1、 Rec. ITU-R SA.1158-3 1 RECOMMENDATION ITU-R SA.1158-3*Feasibility of frequency sharing in the 1 670-1 710 MHz band between the meteorological-satellite service (space-to-Earth) and the mobile-satellite service (Earth-to-space) (Question ITU-R 204/7) (1995-1997-1999-2003) The ITU Radiocommunication
2、Assembly, considering a) that the World Administrative Radio Conference for Dealing with Frequency Allocations in Certain Parts of the Spectrum (Malaga-Torremolinos, 1992) (WARC-92) has allocated the 1 675-1 710 MHz band on a primary basis in Region 2 to the mobile-satellite service (MSS) (Earth-to-
3、space) and maintained the primary status of the meteorological-satellite (MetSat service) service (space-to-Earth); b) that each of these two services may be provided by GSO satellite systems and non-GSO satellite systems; c) that MetSat operators have agreed to separate the band 1 670-1 710 MHz int
4、o four sub-bands which are being used and are expected to continue to be used as follows: 1 670-1 683 MHz: main earth stations at fixed locations for reception of raw image data, data collection data and spacecraft telemetry from GSO meteorological satellites; 1 683-1 690 MHz: main earth stations at
5、 fixed locations for reception of raw image data, data collection and spacecraft telemetry from GSO meteorological satellites; user stations for direct readout from GSO meteorological satellites (GVAR and S-VISSR) (see Note 1); 1 690-1 698 MHz: user stations for direct readout services from GSO mete
6、orological satellites; 1 698-1 710 MHz: user stations for direct readout services and prerecorded image data at main earth stations from non-GSO meteorological satellites; d) that the 1 670-1 690 MHz band is and will continue to be used primarily but not exclusively by a limited number of main meteo
7、rological earth stations (command and data acquisition (CDA) and the 1 683-1 690 MHz part of the band is and will continue to be used also by direct readout user stations (GVAR and S-VISSR); e) that the portion 1 670-1 675 MHz of the band is used by very few main MetSat earth stations; f) that there
8、 exist thousands of MetSat earth stations in the 1 690-1 710 MHz band, many of them using small antennas; *This Recommendation should be brought to the attention of the World Meteorological Organization (WMO) and Radiocommunication Study Group 8 (WP 8D). 2 Rec. ITU-R SA.1158-3 g) that for different
9、functions provided by the MetSat service, meteorological earth stations in the 1 690-1 710 MHz band and in the 1 683-1 690 MHz band can be fixed, mobile or transportable; h) that Recommendation ITU-R SA.1027 provides sharing criteria for current MetSat systems using satellites in low-Earth orbit (LE
10、O); j) that Recommendation ITU-R SA.1161 provides sharing criteria for current MetSat systems using GSO satellites; k) that MSS earth station transmitters are expected to be deployed near or within a MetSat service area; l) that some operators of meteorological satellites plan to increase the channe
11、l bandwidths and revise the frequency assignment plans for new MetSat generations, which would make interleaving of meteorological and mobile-satellite channels impracticable; m) that GSO MetSat space stations, which initially serve a certain area, may be relocated from time to time in order to prov
12、ide coverage of another area; n) that Annexes 1, 2, 3 and 4 provide a view pertaining to the technical sharing aspects of the MetSat and MSS services operating in the 1 670-1 710 MHz band; o) that mobile-satellite techniques are either available or may be able to be developed to automatically and dy
13、namically avoid transmissions from earth stations in the vicinity of receiving MetSat earth stations and that such techniques are described in Annex 3, recognizing 1 that No. 5.377 of the Radio Regulations (RR) states that, in the band 1 675-1 710 MHz, stations in the MSS shall not cause harmful int
14、erference to, nor constrain the development of, the MetSat and meteorological aids services and that the use of this band shall be subject to coordination under RR No. 9.11A; 2 that studies (see Annex 1) have indicated that potential interference to meteorological earth stations from co-frequency MS
15、S earth stations would be acceptable when the meteorological earth stations are protected by exclusion zones with radii of up to several hundred kilometres and appropriate technical measures are employed to avoid transmissions by mobile earth stations within the respective exclusion zones; 3 that th
16、e control of the mobile earth stations (MES) could be achieved with a location determination system forming part of the mobile-satellite system; this location determination may require a narrow-band signalling channel transmitted from the MES to the mobile satellite; 4 that studies indicate that int
17、erference from mobile-satellite service (MSS) earth station emissions in the band 1 670-1 675 MHz to meteorological earth stations would be acceptable with limited restrictions on MSS operations; 5 that studies conclude the complex challenge of MSS sharing in the band 1 683-1 690 MHz with the increa
18、sing number of GVAR and S-VISSR stations (see Note 1), especially transportable and future stations, would be extremely difficult; 6 that sharing in the band 1 690-1 710 MHz would not be feasible in view of the large number of MetSat earth stations, their generally unknown locations and the increasi
