CBS/SG-RFC 2001/Doc. 2.2(3) Australian Input Document to ITU-R Working Party 7C. 26 April Summary

Transcription

1 Australian Input Document to ITU-R Working Party 7C CBS/SG-RFC 2001/Doc. 2.2(3) Sharing Analysis in the MHz Frequency Band between S-VISSR Geostationary Meteorological Satellite Earth Stations in the Meteorological Satellite Service and Mobile Satellite Earth Stations in the Mobile Satellite Service invoking ITU Radio Regulations Appendix S7 (WRC-03 Agenda Item 1.31 refers) 1 Summary 26 April 2001 High quality reception by meteorological satellite ground stations of cloud images transmitted in the MHz band by Japan s Geostationary Meteorological Satellite (GMS), China s geostationary meteorological satellite Feng Yun-2 (FY-2) and the United States Geostationary Orbiting Meteorological Satellite (GOES) is critically important to meteorological forecast and warning services in ITU Regions 2 and 3. In ITU Regions 1 & 3 the MHz band is currently allocated to the Meteorological Aids, Meteorological Satellite (space to Earth), Fixed and Mobile except aeronautical mobile services on a co-primary shared basis. The Mobile Satellite Service (MSS) (Earth to space) also shares a co-primary allocation in this band in Region 2. Arising from proposals at WRC 2000 for a worldwide co-primary allocation to MSS (Earth to space) in the MHz band, WRC 2000 Resolution 227 calls for further studies on the feasibility and sharing criteria between the Mobile Satellite and Meteorological Satellite Services. This document examines the feasibility of implementing co-frequency sharing between the MSS and Meteorological Satellite (MetSat) services by determining required coordination distances between Geostationary Meteorological Satellite Earth Stations such as those operated in Australia by the Australian Bureau of Meteorology and Mobile Satellite Earth Stations. These calculations, based on the application of the engineering principles described in ITU-R Recommendations SA , SA , SA and P.526 and importantly ITU Radio Regulations Appendix S7, are presented in spreadsheet form. It concludes that, through the application of Appendix S7, the coordination distances for MSS/MetSat sharing would be in the order of 200 to 500 km rendering sharing difficult. It recommends that Working Party 7C takes the results of this study into account in determining the necessary coordination distances while studying the feasibility of MSS (Earth to space) sharing with GVAR/S-VISSR systems. \\CUMULUS\DATA\SHARED\DEPT\WWW\TEM\sgrfc2001\documents\SVISSRaust.doc 27/04/01 12:42

2 2 Analysis The sharing analysis, described in detail in Appendix A, is presented in three stages in spreadsheet form as Annexes A to C. The three stages are: 2.1 Link budget analyses for GOES GVAR {Geostationary Orbiting Earth Satellite (GOES) Variable} and GMS Stretched Visible and Infra Red Spin Scan Radiometer (S-VISSR) data dissemination uplinks and downlinks with a calculation of tolerable interference power densities. The GOES GVAR analysis, shown in Annex A Sheet 1, correctly derives the figures presented in Table 3 of Recommendation ITU-R SA ( ) while the GMS S-VISSR analysis, shown in Annex A Sheet 2, determines the tolerable interference power densities for the GMS S-VISSR transmissions received by meteorological satellite Earth stations. The analysis shows that these power densities are similar to those given by ITU-R SA Analysis of FY-2 S-VISSR data dissemination produces a similar result 2.2 Calculation of the path loss between a single MSS transmitter mobile Earth station and a GMS S-VISSR receiving Earth station allowing for free space attenuation and diffraction over Earth s surface. This calculation shown as Annex B enables the estimation of the minimum required separation distance assuming free space attenuation and diffraction between a single MSS emitter and the GMS or FY-2 S-VISSR receiving Earth station. The separation distances derived by this analysis are similar to those given by ITU-R Examination in Annex C Sheets 1 and 2 of the effect of anomalous propagation modes, such as tropospheric scatter, ducting, layer reflection/refraction, gaseous absorption, site shielding and hydrometeor scatter by the procedure described in ITU-R Radio Regulations Appendix S7 Methods for the determination of the coordination area around an Earth station in frequency bands between 100 MHz and 105 GHz. The coordination distances between MSS uplink Earth stations, taking into account the likely MSS traffic density, and MetSat GMS or FY-2 S-VISSR downlink Earth stations derived by the application of Appendix S7 are quite large, in the order of 200 km to 500 km. A detailed description and discussion of the above analyses is given in Appendix A. 3 Result of the Analysis The first analysis shows that the tolerance to interference exhibited by GMS and FY-2 S-VISSR MetSat Earth stations is similar to that of GOES GVAR Earth stations modelled in the ITU Recommendation SA-1160 in that reception by both these types of Earth station can be disrupted by very weak interfering signal levels with power densities of the order of dbw/hz short term and dbw/hz long term. Calculations in the second analysis, based on free space and diffraction losses only, show that such disruptive interfering signal levels could result from the presence of a single interfering MSS Earth station as far away as 50 km from the Bureau of Meteorology MetSat S-VISSR receiving Earth station in Melbourne; a distance similar to those given by ITU-R However the application in the third analysis of Appendix S7 which considers surface ducting, elevated layer reflection and refraction and hydrometeor scatter, taking into account the likely MSS traffic density, to determine the coordination distance between a single MSS transmitter and a S-VISSR MetSat Earth station result in far greater coordination distances ranging, for example, from approximately 180 kilometres for a land based MSS transmitter near Melbourne to potentially over 500 kilometres for a sea based MSS transmitter off the coast of New South Wales near Sydney. 2

