1、 Rec. ITU-R F.1501 1 RECOMMENDATION ITU-R F.1501 COORDINATION DISTANCE FOR SYSTEMS IN THE FIXED SERVICE (FS) INVOLVING HIGH-ALTITUDE PLATFORM STATIONS (HAPSs) SHARING THE FREQUENCY BANDS 47.2-47.5 GHz AND 47.9-48.2 GHz WITH OTHER SYSTEMS IN THE FIXED SERVICE (Question ITU-R 212/9) (2000) Rec. ITU-R
2、F.1501 The ITU Radiocommunication Assembly, considering a) that WRC-97 designated the bands 47.2-47.5 GHz and 47.9-48.2 GHz for use by HAPSs in the FS; b) that, subject to the provisions of Resolution 122 (Rev.WRC-2000), these bands are also allocated for use by the fixed, fixed-satellite and mobile
3、 services; c) that frequency sharing for fixed-service systems using HAPSs and other systems in the FS is being considered in ITU-R; d) that there may be a requirement to establish criteria for determining coordination distances within which detailed sharing arrangements would need to be considered,
4、 or that there may be a requirement to specify predetermined coordination distances, recommends 1 that Annex 1 should be used for the determination of coordination distance or as a basis for establishing a predetermined coordination distance between stations operating in a high-altitude platform net
5、work (HAPN) and other stations in the FS. ANNEX 1 Coordination distance for systems involving the use of HAPSs 1 Geometrical coordination distance For an initial assessment, it may be appropriate to use a coordination distance based on the above-the-horizon visibility (including atmospheric refracti
6、on) between a HAPS and other stations in the conventional FS or in HAPN. The following predetermined coordination distance (measured from the sub-HAPS point) should be adopted between a HAPS and ground terminals of other systems in the conventional FS or in different HAPNs: km)274.06.141(150 hh+ (1)
7、 where h is the HAPS altitude (km) above sea level in the 20-50 km range. The following predetermined coordination distance (measured from the sub-HAPS point) should be adopted between HAPSs in different systems: km)274.06.141()274.06.141(2211hhhh + (2) where h1and h2are the HAPS altitude (km) above
8、 sea level of two systems, both in the 20-50 km range. 2 Rec. ITU-R F.1501 2 Coordination distance using typical system parameters and representative propagation conditions for the bands of 47.2-47.5 GHz and 47.9-48.2 GHz 2.1 Minimum propagation attenuation due to atmospheric gases 2.1.1 Attenuation
9、 between a HAPS and ground terminals In the path between a HAPS and ground terminals of other systems in the conventional FS or in different HAPN, atmospheric gases including water vapour cause attenuation, which depends on the distribution along the path of meteorological parameters such as tempera
10、ture, pressure and humidity, and thus varies with the geographic location of the site, the month of the year, the height of a ground terminal above sea level, the elevation angle of the slant path and the operating frequency. According to Recommendation ITU-R SF.1395, the following numerical formula
11、e can be used for estimating minimum slant path attenuation in the 47 GHz band where: AL (h, ), AM(h, ) and AH(h, ): total atmospheric absorption loss (dB) for the low-latitude (within 22.5 of the Equator), mid-latitude (greater than 22.5, but less than 45 from the Equator) and high-latitude (45 or
12、more from the Equator) areas, respectively; h and : ground terminal antenna altitude above sea level (km) and elevation angle (degrees), respectively. The approximation was carried out for 0 h 3 km and 0 90. The actual elevation angle may be determined from the elevation angle developed under free s
13、pace propagation conditions using the method in Recommen-dation ITU-R F.1333. For actual elevation angles below 0, the attenuation for 0 should be used. Frequency band 47.2-47.5 GHz In this frequency band, the attenuation is larger at higher frequencies and, therefore, the following formulae give th
14、e attenuation at 47.2 GHz. )02637.008130.0()2479.02624.0(1040.8020.0010990.036017364.043.52) ,(24532+/1=hhhAL(3a) )03239.005539.0()1970.02527.0(1087870.0.0010810.035687004.000.47) ,(24532+/1=hhhAM(3b) )03221.004858.0()1819.02472.0(1008780.0.0011050.036376872.070.46) ,(24532+/1=hhhAH(3c) Frequency ba
