1、Rec. ITU-R B0.1444 1 RECOMMENDATION ITU-R BO. 1444* Protection of the BSS in the 12 GHz band and associated feeder links in the 17 GHz band from interference caused by non-GSO FSS systems (Question ITU-R 223/11) (2000) The ITU Radiocommunication Assembly, considering a) that the bands 11.7-12.5 GHz
2、in Region 1, 12.2-12.7 GHz in Region 2 and 11.7-12.2 GHz in Region 3 are allocated to the BSS; b) that the BSS in the above bands is subject to the Plans in RR Appendix 30; c) that the bands 17.3-17.8 GHz in Region 2 and 17.3-18.1 GHz in Regions 1 and 3 are allocated to the feeder links of the BSS;
3、d) that the feeder links of the BSS in the above bands are subject to the Plans in RR Appendix 30A; e) that the band 12.5-12.75 GHz in Region 3 is also allocated to the BSS; f) that the band 17.8-1 8.1 GHz in Region 2 is also allocated to the feeder links of the BSS; g) that WRC-97 allocated the ban
4、ds 11.7-12.5 GHz in Region 1, 12.2-12.7 GHz in Region 2, 11.7-12.2 GHz and 12.5-12.75 GHz in Region 3 to the non-GSO FSS (space-to-Earth) and 17.3- 17.8 GHz in Regions 1 and 3 and 17.8-18.1 GHz in Regions 1,2 and 3 to the non-GSO FSS (Earth- to-space) subject to the provisions of Resolution 538 (WRC
5、-97); h) that emissions fi-om the stations of non-GSO satellite systems may result in interference to BSS networks and associated feeder links when these networks operate in the same frequency bands; j) that RR No. 22.2 states that non-GSO satellite systems shall not cause unacceptable interference
6、to GSO satellite systems in the FSS and BSS operating in accordance with the RR; k) that WRC-97 adopted provisional equivalent power flux-density (epfd) limits to quantifj the level of unacceptable non-GSO interference and requested ITU-R to review these limits in order to ensure appropriate protect
7、ion of the Plans and their fbture modifications; 1) that there exist criteria to protect the BSS networks and associated feeder links fi-om other such networks operating in the same regional plan or in another Regional Plan (RR Appendix 30, Annex 1 and RR Appendix 30A, Annex 1); * Radiocommunication
8、 Study Group 6 made editorial amendments to this Recommendation in 2001 in accordance with Resolution ITU-R 44. 2 Rec. ITU-R B0.1444 m) that there exist criteria to protect the BSS networks fi-om FSS networks in another Region (RR Appendix 30, Annex 4) and to protect the associated feeder links fi-o
9、m FSS networks in the same or in another Region (RR Appendix 30A, Annex 4); n) links fi-om interference caused by non-GSO FSS systems; that there is a need to define criteria to protect a network in the BSS and associated feeder 0) that the harmonious development of non-GSO FSS systems and GSO BSS a
10、nd associated feeder-link networks requires that the conditions under which the sharing would be feasible should be identified as soon as possible; P) is to be ensured, that the integrity of the Plans in RR Appendices 30 and 30A and their future modifications considering further a) that the BSS and
11、associated feeder-link system designer should be able to control the overall performance of a network and to provide a quality of service that meets its CINperformance objectives; b) that to allow an operator to exercise control over the quality of service, there needs to be a limit on the aggregate
12、 interference a network must be able to tolerate fi-om emissions of all other networks; c) that in order to facilitate the introduction of non-GSO FSS systems in accordance with the provisions of RRArticle 22, it is necessary to establish sharing criteria that are applicable to individual non-GSO FS
13、S systems; d) that in frequency bands above 10 GHz where very high propagation attenuation may occur for short periods of time, it may be desirable for GSO and non-GSO systems to make use of some form of fade compensation; e) that in interference situations involving non-GSO systems, BSS and associa
14、ted feeder-link networks are potentially exposed to high levels of interference for short periods of time which could affect the performance or availability of these networks; f) that short-term interference events may cause a loss of video picture continuity or other unstable conditions in digital
15、BSS transmissions which may cause a degradation or loss of service for periods longer than interference events; g) that in interference situations involving non-GSO systems, B SS networks and associated feeder links are potentially exposed to low levels of interference for long periods of time which
16、 could degrade the performance or availability of those networks; h) that the performance and availability of an operating GSO-BSS system and its associated feeder links are degraded by external interfering noise contributions which may be steady state or of a statistical nature; j) other systems in
17、cluding non-GSO FSS systems that share the same band; that such degradations may be due to propagation anomalies, other GSO networks and Rec. ITU-R B0.1444 3 k) that emissions from the earth stations as well as from the space station of a satellite network (GSO BSS and associated feeder links or non
