1、Rec. ITU-R F.1338 1RECOMMENDATION ITU-R F.1338*, *, *THRESHOLD LEVELS TO DETERMINE THE NEED TO COORDINATEBETWEEN PARTICULAR SYSTEMS IN THE BROADCASTING-SATELLITESERVICE (SOUND) IN THE GEOSTATIONARY-SATELLITE ORBIT FORSPACE-TO-EARTH TRANSMISSIONS AND THE FIXED SERVICEIN THE BAND 1 452-1 492 MHz(Quest
2、ion ITU-R 111/9)(1997)Rec. ITU-R F.1338The ITU Radiocommunication Assembly,consideringa) that the World Administrative Radio Conference for Dealing with Frequency Allocation in Certain Parts of theSpectrum (Malaga-Torremolinos, 1992) (WARC-92) allocated the band 1 452 - 1 492 MHz on a primary basis
3、to thebroadcasting-satellite service (sound) (BSS (sound) subject to the provisions of Radio Regulations (RR) Nos. S5.342,S5.343, S5.344 and S5.347, and to Resolution No. 528 (WARC-92);b) that different types of systems in the fixed service (FS) operate on a primary basis in the band mentioned incon
4、sidering a);c) that BSS (sound) systems are being planned for early implementation in the band 1 452-1 492 MHz;d) that systems planned for implementation in the interim in the BSS (sound) are required to coordinate underResolution No. 33 (WARC-79) of the World Administrative Radio Conference (Geneva
5、, 1979);e) that this Recommendation does not negate the ability of administrations to seek coordination underResolution No. 33 (WARC-79);f) that Resolution No. 522 (WARC-92) resolves that the ITU-R should study the means to be employed forcoordinating and avoiding mutual unacceptable interference be
6、tween BSS (sound) systems and the systems of otherservices. Resolution No. 528 (WARC-92) considers that it is necessary to ensure that the introduction of the BSS(sound) proceeds in a flexible and equitable manner, and invites the ITU-R to conduct the necessary studies ofinterference criteria to be
7、employed for sharing between the BSS (sound) and systems of other services;g) that Recommendation ITU-R M.1142 recommends threshold levels of power flux-density (pfd) at the surfaceof the Earth for coordination of geostationary space stations in the mobile-satellite service (MSS) with similar analog
8、ueand digital systems of the fixed service for some Regions in the adjacent band 1 492-1 530 MHz;h) that a digital signal from a geostationary space station in the MSS, and a digital signal of the same pfd from ageostationary space station in the BSS (sound) in some cases will have a similar interfe
9、ring effect on a receiving stationin the fixed service;j) that, with the use of sound broadcasting receivers with low-gain broadband antennas, the spacing ofgeostationary BSS (sound) space stations intended to provide regional service using relatively large spot beams will beof the order of 60 or gr
10、eater;k) that existing point-to-multipoint (P-MP) systems were designed for economic rural telephony implementationand typically are characterized as having low fade margins,_*The Administrations of Saudi Arabia, Burkina Faso, United Arab Emirates and Iran (Islamic Republic of) reserved their opinio
11、non this Recommendation.*This Recommendation should be brought to the attention of Radiocommunication Study Group 8 (Working Parties 8A and 8B)and Radiocommunication Study Group 10 (Working Party 10-11S).*This Recommendation should be reviewed by Radiocommunication Study Group 9 before being conside
12、red by a futurecompetent Radiocommunication Conference.2 Rec. ITU-R F.1338recommends1 that for BSS (sound) geostationary space stations with orbital spacing of 60 or greater, the following pfdlevels at the surface of the Earth may be applied as coordination thresholds with respect to stations in the
13、 FS operating inthe band 1 452-1 492 MHz (see Notes 1, 2, 4 and 5):1.1 for digital FS systems:128 dB(W/m2) in a 1 MHz band for 0 5128 + 0.5 ( 5) dB(W/m2) in a 1 MHz band for 5 25118 dB(W/m2) in a 1 MHz band for 25 901.2 for analogue FS systems:152 dB(W/m2) in a 4 kHz band for 0 5152 + 0.5 ( 5) dB(W/
14、m2) in a 4 kHz band for 5 25142 dB(W/m2) in a 4 kHz band for 25 90where is the angle of arrival (degrees) above the horizontal plane, and the pfd and angles of arrival are those thatwould be obtained under free space propagation conditions;2 that, for FS systems where a small percentage of routes or
15、 hops can tolerate additional performancedegradation, pfd values somewhat higher than those given in recommends 1 may be able to be tolerated (see Note 3);3 that, for FS systems that need to conform to performance and availability objectives for individual links(e.g. for customer or local grade syst
16、ems), pfd values somewhat lower than those given in recommends 1 may berequired to provide adequate protection (see Note 3);4 that the following Notes should form part of this Recommendation:NOTE 1 The pfd thresholds specified in recommends 1 pertain to situations where there is any overlap between
