VSATIntroduction

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VSAT - DefinitionVery Small Aperture TerminalIntelligent satellite earth station

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VSAT Networks - Definition Network of sites linked via satellite: From 3 sites to thousands All sites view the same transponder All share the same bandwidth

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ApplicationsRetail Networks Point-of-Sale (POS)Banking, inventoryGamingReservations Corporate NetworksInternet/Intranet accessCorporate voice File transfersVideo-conferencing

Rural telephony and network extensionsPSTN extensionsPayphonesWLL interconnections High-speed internet accessBrowsingE-mailInternet trunkingE-commerce

Video Applications

Distance Learning

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Typical Network ArchitectureIDU

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VSAT Networks - ComponentsIndoor Unit (IDU)Hub Traffic TerminalNetwork Management System (NMS) Indoor ElectronicsVSAT Traffic TerminalIndoor ElectronicsOutdoor Unit (ODU)Communications EquipmentHub Traffic TerminalVSAT Traffic Terminal

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Star NetworksSmall configurations at the remoteSmall antennas (as small as 1.8 m)Simple IDUsLimited HPA power (1 to 5 W) Large configurations at the hubLarge antennas (as small as 3.8 m)Complex baseband equipmentNMS located at the hub

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Mesh NetworksEvery site can talk to any other siteNo hub is requiredNMS remains requiredLarger configuration at the remote sites:Larger antennas (as small as 2.4 m)More complex IDUsBigger HPA size (5 to 20 W)Smaller number of sites than in star networks

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Frequency BandsC-BandBenefitsLower Rain AttenuationLower Space Segment CostAvailable EverywhereWider, Even Global CoverageSome limitationsTerrestrial InterferenceLower Antenna G/TLarger AntennasKu-bandBenefitsLower or no Terrestrial InterferenceMore Satellite PowerHigher Antenna G/TSmaller AntennasIssues for network planningHigher Rain AttenuationHigher Space Segment CostLimited Coverage AreaNarrower Beam

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Satellite Access Techniques

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FDMA TechniqueFrequencyTransponder Layout:

Carriers access the transponder: - At the same Time - At a different Frequency

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TDMA TechniqueTransponder Layout:

Carriers access the transponder: - At a different Time - At the same Frequency

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VSAT Access TechniquesAlohaRandom packet transmissionAcknowledgement of the received packets by the hub Slotted-AlohaImprovement of the Aloha technique by implementing time slots Each VSAT will be synchronized with the master clock of the hubDetermined access (DA-TDMA)The hub allocates time slots to each VSAT for the length of its required transmission

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Demand Assignment MethodDemand Assignment Multiple Access (DAMA): Remote ask for a time slot or a frequency to transmit their trafficNMS attributes each remote a time slot or a frequency to transmit this trafficThe attributed frequency or time slot will not be released until the end of the transmissionOften used for voice traffic

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RF StandardsStandard digital transmissionVarious modulationsVarious packet sizesVarious protocolsDVB/IP transmissionCell-based transmission technologyAdopts MPEG-2 for video and audio source codingMPEG-2 permits combining of any type of digital information, e.g. video, audio or internet data into a single data stream IP is then encapsulated into 188-byte packetsWell suited to IP and video traffic

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VSAT Networks - BenefitsLow Terminal CostDistance InsensitiveRe-configurableFlexibleFast and Easy InstallationCommissioningOperationExpandingAllows Direct Interconnection between VSATsSuperior QualityHigh ReliabilityTransparentNetwork protocolsSignalingNo last mile problemBandwidth optimization => cost-effective solutionsAsymmetric configurationsMountable on Customers Premises

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VSAT - Decision Drivers Competitive SolutionTechnologyCustomer requirementTimingPerformance SatellitecapacityImplementation planImplementation CostMaintenance Cost

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Customer RequirementsApplication (Voice, Data, Video)Number and location of sites No of users will there be per siteNetwork Topology (Star, Mesh)Protocol Requirements (ATM, Frame Relay, IP, X25, ISDN)Signaling Requirements for voice traffic (R2, SS7)Quality Requirements for voiceMaximum Carrier Requirement (Bandwidth, Peak Traffic)Link Availability Requirement (Blocking Probability, Equipment and Link Availability)Existing Equipment and its characteristicsFrequency Requirements (C-Band, Ku-Band)Terminal Requirements (Maximum Antenna size)Service Duration and Service Maintenance Requirements (Service Plan, Technical Training)

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Possible VSAT EquipmentCustomer requirements will determine:Network topologyTraffic type & sizeRequired interfacesExisting equipment to take into considerationWe can then narrow down the number of possible VSAT Equipment

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Traffic AnalysisThe voice traffic depends on:The chosen voice compressionThe blocking probabilityThe peak traffic requirement: number of voice channels and traffic in Erlang during peak hourThe data traffic depends on:The packet size and the number of packets transmitted by the applicationOr the data rate required in peak hours and the length of the peak hours

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Traffic AnalysisInternet traffic is highly asymmetricRatio 4:1 used for Outbound/Inbound ratio Low end customer requires 64 kb/s Outbound, 10% of the time he is connectedHigh end customer requires 256 kb/s Outbound, 20 % of the time he is connectedVideo trafficCan be highly asymmetric: broadcastCan be symmetric: interactive video

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4PoS - The Skystar Advantage is widely used for PoS transactions environments, as well as with financial transactions in an SNA (Systems Network Architecture) environment.

Banking - Supported banking applications include ATM services, electronic funds transfer (EFT), financial data distribution and the creation of "floorless" stock markets.

SCADA -(Supervisory Control and Data Acquisition) Pipeline monitoring, earthquake and water control networks are widely served by Skystar Advantage.

Internet/Intranet Access - Using satellite technology enhanced by Gilats IP Acceleration technology, your users can enjoy enhanced data rates while accessing their corporate Web servers or Intranet sites.

Interactive Distance Learning - Skystar Advantage provides a perfect platform for you or your clients corporate training requirements, Featuring interactive communication with multicast capabilities, an optional Interactive Distance Learning (IDL) application provides on-line training directly to hundreds of trainees.The Skystar Advantage network consists of a hub, satellite channel and remote VSATs. In contrast to other VSAT networks, the hub architecture features internal hub switching for remote-to-remote circuit connectivity.The network also includes Ku-, C-, and extended C-band satellite channels from Intelsat, which provide the transmission medium interconnecting the hub and remote VSATs. Skystar Advantage provides reliable connectivity between the VSAT sites and the hub through a backbone protocol, which serves as a data link channel between the hub and the VSAT. There is one backbone link between every VSAT and the hub. An advanced, user-friendly Network Management System (NMS) provides centralized monitoring and control, statistics, alarms and events, network configuration and report generation.A remote terminal consists of a small outdoor antenna (typically 0.55 to 1.2 meters), an Outdoor Unit (ODU) and an Indoor Unit (IDU).

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