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All rights reserved, 2007, Thales Alenia Space

BS-SPI

September 2012

Templatereference:100182079N-EN

Broadband satellite communications in Ka band:

System approach and solutions

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Table of Contents

Ku band satelli tes in Kazakhstan: KazSat2 and KazSat3

Why Ka band:

Technical Opportunities of Ka-band: RF performance

Regulatory Opportunities of Ka-band: Available spectrum resources

Technical Opportunities of Ka-band: broadband satellite communications andnetworks

Fade Mitigation techniques for broadband satellite systems in Ka band

Capacity optimization in High Throughput Ka band Satellite Systems

Concluding remarks

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KazSat 2

KazSat 2

Launched in 2011

Satellite in geostationary orbit at 86.5E

Payload: manufactured by TAS

16 communications channels in Ku-

band with useful bandwidth of 54 MHz

U/L: 14.00 14.50 GHz D/L: 10.95 11.70 GHz

Spacecraft: Express MD from KHRUNICEV

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RF Performance vs. Frequency (2/2)

Ka band antenna directivi ty is higher

than that of comparably sized Ku

band antennas.

Antenna di rect ivi ty is a key

performance to dimension theSatellite Communication System.

3dB (satellite RX)Gain RX

3dB (satellite TX)Gain TX0,00

0,50

1,00

1,50

2,00

2,50

3,00

3,50

4,00

0 1 2 3 4 5 6

Antenna Diame ter (m)

3dBbeam

width(deg)

F = 12 GHz

F = 20 GHz

F = 30 GHz

Half-Power Beamwidth vs. Frequency, Antenna Size

BENEFITS

Ka band well suits to multi -spot coverage, providing high satellite EIRP and G/T

for Very High Throughput Satellite Systems.

Ka band improved directivi ty performance makes frequency coordination less

crit ical, especially for small terminals ( < 1 m) and small orbital separations.

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Why Ka band ?

Large allocated

frequency range

Fade Mitigation

RF performance

BroadbandCommunications

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Why Ka band ? RF Performance !

Large allocated

frequency range

Fade Mitigation

RF performance

Broadband

Communications

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RF Performance vs. Frequency (1/2)

Ka band antennas gain is higher

than that of comparably sized Ku

band antennas.

RX and TX antenna gains are key

RF performance to dimension theSatellite Communication System:

Gain RXG/T

Gain TXEIRP

Antenna Gain vs. Frequency, Antenna s ize

35,00

45,00

55,00

65,00

0 1 2 3 4 5

Antenna Diame ter (m)

Gain(dBi)

F = 12 GHz

F = 20 GHz

F = 30 GHz

BENEFIT

Ka band achievable satellite EIRP and G/T reduce the requi rements on EIRP and

G/T of ground traffic elements (gateway, satellite terminals)

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Why Ka band ? Frequency Spectrum !

Fade Mitigation

RF performance

BroadbandCommunicationsLarge allocated

frequency range

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Ka band Frequency Spectrum allocation

The allocated Ka band Frequency Spectrum is

wider than Ku band frequency spectrum

allocated to FSS:

2 GHz allocated to coordinated services (e.g.

Feeder Link, TX, RX):

[27.5 - 29.5] GHz, RX by satellite

[17.7 - 19.7] GHz, TX by satellite

500 MHz allocated to high EIRP satellite

terminals (HEST) with exemption from individual

licensing if using an EIRP not exceeding 60

dBW:


[19.7 - 20,2] GHz, TX by satellite 1 GHz allocated for exclusive use to satellite

services:


[20,2 - 21.2] GHz, TX by satellite

BENEFITS

An overall range of 3,5 GHz, which

largely increases by exploiting multi-

spot coverage with frequency reuse and

polarization discrimination.

27,5

GHz

29,5

GHz

30,0

GHz

31,0

GHz

17.7

GHz

19.7

GHz

20.2

GHz

21.2

GHz

U/L

D/L

Feeder Link User Link Exclusive Use

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Why Ka band? Broadband Communications!

Large allocated

frequency range

Fade Mitigation

RF performance


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Broadband Institut ional Communications

Two-WayBroadband

Broadband Internet Access

Virtual Private Network and Critical

Network Infrastructures for secure

data exchange

Video-Surveillance for monitoringand security purposes

Emergency Communication

Networks

Distance learning

Distance healthcare

Governmental Institutions

Hospitals, Medical Centers

Schools, Universities

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Broadband Business Communications

Satellite News

Gathering

Professional Internet Access

Intranet and VPN for secure data

exchange

Site interconnection

Machine to Machine Supervisory

Control And Data Acquisition

Internet Backhauling

Backup and Emergency Networks

Satellite News Gathering

Data Gathering

Enterprises

SoHo

News agencies

Enterprises

Professional

Data Network

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Broadcasting

and Content

Delivery

IPTV with push VoD

IP Multicast and Push platform

IP streaming/webcasting

Direct-To-Home TV

Digital Radio Broadcasting CD quality audio

Store-and-forward

Video-on demand

Web-casting

High throughput Internet

Consumers

Consumers

Two-Way

Broadband

Consumer Communication Services

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From Communication Needs to Connectivity

