1、ERC REPORT 29 T European Radiocommunications Committee (ERC) -I._._,r -, .+. within the European Conference of Postai and Telecommunications Administrations (CEm % . COMPATIBILITY STUDY BETWEEN FIXED SERVICE OPERATING UNDER RR730 MOBILE SATELLITE SERVICE IN THE 1610-1626.5 MHz BAND AND Brussels, Jun
2、e 1994 CONTENTS 1. introduction 2. Interference from MES to Fixed Service 3. Interference fromFixed Service to MSS satellites 4. Interference from downlink MSS to Fixed Service 5. Conclusion Annex 1 : Interference fromm to German radio relays Annex 2 : Interference to ICO/MSS systems from German FS
3、systems Annex 3 : Interference to GEOMSS systems from German FS systems Annex 4 : Compatibility between MSS downlink and the FS in Germany Copyright 1994 the European Conference of Postai and Telecommunications Administrations (CEPT) STD-CEPT ERC REPORT 29-ENGL 3994 M 2326434 0015368 T27 Is ERC REPO
4、RT 29 Page 1 COMPATIBILITY STUDY BETWEEN FIXED SERVICE OPERATING UNDER RR730 MOBILE SATELLITE SERVICE IN THE 1610-1626.5 MHz BAND AND 1. INTRODUCTION WARC-92 (RR 731E) allocated the band 1610-1626.5 MHz on a primary basis to the Mobile Satellite Service (MSS) in the earth-tespace direction (uplink)
5、and the band 1613.8-1626.5 MHZ on a secondary basis to the MSS in the space to earth direction (downlink). This report presents the results of the study concerning the sharing between Fixed Service and MSS. RR730 gives primary allocation to Fixed Service in the following CEFT countries : Germany, Au
6、stria, Bulgaria, Spain, France, Hungary, Poland, Romania, Czech Republic and Slovakia. RR731E states that MSS stations shall not cause interference or claim protection from stations operating under RR730. Spain and France have been added to this footnote during WARC92. France has not planned any int
7、roduction of systems for the moment. All other countries are expected to withdraw equipment before MSS operations in 1996. Characteristics for MSS are not fully determined at the moment. Both TDMA and CDMA access techniques and both GSO and non GSO satellites are considered in the calculations, with
8、 technical data already available. MSS systems are referred to by name for ease of identification. According to RR731E, the MES maximum EIRP should be -15dBW/4kHz when sharing with systems operating under RR732 and -3dBW4 kHz elsewhere. For the time being, only the Iridium project intends to use a s
9、econdary status downlink allocation in the band 1616 MHz to 1626.5 MHz. 2. INTERFERENCE FROM MES TO FIXED SERVICE According to Germany and their experience from sharing between Inmarsat C and the fixed service, uiterference has sometimes occurred above 1626.5 MHz but the tactical RR systems, owing t
10、o their freedom in frequency selection, are able to deal with this interference. To give the order of magnitude of the interference, a very short calculation has been made in annex 1 and gives the following required separation distances : Main lobe : 33 km (CDMA) to 66 km (TDMA) Side lobe : 22 km (C
11、DMA) to 4.6 km OMA) Back lobe : 12 km (CDMA) to 30 km OMA) However, considering the low number of radio relays operating simultaneously in the 1610-1626.5 MHZ band, the likelihood of interference could be low when the MSS starts to develop. 3. INTERFERENCE FROM FIXED SERVICE TO MSS SATELLITES Calcul
12、ations carried out in this section have been made before knowing that German Radio Relays will be withdrawn before 1996. Thus, interference scenario considered was between a MSS satellite and a particular MES located close to Germany. It is likely that similar results would be obtained with other Eu
13、ropean countries operating Fixed Service according to R730. ERC REPORT 29 Page 2 Interference effects from the Fixed Service into MSS satellite receivers have been studied for example for GSO and Non- GSOIICO systems. Since the information on the number of simultaneous co-channel transmitting FS sta
14、tions could not be gathered, a single FS station was assumed to be transmitting ctFchanne1 with a particular mobile earth station. For a Non-GSO/ICO system, the worst case scenario of a spot beam covering both the FS and the MES location was chosen. The simulation consisted of calculating, at interv
15、als of 10 minutes, the interference from the FS station into the satellite which is providing service to the MES at that moment. The selection strategy for the satellite was to choose the one with minimum elevation angle 20 degrees. The elevation angle from the FS location to the selected satellite
16、was generally greater than O degrees thus affording some FS antenna discrimination. The duration of the simulation was 24 hours. It was also assumed that there was no azimuth discrimination between the satellite and the FS station. For the GSO case a system with four orbital locations visible to Ger
17、many was assumed. The results obtained for the GSO (TDMA) case show that at least one of the four satellites, which has low elevation angle towards Germany, will receive excessive interference in some of the spot beams covering the FS stations in Germany. For the Non-GSOIICO case the results show th
