1、230 CCIR RECMNx740 92 4855232 0538850 157 m Rec. 740 RECOMMENDATION 740 TECHNICAL COORDINATION METHODS FOR FMED-SATELLITE “WORKS (Question 49/4) (1 992) The CCIR, considering a between planned and existing networks; that during the planning stage of a satellite network it is necessary to calculate l
2、evels of potential interference b) Radio Regulations and Recommendations 738 and 739; that the methods to determine the need for coordination of satellite networks are given in Appendix 29 to the c of the potential for interference between satellite networks; that once the need for coordination has
3、been identified, it would be necessary to make a technical assessment 4 that the CCIR has reviewed various approaches to the management of the geostationary-satellite orbit; e) that the approach used in the detailed technical coordination process is left to the administrations concerned; f) the cond
4、itions for the operation of their respective networks: that if the potential interference exceeds the allowable criterion, the administrations concerned must agree on 8) networks of the fixed-satellite service; that Recommendations 466, 671, 483, 523 and 735 provide permissible levels of interferenc
5、e between h) that in certain cases there may be a need for multilateral coordination, recommends 1. that in undertaking detailed technical coordination of fixed-satellite networks, the techniques listed below and described in Annex 1 may be used, by agreement between the administrations concerned in
6、 the absence of any other mutually agreed approach: - carrier power technique; - power density averaging bandwidth technique; - isolation technique, 2. that Note 1 should be considered part of this Recommendation. Note 1 - Annexes 2,3 and 4 contain the methods for the detailed calculations of the ab
7、ove techniques. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR RECMNr740 92 W 4855232 0538853 O93 W Rec. 74 231 ANNEX1 Technical coordination methods for fixed-satellite networks 1. General approach For the purpose of this Annex,
8、 the network seeking access to the orbit is designated A. It is assumed that AT calculations, based on information as required under Appendix 4 of the Radio Regulations and as published by the IFRB for registered networks (a registered network is one whose assignments have been recorded in the IFRB
9、Master Register), for networks not yet registered but already Coordinated, and for networks which are in the process of being coordinated, have established the need to coordinate with networks B, C, D, etc. which may fall in any of the above categories. All such networks have precedence over the app
10、licants network A. 2. Coordination process The coordination process can, for purposes of discussion, be divided into three phases. The first involves the inspection of the actual or planned transmissions of the involved networks and an assessment of their interaction against “standard” interference
11、criteria. The second phase of the process is an investigation of potential changes to the transmission plan elements (transmission characteristics, frequency plans) or orbital locations which could lead to a solution of any interference problems identified in phase 1. Generally, the applicant admini
12、stration will tend to have more latitude in considering such changes to its network than the administration operating an existing system; however, phase 2 would not expect either network to consider the acceptance of serious constraints on its current or planned mode of operation, type, distribution
13、 and quality of service. This phase should, through very detailed consideration of all technical and operational parameters, be capable of resolving specific and apparently relatively severe interference situations. The third phase, if necessary, would be consideration and negotiation of system modi
14、fications and adjustments on either or both involved networks. Such changes may affect the quality and type of service and the future growth options of either or both networks. In dealing with the resolution of interference conditions it must be borne in mind that any specific solutions found for th
15、e two networks under consideration may generate or aggravate problems with other networks; this may be particularly significant when considering space station relocations. 3. Technical considerations Fundamentally, there are two initial facets to the coordination process: - agreement on acceptable i
16、nterference criteria; and - agreement on the calculations of the interference. CCIR Recommendations may be used for interference criteria but other criteria may be used by mutual acceptance. The calculations generally involve a translation of receiver output criteria to receiver input 0 criteria and
17、 the RF interference path parameters. Since many of the parameters amenable to modification are associated with the RF domain, it may be convenient to classify approaches to coordination in this domain, i.e. based on RF criteria. COPYRIGHT International Telecommunications Union/ITU Radiocommunicatio
18、nsLicensed by Information Handling ServicesCCIR RECMN*40 92 4855212 0518852 TZT 232 Rec. 740 3.1 Interference domains A first step in the coordination process is identification of the interference domains. Each band or band segment common to both networks for each satellite beam in the two space seg
19、ments must be identified. Within each such band or band segment, those portions over which the space station and earth station receiving sensitivities (G/T) and space station and earth station e.i.r.p. densities remain constant in either network are identified. This process yields all the interferen
20、ce domains. Certain portions of the spectrum may appear several times because they may represent intra-satellite frequency re-use. Where up-link frequencies and down-link frequencies or satellite beams or both may be paired in a variety of ways (switching of beam connectivity in a space station), al
21、l possible operational configurations need to be considered. Further, the number of domains will usually be bounded, at least in current space stations, by the transponder arrangement in the space stations and may, in simple space stations, encompass several or all transponders. Where two space stat
22、ions have single satellite antenna beams (i.e. common- coverage transmit and receive beams) and all their transponders have uniform charactenstics over the common frequency band there would be only one interference domain. 3.2 Coordination approaches The selection of the methods used to effect coord
23、ination is determined by agreement between the participating administrations. The characteristics of the affected networks and the potential severity of the interference will influence the choice of the approach to be used for coordination. Interference coordination can, in practice, be achieved wit
24、h a variety of techniques. Among these are: - the comparison of the rotal carrier power characteristics of transmissions with criteria of acceptable received interfering power; - the comparison of the power density characteristics of transmissions with criteria of acceptable received interfering pow
25、er density; - the comparison of available inter-network isolation (normalized inter-network coupling loss) with criteria of required isolation between transmissions (normalized wanted-to-unwanted carrier ratio). For the first case, RF criteria can be expressed as Z/N or CIZ and for the second case a
