IPoverSatellite
Ennes Workshop | October 5 2012
inBroadcastCommunicationsEnnes Workshop|October5,2012
Purpose
Providebroadcastengineerswithinsightintothebenefits,issues,andchallengesassociatedwithusingInternetProtocol(IP)oversatellite
Thisdiscussionwillcover:
Briefhistoryofspacecommunications
Introductiontosatellitecommunicationstheory IntroductiontoIPA li ti
f t llit IP t b d ti ApplicationofsatelliteIPtobroadcasting
BriefHistoryofSpaceCommunications
GaleCraterMars
GeosynchronousEarthOrbit
Never Placed inNon-Equatorial Orbit
Orbital Plane Clark Belt
Equator
22,240 miles (35,790 km)Degrees of Longitude
2o SpacingStation Keeping2 Spacing
916 miles (1,475 km)
164,870 miles265,490 km
6 870 mph
Orbital Circumference:
Orbital Velocity:
Keeping
Geosynchronous orbit @ 0o Latitude, directly over the
EquatorTherefore, orbital position is reported in degrees of
LongitudeTypical orbital period = Earth rotation 23hr 56min
4sec6,870 mph
11,060 kphOrbital Velocity: Typical orbital period = Earth
rotation, 23hr 56min 4sec
Satellite orbits in a figure-eight when viewed from the
ground
SatelliteSpectrum
30
Ka Band18.2 - 30 GHz
Ku Band10.7-14.5 GHz
C-Band3.6 -7.125 GHz
Satellite
1
Satellite MajorCommunicationsComponents
Antenna:Receivescompositespectrumacrossentireuplink
Amplifier:Receiveside
Transponders:Typicallymany,withvariedconfigurations
FrequencyConverter:Mixer(pertransponder)
Amplifier:Transmitsidep
Antenna:Transmitsdownlinktoreceivingearthstation
TransponderBlockDiagram
RX Antenna (Uplink)14.0-14.5 GHz (F1)
TX Antenna (Downlink)11.7- 12.2 GHz (F1-F2)
Tx Band Pass
Filter (OMUX)
MixerOutput Switching
and Isolation
Rx Band Pass
Filter
Transponder
Low NoiseAmplifier
(LNA)
High PowerAmplifier
(HPA)Local Oscillator (L/O) 2300 MHz (F2)
Input, or Receive Band Pass Filter Low Noise Amplifier (LNA)
acts as a low power pre-amplifier Mixer, or Frequency Down
Converter
- Includes Local Oscillator, or L/O Output filter (OMUX) High
Power Traveling Wave Tube Amplifier (HPA or TWTA) Output isolation
and switching
SignalPolarization
SignalPolarizationisapropertyofelectromagneticwaves
Threedimensionsofelectromagneticwaves
Frequency,amplitude,andphaseq y, p , p
Asimpleplanewaveistwodimensional
Theplaneisperpendiculartothedirectionthewavepropagates
Theelectricvectorcanbedecomposedintotwoorthogonal
components(electricandmagnetic)p ( g )
Referredtohorizontalandvertical
Simpleharmonic(orcarrier)wave,wheretheamplitudeoftheelectricvectorvariesinasinusoidalmanner,thesetwocomponentshaveEXACTLYthesamefrequencyp
q y
SignalPolarization
Thesetwocomponentshaveotherdefiningcharacteristicsthatcandiffer:
Twovectorcomponents maynothavethesameamplitude
Twovectorcomponentsmaynothavethesamephase,thatisthey may not
reach their maxima and minima at the same time
intheymaynotreachtheirmaximaandminimaatthesametimeinthefixedplane
LinearSignalPolarization
Electric Field
LinearPolarizationoccurswherethetwovectorcomponentsareinphase
Directionoftheelectricvectorintheplane,p
,whichisdeterminedbythevectorsumofthetwoorthogonalcomponents,willalwaysfallonasinglelineintheplane
Thedirectiondependsontherelativeamplitudeofthesetwovectorcomponents
Linearpolarizationcanbeinanyangleinthe
Electric Field
Magnetic Field
plane,butonceset,itnevervaries
CircularSignalPolarization
Ci l l i i h
hCircularPolarizationoccurswherethetwoorthogonalcomponentsareexactly90degreesoutofphase
Bothcomponentshaveexactlythesameamplitude
Onecomponentisatzero(reference)when the other component is
atwhentheothercomponentisatmaximumorminimumamplitude
Therearetwopossiblephaserelationshipsthatsatisfythisrequirement:
Thexcomponentcanbe90degreesaheadoftheycomponent
Thexcomponentcanbe90degreesbehindtheycomponent
CircularSignalPolarization
I thi th l t i t i
thInthiscase,theelectricvectorintheplaneformedbysumming,thetwocomponentswillrotateinacircle
Thedirectionofrotationwilldependonwhichofthetwophaserelationshipsexists
Dependingonwhichwaytheelectricvectorrotates,therearetwoalternatives
Righthandcircularpolarization Lefthandcircularpolarization
SatelliteLinkBudget
Theprocessofcorrectlysizinguplinkanddownlinkpaths Designed for a
specified availabilityLink Budget Analysis
Designedforaspecifiedavailability Musttakeintoaccount:
Establishedsatelliteperformance Path Loss (22,300 miles in
space)
LinkBudgetAnalysis
PathLoss(22,300milesinspace)
Atmosphericeffects(weather,ionstorms,sunspots,etc.)
