1、 Rec. ITU-R M.1747 1 RECOMMENDATION ITU-R M.1747*Protection of the Earth exploration-satellite service (EESS) (passive) in the band 1 400-1 427 MHz from unwanted emissions of MSS feeder links that may operate in the bands 1 390-1 392 MHz (Earth-to-space) and 1 430-1 432 MHz (space-to-Earth) (2006) S
2、cope This Recommendation provides unwanted emission power levels for the protection of EESS (passive) satellites operating in the band 1 400-1 427 MHz from MSS feeder links (space-to-Earth) that may operate in the band 1 430-1 432 MHz and MSS feeder links (Earth-to-space) that may operate in the ban
3、d 1 390-1 392 MHz. The ITU Radiocommunication Assembly, considering a) that WRC-03 made a provisional allocation on a secondary basis to the FSS for MSS feeder links through No. 5.339A in the bands 1 390-1 392 (Earth-to-space) and 1 430-1 432 MHz (space-to-Earth); b) that these allocations are limit
4、ed to use by feeder links for non-geostationary-satellite networks in the mobile-satellite service with service links below 1 GHz, and Resolution 745 (WRC-03) applies; c) that the band 1 400-1 427 MHz is allocated to the Earth exploration-satellite service (EESS) (passive), radio astronomy and space
5、 research (passive) services on a primary basis in all Regions and that No. 5.340 also applies to the band 1 400-1 427 MHz; d) that Resolution 745 (WRC-03) calls for compatibility studies, including the measurement of emissions from equipment that would be employed in operational systems, to validat
6、e that the MSS systems using this band meet all requirements for the protection of passive services in the band 1 400-1 427 MHz; e) that the band 1 400-1 427 MHz is most suitable for EESS (passive) for the measurement of soil moisture, sea surface salinity and vegetation biomass; f) that Recommendat
7、ion ITU-R RS.1029 contains the protection criteria for the EESS (passive); g) that Recommendation ITU-R M.1184 provides technical characteristics of mobile-satellite systems in frequency bands below 3 GHz for use in developing criteria for sharing between the mobile-satellite service (MSS) and other
8、 services; h) that studies for MSS feeder links (Earth-to-space) as contained in Annexes 1 and 2 concluded that the most suitable criterion to protect EESS (passive) would be an unwanted power spectral-density specification applicable to MSS feeder-link stations in the band 1 400-1 427 MHz; *This Re
9、commendation was jointly prepared by Radiocommunication Study Groups 7 and 8 and any future revision will also be undertaken jointly. 2 Rec. ITU-R M.1747 j) that a margin of around 2 dB is advisable on top of the results obtained for an interference probability of 0.05% to account for the fact that
10、only a limited number of feeder-link and passive sensor combinations could be studied and that actual MSS characteristics may deviate slightly from the ones assumed in the studies, noting a) that the reduction of unwanted emissions to levels required for adequate protection of passive services in th
11、e band 1 400-1 427 MHz is feasible with baseband processing techniques for typical combinations of data rates and modulation techniques without a specific post amplifier filter; b) that an additional post amplifier filter can be used in cases where the baseband processing referred to under noting a)
12、 is not sufficient to meet the required unwanted emission levels; c) that the unwanted emission level at the input to the MSS feeder-link satellite antenna required to protect the RAS is below the level given in recommends 1 (see Recommendation ITU-R M.1748, recommends 1 that, in order to protect th
13、e Earth exploration-satellite (passive) service in the band 1 400-1 427 MHz, unwanted emissions of MSS feeder links should not exceed the following power levels in the band 1 400-1 427 MHz: 63 dBW at the input to the earth station antenna for MSS feeder links (Earth-to-space) operating in the band 1
14、 390-1 392 MHz; 46 dBW at the input to the satellite antenna for MSS feeder links (space-to-Earth) operating in the band 1 430-1 432 MHz. Annex 1 Protection of the Earth exploration-satellite service (passive) sensors in the band 1 400-1 427 MHz from mobile-satellite service feeder links that may op
15、erate in the FSS around 1 400 MHz 1 Technical characteristics of the EESS passive sensor satellite Frequencies near 1 400 MHz are most suitable for measuring soil moisture, sea surface salinity and vegetation biomass. NASA is currently developing an instrument for measuring sea surface salinity (the
16、 Aquarius mission) which will collect measurements in the entire passive microwave band under consideration (1 400 to 1 427 MHz). NASA is also developing an instrument for measuring soil moisture (the HYDROS mission) in the 1 400 to 1 427 MHz band. The technical characteristics of the Aquarius and H
17、YDROS passive sensing satellites are presented in Table 1. The Aquarius science goals are to observe and model the processes that relate salinity variations to climatic changes in the global cycling of water, and to understand how these variations influence the general ocean circulation. The HYDROS
