Radiocommunication Study Groups
Document 7C/TEMP/57-E
9 September 2009
English only
Working Party 7C
PRELIMINARY DRAFT NEW REPORT ON SHARING THE 31.5-31.8 GHz BAND
BY THE EARTH EXPLORATION-SATELLITE SERVICE
(PASSIVE) AND THE FIXED SERVICE
1
Introduction
Question ITU-R 232-1/7 calls for studies to determine what the criteria for sharing the bands
10.6-10.68 GHz, 31.5-31.8 GHz and 36-37 GHz between the Earth exploration-satellite service
(passive) and other services should be. The bands 10.6-10.68 GHz and 36-37 GHz were dealt with
under Agenda item 1.2 at WRC-07 and the studies for those bands have been completed. To date,
the 31.5-31.8 GHz band has not been studied.
In Region 2, the band 31.5-31.8 GHz is exclusively allocated to passive services and all emissions
are prohibited in the band by RR No. 5.340. However, in Regions 1 and 3, the 31.5-31.8 GHz
band is allocated on a secondary basis to the fixed and mobile (except aeronautical) services.
Furthermore, RR No. 5.546 allocates the band 31.5-31.8 GHz to the fixed and mobile (except
aeronautical) services on a primary basis in some 29 administrations in Region 1. This contribution,
using methodologies similar to the studies completed for the 10.6-10.68 GHz and 36-37 GHz bands
as documented in Reports ITU-R RS.2096 and ITU-R RS.2095 respectively, is intended to begin
the effort to complete the work outlined by Question ITU-R 232-1/7 for the band 31.5-31.8 GHz.
2
Earth exploration-satellite service (passive)
2.1
Applications
The 31.3-31.5 GHz and 31.5-31.8 GHz bands are used to measure water vapour, cloud liquid water,
Earth surface temperature, indicate sea ice, and they are also used in conjunction with 50 to 60 GHz
bands for atmosphere temperature sounding. This data is used for weather forecasting as well as
atmospheric research.
These sensors are typically flown on polar orbiting satellites. These missions offer frequent
observations of the Earth, with each satellite providing global daily coverage.
The AMSU instrument operates in the 31.3-31.5 GHz band and is currently used on NASA’s
AQUA spacecraft, NOAA’s NOAA-15 thru 19 satellites, EUMETSAT’s METOP-A satellite, and
future METOP-B mission. The band will continue to be used for measurements with next
generation instruments on the NPP and NPOESS missions’ ATMS instrument.
Attention: The information contained in this document is temporary in nature and does not necessarily represent material that has been agreed by the
group concerned. Since the material may be subject to revision during the meeting, caution should be exercised in using the document for the
development of any further contribution on the subject.
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2.2
Passive sensor parameters
The sensor used in these simulations is based on the AQUA spacecraft’s AMSU instrument.
The parameters selected are from preliminary draft new Recommendation ITU-R
RS.[PASSIVE_CHARS] [found in Annex 3 to Document 7C/32]. The AMSU instrument has an
instantaneous circular 3.3° field of view, and the instrument scans a total field of view of ±48.3° to
the nadir, measuring a swath of 2 343 km in an 8 second cycle. While the AMSU instrument’s
centre frequency is 31.4 GHz, the operation characteristics are similar to those that could be applied
in the 31.5-31.8 GHz band. The operational geometry of the AMSU passive sensor is illustrated in
Fig. 1. Table 1 provides the EESS (passive) sensor characteristics required for the simulation
studies, while Fig. 2 shows the AMSU antenna gain pattern as a function of off-axis angle.