3 4 Practical application of sharing between MetSat earth stations and MS/MSS subscribers It is obvious that here is a considerable degree of uncertainty in establishing adequate separation distances for co-frequency sharing while the large coordination distances calculated on the basis on the algorithms in Appendix S7 would render co-frequency sharing difficult to manage. However a combination of the sharing methods involving beacon activated sharing and frequency assignment by location as described in ITU-R Rec. SA.1158 may prove practical. 5 Conclusion Theoretical analysis based on the application of Appendix S7 indicates a requirement for such large coordination distances in the order of 200 km and potentially up to 500 km that sharing between MSS Earth station mobile transmitters and meteorological satellite Earth stations receiving S-VISSR transmissions from geostationary meteorological satellites such as those operated by Japan and China would be difficult to implement in practice. 6 Recommendation Working Party 7C is requested to take the results of this study into account in determining the necessary coordination distances while studying the feasibility of MSS (Earth to space) sharing with GVAR/S-VISSR systems. REFERENCES WRC-97 Resolution 220 and 213 WRC-2000 Resolution 227 ITU-R Recommendation Interference Criteria for Data Dissemination and Direct Readout Systems in the Earth Exploration Satellite and Meteorological Satellite Services using Satellites in the Geostationary Orbit ITU-R Recommendation SA Methodology for determining interference criteria for systems in the Earth Exploration-Satellite and Meteorological Satellite Services ITU-R Recommendation SA Sharing of the MHz band between the Meteorological Satellite Service (space to Earth) and the Mobile Satellite Service (Earth-to space) ITU-R Recommendation P.526 Propagation by Diffraction ITU Radio Regulations Appendix S7 Methods for the determination of the coordination area around an earth station in frequency bands between 100 MHz and 105 GHz (adopted by WRC 2000). ITU-R Recommendation S Reference Earth-Station Radiation Pattern for use in Coordination and Interference Assessment in the Frequency Range from 2 to about 30 GHz ITU-R Recommendation S Technical characteristics of Mobile Satellite Systems in the frequency bands below 3 GHz for use in developing criteria for sharing between the Mobile Satellite Service (MSS) and others services 3

4 Detailed description of the Analyses Appendix A 1 Performance Analysis for GOES GVAR and GMS S-VISSR data dissemination uplinks and downlinks with a calculation of tolerable interference power densities. 1.1 GOES GVAR This involved a check link budget calculation to derive the figures presented in Table 3 of Recommendation ITU-R SA ( ). The spreadsheet is presented as Sheet 1 of Annex A in the form of a combined link budget for the 2.11 MB s GOES GVAR uplink from the main Earth station to the GOES satellite and the corresponding downlink from the GOES satellite to a receiving MetSat Earth station. The formulae used in the spreadsheet are given in the Remarks column. The resulting long term downlink interference criteria of dbw/2.11 MHz ( dbw/hz) and short term downlink interference of dbw/2.11 MHz ( dbw/hz) are identical to those for Data dissemination, High gain antenna in Tables 1 and 3 of Rec. SA GMS S-VISSR This analysis determines the system margin and uplink and downlink interference criteria for the GMS S-VISSR transmission using the methods described in Recommendation ITU-R SA ( ). It enabled determination of the tolerable interference power densities for the GMS S- VISSR transmissions received in Australia by the Australian Bureau of Meteorology. The spreadsheet is presented as Sheet 2 of Annex A in the form of a combined link budget for the 660 kb/s S-VISSR uplink from the main Earth station to the GMS satellite and the corresponding downlink from the GMS satellite to a receiving MetSat Earth station. The formulae used in the spreadsheet are given in the Remarks column. For a MetSat ground station with a 5m diameter antenna as used in the Bureau s satellite Earth station at its Head Office in Melbourne, Victoria the resulting long term downlink interference criterion is dbw/660 khz while the short term downlink interference criterion is dbw/660 khz. For a MetSat ground station with a 3.7m diameter antenna as used in the Bureau s satellite Earth station and Turn Around Ranging Stations (for GMS and FY-2) at Crib Point, Victoria the resulting long term downlink interference criterion is dbw/660 khz while the short term downlink interference criterion is dbw/660 khz. For a MetSat ground station with a 2.4m diameter antenna, as used in the Bureau s satellite Earth stations at the Bureau s Regional Offices in Sydney, Perth and Darwin and currently being installed in Brisbane, the resulting long term downlink interference criterion is dbw/660 khz while the short term downlink interference criterion is dbw/660 khz. A 2.4m diameter antenna is the largest antenna that the Bureau can realistically mount on its Regional Office buildings. When converted to spectral density in dbw/hz for comparison with the GOES analysis in Rec. SA.1160 the long term and short term figures for a Bureau GMS MetSat Earth station with a 2.4m diameter antenna become 216 dbw/hz and dbw/hz respectively. These Earth stations can therefore withstand slightly greater interference spectral density than the GOES Earth station analysed in SA which can withstand long term downlink interference of db/hz and short term downlink interference db/hz. 4

