CA2088052A1 - Satellite mobile communication system for rural service areas - Google Patents
Satellite mobile communication system for rural service areasInfo
- Publication number
- CA2088052A1 CA2088052A1 CA002088052A CA2088052A CA2088052A1 CA 2088052 A1 CA2088052 A1 CA 2088052A1 CA 002088052 A CA002088052 A CA 002088052A CA 2088052 A CA2088052 A CA 2088052A CA 2088052 A1 CA2088052 A1 CA 2088052A1
- Authority
- CA
- Canada
- Prior art keywords
- satellite
- remote
- converter
- cell site
- mtso
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
-
- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B7/00—Radio transmission systems, i.e. using radiation field
- H04B7/14—Relay systems
- H04B7/15—Active relay systems
- H04B7/185—Space-based or airborne stations; Stations for satellite systems
- H04B7/1853—Satellite systems for providing telephony service to a mobile station, i.e. mobile satellite service
- H04B7/18558—Arrangements for managing communications, i.e. for setting up, maintaining or releasing a call between stations
Abstract
A mobile communications system uses a communications satellite (130) and a Mobile Telephone Switching Office (MTSO) (150) and communicates with mobile units (101, 102) via the satellite (130). A
cell site (140) has a co-located cell site converter (145) which converts satellite signals to signals for the MTSO and vice-versa. Remote converter sites (110-113) communicate with the satellite (130) and with the mobile units (101, 102) in given geographical areas. A single satellite link is sufficient for adequate RSA
service. Frequency and phase differences among signals from the remote sites (110-113) to the satellite (130) are synchronized to avoid frequency -and phase- drift.
cell site (140) has a co-located cell site converter (145) which converts satellite signals to signals for the MTSO and vice-versa. Remote converter sites (110-113) communicate with the satellite (130) and with the mobile units (101, 102) in given geographical areas. A single satellite link is sufficient for adequate RSA
service. Frequency and phase differences among signals from the remote sites (110-113) to the satellite (130) are synchronized to avoid frequency -and phase- drift.
Description
WO 92/00636 '~ Pcr/uss1/o43ol ,~ i.
SATELLlTE MOBILE COMMUN~CAnON SYSTEM
FO~ ~URAL SERV~CE AREAS
Field of the Invention r The present invention relates generally to satell;ite mobile communications systems and more panicularly to a satelliLe link for rural service area mobile telephone systems.
BACKGROUND OF THE ~NVENl~ON
A good mobile telephone cellular communications system should appear to be just like a r~gular household or business telephone system from the user'sperception.
When a user in a car (the "mobile unit ) desires to make a call. the mobile telephone unit scans the set-up channe.s. selects the strongest and locks on IS for a certain time. Euh cell site is assigned a dif~erent set-up channel, so locking on to the strongest usually means selectir.g the nearwt cell site in wha~ is terrr.ed a "se]f-location" scheme. Such a scheme does not rc~uire the cell si~es ~o loca~e the mobile unit, but for calls to mobik units. thc paging process is lon~er 'oecause no mobile unit location infonnation i~ ava,ilsble at the cell sites.
A ca]l request ~.ent from the mobile unit i9 teceived b$~ a cell sile which typicslly ~elect~. a ditecti~,~c antenna .tor tne communica~ions channeh At the s~me time, the cell site also sends a rcque~ for a voice ch~nnel to the hiobile Telephone Switching Office (MTSO) vi~ ~ high~speed data link. The r~lTSO
~elects sn sppropriate ~oice channel for the c~ll and the cell site links lhe channel 25 with the directive antenna to the mobilc unit. l~e ~ITSO also connec~s t~e wu~-line party through the telephanc compsnS~ cenu31 of fice~
A call from a land line party ~o ~ mobile unit yoes fir~t to the telephonc company cenual office which recoyni2es tt~at thc num~ct i~ for ~ mobile uni~
forwuds the ca~l lO the MTSO. Tlle h1TSO ~end~ a p~in~ me~ e ~o cettain 30 cell site~ based on the mobile unit numbct and a se3tc~ otithm. Esch c~ ite transmits the pap ~n its own set up ct~nncl~ The mQ~ilc umt recn~ni~cs It~c nwn idcntificalion on a ~tron~ ~u~ up c~snncl. I~k~ ont~ nd te~n~ ~o th~ eell site instructlon to tune ~o ~n assl~ncd ~ice ch~nnel.
