CEPT
ECC/CPG15
ECC
CPG PTB(2013)056
Electronic Communications Committee
3rd meeting CPG-15 PTB
Copenhagen, 21-23 August 2013
Date issued:
09 August 2013
Source:
Luxembourg
A.I. 1.6.1 – Compatibility studies related to the band 13.25-13.75 GHz
between EESS (active) and FSS (s-E)
N
Password protection required:
Subject:
Summary:
This study shows the results of compatibility between EESS (active) networks (current and future) and a new
FSS (s-E) allocation in the band 13.25-13.75 GHz.
Considering the deployment model developed by the WP4A to be used for statistical and dynamic simulations,
different Earth stations latitudes, different antenna sizes and different elevation angles, the simulation depicts
situations where the interference generated by EESS (active) systems exceed the FSS (s-E) protection criteria
for a very limited period of time. This therefore confirms that FSS (space-to-Earth) and EESS (active)
demonstrate compatibility.
Considering the potential interference of the ACES system operating under the SRS allocation, it was not
possible to address this sharing situation due to lack of information (e.g. the number of Uplink ACES stations,
the location, the antenna diameter of such uplink ACES stations, etc.).
Proposal:
In view of these preliminary study results, CPG PTB is invited to consider the band 13.25-13.75 GHz as a
potential band for FSS (space-to-Earth) allocations in ITU Region 1 under WRC-15 Agenda item 1.6.1 and to
continue the sharing studies with particular attention given to the possible impact of the aggregate interference
coming from all EESS (active) systems simultaneously.
1
1. Introduction
Under Resolution 151 (WRC-12), the band 13.25-13.75 GHz falls within the scope of a new space-to-Earth FSS new
allocation. The band is currently allocated to different services and in particular EESS (active) systems.
WP4A at the last meeting in May 2013 meeting developed a more detailed FSS deployment model to be used for
statistical and dynamic analyses.
This contribution analyses the potential interference of some EESS (active) systems towards an FSS Earth station. To
assess this potential interference, the same EESS (active) systems as used in documents CPG PTB(2013)019 and the
Luxembourgish contribution to this meeting for an uplink compatibility, were used (i.e. Altimeter JASON-3 and
SENTINEL-3, scatterometer QuickSCAT and precipitation radar TRMM).
2. FSS deployment model
Document 4A/242 Annex 5 gives characteristics of a downlink FSS deployment model provided by a satellite
operator based on the current deployment observed on their own Ku FSS fleet and a typical equivalent noise
temperature of all FSS earth stations in Ku band. These parameters are reproduced in Table 1 below.
Receive earth station
diameter (DES)
TABLE 1
FSS deployment model
Average
Percentage of Average power
density
bandwidth
total
(dBW/Hz)
(MHz)
bandwidth
Noise
Temperature
(° K)
DES <= 75 cm
25.9
69.0%
-20.1
140
75 cm < DES <= 1.2 m
1.8
5.0%
-31.0
140
1.2 m < DES <= 1.8 m
0.5
0.7%
-29.4
140
1.8 m < DES <= 2.4 m
1.0
3.2%
-30.2
140
2.4 m < DES <= 4.5 m
0.7
4.7%
-31.3
140
4.5 m < DES <= 9 m
0.5
11.2%
-31.6
140
DES > 9 m
0.6
6.2%
-32.5
140
The maximum allowable aggregate interference from other systems having co-primary status was used as a
criterion (aggregate interference/noise ratio, I/N = -12.2 dB (6%), taken from the Recommendation ITU-R
S.1432).
As the potential of interference of a NGSO system mainly depends on its respective position with regard the FSS
earth station – satellite line of sight, simulations were performed considering Earth stations at different latitudes
and with different elevation angles between the FSS earth station and the GSO FSS satellite.
Simulations were also performed for different receive FSS earth station diameters. Due to the time consuming
nature of the simulation, simulations were only performed with 3 of the typical antennas operated today in Ku
FSS (i.e. 60 cm, 1.2m and 7m antenna diameters).
