Ministry for
Communications
METHODOLOGY FOR MEASURING THE GEO
EXPLOITATION
ITU-R Workshop on
the Efficient Use of the Spectrum/Orbit Resource
Republic of Colombia
Joaquin G. Restrepo
Coordinator
International Affairs Office
Ministry of Communications, Colombia
Geneva, Switzerland, May 6th 2009
Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
GEO ATTRIBUTES
Natural Resource: it is determined by laws of the nature, being
humanity’s patrimony.
Not renewable: GEO results from a unique combination of orbit
parameters, and its artificial reproduction is beyond the human
capacities.
Scarce: a minimum angular separation among GEO satellites is
required when they share Bands of Frequencies and cover the
same or adjacent regions; therefore, the number of satellites
that can be located at the GEO is limited.
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
GEO EXPLOITATION
GEO exploitation must take into account the above attributes; hence it
should be addressed by the following principles (Art. 44 of ITU Constitution,
and Res. 80 of ITU Radio Rules):
1.Rationality
2.Efficiency
3.Economic
4.Equitable access to countries or groups of countries
5.Special needs of the developing countries
6.Geographical situation of particular countries.
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
OSR COMPONENTS
The Spectrum-Orbit Resource OSR is a set of
Frequencies, Coverage Areas, and Orbital Position
needed for the operation of any satellite communication
system.
This proposal deals with Fixed Satellite Services (Fixed
Satellite Services, FSS), operating from geostationary
orbit, GEO, also extendible to Broadcasting Satellite
Services, BSS
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
OSR COMPONENTS
 1. Orbital parameters: GEO is circular, equatorial, at 35,786 km; the only
parameter is position into GEO, as a coordinate of Longitude (°), East (E, +)
or West (W, -). Latitude is not required (equatorial latitude is 0.0 °)
 2. Frequency Plan: Bands of Frequencies to be used, and within each
band the channels, both earth to space (uplink) and space to earth
(downlink), this to avoid interference between the signals the satellite
receives and retransmits to and from Earth, respectively
 3. Covered Area: Regions over which the satellite transmits or receives
signals. GEO satellite, might “see” one third of the earth surface; regions
actually covered depend on the design of antenna systems, RF.
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
OSR SHARING
Two satellites can operate simultaneously, if:
 1. Cover Different Regions: operate since the same position, using the
same frequency bands, but radiating different regions, which are not
geographically contiguous, e.g., North America and South America
 2. Use Different Frequencies: operate since the same position, radiating
the same regions, or geographically contiguous, but operating on different
frequencies, e.g., both of them covering the Americas, but in C and Ku
band respectively
 3. Placed at Different Orbit Slot: radiate the same regions, or
geographically contiguous ones, using the same frequency bands, but
separate at least 3° or 2° (C or Ku Band) ; e.g. both covering the Americas,
both in C and Ku band, but operating from 120° and 123° respectively.
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
1. GEO Occupancy Use density, GOU
Aimed to measure the average number of Transponders TRP- per Area unit for a given satellite, or targeted for a space
network filed before ITU. It is defined as:
GOU= [ NB/MB (TRPs/Million Square Km)] /B
Where:
- NB: Number of TRPs of a given Beam B
- MB: Deserved Area for a given Beam (for this exercise, only
landmasses or maritime populated areas are considered
- B: Number of Beams
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
2. GEO Reuse Factor, GRF
Allows to measure the reuse of the SOR done from a given
orbit slot, or also to compare the efficient use of SOR from
different satellites.
It is defined as the ratio between a single global beam
satellite and any other one
GRFx = GOUx / GOUref
Where:
- GOUx: GOU of a slot X
- GOUref: GOU for X slot if a single Global Beam were used
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
3. GEO Area Service, GAS
Allows to measure, for a given Area, the total GOU, radiated
over it, since any position. It is determined as:
GASR =  GOUR
Where
- R: Considered Region
- GOUR: any GOU attending such region R (total or partial)
When calculating GASR attention must be taken for every
GOUR, only considering beams including such a region. For
partial coverage, a weighting must be done, multiplying that
GEO by the covered zone over the total zone
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
4. Maximal GASR for a region R, GASMR
Allows to measure the maximal GAS for a Region R,
considering that since a given position a same area can not
have more TRPs than the whole Band (dedicated Beam).
Thus GASMR is calculated from its total GEO visible arc, with
an orbit separation according to the Band, and assuming a
Region Beam from each position.
GASMR =
 GOUR (for all GEO visible Arc, dedicated Beam,
whole Band)
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
5. GEO saturation of a given region R, GSR
For a given region R, it is the ratio between is current GASR
and its maximal GASMR.