Cellular mobile ~tcms in thc t~nitc~ Sut~s n~fe hecn designated ~
3~ Cellular GeogrDphic Sen~ice Area~ (CGSA~ Thc 13t~st few hundred c~tics ~re called Mctropollt~n Stalistical Areas ~lSA~ ~n~ thc rest ~f the C:GS.~s ar~ c~lled Rural Service Are~ (RSA~. RSAs ~rc t~pic~lly ~djxcnt tn MSAs, 3nd ~ Iso be scattercd u remotc geo~rap~ic~l sp~t~ thtou~lou~ ~ country.
SATELLlTE MOBILE COMMUN~CAnON SYSTEM
FO~ ~URAL SERV~CE AREAS
Field of the Invention r The present invention relates generally to satell;ite mobile communications systems and more panicularly to a satelliLe link for rural service area mobile telephone systems.
BACKGROUND OF THE ~NVENl~ON
A good mobile telephone cellular communications system should appear to be just like a r~gular household or business telephone system from the user'sperception.
When a user in a car (the "mobile unit ) desires to make a call. the mobile telephone unit scans the set-up channe.s. selects the strongest and locks on IS for a certain time. Euh cell site is assigned a dif~erent set-up channel, so locking on to the strongest usually means selectir.g the nearwt cell site in wha~ is terrr.ed a "se]f-location" scheme. Such a scheme does not rc~uire the cell si~es ~o loca~e the mobile unit, but for calls to mobik units. thc paging process is lon~er 'oecause no mobile unit location infonnation i~ ava,ilsble at the cell sites.
A ca]l request ~.ent from the mobile unit i9 teceived b$~ a cell sile which typicslly ~elect~. a ditecti~,~c antenna .tor tne communica~ions channeh At the s~me time, the cell site also sends a rcque~ for a voice ch~nnel to the hiobile Telephone Switching Office (MTSO) vi~ ~ high~speed data link. The r~lTSO
~elects sn sppropriate ~oice channel for the c~ll and the cell site links lhe channel 25 with the directive antenna to the mobilc unit. l~e ~ITSO also connec~s t~e wu~-line party through the telephanc compsnS~ cenu31 of fice~
A call from a land line party ~o ~ mobile unit yoes fir~t to the telephonc company cenual office which recoyni2es tt~at thc num~ct i~ for ~ mobile uni~
forwuds the ca~l lO the MTSO. Tlle h1TSO ~end~ a p~in~ me~ e ~o cettain 30 cell site~ based on the mobile unit numbct and a se3tc~ otithm. Esch c~ ite transmits the pap ~n its own set up ct~nncl~ The mQ~ilc umt recn~ni~cs It~c nwn idcntificalion on a ~tron~ ~u~ up c~snncl. I~k~ ont~ nd te~n~ ~o th~ eell site instructlon to tune ~o ~n assl~ncd ~ice ch~nnel.
Cellular mobile ~tcms in thc t~nitc~ Sut~s n~fe hecn designated ~
3~ Cellular GeogrDphic Sen~ice Area~ (CGSA~ Thc 13t~st few hundred c~tics ~re called Mctropollt~n Stalistical Areas ~lSA~ ~n~ thc rest ~f the C:GS.~s ar~ c~lled Rural Service Are~ (RSA~. RSAs ~rc t~pic~lly ~djxcnt tn MSAs, 3nd ~ Iso be scattercd u remotc geo~rap~ic~l sp~t~ thtou~lou~ ~ country.
2 Pcr/US91/W3ol ., ;~
2ér detail regarding mobile communications systems, see Mobile Cellular Telecommunications Svstems (McGraw-Hill l9X9) by William C.Y.
Lee.
An impottant problem in cellular communications is to provide cost-S effective coverage to RSAs that provides adequate ser~ice to rural users. Furtherthe RSA system must not interfere with MSA covetage. The cost-effective aspect is crucial in RSAs b~catlse of the typic~lly limited number of users.
Accordingly, it is an object of the present invention to provide a new cost-effective mobile communications Sy~T~.
It is a further object of the ptesent in~ention to provide a mobile communications system suitable fot roral senrice areas.
