1. Optical Link Study Group Report
CCSDS
Optical Communications BOF
John Rush (NASA) and Klaus-Juergen Schulz (ESA) October, 2013

2. Agenda Introduction OLSG Objective
Schedule of Agency Optical Communications Demonstrations
OLSG Final Report Review and Findings
IOAG-16 Action Results
Next Step: IOP-3 Briefing Overview

3. Introduction
Numerous IOAG Agencies are experimenting with Optical Communications, and starting first operational capability
Optical Communications is in early stage development
Agencies are experimenting with different techniques
ESA/DLR starting earth relay services with EDRS/Sentinel
In 2010 the OLSG was chartered by the IOAG to determine if there was a business case for Cross Support in Optical Communication and it was determined that there is such a case.
The OLSG was formed with seven member Agencies: ASI, CNES, DLR, ESA, JAXA, KASI, and NASA.
The IOAG requested that OLSG do further studies to identify the types of standards that would be needed to enable Cross Support in Optical Communication
The OLSG is reported its findings to IOAG-17 and the IOAG-17 brought forward a recommendation to IOP-3 in June of this year.

4. OLSG Process
Surveyed existing optical communications projects among the agencies
Identified significant issue in dealing with Atmospheric conditions (i.e. clouds, optical turbulence) and began detailed study of how to improve availability
Developed scenarios in order to prove feasibility based on statistical analysis of cloud data for scenario ground terminal locations
Identified guidance for the development of cross support standards

5. Agencies Already Engaging in Optical Communications Experiments
2012
2013
2014
2015
2016
2017
2020
2025
Technology Demonstrations
TerraSar-X (DLR)
2009 LEO-ground demo
1064 nm, Homodyne BPSK
OPALS (NASA)
ISS-ground demo
1553 nm, OOK modulation
LLCD (NASA)
2013 Moon-Earth demo
1550 nm, single photon detection and PPM
Sentinel/EDRS (ESA)
2014 ISL
1064 nm, Homodyne BPSK
LCRD (NASA)
2017 GEO-Ground and ISL LEO-GEO
1550 nm, direct detection PPM
TDRS (NASA)
2025 GEO-Ground Operational Relay
1550 nm, DPSK and high speed routing
TerraSar-X (DLR) to NFIRE (USAF)
2008 ISL LEO-LEO demo
1064 nm, Homodyne BPSK
OSIRIS (DLR-ICAN)
2014 LEO-Earth demo
1550 nm, IMDD
Optel-µ (ESA)
2017 LEO-Earth demo
direct detection and PPM
DOT (NASA)
2020 Mars-ground
1550nm, direct detection PPM
LCT-135/Alphasat (ESA)
2013 ISL, GEO to Earth demo
1064 nm, Homodyne BPSK
SOTA (NICT)
LEO to ground demo
1064 and 1550nm, OOK modulation

6. Analysis of Availability
Developed models of various scenarios using optical communications for mission data
Assumed all missions would have RF link for spacecraft commanding
Missions modeled after existing missions
NASA weather model used to support analysis
Statistical model of cloud coverage
Developed yechniques for evaluating impacts of “Cloud Free Line of Sight (CFLOS)” on mission success in terms of amount of data return

7. Example Scenario – L2 CONOPS: Space Segment: Ground Segment:
Modeled based on the EUCLID mission (operations always in night time)
7.5 Tb data volume per day
3 days of onboard storage (22.5 Tb)
3 hr of Cloud Free Line of Sight (CFLOS) required per day
Link budget developed for 700 Mbps data rate, favorable Sun-Probe-Earth (SPE) angle, i.e. ground terminal always looks into the dark sky.
Space Segment:
Could be derived from LLCD or TESAT LCT-135 terminals
13.5 cm aperture
5 W transmit power
50 kg, 160 W
Ground Segment:
Terminal with 1m Rx aperture telescopes, 8x 15cm Tx telescopes with 50W/aperture
Two ground terminals: Tenerife and Ascension, Tenerife and Hartebeesthoek

8. Example L2 Scenario Analysis
Link Budgets:
Downlink Link Budget, 1m Rx aperture
Uplink Link Budget
8x 15cm apertures to minimize effect of atmospheric turbulence instead of radiating through the Rx aperture
Calculation of Nominal Ocular Hazard Distance (NOHD) based on continuous wave, 1550 nm , to not exceed the Maximum Permissible Exposure (MPE) of max 0.1 W/cm2
Laser Communications Network Optimization Tool (LNOT) computes Cloud free line of sight (CFLOS) and availability
Overall Percentage Data Transmitted (PDT): 99.89%
Cumulative distribution of monthly PDT
Probability of exceeding PDT

