Overview of Space Communications Protocols - CCSDS
Overview of Space Communications Protocols - CCSDS
Overview of Space Communications Protocols - CCSDS
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<strong>CCSDS</strong> REPORT: OVERVIEW OF SPACE COMMUNICATIONS PROTOCOLSThe Proximity-1 <strong>Space</strong> Link Protocol—Data Link Layer uses a triad <strong>of</strong> multiplexingcapabilities, which is incorporated for specific functionality within the link. The <strong>Space</strong>craftIdentifier (SCID) identifies the source or destination <strong>of</strong> Transfer Frames transported in thelink connection based upon the Source-or-Destination Identifier. The Physical ChannelIdentifier (PCID) provides two independently multiplexed channels. The Port ID providesthe means to route user data internally (at the transceiver’s output interface) to specificlogical ports, such as applications or transport processes, or to physical ports, such as onboardbuses or physical connections (including hardware command decoders).Table 3-1 summarizes the identifiers <strong>of</strong> the <strong>Space</strong> Data Link <strong>Protocols</strong>.IdentifiersTransfer FrameVersion Number(TFVN)<strong>Space</strong>craft Identifier(SCID)Physical ChannelIdentifier (PCID)Virtual ChannelIdentifier (VCID)Multiplexer AccessPoint Identifier(MAP ID)Table 3-1: Identifiers <strong>of</strong> <strong>Space</strong> Data Link <strong>Protocols</strong>TM <strong>Space</strong>Data LinkProtocolAlways 1(binaryencodednumber is 00)TC <strong>Space</strong>Data LinkProtocolAlways 1(binaryencodednumber is 00)AOS <strong>Space</strong>Data LinkProtocolAlways 2(binaryencodednumber is 01)0 to 1023 0 to 1023 0 to 255 0 to 1023N/A N/A N/A 0 to 10 to 7 0 to 63 0 to 63 N/AN/A 0 to 63 N/A N/APort Identifier N/A N/A N/A 0 to 7Proximity-1 <strong>Space</strong>Link Protocol—Data Link LayerAlways 3 (binaryencoded number is10)3.2.3 SERVICES PROVIDED BY DATA LINK PROTOCOLSThe <strong>Space</strong> Data Link <strong>Protocols</strong> provide several services to transfer a variety <strong>of</strong> data on aspace link. The most important service is a service to transfer variable-length data unitsknown as packets (i.e., protocol data units <strong>of</strong> protocols <strong>of</strong> the Network Layer). In addition tothis service, the <strong>Space</strong> Data Link <strong>Protocols</strong> provide services to transfer fixed- or variablelengthdata units with private (non-<strong>CCSDS</strong>) formats, short fixed-length data units forreporting on real-time functions, and bit streams.<strong>CCSDS</strong> 130.0-G-2 Page 3-4 December 2007
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