Post on 27-Mar-2015
USING THE NEW L BAND MSS ALLOCATIONS
- Study Group 8 Seminar on Tomorrow’s Technological
Innovations Geneva, 9 September 2004
Marcus Vilaça
Manager, Systems Engineering
Advanced Systems Division
Inmarsat Background
• Established in 1979 as an international co-operative
• Privatised in April 1999
• Owns and operates 9 satellites : 4 x Inmarsat 2 5 x Inmarsat 3
• Contract for 3 x Inmarsat 4 satellites signed in May 2000
• Firmly established in maritime, aeronautical and land markets
• Customer base of over 320,000 users
• Current services include messaging, voice and data
• Global presence & network of suppliers of services and equipment
• GMDSS
Inmarsat 1st Generation Space SegmentMarecs Marisat
33 dBW EIRP 30 dBW EIRP
2 x 5 MHz bandwidth 2 x 5 MHz bandwidth
580 kg dry mass 360 kg dry mass
13.5 m solar array 2.2 m (w) x 3.8 m (h)
Launch : A – 20/12/81 (22/08/96) Launch : 1 – 19/02/76
B – 09/09/82 (F) 2 – 10/06/76
B2 – 10/11/84 (23/01/02) 3 – 14/10/76
Inmarsat 2
39 dBW EIRP
2 x 20 MHz Processed Bandwidth
700kg Dry Mass
14.5 m Solar Array Span
Launch: F1 – 30/10/90
F2 – 08/03/91
F3 – 16/12/91
F4 – 15/04/92
Inmarsat 3
49 dBW EIRP
2 x 60 MHz Processed Bandwidth
1000kg Dry Mass
20.5 m Solar Array Span
Launch: F1 – 03/04/96
F2 – 06/09/96
F3 – 18/12/96
F4 – 03/06/97
F5 – 04/02/98
Inmarsat 467 dBW EIRP
10 dB/K G/T
2 x 126 MHz Processed Bandwidth
9 m deployable reflector
3000 kg Dry Mass
6000 kg Launch Mass
12 kW spacecraft power
10 kW payload power
48 m Solar Array Span
Astrium’s Eurostar 3000 bus
Major Subcontractors
• TRW Astro
• EMS
• Alcatel
• Boeing
Launch : F1 – February 2005
F2 – July 2005
Inmarsat 4 Characteristics
• Frequency Bands• Mobile Link @ L Band and Feeder Link @ C band
• Transponders• Transparent bent-pipe, C/L, L/C, L/L, C/C & Navigational
• Digital Channeliser/Beamformer• 630 x 200 kHz channels, dynamically allocated to beams
• 256 beams
• Mobile Link (RHCP, digital beam former)• 228 narrow spot beams for BGAN service (1.1 degree grid)
• 19 wide spot beams for E&E service (4.05 degree grid)
• 1 global beam
• Feeder Link (RHCP & LHCP)• 1 global beam, dual polarisation
Inmarsat 4 Coverage
The MSS L Band Extension
Before WRC-031626,5 1660,5 1668 1675 1690 1710
Region 1Region 2 MSS Earth-to-space MSS Earth-to-spaceRegion 3
1492 1518 1525 1559 MHzR1R2 MSS Space-to-Earth MSS Space-to-EarthR3
After WRC-031626,5 1660,5 1668 1675 1690 1710
R1 MSSR2 MSS Earth-to-space Earth-to-R3 space
1492 1518 1525 1559 MHzR1 MSSR2 Space-to MSS Space-to-EarthR3 Earth
Classical band
L-Band Extension
Amethyst Programme
• Part of the ESA’s Artes 3 Line 4 study programme
• Feasibility study focused on the changes required to the I4 payload design, to enable utilisation of the L band extension
• Study lead by Astrium, supported by Inmarsat
• Scenario 1 : Modification of I4 flight model 3 (“FM3”)
• 1A - Minimum Changes
• 1B - New DSP
• Scenario 2 : Procurement a fourth spacecraft (“FM4”)
• 2A - New DSP
• 2B - Enhanced SSPA’s
• Main Outputs: Design Solutions, ROM Cost & Development Plan
I4 Payload Block Diagram
C-Band Rx Horn Rx
L-Band Rx / Tx Feed Array
L-Band Rx / Tx
Reflector
120
C-Band Payload Receive Section
Mobile to
Feeder
Feeder to Mobile
Forward Processor
Mobile
to Mobile
Postprocessor & L-Band Payload Transmit Section
DSP
Return Processor
C-Band Up-
Converter
C-Band Down-
Converter
Navigational Payload
Centralised Frequency Generator
LOs
C to L Integrity Checking
Pilot Tone Injection
Unit
To C-Band Downlink section
150