9. Space-Earth Scenario Analysis Summary
Scenarios
Unit
LEO
Lunar L2 L1
Deep
Space
(Mars)
Single Relay Optical FL
(Case b)
Scenario ConOps
Data Volume per day
Tb/d 12
5.72
7.5
1.1
216
Onboard Storage Tb
2.3
7.4
22.5 10
Data Rate per second
Mb/s
10,000
622
700
CFLOS required per day
h/d
0.33
2.55 3
1.2 6
Onboard Terminal
Aperture cm 8
13.5 22
Tx Power W
0.5 5 4
2.2
Mass kg 35 30 50
< MRO Ka
Power Consumption
120
140
160
Ground Stations
Rx Terminal Size diameter m
0.4 1
Tx Apertures and Size
4x 5cm
4x 15cm
8x 15cm
9x 7cm
Tx NOHD ICAO (1550nm)
451
12,111
27,080
32,042
42,125
6,055
Tx NOHD Near Field (1550nm)
4,094
24,574
29,957
42,068
Number of Terminals 7 2
Location of Terminals
Haleakala, TMF, Madrid, Svalbard, La Silla, Tenerife,
New Norcia, Hartebeesthoek
Haleakala, Tenerife
Tenerife, Hartebeesthoek
WSC, Tenerife,
La Silla
PDT resulting %
94.8
97.4
99.9
98.5
99.0
98.0

10. Additional Study of Intersatellite Cross Links
In addition to the main concentration of OLSG on space to ground links, intersatellite cross links were also studied
It was found that there are two wavelengths being used, or planned for use, by the member agencies: 1064 nm and 1550 nm
OLSG believed it would be best to narrow the possible wavelengths to these two
Further demonstrations and use of the wavelengths will provide additional data on performance in the future but it is too early now to narrow the selection further now

11. OLSG Findings Presented to IOAG-16
OLSG determined that there is a business case for cross support among the IOAG Agencies
Due to the unique disruptions to optical communication links by atmospheric conditions additional coordination of handovers to alternate ground stations is necessary and should be included in the standardization set
Another source of potential disruption to optical communications links is caused by aircraft so a dialog should take place with the International Civil Aviation Organization (ICAO) to find ways to minimize the disruptions
IOAG requested that OLSG conduct further analysis and assigned an Action to OLSG
Determine the new standards that must be developed by CCSDS, as well as identify the existing CCSDS standards that can be re-used for Optical Communications Cross Support
Provide guidance for development of standards that relate to the coordination of ground optical communication stations
Considering the exchange of necessary atmospheric conditions
Coordination of handovers from one ground station to another
Provide a recommended IOP-3 briefing outline to IOAG-17 that presents the case for endorsement of optical communications cross support by the IOP and agreement to proceed with the standardization process
Determine resource estimate and schedule for standardization of optical links including necessary ground coordination

12. OLSG Findings on Reuse of Existing CCSDS Standards
A team of optical communication experts was formed:
NASA
ESA
DLR
CNES
JAXA
The team considered standards available at each layer and determined that everything at the CCSDS frame layer standards and above is reusable and does not have the be developed for optical communication cross support

13. Re-use of Existing Space-Ground CCSDS Standards
DELTA DOR
PN RANGING
Prox - 1
TM, TC
LTP
DTN
BP/BSP
Channel Coding and Sync
IPv6
Space Packet
Protocol
CFDP
IPv4
AOS
RANGING
Encap
SECURITY
RF & Modulation
SLS AREA
DATA
COMPRESSION
Services
Reuse existing standards for optical communications
Must be developed for optical communications cross support

14. Guidance on New Standards
Optical Communication
Space to Ground Standards
Ground station
coordination requires
meteorological forecasts
and handover coordination
Space-Ground Connection
Agency A
Next Space-Ground Connection
Spacecraft
MOC A
Meteorological Data
NOC A
Agency B
Handover coordination
including meteorological data
Meteorological Data
NOC B

15. New Optical Communication Standards Needed
Green Book for link budgets, atmospheric models, handovers, and concept of operations
Blue Book for low signal photon flux optical communications
Blue Book for high signal photon flux optical communications, especially intersatellite crosslinks

16. New Optical Communication Atmospheric Characterization Standards Required
Blue Book for real-time weather and atmospheric characterization data
The CCSDS WG should gather more information concerning the coordination and exchange of necessary atmospheric data, including collaborative effort, before finalizing the Blue Book

