RECOMMENDATION ITU-R S Coordination identification between geostationary-satellite orbit fixed-satellite service networks

Transcription

1 Rec. ITU-R S RECOMMENDATION ITU-R S.1524 Coordinaion idenificaion beween geosaionary-saellie orbi fixed-saellie service neworks (2001) The ITU Radiocommunicaion Assembly, considering a) ha he Plenipoeniary Conference (Minneapolis, 1998) agreed, hrough Resoluion 86, on he need for improved coordinaion and noificaion of saellie neworks; b) ha here is a need o accelerae he idenificaion of geosaionary-saellie orbi fixed-saellie service (GSO FSS) neworks wih which coordinaion is required; c) ha simple mehods are needed for idenifying he necessary co-frequency GSO FSS neworks wih which coordinaion mus ake place and which can be used in fulfilmen of he objecives of Resoluion 86; d) ha ypical nework characerisics of 6/4 GHz, 13-14/11-12 GHz and 30/20 GHz GSO FSS neworks are well known; e) ha in many pars of he GSO co-frequency FSS neworks in bands idenified in considering d) above are closely spaced wih overlapping beams; f) ha he operaors of such neworks have exensive experience in coordinaing saellie sysems wih oher co-frequency saellie sysems; g) ha where applicable, he off-axis equivalen isoropically radiaed power (e.i.r.p.) densiy recommended maximum levels on GSO FSS earh saions oward an adjacen GSO FSS nework and power flux-densiy limis on GSO FSS space saions a he surface of he Earh are among he mos imporan echnical parameers used in defining orbial separaion; h) ha a coordinaion arc can be defined around a given nework such ha inerference beween ha nework and neworks ouside ha arc may ypically be considered negligible compared o he inerference from neworks wihin ha arc; j) ha nework parameers developed o accommodae neworks wihin he coordinaion arc would likely help o accommodae neworks a greaer orbial spacing; k) ha he coordinaion arc, by iself, may no be sufficien in some cases o idenify all neworks which migh cause inerference o or receive inerference from a new nework; l) ha he World Radiocommunicaion Conference (Isanbul, 2000) adoped Resoluion 55 (WRC-2000) o bring ino effec emporary procedures for improving saellie nework coordinaion, including modificaions o Aricles 9, 11 and Table 5-1 of Appendix 5 of he Radio Regulaions (RR),

2 2 Rec. ITU-R S.1524 recommends 1 ha deerminaion of he need for coordinaion beween GSO FSS neworks should be based on coordinaion arcs of ± 10, in he bands MHz, MHz (Region 1) and MHz, ± 9 in he bands GHz, GHz, GHz (Region 2), GHz (Region 3), GHz (Regions 1 and 3), GHz (Region 2), and GHz, and ± 8 in he bands GHz and GHz abou he nominal orbial posiions of hose neworks; 2 ha, alhough he full RR Appendix 4 daa mus sill be provided, he informaion in Annex 1 is sufficien, and should be used, for deermining wheher he hreshold coordinaion arc condiions defined in recommends 1 are exceeded for a co-frequency GSO FSS nework; 3 ha an adminisraion, on is own iniiaive or wih he assisance of he Radiocommunicaion Bureau (BR) in applicaion of No and oher relevan provisions of he RR (e.q. No. 13.1), may reques ha a co-frequency GSO FSS saellie nework ouside he coordinaion arc be included in coordinaion when he adminisraion can demonsrae by analysis ha he increase in he sysem noise due o he proposed nework exceeds 6%; 4 ha he adminisraion filing he reques for coordinaion, on is own iniiaive or wih he assisance of he BR in applicaion of No and oher relevan provisions of he RR (e.q. No. 13.1), may reques ha a co-frequency GSO FSS saellie nework wihin he coordinaion arc be excluded from he coordinaion when he filing adminisraion can demonsrae by analysis ha he increase in sysem noise o he nework, wihin he coordinaion arc due o he proposed nework, is less han 6%. This is o be confirmed by he BR which will inform he concerned adminisraions. NOTE 1 In order o implemen recommends 3 and 4, he relevan RR Appendix 4 daa should be used. NOTE 2 The coordinaion arc should apply o coordinaion only beween saellie neworks in he FSS using he GSO and operaing in he same direcion of ransmission. NOTE 3 The bases for he values in recommends 1 are given in Annex 2. NOTE 4 In oher FSS bands han hose lised in recommends 1 and hose covered by RR Appendix 30B, T / T of 6% would coninue o apply. ANNEX 1 Informaion required for idenificaion of adminisraions and saellie neworks based on GSO coordinaion arcs A.1.a: Ideniy of saellie nework A.1.f: Counry symbol of he noifying adminisraion A.3: Operaing adminisraion or agency A.4.a.1: Nominal geographic longiude of he space saion on he GSO C.2.a: Assigned frequency C.3.a: Assigned frequency band. NOTE 1 All informaion required for idenificaion of adminisraions and saellie neworks based on GSO coordinaion arcs is also required in RR Appendix 4 for noificaion or coordinaion of a GSO nework. Accordingly he RR Appendix 4 iem numbers are provided.

