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This MITRE Technical Report presents an updated survey and evaluation of four
proposed systems that are intended to provide the full range of mobile satellite services
including voice, data, facsimile and position determination, in the 1 to 3 GHz band from
either low or medium Earth orbit. The current competitive climate in the MSS industry has
con...
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Future spacecraft will require a paradigm shift in the way the information is transmitted due to the continuous increase in the amount of data requiring space links. Current radiofrequency-based communication systems impose a bottleneck in the volume of data that can be transmitted back to Earth due to technological as well as regulatory reasons. F...
Citations
... The provision of an unobstructed line of sight between mobile user terminal and a satellite depends in turn on the possibility of high elevation angles. From [18][19], the results appeared to indicate that in order to achieve an availability comparable to that of well-developed cellular system, at least 95%, it would be necessary for single satellite systems to provide substantial margin at low elevation angles, or to modify the satellite constellations so that elevation angles above 40° . ...
... The provision of an unobstructed line of sight between mobile user terminal and a satellite depends in turn on the possibility of high elevation angles. From [18][19], the results appeared to indicate that in order to achieve an availability comparable to that of well-developed cellular system, at least 95%, it would be necessary for single satellite systems to provide substantial margin at low elevation angles, or to modify the satellite constellations so that elevation angles above 40° . ...
A system for global inventory control of electronically tagged military hardware is achievable using a LEO satellite constellation. An equipment Tag can communicate directly to the satellite with a power of 5 watts or less at a data rate of 2400 to 50,000 bps. As examples, two proposed commercial LEO systems, IRIDIUM and ORBCOMM, are both capable of providing global coverage but with dramatically different telecom capacities. Investigation of these two LEO systems as applied to the Tag scenario provides insight into satellite design trade-offs, constellation trade-offs and signal dynamics that effect the performance of a satellite-based global inventory control system.
The next generation of mobile satellite systems (MSS) will use the
constellation of satellites in non-geostationary orbits for global
communication, The proposed S-PCNs are Iridium, ICO, Globalstar, Odyssey
and Ellipso. The first two systems propose to use a time division
multiple access (TDMA) scheme and the others a code division multiple
access (CDMA) scheme. It is claimed that CDMA based S-PCNs can share the
allocated frequency bands due to the interference resistant property of
CDMA. In this paper, we present the results of the investigation on the
total system capacity achievable by totally overlapped band sharing
between the two systems such as Globalstar and Odyssey under perfect and
imperfect power control conditions. Results for a single satellite
system operating in a band segmentation approach are also presented for
comparison, again under perfect and imperfect power control
The demand for global telephony services for mobile users requires
the use of constellations of non-geostationary orbits. The proposed
S-PCNs are Iridium, Inmarsat-P, Globalstar, Odyssey and Ellipso. The
first two systems propose to use a time division multiple access (TDMA)
scheme and the others code division multiple access (CDMA) scheme. It is
claimed that CDMA based S-PCNs can share the allocated frequency bands
due to the interference resistant property of CDMA. Spectrum sharing
must be based on defined interference criteria being satisfied. The
interference events are based on the statistics of carrier to
interference ratio (C/I). For this a computer simulation was developed
to model the dynamic nature of any constellation, and produces all the
statistical values of C/I to a mobile in a fading channel. The
simulation includes constellations results of proposed S-PCNs with
multi-spotbeam antennas (MBA). We present the results of the
investigation on the effect of imperfect power control on the total
system capacity for a totally overlapped band sharing scenario. Results
for a band segmented scenario are also presented for comparison
As charged by Congress and the Office of the Secretary of Defense,
the Defense Information Systems Agency (DISA) created the Commercial
Satellite Communications Initiatives (CSCI) program. The CSCI program's
purpose is to assess the use of available and planned commercial
communications satellites to fulfill, in a cost-effective manner,
certain military communications that would be otherwise provided by
Government satellite systems. This paper describes planned commercial
satellite based personal communications systems (PCS) capable of
providing voice, data and other services anywhere in the world to mobile
users equipped with lightweight, handheld transceivers. The paper then
provides an overview of issues associated with military use of satellite
PCS services
