1、 Recommendation ITU-R F.1249-4 (09/2015) Technical and operational requirements that facilitate sharing between point-to-point systems in the fixed service and the inter-satellite service in the band 25.25-27.5 GHz F Series Fixed service ii Rec. ITU-R F.1249-4 Foreword The role of the Radiocommunica
2、tion Sector is to ensure the rational, equitable, efficient and economical use of the radio-frequency spectrum by all radiocommunication services, including satellite services, and carry out studies without limit of frequency range on the basis of which Recommendations are adopted. The regulatory an
3、d policy functions of the Radiocommunication Sector are performed by World and Regional Radiocommunication Conferences and Radiocommunication Assemblies supported by Study Groups. Policy on Intellectual Property Right (IPR) ITU-R policy on IPR is described in the Common Patent Policy for ITU-T/ITU-R
4、/ISO/IEC referenced in Annex 1 of Resolution ITU-R 1. Forms to be used for the submission of patent statements and licensing declarations by patent holders are available from http:/www.itu.int/ITU-R/go/patents/en where the Guidelines for Implementation of the Common Patent Policy for ITU-T/ITU-R/ISO
5、/IEC and the ITU-R patent information database can also be found. Series of ITU-R Recommendations (Also available online at http:/www.itu.int/publ/R-REC/en) Series Title BO Satellite delivery BR Recording for production, archival and play-out; film for television BS Broadcasting service (sound) BT B
6、roadcasting service (television) F Fixed service M Mobile, radiodetermination, amateur and related satellite services P Radiowave propagation RA Radio astronomy RS Remote sensing systems S Fixed-satellite service SA Space applications and meteorology SF Frequency sharing and coordination between fix
7、ed-satellite and fixed service systems SM Spectrum management SNG Satellite news gathering TF Time signals and frequency standards emissions V Vocabulary and related subjects Note: This ITU-R Recommendation was approved in English under the procedure detailed in Resolution ITU-R 1. Electronic Public
8、ation Geneva, 2015 ITU 2015 All rights reserved. No part of this publication may be reproduced, by any means whatsoever, without written permission of ITU. Rec. ITU-R F.1249-4 1 RECOMMENDATION ITU-R F.1249-4* Technical and operational requirements that facilitate sharing between point-to-point syste
9、ms in the fixed service and the inter-satellite service in the band 25.25-27.5 GHz (Question ITU-R 118/7) (1997-2000-2009-2013-2015) Scope This Recommendation provides maximum e.i.r.p. density of transmitting point-to-point fixed service (FS) stations towards the direction of the geostationary-satel
10、lite orbit to enable sharing with the inter-satellite service in the band 25.25-27.5 GHz. The reference e.i.r.p. density in this Recommendation takes into account the need for transmission at the minimum necessary level while taking into account use of automatic transmitter power control (ATPC) at t
11、he FS stations for precipitation events. Keywords Data relay satellites, orbital locations, e.i.r.p., spectral density The ITU Radiocommunication Assembly, considering a) that the frequency band 25.25-27.5 GHz is allocated to the inter-satellite service and the fixed service on a primary basis; b) t
12、hat this frequency band is used for space research and Earth exploration applications for return inter-satellite links to data relay satellites (DRSs) in the geostationary-satellite orbit (GSO); c) that some transmitting stations in the fixed service (FS) may be able to use automatic transmit-power
13、control (ATPC) to reduce their equivalent isotropically radiated power (e.i.r.p.) during clear-weather conditions; d) that aggregate interference from the side lobes of the antennas of a large number of transmitting stations in the FS which do not point towards a DRS has been shown to be tolerable,
14、but that main beam coupling from a single transmitting station in the FS service which does point towards a DRS is considered to represent a potentially severe interference situation (see Annex 1); e) that, whereas exceptionally long FS links require operation at elevated e.i.r.p. densities, these u
15、sually operate near or at zero elevation angles where atmospheric attenuation substantially reduces the potential interference; f) that, under certain circumstances, topography and man-made structures obstruct FS radiation into space, or introduce substantial attenuation into the potential interfere
16、nce path; g) that interference mitigation techniques can be used by both services to minimize the interference from the emissions of FS systems into DRS systems, * This Recommendation was jointly developed by Radiocommunication Study Groups 7 and 5, and future revisions should be undertaken jointly.