TABLE 1
EESS (passive) sensor characteristics in the 31.3-31.8 GHz band
Sensor 1
[AMSU-A]
Sensor 2
[ATMS]
Sensor 3
[MTVZA-OK]
Nadir scan
Nadir scan
Conical scan
833 km
824 km
835 km
Inclination
98.6°
98.7°
98.85°
Eccentricity
0.001
Repeat period
9 days
9 days
30 earth fields per
8 sec. scan period
96 earth fields per
scan period
34.4 dBi
30.4 dBi
.30 m
0.203 m
0.6 m
V
QV
H, V
3.3°
5.2°
±48.33° crosstrack
±52.725° crosstrack
55.4
8 sec scan period
8/3 sec scan period
cross track
2.88 sec scan period
Sensor type
Orbit parameters
Altitude
0
Sensor antenna parameters
Number of beams
Maximum beam gain
Reflector diameter
Polarization
–3 dB beamwidth
Off-nadir pointing angle
Beam dynamics
Incidence angle at Earth
–3 dB beam dimensions
Instantaneous field of view
Main beam efficiency
Swath width
1
65°
49.1 km
Nadir FOV: 48.5 km
Outer FOV: 149.1 ×
79.4 km
Nadir FOV: 74.8 km
Outer FOV:
323.1.1 ×
141.8 km
95%
95%
2 343 km
2 500 km
34.4 dBi
30.4 dBi
30 km × 69 km
2 000 km
Sensor antenna pattern
Cold calibration ant. gain
Cold calibration angle
(degrees re. satellite track)
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Cold calibration angle
(degrees re. nadir direction)
Sensor 1
[AMSU-A]
Sensor 2
[ATMS]
83.33
82.175
158 msec
18 msec
180 MHz centred at
31.4 GHz
180 MHz centred at
31.4 GHz
Sensor 3
[MTVZA-OK]
Sensor receiver parameters
Sensor integration time
Channel bandwidth
0.5 GHz
Horizontal resolution
38 km
Vertical resolution
38 km
FIGURE 1
AMSU operational geometry
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FIGURE 2
AMSU antenna gain pattern
2.3
Interference criteria
Recommendation ITU-R RS.1029-2 provides permissible interference levels and reference
bandwidths for use in any spaceborne passive sensor interference assessment or sharing studies. The
permissible interference levels for the 31.5-31.8 GHz band are –160 dBW in a reference bandwidth
of 200 MHz for passive sensors in operation prior to 2003, and –166 dBW in a reference bandwidth
of 200 MHz for newer passive sensors that are more sensitive than the previous operational passive
sensors. Recommendation ITU-R RS.1029-2 also specifies that these interference levels should not
be exceeded for more than 0.01% of sensor viewing area, described as a measurement area of a
square on the Earth of 2 000 000 km2 unless otherwise justified in the 31.5-31.8 GHz band. When
these permissible interference levels are applied to a sensor with a 300 MHz bandwidth, the
interference level for passive sensors in operation prior to 2003 is –158.24 dBW, and –164.24 dBW
for newer passive sensors.
3
Active service parameters
3.1
Fixed service
In this study only a point-to-point type fixed service (FS) system was modelled. The P-P FS station
parameters used in the analysis are given in Table 2. This data is based on Recommendation ITU-R
F.758-4, though the particular band being studied is not in the Recommendation, so the data used is
taken from the adjacent 31.8-33.4 GHz band.
TABLE 2
P-P terrestrial FS station parameters
Parameter
Maximum transmitter power (dBW)
Antenna gain, dBi
Antenna diameter, m
Antenna type
Antenna pattern
e.i.r.p. (maximum)
Channel spacing
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FS
–3 to –15 dBW
43 to 46 dBi
.6 m, .9 m
Parabolic
Rec. ITU-R F.1245-1
28-43 dBW
3.5-40 MHz
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TABLE 3
P-P terrestrial FS station parameters for 31.5-31.8 GHz band
Parameter
Maximum transmitter power
Antenna gain
Antenna diameter
Antenna type
Antenna pattern
e.i.r.p. (maximum)
Channel spacing
Path length
4
FS
–20 to –10 dBW
Typical: –18 dBW
27 to 42 dBi
Typical: 36 dBi
0.15 to 0.6 m
Typical: 0.3 m
Parabolic and Planar
Rec. ITU-R F.1245-1
7 to 32 dBW
Typical: 15 dBW
28 MHz
< 100 m to 10 km
Typical/mean < 2 km
Simulation studies
Typically, passive sensors are flown on high inclination low Earth orbit (LEO) satellites, and these
sensors have shown to be sensitive to the cumulative effects of interference from other services. An
effective method to study these effects is through a dynamic simulation of a sensor’s operation and
the interaction with realistic representations of other systems and comparing the results to the
interference criteria as recommended in Recommendation ITU-R RS.1029.
