1、 Rec. ITU-R SF.1650-1 1 RECOMMENDATION ITU-R SF.1650-1 The minimum distance from the baseline beyond which in-motion earth stations located on board vessels would not cause unacceptable interference to the terrestrial service in the bands 5 925-6 425 MHz and 14-14.5 GHz*,*(Questions ITU-R 226/9 and
2、ITU-R 251/4) (2003-2005) Scope This Recommendation provides the offshore distance beyond which earth stations on board vessels (ESVs) will not interfere with fixed service systems. The Annex provides the assumptions and methodology used in determining these distances in the frequency bands 5 925-6 4
3、25 MHz and 14-14.5 GHz. The ITU Radiocommunication Assembly, considering a) that the technology exists which permits the use of FSS networks by earth stations on board vessels (ESVs) in the bands 5 925-6 425 MHz and 14-14.5 GHz (Earth-to-space); b) that ESVs have the potential to cause unacceptable
4、interference to FS systems in these bands; c) that ESV operations require considerably less than the full bandwidth in this FSS allocation and only a portion of the visible GSO arc; d) that in order to ensure the protection and future growth of the FS, the ESV must operate with certain operational c
5、onstraints; e) that a minimum distance from the low-water mark as officially recognized by the coastal State could be determined beyond which the ESV will not cause unacceptable interference to the FS in these bands; f) that the minimum distance in considering e) may be based on administrative and t
6、echnical considerations, noting a) that some administrations have been operating ESVs for several years under No. 4.4 of the Radio Regulations (RR), *With respect to the impact to other terrestrial services other than the fixed service (FS), this will be the subject of further study. *The Administra
7、tions of Saudi Arabia, Djibouti, Egypt, United Arab Emirates, Jordan, Kuwait, Morocco, Mauritania, Syrian Arab Republic, Tunisia and Yemen objected to the approval of this Recommendation for the reasons that can be found in the Radiocommunication Assembly (Geneva, 2003) (RA-03) Report to the WRC-03.
8、 The Administrations of Germany, Australia, Canada and Israel reserve their opinion on this Recommendation for the reasons that can be found in the RA-03 Report to the WRC-03. The Administrations of Gabon and Senegal reserve their opinion on this Recommendation. 2 Rec. ITU-R SF.1650-1 recommends 1 t
9、hat, in the band 5 925-6 425 MHz, the minimum distance from the low-water mark as officially recognized by the coastal State, beyond which in-motion ESVs would not cause unacceptable interference to the terrestrial services is 300 km for an antenna of 2.4 m diameter (based on the parameters of Table
10、 1); 2 that, in the band 14-14.5 GHz, the minimum distance from the low-water mark as officially recognized by the coastal State, beyond which in-motion ESVs would not cause unacceptable interference to the terrestrial services is 125 km for an antenna of 1.2 m diameter in bands shared with the terr
11、estrial services (based on the parameters of Table 2). NOTE 1 The purpose of this Recommendation is to protect terrestrial services to which the frequency bands are allocated. As for the protection of the space services in the same frequency bands the matter is dealt with in Recommendation ITU-R S.1
12、5871. Annex 1 Method to use in development of a minimum distance for the 5 925-6 425 MHz and 14-14.5 GHz bands 1 Method to determine the distance The maximum permissible interference power is )(log1010 FSRFSRthmaxBTkNII += dBW (1) where: thNI: interference to thermal noise power ratio defined in int