Communication Needs Communication Connectivity

User Family Communication ServicesApplications CommunicationConnectivity

Internet Access Star

Webcasting and Streaming Star

IPTV with push VoD Star

IP Multicast and Push platform Star

Direct-To-Home Television service Star

High quality audio Star

Video-on demand Star

Broadband Internet Access Star Site Interconnection MeshIntranet and VPN with secure data exchange MeshMachine to Machine Supervisory Control / Data MeshSatellite News Gathering Star

Broadband Internet Access Star

VPN and CNI with secure data exchange Mesh

Emergency Communication Networks Star / Mesh

Back up and Disaster Recovery Networks Star

Distance learning MeshDistance Healthcare Star / Mesh

Corporate, Business

Governmental, Institutions

Consumer

A synergic Mesh and Star

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A synergic Mesh and Star

Satellite Communication System

To/From

External Networks

Control of

Mesh and Star

Interco to

external nets

Management

System

Monitoring

Sensors

NCC/GTW

LAN

LAN

Terminal

HubTerminal

Terminal

User Link

License Exempt

Ka Band

Feeder Link

Coordinated

Ka Band

U/L

D/L

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Why Ka band? Fading Countermeasures!

Large allocated

frequency range

Fade Mitigation

RF performance


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Kazakhstan rain intensity statist ics

ASTANA

KARAGANDA

ALMATYAKTAU

AKTOBE

35

30

25

20

15

10+40 +45 +50 +55 +60 +65 +70 +75 +85+80 +90

+40

+45

+50

+55

+60

+35

ASTANA

KARAGANDA

ALMATYAKTAU

AKTOBE

ASTANA

KARAGANDA

ALMATYAKTAU

AKTOBE

ASTANA

KARAGANDA

ALMATYAKTAU

AKTOBE

35

30

25

20

15

10+40 +45 +50 +55 +60 +65 +70 +75 +85+80 +90

+40

+45

+50

+55

+60

+35

Rain Intensity (mm/h) exceeded during 0.01% ( 52 min.) of an average year

Fade durations statistics vs frequency

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Fade durations statistics vs. frequencyaccording to ITU-R P.1623-1

0,5

10,5

20,5

30,5

40,5

50,5

60,5

70,5

80,5

90,5

1 10 100 1000 10000

Fade Duration D (sec)

ExceedanceP

robability(%)

f = 12 GHz

f = 20 GHz

f = 30 GHz

CDF of total fraction of fade time due to fades of duration longer than D

(example for elevation = 25, fade attenuation > 8 dB)

For a given attenuation, the

probability of long fades (duration >

15 min) increases with frequency.

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System Fade Mitigation Techniques (1/2)

Fade Mitigation Techniques aim at adapting the operating conditions

(modulation, coding and power level) of the ground segment traffic elements

(gateways, satellite terminals), so that the System performance is no longer

dominated by the worst-case link condi tions, but rather by the average link

conditions of the system.

Thus, deep fading events have a lower impact on the overall system capacity

and cause the reduction of the individual l ink peak data rates only.

Ka band Broadband Satellite Systems take advantage of a combination of the

following Fade Mitigation Techniques:

Adaptive Coding And Modulation (ACM);

Adaptive Coding (AC);

Dynamic Rate Adaptation (DRA); Uplink Power Control (UPC).

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System Fade Mitigation Techniques (2/2)

Uplink Power Control (UPC):

The terminals and gateways increase the transmit power, with mitigation capability ranging from few toseveral dBs.

UPC applicable to compensate for uplink fades only.

Adaptive Coding And Modulation (ACM):

the MODCODE, i.e. the combination of modulation type and forward error correction code, of each terminalis adaptively tuned to meet the current terminal requirements, determined by channel conditions.

The goal of adaptation is to give each terminal the highest possible data rate that the link may support, whilepreserving operating margin enough to compensate short term fluctuations.

Terminals in the same beam may use different MODCODE values, because rain fades tend to be highlylocalized.

Adaptive Coding (AC):

the CODE, i.e. the forward error correction code rate, of each terminal is adaptively tuned keeping constantthe modulation type, to meet the current terminal requirements, determined by channel conditions changes.

The goal of adaptation is to give each terminal the highest possible data rate that the link may support, whilepreserving operating margin enough to compensate short term fluctuations.

Terminals in the same beam may use different CODE values, because rain fades tend to be highly localized.

Dynamic Rate Adaptation (DRA):

the Symbol Rate of each terminal is adaptively tuned to meet the current terminal requirements, determinedby channel conditions changes.

The goal of adaptation is to give each terminal the highest possible Symbol Rate that the link may support,while preserving operating margin enough to compensate short term fluctuations.