17. CCSDS Standardization Effort Estimate
Resources (mm= man months):
1 Green Book: 10mm
3 Blue Books: 90mm
Total: mm
Schedule:
Green Book for Link Budgets, etc: 1 yr
Low Photon Flux Blue Book: 2 yrs
High Photon Flux Blue Book: 4 yrs
Meteorological Data/forecast and handover: 4 yrs
Green Book – common link budgets
Blue book – low photon flux
Blue book – high photon flux
Blue book – meteorological data/forecast and handover
Complete
Begin
2014
2017
2018
2019
2015
2016

18. OLSG Recommended Standardization Schedule
2012
2013
2014
2015
2016
2017
2020
2025
CCSDS WG Apr 2014
Optical Terminal Development
Optical Terminal Flight
Standardization Development
OLSG Final Report
Jun 2012
OLSG Standardization Guidance Addendum
Jul-Nov 2012
Priority 1 Guidance for CCSDS:
Green Book for link budgets, atmospheric models, handovers, and concept of operations
Blue Book for low signal photon flux optical communications
Blue Book for high signal photon flux optical communications
Blue Book for real-time weather and atmospheric characterization data
IOAG-15b
Jun 2012
IOAG-16
Dec 2012
CCSDS BoF
Concept Paper and Charter
Oct 2013
IOP-3
June 2013
Technology Demonstrations
2012
2013
2014
2015
2016
2017
2020
2025
TerraSar-X (DLR)
2009 LEO-ground demo
1064 nm, Homodyne BPSK
OPALS (NASA)
ISS-ground demo
1553 nm, OOK modulation
LLCD (NASA)
2013 Moon-Earth demo
1550 nm, single photon detection and PPM
Sentinel/EDRS (ESA)
2014 ISL
1064 nm, Homodyne BPSK
LCRD (NASA)
2017 GEO-Ground and ISL LEO-GEO
1550 nm, direct detection PPM, and DTN
TDRS (NASA)
2025 GEO-Ground Operational Relay
1550 nm, DPSK and high speed routing
TerraSar-X to NFIRE (DLR)
2008 ISL LEO-LEO demo
1064 nm, Homodyne BPSK
OSIRIS (DLR-ICAN)
2014 LEO-Earth demo
1550 nm, IMDD
Optel-µ (ESA)
2017 LEO-Earth demo
direct detection and PPM
LCT-135/Alphasat (ESA)
2013 ISL, GEO to Earth demo
1064 nm, Homodyne BPSK
DOT (NASA)
2020 Mars-ground
1550nm, direct detection PPM
SOTA (NICT)
LEO to ground demo
1064 and 1550nm, OOK modulation

19. Optical Communications Eye Safety
OLSG was asked to establish contact with the International Civil Aviation Organization and work to ensure that the optical communications uplink budget in various scenarios (LEO, GEO, GEO Relay, Lunar, L1, L2, and Mars) were eye safe to maximum extent possible
OLSG discovered several barriers to complete eye safety for optical communications, including maximum permissible exposure (MPE) thresholds, irradiance at aperture, near field effects, and time spent in the beam, all of which factor into ICAO standards (also ANSI and IEC standard)
ICAO welcomes further dialogue and education on optical communications from all international agencies that will be utilizing this technology in the future to create an eye safe operational environment
It is recommended that IOAG develop a Liaison with ICAO for the purpose of minimizing restrictions on aviation eye safety rules to allow minimum impact of optical communication ground stations, yet ensuring an eye safe operational environment
Initial discussions begun with astronaut office responsible for eye safety and it is recommended that a continuing dialog take place with the objective of defining specific requirements for astronaut eye safety

20. IOP-3 Communique
The IOP-3 encourages the member agencies to prepare for optical communications as the next evolution of space communications; therefore:
1. The IOP recognizes the good work of the OLSG and the benefits of developing
interoperability in the domain of optical communications.
2. The IOP recommends that the member agencies begin preparing for future cross support
of space-Earth and space-space optical communications by developing interoperable
standards.
3. The IOAG is requested to provide guidance to CCSDS in the development of the required
4. The IOP urges collaboration on demonstrations, and experiments that may be useful in
the standardization and the development of optical communications technology.
5. The IOP member agencies are encouraged to share with other IOAG members their
technical and operational experience.
6. The IOP recommends assessing the results of the upcoming technology demo missions to
verify the feasibility of a common wavelength for a future intersatellite link in the context
of a data relay system in order to facilitate interoperability. This would be similar to the
concept of the Space Network Interoperability Panel (SNIP) approach.
7. The IOAG is requested to report progress in the optical communications cross support
area at IOP-4.