5 S-VISSR ground stations using the 2.4m antenna can tolerate less interference than those using the 3.7m antenna - as would be expected. However because GMS has a higher EIRP than GOES, and uses a smaller bandwidth, the combined uplink and downlink paths to our 2.4m and 3.7m Earth Stations have a greater margin than the GOES example in SA hence exhibit a slightly greater tolerance to interference. An analysis for FY-2 S-VISSR reception produces a similar result. The tolerable interference levels for GMS S-VISSR and GOES GVAR Earth stations are summarised in the following table. Tolerable Interference Levels of Australian MetSat Earth Stations GMS S-VISSR Antennas GOES GVAR Antenna Antenna Diameter (m) Location Long term Interference (dbw/660khz) Short term Interference (dbw/660khz) Long term Interference (dbw/hz) Short term Interference (dbw/hz) Sydney NSW Crib Point VIC Melbourne VIC N.A N.A Calculation of the path loss between a single MSS transmitter mobile Earth station and a MetSat (GMS or FY-2) receiving Earth station allowing for free space attenuation and diffraction over Earth s surface. This analysis presented at Annex B enables the estimation of the minimum required separation distance between a single MSS emitter and either a GMS or FY-2 MetSat receiving Earth station as operated by the Australian Bureau of Meteorology. The analysis is carried out for the case where a single MSS emitter is assumed to be located within a 180 degree horizontal arc 90 degrees either side of the azimuthal bearing of the MetSat receiving antenna (i.e. in front of the antenna). If the elevation angle of the MetSat antenna is 45 degrees then the angle subtended at the MetSat antenna between the MetSat antenna boresight and the MSS terminal would therefore always be between 45 and 90 degrees. Taking into account the reservations expressed about small antennas, with D/lambda < 50 in Note 2, and in Note 4 of Rec. ITU-R S the average off axis gain of the MetSat antenna towards the MSS terminal in front of the antenna could reasonably be considered to be isotropic. This is consistent with the manufacturer s specified off axis gains of the 5

6 2.4m and 3.7m antennas. For angles above approximately 90 degrees from boresight the off axis gains of these MetSat antennas fall linearly to 10 db below isotropic at approximately 120 degrees from boresight. This calculation is based on ITU-R SA.1158 Para 4.1 and ITU-R P.526. The spreadsheet determines total path loss as the sum of free space loss and diffraction loss at 1.7 GHz for a Mobile Satellite Service Earth station transmitter interfering with a MetSat receiving Earth station at three possible elevations (10, 30 and 100m) such as on the roofs of buildings (e.g approximately 100m in Melbourne and 30m in Perth or Sydney) for distances between the MSS transmitter and the MetSat Earth station receiver of 20, 30, 50, 70 and 100 km. The results of this calculation are shown graphically in Figure Figure 1: Path Loss between MSS transmitter and Metsat antenna for various elevations of the Metsat antenna Path Loss (db) Metsat ant el = 10m Metsat ant el = 30m Metsat ant el = 100m Distance between MSS and Metsat antennas (km) The path loss increases with distance and is significantly reduced if the MSS transmitter and/or MetSat receiver are elevated. Once the relationship between path loss and separation distance has been established it is a simple matter, if the EIRP of the MSS transmitter is known, to determine how far away from the MetSat receiving station this transmitter must be located so as not to disrupt MetSat reception. For the purposes of this estimation the average NGSO MSS transmitter EIRP is assumed to be +3 dbwi on the basis that current NGSO MSS handset transmitters operating in the MHz band operate at a power of 2 dbw average / +3dBW peak and those intended for vehicle use operate at transmitter powers of +3 dbw average while the horizon gain of the NGSO MSS transmitter antenna is roughly estimated at 0 dbi. It is also assumed that these transmitters employ Code Division Multiple Access (CDMA) technology so many such NGSO MSS transmitters can transmit concurrently in the same frequency band. The CDMA bit rate is inderstood to be in the same order as that used for MetSat S- VISSR downlinks so nearly all the interference power received from one NGSO MSS transmitter operating on the same frequency as the MetSat receiver would affect S-VISSR reception by that receiver. 6

