalswillbeaddedduringthenextfiscalyear.ingeneration2,whichstarted in 2004 and will end in 2007, ka-band WgscapabilitywillbeaddedtoTeleport sites.Duringgen-

Figure 3.  A  2015  wideband  SATCOM  framework  (MET  =  modernization  enterprise  terminal).

eration 3, which concludes in2012,Teleport siteswill be furtherupgraded to provide access to thenext generation of military satel-lites,includingAehF,muos,andTsATs.

recently, the Teleport programofficewasdirectedbytheofficeofthesecretaryofDefensetotransitionfrom its current circuit-based, timedivision multiplexer approach to anetwork-centric ip-basedcapability.Towardthisobjective,aprototypeipcapabilitywillbeimplementedattwoTeleportsitesbytheendofFY2005.Duringgeneration2,theipcapabil-itywillbeupgradedanddeployedtoallsixcoresites.Thisapproachwillenablemoreefficientuseofsatellitesandwill eliminate thecomplexitiesassociated with the great number

TSATs

WGStacticalusers

GIG-BE

GIG-BE interface to DISN services and NCES

MUOS

X-band Ka-

band EHF

WGS

METMET

MET

METMET

infrastructure sites

MET

Fixed-site access networks

MET

TCgateway MUOS

gateways

Transformationalcommunications (TC)

tactical users MET

MET

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JohnshopkinsApLTechnicALDigesT,VoLume27,number1(2006) 39

spAce-bAseDcommunicATionsForThegig

of service-uniquemultiplexers andbasebandequipmentcurrentlyinuse.

APL Contributions to the Teleport ProgramApLhasbeeninvolvedintheTeleportprogramfrom

its inception. in 2000, staff members played a leadingrole in conducting the navy’s AoA, which led to theimplementationoftheprogramasitexiststoday.15TheAoAreportconsideredtheexistingglobalsiteswiththerequisite equipment and studied issues including Tele-portsiteoptimizationthroughmiLsATcomandcom-mercial sATcom coverage analysis, traffic capacityassessment,protocolanalyses, subsystemspecifications,and overall hardware architecture approaches. Duringthisperiod,ApLsupportedDisAinlayingthefunda-mentalgroundworkfortheTeleportprogram.

in April 2002, the program received governmentapproval and theTeleportprogramofficewas formedwithinDisA.ApLservedasthesystemsintegratorforTeleportandhasplayedakeyroleinsystemsengineer-ing,integration/implementation,andtesting.TheLabo-ratoryworkedwiththeJointstaffonrequirementsdefi-nitionandwiththeArmyonoverallbasebanddesign,was a key contributor to asynchronous transfer modebasebanddesignandtesting,ledtheintegrationofTele-portwithDisnservices,andhadasignificantroleintheearly implementation of uhF sATcom capabilities16andthemonitoringandcontrolsubsystemdesigns.ApLstaffmembershaveconductednumerousstudies,includ-ing geographic coverage, system capacity, and systemavailabilityanalyses,andparticipated inplanningandconducting developmental and operational tests andevaluations as well as operational demonstrations. inaddition, the Laboratory was assigned as the integra-tionandimplementationleadineachofthetheatersto

workwiththeirgovernmentcoun-terparts to coordinate site imple-mentation activities. Finally, ApLperformedriskanalysisandmitiga-tion activities and provided train-ingtoTeleportsiteoperationsstaffand operational support for war-fightermissionsusingnewTeleportcapabilities.

more recently, ApL has beencoordinating and conducting theinitialtestingofipequipment(e.g.,the 2004 Joint user interoperabil-ity communications experiment)developingtherequirements for ipcapability, and designing the pro-totype router suites that were firstdeployedin2004.17,18Figure 4.  DoD Teleport functionality.

CONCLUSIONmiLsATcomwill continue toplayacritical role

in military communications architecture because itcanprovidevoice,video,anddatacommunicationstousersglobally.Aswarfightingapplicationsevolve,miL-sATcommustintegrateandadaptnewtechnologiestosupporttheseapplications.ApLhasbeeninvolvedin the development of these systems from both theconceptual and the deeply technical perspectives fordecades. it isenvisionedthatthiscritical role for theLaboratorywillcontinueinsupportofthenation’smil-itarycapabilities.

reFerences 1russo, A. A., “multi-beam geo satellite concept for the mobile

userobjectivesystem,”inIEEE MILCOM Conf. Proc.(1999). 2Lee, s. c., nichols, r. A., Yuan, r. L., blackert, W. J., and blair,

m. p., “A Leo satellite concept for the Advanced narrowbandsystem,”inIEEE MILCOM Conf. Proc.(1999).