13、erference criterion (dB) k: Boltzmans constant (W/(K Hz) TFSR: system noise temperature of the fixed service receiver (FSR) (K) BFSR: bandwidth of FSR (Hz). Once the short-term interference criterion has been defined, the minimum permissible transmission loss is given by subtracting the FSRs permiss
14、ible interference power level from the sum of the ESVs e.i.r.p. in the direction of the FSR and the FSRs average antenna gain in its 10 dB beamwidth. The minimum permissible transmission loss is therefore given by: FIGGPpLmaxAVErtmaxtsminb)(,+= (2) 1The characteristics of the ESVs need to be within
15、the envelope of those initially published in the BR IFIC relating to the corresponding FSS network. Otherwise, the earth stations need to be coordinated in accordance with the current provisions of the RR and the relevant Rules of Procedure (i.e. 2 of the Rules of Procedure relating to RR No. 11.32)
16、. Rec. ITU-R SF.1650-1 3 where: Lb, min: minimum required basic transmission loss (dB) Pt, max: maximum transmit power at the ESV antenna input flange (dBW) Gt: ESV antenna gain in the direction of the FSR (dBi) Gr, AVE: average gain of the FSR antenna within its 10 dB beamwidth (dBi) Imax: maximum
17、permissible interference power (dBW) F: loss in the feed from the FSR antenna to the low-noise amplifier (dB). Because the ESV is not always present, it is not appropriate to use the short-term interference objective time percentage, ps, directly as the propagation model input parameter, p, which is
18、 the time percentage for which the required minimum transmission loss is not exceeded (e.g. in Recommendations ITU-R P.452 or ITU-R P.620). The appropriate p depends on how much time the ESV spends within the 10 dB beamwidth of the FSR. But as is clear in Fig. 1, this amount of time depends on the d
19、istance from the ESV to the FSR. Since p depends on this distance and vice versa, an iterative method for determining the minimum distance dxxx, that satisfies the short-term interference criteria is unavoidable. Figure 2 presents a flow chart that details the iterative procedure. The procedure can
20、be initiated under the assumption that the ESV is always present, yielding dxxx(0). The next iteration determines how much time the ESV would spend in the 10 dB beamwidth of the FSR at the distance dxxx(0) and then calculates dxxx(1) based on the resulting value of p. The procedure continues until t
21、he difference between dxxxon successive iterations is less than a threshold, . It is recommended that = 3 km. 4 Rec. ITU-R SF.1650-1 n: stage of the iteration, n = 0, 1, 2, . Imax: maximum permissible interference power (dBW) Ps: time percentage (annual) for which Imaxbe exceeded (%) PESV: time perc
22、entage (annual) for which ESVs are present (%) ESV: ships speed (km/h) p: time percentage (annual) for which minimum required transmission loss is not exceeded (%) : 3 km is recommended (distances 10 Lower elevation angles may be used provided that the e.i.r.p. towards the horizon is consistent with
23、 the 10 elevation angle operational limitation Horizon gain angle, h(degrees) 0 Equation (24) of Recommendation ITU-R SM.1448 = 0 in worst case Maximum transmit power at input to antenna, Pt, max(dBW) 16.7 Minimum antenna diameter, Dmin (m) 2.4 Antenna gain in direction of FSR, Gt= GESV() (dBi) +4 t
24、o 10 Equation (33) of Recommendation ITU-R SM.1448 Maximum occupied bandwidth, BESV(MHz) 2.346 Data rate, RESV(Mbit/s) 1.544 Ships speed, ESV(km/h) 18.3 Typical minimum value when out to sea (10 knots) Frequency of passage, fESV(passes/year) which fall into FSR receiver channel bandwidth Variable Se
25、e 3.5 FSR parameters Frequency of operation, f (MHz) 6 000 Equal to ESV value Antenna height above ground, hrg(m) 70 6 Rec. ITU-R SF.1650-1 TABLE 1 (continued) FSR parameters (continued) Parameter Value Comment Ground height above mean sea level, hg(m) 50 Antenna height above mean sea level, hrs= hg