18、at the interference to the MSS uplink carrier from a given MES (operating in Germany) could exceed the protection criteria for 33 % of the time. However, it is important to notice that a small improvement in the protection criteria threshold (e.g. 3 dB) would reduce considerably the percentage time
19、of excess interference. Consideration of statistical factors associated with azimuthal pointing differences (extra FS antenna discrimination) and the probability of Co-channel operation between the FS and the MES would also help to ameliorate the interference effects. For CDMA MSS systems, considera
20、tion of their processing gain would also help lessen the interference effects. The calculations for the example cases are presented in annex 2 for the IC0 case and in annex 3 for the GSO case. - 4. INTERFERENCE FROM DOWNLINK MSS TO FIXED SERVICE Calculations have been carried out and show that the d
21、ifference between the maximum PFD for protection of the FS in Germany (given by RR2557, article 28) and the calculated PFD produced by the published satellite systems HIBLEO and HIBLEO-2 (e.g. Iridium) is in the range of 34 to 47 dB. These calculated results and the current RR specifications show th
22、at the frequenq sharing of FS systems and MSS systems in the 1613.8 - 1626.5 MHz band would be quite difficult for future operation of the MSS downlink. see annex 4 for detailed calculations Further studies should be undertaken by the MSS operators in cooperation with Administration of countries whi
23、ch will operate FS under RR730 after 1996, including the interference potential from PS transmitter into the MES receiver (e.g. MSS hand-held). 5. CONCLUSION Interference from MES to radio relays, when it occurs, will be solved on a national basis. There is also a potential risk that radio relays wi
24、ll interfere with MSS satellites. Interference from secondary MSS downlink emissions in this band are likely not to be tolerable. ERC REPORT 29 Page 3 ANNEX 1 INTERFERENCE FROM MES TO GERMAN RADIO RELAYS 1. TECHNICAL DATA ON TYPICAL GERMAN TACTICAL RADIO RELAY SYSTEM Che typical German Radio Relay s
25、ystem has the following characteristics : Frequency band : 1400- 1660 Output power : up to 1.2 W Noise figure : 8 dB max. IF bandwidth : 600 kHz Antenna gain : 19.5-22 dB Side lobe attenuation : 9 dB min Front to rear ratio : 18 dB min. Other tacticai Radio Relays used in this band have some very si
26、milar characteristics. However, their antenna sidelobe and backlobe attenuation are better. Hence, following calculations have to be understood as a worst case. 2. CO-CHANNEL INTERFERENCE FROM MSS TO FS It is possible to assess interference distance from various MSS systems to German fixed service.
27、Only Co-channel interference case will be studied, considering a mobile in the antenna mainlobe, sidelobe or backlobe. in calculations, we considered the CCIR interference criteria of a maximum 1 dB increasing of noise. This gives a noise to interference ratio of 6 dB. Multiple interferers scenarios
28、 would lead to some highest values but will not be considered for these rough calculations. Various MES power from CDMA or TDMA multiple access, LEO, IC0 or GSO space segment configurations have been computed. Interfering distances have been deduced from Ohura curves at 1500 MHz for open area, with
29、a mobile height of 1.5 m and a base height (RR height) of 30 m. Calculations are presented on the following page 3. RESULTS First, it should be noted that the space segment configuration (GSO, ICO, LEO) has no effect on the interference distance. On the other hand, TDMA multiple access, having an hi
30、gher power in the RR bandwidth, gives some more harmful interference than CDMA multiple access. Even with a better sidelobe and backlobe discrimination, interference would occur in all directions. Hence, the likelihood of interference could increase very quickly with the development of MSS in German
31、y. Precise figures on interference probability would require more information on the use of these military tactical radio relays. STD-CEPT ERC REPORT 29-ENGL 1994 ERC REPORT 29 Page 4 system GLOBALSTAR multiple access space segment MES EIRP (dBW) MES bandwidth (kHz) MES EIRP (dBW) in 600 kHz CDMA LE
32、O -2.2 1250 -5 RR receiver noise (dBW) -138 RR Max. interference level (dBW) -144 RR NA (dB) 6 RR antenna gain (dBi) Mainlobe 22 Sidelobe 13 Backlobe 2 required path loss (d) Mainlobe Sidelobe Backlobe Interference distance (km) Mainlobe Sidelobe Backlobe 161 152 141 38 27 16 111 2326414 0015371, 51
33、1 PI ODYSSEY CDMA I CO -0.5 5300 -10 -1 38 6 -1 44 22 13 2 1 56 1 47 136 33 22 12 IRIDIUM INMARSA INMARSA INMARSA T T T TDMA TDMA CDMA TDMA LEO GSO I CO I CO 6 8 -1 8 40 20 I O00 20 6 8 -3 8 -1 38 -1 38 -1 38 -1 38 6 6 6 6 -144 -1 44 -1 44 -144 22 22 22 22 13 13 13 13 2 2 2 2 172 174 163 174 163 165
