Co-existence of GSO and NGSO HTS systems : …proceedings.kaconf.org/papers/2017/clq/4_2.pdf-...

ESA UNCLASSIFIED - For Official Use

Co-existence of GSO and NGSO HTS systems :

technical considerations

Damien ROQUES

16/10/2017

ESA UNCLASSIFIED - For Official Use Roques, Damien | 02/10/2017 | Slide 2

Broadband systems in FSS bands - GSO (geostationary) “GEO-HTS” systems :

- HTS, multi-beam systems in Ku and Ka band

- 3 Millions consumers worldwide (Euroconsult)

- Example : Eutelsat Ka-Sat, Intelsat Epic, Echostar, Viasat…

- Upcoming NGSO (non-geostationary) “LEO-HTS” broadband systems :

- Constellations of 10s, 100s, 1000s of satellites

- At various stages of maturity

- ESA supports NGSO SATCOM constellations through its ARTES programme, and in particular addresses interference and regulation issues

Summary of broadband systems filed to the FCC in Ku/Ka band in Nov. 2016

ONEWEB TELESAT LEOSAT SPACEX O3B BOEING KEPLER VIASAT SPACE NORWAY

NB Satellites (total) 720 117 108 4425 60 60 140 24 2

Orbit TYPE LEO LEO LEO LEO MEO >25000 kms LEO MEO HEO

Band Ku/Ka Ka Ka Ku/Ka Ka Ka Ku Ka Ku/Ka


ESA scope of activities

- Sharing frequency resource among broadband systems :

- is an issue of high technical complexity, involving sophisticated regulations

- requires the elaboration of adequate technical solutions

- Under ARTES Future Preparation, part of effort focused on NGSO Interference and Regulations :

• Investigate the issue of Interference between NGSOs and GSOs, as well as between different NGSOs hypothetically sharing the same bands

• Investigate interference mitigation techniques and analyse their impact on the system throughput

• In order to achieve such objectives, an End to End software simulator for assessing performances of Mega Constellations was developed internally.


How can systems work technically ?

Coordination between GSO systems: - Static geometry - Based on “long term” interference ITU Reco. S.1323 : ∆𝑇

𝑇< 6%

GEO


How can systems work technically ?

Coordination with NGSO systems - Dynamic geometry - based on “short term” interference

ITU Reco. S.1323 :

𝑎𝑣𝑎𝑣𝑣𝑎𝑣𝑣𝑣𝑣𝑣𝑣 𝑑𝑑𝑑𝑑𝑎𝑑𝑎𝑣𝑣𝑑𝑑 𝑐𝑑𝑐𝑣𝑑𝑑 𝑓𝑑𝑑𝑐 𝑁𝑁𝑁𝑁 𝑠𝑣𝑠𝑣𝑑𝑐𝑠 < 10 %

EPFD limits to respect

- Case # 1 : NGSO / GSO coordination - NGSO GSO EPFD Limits (uplink and downlink) protecting GSO arc

?

- Case # 2 : NGSO / NGSO coordination No framework derived from recommendation

No regulation protection

- GSO NGSO NGSO systems are not protected by regulation


LEOSIM :


LEOSIM System simulator : Interference analysis module

Objective :

• quantification of impact : • of NGSO system EPFD limit levels • of GSO systems interferences on NGSO services

• impact on NGSO mission (capacity / coverage)

Impac

t of

inte

rfer

ence

on t

raffic

with a

nd

withou

t m

itig

atio

n t

echniq

ues

NGSO – GSO interference NGSO – NGSO Interference

Objective :

• estimation of frequency of interference events

• simulation of mitigation techniques • impact on NGSO mission (capacity / coverage)

Min

imum

sep

arat

ion a

ngle

in d

egre

es,

for

a giv

en inst

ant

of t

ime,

bet

wee

n 2

con

stel

lation

s


How can systems work technically

Key interrogations :

- Case #1 : NGSO – GSO coordination : - Interference from NGSO into GSO :

- Respect of EPFD limits ?

- Interference from GSO into NGSO : - Service availability without regulation

protection ?

- Case #2 : NGSO – NGSO coordination

- Best way to coordinate under current regulation ?


