ground network optimization for optical leo downlinks€¦ · leo1: link planning lead time dlr.de...

Ground Network Optimization for Optical LEO Downlinks C. Fuchs et. al.

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• Introduction: ESA-project ONUBLA

• Investigated LEO scenarios

• Results • Comparison of various scenarios • Investigation of additional parameters

• Link Planning Lead Time • Buffer Size

• Conclusions

Outline

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• ESA activity „Assessment of access availability of space-ground optical links” (ESA contract number: 4000110718/14/NL/MV)

• Main project goal: Assess access availability of optical space-to-ground links, including limitations due to cloud coverage and atmospheric turbulence, considering different satellite orbits

• Several scenarios

• LEO downlink (covered in this presentation) • GEO feeder link • GEO relay link

Introduction: ESA project „ONUBLA“

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• DLR-Institute of Communications and Navigation, Oberpfaffenhofen (Prime, LEO scenarios)

• Airbus Defence & Space, Toulouse (GEO scenarios)

• Fraunhofer Heinrich-Hertz-Institute, Berlin (HHI) (Simulation software)

• Laboratoire d'Optique Atmosphérique, University of Lille (LOA) (Cloud database)

Project partners - consortium

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• Single database with high temporal and spatial resolution • All GEO sensor raw data (covers ~95% of Earth) processed with the same

algorithm Excellent comparability of cloud data for sites around the world

Worldwide cloud database

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Satellite

GEO Cloud data

MSG MTSAT GOES

LEO Cloud data

MODIS AQUA/TERRA

Instrument SEVIRI MTSAT-1R GOES I-M MODIS

Time resolution 15 min 30 min – 60 min 30 min 2 day + 2 night overpasses

Spatial resolution 4 km 1km-4km 1km-4km 1km – 5 km

Cloud Type detection

Scene Classification Cloud Mask + Type

Scene classification with adapted SAFNWC cloud mask

Cloud mask with 4 level confidence

Time span available 5 years 5 years 5 years 5 years

Coverage Geo FOV GEO TBC

Procurement Eumetsat / SAFNWC ICARE / SAFNWC ICARE / SAFNWC ICARE / Collection 6

NASA

Additionnal information

Cloud top altitude (CTOP) CTOP CTOP

Cloud Top altitude Cloud Optical

Thickness

• Inputs • Satellite orbit • OGS network sites • Data rate • Buffer size • Data acquisition rate • Link Planning Lead Time • …

• Enables simulation of key parameters for application of optical links

Simulation tool

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• Conclusions

Outline

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Investigated LEO downlink scenarios

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Scenario n° OGS locations Interest

Scenario L1 Europe OGS network in Europe

Scenario L2 Europe and Africa Additional stations in Africa improve overall availability, as seasonal effects are balanced

Scenario L3 Europe and selected polar sites Polar ground stations benefit from more frequent satellite passes (for polar orbits), but usually suffer from worse weather

Scenario L4 Worldwide OGS network for international cooperation

Scenario L5 Worldwide: ESA, NASA & DLR Already existing space-communication sites with heritage (e.g. ESA-ESTRACK, NASA-DSN, DLR-Sites)

Scenario LEO 1: Optical Ground Stations (Europe)

> ONUBLA LEO System Consolidation > C. Fuchs, DLR • 4/11/2016 DLR.de • Chart 9

Scenario LEO 5: Optical Ground Stations (Space agency sites)






• Conclusions

Outline

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• Definition of reference mission • Data volume: 500 Gbit / orbit • Data rate: 8 Gbps • Buffer Size: 1.5 Tbit • Satellite Orbit: Sentinel 1 (693 km, LTDN: 6 am) • Link Planning Lead Time: 0 hours

• Presentation of results • Mean annual data throughput in Gbit/day vs. number of OGS • Percentage of data transmitted vs. number of OGS

Comparison of all 5 LEO scenarios


Comparison of throughput


Comparison of percentage of data transmitted (within 1 orbit from image acquisition)


• E.g. scenario LEO 5, 8 OGS: • 57% of all acquired data transmitted within 0.5 orbits • 82% of all acquired data transmitted within 1 orbit • 90% of all acquired data transmitted within 1.5 orbits • 98% of all acquired data transmitted within 3 orbits

Overview of „percentage of data transmitted“ within different latency constraints


Scenario Number of OGS 4 8 12

LEO 1: Data transmitted within 0.5 / 1 / 1.5 / 3 orbits 23% / 42% / 50% / 70% 30% /51% / 60% / 79% 32% / 55% / 61% / 80%

LEO 2: Data transmitted within 0.5 / 1 / 1.5 / 3 orbits 28% / 46% / 52% / 72% 32% / 53% / 60% / 79% 34% / 55% / 61% / 80%








• Conclusions

Outline

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LEO 1: Influence of buffer size

DLR.de • Chart 17 > ONUBLA LEO System Consolidation > C. Fuchs, DLR • 4/11/2016

LEO 4: Influence of buffer size

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Larger buffer enables substantially smaller data loss with fewer OGS

> ONUBLA LEO System Consolidation > C. Fuchs, DLR • 4/11/2016

• Clear effect of link planning lead time

LEO1: Link Planning Lead Time

DLR.de • Chart 19 > ONUBLA LEO System Consolidation > C. Fuchs, DLR • 4/11/2016

• The ESA-project ONUBLA and the developed simulation tool has been presented

• Optical Ground Station networks with larger spread around the grobe enable the transmission of larger amounts of data with lower latencies

• If no particular latency requirement is given by a mission, an increased buffer size enables transmission of almost all acquired data with relatively few ground stations

• The Link Planning Lead Time plays an important role in terms of achievable data throughput; For maximum throughput, the downlinks should be commanded with low lead time, or (alternatively), the terminal must be able to operate autonomously

Conclusions

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Acknowledgement: • Nicolas Perlot, HHI (Software) • Jerome Riedi, Univ. of Lille (Cloud data base) • Sylvain Poulenard, Airbus Defence and Space (GEO scenarios) • Josep Perdigues, ESA (Technical Officer)

Thank you very much for your attention!

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ground network optimization for optical leo downlinks€¦ · leo1: link planning lead time dlr.de...

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