34、 154 165 152 154 1 43 154 60 66 43 66 43 46 30 46 27 30 18 30 ERC REPORT 29 Page 5 ANNEX 2 INTERFERENCE TO ICOMSS SYSTEMS FROM GERMAN FS SYSTEMS 1. INTRODUCTION This annex analyses the interference which would be caused to ICOMSS systems from Co-primary FS systems in 1.6 GHz operating in Germany in
35、accordance with RR 730 until 1996. 2. SYSTEM PARAMETERS The ICOMSS system parameters, similar to that being considered for Inmassats fume hand-held system, are given in sub-annex 1. The system consists of 10 satellites in two intermediate circular orbits at 10,355 Kms inclined at 47.5 degrees. The s
36、alient parameters of German FS systems are given in Sub-annex 2. 3. METHODOLOGY Line of sight PS systems typically operate parallel to horizon and hence at O degree elevation angle. So if from a given terrestrial location the elevation angle to the IC0 satellite would be O degree, and the satellite
37、azimuth would coincide with the FS antenna azimuthal pointing, then the IC0 satellite would receive a direct interference hit from the FS transmitter. Por any off axis (elevation or azimuth) angles to the satellite the interference effects will be less. A representative extreme terrestrial location,
38、 of 54 N, 14 E, was chosen on the German territory for this case study. A FS station could be assumed to be located at this point. Since the worst case would relate to a spot covering both the PS and the MES location a typical MES location of 40 N, 14 E has been chosen. The MSS system is designed to
39、 provide service for elevation angles 20 degree. So at any given time instant it is assumed that out of the visible satellites only the one with minimum elevation angle 20 degree is providing service to the MES. The analytical process consists of determining the satellite with which the MES is opera
40、ting. Then, determining the elevation angle from the FS location to that particular satellite at that time instant. Then determining the off axis gain of PS antenna from Subannex 2 and the instantaneous slant range loss and hence compute the (C/I) at the input to the satellite receiver. Aprotection
41、criteria of a (CR) of 17.0 dB has been used to determine whether the interference is excessive or not. 4. RESULTS The results are given in Sub-annex 3. As can be seen the interference into a given MES uplink carrier exceeds the 17 dB criteria for 33 % of the day. STD*CEPT ERC REPORT 27-ENGL 1994 I 2
42、326434 0015373 374 B ERC REPORT 29 Page 6 The following points are important for the conclusion and should be kept in mind : * the analysis has considered interference from only one FS transmitter * no azimuthal pointing difference has been assumed for the FS antenna and the IC0 satellite direction.
43、 Only one FS trend line corresponding to the azimuth of the Subannex 3 would actuaily result in these interference levels - all other azimuthal directions should afford further discrimination - and, as a matter of fact, the MES will communicate alternatively with a satellite in different orbital pla
44、nes, leading to some azimuthal discrimination during part of the time. * the FS tactical systems operating in Germany have a tuning range of 400 MHZ. The possibility of excess interference into the MSS will occur only if the system in this worst case interference scenario is tuned in frequencies ove
45、rlapping with the 1610-1626.5 MHz band. * great part of the C/I values below 17 dB lie between 14 and 17dB. Therefore great part of the interference situations will have relatively small excess interference (I 7 = O 2 1 .,. . , ,. . .,. . ,. , . . ,. , , : : O O 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 1
46、6 17 18 19 20 21 22 2324 time (hours) Figure 3 : Time periods when C/I 17 From figure 3 we can conclude that the interference into a given MES uplink carrier exceeds the 17dB total interference allowance for 33% of the time. It is important to observe in figure 2 that great pari of the C/I values wh
47、ich are below 17dB lie between 14 and 17 dB. Thus, if the protection criteria is appropriately chosen in this range than the percentage time for excess interference could be minimized. STD-CEPT ERC REPORT 29-ENGL 3994 W 2326414 0035378 97b 14 7 10 15 ERC REPORT 29 Page 11 North STD*CEPT ERC REPORT 2
48、7-ENGL 1974 23264l4 0015380 524 ERC REPORT 29 Page 13 3. CONCLUSION Fromthe CA results in this case study we can conclude that the GE0 satellite located at 55 W will not be able to operate some of the spot beams which covers Germany FS stations considering a C/ criteria of 17 dB. other spots from th
49、e satellite located at the 55 W location will have the benefit of additional satellite antenna discrimination. For the other GE0 satellites, located closer to Germany and therefore with higher elevation angles from Germany to the satellites, it is less likely that interference will occur. All these results were obtained considering no azimuthal pointing difference for the FS antem pointing and the GE0 satellite direction from the FS (all other azimuthal directions should afford further discrimination). The probability of this situation to occur coupled with the probabilit