Case #1 : NGSO - GSO coordination

- Questions raised :

- Can new systems, with hundreds of satellite, adapt to current regulations ?

- What are the constraints involved, and the potential losses of capacity / coverage ?

- Simulations realised :

- On a constellation typ. involving hundreds of satellites, with static coverage

- Assessment of EPFD downlink statistic over Earth

- Investigation of mitigation technique for reaching ITU’s EPFD requirements

- Assessment of potential impact on NGSO system service, taking into account realistic user distribution

- Assessment of impact, from the emissions of GSO systems into the NGSO.


Results of the GSO/NGSO simulation realised

- Current EPFD limits are met with mitigation techniques

• Some marginal non compliance in our (not optimised) simulation

• Mitigation techniques involve realisable operations

- Impact on overall system capacity is limited

• Maintain of a global coverage • Overall throughput difference

rather small • Interference fom GSO into NGSO

needs to be taken into account

-200 -195 -190 -185 -180 -175 -170 -165 -160 -155 -150

epfd Down [dBW/m2 /40kHz]

10 -6

10 -5

10 -4

10 -3

10 -2

10 -1

10 0

Prob

abilit

y th

at E

PFD

is ex

ceed

ed

EPFD Downlink UT 60 cm

ARTICLE 22 Mask

Results - all locations

Results - WCG

Results - LEOSIM Worst Case


Case #2 : NGSO – NGSO coordination

- Recall : reco S.1323 : maximum availability degradation from NGSO system interference shall not exceed 10%

- FCC has proposed a methodology, based on taking into account in-line events :

- an in line event happens when 2 satellites get physically aligned from a user location point of view, i.e. the angle difference becomes too small to separate them

- Main questions :

- What is the size of the angle ?

- What is the rule applied when an in line event occurs ?

- What needs to be shared between operators to compute in line events ?

Angle difference 1

1 : See FCC notice of proposed rulemaking, DA # 16-170


minimum angle separation seen on ground between 2 different constellations

LEOSIM SAMPLE OUTPUTS NGSO/NGSO Coordination

Uncoordinated operations Coordinated operations Conclusions - Without sufficient sharing of information, evaluation of interference events is quite pessimistic - Size of the separation angle needs to be carefully determined - In coordinated operations, mutual level of interference is mitigated and impact on capacity (on a global

scale) is limited.


LEOSIM – NGSO/NGSO coordination comparison of different angles for in-line events

Minimum angle = 10 degrees Minimum angle = 5 degrees Trigger based on ∆T/T

Visualisation of percentage of satellites involved in in-line events, depending on angle defined


Conclusions

- NGSO systems coordination is a major challenge, to address for an efficient use of spectrum bandwidth

- ESA presented a fully functional system SW for interference analysis - Estimation of interference and mitigation techniques - Analysis of consequences on the service

- First results are promising, although a lot of work remaining

- Interference framework towards GSO systems can be respected - Promising leads shall be investigated for NGSO-NGSO coordination


Next steps - Future enhancements of developed simulator

- Uplink computations - Integration of steerable beams for capacity computing

- Industry oriented activities initiated

• ARTES 3A.087 : Simulator for Managing Interference Between NGSO Constellations and GSO • Initiated : See EMITS AO 8919 • To validate our results, add new functionalities, enhance performances

• ARTES 3A.095 : Flexible resource allocation techniques for NGSO constellations

• pending approval - to be initiated in 2018

- ESA welcomes any feedback from interested parties ! - Contacts :

• Emiliano RE ([email protected]) • Damien ROQUES ([email protected])

Slide Number 1Broadband systems in FSS bandsESA scope of activitiesHow can systems work technically ?How can systems work technically ?Slide Number 6LEOSIM System simulator : Interference analysis moduleHow can systems work technicallyCase #1 : NGSO - GSO coordinationResults of the GSO/NGSO simulation realisedCase #2 : NGSO – NGSO coordinationSlide Number 12LEOSIM – NGSO/NGSO coordination�comparison of different angles for in-line eventsConclusionsNext steps

Co-existence of GSO and NGSO HTS systems : …proceedings.kaconf.org/papers/2017/clq/4_2.pdf-...

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