1、 Rep. ITU-R RS.2095 1 REPORT ITU-R RS.2095 Sharing of the 36-37 GHz band by the fixed and mobile services and the Earth exploration-satellite service (passive) (2007) TABLE OF CONTENTS Page 1 Introduction 2 2 EESS (passive) . 2 2.1 Applications 2 2.2 Passive sensor parameters. 2 2.3 Interference cri
2、teria. 4 3 Fixed and mobile service parameters . 5 3.1 Fixed service (FS). 5 3.2 Mobile service (MS). 6 4 Simulation studies 7 4.1 General simulation methodology 7 4.2 Simulation study number 1. 7 4.3 Simulation study number 2. 9 4.4 Simulation study number 3. 11 4.4.1 P-P FS systems. 11 4.4.2 P-MP
3、FS systems . 15 4.5 Simulation study number 4. 17 4.6 Summary of sharing study results. 20 4.6.1 Sharing between the FS and the EESS (passive) . 20 4.6.2 Sharing between the MS and the EESS (passive) 22 5 Mitigation techniques . 22 5.1 EESS (passive) 22 5.2 FS 24 5.3 MS. 26 6 Summary and conclusions
4、 26 7 Supporting documents 27 2 Rep. ITU-R RS.2095 1 Introduction The purpose of this report is to summarize the result of the studies on sharing the 36-37 GHz band by the fixed and mobile services and the Earth exploration-satellite service (EESS) (passive) 2 EESS (passive) 2.1 Applications The ban
5、d 36-37 GHz is of primary interest to measure rain, snow, ocean ice and water vapour. This band is also called a window. This band is essential for the precise knowledge of the hydrological cycle or global water circulation. For the measurement of surface parameters, some radiometric window channels
6、 must be selected to determine the corresponding expected parameters for the ocean or land surfaces. For ocean surfaces, the main parameters that are measured over the ocean surfaces are: salinity, wind speed, liquid clouds, water vapour and sea surface temperature. Liquid clouds are obtained via me
7、asurements at 36 GHz. Five frequencies (6, 10, 18, 24 and 36 GHz) are necessary for determining the above main parameters. For land surfaces, the problem is more complex due to high temporal and spatial variability of surface characteristics (from snow/ice covered areas to deserts and tropical rain
8、forests). Over this kind of surface, the retrieved parameters are: vegetation biomass, cloud liquid water, integrated water vapour, soil moisture and surface roughness. The use of the 36 GHz allows the retrieval of the contents of the cloud liquid vapour and of the snow covered areas. It has been sh
9、own that this band is the most suitable band for snow detection and has been used for the last 20 years for climatological studies of snow, sea ice, soil moisture, microwave vegetation index and land surface temperature. Measurements at 36 GHz have shown the capability to derive the snow water equiv
10、alent. The use of spaceborne remote sensing techniques offers a way to complement and extend conventional ground based measurements of snow to regional and global scales. There is a continuing need to determine the snow water equivalent and its variability over large areas for climatological and hyd
11、rological applications. In addition to the snow water equivalent, it is also possible to derive from spaceborne microwave remote sensing measurements, the snow depth based on the physics of the microwave radiation. The 36-37 GHz band measurements also provide auxiliary parameters for other remote se
12、nsing instruments. Spaceborne radar altimeters are currently operated on a global basis above ocean and land surfaces, with important applications in oceanography and climatology. In order to remove refraction effects due to the atmosphere, the utilization of highly accurate altimetric data require
13、that they are complemented with a set of auxiliary passive measurements around 18.7, 23.8 and 36.5 GHz. In that case, the goal of the 36 GHz band measurements is to compute the tropospheric delay in order to enhance the accuracy of the data retrieved through the altimeters. It is to be noted that al
14、l the above usages are fully operational. 2.2 Passive sensor parameters Table 1 summarizes the parameters of conical scanning passive sensors that are or will be operating in the 36-37 GHz band as illustrated in Fig. 1. Rep. ITU-R RS.2095 3 TABLE 1 Passive sensor parameters Type of sensor MADRAS AMS
15、R-E CMIS Channel bandwidth (GHz) 1 1 1 Pixel size across track (diameter of the pixel) (km) 38 7.8 12 Incidence angle i at footprint centre (degrees) 52.3 55 55.7 Offset angle to the nadir or half cone angle (degrees) 44.5 47.5 47 Polarization H H,V H,V Altitude of the satellite (km) 817 705 833 Max
16、imum antenna gain (dBi) 45 53 55 Reflector diameter (m) 0.65 1.6 2.2 Half power antenna beamwidth 3dB(degrees) 1.8 0.4 0.52 Useful swath (km) 1 607 1 450 1 782 Antenna pattern Fig. 2 Fig. 3 N/A FIGURE 1 Geometry of conical scan passive microwave radiometers 4 Rep. ITU-R RS.2095 The antennas of passi
17、ve sensors are modelled according to the following figures. FIGURE 2 MADRAS antenna gain pattern at 36 GHz FIGURE 3 AMSR-E antenna gain pattern at 36 GHz 2.3 Interference criteria Recommendation ITU-R RS.1029 Interference criteria for satellite passive remote sensing recommends permissible interfere
18、nce levels and reference bandwidths for use in any interference assessment or sharing studies. The permissible interference levels for the 36-37 GHz band are 156 dBW in a reference bandwidth of 100 MHz for current passive sensors, and 166 dBW in a reference bandwidth of 100 MHz for future passive se