2
3. EESS(active) characteristics
The EESS (active) characteristics are exactly the same as used in the document CPG PTB(2013)019 and they are
summarized in Table 2 for three different types of sensors.
TABLE 2
Characteristics of current flying spaceborne active sensors in the 13.25-13.75 GHz band
Parameters
Active sensor type and mission
Altimeter
JASON-1/2/3
SENTINEL-3
Scatterometer
QuickSCAT Seawinds
Precipitation radar
TRMM/
Orbit altitude, km
1 336 (JASON)
815 (SENTINEL-3)
803
350
Orbit inclination, deg
66 (JASON)
98 (SENTINEL-3)
98.2
35
Antenna type
1.2 m diameter parabolic
dish
1 m diameter parabolic
dish
Planar array
Antenna polarization
Linear
Horizontal (inner),
Vertical (outer)
Horizontal
Antenna peak gain, dBi
43.9
41.0
47.7
Antenna elevation
beamwidth, deg
1.28
1.6 (inner),
1.4 (outer)
0.71
Antenna azimuth
beamwidth, deg
1.28
1.8 (inner),
1.7 (outer)
0.71
Antenna beam look
angle, deg
0
40 (inner),
46 (outer)
–17 to +17
Antenna scan range, deg
0
0 to 360
–17 to +17 (cross track)
Antenna scan period, sec
0
3.33 (18 rpm)
0.7
Antenna pointing
Fixed at nadir
Circular scanning in
azimuth
Scanning across nadir
track
Centre RF frequency,
GHz
13.575 GHz and 13.285
GHz (JASON)
13.575 GHz (SENTINEL3)
13.402
13.597-13.796 GHz
13.603-13.802 GHz
Receiver bandwidth,
MHz
320 to 350
0.40
1
Comments
Nadir looking
Rotating dish antenna
with two spot beams
sweeping a circular
pattern. QuickSCAT has
4 look angles and the
resolution in conical
scan mode is 50 km.
Two channel frequency
agility; cross track
antenna scanning
3
4. Simulation for altimeters SENTINEL-3
For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have
been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with
different elevation angle between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°, 40°,
60° and 80°).
The SENTINEL-3 orbits are simulated during 27 days with a time step of 1 second.
The antenna patterns used for SENTINEL-3 are the same as used in the documents CPG PTB(2013)019 and
4A/168.
Figures 1 to 4 show the cumulative distribution function of I/N criteria during the simulation period for different
latitudes, different elevations and different antenna diameters. The vertical solid line on each figure represents
the I/N = -12.2 dB criteria.
FIGURE 1
Cdf of interference received on a 60 cm FSS Earth station located at 20° Latitude by SENTINEL-3
4
FIGURE 2
Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by SENTINEL-3
FIGURE 3
Cdf of interference received on a 1.2 m FSS Earth station located at 40° Latitude by SENTINEL-3
5
FIGURE 4
Cdf of interference received on a 7 m FSS Earth station located at 40° Latitude by SENTINEL-3
Table 3 shows an overview for all simulations of the percentage of time (in %) for which the interference
generated by SENTINEL-3 towards the FSS Earth station exceed the I/N criteria of 6%.
TABLE 3
Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%
“Na” means no possibility to have such elevation angle at such latitude
“< 0.001” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6% by
less than 0.001%
5. Simulations for altimeters JASON
For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have
been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with
different elevation angles between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°,
40°, 60° and 80°).
The JASON-3 orbits are simulated during 10 days with a time step of 1 second.
The antenna patterns used for JASON-3 are the same as used in the documents CPG PTB(2013)019 and 4A/168.
Figure 5 shows the cumulative distribution function of I/N criteria during the simulation period for a 60 cm FSS
earth station located at 40° latitude. The vertical solid line on each figure represents the I/N = -12.2 dB criteria.
