All rights reserved, 2007, Thales Alenia Space
BS-SPI
September 2012
Template reference : 100182079N
-EN
Broadband satellite communications in Ka band: System approach and solutions
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 2
September 2012
Table of Contents
Ku band satellites 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 and
networks Fade Mitigation techniques for broadband satellite systems in Ka band Capacity optimization in High Throughput Ka band Satellite Systems Concluding remarks
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 3
September 2012
KazSat 2
KazSat 2
Launched in 2011 Satellite in geostationary orbit at 86.5°E
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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 4
September 2012
RF Performance vs. Frequency (2/2)
Ka band antenna directivity is higher than that of comparably sized Ku band antennas. Antenna directivity is a key performance to dimension the Satellite Communication System.
θ3dB (satellite RX) ⇒ Gain RX θ3dB (satellite TX) ⇒ Gain TX
0,00
0,50
1,00
1,50
2,00
2,50
3,00
3,50
4,00
0 1 2 3 4 5 6
Antenna Diameter (m)
3dB
beam
widt
h (d
eg)
F = 12 GHzF = 20 GHzF = 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 directivity performance makes frequency coordination less critical, especially for small terminals (∅ < 1 m) and small orbital separations.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 5
September 2012
Why Ka band ?
Large allocated
frequency range
Fade Mitigation
RF performance
Broadband Communications
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 6
September 2012
Why Ka band ? RF Performance !
Large allocated
frequency range
Fade Mitigation
RF performance
Broadband Communications
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 7
September 2012
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 the Satellite Communication System:
Gain RX ⇒ G/T Gain TX ⇒ EIRP
Antenna Gain vs. Frequency, Antenna size
35,00
45,00
55,00
65,00
0 1 2 3 4 5
Antenna Diameter (m)
Gai
n (d
Bi)
F = 12 GHzF = 20 GHzF = 30 GHz
BENEFIT Ka band achievable satellite EIRP and G/T reduce the requirements on EIRP and
G/T of ground traffic elements (gateway, satellite terminals)
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 8
September 2012
Why Ka band ? Frequency Spectrum !
Fade Mitigation
RF performance
Broadband Communications
Large allocated
frequency range
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 9
September 2012
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:
[29.5 - 30.0] GHz, RX by satellite [19.7 - 20,2] GHz, TX by satellite
1 GHz allocated for exclusive use to satellite services:
[30.0 - 31.0] GHz, RX by satellite [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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 10
September 2012
Why Ka band? Broadband Communications!
Large allocated
frequency range
Fade Mitigation
RF performance
Broadband Communications
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 11
September 2012
Broadband Institutional Communications
Two-Way Broadband
Broadband Internet Access Virtual Private Network and Critical
Network Infrastructures for secure data exchange
Video-Surveillance for monitoring and security purposes
Emergency Communication Networks
Distance learning Distance healthcare
Governmental Institutions Hospitals, Medical Centers Schools, Universities
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 12
September 2012
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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 13
September 2012
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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 14
September 2012
From Communication Needs to Connectivity
Communication Needs Communication Connectivity
User Family Communication ServicesApplications
CommunicationConnectivity
Internet Access StarWebcasting and Streaming StarIPTV with push VoD StarIP Multicast and Push platform StarDirect-To-Home Television service StarHigh quality audio StarVideo-on demand StarBroadband Internet Access StarSite Interconnection MeshIntranet and VPN with secure data exchange MeshMachine to Machine Supervisory Control / Data MeshSatellite News Gathering StarBroadband Internet Access StarVPN and CNI with secure data exchange MeshEmergency Communication Networks Star / MeshBack up and Disaster Recovery Networks StarDistance learning MeshDistance Healthcare Star / Mesh
Corporate, Business
Governmental, Institutions
Consumer
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 15
September 2012
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
Hub Terminal
Terminal
User Link
License Exempt Ka Band
Feeder Link
Coordinated Ka Band
U/L
D/L
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 16
September 2012
Why Ka band? Fading Countermeasures!
Large allocated
frequency range
Fade Mitigation
RF performance
Broadband Communications
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 17
September 2012
Kazakhstan rain intensity statistics
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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 18
September 2012
Fade durations statistics vs. frequency according 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)
Exce
edan
ce P
roba
bilit
y (%
)
f = 12 GHzf = 20 GHzf = 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.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 19
September 2012
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 conditions, 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 link 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).
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 20
September 2012
System Fade Mitigation Techniques (2/2)
Uplink Power Control (UPC): The terminals and gateways increase the transmit power, with mitigation capability ranging from few to
several 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 terminal is 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, while preserving operating margin enough to compensate short term fluctuations.
Terminals in the same beam may use different MODCODE values, because rain fades tend to be highly localized.
Adaptive Coding (AC): the CODE, i.e. the forward error correction code rate, of each terminal is adaptively tuned keeping constant
the 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, while
preserving 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, determined by 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 highly localized in space.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 21
September 2012
Combined Fade Mitigation Techniques
ACM and UPC aim at counteracting the link 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 link fades by adapting the data rate and the symbol rate as follows:
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 is
counteracted by means of DRA, which reduces the communication symbol rate; Accordingly, the terminal “moves” to a smaller carrier.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 22
September 2012
The ACM System Control Loop
The “Down Threshold” and the “Up Threshold” are defined considering: an ACM margin due to the system loop delay and
latency: loop delay counts for the overall end to end
control process, including signaling transmission, propagation and processing; on the average it is in the order of 2 s;
rain fade slope in the range of 0.5÷1 dB/s for typical availability performance;
the resulting ACM margin is in the range of 1÷2 dB.
modem implementation losses; hysteresis margin, defined to avoid transitions when
the fading fluctuates around a threshold point.
CDF of fade slope (Cut-off freq. = 0,02 Hz, Delta t = 2 s)
00,20,40,60,8
11,21,41,61,8
22,22,42,6
0,001 0,01 0,1 1 10 100
Fade slope (dB/s)
Perc
enta
ge o
f tim
e (%
)
A = 1 dBA = 8 dBA = 10 dBA = 15 dBA = 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 traffic segment elements.
Thresholds are defined based on the Satellite System operational scenario (link budgets) and on the performance of ground traffic elements.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 23
September 2012
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/N
0
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
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 24
September 2012
Example of ACM control loop (2/2)
Date
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 25
September 2012
Optimization of Ka band Satellite Systems
Under uniform weather, terminal type and traffic targets 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 the
range of System RF performance (EIRP, G/T) determines a signal to noise ratio that is best satisfied by 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 a satellite beam result from: Co-existence of terminals with different RF performance
and data rate targets, requiring specific and different MODCOD values;
Effects of localised fades, requiring different MODCOD values 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 optimizes Capacity and Availability over the service area.
All rights reserved, 2007, Thales Alenia Space
BS-SPI
Page 26
September 2012
Concluding remarks
Ka band Systems are a win-win solution for High Throughput 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
Broadband Communications