15、nd 47.9-48.2 GHz In this frequency band, the attenuation is larger at higher frequencies and, therefore, the following formulae give the attenuation at 47.9 GHz. )02443.007645.0()2382.02576.0(1082670.0.0010740.035347262.009.57) ,(24532+/1=hhhAL(4a) )03176.005420.0()1940.02495.0(1084070.0.0010760.035
16、556962.006.53) ,(24532+/1=hhhAM(4b) )03191.004791.0()1812.02476.0(1007380.0.0011030.036326864.021.53) ,(24532+/1=hhhAH(4c) Rec. ITU-R F.1501 3 2.1.2 Attenuation between two HAPSs If two HAPSs use two frequency bands for opposite directions of transmission, there is a possibility of unacceptable inte
17、rference between them. If the distance between sub-HAPS points is sufficiently large, the path may be subject to attenuation due to atmospheric gases mainly in the lower atmosphere. The method of estimating the minimum value of this attenuation is described below. First, calculate the average altitu
18、de, h0(km), of the altitudes h1 and h2 of two HAPS platforms as follows: h0= (h1+ h2)/2 (5) It is assumed that h1 and h2 may be different, but the difference is not significant (see Note 2). Then from Table 1 for 20 h0 30 km, calculate the minimum altitude of the path, h(km), between two HAPSs. For
19、those values of h0 and the distance which are not given in Table 1, the minimum altitude of the path can be estimated by means of an appropriate interpolation. Table 1 was produced for the atmospheric refractivity model of maximum refraction as defined in Recommenda-tion ITU-R SF.765. TABLE 1 Minimu
20、m altitude of the path between two HAPSs Sub-HAPS distance (km) Minimum altitude of the path, h (km) For average altitude of two HAPSs, h020 km 22 km 24 km 26 km 28 km 30 km 350 400 450 500 550 600 650 700 750 800 850 900 950 1 000 1 050 1 100 1 150 1 200 1 250 1 300 1 350 1 400 1 450 17.63 16.91 16
21、.10 15.20 14.22 13.16 12.03 10.84 9.61 8.36 7.11 5.89 4.73 3.64 2.66 1.78 1.00 0.32 17.16 16.16 15.08 13.92 12.69 11.41 10.09 8.75 7.42 6.13 4.91 3.77 2.75 1.84 1.04 0.35 17.03 15.85 14.59 13.26 11.89 10.47 9.05 7.64 6.29 5.01 3.84 2.79 1.89 1.05 0.35 17.79 16.51 15.16 13.74 12.27 10.77 9.26 7.79 6.
22、37 5.05 3.85 2.78 1.84 1.02 0.32 17.08 15.63 14.12 12.56 10.97 9.39 7.85 6.38 5.03 3.80 2.72 1.77 0.96 0.26 17.55 16.01 14.40 12.75 11.08 9.43 7.83 6.33 4.95 3.71 2.62 1.68 0.87 0.18 4 Rec. ITU-R F.1501 When h 17 km, the attenuation is negligibly small. If 0 h 17 km, the minimum propagation attenuat
23、ion can be estimated by the following numerical formulae, where: AL(h), AM(h), AH(h): total atmospheric absorption loss (dB) for the low-latitude, mid-latitude and high-latitude areas, respectively. Frequency band 47.2-47.5 GHz )000031666.000018436.00.00475980.09279559602.0(63.041)(5432hhhhhhAL+1/=(
24、6a) )00014071.00024068.00.0180330.01072981382.0(94.93)(5432hhhhhhAM+1/=(6b) )00012031.00013613.00.00960810.02390027156.0(39.93)(5432hhhhhhAH+1/=(6c) Frequency band 47.9-48.2 GHz )000030414.000016894.00.00419780.08584055202.0(28.511)(5432hhhhhhAL+1/=(7a) )00013852.00023697.00.0178340.009722329582.0(0
25、7.106)(5432hhhhhhAM+1/=(7b) )00011928.00013468.00.00958580.02302027253.0(44.106)(5432hhhhhhAH+1/=(7c) NOTE 1 When 0 h 3 km, the values of equations (6a)-(7c) are almost twice the values of equations (3a)-(4c) for the same altitude and = 0. NOTE 2 For the same average altitude h0, when h1and h2are un
26、equal, the minimum altitude of the path becomes slightly lower, resulting in slightly larger atmospheric absorption loss. Table 2 shows the minimum altitude (km) of the path for the case of h0= 25 km. The effects of unequal HAPS altitudes are small. TABLE 2 Minimum altitude of the path for the case
27、of h0= 25 km 2.2 Coordination distance using typical system parameters This matter requires further study. Sub-HAPS distance (km) Minimum altitude of the path (km) For h1 and h225/25 km 24/26 km 23/27 km 22/28 km 21/29 km 20/30 km 700 900 1 100 1 300 15.55 9.90 4.43 0.68 15.52 9.88 4.42 0.67 15.45 9.84 4.40 0.66 15.32 9.77 4.36 0.64 15.14 9.66 4.31 0.62 14.90 9.53 4.24 0.58
