1. JPL Standards Program 9 January 2001 PMBS 1 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE Mission Operational Environments & Protocol Considerations Peter Shames JPL Information Systems Standards Manager 9 January 2001

2. JPL Standards Program 9 January 2001 PMBS 2 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE Contents Characterize “Space” Mission Operational Environments –Space is a big place, there are several regimes –Considerations on communication protocol design Relationship between TCI/IP and CCSDS protocols Some Thoughts on “IP in Space”

3. JPL Standards Program 9 January 2001 PMBS 3 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE Space Environmental Characterization Achievable data rates (the laws of Physics) and link asymmetries Link margins (the 1/R**2 problem) Round Trip light time (RTLT) delays Link SNR and associated bit error rates Presence of fade, multi-path signals and interference Link discontinuities Presence (or lack) of communications infrastructure Connection establishment rules (as function of data rates and link characteristics) AOS/LOS considerations

4. JPL Standards Program 9 January 2001 PMBS 4 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE There are Many “Space” Environments "Local or Wired" Environments (terrestrial, facility on planet surface, or on S/C) "Nearby, Wireless/Unconstrained" Environments (wireless networking, nearby on planet surface, or between nearby S/C in "formation") "Nearby Constrained Wireless" Environments (may be terrestrial, nearby on planet surface) "Circum-planetary" Environments (up to GEO (or other planet) orbit, or among S/C in “constellation” orbits) "Deep Space" Environments (beyond Lunar orbit)

5. JPL Standards Program 9 January 2001 PMBS 5 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE "Local or Wired" Environments Terrestrial, or facility on planet surface, or on S/C: High signal to noise ratio Very high bandwidth and channel capacity Negligible RTLT Symmetric data paths Continuous connectivity (LAN) No significant bandwidth constraints Significant infrastructure in existence, easy to augment This is the environment for which TCP/IP was designed

6. JPL Standards Program 9 January 2001 PMBS 6 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE "Nearby, Wireless/Unconstrained" Environments Wireless networking, nearby on planet surface, or between nearby S/C in "formation": Moderate signal to noise ratio Potentially high bandwidth and channel capacity Low RTLT Symmetric data paths Typical continuous connectivity (WAN-like) Few bandwidth or channel constraints (terrestrial bandwidth allocation issues and frequency coordination issues for RF links) May have power,mass, and noise considerations May be existing infrastructure

7. JPL Standards Program 9 January 2001 PMBS 7 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE "Nearby Constrained Wireless" Environments Terrestrial, or nearby on planet surface: Moderate to poor signal to noise ratio (mass & power limitations) Moderate bandwidth, constrained channel capacity (mass & power limitations; 10’s Kbps) Low RTLT Moderately asymmetric data rates Intermittent connectivity (function of deployment, infrastructure, and orbits) Data rate constraints related to power availability Will have power, weight, noise, and signal path considerations May not be existing infrastructure Wireless Internet approaches may have applicability, current research topics

8. JPL Standards Program 9 January 2001 PMBS 8 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE "Circum-planetary" Environments Up to GEO (or other planet) orbit, or among S/C in “constellation” orbits: Moderate signal to noise ratio (mass & power limitations) Constrained bandwidth and channel capacity (possible regulatory, mass & power limitations; 100’s of Kbps) RTLT up to 1/2 second (or up to 6 sec at Lunar distances) Possibly symmetric signal paths (depends upon S/C power & aperture size) Possibly dis-continuous or continuously changing connectivity (depends on orbits & mobile stations, introduces link establishment and flexible routing issues) Frequency coordination and utilization issues for RF links near Earth Off-Earth infrastructure absent and costly CCSDS Proximity-1 and Internet protocols modified for space (SCPS) have potential applicability

9. JPL Standards Program 9 January 2001 PMBS 9 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE "Deep Space" Environments Deep Space - beyond Lunar orbit: Low to very low channel signal to noise ratio (build in a 3dB downlink margin) Low to extremely low channel capacity (extreme mass & power limitations, 10’s of Kbps max) Extreme RTLT (10's of seconds to many 10's of minutes) Assymmetric signal paths (large aperture(70M) w/ high power(20KW) antenna on ground; small(1M), low mass and power(40W) RF in space) Highly discontinuous connectivity (depends on orbits & large aperture station availability / viewperiods) Frequency coordination issues for RF links No comm infrastructure in place outside Earth This environment mandates specialized coding, modulation, link and upper level protocols

