ITU-R S 1326-1997 Feasibility of Sharing between the Inter-Satellite Service and the Fixed-Satellite Service in the Frequency Band 50 4-51 4 GHz《50 4-51 4 GHz范围内星间服务和固定卫星共享的可行性》.pdf

1、STD-ITU-R RECMN S.132b-ENGL 1777 Li8552L2 0530440 152 = 1 Rec. ITU-R S.1326 RECOMMENDATION ITU-R S.1326 FEASIBILITY OF SHARING BETWEEN THE INTER-SATELLITE SERVICE AND THE FIXED-SATELLITE SERVICE IN THE FREQUENCY BAND 50.4-51.4 GHz (Question ITU-R 246/4) (1 997) The ITU Radiocommunication Assembly, c

2、onsidering a) that Resolution 643 of the World Radiocommunication Conference (Geneva, 1995) (WRC-95) instructs the ITU-R to carry out the necessary studies to identi the bands most suitable for the inter-satellite service (ISS) in the frequency range fiom 50 to 70 GHz in order to enable WRC-97 to ma

3、ke appropriate allocations to that service; b) service (FSS) (Earth-to-space), the fixed service (FS) and the mobile service; that the frequency band 50.4-51.4 GHz is currently allocated on a co-primary basis to the fmed-satellite c) co-frequency sharing with the FSS; d) that studies have been condu

4、cted into the feasibility of sharing between geostationary (GSO) futed-satellite networks operating in the Earth-to-space direction and inter-satellite links (ISL) of GSO and non-GSO satellite networks as detailed in Annex 1, that any potential new allocation to the ISS in this band would need to ta

5、ke into account the feasibility of recommendr 1 that sharing is made feasible in the band 50.4-51.4 GHz between the GSO FSS (Earth-to-space) and the ISS employing links between GSO satellites by employing certain mitigation techniques as detailed in Annex 1. NOTE 1 -Sharing is likely to be difficult

6、 between such FSS Earth-to-space links and ISL of non-GSO satellite networks. NOTE 2 - Further study is needed on the feasibility of sharing between non-GSO FSS or mobile satellite service (MSS) feeder link networks and the ISS, but that this is likely also to be difficult. ANNEX 1 This Annex analys

7、es the interference potential between GSO FSS networks and GSO ISS links, and between GSO FSS networks and non-GSO ISS links. The categories are sub-divided as follows: Case 1 - GSO ISS satellite transmitters (Txs) interfering into GSO FSS satellite receivers (Rxs). Case 2 - GSO FSS earth station Tx

8、s interfering into GSO ISS satellite Rxs. Case 3 - Non-GSO ISS satellite Txs interfering into GSO FSS satellite Rxs. Case 4 - GSO FSS earth station TXS interfering into non-GSO ISS satellite Rxs. For each case the maximum allowable interference power spectral density (PSD) was calculated. This was b

9、ased on either a percentage increase in the equivalent system noise temperature or from a received level of wanted carrier and a wanted carrier-to-noise ratio value to which a required interference margin is added. The maximum likely received interference PSD was then estimated using geometrical con

10、siderations. This permitted an estimate of the minimum margin of received interference power to the allowable interference power to be made. STD-ITU-R RECMN S-LjZb-ENGL L797 m 4855212 0530441 O79 RW. ITU-R S.1326 2 At the time of drafting this Recommendation there were no FSS systems notified to the

11、 Radiocommunication Bureau in the 50 GHz band. In order to investigate the potential for sharing between the FSS and the ISS it was necessary to frequency scale FSS system parameters notified in other bands. FSS system parameters were available at 30 GHz and it is possible to scale the FSS parameter

12、s from 30 to 50 GHz by making the necessary assumptions regarding increased atmospheric attenuation in he 50 GHz band. However, to minimize the assumptions used in scaling parameters, it was thought easier to scale down ISS link parameters from 60 to 30 GHz since they largely operate free of atmosph

13、eric attenuation effects. In scaling down ISS parameters it is noted that the FSS will use higher e.i.r.p.s at 50 GHz to overcome increased atmospheric attenuation and it is assumed that power control will be used by FSS earth stations at 50 GHz to avoid excess interference to the ISS in “clear air“

14、 conditions. The parameters used in the study are given in Tables 1 and 2. i Results of the analysis The analysis considers four geometric cases of interference potential. For each of the cases, the minimum margin of likely interference over allowable interference was estimated. Case 1 - GSO ISS sat

15、ellite transmitters (Txs) interfering into GSO FSS satellite receivers (Rus) Case 1 considers three scenarios of interference from GSO ISLs to GSO FSS satellites. These are outlined below with the geometry for the case shown in Fig. 1. For scenarios considered in Case I, the margin was found to be p

16、ositive indicating interference to FSS satellites jiom GSO ISS would be acceptable. The parameters used in the analysis for Case 1 are those of FSS network 1 from Table 1 and the GSO ISS Network from Table 2. The method assumed that the FSS satellite received a “wanted” carrier from an earth station