3Tracey, m. s., Army EHF SATCOM Terminal Control, Fs-94-062,Jhu/ApL,Laurel,mD(sep1994).

4Tracey, m. s., Army Control Architecture, Fs-94-062, Jhu/ApL,Laurel,mD(may1994).

5Fritz,D.A.,moy,D.W.,andnichols,r.A.,“modelingandsimula-tionofAdvancedehFefficiencyenhancements,”inIEEE MILCOM Conf. Proc.(1999).

6Jordan,m.A.,andnichols,r.A.,“Theeffectsofchannelcharac-teristicsonTurbocodeperformance,”inIEEE MILCOM Conf. Proc.(1996).

7Jordan,m.A.,“Turbocodeperformanceinpartial-bandJamming,”inIEEE MILCOM Conf. Proc.(1998).

8huffman,J.A.,Network Operational Management and Planning System Functional Architecture Description,Fs-92-124,Jhu/ApL,Laurel,mD(Aug1992).

9Tracey,m.s.,Akhras,h.W.,nichols,r.A.,andJones,s.D.,“con-trolofanArmysmArT-Tbyanexternalcontrolentity,”inIEEE MILCOM Conf. Proc.(1994).

10nichols,r.A.,andconklin,r.e.Jr.,“uplinkpackingofArmymil-starservices,”inIEEE MILCOM Conf. Proc.(1998).

11nichols, r. A., moy, D. W., and pattay, r. s., “A Fast Algorithmfor optimal satellite spot beam pointing,” IEEE Trans. AES (Jul1996).

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40 JohnshopkinsApLTechnicALDigesT,VoLume27,number1(2006)

D. A. FriTZ et  al.

harryL.miller

JackL.burbank

stevenD.Jones

THE AUTHORS

12burbank,J.L.,andJones,s.D.,“ehFmiLsATcomLpi/LpDperformance:performanceinpracticeandmethodsofoptimization,”inIEEE MILCOM Conf. Proc.(2003).

13burbank,J.L.,etal.,Concepts for the Employment of Satellite Communications in the Army Objective Force,Vs-02-106,Jhu/ApL,Laurel,mD(sep2002).

14Fritz,D.A.,andparikh,b.,“networkcentricoperationsoverTranspondedsATcom,” inIEEE MILCOM Conf. Proc.(2004).

15DoD Teleport Architecture Feasibility Study,Vs-00-054,Jhu/ApL,Laurel,mD(Jun2000).16parikh,g.,pitts,c.,Fritz,T.,Leonard,W.,andcriddle,J.,“uhFsATcomimplementation

WithinTeleport,”inIEEE MILCOM Conf. Proc.(2003).17oetting, J. D., “The impact of ipsec on DoD Teleport Throughput efficiency,” in IEEE

MILCOM Conf. Proc.(2004).18Leonard,W.,pitts,c.,andchimento,p.,“Designinganet-centricDoDTeleport,”inIEEE

MILCOM Conf. Proc.(2004).

JohnD.oetting

Andrewc.oak

bharatT.Doshi

DavidA.Fritz

Thesystemsengineeringworkdescribedinthisarticleisconductedinthecommunicationssystemsandnetworkengineer-inggroup(Vic)ofApL’sAppliedinformationsciences(AisD).David A. Fritz(nolongeratApL)wasthesupervisoroftheWidebandsATcomsystemssectioninVicandledateamofengineersatApL’snewJerseyofficeinsupportofArmy

communicationsprogramsatFortmonmouth.Bharat T. Doshi(nowDirectoroftheresearchandTechnologyDevelopmentcenter) ledthe initiatives indevelopingtheglobalinformationgrid(gig),ofwhichthesesATcomsystemsareacriticalpart.Andrew C. OakisthesupervisoroftheLargescalesystemsDevelopmentsectioninVicandanauthorityonuhFmiLsATcom.Steven D. Jones, supervisor of the Theory and Analysis section in Vic, and Jack L. Burbank, chiefengineerofVic,havemade significantcontributions toArmymiLsATcomandvulnerability

assessmentsofehFsATcomforthenavy.Harry L. Millerprovidessecu-ritysystemsengineeringsupporttotheArmysatelliteterminaldeveloperatFortmonmouth.ApL’sTeleportworkisbeingconductedbyDr. John D. OettingandRyan M. Collins(notpictured)underthesponsorshipofDisA.Lino A. Gonzalezprovideson-sitesupporttothesameArmyorganizationoutofApL’snewJerseyoffice.Robert A. NicholsisthegroupsupervisorofVic.Theauthorscanbecontactedthroughrobertnichols.hise-mailaddressisrobert.nichols@jhuapl.edu.

LinoA.gonzalez

robertA.nichols