10. Radio Frequency and Modulation Link ARQ TM Space Data Link Protocol AOS Space Data Link Protocol Proximity 1 Space Data Link Protocol TC Space Data Link Protocol Communications Operation Procedure 1 Space Data Link Security Mechanisms Time Codes Lossless Data Compression Lossy Data Compression Reed-Solomon Coding BCH Coding Convolutional Coding Turbo Coding TLM Frame Sync. CLTU and PLOPs Synchronous LinksAsynchronous Links Networked CCSDS Space/Ground Communications Protocol Stack Physical Link Network Transport Application Internet RFC Draft CCSDS RecommendationCCSDS RecommendationCCSDS Report Onboard Navigation Internet IPSec SCPS-SP Space Security Protocol Space Packet Protocol SCPS-NP Space Network Protocol Internet Protocol (IPv4, IPv6) Store and Forward Interactive SCPS-FP Space FTP Internet FTP Internet TCP/UDP SCPS-TP SpaceTCP/UDP CCSDS File Delivery Protocol (CFDP) Space Packet Protocol Space Packet Protocol Onboard Bus and LAN Standards Onboard Comm Standards SOIF: Spacecraft Onboard Interface Standards Space App. Standards

11. JPL Standards Program 9 January 2001 PMBS 11 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE Mapping CCSDS to the Internet IP ATM SCPS-FP SCPS-TP CCSDS Link WAN Modulation (DWDM, etc.) CCSDS Coding (R-S, Conv, Turbo, BCH) +Modulation SCPS-SP CCSDS Path SCPS-NP FiberCopperCCSDS Space RF CFDP WAN Adaptation and Framing (DS-3, SONET, HDLC, etc) IPSec TCP, UDP FTP Terrestrial InternetSpace Internet

12. JPL Standards Program 9 January 2001 PMBS 12 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE Thoughts About “IP in Space” What do users really want from “TCP/IP” –Familiar interfaces on ground –Ease of use and development –Lower cost where possible –Do they really want to run web servers in space, with all that that implies? TCP/IP is the most widely supported stack of communications protocols on Earth –Cost effective, good performance, reliable & robust (depending on options chosen) –Familiar interfaces and functionality for developers and users TCP/IP stack was developed for terrestrial applications –Assumes continuous connectivity, low noise, symmetric links, low latency, short RT times, and data loss == congestion –Protocols at all levels assume ability to “handshake” whenever necessary –Largely dependent upon existing infrastructure and resources (relative to space) TCP/IP can be tuned to operate in local “space” environments –Will work where basic protocol assumptions are not violated (see above) –SCPS stack is TCP/IP adapted for space

13. JPL Standards Program 9 January 2001 PMBS 13 TELECOMMUNICATIONS AND MISSION OPERATIONS DIRECTORATE More Thoughts About “IP in Space” Use TCP/IP where it makes sense –Terrestrial environments including wireless (when protocols are matured) –On board S/C where there are adequate resources –Where there is sufficient bandwidth, signal strength, and other conditions are met (link symmetry, short RTLT, low noise, continuous coverage) –Use CCSDS link layer (and upper layer) protocols where they are required –On board S/C where there are modest resources –Where there is low bandwidth, high noise, long RTLT and other conditions that drive their use (low signal strength, link asymmetry, discontinuous coverage ) –Applicable also to moderate to high SNR, short RTLT, ARQ required for high reliability, asymmetrical data rates, variety of spacecraft (Proximity-1/CFDP) –Use engineered approach to integrate the protocols where useful –Transport TCP/IP frames over CCSDS links (possible with current stack) –Gateway from Internet (thru SCPS) where this is feasible and driven by space communication and mission operational requirements –Use application gateway to transport data / information structures where protocol gateway approaches cannot be used Work within existing standards bodies –Rely on CCSDS, IETF, IRTF expertise –Use requirements and architecture driven approach –Adopt, adapt or develop standards as required, in that order