18、science goal is to measure soil moisture which is a key variable in the hydrologic cycle with significant influence on evaporation, infiltration and runoff. Rec. ITU-R M.1747 3 TABLE 1 Aquarius and HYDROS passive sensor parameters Parameter Aquarius HYDROS Peak antenna gain (for each beam) 31.1 dBi
19、35 dBi 3 dB beamwidth (for each beam) 5.5 2.6 Antenna polarization Horizontal and vertical Horizontal and vertical Beam 1 Cross track: 37.2 Along track: 4.8 Beam 2 Cross track: 28.9 Along track: 9.5 Antenna pointing (degrees from nadir) Beam 3 Cross track: 20.7 Along track: 4.8 40 off-nadir Antenna
20、scans about nadir at 6 rpm with a sampling time of 72 ms/cell Orbit 600 km altitude 98 inclination 670 km altitude 98 inclination Receiver bandwidth (3 dB) 25 MHz 27 MHz Permissible interference level 174 dB(W/27 MHz) 174 dB(W/27 MHz) Percentage of time interference may be exceeded 0.1% 0.1% HYDROS
21、uses a scanning antenna at a 40 degree offset from nadir. The gain pattern for the HYDROS antenna is illustrated in Fig. 1. Aquarius uses a three-beam push-broom radiometer configuration with each sensor beam having a gain pattern similar to HYDROS. Each beam represents a single pixel with an averag
22、e integration time of 10 s. FIGURE 1 HYDROS antenna pattern 4 Rec. ITU-R M.1747 2 Technical characteristics of the MSS system The 1 390-1 392 MHz and 1 430-1 432 MHz bands are under consideration for feeder links between non-geostationary mobile-service satellites and fixed earth stations located wo
23、rldwide. These feeder links would transmit data to and receive data from a constellation of MSS satellites. In addition, telemetry, tracking and command functions would be carried out via these links. Four MSS constellations comprising 128 satellites were considered in this study as shown in Table 2
24、. The parameters for constellations “L”, “M”, “Q”, and “S” were obtained from Annex 2 of Recommendation ITU-R M.1184. A slight modification was made to the number and inclination of the satellites in the “Q” constellation in order to make this constellation consistent with actual planned systems. Th
25、e number of satellites composing the “Q” constellation was reduced from 32 to 26 for this study and the inclination for 24 of the 26 satellites was increased from 51 to 66 degrees. TABLE 2 MSS constellation characteristics Recommendation ITU-R M.1184 Constellation L Constellation M Constellation S C
26、onstellation Q(1)Number of satellites 48 48 6 26 Altitude (km) 950 825 775 692 1 000 Inclination (degrees) 50 45 0 70, 108 98 66 83 Orbit planes 8 3 1 2 2 6 2 Satellites per plane 6 8 3 4 1 (1)The number of satellites composing the “Q” constellation was reduced from 32 to 26 for this study and the i
27、nclination for 24 of the 26 satellites was increased from 51 to 66 for consistency with the constellation used in Document 7C/8. The MSS Earth-to-space and space-to-Earth feeder-link characteristics used for this study are described in Tables 3 and 4, respectively. Feeder-link characteristics were a
28、ssumed to be identical for the four MSS constellations, and were obtained from previous ITU-R sharing studies. The pattern on the left in Fig. 2 illustrates the gain pattern of the non-GSO MSS satellite circularly polarized feeder-link antenna used in this analysis for both transmit and receive. The
29、 pattern on the right in Fig. 2 illustrates the gain pattern of the MSS earth station antenna. This pattern is taken from Appendix 8, Annex III of the Radio Regulations. Each MSS constellation is supported by 15 earth stations distributed throughout the world in representative locations, resulting i
30、n a total of 60 earth stations. TABLE 3 Earth-to-space feeder-link characteristics Parameter Value Number of earth stations 15 per MSS constellation, 60 total Earth station locations Distributed throughout the world for each constellation Rec. ITU-R M.1747 5 Transmit antenna peak gain 30 dBi 3 dB be
31、amwidth 5 Gain floor 1.5 dBi Antenna pattern RR Appendix 8, Annex III Antenna polarization Right hand circular Antenna pointing Tracks nearest satellite at elevations between 5 and 90 Transmit power 10 Watts per 100 kHz Line loss 1 dB Modulation GMSK(1), OQPSK(2), 8-PSK(2), 16-QAM(2)Channel bandwidt
32、h 100, 300, 855 kHz (1)Gaussian baseband filtered with BTb= 0.5. (2)Square root raised cosine baseband filtered with BTs= 1.0. TABLE 4 Space-to-Earth feeder-link characteristics Parameter Value Transmit antenna peak gain See Fig. 2 Gain floor 6 dB Antenna polarization Right hand circular Antenna poi
33、nting Fixed, approx. 4 000 km diameter coverage area Transmit power 1 Watt per 100 kHz Line loss 1 dB Modulation GMSK(1), OQPSK(2), 8-PSK(2), 16-QAM(2)Channel bandwidth 100, 300, 855 kHz (1)Gaussian baseband filtered with BTb= 0.5. (2)Square root raised cosine baseband filtered with BTs= 1.0. 6 Rec.