19、nsors that are more sensitive than the currently operational passive sensors. The first number is indicated for sharing conditions circa 2003; while the second number is for scientific requirements that are technically achievable by sensors in the next 5-10 years. Recommendation ITU-R RS.1029 also s
20、pecifies that these interference levels should not be exceeded for more than 0.1% of sensor viewing area, described as a measurement area of a square on the Earth of 10 000 000 km2unless otherwise justified. Rep. ITU-R RS.2095 5 3 Fixed and mobile service parameters 3.1 Fixed service (FS) FS systems
21、 in this band can generally be characterized as either point-to-point (P-P) or point-to-multipoint (P-MP) systems. Table 2 summarizes the parameters of P-P system that could operate in the 36-37 GHz that were considered in these studies. TABLE 2 P-P FS station parameters Parameter FS-1 FS-2 Modulati
22、on type O QPSK Distance between stations (one hop length) (km) Around 2 From 0.5 to 20 Point-to-point Channel capacity (Mbit/s) 2.048; 8.448; 34.368 Receiver sensitivity (BER up to 106) (dBW) Up to 117 Transmitter power (dBW) 18.24 dBW/30 MHz (= 15 mW/30 MHz) 13 to 7 Antenna gain (dBi) 37 39-42 Ante
23、nna diameter (m) 0.4-0.5 Antenna type Parabolic Antenna pattern Rec. ITU-R F.1245 Max. feeder loss (dB) 0.5 Frequency grid Rec. ITU-R F.749 Table 3 summarizes the parameters of one possible type of terrestrial P-MP station that could operate in the 36-37 GHz. TABLE 3 P-MP FS station parameters Param
24、eter Central (hub) station Customer terminal station Modulation QPSK Access method Time division multiplex (TDM) Bandwidth/carrier (MHz) 28 28 Antenna type Sectoral antenna Dish Antenna gain (dBi) 17 39 Antenna beamwidth (degrees) 45 1.4 Number of active carriers/sector 4 4 Number of sectors 8 6 Rep
25、. ITU-R RS.2095 TABLE 3 (end) Parameter Central (hub) station Customer terminal station Path length (km) 0.1 6 Maximum transmit power per carrier (dBW) 5 10 Receiving system line loss (dB) 0 0 3.2 Mobile service (MS) Technical characteristics of systems in the MS operating in the band 36-37 GHz are
26、shown in Table 4. As for the antenna pattern, Recommendation ITU-R F.1245 Mathematical model of average radiation patterns for line-of-sight point-to-point radio-relay system antennas for use in certain coordination studies and interference assessment in the frequency range from 1 to about 70 GHz is
27、 used in the simulation. MS-1 and MS-2 systems are used mainly for video transmission in nomadic applications. Their corresponding activity factor is 3%. In European countries, the band 36-37 GHz is allocated to the MS and the FS for the usage of government applications. Due to the specific operatio
28、n, the MS-3 system which is used for government point-to-point links can be considered as MS systems due to their portable usage. It is noted that the characteristics of such MS stations are very similar to the FS station characteristics assumed in the dynamic simulations, so that the conclusions of
29、 the FS studies are generally assumed to be applicable to the MS. TABLE 4 Mobile service station parameters Parameter MS-1 MS-2 MS-3 Antenna input power 7 dBW/17 MHz (= 0.2W/17 MHz) 3 dBW/17 MHz (= 0.5W/17 MHz) 10 dBW (max) 15 dBW (typical) Antenna gain (dBi) 37 37 44 (typical) Antenna diameter (m)
30、0.3 0.3 0.3 Antenna type Parabolic/Cassegrain Parabolic Parabolic Feeder loss (dB) 0 0 0 Polarization H/V H H/V 3 dB beam width (degrees) 2 2 1 NOTE 1 Elevation angles are not specified because of its nomadic usage. This means that the transmitting antenna has a possibility to point any elevation an
31、d azimuth angles. However, the antenna is fixed during its operation. NOTE 2 MS-1: More than 30 transmitting stations are in operation and it is foreseen that the number of the stations will not increase rapidly in some administrations. MS-2: More than one transmitting station is in operation and it
32、 is foreseen that the number of the stations will not increase rapidly in some administrations. Rep. ITU-R RS.2095 7 4 Simulation studies 4.1 General simulation methodology These sharing studies employ dynamic model simulations with the results required by Recommendation ITU-R RS.1029 concerning the
33、 percentage of the area over a 10 million km2measurement area that exceed the permissible interference power level. These dynamic model simulations develop cumulative distribution functions (CDFs) of received interference levels on the basis of such measurement areas so that such interference statis
34、tics can be directly compared with the specified interference criteria. 4.2 Simulation study number 1 This simulation assumes a deployment of 200 P-P FS stations evenly spread over an area defined by 40 N latitude, 0 longitude, 60 N latitude, and 20 E longitude. The transmitter power is 10 dBW and t
35、he antenna gain is 41 dBi, corresponding to an e.i.r.p. of 31 dBW. The propagation model includes atmospheric attenuations and the time increment for simulation is 2 s. The simulation results are given in Fig. 4 and Table 5 for the MADRAS passive sensor, in Fig. 5 and Table 6 for AMSR-E, and in Fig.