Since high inclination satellites do not cover the same region on every orbit, it is necessary to
simulate a sufficient amount of time to ensure the appropriate coverage of the region. Also, there
are several different types of sensors and it is important to consider when the sensor footprint is
within a specified area. In these cases, a satellite orbits the earth a sufficient number of days such
that an area in question is adequately covered.
4.1
Simulation Study 1
4.1.1
Simulation Study 1 FS station distribution
Since the interference criteria for passive sensors in this band correspond to an area of
2 000 000 km2, a test area can be selected anywhere on the Earth. But some arbitrary areas could
consist entirely of ocean and therefore not have any FS stations, or an area could contain many
densely populated regions where the FS has an extensive presence, neither of which would be an
accurate representation of what might be considered “normal”.
This first simulation test area is a rectangular 2 000 000 km2 area defined by 56.5° N latitude, 13° E
longitude, 45° N latitude 35.23° E longitude. This area encompasses four nations where the
31.5-31.8 GHz band is allocated on a primary basis to the fixed service (FS) as identified in
RR 5.546. The four nations selected in this region cover 647 155 km2, or 32.3% of the test area.
The FS station deployment strategy employed for this study is a simple 50 km grid for each country.
The test area and FS deployment is shown in Fig. 3. While deploying FS stations evenly may not be
an accurate representation of this particular region, it does provide a general sense of the
interference impact of FS stations operating in this band.
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4.1.2
Simulation Study 1 configuration
All of the stations employ a single antenna with a 41 dBi gain, and a maximum EIRP of 31 dBW,
antennas are randomly pointed in azimuth and have a 1.1° elevation angle.
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1.
The simulation time increment used is 1 second, and the simulation is for a duration of 7 days.
Output data is taken from the simulation and is further processed, by calculating spacecraft heading
and sensor angle, to eliminate any data point where the sensor footprint does not fall within the
simulation test area.
Additional Simulation Study 1 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are co-frequency.
–
FS stations are pointed randomly.
FIGURE 3
Simulation study area
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FIGURE 4
FS interference into AMSU
AMSU Interference Simulation
100.0000%
Fraction of Area Exceeding Limit
10.0000%
1.0000%
0.1000%
0.0100%
0.0010%
-220
-210
-200
-190
-180
-170
-160
-150
Interference Power Level (dBW)
4.1.3
Simulation Study 1 results
The simulation results in Fig. 4 show that the interference threshold for a pre-2003 passive sensor,
–158.24 dBW is met, while a modern passive sensor sensor’s interference threshold is
–164.24 dBW is exceeded 0.08% of the time when the sensor footprint is within the measurement
area.
4.2
Simulation Study 2
4.2.1
Simulation Study 2 FS station distribution
Another approach is to deploy FS stations based on population. Using the same test area as
Simulation Study 1, a rectangular 2 000 000 km2 area defined by 56.5° N latitude, 13° E longitude,
45° N latitude 35.23° E longitude, cities with a population of at least 100 000 people in or near the
test area were considered.
A selected city was assigned a random number of links from 1-20, where a link consists of two
stations pointing at each other in order to emulate the two-way functionality of typical FS systems.
These cities and locations are not limited to the nations used in Simulation Study 1. The first station
in a link was randomly placed within 20 km of the city centre, and the second station in a link was
randomly placed within 20 km of the first station.
This method led to the selection of 188 cities and the creation of 3916 FS stations in and around the
test area; these stations are shown in Fig. 5.
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4.2.2
Simulation Study 2 configuration
The FS stations created are similar to those used in Simulation Study 1 with all of the stations
employing a single transmit antenna with a 41 dBi gain and a maximum EIRP of 31 dBW.
Additional simulation Study 2 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are co-frequency.
FIGURE 5
Simulation Study 2 test area
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1.
The simulation time increment used is 1 second, and the simulation is for a duration of 6 days and
6 hours. Output data is taken from the simulation and is further processed, by calculating spacecraft
heading and sensor angle, to eliminate any data point where the sensor footprint does not fall within
the simulation test area.