34、 ITU-R M.1747 FIGURE 2 Non-GSO MSS satellite receive and transmit antenna pattern (left) and Earth station receive and transmit antenna pattern (right) 3 Interference analysis 3.1 Overview The dynamic interference model includes four MSS systems comprising 128 spacecraft and 60 earth stations. The s
35、imulation model calculated the cumulative distribution functions (CDFs) of co-channel interference power produced by an aggregate of an individual MSS systems uplinks and downlinks, and an aggregate of all MSS systems uplinks and downlinks at the passive sensor receiver input. At each step of the si
36、mulation, the model calculated the aggregate power at the output of a single sensor antenna beam produced by all visible and active MSS uplinks and downlinks, and these results were sorted into bins of 1.0 dB resolution for use in plotting the CDF. The simulations used one second time-steps for Aqua
37、rius and 50 ms time-steps for HYDROS to ensure adequate overlap with the sampling time per cell of the sensor beams. The simulations were run corresponding to a period of 14 days in real time. The interference power level I (dBW) at the output of the passive sensor antenna was calculated using the f
38、ollowing equation: ()atmrttLLGRfGLPI pl += )log(2044.32log10 (1) where: tP : interferer transmitter power (W) lL : transmitter line loss tG : interferer antenna gain in direction of victim station (dBi) f : victim station receive frequency (MHz) R : slant range between interferer and victim station
39、(km) rG : victim station antenna gain in direction of interferer (dBi) pL : polarization discrimination loss atmL : atmospheric absorption loss (dB). Rec. ITU-R M.1747 7 A value of 0 dB was used for attenuation due to atmospheric absorption (dry air and water vapour). A value of 1.4 dB was used for
40、the polarization discrimination loss resulting from a linearly polarized passive sensor antenna and a circularly polarized MSS antenna. These calculations assumed that all of the MSS links operate on the same frequency and are within the passive sensor bandwidth. All simulations were performed at a
41、frequency of 1 400 MHz and used transmit power levels associated with a 100 kHz channel bandwidth. It should be noted that CDF plots for 300 kHz and 855 kHz channel bandwidths would indicate higher interference levels due to scaling of the Earth-to-space and space-to-Earth link transmit power levels
42、 as a function of channel bandwidth. In order to determine the out-of-band power from MSS feeder links in the 1 400-1 427 MHz band, modelling and simulation techniques were employed for various modulation schemes and channel bandwidths. The simulation model was first validated against the GMSK hardw
43、are measurement data, and then power spectral-density (PSD) data was generated via simulation for other modulation techniques and channel bandwidths. Using the PSD data, total integrated power relative to 1 W in the 1 400-1 427 MHz band was determined from an MSS uplink and downlink transmitter. The
44、se results are provided in Table 5. The centre frequencies for the simulated uplink and downlink signals were chosen so that the first null of the modulated signal occurred at the MSS feeder-link band edge closest to the EESS (passive) band. TABLE 5 Total power in 1 400-1 427 MHz band from a possibl
45、e worst case MSS feeder-link transmitter assuming 1 W transmit power (dBW) Feeder-link modulation Uplink (1 390-1 392 MHz) Downlink (1 430-1 432 MHz) Feeder-link channel bandwidth GMSK OQPSK 8-PSK 16-QAM GMSK QPSK 8-PSK 16-QAM 100 kHz 75.0 74.3 74.4 74.4 71.5 71.8 71.8 71.9 300 kHz 74.1 73.5 73.6 73
46、.6 72.2 71.0 71.2 71.6 855 kHz 75.0 75.1 73.1 73.5 71.3 70.8 59.1 64.2 3.2 Analysis results operational mode Cumulative distribution function (CDF) plots for Aquarius are shown in Figs. 3 through 5. Similar CDF plots were obtained for HYDROS, and therefore are not shown. The CDF for the Earth-to-spa
47、ce link co-channel interference power level at Aquarius is plotted in Fig. 3 for each MSS system. Figure 4 shows the Aquarius co-channel CDF plot for each MSS system space-to-Earth link. Figure 5 shows the aggregate co-channel CDF plot for all MSS Earth-to-space links, the aggregate co-channel CDF p
48、lot for all MSS space-to-Earth links, and the total aggregate co-channel CDF plot for all MSS links and systems that may interfere with Aquarius. It is the view of both WP 8D and WP 7C that the MSS feeder links should not contribute more than 5% to 10% to the total permissible interference, taking i
49、nto account that several services contribute to the total permissible interference specified in Recommendation ITU-R SA.1029, and the potential allocation status of the MSS feeder links. 8 Rec. ITU-R M.1747 FIGURE 3 Aquarius CDFs for co-channel interference into passive sensors from MSS Earth-to-space links (100 kHz channel bandwidth) FIGURE 4 Aquarius CDFs for co-channel interference into passive sensors from MSS space-to-Earth links (100 kHz channel bandwidth) Rec. ITU-R M.1747 9 FIGURE 5 Aquarius aggregate CDFs for co-channel in
