1. CCSDS 2009 Fall Meeting – ESTEC Noordwijk
SLS Planetary Communications SIG
Olivier Bompis / Jean-Luc Issler – October 30, 2009

2. SUMMARY CNES proposal for Lunar and Martian NavCom surface links:
Martian / Lunar Surface Links Requirements & Main Objectives.
CNES Mission profiles definition.
Benefits of reusing Space-to-Earth (MSS+RDSS/RNSS) bands.
Advantages of reusing terrestrial standardised waveforms for Com surface and return emergency links.
CNES studies & tools around Lunar / Martian NavCom problematic:
PhD thesis on OFDM signal processing for GNSS.
Phase 0 study: Geophysical Package for Seismological Lunar Network.
Interference Assessment Software (Interference Analysis for Space Com Systems).
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

3. Martian / Lunar Surface Links Requirements (Overview)
Need to address several different components…
Autonomous surface stations and exploration vehicles (i.e. rovers).
NavCom relays on surface or in orbit (surface beacons or satellites).
Future human lunar outposts (NASA Constellation) with EVAs.
… and several different needs, for example:
Low data rate, severely power constrained links (ie. surface platforms).
High data rate, power spectrum constrained links (ie. DatCom for EVAs).
Provide time synchronisation, ranging, and localisation.
Ensure reliability and availability regarding constrained reception environment.
Pictures from ALICE SEEDS IV mission analysis and NASA JPL ALGEP-NG paper
Data Relay Satellite
Rover
Outpost
Surface Beacon
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

4. CNES Mission profiles definition
 Primarily concerned with Surface & Proximity Links
Contribute to Lunar and Martian autonomous surface stations in providing geophysical instruments and Communications S/S for Surface Links (Around the International Lunar Network initiative).
Contribute to exploration Rovers in providing scientific equipment and Communication S/S for Surface Links (ChemCam on NASA Mars Science Laboratory, Proximity-1 Link intended on ESA EXOMARS).
EXOMARS Landing Platform Configuration
UHF Band Transponder
CHEMCAM Mast Unit
UHF Band Transponder
Proximity-1 Link « SMART UHF » for future robots or surface Platform
Very Broadband Seismologic Sensor
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

5. Benefits of reusing (MSS + RDSS/RNSS) Bands
Observe tendencies of current Terrestrial Radionavigation Satellite Service (RDSS/RNSS) to extend from L-Band to S-Band (cf. next WRC 2012 to open MSS bands for RDSS/RNSS to Europe/Africa & the Americas, in addition to Asia/Australia, where this dual attribution is already in place  Worldwide convergence between MSS & RDSS/RNSS).
The S-Band spectrum between and 2500 MHz (Mobile Satellite Services) can be reused for GNSS to allow interesting synergies with communications systems (cf. I. Mateu & al , “Exploration of Possible GNSS Signals in S-band”, ION GNSS September 2009: Session C5 Paper #7).
These should produce only in this band natural development of affordable RF components / receivers which provide both Radionavigation / Time synchronisation & data / voice communication capabilities (i.e. future GLOBALSTAR mobile phones with RNSS).
Applicability on Lunar / Mars Vicinity Frequency Plans ? Needs to be addressed separately from CCSDS SLS PlaCom SIG (SFCG – LMSCG attributes).
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

6. Advantages of reusing terrestrial standardized waveforms
For Communication Surface Links:
Standard use of OFDM modulation such as WiMax or DVB-SH should interest candidates to provide Communication capabilities for several actors on the surfaces of the Moon or Mars (robustness against multipath produced by constrained environment).
These waveforms allow Radionavigation and Time synchronisation capabilities considering the merge of (MSS + RDSS/RNSS) frequency bands (cf. next slides on OFDM signal processing for pseudo-range measurements).
Allows a simple adaptation, reliable, and affordable components well-sustained by international manufacturers.
For Return Emergency Links (manned missions needs):
Coupled with previous communication surface links, Return Emergency Links based on CDMA allocation (i.e. GLOBALSTAR IS-95 derived signal) allow us to adapt simple, reliable and affordable components used for terrestrial applications.
OFDM modulation could also provide the same advantage.
 Preliminary proposals ; to be discussed
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

7. CNES PhD Thesis on OFDM signal processing for GNSS
Thesis Objectives
Determine signal processing techniques on OFDM modulation for positioning (pseudo-range measurements).
Focus on DVB-T/-H/-SH family signals standards.
Thesis Contents
Propose a specific method for pseudo-range measurements in multipath propagation channels based on pilot symbols of DVB-T family signals.
Evaluate method’s performances in realistic propagation channels, with low SNR conditions.
Main Conclusion
A RDSS system using OFDM instead of DSSS/CDMA could provide comparable pseudo range measurements with an efficient use of available bandwidth and provide communication service.
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

8. CNES PhD Thesis on OFDM signal processing for GNSS
Contents (details):
Benefits in using the DVB-SH standard with OFDM access technique for providing positioning function with TDOA (from P. Thevenon & al “Positioning principles with a mobile TV system using DVB-SH signals and a Single Frequency Network”, Digital Signal Processing, th International Conference).
Performance on pseudo range accuracy is comparable to that of CDMA with a similar bandwidth. Multipath error on ranging is limited vs. GPS C/A.
Parameters:
2048 FFT size (2K mode).
Signal BW: 5 MHz.
Loop noise BW: 10 Hz.
Amplitude (2nd path) = 0.5 * LOS.
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

9. CNES Phase 0 Study: Seismological Lunar Network
Study Objectives
Build-up a core station to perform seismologic analysis on lunar surface.
High constraint on available power (using solar energy only).
Analyse communications scenarios (DTE / Relay) depending stations locations.
Study Contents
Trade-Off between S-Band for DTE-DFE/Relay and UHF for Relay links.
Links and Power budgets which allow optimal configuration.
Results & Improvements
Potential interest to use an “hybrid” S-Band design for DTE and Relay links.
Frequency bands : potential interest of « popular » wireless designs (GSM / IEEE – standards) for proximity surface links.
Modulations / Coding schemes: performance analysis of LDPC AR4JA vs. CCSDS Turbo-Coding.
Next Steps: Lunar and Mars “Communication & Navigation” Infrastructure Design (2010 prospective phase 0 study) + CNES membership in inter-agencies working groups on NavCom aspects (CCSDS PlaCom SIG, ILN WG 02).
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

10. Interference Assessment Software: what is available ?
Developed in C under JUZZLE environment
Modularity (libraries and computation blocks).
Compatibility with WINDOWS and LINUX.
User-friendly interface.
Models available
Orbit propagator J2 (CNES MSLIB90 free library) in line with “Calculation of GPS and GALILEO Satellite Positions in ECEF Coordinates” Informal note form US RFC Subgroup Team, 29 June 2006.
Orbit propagator SGP4 / SDP4.
CNES DCT/RF/ITP propagation DLL, referenced at ITU.
Link budget and SSC calculus.
Scenario set-up
Possibility to set-up any constellation based on TLE or on Kepler parameters.
Possibility to set-up any user-defined antenna radiation pattern (, gain).
Possibility to set-up any user-defined spectrum.
Possibility to define precise surface station location or a grid of receivers.
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

11. Comparisons between IAS and other RFC group tools
Link budget comparisons have been done between IAS results and UniBW tool results
Received power show an offset of 0.85 dB for GPS PRN1 satellite.
Received power show an offset of 0.93 dB for Galileo PRN51 satellite.
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP

12. Thank you for your attention
SLS PlaCom SIG – CCSDS Fall Meeting 09 – CNES DCT/RF/ITP