150 C-Band Payload Transmit Section
2
10
10
2
Automatic Level Control
2 120
120
C-Band Tx Horn Tx
4
2
C-Band to
C-Band
4 Preprocessor & L-Band Payload Receive Section
Nav L-Band Tx Antennas
L1
L5
I4 Frequency Plan
Baseline I4 L Band Pre-processor & DSP
1525 15591518 1626.5 1660.5 1668 1675Downlink Uplink
27 MHz BW 29 MHz BW
Extent of sliding window Extent of sliding window
ADC/DAC Bandwidth window can be placed anywhere within L-band spectrum, due to tuneable LOs
SAW Filter BW
ADC/DAC BW
Scenario 1 - L Band Pre-processor & DSP Changes
1525 15591518 1626.5 1660.5 1668 1675Downlink Uplink
15451646.5
27 MHz BW 27+ MHz BW
Extent of sliding window
Extent of sliding window
TBD
Tx b
and
reduced
(2 MH
z TB
C)
in order to
ob
tain
good
reje
ction
a
t Rx ba
nd freq
uencie
s
SAW Filter BW
ADC/DAC BW
Scenario 1 – Other Equipment Changes
• L Band Feed
• New diplexers
• Feed element retuning
• ONet’s
• New output filters
Scenario 2 - L Band Pre-processor & DSP Changes
1525 15591518 1626.5 1660.5 1668 1675
Downlink Uplink
TBD
41 MHz BW 41 MHz BW
48.5 MHz BW
Variant A
Bandwidths shown are ADC/DAC capabilities. These can be reduced by analogue filtering
Possible notch filtering
48.5 MHz BWVariant B
Scenario 2 – Other Equipment Changes
• L Band Feed
• New diplexers
• Feed element retuning
• ONet’s
• New output filters
• New SSPA’s
• Increased output power
Summary of Spectrum Issues
“Hard bounds” (extract from table 21-4 of Article S21 of ITU Radio Regulations)
PFD limits (dbW/m²)
as function of the angle of arrival (d)
reference
bandwidth
US territory in Region 2 between
the longitudes 71°W and 125°W
pfd < -181 0<d<4°
pfd < -193 + 20 log d 4°<d<20°
pfd < -213.3 + 35.6 log d 20°<d<60°
pfd < -150 60°<d<90°
4 kHz
other US territory in Region 2 pfd < -155 0<d<43.4°
pfd < -213.3 + 35.6 log d 43.4°<d<60°
pfd < -150 60°<d<90°
4 kHz
“Soft bounds” (coordination thresholds derived from table 5-2 of App 5 of ITU RR) PFD limits (dbW/m²)
as function of the angle of arrival (d)
reference
bandwidth
worldwide pfd < -146 0<d<5°
pfd < -148.5 + 0.5 d 5°<d<25°
pfd < -136 25°<d<90°
4 kHz
worldwide pfd < -128 0<d<5°
pfd < -130.5 + 0.5 d 5°<d<25°
pfd < -118 25°<d<90°
1 MHz
Territory of Japan pfd < -150 for all angles 4 kHz
Territory of Administrations listed
in S5.342
pfd < -140 for all angles 4 kHz
Territory of New Zealand pfd < -138 0<d<5°
pfd < -141.25 + 0.65 d 5°<d<25°
pfd < -125 25°<d<90°
1 MHz
Planned Spectrum Activities
• Studies into the use of the new bands and related sharing studies
• Participation in the work being carried out by WP8D.
• Regulatory study of the new bands
• Assess the use of the new bands by existing terrestrial services, and the possibility of utilization of those bands for the provision of MSS in various countries, concentrating in Region 1 and Region 3.
• Satellite antenna discrimination
• Analyse the impact of PFD limits on the service coverage area by taking into account satellite antenna discrimination performance.
Conclusion
• The MSS L Band extensions offer a great opportunity to significantly increase the capacity of MSS satellites.
• The modifications required to the baseline Inmarsat 4 satellites to allow service provision in the new bands are significant, but can be kept within limits that allow reduced risk and lower cost and schedule impact.
• A comprehensive study on the utilisation of the extended L band by existing services will be carried out, to provide an accurate picture of the current situation and of any possible constraints.