CEPT
ECC/CPG15
ECC
CPG PTB(2013)051
Electronic Communications Committee
3rd meeting CPG-15 PTB
Copenhagen, 21-23 August 2013
Date issued:
09 August 2013
Source:
Russian Federation
Subject:
Agenda item 1.6.1
Password protection required?
No
SHARING FEASIBILITY OF THE FIXED SATELLITE SERVICE (SPACE-EARTH)
WITH THE EARTH EXPLORATION SATELLITE SERVICE (ACTIVE) IN THE
FREQUENCY RANGE 13.25-13.75 GHZ
Summary:
This Document considers sharing feasibility of the FSS (s-E) with the EESS (active) in the
frequency band 13.25-13.75 GHz. This Document contains calculation results of interference
level from the GSO FSS satellite to active sensors on EESS satellite. The calculation results
are performed for two interference scenarios: direct interference impact and interference due
to the reflected signal.
Proposals:
РТ B Project Team is invited to consider the study results on sharing feasibility of the fixed
satellite service (space-to Earth) with the earth exploration satellite service (active) in the
frequency range 13.25-13.75 GHz and to reflect the main obtained results in Draft CEPT
Brief on Agenda item 1.6.1 (see Doc. XXX).
Background:
The frequency band 13.25-13.75 GHz is a candidate frequency band while considering
WRC-15 Agenda item 1.6. Currently Draft CPM Report (Annex 22 to Doc.242) notes that the
studies performed in the previous study periods showed limited compatibility between EESS
(active) and FSS (Earth-to-space) in the considered frequency band. The study results within
the current study period by WP4A and CEPT PT B also showed that compatibility between
the EESS (active) and FSS (Earth-to-space) is complicated. At this stage CEPT does not
support the allocation of the frequency band 13.25-13.75 GHz in uplink. However this
frequency band can be considered as a candidate one for space-to-Earth radiolink. This
Document was developed to evaluate sharing feasibility of the FSS (space-to-Earth) and
EESS (active) in the frequency band 13.25-13.75 GHz.
1. EESS (active) characteristics in the frequency band 13.25-13.75 GHz
The detailed description of EESS active sensors characteristics are presented in Section 8
of WD to PDNR ITU-R S.[R1.FSS] (Annex 5 to Doc. 4А/242). Section 8.2.1.4 contains the
protection criteria and parameters of:
- scatterometer (microwave radar, that provides information on the wind over the ocean
near the surface) including ENVISAT RA-2, QUICKSCAT SEAWINDS, HY2A, OCEANSAT2, Scatsat-1;
- Precipitation radars, including TRMM PR, GPM DPR;
- Altimeters, including SRAL, SWIM, JASON (-1,-2,-3).
In the studies the following summarized characteristics and protection criteria of EESS
satellite active sensors (Table 1) were taken into account:
Table 1
EESS(active) sensor
Orbit altitude (km)
Orbit inclination
(degrees)
Antenna type
Antenna polarization
Antenna peak gain
(dBi)
Antenna elevation
beamwidth (degrees)
Antenna azimuth
beamwidth (degrees)
Antenna beam look
angle (degrees)
Antenna scan range
(degrees)
Antenna scan period
(s)
Antenna pointing
Centre RF
frequency (GHz)
Receiver
bandwidth (MHz)
The interference
criteria
519
Altimeter
JASON-1/2/3
1 336
Scatterometer
QuickSCAT
803
Precipitation radar
TRMM/GPM DPR
350/407
97.5
66
98.2
35/65
0.9 m Parabolic
1.2 m diameter
parabolic dish
VV
Linear
39
43.9
2
1.28
2
1.28
0-10°
0
0-360°
0
0 to 360
−17 to +17 (cross
track)
5.6rpm
0
3.33 (18 rpm)
0.7
0°, 2.43°, 4°, 6°,
8° and 10°
Fixed at nadir
Circular scanning in
azimuth
13.575
13.575
13.402
320
320
0.40
1.72/3.36
−117dBW/320
MHz
−142 dBW/MHz
−117dBW/320 MHz
−142 dBW/MHz
−195 dBW/Hz
−135 dBW/MHz
−147.8 dBW/MHz
SWIM
1 m diameter
parabolic
dish
Horizontal (inner),
Vertical (outer)
41.0
1.6 (inner),
1.4 (outer)
1.8 (inner),
1.7 (outer)
40 (inner),
46 (outer)
Planar array
2.1/1.6 m
Horizontal
47.7
0.71
0.71
−17 to +17
Scanning across
nadir
track
13.796; 13.802/
13.597; 13.602
2. FSS characteristics (space-to-Earth)
The FSS satellite characteristics are taken from Annex 5 to Doc. 4А/242 in the frequency
band 10-17 GHz. The EIRP spectral density downlink is -20 dBW/Hz (40 dBW/MHz).
