Proposal to Add an HDLC Framing Option to CCSDS Synchronization/Link Recommendations

10/28/2003

James Rash - GSFC Keith Hogie - CSC Ed Criscuolo - CSC Ron Parise - CSC Basic Proposal

• Add ISO HDLC frame synchronization as an option to TM/TC/AOS recommendations for data link frame synchronization

• Add IETF RFC 2427 multi-protocol data link frame header as an option to TM/TC/ AOS recommendations for data link

• This adds an option for to use data link formats that are supported by all common carriers and network equipment vendors’ synchronous serial interfaces

• It allows spacecraft data to be inserted directly into all national and international carriers Frame Relay and IP networks

• It supports encapsulation of IP and many other network protocols

• It provides an option that separates link frame sync and FEC coding sync which allows changing FEC coding type and block length independent of data link format

Oct. 28, 2003 CCSDS HDLC Proposal 2 HDLC Space Link Data Framing

• ISO/IEC 3309:1991(E), "Information Technology - Telecommunications and information exchange between systems - High-level data link control (HDLC) procedures - Frame structure", International Organization For Standardization, Fourth edition 1991-06-01 • HDLC FLAG bytes (01111110) between frames – no fill frames or packets – continual FLAG bit pattern when no data frames being transmitted • Bit stuffing to ensure no FLAG patterns in data or CRC • CRC-16 on end of frame for error detection • Variable length frames up to at least 4K Bytes

Bit stuffing applied

Flag Variable Length Frame Data CRC-16 Flag Flag Link Framing (1B) (2B) (1B) (1B)

HDLC Frame

Oct. 28, 2003 CCSDS HDLC Proposal 3 Frame Relay Space Link Data Framing

• IETF Multi-Protocol Encapsulation over Frame Relay (RFC 2427, STD 55) – Uses Frame Relay/HDLC - Not X.25 or LAP-B – No windowing, optional flow control - completely independent of delay • Frame Relay DLCI provides 1024 virtual channels • Standard Frame Relay processing supported by all telecom vendors • Normally one user data packet per variable length frame – No first header pointers or packet extraction processing – Any packet segmentation or fragmentation handled in upper layer protocols • Supports encapsulation of IP and many other network protocols

Frame Relay/Multi-Protocol Encapsulation Header

FR Hdr Encap Hdr Link Layer Header Frame Data (2B) (2B)

Flag Data CRC-16 Flag Flag Link Framing (1B) (2B) (1B) (1B)

HDLC Frame

Oct. 28, 2003 CCSDS HDLC Proposal 4 Fixed Length FEC Coding Blocks and HDLC • How do you put variable bit length HDLC frames in fixed byte length code blocks (e.g. Reed-Solomon, TPC, LDPC) ? • Separate data link framing and FEC coding from each other • Different approach from traditional CCSDS framing where transfer frame and R-S code block use the same attached sync mark (ASM) • HDLC inserts into fixed length R/S, TPC, LDPC codeblock as a bitstream and is extracted as a bitstream on the other end of link – In the commercial network world R/S, TPC, LDPC and convolutional coding are performed at the physical layer independent of HDLC data link framing – FEC has no relation to any framing present in the bit stream – HDLC provides sync mark independent of any optional coding sync marks • Separation of coding allows changing coding type and block length with no changes to HDLC framing

Variable Bit Length HDLC Frames HDLC Frame Data Codeblock Size number of Bits

Coding ASM R/S Sym ASM •••

Fixed Length FEC Codeblock

Oct. 28, 2003 CCSDS HDLC Proposal 5 CCSDS Compared to Commercial Layering

• Very similar except commercial world separates FEC and framing at a bitstream level interface Commercial Router/ CCSDS Frame Relay Switch

NP or IP NP or IP Net PDU IP IP

Frame HDLC Framing HDLC Framing Packet Insert Packet Extract VCDU Framing VCDU Framing FEC Encode FEC Decode FEC Encode FEC Decode

Randomize Derandomize 101010 Randomize Derandomize (bits) Conv. Encode Conv. Decode Conv. Encode Conv. Decode

Bit sync Bit sync

Modulator Demod Modulator Demod

Transmitter Receiver Transmitter Receiver

Upconvert Downconvert Upconvert Downconvert Antenna

Oct. 28, 2003 CCSDS HDLC Proposal 6 Current HDLC in Space Status

• Used for over 20 years in small educational and experimental spacecraft. • Over 80 past, present, or planned missions used or will use HDLC • Developed and operated by 23 universities, 8 amateur groups, and 7 commercial space entities in 24 countries • Also represented are NASA, the US Air Force, the US Navy, and the Chilean Air Force. • resources by Germany and Turkey, are currently in development and will use HDLC. • A Disaster Monitoring Constellation (DMC) by UK, Algeria, Nigeria, and Turkey is currently operational and uses HDLC with 8Mbps downlinks. • NASA’s CHIPSat is currently operational and uses HDLC • Future missions are selecting HDLC/Frame Relay for its flexibility, simple implementation, low-cost, and wide availability