17、 2 Rec. ITU-R F.1249-4 recognizing a) that Recommendation ITU-R SA.1155 recommends that the maximum aggregate interference power spectral density levels received in the 25.25-27.5 GHz band by geostationary DRSs in the inter-satellite service should not exceed 178 dB(W/kHz) for more than 0.1% of the
18、time; b) that a limited number of DRS networks are used in the GSO as listed in Recommendation ITU-R SA.1276 (see Note 1); c) that Recommendation ITU-R F.758 provides a large variety of fixed wireless system parameters generalized by representative systems for specific frequency ranges, recommends 1
19、 that the maximum e.i.r.p. within the channel bandwidth of such an FS station should, where practicable, be the minimum necessary for satisfactory operation; 2 that, for the GSO locations specified in Recommendation ITU-R SA.1276 (see Note 1): 2.1 as far as practicable, the e.i.r.p. density of such
20、an FS station in the direction of the above locations should not exceed +24 dBW in any 1 MHz band (see Note 2); 2.2 during conditions when precipitation attenuation is experienced between the FS transmitting and receiving stations, the transmitting station may use ATPC to increase its transmitted po
21、wer, by an amount not exceeding the precipitation attenuation, such that its e.i.r.p. density in the direction of the GSO locations referenced above does not exceed +33 dBW in any 1 MHz band; 2.3 when the atmospheric attenuation towards the GSO locations referenced above, calculated using the proced
22、ures in Annex 1 of Recommendation ITU-R P.676, taking into account the elevation angle towards these orbit locations, the altitude of the FS transmitting antenna and local information of average water vapour content in the driest month and of other meteorological parameters (see Note 3), exceeds 3 d
23、B, this excess may be applied as an increase of the e.i.r.p. density of the FS station; 2.4 when the Fresnel zones on the path from such a transmitting FS station in the direction of the above orbit locations are completely or partially blocked, the e.i.r.p. density in this direction may be increase
24、d by an amount calculated using the methods of Recommendation ITU-R P.526, taking due account of atmospheric refraction on this path (see Recommendation ITU-R F.1333); 2.5 Annex 2 is a method which may be used to calculate separation angles from the specific locations on the GSO; 3 that, for all oth
25、er locations on the GSO: 3.1 the e.i.r.p. density of such an FS station in the direction of the GSO should not exceed +33 dBW in any 1 MHz band; 3.2 Annex 2 to Recommendation ITU-R SF.765 is a method which may be used to calculate separation angles from the GSO (see Note 4); 4 the four following Not
26、es 1, 2, 3 and 4 are part of this Recommendation: NOTE 1 Recommendation ITU-R SA.1276-4 identifies the following geostationary orbital positions: 10.6 E, 16.4 E, 16.8 E, 21.5 E, 47 E, 59 E, 77 E, 80 E, 85 E, 89 E, 90.75 E, 95 E, 113 E, 121 E, 133 E, 160 E, 167 E, 171 E, 176.8 E, 177.5 E, 12 W, 16 W,
27、 32 W, 41 W, 44 W, 46 W, 49 W, 62 W, 139 W, 160 W, 164.2 W, 167.5 W, 170 W, 171 W, 174 W. Rec. ITU-R F.1249-4 3 When Recommendation ITU-R SA.1276 is revised so that new DRS orbital locations are added, the protection of the space stations in these new orbital slots in revision to this Recommendation
28、 applies only to FS stations installed after the enforcement date of the revised Recommendation ITU-R SA.1276. NOTE 2 The interference potential to DRSs from point-to-point fixed wireless systems which exceed the e.i.r.p. density limits outlined in recommends 2.1, may be reduced by avoiding the use
29、of the DRS centre frequencies, where practical. Further study of this mitigation technique is required. NOTE 3 Recommendation ITU-R F.1404 proposes the estimation of atmospheric attenuation using detailed information of local meteorological parameters for the band 25.5-27.5 GHz. Where this is not av
30、ailable a simple procedure, which assumes simplified climate models, is proposed on a provisional basis. This method requires further study. Administrations which have obtained local meteorological parameters for use in estimation of gaseous attenuation are requested to make those data available for
31、 the ITU-R (particularly Radiocommunication Study Groups 3 and 5). NOTE 4 Recommendation ITU-R SF.765 was originally developed to give precise separations up to 2. It is to be noted that the algorithm used in this Recommendation is equally valid to be expanded up to 10 by using B = 10 in 1 of Annex
32、2 to Recommendation ITU-R SF.765. Annex 1 Maximum e.i.r.p. density of point-to-point fixed wireless system transmitters operating in the band 25.25-27.5 GHz shared with the inter-satellite service 1 Introduction This annex summarizes analyses that demonstrate that the protection criteria of Recommen
33、dation ITU-R SA.1155 for DRSs can be satisfied except in the case of main beam-to-main beam coupling by the emissions of point-to-point fixed wireless stations. 2 System models 2.1 Point-to-point FS deployment in the band 25.25-27.5 GHz The following assumptions concerning the technical and operatio