7 Asuming that a single NGSO MSS uplink Earth station transmitter has a EIRP of +3 dbwi then a path loss of 161 db would be required to reduce the interference to below the long term tolerable level of dbw (in a 660 khz bandwidth) for a MetSat GMS Earth station using a 2.4m diameter antenna such as in Sydney. Reference to the results of this spreadsheet shows that a single NGSO MSS Earth station within the 180 degree arc around MetSat antenna azimuth (i.e in front of the MetSat antenna) would therefore need to be located over 30 km away from the MetSat antenna so as not to disrupt GMS reception in Sydney (S-VISSR antenna elevation 30m) and over 50 km away in Melbourne (S-VISSR antenna elevation 100m). Multiple NGSO MSS transmitters would obviously need to be located at greater distances. Based on ITU-R M the output power of a GSO MSS transmitter may be +10 dbw while the horizon gain of the GSO transmitter antenna is assumed to be 0 dbi. The GSO MSS transmitter EIRP is thus estimated at +10 dbi. The separation distances required to protect MetSat reception from GSO MSS transmitters would be significantly greater. 3 Application of ITU-R Radio Regulations Appendix S7 to MSS/MetSat sharing This involves examination of propagation modes such as tropospheric scatter, ducting, layerreflection/refraction, gaseous absorption, site shielding and hydrometeor scatter as described in ITU-R Radio Regulations Appendix S7 Methods for the determination of the coordination area around an Earth station in frequency bands between 100 MHz and 105 GHz. Appendix S7 describes procedures and system parameters for calculating the coordination area in terms of a distance in all directions around a transmitting or receiving Earth station beyond which the predicted path loss would be expected to exceed a specified value for all but a specified percentage of the time. The coordination area thus determined defines the area in which a more detailed assessment should be made of the exclusion zone within which sharing of frequencies between transmitting and receiving Earth stations is prohibited. It embraces two basic propagation modes: mode (1) great circle propagation and mode (2) hydrometeor scatter propagation. Mode (1) considers diffraction over the earth station s local horizon (referred to as site shielding ), tropospheric scatter, surface ducting, and elevated layer reflection and refraction. Mode (2) considers scattering by volumes of hydrometeors common to transmit and receive antenna beams. The Appendix provides a method of determining the coordination area for both these modes by performing iterative solutions for empirical formulae, calculating the combined propagation losses of the various components of the mechanisms embraced by propagation modes (1) and (2). The analysis is carried out for the case where a single MSS emitter is assumed to be located within a 180 degree horizontal arc 90 degrees either side of the azimuthal bearing of the MetSat receiving antenna (i.e. in front of the antenna). If the elevation angle of the MetSat antenna is 45 degrees then the angle subtended at the MetSat antenna between the MetSat antenna boresight and the MSS terminal would therefore always be between 45 and 90 degrees. Taking into account the reservations expressed about small antennas, with D/lambda < 50 in Note 2, and in Note 4 of Rec. ITU-R S the average off axis gain of the MetSat antenna towards the MSS terminal in front of the antenna could reasonably be considered to be isotropic. This is consistent with the manufacturer s specified off axis gains of the 2.4m and 3.7m antennas. For angles above approximately 90 degrees from boresight the off axis gains of these MetSat antennas fall linearly to 10 db below isotropic at approximately 120 degrees from boresight. 7

