1、Rec. ITU-R F.1403 1RECOMMENDATION ITU-R F.1403POWER FLUX-DENSITY CRITERIA IN ITU-R RECOMMENDATIONS FORPROTECTION OF SYSTEMS IN THE FIXED SERVICE SHAREDWITH SPACE STATIONS OF VARIOUS SPACE SERVICES(Questions ITU-R 111/9, ITU-R 113/9, ITU-R 115/9, ITU-R 116/9, ITU-R 118/9 and ITU-R 201/9)(1999)Rec. IT
2、U-R F.1403The ITU Radiocommunication Assembly,consideringa) that the fixed service (FS) shares many frequency bands on a co-primary basis with space radiocommunicationservices such as the fixed-satellite, broadcasting-satellite, mobile-satellite and space science services;b) that criteria for the po
3、wer flux-density (pfd) at the surface of the Earth produced by space stations of spaceservices have been developed in order to control the interference into systems in the FS in the frequency bands sharedwith the space-to-Earth direction of these space services;c) that these criteria are mainly expr
4、essed as hard limits on pfd produced by space stations but when it is notpracticable, as coordination thresholds;d) that in some cases of interference assessment from non-geostationary (non-GSO) satellites into digital systemsin the FS in the 1-3 GHz range, coordination thresholds have been expresse
5、d in terms of fractional degradation inperformance (FDP);e) that various pfd criteria have been established since 1963 when certain frequency bands were allocated for thefirst time on a shared basis to the FS and the fixed-satellite service (FSS);f) that a number of methodologies for interference as
6、sessment have been developed in order to derive appropriatepfd criteria;g) that it is important to review the principles and advice which were incorporated in these methodologies,recommends1 that Recommendations ITU-R SF.358, ITU-R SF.1005 and ITU-R SF.1008 should be referred to for thepfd limits on
7、 space stations (mainly GSO) in the FSS;2 that Recommendation ITU-R SF.1320 should be referred to for the pfd limits on non-GSO space stations in theFSS used for feeder links of systems in the mobile-satellite service (MSS);3 that Recommendation ITU-R SA.1273 should be referred to for pfd limits on
8、space stations in space scienceservices in the 2 GHz bands;4 that Recommendations ITU-R M.1141, ITU-R M.1142, ITU-R M.1143 and ITU-R F.1246 should be referredto for coordination thresholds for frequency assignments to GSO and non-GSO space stations in the MSS in the1-3 GHz frequency range;5 that Rec
9、ommendation ITU-R F.1338 should be referred to for coordination thresholds for frequencyassignments to space stations in the broadcasting-satellite service (BSS) (sound) in the band 1 452-1 492 MHz;6 that Recommendations ITU-R F.1107 and ITU-R F.1108 should be referred to for the methodology forasse
10、ssment of interference from GSO and non-GSO space stations into systems in the FS;7 that Annex 1 should be referred to for the historical evolution of pfd criteria in ITU-R Recommendations forprotection of systems in the FS shared with space stations of various space services, which might be used as
11、 guidance forfuture studies on pfd criteria in various sharing situations.2 Rec. ITU-R F.1403ANNEX 1Historical evolution of pfd criteria in ITU-R Recommendationsfor protection of systems in the FS1 IntroductionPower flux-density at the Earths surface produced by space stations is an important factor
12、 for consideration in order toprotect systems in the FS from emissions of space stations sharing the same frequency bands. NumerousITU-R Recommendations have been established since 1963 dealing with this matter.Some Recommendations give hard limits on pfd. This facilitates frequency sharing, because
13、 individual coordination isnot required. But in some cases, it is difficult to establish hard limits, because no such limits can be found whichadequately protect the FS and, at the same time, do not place undue constraints on system design of space services. Insuch cases, Recommendations present coo
14、rdination thresholds and, if the pfd exceeds the coordination threshold,individual coordination is required with the affected administrations.In addition to the pfd, a concept of FDP was introduced in Recommendation ITU-R F.1108 in order to assess the effectsof interference from non-GSO satellites i
15、nto the FS.This Annex presents a historical evolution of pfd criteria adopted in various ITU-R Recommendations, many of whichhave been incorporated into the Radio Regulations (RR).2 Power flux-density limits on FSS space stationsPower flux-density limits on space stations in the FSS are recommended
16、in Recommendation ITU-R SF.358. It was in1963 that the first version of this Recommendation was developed. It took more than twenty years before thisRecommendation was almost finalized. It is applicable to both GSO and non-GSO space stations. However, it should benoted that only a limited number of
17、non-GSO space stations were assumed in confirming the applicability of thisRecommendation. Therefore, Recommendation ITU-R SF.358 should be regarded as applicable mainly to GSO spacestations and, if a large number of non-GSO space stations are involved, a separate consideration is necessary (see, fo