26、s ZdNo or CdZo where I is the interference power, N is the internal link noise power and C is the desired carrier power and subscript “o” indicates power - for modulations which are well defined and may be of any type, e.g. SCPC, analogue, digital, FMITV, etc.; - in frequency bands in which this app
27、roach has been extensively used. The mandatory information required under Appendix 4 of the Radio Regulations is not sufficient to serve as a basis for coordination under an ZIN or C/Z approach. It is necessary for the applicant administration to submit more detailed information on his network. Othe
28、r administrations having networks with which the need to coordinate has been established must also furnish more detailed information. To effect coordination using the UN or C/Z approaches requires a full exchange of Appendix 3 data including superscript information for each carrier type, earth-stati
29、on type and satellite antenna beam within all bands or band segments common to both networks; and where available, individual frequency plans. Since this information is adequate for the C/Z approach, it would appear desirable to proceed on this approach, since it provides a more accurate estimate of
30、 interference. COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Information Handling ServicesCCIR RECMN8740 92 = 4855232 0538853 966 Rec. 740 233 The interference domains must first be identified. For each of these it is necessary to identify the transmission (carr
31、ier) types which are used or are planned to be used in both networks. In the absence of known frequency plans the worst interference combination of the carriers of the two networks should be assumed. In most cases, this would correspond to frequency coincidence of the carriers. Where frequency plans
32、 are known, or where only one arrangement of transmissions in the two networks within a given interference domain is possible, the interference analyses are simplified. For each domain, interference from each transmission type of one network into each transmission type of the other is calculated for
33、 coincident frequency assignments (or, where available, for the actual or planned frequency assignments) in each direction (Le., from network A into network B and vice versu). Each interfering transmission is assumed to originate at the lowest-gain antenna of a transmitting earth station (i.e., the
34、one having the highest off-axis e.i.r.p.) which does or is expected to use it. When the interfering transmission occupies a bandwidth much less than that of the interfered-with transmission, it should be assumed that transmissions of the interfering type occupy, at appropriate intervals, the whole b
35、and occupied by the interfered-with transmission. It is then necessary to compare the resulting calculated values of C/Z with the mutually acceptable single entry values. If these calculations show that acceptable values of C/Z result in all cases, then a successful coordination has been effected. I
36、f the interference criteria are not satisfied in one or more cases, then each case must be individually considered. Where the criteria are only slightly exceeded, it may be agreed that these interference levels could be tolerated by either network. In particular, the applicant administration may dec
37、ide unilaterally that interference into its network, although somewhat exceeding the criteria value(s), would be acceptable and, if there is no other area of disagreement, it could claim immediately successful coordination. Otherwise, a number of measures may need to be considered in order to meet t
38、he mutually acceptable criteria, Annex 2 provides the method for calculating the C/Z for GSO satellite networks. 3.2.2 Power dens technique This technique may be most applicable to the foliowing cases: - in frequency bands in which satellite networks are in the early stages of development and in whi
39、ch the satellite population is small; - for modulations which have a nearly uniform power spectral density, e - where initial ATIT calculations result in values which are acceptable to each administration. This may be the case for some common domains between the networks: - where there is a consider
40、able degree of flexibility in one or both networks so that power density values can be modified. In this approach, the initial assessment of interference may be made using the Appendix 3 data for each of the interference domains. This assessment can identify the particular domains in which potential
41、 interference is most severe and also whether up-link or down-link interference is most dominant. Each party could use the IdNo values acceptable to him based on his carrier modulation types. It is possible that these calculations could result in mutually acceptable values of ZdNo, in which case a s
42、uccessfkl coordination would have been effected. If the ZdNo values are not acceptable, then several other steps may be taken. If up-link interference is the dominant source, changes in the up-link power densities and transmission gains may be made to reduce the mutual interference. Additionally, re
43、arrangement of accesses by band segments may be made Le., a modification of interference domains, so that a greater degree of homogeneity exists between the two networks, thus reducing the mutual interference. e COPYRIGHT International Telecommunications Union/ITU RadiocommunicationsLicensed by Info
44、rmation Handling ServicesCCIR RECMN*740 92 4855212 0518854 T2 234 Rec. 740 The average power density in a transponder can be used to determine a minimum practical satellite spacing which may be an effective measure of achievable satellite spacing in the coordination process. Since power of a transpo
45、nder is limited, the power density averaged over the transponder bandwidth is also limited. Using this average power density, a satellite spacing can be determined for a given interference criteria, taking into account expected inhomogeneities in traffic in detailed coordination between the networks
46、. This satellite spacing can be used in the coordination process as a basis for determining achievable satellite spacings. If power densities higher than this average power density exist in a portion of the bandwidth of the transponder, then power densities lower than the average must also exist in
47、other portions of the transponder bandwidth; a condition which can be used in a coordination process. It may also be appropriate to use reference or averaging bandwidths consistent with the carriers employed instead of the 4 kHz and 1 ME reference bandwidths of the Radio Regulations. These will gene
48、rally result in lower values of IdNo, and can facilitate the coordination process, particularly where narrow-band carriers in one satellite operate opposite wideband carriers in another satellite. In this case, a satellite spacing based upon narrow- band carrier interference criteria may be used to
49、obtain an acceptable interference criteria for the wideband carriers, thus avoiding detailed carrier frequency planning. Interference to narrow-band carriers from wideband carriers will be relatively uniform if the wideband carrier power density is relatively uniform. The techniques enumerated above have formed a basis for the development of a power density-averaging bandwidth method of determining interference between satellite networks. The method is based on providing a sufficient number of power density-averaging bandwidth data points so that the interference in any bandwidth of inte