17、 operating at a minimum elevation angle of 10” and interference resulted to the FSS receiver from a GSO inter-satellite link. Also, the geocentric angle between a FSS satellite and an ISS satellite was assumed to be O. 1 O. For interference to the GSO FSS network 1, the minimum received carrier PSD

18、was calculated to be -183.98 dB(W/Hz) on the basis of an earth station operating to a GSO satellite at the minimum elevation angle of 10”. The required carrier-to-noise ratio for the FSS network is 5.8 dB, with a propagation margin of 2.5 dB. Assuming that a single entry interference limit of 6% of

19、thermal noise is applicable, the maximum allowable interference PSD is therefore calculated to be 20.52 dB lower than the minimum received carrier PSD, making the maximum allowable interference PSD for the GSO FSS network to be -204.5 dB(W/Hz). Scenario la: FSS satellite Rx near GSO ISS satellite Tx

20、, “minimum” distance In scenario la, the geocentric angle between the GSO FSS satellite Rx and the GSO ISL satellite Tx is assumed to be 0.1”, with the separation between the GSO ISS satellites assumed to be lo. This situation represents a minimum distance of interference between the ISS satellite a

21、nd the FSS satellite. Interference from the ISS antenna occurs via its main lobe, with the interference received by the FSS satellite antenna via its rear lobe. The maximum received interfering PSD was calculated to be -21 1.03 dB(WHz), giving the margin for scenario la to be 6.53 dB. Scenario I b:

22、FSS satellite Rx near GSO ISS satellite Ru, “minimum” distance In scenario lb, the geocentric angle between the GSO FSS satellite Rx and the GSO ISL satellite Tx is assumed to be 0.9, with the separation between the GSO ISS satellites assumed to be 1”. This scenario is similar to scenario la but rep

23、resents a reduced offset discrimination angle at the FSS satellite antenna. The margin for scenario lb was found to be 5.94 dB. Scenario IC: FSS satellite tx near GSO ISS satellite x. “maximum” distance The geocentric angle between the GSO FSS satellite Rx and the GSO ISL satellite Tx is assumed to

24、be 159.9”, with the separation between the GSO ISS satellites assumed to be 160. The case represents a maximum distance of interference between the ISS satellite and the FSS satellite. Interference is from the ISL antennas main lobe with interference received by the FSS antenna through its main lobe

25、. The margin for scenario 1 c was found to be 10.2 1 dB. STD-ITU-R RECMN S-132b-ENGL 1997 W Lid55212 0530442 T25 W 3 Rec. ITU-R S.1326 Case 2 - GSO FSS earth station Txs interfering into GSO ISS satellite Rxs Case 2 considers two scenarios of interference from GSO FSS earth stations to GSO ISLs. The

26、se are outlined below with the geometry for the case shown in Fig. 2. For the scenarios in Case 2, the margin was found to be positive in all but the extreme case of interference to vety long ISLs indicating that the interference to GSO ISLsflom the FSS would be acceptable. The parameters used in th

27、e analysis are those of FSS network 2 from Table 1 and the GSO ISS network from Table 2. For both of the scenarios of Case 2, the geocentric angle between the GSO ISS satellites is assumed to be 160“. The maximum allowable interference PSD was calculated using the formula: kTB where: k Boltzmanns co

28、nstant = -228.6 dB(J/K) T: system noise temperature, taken to be 6% of the notified system noise of 630 K B : reference bandwidth of 1 Hz. The maximum allowable interference PSD is calculated to be -212.83 dB(W/Hz). Scenario 20: FSS earth station Tx operating at an elevation angle of 90 to an FSS sa

29、tellite near a GSO ISS satellite Rx (represents minimum distance) For this scenario, the FSS earth station was assumed to be located at the equator and operating to a FSS satellite with an elevation angle of 90“. The geocentric angle between GSO FSS satellite and the GSO ISS satellite Rx was assumed

30、 to be O. 1 O. This situation represents the minimum separation distance between the earth station and the ISL. The maximum received interfering PSD was calculated to be -221.83 dB(W/Hz), giving the margin for scenario 2a as 9.0 dB. Scenario 2b: FSS earth station Tx operating at an elevation angle o

31、f 10to an FSS satellite near a GSO ISS satellite Rx (represents maximum distance) The earth station is assumed to be operating to the FSS satellite with an elevation angle of lo, with the geocentric angle between the GSO FSS satellite and the GSO ISS satellite Rx assumed to be 0.1. This configuratio

32、n represents the minimum antenna discrimination by a FSS earth station when causing interference, with the minimum discrimination at the GSO ISL antenna when receiving interference. The margin for scenario 2b was found to be negative at -13.82 dB. In order to make the margin positive, it was found t