18、rexample, Recommendation ITU-R SF.1320).A detailed history about Recommendation ITU-R SF. 358 is given in Appendix 1 to Annex 1.3 FSS in bidirectional band usage and use by FSS space stations of orbits slightlyinclined with respect to the GSOThe coexistence of the FS with the FSS was planned by the
19、1963 Extraordinary Administrative Radio Conference (1963EARC) for unidirectional FSS transmissions and for GSO space stations. As a result, the permissible interference fromthe FSS was nearly invariant with time, except for propagation anomalies, and was generated from transmitting spacestations or
20、from transmitting earth stations.However, in order to increase the capacity of the FSS and to increase the longevity of the space segment, the use ofbidirectional transmission was considered for additional frequencies, and the use of slightly inclined orbits was alsostudied to save fuel and increase
21、 the useful life of the space stations.The benefits to the FSS of additional frequencies through the use of bidirectional transmission comes at the expense ofmore interference sources for both the FS and the FSS, and the use of slightly inclined orbits comes at the risk ofincreasing the number of fi
22、xed receivers exposed to near direct interference from transmitting space stations.Rec. ITU-R F.1403 33.1 Recommendation ITU-R SF.1005 (Geneva, 1993)The sharing criteria that were established by the 1963 EARC assumed that the aggregate permissible interference intothe model hypothetical reference ci
23、rcuit was small in comparison to the total noise of the system, and in fact, it could beaccommodated within the total noise budget of existing systems without making any changes to systems alreadydeployed throughout the world. Specifically, the permissible interference into fixed receivers from tran
24、smitting spacestations could effectively be limited by controlling the pfd at the surface of the Earth, and the interference fromtransmitting earth stations could be controlled by limiting the e.i.r.p. at the horizon. The limits on the pfd and the e.i.r.p.could satisfy the assumption of small permis
25、sible interference, but allow the effective development of the FSS for thebenefit of satellite technology throughout the world.The use of bidirectional transmission by the FSS increases the interference sources; as a result, the assumption that thepermissible interference from the FSS should be smal
26、l could not be maintained without additional restrictions on theFSS. The additional restrictions, that were developed in Recommendation ITU-R SF.1005 Sharing between the fixedservice and the fixed-satellite service with bidirectional usage in bands above 10 GHz currently unidirectionallyallocated (w
27、hich is based on ex-CCIR Report 1005 developed in 1986), were that bidirectional operation would belimited for frequencies above 10 GHz; the pfd for angles of arrival within 5 above the horizon and the interference fromtransmitting earth stations should be lowered by 7 dB, 5 dB, and 3 dB for frequen
28、cy bands, 10-15.4 GHz, 15.4-20 GHz,and above 20 GHz respectively; and for angles of arrival above 25 the pfd limits of Table 1 of Recommenda-tion ITU-R SF.358 should continue to apply.The application of bidirectional usage can be introduced with less interference impact on the FS provided that the F
29、SSuses transmitting earth stations with high elevation angles ( 40 ), spot beams of approximately 2 , and does notextensively use the GSO.3.2 Recommendation ITU-R SF.1008 (Geneva, 1994)The coexistence of the FSS and the FS has taken place successfully for the last three decades mostly for space stat
30、ionslocated in their nominal GSO locations. The probability that a FS receiver will intersect the GSO is low, and theprobability that a transmitting space station will be located at that orbital location is significantly lower. As a result, theaggregate interference that the model radio-relay system
31、 is expected to receive is mostly from a single near, directexposure and side-lobe interference from the rest of the visible space stations in the GSO.However, in order to keep the space stations in their nominal orbital positions fuel needs to be expanded, andparticularly, significant fuel needs to
32、 be used for north-south station-keeping. In fact, the lifetime of the space segmentmay be determined by the availability of fuel. If the north-south station-keeping was to be relaxed, the longevity of spacestations can be extended, but the resulting inclination of the orbit would result in more ter
33、restrial receivers exposed tonear direct interference even though the duration of the exposure would be a fraction of the 24 h period, and the totalaverage interference of the model hypothetical reference circuit may not increase.The portion of the 24 h period during which the terrestrial receiver i