26、+ hrg(m) 120 Calculation using values above Maximum boresight antenna gain, Gr= GFSR(0) (dBi) 45 Recommendation ITU-R F.758 10 dB beamwidth, FSR, 10 dB(degrees) 1.72 Recommendation ITU-R F.699 Average antenna gain in 10 dB beamwidth, Gr, AVE(dBi) 42.5 Calculated Feeder loss, F (dB) 3 Receiver bandwi
27、dth, BFSR(MHz) 11.2 Noise temperature, TFSR(K) 750 Recommendation ITU-R SM.1448 Data rate, RFSR(Mbit/s) 34 Reference path length (km) 25 Short-term interference objective Interference criteria, I/Nth(dB) I/N = 23 dB, not to be exceeded for more than 1.2 105% of the time for the severely errored seco
28、nd (SES) level. I/N = 19 dB, not to be exceeded for more than 4.5 104% of the time for the errored second (ES) level These figures are based on a net fade margin of 24 dB referenced to the 1 103BER level. Note that the interference criterion associated with the ES level is the more stringent criteri
29、on and hence this is used to determine the required distance Permissible interference power level, Imax(dBW) 110.4 = 10 log(k TFSRBFSR) + I/NthTime percentage for which Pinterference,Smay be exceeded, ps(%) 4.5 104% Tracking accuracy of ESV antenna 0.2 peak Rec. ITU-R SF.1650-1 7 TABLE 1 (end) Calcu
30、lation (dB) of minimum permissible transmission losses Parameter Value Comment Loss, Lb, min(ps) (dB) Calculated See equation (2) Range of ESV from FSR, dxxx(km) Calculated Distance travelled by ESV through 10 dB beamwidth, dESV in beam(km) Calculated = 2dxxxtan(FSR, 10 dB/2) Time spent by ESV in 10
31、 dB beamwidth, tESV in beam(h) Calculated = dESV in beam/ESV ESV interference percentage, pESV(%) Calculated = (fESVtESV in beam/8 760) 100% Time percentage for which Lb, min(ps) is not exceeded, p (%) Calculated = (ps/pESV) 100% 2.2 Parameter values for the 14 GHz band TABLE 2 Parameters used in ca
32、lculating the minimum distance ESV parameters Parameter Value Comment Frequency of operation, f (MHz) 14 250 Antenna height above sea level, hts(m) 40 Elevation angle to satellite, (degrees) 10 Lower elevation angles may be used provided that the e.i.r.p. towards the horizon is consistent with the 1
33、0 elevation angle operational limitation Horizon gain angle, h(degrees) 0 Maximum transmit power at input to antenna, Pt, max(dBW) 12.2 Minimum antenna diameter, Dmin (m) 1.2 Antenna gain in direction of FSR, Gt= GESV() (dBi) +4 to 10 Maximum occupied bandwidth, BESV(MHz) 2.346 Data rate, RESV(Mbit/
34、s) 1.544 Ships speed, ESV(km/h) 18.3 Typical minimum value when out to sea (10 knots) 8 Rec. ITU-R SF.1650-1 TABLE 2 (continued) ESV parameters (continued) Parameter Value Comment Frequency of passage, fESV(passes/year) which fall into FSR receiving channel bandwidth Variable See 3.6 FSR parameters
35、Frequency of operation, f (MHz) 14 250 Equal to ESV value Antenna height above ground, hrg(m) 30 Ground height above mean sea level, hg(m) 50 Antenna height above mean sea level, hrs= hg+ hrg(m) 80 Sum of values above Maximum boresight antenna gain, Gr= GFSR(0) (dBi) 43 For 1.2 m antenna 10 dB beamw
36、idth, FSR, 10 dB(degrees) 2.2 Calculated from Recommendation ITU-R F.1245 Average antenna gain in 10 dB beamwidth, Gr, AVE(dBi) 40.5 Calculated Feeder loss, F (dB) 3 Data rate (Mbit/s) 34 Receiver bandwidth, BFSR(MHz) 14 For 34 Mbit/s link Net fade margin referenced to the 1 103BER level (dB) 24 I/N
37、 applicable to ES criterion (I/Nth) 19 Noise figure, NF (dB) 4.5 Tracking accuracy of ESV antenna 0.2 peak Short-term interference objective Parameter Value Comment Permissible interference power level, Pinterference, S(dBW) 109 = 10 log(k T BFSR) + NF + I/Nth Time percentage for which Imaxmay be ex