8 3.1 Propagation Mode (1) For propagation mode (1) (great circle propagation) the nature of the Earth s surface between the transmitting and receiving stations is taken into account by categorising it as Zone A1: coastal land, Zone A2: non-coastal land, Zone B: cold seas and Zone C: warm seas. The reader is requested to refer to Appendix S7; the equation numbers hereunder are those of the equations in that Appendix. To conduct the analysis these equations were transferred to a spreadsheet using parameters for a MSS Earth station to define the transmitting Earth station while the parameters for a S-VISSR MetSat Earth station define the receiving Earth station. The horizon gain of the MSS transmitting antenna is assumed to be isotropic. The horizon gain of the S-VISSR 2.4m receiving station antenna is also assumed to be isotropic. The analysis was conducted for all the Bureau s S-VISSR MetSat Earth stations. The analysis, presented in the Annex C spreadsheet, determines the coordination distance between a NGSO MSS Earth station and the Bureau s S-VISSR MetSat Earth station in Sydney. First the percentage of time that clear air anomalous conditions exist near Sydney (Be) was calculated at 15.4% (equation 7) from the latitude of Sydney (34 degrees). The sea level surface refractive index of 354 (equation 11) and minimum coordination distance at 107 km were then calculated (equation 12). The minimum required loss was then calculated as 152 db {MSS EIRP (+3 dbwi) minus circular to linear polarisation loss (3dB) minus clutter loss (assumed 0 db) minus horizon gain of 2.4m MetSat antenna (0 dbi) minus the interference power for p=0.025% (-152dBW for GMS S-VISSR MetSat Earth station}. The value of p (=0.025%), the percentage of the time for which the specified level of interfernce power shall not be exceeded, is extracted from ITU-R SA The interference power of 152 dbw is derived for a 2.4m antenna in Annex A Sheet 2 of this document, using the same methodology as ITU-R SA Referring to Annex I of Appendix 7, site shielding parameters were calculated using equations I-2A through I-3. Because the frequency range ( GHz +/- 3MHz) containing the S-VISSR transmission is covered by Annex I paragraph 3 of Appendix S7 the remainder of the calculation followed the method prescribed by this paragraph. Equations I-11c through I-14 were therefore evaluated to allow for specific attenuation due to gaseous absorption, equations I-15 through I-17 to allow for the ducting model and I-19 through I-21 to allow for the tropospheric scatter model. In implementing the iterative process specified by Appendix 7 equations I-22 through I-33 were evaluated during each iteration commencing at the minimum distance, then for successively increasing distances until the inequalities of equation I-10a were satisfied. The example of this iteration process is given in the spreadsheet Annex C Sheets 1 and 2. Commencing at the minimum coordination distance of 106 km and incrementing this distance by 1 km for each iteration, the required inequalities are not satisfied until a coordination distance of 232 km is reached. Assuming the MSS emitter is on board a ship at sea the coordination distance increases to approximately 500 km depending on how far inland the MetSat receiving antenna is located; in this case approximately 10 km. Similar calculations for NGSO and GSO MSS/MetSat coordination distances for the Bureau s MetSat Earth stations in Melbourne and at Crib Point gave the results in the following table: 8

9 Appendix S7 MSS/MetSat Coordination Distances NGSO MSS Coordination Distance (km) GSO MSS Coordination Distance (km) Melbourne Land Crib Point land Sydney land Sydney at sea The reason for the significant increase in predicted separation distances beyond those predicted by ITU-R SA.1158 is that application of Appendix S7 takes into account the stochastic nature of propagation supported by ducting and tropospheric scatter resulting in much lower predicted path losses as shown in Figure Figure 2: Path Loss, Sa and Appendix S7 (p=0.025%) SA db Ap S7 duct Ap S7 tropo distance (km) MSS Traffic intensity and cumulative effect of multiple subscribers For purpose of the analysis it has been assumed that the total MSS traffic intensity may approximate 8000 two to five minute calls per day and these calls involve MSS subscribers in those parts of Australia covered by major highways and generally out of range of cellular mobile telephone coverage around capital cities. Australia s major highways are mostly concentrated near the east coast of Australia over an area roughly one million square kilometres, with major highways elsewhere on the mainland occupying a similar area. The average call rate is therefore 8000 two to five minute calls per day with each call involving one MSS subscriber in an area 2 million/8000 = 250 square kilometres or 9

10 15.8 kilometres square. Assuming a coordination area around a city based MetSat Earth station of radius 150 km, on average there would be approximately 60 MSS subscribers operating for 2 to 5 minutes per day (a total call busy time of 2 to 5 subscriber hours) within an annular zone of radius 150 kilometres and incremental radius 15.8 km (covering an area of approximately 15,000 square kilometres) surrounding the MetSat Earth station. During the busy periods of the day between 9 and 11 a.m. and 3 to 6 p.m. and considering that MSS subscriber traffic will be denser on highways near the capital cities the number of active subscribers surrounding the coordination area may easily be up to 3 times greater. It would therefore not be unrealistic for a worst case analysis to assume a MSS traffic intensity during the busy hours equivalent to a single MSS subscriber transmitting continuously from a location some 150 kilometres from the city based MetSat Earth station. It can be shown by numerical integration that signals propagated from all other MSS subscribers outside this area would add some 5 db to the interference level. The analysis has therefore been based on the worst case assumption that at any given time during the busy periods of the day a single MSS subscriber is transmitting continuously at the boundary of the MSS/MetSat coordination area Effect of Horizon Shielding To minimise the influence of man made noise the Bureau s MetSat antennas are mounted on the roofs of its Regional Office buildings. Each MetSat antenna has a zero or slightly negative local horizon wherever the antenna has a clear view of the physical horizon. There would be therefore little horizon shielding as defined by Appendix S7 against MSS interference except in directions where the path is obstructed by city buildings. For example the Bureau s MetSat antenna in Perth has an unobstructed view of the horizon. On the other hand in Sydney the horizon is approximately 30% obscured by buildings taller than the Bureau s MetSat antenna location. The MetSat antenna in Sydney would therefore enjoy some protection by buildings obstructing the interference propagation path, reducing the probability of a specific MSS emitter interfering with GMS reception. In practice a detailed coordination contour would need to be constructed in five degree increments around the MetSat Earth station to allow for the obstruction of the distant horizon by tall city buildings or for MetSats at lower elevation angles such as 30 degrees for Feng Yun-2 at Crib Point. 3.2 Propagation Mode (2) (hydrometeor scatter) Propagation Mode (2) - hydrometeor scatter, covered by Annex II of Appendix S7 was found to display too great an attenuation to support significant MSS to MetSat interference. Hydrometeor scatter therefore makes no significant contribution to the interference by MSS transmitters to MetSat reception. 3.3 Remark on the application of Appendix S7 The coordination distances for MSS MetSat sharing determined using the methods prescribed by Appendix S7 are much larger than the required separation distances estimated by free space and diffraction considerations. However the methods prescribed by Appendix S7 are necessarily complex, reflecting the probabilistic nature of the physical phenomena determining the propagation characteristics of Earth s atmosphere. This tends to add a degree of uncertainty to the coordination process. 10