17、thenecessary bandwidths of the subject frequency assignments.NOTE 2 This Recommendation provides guidance on pfd coordination thresholds derived from a wide range of FSsystem parameters. It represents a compromise between the need to ensure adequate protection for existing and plannedFS stations and
18、 the desire to facilitate sharing of the band with BSS (sound) systems.NOTE 3 In the cases of recommends 2 and 3, administrations may determine the appropriate pfd levels at which toinitiate coordination.NOTE 4 Annex 1 provides guidance concerning additional technical and operational considerations
19、that may be takeninto account to facilitate coordination.NOTE 5 Further studies should be undertaken to continue the development of sharing methodologies and systemcharacteristics to be applied in the 1 452-1 492 MHz band.NOTE 6 This Recommendation takes into consideration the provisions of No. S5.3
20、47 of the RR.ANNEX 1Fixed system considerations that may facilitate successful coordinationFixed radio-relay systems may be either analogue or digital. Many are mature systems which have been designed to takeadvantage of known topographical features, equipment parameters and propagation characterist
21、ics. The followingsystem parameters or mitigation techniques should be reviewed and used to the extent practical towards achievingsuccessful coordination, especially in the planning and implementation of new systems in the fixed service.Rec. ITU-R F.1338 31 Antenna considerations1.1 Antenna orientat
22、ion1.1.1 Existing stationsIn the establishment of the coordination threshold levels in this Recommendation, the orientation of the receivingantennas with respect to the interfering satellites is not specifically taken into account. In detailed coordination, thisfactor may provide additional signific
23、ant protection for some receiving stations in the FS.1.1.2 New stationsIn the case of receiving omnidirectional antennas of P-MP central stations, improved side-lobe discrimination maycontribute to a reduction of BSS interference.In the case of directional (e.g. parabolic) FS receive antennas, it sh
24、ould be noted that, where practicable, the use ofantennas with larger gain will contribute to the reduction of fade margin loss due to BSS interference. In addition, whenthe direction towards a BSS space station is somewhat different from the direction of the desired signal, a certain degreesoffset
25、of the antenna direction away from the direction towards the BSS space station may contribute to the reduction offade margin loss due to BSS interference. An optimum offset angle will depend on the antenna pattern, separation angleand BSS interference level. This improvement will become greater if c
26、oupled with the use of an antenna withlarger gain.Annex 2 to Recommendation ITU-R F.1249 can be used for estimating the separation angle between the FS antennadirection and the direction towards the BSS space station taking into account atmospheric refraction.1.2 Orbital avoidance by planned station
27、sDiscrimination can be achieved by ensuring that substantial off-axis angles are provided between the received antennaboresights of future fixed stations and the geostationary-satellite orbit.1.3 Polarization discriminationIn situations where the antennas of fixed systems use different polarizations
28、 (e.g. linear) than those employed by BSS(sound) systems (i.e. circular), polarization discrimination (up to 3 dB) may be available in the case of mainbeam-to-mainbeam coupling of the FS antenna and the BSS space station antenna (see Recommendation ITU-R F.1245).2 Receiver/transmitter considerations
29、2.1 Frequency offsetDiscrimination can be obtained by offsetting channel frequencies of receiving fixed stations and transmitting BSS(sound) space stations, including minor changes to channel allocation consistent with the channel plans of the FS.Interference may be at acceptable levels in cases whe
30、re the necessary bandwidths of the BSS (sound) space station andfixed station assignments do not overlap. It should be noted that frequency offset is not effective when either the BSS(sound) or FS signal passband characteristics are relatively flat.2.2 Additional allowance for interferenceIn probabi
31、listic sharing studies for the determination of coordination threshold level given in recommends 1, anallowance of 1 dB has been assumed for a reduction in the fade margin, which has a corresponding impact on systemavailability and performance of FS systems (but this matter requires further study). However, improved sharing and asuccessful coordination may be obtained at the expense of fade margin by increasing the allowance for interference fromBSS (sound) space stations, and taking into account all factors contributing to the total or overall system availability.
