Constellations Tables

The few lines introducing this page are a modified copy of the Big LEOs page of Lloyd Wood [University of surrey]

This section summarises the GEO/MEO/LEOs in a tabulated form. The tables are a compilation of data from miscellaneous sources. When conflicting data entries were found, the most recent or reliable sources were used. As this information was compiled from a number of diverse sources, consistency between entries for the same system is not guaranteed, nor even aimed at. Figures for e.g. system cost may entail different elements for the different systems, and serve at best as a very rough indication only. These tables may nonetheless be usable for comparing the systems, provided that great care is taken in the comparison and differences in the systems are taken into account. Blank entries correspond to cases where no data was available at the time of compilation.

Be particularly careful when comparing the data with that for Iridium and Teledesic, as these two systems are very different in design from the others, thanks in part to their use of intersatellite links. Note also that Teledesic focuses on high-bandwith data while the Big LEOs focus on voice while supporting low-bit-rate data.

You can't draw conclusions from this table without knowing a lot about how the individual systems work, and comparisons between the networked and non-networked constellations can be particularly misleading, especially if you forget that Teledesic isn't really aimed at the mobile voice communications market.

Since this table was drawn up, development on Odyssey has stopped and Teledesic has undergone a redesign, details of which are not publically available. This is not reflected in the data presented here.

Information on the Ellipso [ELL96] and Constellation [CAS95] systems has been removed from this version of the tables. Although these constellations finally received their FCC licences on July 1 1997, the data available when these pages were compiled is particularly sketchy.

Informations on Skybridge is particularly rare. The date on this constellellation here is a compilation of different sources.

[JOH95] is one of the more comprehensive overviews of technical data for the Big LEOs, and contains many tables, also including link budget parameters. The data is however slightly dated; it reflects the situation as perceived at the beginning of 1994.

Lloyd Wood's pages for BIG LEOs satellites are good sources of informations [LLO98].

This paper present :


 Broadband Satellites

Used for data in general (ex : pure data, voice and video, multimedia, etc...)
 

Astrolink Celestri Cyberstar Spaceway Skybridge Teledesic

Service scheduled to

beginning 2001

End 2002

?

Early 2002

2002

2002

FCC licenced

?

?

?

?

yes

yes

Service Types

?

?

?

?

Voice, data, fax, paging, video

Voice, data, fax, paging, video

Satellie/Orbit

?

7/9

?

?

2 Constellations

8/4

24/12 near-polar

3 in orbit

Number of 
Satellites
9 63 leo + 9 geo 3 20 meo + 16 geo 80 288
Altitude (km) GEO 1400 (LEO) GEO 10352 (MEO) 1469 (LEO) 1350 (LEO)
Orbits Clarke Inclination leo : 
(7x48°, 1x0°)
Clarke  Inclination meo : 
( 4x55°, 1x0°)
? Inclination
12x98°
Intersatellite 
communication
Yes Yes

6

? Yes No

0

Yes

8

60GHz

Coverage concept

?

?

?

?

EFC

EFC

Backers Lockheed Martin Motorola Loral Hughes Alcatel, Loral Bill Gates, 
Craig Mc Caw, Boeing
User Terminal Cost $1000-$2500 $750+ $800(Ku) - $1000(Ka) -$1000 $500 N/A
System Cost (billions) $4 G $13 G $1.3 G $6.3 G $3.5 G $9 G
Access Method FDMA, TDMA FDMA, TDMA FDMA, TDMA FDMA, TDMA CDMA, TDMA
FDMA, WDMA
MF-TDMA, TDMA
Spectrum Ka Ka and 40-50 GHz Ku and Ka Ka Ku Ka
Antenna Size (cm) 40 60 80-120 25 66 ?
Data Throughput 9.6 Mbps 155 Mbps 400 Kbps (Ku) to 
30 Mbps (Ka)
6 Mbps Uplink : 16 Kbps-2Mbps 
Downlink : 
16 Kbps - 60 Mbps
16 Kbps - 64 Mbps 
 
Global Throughput 6 Gbps 1.5 Gbps 9 Gbps 4,4 Gbps ? 10 Gbps

Satellite-Ground Throughtput

?

64kpbs-2Mbps

10-16-51-155Mbps

?

?

?

155Mbps - 1.2 Gbps

Protocol/Routing/Packet format

?

ATM

17,5 Gbps

?

?

ATM

Proprietary/Connectionless adaptive/512bits packet

 


Personal Communications Systems

Used for voice, fax and messaging
 
 

Ecco Ellipso Globalstar Ico Iridium Odyssey Orbcomm

Service scheduled to

?

?

1999

2000

1998

2000

(Cancelled)

?

FCC licenced

?

?

yes

no

yes

yes

?

Number of 
Satellites
46 14 48 active

8 in-orbit spares

10 active

2 in-orbit spares

66 active

6 in-orbit spares

12 active

3 in-orbit spares

36

Service types

?

?

voice, data, fax, paging, short message service, position location

voice, data, fax, paging

voice, data, fax, paging, messaging, position location

voice, data, fax, paging, short message service, position location

?

Altitude (km) 2000 (LEO) 520 - 7846 (MEO) 
4223 - 7846 (MEO)
1414 (LEO) 10335

changed to 10390(MEO)

780 (LEO) 10355 (MEO) 781 (LEO)
Orbits Inclination  leo : 
( 7x62°, 1x0° )
Inclination  leo : 
( 2x116.6°, 1x0° )
Inclination leo : 
(8 x 52°)
Inclination  meo : 
( 2 x 45°)
Polar Orbits 
(6 x 86,5)
? ?
Satellites per Orbit 11 on equatorial
5 per inclined orbit
6 on equatorial
4 per inclined orbit
6 5 11 ?

?

Coverage concept

?

?

SFC

SFC

SFC

EFC

mechanic

?

Backers Constellation Communications Mobile Communcations Holdings Loral, Qualcomm, Alcatel , France Telecom Inmarsat, Hughes Space Telecom Motorola TRW, Teleglobe Orbital Sciences, Teleglobe, ...
User Terminal Cost ? $1000 $750 $100-300 $2500-$3000 $300 $500+
System Cost (billions) $ 3 G $ 0.75 G $2.5 G $4.5 G $ 3.7 G $ 1.8 G $ 0.33 G
Spectrum ? UHF L, S and C S and C L and Ka L, S and Ka VHF
Data Throughput ? 0.3-9.6 Kbps 7.2 Kbps 2.4 Kbps 2.4 Kbps 9.6 Kbps 56.7 Kbps