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7B/100-E
Radiocommunication Study Groups /Received: 9 February 2009
Subject: Question ITU-R 211/7,
WRC-11 Agenda item 1.12,
Resolution 754 (WRC-07), resolves 1 / Document 7B/100-E
9 February 2009
English only
France
PRELIMINARY DRAFT NEW REPORT ITU-R
SA.[SRS-MS(AERONAUTICAL)(37-38GHz)]
Study on compatibility between the mobile service (aeronautical) and the space research service (space-to-Earth) in the frequency band 37-38 GHz
This contribution proposes modifications to the draft new Report ITU-R SA.[SRS-MS(AERONAUTICAL)(37-38 GHz)] contained in Annex 5 to the last Chairman’s Report of Working Party 7B. The revisions are only dealing with the multiple entry analysis and are as follows:
– Suppression of Case 1 where a constant EIRP was chosen for each aircraft, as the important parameter for the protection of SRS earth stations is the pfd level at the surface of the Earth, no matter how this pfd level is met. In addition, this avoids the problem of apparent discrepancy between the pfd mask and the maximum allowed EIRP which, while well explained, may create some confusion to the reader.
– The simulations were ran using a random altitude for the aircraft instead of a constant altitude of 10 000 m, since AMS applications such as WAIC may be used also in take off and landing phases. This implies a further reduction of the pfd for low elevation angles by 6dB (–188 instead of –182 dBW/m²/Hz). The pfd for high elevation angles does not change.
– A section is added to the conclusion, analysing the impact on the EIRP level and fuselage attenuation required to satisfy this pfd mask at 90° elevation and 10 000 m for a WIFI kind of transmitter, showing that it is very difficult or even impossible in practice to meet this mask.
PRELIMINARY DRAFT NEW REPORT
ITU-R SA.[SRS-MS(AERONAUTICAL)(37-38GHz)]
Study on compatibility between the mobile service (aeronautical) and the space research service (space-to-Earth) in the frequency band 37-38 GHz
(Question ITU-R 211/7)
CONTENTS
Page
1 Introduction 5
2 Single-entry analyses 5
2.1 Single-entry narrow-band transmitter case 5
2.2 Single entry wideband transmitter case 7
2.3 Single-entry parametric power considerations 8
2.4 Interference time duration 10
2.4.1 Static and wideband considerations 10
2.4.2 Dynamic simulation – SRS lunar mission 11
2.5 Interference to the planned SRS mission ASTRO-G 14
3 Multiple entry analysis 16
3.1 Methodology summary description 16
3.2 SRS station parameters 16
3.3 Air-traffic model parameters 17
3.4 Simulation description 18
4 Conclusions 24
1 Introduction 4
2 Singleentry analyses 4
2.1 Single-entry narrow-band transmitter case 4
2.2 Single entry wideband transmitter case 6
2.3 Single-entry parametric power considerations 7
2.4 Interference time duration 9
2.4.1 Static and wideband considerations 9
2.4.2 Dynamic Simulation – SRS Lunar Mission 10
2.5 Interference to the planned SRS mission ASTRO-G 13
3 Multiple entry analysis 15
3.1 Methodology summary description 15
Page
3.2 SRS station parameters 15
3.3 Air-traffic model parameters 16
3.4 Simulation description 17
3.5 Simulation results for the constant e.i.r.p. case 18
4 Maximum power flux density permitted to meet protection criteria 20
5 Conclusions 22
FIGURES
FIGURE 1 - Aeronautical mobile interference exceeding the SRS protection criteria (narrow-band case)
(10 W/4 kHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle) 7
FIGURE 2 - Aeronautical mobile interference exceeding the SRS protection criteria (wide-band case)
(70 W/10 MHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle) 8
FIGURE 3 - Static link budget parametric analysis – aeronautical mobile interference into SRS
(minimum gain = –10 dB) 9
FIGURE 4 - Static link budget parametric analysis – aeronautical mobile interference into SRS
(maximum gain = 80 dB) 10
FIGURE 5 - Received power spectral density vs. elevation angle for the narrow-band case, with earth station antenna pointed at zenith, or at the aircraft (with maximum gain), or away from the aircraft
(with minimum gain) 11
FIGURE 6 - Percentage of time exceeding interference criteria vs e.i.r.p. (aircraft altitude = 12km, SRS lunar mission) 13
FIGURE 7 - Aircraft e.i.r.p. vs. range while meeting Recommendation ITU-R SA.1396 (aircraft altitude
= 12km, SRS lunar mission) 13
FIGURE 8 - SRS station antenna pattern 17
FIGURE 9 - Air-routes considered for simulation 18
FIGURE 10 - Pfd mask to be met by each AMS transmitter at each SRS earth station 23
FIGURE 11 - Interference power (dBW/Hz) for one single experiment 24
Aeronautical mobile interference exceeding the SRS protection criteria (narrow-band
case) (10 W/4 kHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle) 6
FIGURE 2 - Aeronautical mobile interference exceeding the SRS protection criteria (wide-band
case) (70 W/10 MHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle) 7
FIGURE 3 - Static Link Budget Parametric Analysis – Aeronautical Mobile Interference into SRS (minimum gain = -10 dB) 8
FIGURE 4 - Static Link Budget Parametric Analysis – Aeronautical Mobile Interference into SRS (maximum gain = 80 dB) 9
FIGURE 5 - Received power spectral density vs. elevation angle for the narrow-band case, with
earth station antenna pointed at zenith, or at the aircraft (with maximum gain), or away from the
aircraft (with minimum gain) 10
Page
FIGURE 6 - Percentage of Time Exceeding Interference Criteria vs e.i.r.p.