GSR = GASR / GASMR
Where:
- GSR: actual GAS for a region R
- GSMR: Maximal GAS for a region R,
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
EXAMPLE
A Satellite A over Atlantic Ocean, with 36 TRPs in Ku Band, in a
Global Beam: Americas (58.6 Millions Km2), Europe (23 Millions
Km2) and Africa (30.2 Millions Km2); hence:
1. GOUA = [36/(58.6+23+30.2)]/1=36/11.8 = 0.322 TRP/Million
Km2
A satellite B uses 4 zonal beams: North America South America,
Europe, and Africa, each beam with whole Ku Band (36 TRPs):
1. GOUB =[36/20+36/17.9+36/23+36/30.2]/4=
1.65TRP/Million Km2
2. GRFB= 1.65 / 0.322 = 5.12
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
EXAMPLE
Taking as R South America, a visible arc of 120.0°, (Elevation
angle >20.0°) ), in Ku Band, with at least 2.0°separation; it can be
implemented 60 beams, each one from different orbit slot, spaced
2.0 °) . Then, for this region its GASRM is:
4. GASRM: 120/2 (# of slots) x 36 (# of TRP) / 17.9 (South
America Area) = 120.6 TRP/Million Km2
I the sum of current GASR for South America were, 60.3, then:
5. GSR= 60.3 /120.6 = 0.5 = 50%
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
EXAMPLE
Taking as R South America, a visible arc of 120.0°, (Elevation
angle >20.0°) ), in Ku Band, with at least 2.0°separation; it can be
implemented 60 beams, each one from different orbit slot, spaced
2.0 °) . Then, for this region its GASRM is:
4. GASRM: 120/2 (# of slots) x 36 (# of TRP) / 17.9 (South
America Area) = 120.6 TRP/Million Km2
I the sum of current GASR for South America were, 60.3, then:
5. GSR= 60.3 /120.6 = 0.5 = 50%
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
VARIABLES TRADE OFF
Symbol
SLOT ORIENTED
GEO Occupancy Use density, for a slot S, several or dedicated Beams GOUS
GEO Occupancy Use density, for a slot S, Single Global Beam
GOUS
GEO Reuse Factor, for a slot S
GRFS
REGION ORIENTED
GEO Area Service, for a Region R
GASR
Maximal GEO Area Service , for a Region R
GASMR
GEO Saturation, for a Region R
GSR
Up
=
Up
Up
=
Up
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
POSIBLE STUDIES
1. Historic behavior of GEO exploitation: evaluating how the GFR has
been increased by introduction of new techniques both in antenna design
and manufacturing and signal processing, not only for a given GEO Arc, but
also for the deserving different Regions.
2. Regulatory and Commercial GEO Status: it can be used both for the
spacecrafts placed onto GEO and satellite networks notified before ITU, to
analyze the GEO occupancy since the commercial and regulatory
perspectives.
3. Comparisons between commercial and regulatory approach: to
compare the quantity of SOR reserved vs. exploited, both from GEO Arcs
and deserved regions perspective.
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
APPLICATION TO BASIC PRINCIPLES (Res. 80)
1. Efficiency: the GFR allows measuring a given GEO Arc efficiency vs time,
looking last 40 years of GEO exploitation, and foreseeing their evolution,
based on future satellites and notified or networks or in coordination. It can
also applied for GASR, analyzing their increase vs time for a given Region
2. Economical: comparing the average cost per TRP vs time, then applied to
average GOUS cost or GASR cost, showing the cost reduction or increase. It
can be focused since satellite cost (industry view) or space capacity leasing
(users view), and compare it, to answer questions as: a more economic
GOUS leads to a cheaper GASR ?, in other words, how the economy
benefits of GOUS evolution is being transferred to GASR ?
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
APPLICATION TO BASIC PRINCIPLES (Res. 80)
3. Equitable Access: It can be deducted by comparing the GASR and GASMR
for different Regions; also it can be done by comparing by considering
specific administrations exploiting a given GOUS they have notified before
ITU.
4. Equitable Access for Developing Countries: As the equitable Access,
using as a Region a given Country, or Group of Countries. Also it might be
extended to particular geographical situations, as arctic or tropical regions.
5. . Rationality: it can be derived from comparisons between satellites in
GEO vs notified networks,
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Methodology for Measuring the
GEO Exploitation
Ministry for
Communications
Republic of Colombia
CONCLUSIONS AND FURTHER WORKS
1. With this mathematical approach, measurable analyzes of the
basic principles ruling the SOR exploitation can be conducted,
and also measurable conclusions can be attained.
2. Impact of current or proposed regulatory procedures can be
analyzed or simulated respectively.
3. These analyses can support modifications to RR procedures or
the inclusions of new considerations, in order to improve an
actual achievement of every basic principle.
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Ministry for
Communications
Republic of Colombia
THANK YOU!
Further Information:
Joaquin G. Restrepo
jgrestrepo@mincomunicaciones.gov.co
Ministry for Communications:
www.mincomunicaciones.gov.co
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