33、hat the maximum geocentric angle between the ISLs must not exceed 152“, or the geocentric angle between the GSO FSS satellite and the GSO ISS satellite Rx link must be a minimum of 0.2“. Case 3 - Non-GSO ISS satellite Txs interfering into GSO FSS satellite Rxs Case 3 considers two scenarios of inter

34、ference from non-GSO ISS satellite Tx to GSO FSS satellites Tx. These are outlined below with the geometry for the case shown in Fig. 3. The parameters used in the analysis are those of FSS network 1 from Table 1 and the non-GSO ISS network from Table 2. To provide a minimum offset angle at the non-

35、GSO ISL when interfering into an GSO FSS satellite Rx, the case assumes that the inter-satellite link is between two adjacent non-GSO satellites communicating with each other in the same orbital plane. The maximum allowable interference PSD to GSO FSS satellites has been previously calculated for th

36、e GSO FSS network 1 (in Case 1) as -204.5 dB(W/Hz). For the scenarios considered in Case 3, the margin was found to be positive indicating interference to GSO FSS satellites from non-GSO ISS would be acceptable. Scenario 3a: Non-GSO ISS satellite Tx interfering with a GSO FSS satellite Rx at a minim

37、um separation distance. The interference is ISS satellite Tx antenna rear-lobe to FSS satellite x antenna main lobe This scenario considers an earth station operating to a FSS satellite with an elevation angle of 90, with the non-GSO ISS satellite located directly above the earth station. The situat

38、ion represents the minimum interference distance between the networks. The margin for scenario 3a was found to be 53.29 dB. - STD-ITU-R RECMN S.132b-ENGL 1337 m 4855212 0530443 Yb1 m Rec. ITU-R S.1326 4 Scenario 3b: Non-GSO ISS satellite Tx link antenna main lobe interfirence to GSO FSS satellite Rx

39、 This scenario considers interference from a non-GSO ISL through its main lobe to a GSO FSS satellite that is operating to an earth station which is at an elevation angle of 10”. The interference to the FSS satellite is received through the antennas “first“ side lobe region. The scenario represents

40、a maximum interference power received at the FSS satellite. The margin for scenario 3b was found to be 19.89 dB. Case 4 - GSO FSS earth station Txs interfering into non-GSO ISS satellite fis Case 4 considers two scenarios of interference from a GSO FSS earth station transmitter into a non-GSO ISL. T

41、hese are outlined below with the geometry for the case shown in Fig. 4. The parameters used in the analysis are those of FSS network 2 from Table 1 and the non-GSO ISS Network from Table 2. In the analysis, to provide the minimum offset angle at the non-GSO ISL when receiving interference fiom a FSS

42、 earth station, the inter-satellite link is taken to be fiom a non-GSO satellite communicating to another satellite two orbital planes away. The maximum allowable interference PSD was calculated using the formula: k TB where: k Boltzmanns constant = -228.6 dB(J/K) T: system noise temperature, taken

43、to be 6% of the notified system noise of 438 K B : reference bandwidth taken to be 1 Hz. The maximum allowable interference PSD was calculated to be -2 14.40 dB(W/Hz). For the scenarios in Cast? 4, the margin was found to range fiom -19.80 dB for a FSS earth station operating at elevation angle of 9

44、0 O to -25.70 dB for a FSS earth station operating at an elevation angle of I O 4 These were derived fiom a maximum allowable interference power based on an allowable increase in system noise temperature of 6%. If the interference could be considered to be short term, it would allow the maximum inte

45、rference power to be derivedpom an increase in system noise temperature of up to 1480%. This will increase the margins by 23.92 dB. However, the margin for scenario 4b will still be slightly negative at -1.78 de, concluding that unacceptable interference may be caused by FSS earth stations to non-GS

46、O ISLs. Scenario4a: GSO FSS earth station Txs interfering into non-GSO ISLs at a minimum separation distance. The interference is FSS earth station antenna main lobe to ISS satellite x antenna rear lobe , This scenario considers an FSS earth station operating to a GSO satellite with an elevation ang

47、le of 90”. Interference is through a FSS earh station antenna main lobe to an ISS satellite Rx antenna rear lobe. The margin for scenario 4a is found to be negative at -19.80 dB (for a protection ratio based on 6% of system noise temperature). If the interference can be considered to be short term,

48、it may be appropriate to base the protection ratio on up to 1480% of noise thereby increasing the maximum allowable interference by 23.92 dB, making the margin for scenario 4a to be 4.12 dB. Scenario4b: GSO FSS earth station Txs interfering into non-GSO ISLs at a minimum elevation angle. The interfe

49、rence is FSS earth station antenna main lobe to ISS satellite Rx antenna side lobe This scenario considers an earth station Tx operating to a FSS satellite with a minimum elevation angle elevation angle of 10. Interference is from the FSS earth station antenna main lobe to the ISS satellite Rx antenna side lobe. The margin for scenario 4b is found to be at -25.70 dB (for a protection ratio based on 6% of system noise temperature). If the interference is considered to be short term, it may be appropriate to base the protection ratio on up to 1480% of