3 Rec. ITU-R S ANNEX 2 Coordinaion idenificaion beween GSO FSS neworks 1 Inroducion This Annex deals wih he appropriae coordinaion arc which may be adoped for idenifying he need for coordinaion beween GSO FSS neworks in he bands 6/4 GHz, 13-14/11-12 GHz, and 30/20 GHz. The objecive of he calculaion is o define an orbial separaion angle, α, beyond which he increase in noise emperaure of he nework subjec o inerference will no exceed 6%. Coordinaion would be required when a GSO nework is wihin ± α from he proposed nework. The approach used is o examine he excess inerference in ypical FSS sysems caused by oher ypical FSS sysems a varying angular separaions, and assessing he resulan risk creaed by no coordinaing he wo neworks a he separaion value. 2 Resuls of sudies 2.1 Mehodology and assumpions The mehodology used o calculae he separaion angle beween wo GSO FSS neworks is described below: Firs, he oal carrier o noise + inerference raio (C/(N + I )) is calculaed for he inerfered wih sysem. The aggregae inerference from oher GSO neworks ino he waned sysem is se a 20% of he oal sysem noise. The single-enry inerference from one GSO nework is 6% of he oal sysem noise and allocaed equally beween he uplink and he downlink direcion. Generally, he inerference in a link is dominaed by he conribuion of inerference from one direcion raher han he oher. Thus, his assumpion will give a larger separaion angle han ha in a case of reaing each link direcion separaely wih he full 6% allowable inerference allocaed for each direcion. The anenna paern of he receiving earh saion is assumed o comply wih log ϕ. For he uplink direcion, he inerfering ransmiing earh saion is assumed o be locaed a he waned saellie maximum gain direcion and he pah losses are assumed o be he same for boh he waned and he inerfering direcion. The required separaion angle will hen be deermined from he off-axis e.i.r.p. densiy radiaion paern of he inerfering ransmiing earh saion. For he downlink direcion, he inerfering receiving earh saion is assumed o be collocaed wih he waned earh saion. The required separaion angle will hen be deermined from he inerfering saellie e.i.r.p. densiy and he receiving anenna paern of he inerfered earh saion.