6
FIGURE 5
Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by JASON-3
Table 4 shows an overview for all simulations of the percentage of time (in %) for which the interference
generated by JASON-3 towards the FSS earth station exceed the I/N criteria of 6%.
TABLE 4
Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%
“Na” means no possibility to have such elevation angle at such latitude
“< 0.001” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6%
during less than 0.001%
“0” means due to the orbital parameters of JASON-3, an FSS earth station at these latitudes never see this NGSO
6. Simulations for the scatterometer QuickSCAT
For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have
been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with
different elevation angles between the FSS earth station and the GSO satellite (i.e. elevation of 10°, 20°, 30°,
40°, 60° and 80°).
The QuickSCAT orbits are simulated during 4 days with a time step of 3.33 second. (3.33 second is antenna scan
period)
The antenna patterns used for QuickSCAT are the same as used in the documents CPG PTB(2013)019 and
4A/168. This antenna is a rotating dish antenna sweeping a circular pattern. As such use is not implemented in
the Visualyse software (used to perform these simulations), the simulations have been performed using a beam
7
pointing only in one direction. Due to the long period of simulation, it is assume that all possible configurations
are considered. As shown with Figures 6 and 7, the cumulative distribution function of I/N criteria during the
simulation period for a 60 cm FSS earth station located at 40° latitude for two different angles looks similar. The
angle is made with the velocity vector of the NGSO in a clockwise direction.
The vertical solid line on each figure represents the I/N = -12.2 dB criteria.
FIGURE 6
Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by QuickSCAT
FIGURE 7
Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by QuickSCAT
8
Table 5 shows an overview for all simulations of the percentage of time (in %) for which the interference
generated by QuickSCAT towards the FSS earth station exceed the I/N criteria of 6%.
TABLE 5
Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%
“Na” means no possibility to have such elevation angle at such latitude
“0.017” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6%
during 0.017%
7. Simulations for the precipitation radar
For this simulation, FSS earth stations at different latitudes (i.e. 0°, 10°, 20°, 30°, 40°, 50°, 60° and 70°) have
been deployed with an antenna pointed towards a GSO satellite. Several simulations have been performed with
different elevation angles between the FSS earth stations and the GSO satellite (i.e. elevation of 10°, 20°, 30°,
40°, 60° and 80°).
The TRMM orbits are simulated during 4 days with a time step of 1 second.
The antenna patterns used for TRMM are the same as used in the documents CPG PTB(2013)019 and 4A/168.
Figure 8 shows the cumulative distribution function of I/N criteria during the simulation period for a 60 cm FSS
earth station located at 40° latitude. The vertical solid line on each figure represents the I/N = -12.2 dB criteria.
FIGURE 8
Cdf of interference received on a 60 cm FSS Earth station located at 40° Latitude by JASON-3
9
Table 6 shows an overview for all simulations of the percentage of time (in %) for which the interference
generated by TRMM towards the FSS Earth station exceed the I/N criteria of 6%.
TABLE 6
Percentage of time (in %) for which the EESS (active) interference exceed the I/N criteria of 6%
“Na” means no possibility to have such elevation angle at such latitude
“< 0.001” means the interference generated by SENTINEL-3 towards the FSS earth station exceeds the I/N criteria of 6%
during less than 0.001%
8. Conclusion
Considering the FSS deployment model developed by WP4A to be used for statistical and dynamic simulations,
different FSS earth stations latitudes, different antenna sizes and different elevation angles, the simulations and
results presented above depict situations where the interference generated by EESS (active) systems exceed the
FSS (s-E) protection criteria for a very limited period of time. This therefore confirms that FSS (space-to-Earth)
and EESS (active) demonstrate compatibility.
It is therefore proposed that the band 13.25-13.75 GHz be considered as a potential band for a primary FSS
(space-to-Earth) allocation in ITU Region 1 under WRC-15 Agenda item 1.6.1 and to continue the sharing
studies with a particular attention given to the possible impact of the aggregate interference coming from all
EESS (active) systems simultaneously.
10