It is another object of the present in~ren~ion to provide a mobile communications system which pro~,rides adequaoe senrice at minimal comple~ity.
cost, and power.
lS
~DF 1 HE ~E~ON
The present invention provides a mobilc communications system which operates in conjunction with a communications satcllite and a Mobile Telephone Switching Office ~hll SO). The sys~em communic~ wilh a plurality of mobile ~o units via the saulliu. ll~ere i~ at Icast one cell sitc with a ce11 site con~ner locate~ there. ~e cell ~i~c con~erler con~effs ~;ign~l~ from the satellite to ~i~nals for ~he MTSO and vice~versa. The cell site comener ~as an antenna for communicating with the ~atellite and ~ ~ITSO communication means fo-communicating with thc mobile tclcphonc cwitching of fice. For communicatin~
2S with the mobile units, there ue remote con~tencr sites for covera~e of ~ cn geographical areas. Each remotc ~itc 1~ a tem~te con~ener for con~ening ~atclliu signa~s to mobile unil ~ignals and ~ice~ Each o~ the remote convencrs includcs an antenna for communic~ in~ wittl the ~atellite, and lransmillcr and a recei~er for communialing witn tllc mnbile unit~.
Becau~c of thc gcogtaphic;~lly widely ~catt~ tcm~te conve~r ~iitc~.
there may bc some frequency and pha~ ~ilfcsenc~ ~mnn~ nals ~tom thc rcmote si~c~ to the salel1itc. Tlle presen~ in~enti~n tnctefore synchtoni~ ~e ~ignal~ from the temote $ite~ to ~hc ~3telli~ o RC tO~ a~id ~equeney ~nd ph3~u-dnh.
3S The prescn~ in~ntion i~ ideal)y suiled ~t rut~ ~ccrVlcc 3~ea ~RS~) mohilecommunication~ becau~e ( I) it pto~/ide~ a ~oa~ ~eo~taphlcal co~re~3c whieh c~nincludc isolatcd spots, (2) il i~ operable throu~h a sin~le communications ~tellite link which is ~enerally adequate ~or RS~s ~ecause ot I typically lower ~nlume nt Wo 92/00636 Pcr/uss1/o43o1 20g80,52 '' calls in RSAs, thereby significan~ly reducing costs. (3) minimal equipment and comple~ity is required at the remote converter ci~ thereby producing even more cost savings and achieving efficiency of operation. and (4) the RSA system shares one MTSO with MSA systems thereby further re~ucing cost and equipment requirements.
The placement of the cell-site con~erter at the cell site and the remote conver~ers at the remote sites and the use of the single satellite link allow the realization of the above advantàges of the present invention.
The further underslanding of the natmc and ad~rantages of the presen invention may be realized by referencc to the De1ailed Description of the Invention and the anached drawings.
BR-EF DESCRlPllO~ OF ~HE DRAWINGS
Figure I is a schematic diagram of a satellite mobile communications IS system according to the present invcntion.
Figure 2 is a schematic diagram of an e~cmp1ar~ cel1 si~e comer~er located in a RSA cell site according to the ptescnt invention.
Figure 3 is a schematic reptesentation of a ph~e-lock loop as utilized in a cell site con~vetter acco~ding lo tne p~ent in~ention.
ZO Figure 4 is a schematic diagram of a ~mote con~ener at a RSA con~cner e accotding to the p~esent invention.
Figure 5 is à schematic repre~ntation of ~ p~l~ lock loop ~s utililed in a remote con~/ette~ at a RSA sitc acco-din~ to the p~senl invention.
Figure fi schematically ~ho~ a satleUi~ etw~en an MTSO ~nd a 2S Cenual Office (CO~ ucotdin~ to tnc ptesen~ in~enùon.
Communications satcllitc~ ~ctin~ a~ ndt~Afrcquency re,qeater~ t')~
uan~pondets~ are commnnly u~cd to prn~ide linl~ f~r e~nh ~sed communications. The satellites ~re typic3;tly in ~ ~tinn.~Ary or~it and ~encr~tly capable of lineAofAsigl~l microw~ve 1inkc witl~ tions. Cammunic3lians ~a~lli(es fealute widc b~ndwidt~c f~t hi~h ch~ el ~Ap~Cit,~ fnr vr,ice. ~atl~ mtl ima~c communicalion~ lherct~y pt~idin~ multuple ~ccss s~ that ~ lar~ num~e~
of usets can communicale via t~le ~me ~tellit~ Thus~ communicati~n~s salcllites 3S may he ide~lly u~lized fo~ mo~ile telephone cQmmunicatian.