Terminals in the same beam may use different Symbol Rate values, because rain fades tend to be highlylocalized in space.

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Combined Fade Mitigation Techniques

ACM and UPC aim at counteract ing the l ink fading by adapting the data rate and TX power

as follows:

UPC increases the TX power to mitigate/compensate the fade attenuation and bring the SNR back to

a level that possibly keeps the MODCOD unchanged and, so, the data rate;

when the maximum UPC compensation range is reached, the residual SNR reduction due to fading is

counteracted by means of ACM, which changes the MODCOD to reduce the data rate down to the

level that matches the link conditions;

ACM and UPC do not change the communication symbol rate.

AC+DRA counteract l ink fades by adapting the data rate and the symbol rate as fo llows:

AC reduces the TX data rate to mitigate/compensate the fade attenuation and bring the SNR back to

a level that possibly keeps the MODCOD unchanged and, so, the data rate;

AC does not changes the symbol rate;

when the maximum AC compensation range is reached, the residual SNR reduction due to fading iscounteracted by means of DRA, which reduces the communication symbol rate;

Accordingly, the terminal moves to a smaller carrier.

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The ACM System Control Loop

The Down Threshold and the Up Thresholdare defined considering: an ACM margin due to the system loop delay and

latency:

loop delay counts for the overall end to endcontrol process, including signalingtransmission, propagation and processing; onthe average it is in the order of 2 s;

rain fade slope in the range of 0.51 dB/s fortypical availability performance;

the resulting ACM margin is in the range of 12dB.

modem implementation losses;

hysteresis margin, defined to avoid transitions whenthe fading fluctuates around a threshold point.

CDF of fade slope (Cut-off freq. = 0,02 Hz, Delta t = 2 s)

0

0,2

0,4

0,6

0,81

1,2

1,4

1,6

1,8

2

2,2

2,4

2,6

0,001 0,01 0,1 1 10 100

Fade slope (dB/s)

Percentageoftime(%)

A = 1 dB

A = 8 dB

A = 10 dB

A = 15 dB

A = 20 dB

ACM, as DRA and AC, is a threshold based mechanism for the decision of the

MODCOD to be used, given a fading condition in a communication configuration

characterized by system specific target data rate and RF performance of space

segment and ground t raffic segment elements.

Thresholds are defined based on the Satellite System operational scenario (link

budgets) and on the performance of ground traffic elements.

f C ( / )

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Example of ACM control loop (1/2)

Date

-3,0

-2,0

-1,0

0,0

1,0

2,0

3,0

4,0

5,0

6,0

7,0

8,0

9,0

10,0

11,0

12,0

13,0

14,0

0,40 0,80 1,20 1,60 2,00 2,40 2,80 3,20 3,60

Es/N0

Spectral Efficency

Theoric Threshold

2/3

1/2

2/5

3/5

2/3

1/4

4/5

3/4

8/9

5/6

3/4

2/3

Q PSK 8 PSK 16 APSK

E l f ACM t l l (2/2)

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Example of ACM control loop (2/2)

Date

O ti i ti f K b d S t llit S t

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Optimization of Ka band Satellite Systems

Under uniform weather, terminal type and traff ictargets over a service area: A set of MODCOD values are used over the overall

service area;

Each MODCOD value suits to an area over which therange of System RF performance (EIRP, G/T)determines a signal to noise ratio that is best satisfiedby the selected MODCOD; as an example:

MODCOD1: from CoC to EoC1; MODCOD2: from EoC1 to EoC3;

MODCOD3: from EoC3 to EoC5.

Non-uniform MODCOD allocations in a sector of asatellite beam result from: Co-existence of terminals with different RF performance

and data rate targets, requiring specific and differentMODCOD values;

Effects of localised fades, requiring different MODCODvalues even for same terminal types in different areas.

CoC EoC1

EoC3

EoC5

CoC EoC1

EoC3

EoC5

A wedding cake model well represents the allocation of MODCOD over a service area.

BENEFIT

This opt imizes Capacity and Availability over the service area.

C l di k

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September 2012

Concluding remarks

Ka band Systems are a win-win solut ion for HighThroughput Satellite Communications:

Improved RF performance vs. lower band FSS satellite systems

Larger frequency spectrum available

Excellent suitability to broadband communications, covering the

needs of all end user types, from residential to Institutions and

Governmental Bodies.

Consolidated base of space and ground segment products: large portfolio of high performance and flexible repeater

equipments and satellite antennas;

large portfolio of End-User terminal types, covering all

market segments and featuring small sizes, high

performance, installation easiness and high reliability

solutions for ground mission products, including: Payload

Traffic Manager, Communication Spectrum Monitoring,

Station Monitoring & Control for complete management of

space and ground elements.

High immunity to the effects of atmospheric conditions, thanks

to fade mitigation techniques, already implemented by ground

traffic element manufacturers and available for System

exploitation towards optimal performance in terms of traffic

capacity and communication availability.

Large allocated

frequency range

Fade Mitigation

RF performance


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