Frequencybandsused(Ku,C,Ka) Hubuplinkantennaandamplifierperformance
Downlinkantennasizeandreceivernoisefigure
Assignstransponderuplinkanddownlinkfrequencies
LinkBudgetsmustaccountforanyMeshTDMAcarrier
requirements
Remotesitelevelsandcommissioningprocessmorecriticalthanever(Mesh)
CarrierTypes
Thereareawidevarietyofcarriertypes Eachhasitsownadvantages The
most common are: Themostcommonare:
SCPC SingleChannelperCarrier TDMA TimeDivisionMultipleAccess
D TDMA Deterministic Time Division Multiple Access DTDMA
DeterministicTimeDivisionMultipleAccess DVBS
DigitalVideoBroadcasting Satellite DVBS2 DigitalVideoBroadcasting
2nd Generation
SingleChannelperCarrier SCPC
TermSCPCcomesfromolderanalogtransmissiontechnology,whenasinglelli i
ld l d h lsatellitecarrier couldcarryonlyonedatachannel
Usedforeconomicaldistributionofbroadcastdata,digitalaudioandvideo,aswellasforfullduplexortwowaydata,audio/videocommunications
d d h ll l l ll
Userdataistransmittedtothesatellitecontinuouslyonasinglesatellitecarrier
Thesatellitesignalcarriermaybereceivedat
Singlelocation,indicatesapointtopointlink(SCPCSCPC)
Manylocationsinabroadcastmode,providesconnectivityamong
multiple,geographicallydispersed,pointtomultipointsites(SCPCTDMA)TDMA)
SCPCcanbereferredtoasTDM,orTimeDivisionMultiplexedCarrier
Multiple,colocatedbasebandinputsourcesaremultiplexedtogetherusing
Time as a controlling factor for a common output
carrierTimeasacontrollingfactorforacommonoutputcarrier
TimeDivisionMultipleAccess TDMA
TDMAisamechanismforsharingasatelliteuplinkchannelamongmultipleremotes
Usershaveaccesstothewholechannelbandwidthforsmallperiodsoftimeknownasatimeslots
AlluserscontendforavailablebandwidthbasedonQoS
settingsandotherrelatedprioritycontrolparameters
Demandisrequestedbytheremotesiteandisassignedbythenetworkhubwhenbandwidthisavailable
Nomechanismtocontroltimeslotrequestsfromremotes
DeterministicTimeDivisionMultipleAccess DTDMA
Preventscollisionsthatcanoccurwhenmultipleremotestransmitsimultaneouslysimultaneously
Networktimingprovidedbysynchronizedbursttimeplan
Timeslotassignmentsprovideguaranteeddelivery Improves throughput
and reduces latency by reducing/eliminating
Improvesthroughputandreduceslatencybyreducing/eliminating
retransmissions
DigitalVideoBroadcasting DVBS2
EnhancedDVBSStandard
IntroducedIPtransportincludingMPEG4audio/videop g
Optimizesbandwidthutilizationbydynamicallychangingtransmissionparameters
AdaptiveCodingandModulation(ACM)
VariableCodingandModulation(VCM)
ImprovedForwardErrorCorrection(FEC)
Increasescarrierperformancearound30%overDVBS
InternetProtocol IP
IPisaConnectionlessProtocol
SpecifiesonlyBestEffort;providesunreliablepacketdeliveryNo
retransmission of IP packets NoretransmissionofIPpackets
Packetsdiscardedifnetworkresourcesareinsufficient
SourceanddestinationIPfacilitiesdonothandshake
Specifiestheformatofalldatap