In a typical saullite mnbile telephone ~ cm. ~ tclcphnne c~ ntcr~ an e~h station whetc il i~ combined wi~ athe~ si~n~lls which m~ldulatc ~n uptink microw~e c~met ha~ing PA frequenc,Y af typtcaAly 6 GHt.~ The ~ellite r~celtfcs WO 92/00636 Q`~ q pcr/us91/~
the signal, amplifies it, and down-conYerts to the downlink carrier at typically 4 GHz, At the recei-ring earth station. the signal is amplifled by a low-noise receiver, down-converted to an ir~termediate fr~quency, ty~pically 800 MHz, and transmitted by terrestrial facilities.
One prior art approach to provide mobile telcphone service to Rural Service Areas (RSA) is to utilize sa~eUites to provide communications link~
between a Mobile Telephone Switching Of fice ~SO) and cell sites with a cell site a~ every RSA site. Such a sys~em has the disad~rantage of e~tremely costly aperation. Each cell site req~ires e~pensj~e e~ipment to serfice its ceU.
lo Funher, for the typically large areas in RSAs, thc tcrres~ial microwave network requirements for cannecting the MTSO ~o thc cell sites are very costly and the RSA system does not share an MTSO with eI~s~ing Metropolitan S~atistical Area (MSA) systems.
According IO the present invention. a cost- ffective singie sa~elli~e link is IS used to link a pluraljty of remote con~erter siu:s al different remote RSA sites and a "vinual" ~SA cell si~e, which comp~ cell si~e and a cell-site con~erte~.
The remote convener sites receive and ~ansmit UHF signals to the mobile unt~s in the remote RSA ~ites. The signals are c~n~/ertcd to satelU~e communication frequencies termed Supet High FrtqKnCy (SH~:) for communication over the single satellite link lO the satellite, Thc satellite communicates via S~ by either up-con~ening ftom UHF or do~con~ening ~o t~ 9~ ~e RSA cell site which is communicating with the MTSO. 1n tne pre~ctTed em~odiment~ the RSA cell ~ite is co located with the MlSO. A sin~lc saul}i~e link p~esently c~n m~e apptoximately 40~S0 channels. Th~se channels arc sl~ared by multiple RSA
2S comener sites. The use of a single link ptovides considerable cosl sa~ing~ ~nd is adequate for the typical ~falume of RSA c~lls Ttle use of limited numbets of RSA cell sites with 1heit re~uiremen~ also ptescn~s c~n~iderable cost sa~ring The convener siles ue relalively ine~pens~ ~n~ simple to opetate~
The scheme of the pre~en~ tn~ntion il ~wn in Fil~ure 1. E:tcmpl~
~0 mobile units 1~1 and 102 communic~tc n~ ith c~cmpl~ cont~encr ~ites 160, 161, 162, and 163. Each af rematc con~cnct ~ite~ 16t) 163 include ~ma~c convcncrs l 1 0-11 3 which cach campn~ cxcmplirlcd ~y l ~ I ~n convene~ t~llillet l~2. and a tcce1~e~ 1~3. Each P~SA c~n ~ ~n~ed by one or more remotc con~eners~ Rcmote con~ne~s 11~ l 13 communic~te via 3S SHF with a communicatlons satellite 130. Sa~ellile 13~ communicates via St~Fwi~ inu~ll RSA cell sile 140 whicb is communica~ively coupled to a ~ITSQ
150. VinualRSAcellsile 140compnsesan-ntenna 141 mdlcell~ù~ccnnve~e~
lilS~ which convens SH~: si~nDIs to UHF
Wo 92/00636 5 ~ 0 8 8 0 5 2 Pcr/l IS91/04301 Downlink SHF signals from satellite 130 to remote converters 110-113 and to RSA cell site 140 are combined at satellite 130 in a manner known in the art and retransmitted to the specific remote converters and RSA cell sites in the predetermined communication channels Uplink SHF signals from remote conreners 11~113, howerer, originate from geographically scattered sites and may e~perience some frequency and phase differences among the differnt remote sites Since the t~HF signals (typically 800 MHz) are converted to much highe;r fr~quency uplink SHF signals (typically 6 GHz), a small frequency and/or phasc drift in UHF will cause a large lo drift when up-con~verled to SH}: and ~hen dowT~conoerted IO UHP, Therefote the present invention provides a mcans and mcthod lo synchronize the uplink SHF signals to the satellite, Figure 2 is a schemalic diagram of an e~emplary cell site convener 200 located in a RSA cell site SUCtl as 140. A direct heterodyne sys~em is u(ilized in lS which the OUtpUl signal f~equenc~ is linearly down or u~convening the inpu~
signal frequency by means of a phase-lock loop 212 fed by a si~nal geneta~ed b~ra local oscillator 210, According to one cmbodimen~ of the ptesent it~ention a pilot signal is also generated to pto~ride a common sowce clock ~cfetence upon which the uplink SHF signals from con~r 200 may ~ nch~onized This is panicu1stly diKd becau~e satcllite 130 ttatl911~it~ t~e ~ s IO ~ridely-~cal~ered KSA remo~econverter sites 160 163.