11 3.4 Implementation of sharing between MetSat earth stations and MS/MSS subscribers Sharing techniques for MSS and MetSat Earth stations in the MHz frequency band are described in Annex 3 of ITU Recommendation SA Examination of published coverage maps by Mobile (such as cellular mobile phone) Service providers show coverage around Australian State capital cities generally along highways but with irregular boundaries outside which the Mobile Satellite Service could be expected to provide service. Depending on how the cellular phone coverage is arranged and physical characteristics such as the nature of the terrain along the path between any particular mobile MS/MSS handset and the MetSat Earth station or the nature of the atmosphere perhaps favouring ducting or tropospheric scatter propagation, situations may well arise where the MS/MSS subscriber out of range of his or her local MS cell may be forced to revert to MSS operation while the propagation path to the MetSat Earth station is open. Such a circumstance would be difficult to eliminate in practice and therefore could have a deleterious effect on MetSat reception. It could possibly be averted by beacon actuated protection of the MetSat station as described by ITU-R SA An alternative method of sharing would require each MSS terminal to be equipped with a position determining capability and provide this information to the MSS network management system on a signalling channel which would not interfere with MetSat downlinks. The NMS would maintain a data base of locations wherefrom the MSS would not be permitted to transmit and could consult this data base before permission to transmit was given. This method is referred to by ITU-R Rec. SA as frequency assignment by location. A combination of beacon activated sharing and frequency assignment by location may prove practical. 11

12 ANNEX A Performance Analysis for GOES G-VAR Data Dissemination Uplink and sheet 1 Downlinks with calculation of Tolerable Interference Power Densities Ref ITU-R SA , SA1158-2, SA and SA Downlink ES Rx antenna gain = 39.5 dbi Remarks Modulation BPSK Frequency MHz 10logk db(joule/k) Uplink uplink EIRP dbw 72.1 uplink loss db Uplink loss = = db uplink G/T db/k uplink C/No db/hz 91.5 (C/No = Pt Lfs + G/T -10logk) Downlink Downlink EIRP dbw 23.8 Downlink loss db Downlink loss = db Downlink G/T db/k 15.2 Downlink C/No db/hz 77.5 (C/No = Pt Lfs + G/T -10logk) Composite C/No db/hz 77.3 (Comp C/No = -10log(10^-C/No,up + 10^C/No,dn) data rate (db Hz) = 10 log 63.2 data rate Data rate 2.11 Mbit/s db Hz 63.2 C/N for ber of 1 x 10^-6 = 10.8 demodulation loss = 1.9 Required C/No db/hz 75.9 Req. C/N = 12.7 Margin db 1.4 Remarks uplink receive antenna gain dbi 9.5 uplink noise density dbw/hz T deg K = 500 uplink interference criterion Io1 = p*kt1[1 + (C/No,up)/(C/No,dn)](M^q-1) long term dbw/hz q = short term dbw/hz q = 1 long term per 2.11 MHz p = 0.5 short term per 2.11MHz Downlink receive antenna gain dbi 39.5 Downlink noise density dbw/hz T deg K = 269 Downlink interference criterion Io2 = (1-p)*kT2[1 + (C/No,dn)/(C/No,up)](M^q-1) long term dbw/hz q = short term dbw/hz q = 1 long term per 2.11 MHz p = 0.5 short term per 2.11MHz long term dbw/khz short term dbw/khz