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FIGURE 6
Interference from random city based FS deployment to AMSU
Study 2 Interference
100.00000%
Percentage Area
10.00000%
1.00000%
0.10000%
0.01000%
-220
-210
-200
-190
-180
-170
-160
-150
Interference Power (dbW)
4.2.3
Simulation Study 2 results
The results of Simulation Study 2, shown in Fig. 6, show that the pre-2003 sensor interference
criteria of –158.24 dBW is exceeded nearly 0.2% of the time studied, and the current sensor
interference criteria of –164.24 dBW is exceeded 0.4% of the time studied. Both exceed the
interference criteria given in Recommendation ITU-R RS.1029.
4.3
Simulation Study 3
4.3.1
Simulation Study 3 FS station distribution
Simulation Study 3 uses the same FS Station Distribution as Simulation Study 2, and is described in
section 4.2.1.
4.3.2
Simulation Study 3 configuration
The FS stations use the parameters in Table 2. Channel spacing and bandwidth are randomly
assigned for each fixed service station, histograms of the channel spacing and bandwidths are in
Fig. 7. This simulation is run five times, FS stations transmitting at –10 dBW, –20 dBW, –30 dBW,
–35 dBW and –40 dBW.
Simulation Study 3 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are transmitting at the same power.
–
All FS stations are assigned frequencies within the 31.4-31.8 GHz band.
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FIGURE 7
FS station frequencies and bandwidths used in the simulation
Histogram of randomly assigned FS frequencies
Histogram of randomly assigned FS bandwidths
160
1400
140
1200
120
1000
800
Count
Count
100
80
600
60
31.81
31.79
31.77
31.75
31.73
31.71
31.69
31.67
31.65
31.63
31.61
31.59
0
31.57
0
31.55
200
31.53
20
31.51
400
31.49
40
0
5
10
Range
15
20
25
30
Range
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1.
The simulation time increment used is 1 second, and the simulation is for a duration of 7 days.
Output data is taken from the simulation and is further processed, by calculating spacecraft heading
and sensor angle, to eliminate any data point where the sensor footprint does not fall within the
simulation test area.
FIGURE 8
Interference from random city based FS deployment to AMSU
100.0000%
10.0000%
1.0000%
0.1000%
Power =-10 dBW
Power = -20dBW
Power = -30 dBW
Power = -35 dBW
Power = -40 dBW
0.0100%
-220
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-200
-190
-180
-170
-160
-150
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4.3.3
Simulation 3 results
The results of the simulation are shown in Fig. 8. The simulation with FS stations transmitting at a
power of –10 dBW exceeds the pre-2003 sensor interference criteria of –158.24 dBW over 15% of
the time studied, and the current sensor interference criteria of –164.24 dBW approximately 50% of
the time studied. These numbers improve as the FS transmit power was reduced, with FS stations
transmitting at a power of –35 dBW meeting the pre-2003 criteria of –158.24 dBW, and FS stations
transmitting at a power or –40 dBW meeting the current sensor interference criteria of
–16 424 dBW.
4.4
Simulation Study 4
4.4.1
Simulation Study 4 FS station distribution
Another alternate population based FS deployment approach is used in Simulation Study 4. Using
the same test area as Simulation Study 1, a rectangular 2 000 000 km2 area defined by 56.5° N
latitude, 13° E longitude, 45° N latitude 35.23° E longitude, cities with a population of at least
100 000 people in or near the test area were considered.
A selected city was assigned a random number of links from 1-20, where a link consists of two
stations pointing at each other in order to emulate the two-way functionality of typical FS systems.
These cities and number of links per city are identical to those used in Simulation Study 3. The first
station in a link was randomly placed within 10 km of the city centre, and the second station in a
link was randomly placed within 10 km of the first station, in both instances the 10 km is a
maximum limitation, and a majority of stations were selected within 2 km of the city centre or first
station in a link pair. The range distribution of these stations is shown in the histogram of Fig. 9.