4 4 Rec. ITU-R S Sysem parameers The parameers of he GSO neworks used in his sudy are aken from he ransparen (benpipe) GSO link budge daabases for he 13-14/11-12 GHz and 30/20 GHz bands. The fac ha hese carriers were given for he mos sensiive GSO FSS links has been noed, however his daabase represens a suiable reference of GSO carriers for his purpose. I is also noed ha for a ypical GSO link budge, he separaion angles would be smaller due o he high power of he GSO carriers. Table 1 shows he assumed off-axis e.i.r.p. densiy used in his sudy. The ransmiing earh saion off-axis e.i.r.p. densiy values are aken from Recommendaion ITU-R S.524 for boh he 13-14/11-12 GHz and 30/20 GHz bands (in he case of 30/20 GHz band, Recommendaion ITU-R S.524 conains off-axis e.i.r.p. densiy values only for he frequency range GHz). TABLE 1 e.i.r.p. and anenna paern of GSO FSS neworks Frequency band (GHz) 13-14/ Inerfering Tx earh saion off-axis e.i.r.p. densiy (db(w/40 khz)) Inerfering Tx saellie e.i.r.p. densiy (db(w/hz)) Waned earh saion anenna paern log ϕ for 2.5 ϕ log ϕ 30/ log ϕ for 2.0 ϕ log ϕ 2.3 Deerminaion of single-enry carrier o inerference (C /I ) due o inerference from anoher GSO nework This secion describes he calculaion required o deermine he allowable inerference from oher GSO neworks ino an inerfered-wih GSO nework from he parameers provided in hese daabases. Throughou his Annex, raios expressed in lower case leers are used o denoe power raios and upper case leers are used when he power raios are expressed in db. The uplink is designaed by he subscrip and he downlink by he subscrip. The oal power from boh uplink and downlink is designaed by he subscrip. The oal carrier-o-sysem noise raio of he waned nework which is comprised of hermal noise, inernal noise and inerference due o oher GSO neworks and erresrial sysems is deermined as follows: c i + n c = n + i c inernal + i c erresrial c + i GSO (1) where: c/(i + n) : (c/n) : oal carrier-o-sysem noise raio (uplink and downlink direcion) carrier-o-hermal noise raio from boh uplink and downlink direcion

5 Rec. ITU-R S (c/i inernal ) : (c/i erresrial ) : (c/i GSO ) : carrier-o-inernal inerference raio from boh uplink and downlink direcion carrier-o-erresrial inerference raio from boh uplink and downlink direcion carrier-o inerference raio due o all oher GSO neworks from boh uplink and downlink direcion. Assuming ha he aggregae inerference due o all oher GSO neworks and he single-enry inerference from one GSO nework (boh uplink and downlink) are 20% and 6% of he oal sysem noise, respecively, we have: c c c c = + + isei_gso n i inernal ierresrial (2) where: (c/i SEI_GSO ) : carrier-o-inerference raio due o one inerfering GSO nework. The oal inerference due o anoher GSO nework is assumed o be allocaed equally o boh uplink and downlink direcion. Thus, he C /I SEI_GSO in he uplink and downlink will be 3 db higher han he oal C /I SEI_GSO which is deermined from equaion (2). C C = C = ISEI_GSO I SEI_GSO ISEI_GSO + 3 db (3) 2.4 Deerminaion of he required uplink separaion angle The separaion angles for boh uplink and downlink are hen calculaed from he C /I SEI-GSO aking ino accoun he bandwidh difference beween he waned and inerfering nework. 3 Resuls of sudies using maximum and minimum e.i.r.p. daa The excess inerference margins were calculaed using INTELSAT IICM parameers. The values used for he maximum inerfering parameers are given in Table 2 and for he minimum receive parameers are given in Table 3, respecively. These parameers are considered ypical of many sysems in he FSS. In order o simplify he differen combinaions and ypes of carriers used in he INTELSAT sysem, all carriers were caegorized ino one of four disinc ypes, namely: narrow-band carriers, wideband carriers, analogue frequency division muliplex/frequency modulaion (FDM/FM) or companded frequency division muliplex (CFDM)/FM carriers, FM/TV (slowly swep) carriers. The summary of he carrier parameers used in his sudy is given in Table 3.