13 ANNEX A Performance Analysis for GMS S-VISSR Data Dissemination Uplink and Downlinks sheet 2 with calculation of Tolerable Interference Power Densities Ref ITU-R SA , SA1158-2, SA and SA Earth Station Receive antenna diameters: 2.4m 3.7m 5m Remarks Modulation BPSK BPSK BPSK Frequency logk db(joule/k) MHz MHz MHz Uplink uplink EIRP dbw Lfs = logf+20logd = uplink loss db Tx ant pointing loss (Txpl) = 0.25 uplink G/T db/k Rx ant pointing loss (Rxpl) = 1 uplink C/No db/hz Uplink loss = Lfs + Txpl +Rxpl+ AFl = (C/No = Pt - Lfs + G/T -10logk) f= d= Atmospheric & Faraday losses = 0.3 downlink EIRP dbw Downlink downlink loss db Lfs = logf+20logd = downlink G/T db/k Tx ant pointing loss (Txpl) = 1 downlink C/No db/hz Rx ant pointing loss (Rxpl) = 0.25 Downlink loss = Lfs+ Txpl +Rxpl +Afl = (C/No = Pt - Lfs + G/T -10logk) f = d = Atmospheric & Faraday losses = 0.3 Composite C/No db/hz (Comp C/No = -10log(10^-C/No,up + 10^C/No,dn) data rate (db) = 10 log data rate = 58.2 Data rate 660 kbit/s C/N for ber of 1 x 10^-6 = 10.8 demodulation loss = 1.9 Required C/No db/hz Req. C/N = 12.7 Margin uplink receive antenna gain dbi uplink noise density dbw/hz T (deg K) = 10^(( G - G/T)/10) 6607 (where G = 16.2 dbi, G/T = -22) uplink interference criterion Io1 = p*kt1[1 + (C/No,up)/(C/No,dn)](M^q-1) long term dbw/hz q = short term dbw/hz q = 1 long term per 660 khz p = 0.5 short term per 660 khz downlink receive antenna gain dbi downlink noise density dbw/hz T deg K = 150 downlink interference criterion Io2 = (1-p)*kT2[1 + (C/No,dn)/(C/No,up)](M^q-1) long term dbw/hz q = short term dbw/hz q = 1 long term per 660 khz p = 0.5 short term per khz long term dbw/khz short term dbw/khz long term for comparison with SA dbw/2.11mhz short term dbw/2.11mhz

14 ANNEX B Calculation of Path Loss between isotropic MSS transmitter and isotropic Metsat Receiver antennas allowing for free space loss and diffraction over Earth's surface References: ITU-R Recommendations SA , P.526 Formulae used: Lt = Ls + Ld Where: Lt - total path loss between isotropic antennas; Ld = diffraction loss (db), Ls = free space loss (db) = 20 log (42df) where f = frequency (MHz), d = path length (km). In calculating diffraction loss: Distance Term F(X) = logX -17.6X where X = 2.2B f^1/3 a^-2/3 d; B (polarization parameter) =1; a = equivalent Earth radius = 8500 km. Antenna "height gain" terms G(Y1) and G(Y2) are given by G(Y) = 20 log (Y Y^3) where Y = 9.6 x 10^-3 B f^2/3 a^-1/3 h; h1 = height above Earth's surface of transmitter (MSS) antenna, h2 = height above Earth's surface of receiver (Metsat) antenna. D h1 h2 X F(X) Y1 Y2 G(Y1) G(Y2) Ld Ls Lt Km m m db db db db db db

15 ANNEX C sheet 1 Application of ITU Radio Regulations Appendix S7 to MetSat/NGSO MSS sharing Propagation mode (1) Great Circle Ducting and Tropospheric Scatter, Iterative Calculations SYDNEY Propagation from a single MSS transmitter on land Iterative Calculations Iteration No. 125 MSS EIRP (dbwi) = 3 Metsat ant gain = 0 clutter = 0 Pol los = 3 ES latitude (Lat) = 34 Frequency (GHz) = e = Latr = 32.2 power = 0.96 No = 354 p% = Anaprop time (%) Be = 15.4 Dx (km) = 87.7 Min coord dist (km) = 107 Tolerable interference power Metsat Earth station (2.4m antenna) at LNC input in Sydney (dbw) = -152 Minimum required loss between MSS emitter and LNC input for p% of the time (db) is: MSS EIRP clutter - polarization loss + Metsat ant gain - tolerable interference power = Lb(p) (db) = 152 MetSat ES Horizon dist Horizon angle Dh = 5 Eh = 0 From Appendix S7 ANNEX I. Site shielding due to horizon distance = Ad = 0.0 (I-1) Total site shielding due to horizon distance and horizon elevation angle = Ah for Eh >=0 Ah = 0.0 (I-2a) For -0.5=<Eh <0 Ah = 0.0 (I-2b) For Eh <-0.5 Ah = -0.9 (I-2c) 1st interim Ah = 0.0 2nd interim Ah = 0.0 Ah >-10 limit Ah limit = Final Ah = 0.0 (I-3) Dmin (km) = 107 (I-10c) Incremental distance S (km) = 1 Correction constant Z(f) DB/km Specific attenuation through gas absorption Gamma0 = (I-11a) Gammawt (rho =3) 5.52E-05 (I-13a) Rho = 3 Gammawdl (rho=7.5) 1.58E-04 (I-13b) 7.5 Gammawds (rho =10) 2.26E-04 (I-13c) 10 Gammad = (I-14) Ducting - Attenuation reduction due to direct coupling into sea ducts: Ac= (I-15) Dc (km)= 7 Min loss A1 = (I-16) L3(p) (db)= 26.6 (I-17a) Tropospheric Scatter Frequency dependent loss L(f) = 5.7 (I-19) Non distance dependent loss (A2) L4(p) (db) = 35.4 (I-21a) Iterative Calculations Iteration No. 125 Current distance Di = 231 (I-22) current aggregate land dist. Zones(A1+A2) wi. current path Dt 231 longest continuous inland dist. Zone(A2) wi. current path Dlm 231 longest continuous land dist. Zones(A1+A2) wi. current path Dtm 231 Gas absorption specific attenuation Gammag (I-23) Tau (I-24) Mu with Mu1 =< 1 so Mu (I-25) Sigma with Sigma >= -3.4 so Sigma (I-26) Mu with Mu2 =< 1 so Mu (I-27) Mu (I-28a) Path dependent incidence of ducting Beta (I-29) Related parameter TAU (I-30) Cor. Factor D2i db D2i Distance dependent part of ducting loss L5(p) (db) = 26.5 (I-32) Distance dependent part of tropospheric scatter L6(p) (db) = 74.2 (I-33) Check L5(p) - L3(p) = -0.1 (I-10a) L6(p) - L4(p) = 38.8 (I-10a) Result L5<L3 and L6>=L4 So REPEAT ITERATION 15