19、ng use of the service, Rec. ITU-R SA.1158-3 3 recommends 1 that MES possibly operating in part of the 1 670-1 690 MHz band do not transmit, except on a narrow-band signalling channel, inside the exclusion zones around main meteorological earth stations (CDA and primary data users station (PDUS), tak
20、ing into consideration the radii identified in recognizing 2, increased by the precision (km) of the position determination system referred to in recognizing 3 (see Note 2); 2 that mobile-satellite systems be equipped with demonstrated location determination capability, permitting the determination
21、of the position of the mobile earth stations, in order to assure compliance with recommends 1; 3 that the narrow-band signalling channel, which may be required worldwide by certain location determination systems, be assigned in agreement with the meteorological operators concerned; 4 that the MSS co
22、uld share the band 1 670-1 675 MHz with the MetSat service based on minor restrictions to ensure no worldwide impact on MetSat operations in the band 1 670-1 710 MHz. NOTE 1 GOES stands for geostationary operational environmental satellite; GVAR stands for GOES variable; VISSR stands for visual and
23、infrared spin scan radiometer; S-VISSR stands for stretched VISSR; NOTE 2 The WMO is invited to inform the ITU, at regular intervals, of the geographical position of main meteorological earth stations. Annex 1 Sharing analysis between the MetSat service and the MSS in the frequency bands 1 670-1 675
24、 MHz and 1 683-1 690 MHz 1 Introduction The ITU-R conducted an extensive series of studies regarding the potential sharing situation between the MSS and the MetSat service in the band 1 683-1 690 MHz or in the vicinity of this band. The band 1 683-1 690 MHz is mainly used by three different types of
25、 meteorological earth stations. While there are only a limited number of main MetSat earth stations deployed in all three ITU Regions, there are a large number of meteorological earth stations operated in Regions 2 and 3 and the locations of many of these stations are unknown. Some of them are also
26、mobile (on ships and trucks) or transportable. During WRC-2000, it was also acknowledged that there is an increase in use of these stations in Regions 2 and 3 and that potential MSS operation should not constrain current and future development of the MetSat service as specified in RR No. 5.377. Rega
27、rding meteorological earth stations, main stations with antenna diameters up to 15 m as well as data user stations such as GVAR and S-VISSR are operating in the band 1 683-1 690 MHz. Only a limited number of main stations operates in the band 1 670-1 675 MHz. Sharing and interference criteria for sp
28、ace-to-Earth data transmission systems in the Earth exploration-satellite and MestSat services have been established in a number of ITU-R Recommendations. RR Appendix 7 and Recommendation ITU-R SA.1160 can be used for reference. 4 Rec. ITU-R SA.1158-3 Recommendation ITU-R M.1184 provides information
29、 on mobile-satellite system characteristics to be used in sharing studies with other primary services in the range 1-3 GHz. As the interference to the MetSat stations is primarily determined by the amount of energy radiated towards the horizon and the troposphere, some degree of antenna discriminati
30、on will occur. Unless the MSS terminal actually operates at low elevation angles, the overall effect will be very similar to the systems using omnidirectional antennas. It has therefore been assumed that the mobile terminals operate in a way which results in very low gain around 0 dBi towards the ho
31、rizon. In view of the enormous differences that can arise from considering best and worst cases, it has been agreed between the relevant Radiocommunication Working Parties to use MSS, MetSat and shielding characteristics which disregard best and worst cases but consider a more representative typical
32、 sharing situation with some deviations to favourable and unfavourable sharing situations. The required separation distances are to a significant extent a function of the elevation angle and terrain shielding. The elevation angle ranges between 3 and 90 for stations receiving data from GSO satellite
33、s. Main stations will not operate at elevation angles of less than 5. Shielding for main stations is in general quite good because of typical deployment in remote locations. However, user stations are often deployed on top of buildings with an unobstructed view of the surroundings. 2 System characte
34、ristics assumed for the analyses The characteristics shown in Table 1 have been adopted to represent a range of MSS and MetSat systems. The parameter values have been chosen to represent favourable, typical and unfavourable sharing conditions, and do not necessarily represent the best-case or worst-
35、case conditions. TABLE 1 System parameters used in sharing studies between the MetSat service and the MSS Favour-able sharing case Typical sharing, Case 1 Typical sharing, Case 2 Unfavourablesharing case MSS characteristics Maximum e.i.r.p. per channel (dBW) 3.5 21 17 10.9 Maximum antenna gain (dBi)
36、 0 16.5 10 Not applicable Channel data rate (kbit/s) 23.4 732 5.6 4.5 Allocated bandwidth (channel spacing) (kHz) 31.24 200 12.5 6 Average antenna gain towards horizon (dBi) 1 0 0 0 Average e.i.r.p. towards horizon (dBW) 3.5 4.5 7 6.9 Average e.i.r.p. density towards horizon (dB(W/4 kHz) 5.4 12.5 2.