Oct. 28, 2003 CCSDS HDLC Proposal 7 HDLC Spacecraft

Spacecraft Launch Year Owner Organization Owner Country Status

UoSat-1 1981 University of Surrey UK decayed UoSat-2 1984 University of Surrey UK operational AO-13 1988 AMSAT USA non-operational SAREX 1990 AMSAT USA multiple shuttle missions UoSat-3 1990 University of Surrey UK operational UoSat-4 1990 University of Surrey/ESA UK non-operational HealthSat-I 1990 SateLife USA operational Dove 1990 AMSAT-Brazil Brazil non-operational WeberSat 1990 Weber State University USA non-operational LUSAT 1990 AMSAT-LU Argentina operational PACSAT 1990 AMSAT USA semi-operational JAS-1b 1990 JAMSAT Japan operational UO-14 1990 University of Surrey UK operational SARA 1991 Astronomy France non-operational S80/T 1992 Matra Espace/CNES France operational KITSat-1 1992 Korean Advanced Institute of Science Korea operational Arsene 1993 ENSAE/CNES France non-operational PoSAT 1993 Portugal Portugal operational HealthSat-II 1993 SateLife USA operational KITSat-2 1993 Korean Advanced Institute of Science Korea operational ITAMSAT 1993 AMSAT-I Italy semi-operational AO-27 1993 AMRAD USA operational Cerise 1995 Alcatel Espace/DME France operational Fasat-A 1995 Chile Chile non-commissioned UNAMSAT-1 1995 University Program of Space Research Mexico failed launch UNAMSAT-2 1996 University Program of Space Research Mexico non-operational JAS-2 1996 JAMSAT Japan operational Fasat-B 1998 Chilean Air Force (FACH) Chile operational TechSat-1b 1998 IARC Israel unknown SEDSAT 1998 University of Alabama, Huntsville USA semi-operational TMSAT-1 1998 TMSC and MUT Thailand operational PanSat 1998 Naval Post-Graduate School USA operational Clementine 1999 Alcatel Espace(France) France operational SunSat 1999 Stellenbosch University South Africa non-operational

Oct. 28, 2003 CCSDS HDLC Proposal 8 HDLC Spacecraft (cont)

UoSat-12 1999 Surrey Technology LTD UK operational JAWSAT 1999 USAFA/Weber State Univ. USA unknown SNAP-1 2000 SSTL development satellite UK operational Tsinghua-1 2000 Tsinghua University, Beijing China operational Opal 2000 Stanford University USA operational ASUsat-1 2000 Arizona State University USA non-operational SaudiSat-1A 2000 King Abdulaziz City for Science & Tech Saudi Arabia unknown SaudiSat-1B 2000 King Abdulaziz City for Science & Tech Saudi Arabia unknown TIUNGSAT-1 2000 Astronautic Technology Maylasia operational AO-40 2000 AMSAT-DL Germany operational ARISS 2000 AMSAT USA in use on ISS PicoSat 2000 USAF USA unknown FalconSat I 2000 Air Force Academy USA operational Sapphire 2001 Stanford University USA operational PCSat 2001 US Naval Academy USA operational 2001 Project Starshine (NASA/USN/USAF) USA operational Emerald 2002 Stanford University USA in development ChipSat 2002 UC Berkeley USA in development CUTE 2002 Tokyo Institute of Technology Japan in development XI-IV 2002 University of Tokyo Japan in development 3 Corner Sat 2002 USAF/ASU USA in development HokieSat 2002 VA Tech (University Nanosat) USA in development AlSat (DMC) 2002 Algeria Algeria operational TopSat 2003 UK MoD and BNSC UK in development StenSat 2003 StenSat Group USA in development MOST 2003 University of British Columbia Canada in development Starshine 4 2003 Project Starshine (NASA/USN/USAF) USA in development Starshine 5 2003 Project Starshine (NASA/USN/USAF) USA in development NigeriaSat (DMC) 2003 Nigeria Nigeria operational BILSAT (DMC) 2003 Turkey Turkey operational UK-DMC (DMC) 2003 UK UK operational DTUsat TBD Technical University of Denmark Denmark in development AAU Cubesat TBD Aalborg University Denmark in development BiltenSat TBD Turkey Turkey in development RapidEye TBD RapidEye A.G. Germany in development PolySat TBD California Polytechnic University USA in development Citizen-Explorer TBD University of Colorado USA in development CESAR-1 TBD AMSAT-Chile Chile in development

Oct. 28, 2003 CCSDS HDLC Proposal 9