This method led to the selection of 188 cities and the creation of 3 916 FS stations in and around the
test area; these stations are shown in Fig. 10, based on the cities selected and the FS link
distribution, there is an average population of 65 794.48 per FS link.
FIGURE 9
Simulation Study 4 FS link ranges
Histogram of FS Link Ranges
120
100
80
60
40
20
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
5.5
6
6.5
7
7.5
8
8.5
9
9.5
10
Range (km)
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FIGURE 10
Simulation Study 4 FS station locations
4.4.2
Simulation Study 4 configuration
The FS stations use the parameters in Table 2. Channel spacing and bandwidth are randomly
assigned for each fixed service station, histograms of the channel spacing and bandwidths are in
Fig. 11.
Simulation Study 4 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are assigned frequencies within the 31.5-31.8 GHz band.
–
Terrain and buildings are not taken into account.
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FIGURE 11
FS station frequencies and bandwidths used in Simulation Study 4
Simulation Study 4 FS Frequencies
160
140
Number of FS Stations
120
100
80
60
40
20
31
.5
31 0
.5
31 1
.5
31 2
.5
31 3
.5
31 4
.5
31 5
.5
31 6
.5
31 7
.5
31 8
.5
31 9
.6
31 0
.6
31 1
.6
31 2
.6
31 3
.6
31 4
.6
31 5
.6
31 6
.6
31 7
.6
31 8
.6
31 9
.7
31 0
.7
31 1
.7
31 2
.7
31 3
.7
31 4
.7
31 5
.7
31 6
.7
31 7
.7
31 8
.7
31 9
.8
0
0
Frequencies (GHz)
Simulation Study 4 Simulation Bandwidths
1350
1300
Number of FS Stations
1250
1200
1150
1100
1050
1000
3.5
14
28
Bandwidth (MHz)
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1.
The simulation time increment used is 1 second, and the simulation is for a duration of 7 days.
Output data is taken from the simulation and is further processed, by calculating spacecraft heading
and sensor angle, to eliminate any data point where the sensor footprint does not fall within the
simulation test area.
The simulation is repeated with the same FS stations configurations but with the links transmitting
at different power levels, 15 dBW, 10 dBW, 5 dBW, 0 dBW, –5 dBW, –25 dBW, –30 dBW and
–35 dBW.
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4.4.3
Simulation Study 4 results
The results of the simulation are shown in Fig. 12. The simulations FS stations transmitting at
–25 dBW meets the pre-2003 sensor interference criteria of –158.24 dBW over 0.01% of the time
studied, but at this power level, the current sensor interference criteria of –164.24 dBW is
experienced approximately 0.6% of the time studied. The trend of these results is that the sharing
situation improves as the FS transmit power is reduced, with FS stations transmitting at a power of
–25 dBW meeting the pre-2003 criteria of –160 dBW, while the simulation with FS stations
transmitting at a power of –30 dBW meet both interference criteria.
FIGURE 12
Interference from random city based FS deployment to AMSU
(FS Range limited to 10km)
100.00000%
%
10.00000%
1.00000%
0.10000%
0.01000%
-220
Power = 15 dBW
Power =10 dBW
Power = 5 dBW
Power = 0 dBW
Power = -5 dBW
Power = -25 dBW
Power = -30 dBW
Power = -35 dBW
-210
-200
-190
-180
-170
-160
-150
-140
-130
-120
-110
-100
Interference
4.5
Simulation Study 5
4.5.1
Simulation Study 5 FS station distribution
As the FS deployment density is an important factor in determining interference into an EESS
(passive) sensor, Simulation Study 5 introduces another population based FS deployment scenario.
Using the same test area as Simulation Study 1, a rectangular 2 000 000 km2 area defined by
56.5° N latitude, 13° E longitude, 45° N latitude 35.23° E longitude, cities with a population of at
least 100 000 people in or near the test area were considered.
A selected city was assigned a random number of links from 1-10, where a link consists of two
stations pointing at each other in order to emulate the two-way functionality of typical FS systems.