18、-GSO FSS) in those bands may result in interference to another such network when both networks operate in the same bands; 1) that a methodology is required to allow an accurate assessment of the time varying impact of epfd and apfd limits for non-GSO FSS networks on the performance of GSO BSS networ
19、ks and associated feeder links; m) that would provide suitable protection of the GSO BSS and associated feeder links, that the methodology would facilitate the determination of appropriate epfd and apfd limits recommends 1 that for a GSO BSS network in the 12 GHz band and its associated feeder links
20、 in the 17 GHz band, the aggregate inter-network interference caused by the earth and space station emissions of all non-GSO FSS satellite networks operating in the same frequency band, should: 1.1 be responsible for at most 10% of the time allowance(s) for unavailability of the given CIN value(s) a
21、s specified in the performance objectives of the desired network, where N is the total noise level in the noise bandwidth associated with the wanted carrier including all other non-time-varying sources of interference; 1.2 and associated feeder-link network under clear-sky conditions (see Note 2); n
22、ot lead to a loss of video picture continuity (see Note 1) in the desired digital GSO BSS 2 that epfd limits as defined in RR Article 22 and applicable respectively to non-GSO FSS systems to be operated in the 12 GHz bands shared with BSS and in the 17 GHz frequency bands shared with BSS feeder link
23、s be derived and specified in such a way: 2.1 representative GSO BSS and associated feeder-link system characteristics, as provided in Annex 1 ; that they satisfj the criteria in recommends 1.1 and 1.2 when applied to a set of 2.2 that the apportionment of the aggregate interference allowance specif
24、ied in recommends 1.1 and 1.2 to derive single entry limits be based on the effective number of non-GSO FSS systems that are anticipated to share the same frequency bands; 2.3 range of representative GSO receiving antenna sizes (see Note 3); that these limits are specified by continuous curves of cu
25、mulative density function for a 3 that the methodologies given in Annexes 2 and 3, in connection with an appropriate assumed number of non-GSO FSS systems, be applied for assessing the impact on the GSO BSS in the 12 GHz band and the associated feeder links in the 17 GHz band of epfd and apfd limits
26、 applicable to the non-GSO FSS (see Note 4); 4 recommends 1.2 are satisfied; that the methodology described in Annex4 be used to assess if the provisions of 4 Rec. ITU-R B0.1444 5 that the following Notes form part of the Recommendation. NOTE 1 -A loss of MPEG video picture continuity occurs when th
27、e BER of the demodulated MPEG video bit stream is sufficiently high to cause the associated video MPEG decoder to cease to provide one or more pictures. This condition typically results in the initiation of error concealment techniques by the video decoder, such as the presentation of the last avail
28、able MPEG picture (freeze frame), presentation of an all black picture, or other techniques. NOTE 2 - Administrations were requested to indicate the difference (dB) between the C/(N+ I) required at operating threshold, which is found on line 13 of the database spreadsheet, and the loss of video pict
29、ure continuity performance point for each link. If this information is not provided by the responsible administration, a default value of 1.5 dB will be assumed. NOTE 3 - Further study is required to ensure that, to the extent possible, these limits are consistent with the protection levels currentl
30、y afforded to the Plans in RR Appendices 30 and 30A and their future modifications. NOTE 4 - Calculations were carried out to establish the consistency of the results between the two methodologies. It was found that the two methods gave consistent results. However, it was found that in some cases th
31、ere are significant differences in the unavailability calculated by the two programs. Detailed studies that were performed demonstrated that differences between the two programs were encountered when analysing links using large earth stations antenna sizes (i.e. 120 cm and larger). The reason for th
32、is difference may be related to the link degradation resulting from the epfd limit for 100% of the time being close to the available degradation in the link. Administrations using these software packages should pay special attention to this finding. ANNEX 1 BSS system characteristics The database wh
33、ich is contained in this Annex consists of characteristics of operational and planned GSO BSS networks and the associated feeder links provided in response to Circular Letters CR-92 and CR-1 16 for the purpose of arriving at recommended epfd masks which will help in sharing studies between GSO BSS a