34、nal characteristics of point-to-point FS stations are extrapolated from existing 23 GHz systems: 100 000 transmitters assumed worldwide in the band 25.25-27.5 GHz (the 26 GHz band). Estimated distribution of transmitter e.i.r.p. density levels: more than 70% of all FS links in the 25.25-27.5 GHz ban
35、d are estimated to operate below +24 dB(W/MHz); less than 25% are estimated to operate in the range of +24 dB(W/MHz) to +33 dB(W/MHz); less than 5% are estimated to operate above +33 dB(W/MHz). Single frequency per transmitter. Half transmitters are “go”, half “return”. 4 Rec. ITU-R F.1249-4 Frequen
36、cy channelization in accordance with Recommendation ITU-R F.748 (the recommended channel bandwidths range from 112 MHz to 3.5 MHz and 2.5 MHz, there is a possibility of adding 1.75 MHz and 1.25 MHz bandwidths in the future). Operating channels are distributed across the band. Elevation angles are ty
37、pically in the 0 to 5 range. Path length is typically in the 2 to 5 km range. Large rain fade margins are required in the 26 GHz band to achieve 99.999% availability. Large-scale point-to-point FS providers increasingly use the lowest possible transmitter power options in order to reduce frequency r
38、euse distances. Only a minor number of equipment types are currently available with automatic power control. 2.2 Deployment of DRSs that use space-to-space links in the inter-satellite service The technical and operational characteristics of DRSs to be operated by NASA of the United States of Americ
39、a, the European Space Agency (ESA), the Russian Space Agency, and the Japan Aerospace Exploration Agency of Japan (JAXA) that will use space-to-space links in the 26 GHz band are summarized below: Orbital locations are given in Recommendation ITU-R SA.1276. Typical DRS characteristics: has two high
40、gain single access antennas with a peak gain of 58 dBi; receiving antenna 3 dB beamwidth is less than 0.2; receiving antenna can support one 20/30 GHz band return signal at a time; DRS receiver noise temperature, T = 703 K ( 140.13 dB(W/MHz) noise density); return data rates: 1 kbit/s-300 Mbit/s in
41、a 225 MHz bandwidth; return data rates: 1 kbit/s-800 Mbit/s in a 650 MHz bandwidth; receiving centre frequency is tunable in 25 MHz (or smaller) steps. DRS centre frequencies selected in conformance with Space Network Interoperability Panel (SNIP) recommendations for common DRS return channels will
42、have centre frequencies at: 25.60 GHz, 25.85 GHz, 26.10 GHz, 26.35 GHz, 26.60 GHz, 26.85 GHz, 27.10 GHz or 27.35 GHz. Interference mitigation techniques have neither been studied nor implemented on the current generation of 26 GHz DRS. 3 Interference assessment 3.1 DRS protection criteria Recommenda
43、tion ITU-R SA.1155 Protection criteria related to the operation of data relay satellite systems, recommends that the maximum aggregate interference power spectral density level from all sources to be exceeded for no more than 0.1% of the time be 178 dB(W/kHz) in the 25.25-27.5 GHz band (this is equi
44、valent to 148 dB(W/MHz). This level is based on an I/N = _10 dB and a link margin degradation of 0.4 dB. The recommended maximum reference bandwidth is 1 kHz. The protection criteria translates to a maximum FS interference e.i.r.p. density of 13.5 dB(W/MHz) in the direction of the DRS when there is
45、main beam coupling as shown in Table 1. Rec. ITU-R F.1249-4 5 TABLE 1 Maximum FS e.i.r.p. density in the direction of a DRS for main beam coupling FS e.i.r.p. density (dB(W/MHz) 13.5 Atmospheric loss (dB) 3 Polarization loss (dB) 3 Free space loss (dB) 213.5 DRS peak receive antenna gain (dBi) 58 Ma
46、ximum interference density (dB(W/MHz) 148 3.2 Main beam interference The main beam interference criteria include: the tolerable FS e.i.r.p. density limit that satisfies the DRS protection criteria of Recommendation ITU-R SA.1155; the probability of main beam interference occurrence. The tolerable FS
47、 e.i.r.p. density limit is calculated under the assumptions of co-channel interference into a non-inclined DRS orbit. The assessment of the probability of main beam interference occurrence is based on the operating conditions of the two systems. The case of a FS radio-relay radiating towards a DRS a
48、nd coupling into the main beam of the DRS high gain antenna is considered for a range of e.i.r.p. density levels. The results are given in Table 2. The table shows that an e.i.r.p. spectral density in excess of 13.5 dB(W/MHz), assuming 3 dB loss due to atmospheric absorption and 3 dB polarization lo
49、ss, will result in an interference level greater than the value specified in Recommendation ITU-R SA.1155 when there is direct alignment. TABLE 2 Amount interference criteria is exceeded versus FS e.i.r.p. density radiated towards the DRS FS e.i.r.p. density (dB(W/MHz) 13.5 24 33 DRS spacecraft Rx antenna gain (dBi) 58 58 58 Free space loss (dB) 213.5 213.5 213.5 Atmospheric loss (dB) 3 3 3 Polarization loss (dB) 3 3 3 Interference power, I (dB(W/MHz) 148 137.5 128.5 Maximu