These cities and number of links per city are identical to those used in Simulation Study 3. The first
station in a link was randomly placed within 10 km of the city centre, and the second station in a
link was randomly placed within 10 km of the first station, in both instances the 10 km is a
maximum limitation, and a majority of stations were selected within 2 km of the city centre or first
station in a link pair. The range distribution of these stations is shown in the histogram of Fig. 13.
This method led to the selection of 188 cities and the creation of 1 910 FS stations in and around the
test area; these stations are shown in Fig. 14, based on the cities selected and the FS link
distribution, there is an average population of 134 896 per FS link.
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FIGURE 13
Histogram of FS Link Ranges
60
50
40
30
20
10
10
9
9.
5
8
8.
5
7
7.
5
6
6.
5
5
5.
5
4
4.
5
3
3.
5
2
2.
5
1
1.
5
0
0.
5
0
Range (km)
FIGURE 14
4.5.2
Simulation Study 5 configuration
The FS stations use the parameters in Table 2. Channel spacing and bandwidth are randomly
assigned for each fixed service station, histograms of the channel spacing and bandwidths are in
Fig. 15.
Simulation Study 4 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are assigned frequencies within the 31.5-31.8 GHz band.
–
Terrain and buildings are not taken into account.
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FIGURE 15
Simulation Study 5 Frequencies
90
80
70
60
50
40
30
20
10
31
.5
31
.5
1
31
.5
2
31
.5
3
31
.5
4
31
.5
5
31
.5
6
31
.5
7
31
.5
8
31
.5
9
31
.6
31
.6
1
31
.6
2
31
.6
3
31
.6
4
31
.6
5
31
.6
6
31
.6
7
31
.6
8
31
.6
9
31
.7
31
.7
1
31
.7
2
31
.7
3
31
.7
4
31
.7
5
31
.7
6
31
.7
7
31
.7
8
31
.7
9
31
.8
0
Frequency (GHz)
Histogram of Bandwidths used in Simulation 5
700
680
660
640
620
600
580
560
540
520
3.5
14
28
Bandwith (MHz)
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1.
The simulation time increment used is 1 second, and the simulation is for a duration of 7 days.
Output data is taken from the simulation and is further processed, by calculating spacecraft heading
and sensor angle, to eliminate any data point where the sensor footprint does not fall within the
simulation test area. The simulation is repeated for different FS power levels, 15 dBW, 10 dBW,
5 dBW, 0 dBW, –5 dBW, –25 dBW, –30 dBW, and –35 dBW.
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4.5.3
Simulation Study 5 results
FIGURE 16
Interference from random city based FS deployment to AMSU
(FS limit = 10 stations per city)
100.00000%
%
10.00000%
1.00000%
0.10000%
0.01000%
-220
Power = 15 dBW
Power = 10 dBW
Power = 5 dBW
Power = 0 dBW
Power = -5 dBW
Power = -25 dBW
Power = -30 dBW
Power = -35 dBW
-210
-200
-190
-180
-170
-160
-150
-140
-130
-120
-110
-100
Interference (dBW)
The results of the simulation are shown in Fig. 16. The simulations with FS stations transmitting at
a power of –30 dBW meets the pre-2003 sensor interference criteria of –158.24 dBW over 0.01% of
the time studied, but the current sensor interference criteria of –164.24 dBW approximately 0.7% of
the time studied. The trend of these results is that the sharing situation improves as the FS transmit
power is reduced, with FS stations transmitting at a power of –30 dBW meeting the pre-2003
criteria of –158.24 dBW, while exceeding the current sensor interference criteria by 0.06%, and
with FS stations transmitting at a power of –35 dBW meeting both interference criteria.
4.6
Simulation Study 6
4.6.1
Simulation Study 6 FS station distribution
As the FS deployment density is an important factor in determining interference into an EESS
(passive) sensor, Simulation Study 6 introduces another population based FS deployment scenario.
Using the same test area as Simulation Study 1, a rectangular 2 000 000 km2 area defined by
56.5° N latitude, 13° E longitude, 45° N latitude 35.23° E longitude, the FS stations are all
configured as in Table 3, each simulation has decreasing numbers of stations deployed in order to
determine the sensitivity to the FS deployment density.