34、nd non-GSO FSS systems. This database in Excel format is available in electronic form at the ITU Website: Rec. ITU-R B0.1444 ANNEX 2 5 Methodology for analysing candidate epfd, and epfddown limits for the BSS and associated feeder-link bands 1 Overall principle The operation of the GSO carrier is de
35、fined by an operational threshold in terms of a given CIN. This operating threshold defines the CIN required for this link. Time-varying phenomena within the link can cause the CIN to fall below the operating threshold during a certain percentage of the time. This variation can be introduced by rain
36、 but also by non-GSO FSS systems. The present metho- dology aims at calculating the additional percentage of the outage time where the CIN falls under the operating threshold due to the interference fi-om non-GSO FSS systems. For this purpose, the application of recommends 1.1 calls for the calculat
37、ion of the relative increase in unavailability due to non-GSO FSS systems. This concept requires the calculation of both the unavailability without non-GSOs and the unavailability with non-GSOs in order to achieve their comparison. These two unavailabilities have to be calculated following exactly t
38、he same process in order for the comparison to be meaningful. 2 Need for a statistical approach Degradations in the link due to rain and non-GSO interference are random events in time which can be modelled using a probability density function (pdf) (the pdf for rain, i.e. the probability that rain f
39、ade equals a given value, can be derived fi-om Recommendation ITU-R P.618). If these phenomena are not modelled using their time-varying name, but instead by setting them as constants equal to the worst-case value, the result would overestimate the degradation on the link. It is therefore necessary
40、to statistically combine time-varying degradations that can lead the CIN below the operating threshold, i.e.: - rain attenuation on the uplink and on the downlink (their statistical description is included in Recommendation ITU-R P.618); - interference fi-om non-GSO FSS system(s) (their statistical
41、description is reflected in the epfhOwn mask). Each degradation source is assumed to be statistically independent fi-om the other. This means that the occurrence of one phenomena at a given amount has no correlation with the other occurrence of the other at the same time. 6 Rec. ITU-R B0.1444 3 Deta
42、iled principle Step I: Generate all possible combinations of each single degradation source and calculate the associated probability of occurrence, e.g. one combination will include: - uplink rain fade = 1 dB (single probability of occurrence = 0.25% of the time); - downlink rain fade = 0.5 dB (sing
43、le probability of occurrence = O. 15% of the time); - epfhOm = -175 dB(W/(m2 * 4 kHz) (single probability of occurrence = 1% of the time); - combined probability of occurrence = 0.25% x O. 15% x 1%. Step 2: For each of the above possible combinations, calculate the CIN by means of the link budgets i
44、n Annex 1 with the sources of degradation included. Step 3: Compare the CIN calculated with the operating threshold in order to determine if the link is available or not. Step 4: Sum up all the combined probabilities of occurrence corresponding to each combination in Step 1 that do not lead CIN unde
45、r operating threshold. The sum represents the probability that the link is available when both non-GSO interference and rain are considered. Step 5: Redo the process without using epfhom so as to calculate the GSO link availability without non-GSO interference. ANNEX 3 Monte Carlo implementation of
46、evaluation methodology 1 Introduction and summary Rain effects increase system unavailability as compared with clear-sky operations, by adding receiver system noise temperature. The presence of non-GSO system interference further increases system noise temperature and therefore system unavailability
47、. These and many other factors must be considered in evaluating numerical system availability in the presence of non-GSO. This Annex provides details of the Monte Carlo methodology proposed to evaluate the increase in BSS unavailability caused by non-GSO interference. First, a complete but also comp
48、lex equation for unavailability is derived. The equation is then simplified with approximations. A procedure for evaluating one of the simplified equations with Monte Carlo simulation is presented. An example result of using the simulation is discussed. Finally, derivation of the slope of the Transi
49、tion Rec. ITU-R B0.1444 7 Regime (B) for the proposed epfd masks is provided. The non-GSO interference is not faded by rain in this analysis. Appendix 1 to this Annex provides the derivation of the degradation equations with the non-GSO interference faded by rain. 2 Proposed evaluation methodology 2.1 Derivation of degradation equations with non-GSO interference not faded by rain In this Annex, noise, N, in a carrier-to-noise ratio, UN, refers to the sum of all unwanted powers for a particular situation, such as thermal noise, noise temperature increase fi-om rain, GSO interfe- rence, andor