(Aircraft Altitude = 12km, SRS Lunar Mission) 12
FIGURE 7 - Aircraft e.i.r.p. vs. Range while meeting Recommendation ITU-R SA.1396
(Aircraft altitude = 12km, SRS Lunar mission) 12
FIGURE 8 - SRS station antenna pattern 16
FIGURE 9 - Air-routes considered for simulation 17
FIGURE 10 - Interference power (dBW/Hz) for one single experiment (e.i.r.p. = 0 dBW/MHz) 19
FIGURE 11 - Percentage of time the criterion is exceeded vs e.i.r.p. 20
FIGURE 12 - Pfd mask to be met by each AMS transmitter at each SRS earth station 21
TABLES
TABLE 1 - Typical slant ranges from an earth station 5
TABLE 2 - Narrow-band aeronautical mobile interference to space research service (10 W/4 kHz,
12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle) 6
TABLE 3 - Simulation parameters 12
TABLE 4 - Interference from AMS transmitter into ASTRO-G downlink at 37-38 GHz 15
1 Introduction
Space research earth station receivers operating in the 37-38 GHz band have very low thresholds. To protect these stations (deep space and near Earth included) from interference, the ITU-R has published protection criteria in Recommendation. ITU-R SA.1157.
The analyses in Section 2 show that since the range of an aeronautical mobile transmitter is much less than the range of space research missions (see Table 1), interference from an aeronautical transmitter to a space research earth station receiver can significantly exceed the ITU-R protection criteria.
TABLE 1
Typical slant ranges from an earth station
Slant range / Relative inversesquare loss
(km) / (dB)
Aircraft at 12 km altitude 60 deg elevation / 14 / 0
LEO at 300 km altitude, 15 deg elevation / 1 400 / 40
GEO / 33 000 / 67
Deep space mission at minimum distance / 2 000 000 / 102
Presently, the frequency allocation tables in ITU Radio Regulations have already excluded aeronautical mobile in the frequency bands 2.29-2.3 GHz, 8.4-8.5 GHz, 22.21-22.5 GHz and 31.531.8 GHz, where the mobile service is co-allocated with the space research service.
2 Single-entry analyses
The interference from aeronautical mobile to the space research earth stations is analyzed for anarrow-band and a wide-band transmitter.
2.1 Single-entry narrow-band transmitter case
Recommendation ITU-R SA.1016 provided an example of an assumed narrow band aeronautical mobile transmitter interfering with a space research earth station (space-to-Earth) (deep space) at frequencies up to 32 GHz. Given an aircraft transmitter with maximum e.i.r.p. PSD of 10dB(W/4kHz), antenna gain of 0 dBi, and altitude of 12 km, the results in Recommendation ITURSA.1016 (Annex 1, Table 3) showed that the aircraft signals received by the space research earth station would exceed the deep space protection criterion given in Recommendation ITURSA.1157 by 35dB at 2.3 GHz, 22.1 dB at 8.4 GHz, 17.9 dB at 13 GHz and 6.9 dB at 32GHz. In these previous analyses, the airborne transmitter was at 0-degree elevation relative to the space research earth station. Furthermore, the space research earth station antenna was assumed to have a -10 dB gain in the direction of the aircraft, corresponding to aboresight separation angle of at least 48 degrees (Recommendation ITU-R SA.509). These results therefore represent minimum interference.
It is more common that the aircraft is at 60-degree elevation angle from the victim earth station and is at 20-degree cone angle off the antenna boresight. The link analysis given in Table 2 indicates that the interferences, in this case, will be 39 dB stronger than the minimum interference case discussed above. These interferences far exceed the protection criterion of space research earth stations for deep space and near earth missions.