38、ceeded, ps(%) 2.7 104Calculation (dB) of minimum permissible transmission losses Loss, Lb, min(ps) (dB) Calculated See equation (2) Rec. ITU-R SF.1650-1 9 TABLE 2 (end) Calculation of applicable time percentage for which minimum propagation loss is not exceeded considering that ESVs are not always p
39、resent Sample range of ESV from FSR, dxxx(km) Calculated Distance travelled by ESV through 10 dB beamwidth, dESV in beam(km) Calculated = 2dxxx tan(FSR, 10 dB/2) Time spent by ESV in 10 dB beamwidth, tESV in beam(h) Calculated = dESV in beam /ESVESV interference percentage, pESV(%) Calculated = (fES
40、V tESV in beam/ 8 760) 100% Time percentage for which Lb, min(ps) is not exceeded, p (%) Calculated = (ps/ pESV) 100% 3 Discussion of assumptions and parameter values 3.1 Maximum ESV transmit power The value of Pt, maxis the power at the antenna input and not the maximum output power from the ESV tr
41、ansmitter high-power amplifier (HPA). The value of Pt, maxmust take into account the sum of losses incurred in all waveguides, cables and rotary joints that may be in the signal path between the HPA output and the antenna input flange. Pt, maxis the assumed power level at the input of the antenna of
42、 an ESV transmitting at the maximum bit rate and hence represents the worst-case value of any ESV. For the 6 GHz band, Pt, max = 16.7 dBW and for the 14 GHz band, Pt, max= 12.2 dBW. However, the value of transmitter power strongly depends on the required bit rate and on other system characteristics.
43、 For 6 GHz ESVs the transmitter power may be about 0 dBW (16.7 dB less than Pt, max) for low bit-rate carriers and for 14 GHz ESVs the transmitter power may be as low as about 13 dBW (25.2 dB less than Pt, max) for low bit-rate carriers. 3.2 ESV gain in the direction of the FSR Under the worst-case
44、assumption that the azimuth angles from the ESV to the FSR, and from the ESV to the ESVs desired satellite are equal, Gtis defined as follows: )(ESVESVtGG = dBi (3) where: GESV (): ESV antenna gain at off-boresight angle , at the transmit frequency (dBi) ESV : elevation angle of the ESV antenna with
45、 respect to the horizontal (degrees). In any other case, Gtwould be given by GESV)( where )( is the angle between the ESV antenna boresight and the horizon in the azimuth direction of the FSR ( )( ESV). GESV() is the boresight (maximum) gain of the ESV antenna and is measured with respect to the ant
46、enna boresight. 10 Rec. ITU-R SF.1650-1 Calculation results are presented for example discrimination angles of 10, 20 and 36. The results for 36 are also applicable for all discrimination angles exceeding 36. The probability of occurrence of each value depends on the relative azimuth of the ESV with
47、 regards to the FS direction, the minimum ESV elevation to consider, and finally the latitude under which the ESV operates, which controls the maximum ESV elevation. It is therefore possible to calculate the antenna discrimination for all the geometrical cases taking into account the ESV azimuth rel
48、ative to the FSR (from 0 to 360) and its elevation (from the minimum elevation to the maximum elevation depending, for the latter, on the considered latitude). On this basis, the distributions of such antenna discrimination for certain latitude are given in Fig. 3 for an assumed minimum elevation of
49、 10. As confirmed in Table 3, Fig. 3 shows that the occurrence of antenna discrimination lower than 36 is small, for lower latitudes in particular. A discrimination angle less than 36 occurs in 17.5% of the cases (at 60 latitude) to 4.6% of the cases (at 0 latitude). In addition, a discrimination lower than 20 only represents 2.3% at 45 latitude. It can be noted from Fig. 3 that (for a 10 minimum elevation), 10 discrimination on