37、1 5.1 Antenna height of MES above ground level (m) 2 2 2 10 Rec. ITU-R SA.1158-3 5 TABLE 1 (end) Favour-able sharing case Typical sharing, Case 1 Typical sharing, Case 2 Unfavourablesharing case MSS characteristics (Cont.) Average obstacle height in vicinity of MES (m) 90 50 50 10 Distance of obstac
38、le to MES (km) 10 10 10 5 Satellite beamwidth (degrees) 0.7 1.5 7 2 Percentage of transmitting MES (%) 60 75 75 90 Polarization discrimination (dB) 3 3 3 3 MetSat characteristics for main stations Antenna diameter (m) 15 15 15 Antenna centre height above ground level (m) 15 20 25 Minimum antenna ele
39、vation angle (degrees) 20 15 10 Permissible long-term interference level (20%) (dB(W/4 kHz) 182 182 182 Permissible short-term interference level (dB(W/4 kHz) 178 178 178 Percentage of time for short-term interference(1)(%) 0.011 0.011 0.011 Receiver bandwidth (kHz) 5 200 5 200 30 Obstacle height in
40、 vicinity of main station (m) 200 150 25 Distance of obstacle to main station (km) 10 10 10 Typical radio climatic zone for main station A2 A2 A1 MetSat characteristics for user stations Antenna diameter (m) 3.6 3.6 3.6 Antenna centre height above ground level (m) 5 25 50 Minimum antenna elevation a
41、ngle (degrees) 20 15 5 Permissible long-term interference level (dB(W/4 kHz) 180 180 180 Permissible short-term interference level (dB(W/4 kHz) 175.3 175.3 175.3 Percentage of time for interference (%) 0.025 0.025 0.025 Receiver bandwidth (kHz) 6 000 4 200 4 200 Obstacle height in vicinity of user s
42、tation (m) 50 25 0 Distance of obstacle to user station (km) 10 10 Not applicable Typical radio climatic zone for user station A2 A1 A1 (1)This percentage applies to the aggregate interference from all MES. 6 Rec. ITU-R SA.1158-3 Combinations of the above system assumptions should be considered. For
43、 studies addressing adjacent band interference, Recommendation ITU-R SA.1160 shall be taken into account regarding protection criteria for small user stations with antenna diameters between 1.2 and 2.4 m. For out-of-band emissions of MES terminals, Recommendation ITU-R M.1480 shall be referred to. 3
44、 Analysis methodology 3.1 MES density This section presents an analysis where, based on system parameters, a number of operating MESs are considered. Therefore, the MES distribution and density must be calculated for each of the sharing cases. The first step in the analysis is to determine the size
45、of the spot beam projected on the Earths surface. For simplicity, it will be assumed that the spot beam centreline is perpendicular to the Earths surface and the surface area within the spot beam is approximately flat. Adjacent spot beams will overlap. To further simplify the analysis, the area of e
46、ach spot beam will be converted to a regular hexagon. This can be done since either spot beam can service an MES within the overlap area (refer to Fig. 1). For the MES density calculation, the overlap areas may be divided evenly between the overlapping beams. 1158-01Adjacent spot beamsEffective spot
47、 beamhexagonal areaFIGURE 1Conversion of circular spot beams to effectively equal hexagonal areasThe area of the hexagon is given by: 2/)33()2/tan(2= hA where: h : GSO altitude (km) : spot beamwidth (degrees). Rec. ITU-R SA.1158-3 7 TABLE 2 Effective square area of spot beams on Earths surface for c
48、ases listed in Table 1 The next step is to determine the MES density within the service area under consideration (analysis area). Since the spot beams are smaller or nearly equal to the exclusion zone sizes, the required analysis area is larger than the spot beam footprints. All three sharing cases
49、defined in Table 1 provide the receive antenna beamwidth (satellite beamwidth), the channel spacing (allocated bandwidth) and the system loading factor (percentage of transmitting MES). From these values the transmitting MES density can be calculated. The transmitting MES density can then be used to determine the number of transmitting MES within a chosen analysis area. The maximum number of available channels for MES that can be co-channel with the MetSat station is calculated by dividing the channel spacing into the MetSat Station bandwidth. Since channels
