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.