FS station deployment was based upon city population size, but the number of FS links and
maximum number of links per city were varied for each simulation in order to vary the total number
of FS stations in an individual simulation. Simulations with 868, 344, 112, 48, and 8 FS stations
were run.
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4.6.2
Simulation Study 6 configuration
Simulation Study 6 assumptions:
–
All FS stations are always transmitting.
–
All FS stations are assigned frequencies within the 31.5-31.8 GHz band.
–
Terrain and buildings are not taken into account.
The study is a dynamic simulation with a non-GSO passive sensing satellite as described in Table 1,
and FS stations described in Table 3. The simulation time increment used is 1 second, and the
simulation is for a duration of 7 days. Output data is taken from the simulation and is further
processed, by calculating spacecraft heading and sensor angle, to eliminate any data point where the
sensor footprint does not fall within the simulation test area. Each FS station deployment simulation
is run independently.
4.6.3
Simulation Study 6 results
The results of Simulation Study 6 are shown in Fig. 17. The interference received by the AMSU
sensor in the 868 FS station simulation meets the pre-2003 criteria, but exceeds the post-2003
sensor criteria by approximately 0.4%. Of the FS deployment densities selected for this study, the
112, 48 and 8 station scenarios meet both the pre, and post-2003 criteria.
FIGURE 17
Interference from random city based FS deployment to AMSU
(varying FS deployment densities)
100.00000%
868 Stations
344 stations
112 stations
10.00000%
48 Stations
8 stations
1.00000%
0.10000%
0.01000%
-200
-190
-180
-170
-160
-150
Interference (dBW)
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5
Summary
The preliminary results from Study 1 and Study 2 show that the cumulative interference from the
fixed service exceeds the interference criteria as given in Recommendation ITU-R RS.1029-2.
While Study 2 exhibits sensitivity to the increased number of fixed service stations over Study 1,
there is likely an overestimation of interference since both studies were conducted with cofrequency transmitters. Results from Study 3 demonstrate that the combined effects of the FS
stations offer more interference to the passive sensor when the FS station transmissions are
concentrated into smaller bandwidths than in the Studies 1 and 2. Decreasing the power of the
stations reduces this effect, and a sufficient reduction in transmitter power would result in the FS
stations meeting the interference criteria.
Simulation Study 4 and Simulation Study 5 show a reduction of interference from Simulation
Study 3 based on shorter range FS deployments, and in the case of Simulation Study 5, fewer FS
stations. And with sufficiently low amounts of power emitted from the FS stations, the interference
criteria can be met in both studies.
Simulation Study 6 further investigates the sensitivity of FS station deployment using FS station
characteristics in Table 3. This study uses fewer FS stations within the test area selected, but shows
that the interference criteria can be met with higher power FS stations than in Simulation Studies 3,
4 and 5, but with much fewer stations.
Since the FS transmitters are always transmitting, these studies provide worst-case scenarios.
Further studies involving more detailed fixed service performance characteristics in this band
should be conducted to better define the interference statistics.
6
Future work
In order to complete the work started in Studies 1 through 6, further sensitivity of the results to the
density of FS stations defined in Table 3 should also be examined, as well as applying the technical
information contained in Table 3 to improve Simulation Studies 1 through 5 where applicable. Also,
similar studies should be carried out with EESS (passive) and the terrestrial mobile service.
Additionally, any of these studies could be further refined with improved system data in place of the
data already used.
7
Supporting documents
[1]
Recommendation ITU-R RS.1029-2: Interference criteria for satellite passive remote sensing.
[2]
Report ITU-R RS.2095: Sharing of the 36-37 GHz band by the fixed and mobile services and the
Earth exploration-satellite service (passive).
[3]
Report ITU-R RS.2096: Sharing of the 10.6-10.68 GHz band by the fixed and mobile services and
the Earth exploration-satellite service (passive).
[4]
Preliminary draft new Recommendation ITU-R RS.[PASSIVE_CHARS]: Typical technical and
operational characteristics of Earth exploration-satellite service (passive) systems operating below
275 GHz.
[5]
Recommendation ITU-R F.758-4: Considerations in the development of criteria for sharing between
the fixed service and other services.
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