34、s exposed to main lobe interference will result insignificant decrease in the thermal noise fade margin, and during these periods the receiver will be susceptible to slowlyvarying, non-dispersive, shallow fades. These fades can occur sufficiently frequently to make the affected receiverunavailable f
35、or an unacceptable amount of time. Recommendation ITU-R SF.615 provides the objectives for networkunavailabilities from all sources of interference, and the contribution of the expected unavailability from even a fewexposed receivers will exceed the aforementioned objectives by an order of magnitude
36、. As a result, the receiverssusceptible to main-lobe interference will have to be relocated in order to preserve the performance of the system.Recommendation ITU-R SF.1008 Possible use by space stations in the FSS of orbits slightly inclined with respect tothe GSO in bands shared with the fixed serv
37、ice, limits the amount of inclination to less than 5 without imposing anyadditional restrictions on the FSS. The slight inclination of the orbit limits the additional terrestrial receivers that areexposed to main-lobe interference, and even though the number of affected stations increases with latit
38、ude, the numberof susceptible receivers for latitudes as high as 60 is less than a few for a 50-hop system. However, for inclinationsgreater than 5 , the number of affected stations increases linearly, and a back-off on the pfd is recommended whichincreases linearly between five and ten degrees incl
39、ination, and reaches a maximum of 20 dB back-off at an inclinationof 10 .4 Rec. ITU-R F.1403Finally, the inclination of the orbit may be designed at the planning stage of the satellite, and a satellite may be injectedinto an inclined orbit such that the lifetime of the satellite is maximized while m
40、inimizing the amount of the inclination,and thus, the impact on the FS and the need for tracking is reduced.4 Power flux-density limits on BSS space stations in the 12 GHz bandThe 1977 World Broadcasting-Satellite Administrative Radio Conference (WARC SAT-77) established the Regions 1and 3 Plan for
41、the BSS in the bands 11.7-12.2 GHz (in Region 3) and 11.7-12.5 GHz (in Region 1). The 1983 RegionalAdministrative Radio Conference (RARC-83) established the Region 2 Plan for the BSS in the band 12.2-12.7 GHz.Various parameters of BSS space stations were stipulated in the Plan. These frequency bands
42、 are shared with the FS.Therefore, it is necessary in the planning of FS systems to take due account of the BSS Plan and not to cause anyharmful interference to BSS receiving earth stations.When any change is made to the BSS Plan, there is a risk that a BSS space station in a new orbital location or
43、 at a newfrequency assignment may cause unacceptable interference to existing FS systems. For this purpose, Annex 1 to RRAppendix S30 stipulates limits on the pfd to protect the terrestrial services in all three Regions.5 New allocations to various space radiocommunication services by WARC-92The Wor
44、ld Administrative Radio Conference (WARC-92) was held in 1992 in Malaga-Torremolinos for dealing withfrequency allocations in certain parts of the spectrum. This Conference allocated many frequency bands to various spaceradiocommunication services on a shared basis with the FS. It made the frequency
45、 sharing situations very muchcomplicated and invited the ITU-R to carry out urgent studies to establish appropriate sharing criteria.5.1 Allocation to BSS for HDTV near 20 GHzWARC-92 allocated the band 21.4-22 GHz to the BSS in Regions 1 and 3 on a shared basis with the FS and the band17.3-17.8 GHz
46、to the BSS in Region 2, out of which the band 17.7-17.8 GHz is shared with the FS. These allocations tothe BSS shall come into effect on 1 April 2007 (see RR Nos. S5.517 and S5.530).Resolution 525 (WARC-92) specifies the conditions for the use of the band 21.4- 22 GHz in Regions 1 and 3 by the BSSaf
47、ter that date and on an interim basis prior to that date. This Resolution gives the values of pfd at the Earths surfaceproduced by emissions from a space station of an operational BSS (HDTV) system before 1 April 2007, as coordinationthresholds. These values are identical to the values which were gi
48、ven in Recommendation ITU-R F.760 that had beendeveloped by Radiocommunication Study Group 9 just prior to the WARC-92.Recommendation ITU-R F.760 examines the in-beam interference at low angles of arrival and off-beam interference athigh angles of arrival to a 64-QAM FS receiver. After considering c
49、orrelation of rain fading between wanted andinterfering signals, the Recommendation arrives at the proposed pfd values. This was the first case in which the values inan ITU-R Recommendation were incorporated into a Resolution attached to the RR as coordination thresholds.5.2 Allocation to BSS (sound) in the 1-3 GHz rangeWARC-92 allocated the band 1 452-1 492 MHz to the BSS (sound) on a worldwide basis (except for one administration,see RR No. S5.344). In addition, the bands 2 310-2 360 MHz and 2 535-2 655 MHz were also allocated to the BSS(sound) for use in certain countries (see RR Nos.