First consider a uan~mi~on from ce}l i~c con~ner 200 to sa~llile 130 A UHF signsl i~ recei~ed ftom MTS0 150~ C~ll sit~ convener 2ao may ~e 2~ communicatively coupled lo P~SI'S0 lS0 by any ~it~ble means. For e~ample.
cell site comerter 200 may ~e co~ ted witn ~rrso 1S0. connected ~y a ~t carrier line or microwa~e caupled. Loc~l oscilhfor ~10 ~encra~ a 10 hlHz pilo~
si~nal which is phase-lockcd by pna~e llt l~op 21 . Mj~ter 201 u~mi~es ~e UHF ~ignal to SHP and filter ~0 p~ses eitt~r tbe bi~b or low band b~
predetennined choice. A SHF amplifiKr ~ ampU~ t~lc u~nat for t~mi~sion throu~h circulator 224 to satcllite 1~0 ~ SHF an~nna 141 T~c 10 h~tt ii~n~l from local oscillator 210 is ~Iso sent ~n PlN m~ulato~ 230 fnr ampli~ude modulalion of the sign~l al SHF ~4uenc~ un~ e conuol of pha~e-lack toap 212. Thus phase lock loop 212 pro~ides a SHF c3r~iet ~i~nat ~i~t~ 3 common phase provided b~ lhe 10 MHz pilo~ ~ign~l genetalcd by lacal ascilla~or 210 The output of PIN modulalor 230 is coupled ~o ~e oulpu~ of SHF amplirler lha~ a SHF pilot si~nal is ttans~tnilted witn ~hc S~F si~nD~I lo salelli~e 130 Wo 92/00636 ,~ 6 pcrtuss1/w3 Phase-lock loop 212 is shown schematically in Figure 3. A phase-lock loop is a circuit for synchronizing a variable oscil~a~or w~th the phase of transmitted signal. The 10 MHz pilot signal from local oscillalor 210 is fed into a mixer 301 which is coupled with a local replica signal derived from a dividing 5 circuit 30~, which in turn is coupled to a voltage40ntrolled oscillator (VCO) 310.
The output of mixer 301 is the error signal passing through a low-pass filter 320 which jD turn is controlling VCO 310. The output of VCO 310, before division by dividing circuit 305, is just the SH;F carrier sig~nal The SHF carrier is coupled to PIN modulator 230 which modula~ the 10 MHz pilot signal onto the SHF
~o carrier, Thus, for the uplink to satellite l30. VCO 310 pro~ides the S~;
~typically 6 GHz) carrier frequency for u~con~rcrhng UHF signals at mi~er ~O l (node a) and also for u~convening the lO MHz pilo~ si~nal from local oscillator 210 at PIN modulator 230 (node c~ e modulated pilot signal at SHF
frequencies is provided at node b. Thus. thc u~converted UHF siynal and the lO
IS MHz pilot signal on a SHF carrier are com~ined at node b for transmission by SHF antenna 141 to satellite 130.
Returning to Figure 2, cons~dering rccep~i~n and conversion of SHF
satellite signals, a SHF signal i~ recei~ed a~ SHF alltenna 141. Circulator ~-~directs the signal to filter 240 which pa~cs thc nigh or low ~and (whichel~er is 20 opposite to that pas~ed bl~ filter no in the uansmis~uon ptocess to satellite l 30)~
The signal i5 down-mi~ed at mi~er 202 wi~ich is also co~pled to ph~e-lock loop 214, which lock~ on ~he 10 ~t pi101 9igna] from loc~J oscillalnr 210 ~md down mko~ the downlink SHF ~ Pb~se-lack lo~p 2l4 operates jUSt as p~ e-l~ck loop 212 except for a VC~ (not sho~n) fat ~enentin~ do~nlink mi~in~
2S frequencies. The SHF ~ignal ha~ now ~a) conren:d to U~lF with the pilot signal pro~iding the J~rnchronization~ The UHF si~ then amplified ~y amplirler 242 for tran~mi~ion to RS~ ccll ~ite l~lO ~o~ Fi~c 1~.