TABLE 2
Narrow-band aeronautical mobile interference to space research service
(10 W/4 kHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle)
Transmitter power (dBW) / 10 / 10 / 10 / 10 / 10
Bandwidth containing the power (dB-Hz) / 36 / 36 / 36 / 36 / 36
Aircraft antenna gain toward victim (dBi) / 0 / 0 / 0 / 0 / 0
Aircraft e.i.r.p. (dBW) / 10 / 10 / 10 / 10 / 10
Maximum transmitted PSD (dBW/Hz) / -26 / -26 / -26 / -26 / -26
Altitude (km) / 12 / 12 / 12 / 12 / 12
Elevation (deg) / 60 / 60 / 60 / 60 / 60
Slant range (km) / 14 / 14 / 14 / 14 / 14
Carrier frequency (GHz) / 2.3 / 8.4 / 13 / 32 / 38
Wave length (mm) / 130 / 36 / 23 / 9 / 8
Space loss (dB) / -122.6 / -133.8 / -137.6 / -145.5 / -147
Victim antenna gain toward interferer (dBi) / 0 / 0 / 0 / 0 / 0
Maximum received PSD (dBW/Hz) / -148.6 / -159.8 / -163.6 / -171.5 / -173
Deep space protection criterion (dBW/Hz) / -222 / -220 / -220 / -216 / -217
Near earth protection criterion (dBW/Hz) / -216 / -216 / -216 / -216 / -217
Max received PSD above SRS deep space protection criterion (dB) / 73.4 / 60.2 / 56.4 / 44.5 / 44
Max received PSD above SRS near earth protection criterion (dB) / 67.4 / 56.2 / 52.4 / 44.5 / 44
In Table 2, the link analyses given in Recommendation ITU-R SA.1016 were extended to the 3738GHz shared band, based on the same transmitter e.i.r.p. PSD of 10 dB(W/4 kHz) and using the 37-38 GHz space research protection criterion (Recommendation ITU-R SA.1396). The results, plotted in Figure 1, show that the interference levels will exceed the space research deep space and near earth protection criterion by at least 44 dB.
FIGURE 1
Aeronautical mobile interference exceeding the SRS protection criteria (narrow-band case)
(10 W/4 kHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle)
2.2 Single entry wideband transmitter case
An example of possible airborne transmission of wide-band signals with 10 MHz bandwidth, atcarrier frequencies in the range of about 10 to 40 GHz, and with transmitter power of 70 Watts, was considered. The maximum e.i.r.p. PSD for this example is calculated to be 18.5 dB(W/10 MHz). Compared with the 10 dB(W/4 kHz) e.i.r.p. PSD of the narrow-band case, the wideband example has an e.i.r.p. PSD 25.5 dB/Hz weaker. Under the same geometry of Table 2, the interference levels will also be 25.5 dB/Hz weaker at the victim’s receiver, but the minimum interference will still be 18.5dB above the protection criteria. These results are plotted in Fig.2.
FIGURE 2
Aeronautical mobile interference exceeding the SRS protection criteria (wide-band case)
(70 W/10 MHz, 12-km altitude, 0-dBi gain, 60-deg elevation, 20-deg cone angle)
[Editor’s note: Further studies taking into account low-power transmitters might be submitted at alater stage.]
2.3 Single-entry parametric power considerations
To bound the extent of the sharing situation, it is necessary to calculate the best and worst case sharing scenarios. It is possible to calculate the interference power received at an SRS earth station by using the free space loss and the minimum gain of the SRS earth-station antenna, resulting in abest case sharing scenario. By calculating this interference power received at different aircraft transmitter e.i.r.p. levels as a function of slant range, it is possible to determine the maximum e.i.r.p. allowed from the aircraft to satisfy the interference criteria. These results are in Fig.3.
Figure 3
Static link budget parametric analysis – aeronautical mobile
interference into SRS (minimum gain = –10 dB)
The maximum altitude of a typical aircraft is 12km. If an aircraft is flying at an altitude of 12km, the minimum slant range would be 12 km, resulting in a maximum aircraft e.i.r.p. of −60 dBW/Hz emanating from the aircraft. However, this best case sharing scenario does not take into account the aircraft interfering with the earth station’s main beam. In practice, SRS earth stations may track satellites in near earth orbit, lunar orbit, or deep space missions, resulting in a wide variety of antenna pointing angles, and aircraft may fly in any number of directions, altitudes and speeds. Under these circumstances, it is reasonable to assume that the aircraft may interfere with any portion of the SRS earth station antenna, making it necessary to include an analysis of the main lobe. Assuming an antenna gain of 80 dB, the previous static link analysis is repeated. Results of this analysis are provided in Fig.4.
Figure 4
Static link budget parametric analysis – aeronautical mobile
interference into SRS (maximum gain = 80 dB)
While an e.i.r.p. of −60 dBW/Hz emanating from an aircraft ’s e.i.r.p. of −60 dBW/Hz is acceptable for the back lobe, the power level received in the front lobe exceeds the interference criteria by 90dB. Purely on a static basis, in order to completely satisfy the interference power requirement for the earth station’s main lobe, an aircraft e.i.r.p. of −150 dBW/Hz must not be exceeded, at an aircraft’s maximum altitude of 12 km. Aircraft operating lower than a 12km altitude will need lower e.i.r.p. emissions to meet the interference criteria in both the earth station’s main and back lobes. Since aircraft position and SRS earth-station antenna pointing direction are both changing dynamically, the limit of aircraft’s e.i.r.p. should be determined statistically.