6 6 Rec. ITU-R S.1524 TABLE 2 Uplink and downlink limis for use in calculaing inerference margins in Tables 4 and 5 Frequency band (GHz) Non-FM/TV uplink power densiy (db(w/hz)) FM/TV uplink power (dbw) Non-FM/TV downlink e.i.r.p. densiy (db(w/hz)) FM/TV downlink e.i.r.p. (dbw) 6/ / Using he limis defined in 2, Table 4 gives he excess inerference margin for he differen ypes of carriers a various orbial separaions for he 6/4 GHz band, and Table 5 gives he excess inerference margin for he differen ypes of carriers a various orbial separaions for he 13-14/11-12 GHz band. I should be noed ha he inerference margin compued from FM/TV ino narrow-band carriers assumes ha he FM/TV carriers are modulaed a all imes wih live video or es paerns in addiion o he energy dispersal signal so ha hey can be reaed as noise-like inerference wih a maximum specral densiy of 63 dbc/hz. I is assumed ha he inerfering beam is copolarized and operaes co-frequency wih he waned nework beam. A 1 db of opocenric advanage is used. In he derivaion of he wors-case inerference margin given in Tables 4 and 5, he following assumpions were made. Based on hese assumpions, improvemen facors are also idenified: For deermining he uplink inerference margin, i is assumed ha he inerfering earh saion is locaed a he beam peak of he waned nework receive beam. For deermining he downlink inerference margin, i is assumed ha he waned receive earh saion is locaed a he beam peak of he inerfering ransmi beam. This represens a wors-case condiion and, on average, he inerference margin could be improved by 2 db. The carriers ransmied or received a he earh saions as assumed in his sudy are wors-case carriers. In general, such wors-case siuaions do no arise due o he compaibiliy requiremens wih he closer adjacen saellie neworks, and he fac ha he wors-case carriers of he inerfering nework are no co-frequency wih he mos sensiive carriers of he waned neworks. Based on hese assumpions, he inerference margin could be improved by up o 3 db. The earh saions side-lobe performance assumed in his sudy follow exacly he log ϕ paern of some ITU-R Recommendaions. On average, he inerference margin could be improved by 1 db due o improved performance in acual side lobe. Taking ino consideraion he facors described above, he negaive inerference margins of up o 6 db wih respec o he T / T crieria could be considered accepable. Furhermore, due o he fac ha he measures o be adoped by he proposed saellie sysem in order o proec inervening adjacen saellies will considerably reduce he poenial o cause inerference ino saellies locaed farher away, some prior safey facor may be assumed.

7 Rec. ITU-R S Summary of resuls From he resuls, i follows ha an angular separaion of ± 9 for he 13-14/11-12 GHz band and ± 8 for he 30/20 GHz band will ensure ha he T / T of 80% of he GSO FSS neworks sudied will no exceed he value of 6%. These values can be used as a rigger for he coordinaion of GSO neworks sharing he same frequency band. The choice of an appropriae value o selec depends upon he perceived likelihood ha he presence of inervening successfully coordinaed neworks would assure ha inerference is no likely. In he hree bands in quesion, he nominal separaions in mos counries range from 2-4 in he 6/4 GHz band, and 2 in he 13-14/11-12 GHz and he 30/20 GHz bands. Thus, i is o be expeced ha he number of inervening neworks would be higher a 6/4 GHz band han in he oher wo bands. Thus, coordinaion arcs of ± 10, ± 9 and ± 8 are indicaed. The maximum permissible uplink power densiy and uplink power level assumes a ransmi earh saion anenna side-lobe envelope of log ϕ. TABLE 3 Summary of INTELSAT minimum parameers used in he calculaion of inerference margins in Tables 4 and 5 Space saion Carrier ype Uplink frequency (GHz) Downlink frequency (GHz) Uplink e.i.r.p. (dbw) Downlink e.i.r.p. (dbw) C / N Occupied bandwidh (MHz) Rx earh saion gain (dbi) VII/VIIA Analogue VIII VII/VIIA IX VII VII Narrow-band Narrow-band VII/VIIA FM/TV VII/VIIA FM/TV VIII Analogue VIII Analogue Narrow-band VIII IX VII Narrow-band IX FM/TV VII FM/TV

8 8 Rec. ITU-R S.1524 Trigger angle (degrees) TABLE 4 Wors-case inerference margin a 6/4 GHz band Inerfering carrier Non-FM/TV FM/TV (1) Waned carriers Inerference margin Inerference margin 6 Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV 1.1 (1) FM/TV modulaed by video (noise-like wih 63 dbc/hz).

9 Rec. ITU-R S Trigger angle (degrees) TABLE 5 Wors-case inerference margin a 13-14/11-12 GHz band Inerfering carrier Non-FM/TV FM/TV (1) Waned carriers Inerference margin Inerference margin 6 Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV Analogue Narrow-band FM/TV 15 Analogue Narrow-band FM/TV (1) FM/TV modulaed by video (noise-like wih 63 dbc/hz).