3. Method and calculation
The study considers two scenarios of interference signal to EESS receiver input.
1. Direct interference impact.
2. Interference due to the reflected signal.
The considered interference scenarios are shown in Fig.1.
FSS
satellite
on GSO
FSS
satellite
on GSO
≈36000 км
Scenario 1
Scenario 2
EESS
satellite
Fig.1. Interference scenarios
Scenario 1.
This scenario considers the variant of interference impact on the back lobes of EESS
antenna pattern.
The following models were used for approximation of EESS antenna pattern:
For altimeters:
JASON antenna pattern
SWIM antenna pattern
For scatterometer and precipitation radars:
QuickSCAT antenna pattern
TRMM/GPM antenna pattern
The dynamic analysis was used for interference impact from the GSO FSS satellite to the
EESS microwave radars.
The analysis results are presented for the worst case of interference impact and shown in
Table 2.
Таблица 2
Altimeter
Scatterometer
Precipitation
Параметр
SWIM
JASON-1/2/3
QuickSCAT
radar
Interference source
FSS satellite to GSO
Reference
bandwidth,
1
MHz
Peak EIRP, dBW/MHz
40
EESS satellite altitude, km
519
1336
803
350
Propagation loss, dB
207.51
206.75
207.59
206.89
Interference level at the
EESS receiver input,
-167.51
-166.75
-167.59
-166.89
dBW/MHz
Protection
criterion,
−142
−142
−135
−147.8
dBW/MHz
Margin, dB
25.5
24.75
32.6
19.1
The margin for single interference of 20 dB means that the protection criterion will not be
exceeded at least during simultaneous impact from 100 interference source with the identical
characteristics. The number of FSS satellites visible at a certain moment from NGSO EESS
satellite (with the indicated orbit parameters) will not exceed this value.
Therefore the protection criteria is met as for single and for aggregate interference
impacts as well.
Scenario 2.
This scenario considers the option when the interfering signal is reflected from the earth
surface and falls into the antenna main lobe of the EESS active sensor.
The backscattering coefficients are presented in Section 8.2.1.6 of WD to PDNR ITU-R
S.[R1.FSS] (Annex 5 to Doc. 4А/242) and are the following:
- for altimeters (antennas are in nadir direction) -1 dB;
- for precipitation radars (antenna scan range up to 17 degrees) an average backscattering
coefficient is−4 dB;
- for the scatterometer (antenna beam angles equal up to 46°) the average backscattering
coefficient is –12 dB.
In accordance with Section 8.2.1.8 of WD to PDNR ITU-R S.[R1.FSS] for the band
13.25-13.75 GHz, considering the characteristics of the EESS system, the typical reflected area
thus equals 2 000 km2(2∙109 m2). Based on it the impact from the reflected signal is considered
from one FSS satellite.
The calculations of the interference level at the receiver input of the EESS (active)
sensors are presented in Table 3.
Таблица 3
2000
Altimeter
JASON-1/2
2000
Scatterometer
QuickSCAT
2000
Precipitation
radar
2000
-122
-122
-122
-122
-1
-1
-12
-4
-30
-30
-41
-33
519
1336
1250
350
169.4
177.6
176.9
165.9
39
43.9
41.0
47.7
−142
−142
−135
−147.8
-160.4
-163.7
-176.9
-151.2
18.4
21.7
41.9
3.4
EESS(active) sensor
SWIM
Reflected area km2
FSS
ground
pfd,
dBW/(m2MHz)
Backscatter coefficient, dB
Power reflected in 1 MHz,
dBW
Distance ground – EESS
Satellite, km
Space attenuation, dB
Active
sensor
satellite
antenna gain, dBi
EESS (active) protection
level, dBW/MHz
Received power at the EESS
sensor, dBW/MHz
Margin, dB
4.Conclusion
The performed compatibility studies of the FSS (space-to-Earth) with EESS (active) in
the frequency band 13.25-13.75 GHz showed the following. In case of direct interference impact
from the FSS satellite to EESS satellite the margin of protection criterion is 25 dB for altimeters,
32 dB for scatterometers and 19 dB for precipitation radars. In case of interference due to the
reflected signal the margin of protection criterion is from 18 dB to 21 dB for altimeters, 41 dB
for scatterometers and 3 dB for precipitation radars. Taking into account the above mentioned
the compatibility of FSS (space-to-Earth) and EESS (active) in the frequency band 13.2513.75 GHz is considered to be feasible.