Fi~ure 4 is a ~chematic diag~m of ~ tcmotc cQn~ncr 400 al a RSA
remote con~rerter site such a~ 16~163 ~of Fi~ute l)~ Remote con~erte~ 4 30 utilizes direct heterodyne circuitr~ ~nd thc ~1amc S~ atcllite frequencic~ a~ convener 200 (of Fi~ute 2~.
An cxcmplary mobile uni~ 4n I tt~miL~ U~IF *i~n~ la ~ecei~in~ anlenna 423. The si~nal is filteted by rPîtet ~3î ~d up mi~cd to uplink SHF a~ mhc~ ~3 using a common pha~é pro~ided by a 10 hl~l~ pil~ si~nal ~y me~c ot a pn~se ~5 lock loop ~. Ther~le-, the SHF si~n~ is filt~re~ ~ filtcr ~3' t~ confine the si~nal lo it~ ptedetennined frequency t;Ul~C. and 3mplificd ~y unplificr ~3S. The common phase pro~ided by t~e 10 MH~ pllot ~ c~rried hy t~lC amplific~i uplink SHF si~ns~l and is directed lo antenn3 ~ l ~ c~rculstor ~3~
W0 92/00636 7 2 Q g 8 0 ~ 2 For IJHF paging and transmitting infonnation, modulated satellite SHF
downlink signals are receh~ed at antenna 441, circulated to the parallel configuration of band pass filter (BPI:) 410 and mi~er 401. The downlink signal from satellite 130 can be meant for a remote conYener site or a RSA cell site (as shown in Figure 1), Which type of site is dete~mined by the predetermined choice of the UHF upper or lower side band. Tha~ is. if the upper side band is chosen for the transmission al the RSA cell sile. then the lower side band is used for the transmission at the ~note coo~rener site~
The Sl~; ~i~al from band-pass filter 410 is sdeaed by detector 450 o which is an envelope detector, The 10 MH~ pilot si~ iS recovered at node c and its upperband noise is redtlced by a low-pass filta 451 Phase-lock loop 445 pro~vides the satetlite downlink camet. which fr~ency is determined by the panicular satellite. Phæ-lock loop 444 pfovida the satellite uplink camer. By recovenng the 10 MHz signal. thac iS no ~t of a local oscillalot (such IS as 210 of Figure 2), the signals being ~mchroni~cd by the reco~/ered common 10 MHz pilot signal to a common phase al SHF for ~11 RSA remote con~enet si~
The SHF signal i~ down-cQn~ed n mi~a 402 via ph;~ie-lock loop ~45, f~lured b~ filur 433 and t~ansmitud by uu~ ing antenna 422 to mobile uni~
401, Figure S ~chematicallr ~ow~ p~sc-locl~ l~op ~44 which oper~u~ in ~e same fashion as ph~e-lock loop 212 of Fi~ute 3 w~tls ~JCO S10 opcratin~ a uplink SHF ftequencie~.
An alternadvc embadimcnl of ~ prcsent inllenuon is ~o odli~c ~
precision clock at the cell site to pto~ride uplinlt syncl~mni~ation of tne s~nals 2.S from the remote conve ter ~ites. This a~n bc ~d b~ lla~nn~ ~ clock pro~iding clock erron of subltanti~ oor k~ The clock req~irc~ an initial line-up ~et-up and a petiodic alignment chcck In i~ ptOpet ~i~nal synchroni~ation.
A telephone ~y~tem ~pically ba~ a Cenual l)ffice (C()) wbicl~ ~t~
the wirelincs for the lelephonel in the ~n:a ~ RS~ ~ould ba~e ~ucl~ a CO wit~in its area. Ir there is a CO in Ihæ RS~. tllen c311~ ~tom mobile units an~ l~aî
landline~ would be local calls~ tf t1~ ~11 Sl ) i~ l~csted in ~ Mettopolitan Stat~s~ical Area ~MSA) tar from ~e Ct~ ~ittlin lllc RS~ then the c311s f~om mobilc uniu to local 13ndlines may bccomc bn~ dis~ancc c~ . T~ ~oid thc 3S mobi1c call~ from bccomin~ lon~ di~nce call~ tnc communicalinn ~etwe~n the MTSO and Ihe CO cs~n be m~de ~ia tlle ~t~Uitc Imk~
Figurc 6 schcmalically show~ ~n 9 nn~ement accotding tn t~c p~ent in~/ention wheteby a satellite link between ~rrso ~nd cn is mlde. ~
WO 92/00636 ~ 8 pcr/us91/w3 exemplary home is connected by wireline 603 and C0 610 which in tum is connected by wireline 604 to a data bank 621 which is located at MTS0 620.