IPsoftwareperformstheroutingfunction
Packetsaretreatedindependently
Packetsmaytakedifferentpathsthroughthenetwork
IPprovidespacketdeliveryservicetoTransportLayerprotocols
IPprovidescommon,consistent,universaladdressingtechnique
IPdefinessetofrulesthatembodypackettransmissionanddelivery
S ifi h t h ld k t ( ti T S d
Specifieshowroutersshouldprocesspackets(routing,ToS,precedence,fragmentation)
Specifieswhenandhowtogenerateerrormessages(ICMP)
Specifiesconditionsthatgoverndiscardand/orduplicationofpacketsp g /
p p
(multicast)
TransmissionControlProtocol TCP
TCPisaConnectionOrientedProtocol
SourceanddestinationMUSTagreetothetransmissionandreceptionof
informationPRIORtothetransferofusertraffic
Destinationmustagreetoreceivetheinformation
Alltransmissionsareacknowledged
Dictatesprocedurestoagreewhentransferiscomplete
Specifiestheformatofinformation
Specifiesacknowledgementsthatinformationwasreceived
Specifiesmethodtoensureinformationwasreceivedcorrectlyp y
ResponsibleforFlowControl
Determineshowamachinedistinguishesbetweenmultipledestinations
Providesguaranteedendtoenddelivery
Providesrecoveryfromerrors,lost,andduplicatedpacketsy p p
RetransmissionisREQUIREDifacknowledgementisnotreceived
TCPandIPoperateoverdialup,LAN,Optic,highandlowspeedWANs
LatencymustbeovercomeforTCPtobepracticalonsatellitelinks
TransmissionControlProtocol TCP
TCPMultiplexesandDemultiplexes datato/fromapplications
Mustdistinguishdataflowsbetweendestinations
UsesPortIDsanddestinationIPaddresstodistinguishflow
ATCPPortisaqueueintowhichTCPplacesdatagrams
Employeesconnectionabstractionssuchas:p oyees co ect o abst act o s
suc as
Source/DestinationPort(s) HostAddress:Port
and/orSourceAddress:Port pairings
Source(65.168.20.1:100) Destination(10.10.200.1:200)S d d ti ti
i i t id tif d t fl
Sourceanddestinationpairingtoidentifyadataflow
Requiresonlyonelocalporttoaccommodatemanydataflowsformanylocalapplications
Encapsulatesdatatraffic(IPPacket) IPPacketsarethepayload
IPPacketsarethesinglepacketsthattraversethenetwork
InaroutednetworkOSILayer3packetsliveonlypointtopoint Ethernet
packets live only between adjacent
portsEthernetpacketsliveonlybetweenadjacentports
UserDatagramProtocol UDP
i C i l S iUDPisaConnectionlessService
BestEffortpacketdeliveryserviceS d i f ti ith t t t t b
Sourcesendsinformationwithoutrespecttoagreementbyanydestinationtoreceivetheinformation
Noacknowledgementsprovidedbyrecipientf d l
Noguaranteeofdelivery
Ifnotreceived,missingpacketsareneverresent
Appropriateforrealtimeapplicationssuchasvoice/video
DVBSorDVBS2LinearDeliveryBlockDiagram
DVBSorDVBS2HD/SDLinearSystemBlockDiagram
ProAudioSystemDiagram
ProVideoSystemDiagram
Summary
AspectsofdeliveringIPconnectivitytoatransmitter
Geosynchronoussatelliteorbit Communicationssatellitecomponents
Polarizedsignalstheory Carriertypes IP/TCP/UDP
IPinbroadcastcomponents
Thankyou