16 ANNEX C sheet 2 Application of ITU Radio Regulations Appendix S7 to MetSat/NGSO MSS sharing Propagation mode (1) Great Circle Ducting and Tropospheric Scatter, Iterative Calculations SYDNEY Propagation from a single MSS transmitter on land Iterative Calculations Iteration No. 126 MSS EIRP (dbwi) = 3 Metsat ant gain = 0 clutter = 0 Pol los = 3 ES latitude (Lat) = 34 Frequency (GHz) = e = Latr = 32.2 power = 0.96 No = 354 p% = Anaprop time (%) Be = 15.4 Dx (km) = 87.7 Min coord dist (km) = 107 Tolerable interference power Metsat Earth station (2.4m antenna) at LNC input in Sydney (dbw) = -152 Minimum required loss between MSS emitter and LNC input for p% of the time (db) is: MSS EIRP - clutter - polarization loss + Metsat ant gain - tolerable interference power = Lb(p) (db) = 152 MetSat ES Horizon dist Horizon angle Dh = 5 Eh = 0 From Appendix S7 ANNEX I Site shielding due to horizon distance = Ad = 0.0 (I-1) Total site shielding due to horizon distance and horizon elevation angle = Ah for Eh >=0 Ah = 0.0 (I-2a) For -0.5=<Eh <0 Ah = 0.0 (I-2b) For Eh <-0.5 Ah = -0.9 (I-2c) 1st interim Ah = 0.0 2nd interim Ah = 0.0 Ah >-10 limit Ah limit = Final Ah = 0.0 (I-3) Dmin (km) = 107 (I-10c) Incremental distance S (km) = 1 Correction constant Z(f) DB/km Specific attenuation through gas absorption Gamma0 = (I-11a) Gammawt (rho =3) 5.52E-05 (I-13a) Rho = 3 Gammawdl (rho=7.5) 1.58E-04 (I-13b) 7.5 Gammawds (rho =10) 2.26E-04 (I-13c) 10 Gammad = (I-14) Ducting - Attenuation reduction due to direct coupling into sea ducts: Ac= (I-15) Dc (km)= 7 Min loss A1 = (I-16) L3(p) (db)= 26.6 (I-17a) Tropospheric Scatter Frequency dependent loss L(f) = 5.7 (I-19) Non distance dependent loss (A2) L4(p) (db) = 35.4 (I-21a) Iterative Calculations Iteration No. 126 Current distance Di = 232 (I-22) current aggregate land dist. Zones(A1+A2) wi. current path Dt 232 longest continuous inland dist. Zone(A2) wi. current path Dlm 232 longest continuous land dist. Zones(A1+A2) wi. current path Dtm 232 Gas absorption specific attenuation Gammag (I-23) Tau (I-24) Mu with Mu1 =< 1 so Mu (I-25) Sigma with Sigma >= -3.4 so Sigma (I-26) Mu with Mu2 =< 1 so Mu (I-27) Mu (I-28a) Path dependent incidence of ducting Beta (I-29) Related parameter TAU (I-30) Cor. Factor D2i db D2i Distance dependent part of ducting loss L5(p) (db) = 26.7 (I-32) Distance dependent part of tropospheric scatter L6(p) (db) = 74.4 (I-33) Check L5(p) - L3(p) = 0.1 (I-10a) L6(p) - L4(p) = 39.0 (I-10a) Result L5>=L3 and L6>=L4 So FINISH 16