36、 6 and Table 7 for CMIS. FIGURE 4 Dynamic simulation for the MADRAS passive sensor TABLE 5 Result of dynamic simulation corresponding to Fig. 4 Cumulative percentage (%) 1 0.2 0.1 0.02 Corresponding received power at the input of the radiometer in dBW for MADRAS for a 100 MHz bandwidth 177 167 166 1
37、63 8 Rep. ITU-R RS.2095 FIGURE 5 Dynamic simulation for the AMSR-E passive sensor TABLE 6 Result of dynamic simulation corresponding to Fig. 5 Cumulative percentage (%) 10 1 0.1 0.05 Corresponding received power at the input of the radiometer in dBW for AMSR-E 188 175 172 156 Rep. ITU-R RS.2095 9 FI
38、GURE 6 Dynamic simulation for the CMIS passive sensor: 200 P-P stations in operation TABLE 7 Result of dynamic simulation corresponding to Fig. 6 Cumulative percentage (%) 10 2 1 0.1 0.02 Corresponding received power at the input of the radiometer in dBW for CMIS 180 166 165 152 145 4.3 Simulation s
39、tudy number 2 This simulation is designed to develop a relationship between FS station deployment density and the EESS (passive) interference level. The simulation was conducted for the AMSR-E passive sensor, and each FS station was assumed to have a 11 dBW transmitter power and to employ a 40.5 dBi
40、 antenna whose side-lobe conform to the reference antenna pattern given in Recommendation ITU-R F.1245 for a 3 dB beamwidth of 1.5. In this simulation model, a large range of FS station deployment densities was achieved by assuming that between 1 and 20 two-way FS links were randomly distributed aro
41、und 74 cities in and around the 107km2passive sensor measurement area illustrated in Fig. 7. Of the 74 cities in the simulation area in central Asia illustrated in Fig. 10, 66 were located within the 107km2passive sensor measurement area itself. The FS station density, NFS, within this area is calcu
42、lated as: NFS= 2 (stations/link) x FS (links/city) x 66 (cities) where FS is the number of FS links/city assumed for the particular interference CDF. 10 Rep. ITU-R RS.2095 FIGURE 7 Central Asia measurement area The resulting interference CDF for this simulation include calculations only for time ste
43、ps for which the passive sensor beam intersected the Earths surface within the measurement area and are displayed in Fig. 8. FIGURE 8 Interference CDFs from dynamic simulations Rep. ITU-R RS.2095 11 4.4 Simulation study number 3 This study addressed both P-P and P-MP FS systems. These simulations in
44、cluded in this study were conducted to develop interference CDF over the three different passive sensor 10 000 000 km2measurement areas illustrated in Fig. 9, each with different FS deployment densities, for comparison with Recommendations ITU-R RS.1029, which specifies permissible interference crit
45、eria for passive sensors in this band in terms of percentage of a 10 million km2measurement area over which the specified interference level is exceeded. The FS station density for each of these areas is based on the assumption of a single frequency use of the channel plan described in Annex 2 to Re
46、commendation ITU-R F.749 Radio-frequency channel arrangements for radio-relay systems in the 38 GHz band within each city. Interference into the passive stations is evaluated under free space propagation conditions, plus an additional loss of 0.32 dB for atmospheric (gaseous) absorption from Recomme
47、ndation ITU-R P.676 Attenuation by atmospheric gases for the Earth-to-space path. FIGURE 9 FS deployment areas City model 4.4.1 P-P FS systems Two types of FS deployment models were used in these simulation studies. It is commonly assumed that FS systems are predominantly deployed in urban and sub-u
48、rban areas, with few if any systems in rural areas. Therefore the first scenario is the “City Model” which distributes FS stations around urban cities within a given simulation area. However, some administrations indicate FS applications 12 Rep. ITU-R RS.2095 in the 36-37 GHz that may be distributed
49、 over wider areas, including rural area, including intermittent operations. For this reason a second scenario is identified as the “Random Model” which focuses on when the FS systems that are randomly distributed over the land area within the specified measurement area with a uniform probability distribution. The P-P FS deployment densities are presented in Table 8 for the cases assumed in these simulations, based on the channel bandwidth. TABLE 8 P-P FS deployment densities Channel bandwidth (MHz) 112 56 28 14 7 FS stations/City 4 8 15
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