Data bank 621 performs the analog ~o digital and bit rate conversions required by MTSO 620, as are known in the communications a~ MTS0 620 is 5 communicatively coupled to RSA cell sites as shown in Figure 1. A MTS0 convener 623 communicates with satellile 130 v~a anteMa 622. MTS0 converter is a simple baseband up/down SHF con~erter which allo vs communications with satellite 130 for the purposes lin~ng ~S0 6~a with co 640. co 640 communicates with sa~lite 130 ~a antama 632 ~ich is connected to a C0 10 converter 634 which in turn is connected by a data bank 631.
The present in~ention has the fun~er ad~antage that for paging of the mobile units, only a single hop from the cell site up to the saullite then down to the mobile units is required. That is. util~ng a satellite a110ws a downlink page lO all converter sites simultaneously In land-based ceUular systems. multiple 1S hops using microwa~e backbone systems from cell site to cell site are typical1y required.
While the a~o~e description pro~rides a full and complete desc~ip~ion of Ihe preferred embodiments of the ptesent imention. vartous modificalions alurnau constmctjons and equi~ralents may be cmployed. For e~tample. lhe 20 present invention is not limited to so called l'Ut;~ serrice areas, t~Ut C~Uladvantageousl~r pro~ide adequate sennce ~o any ~i~tion where there sre fewer mobile u~ers, as in a le~s developed countr~ etefore. the above desc~pùon and illust ations should not be cons~ued as limi~in~ the scope of the in~enùon which is defined by the followin~ claim~
2ér detail regarding mobile communications systems, see Mobile Cellular Telecommunications Svstems (McGraw-Hill l9X9) by William C.Y.
Lee.
An impottant problem in cellular communications is to provide cost-S effective coverage to RSAs that provides adequate ser~ice to rural users. Furtherthe RSA system must not interfere with MSA covetage. The cost-effective aspect is crucial in RSAs b~catlse of the typic~lly limited number of users.
Accordingly, it is an object of the present invention to provide a new cost-effective mobile communications Sy~T~.
It is a further object of the ptesent in~ention to provide a mobile communications system suitable fot roral senrice areas.
It is another object of the present in~ren~ion to provide a mobile communications system which pro~,rides adequaoe senrice at minimal comple~ity.
cost, and power.
lS
~DF 1 HE ~E~ON
The present invention provides a mobilc communications system which operates in conjunction with a communications satcllite and a Mobile Telephone Switching Office ~hll SO). The sys~em communic~ wilh a plurality of mobile ~o units via the saulliu. ll~ere i~ at Icast one cell sitc with a ce11 site con~ner locate~ there. ~e cell ~i~c con~erler con~effs ~;ign~l~ from the satellite to ~i~nals for ~he MTSO and vice~versa. The cell site comener ~as an antenna for communicating with the ~atellite and ~ ~ITSO communication means fo-communicating with thc mobile tclcphonc cwitching of fice. For communicatin~
2S with the mobile units, there ue remote con~tencr sites for covera~e of ~ cn geographical areas. Each remotc ~itc 1~ a tem~te con~ener for con~ening ~atclliu signa~s to mobile unil ~ignals and ~ice~ Each o~ the remote convencrs includcs an antenna for communic~ in~ wittl the ~atellite, and lransmillcr and a recei~er for communialing witn tllc mnbile unit~.
Becau~c of thc gcogtaphic;~lly widely ~catt~ tcm~te conve~r ~iitc~.
there may bc some frequency and pha~ ~ilfcsenc~ ~mnn~ nals ~tom thc rcmote si~c~ to the salel1itc. Tlle presen~ in~enti~n tnctefore synchtoni~ ~e ~ignal~ from the temote $ite~ to ~hc ~3telli~ o RC tO~ a~id ~equeney ~nd ph3~u-dnh.
3S The prescn~ in~ntion i~ ideal)y suiled ~t rut~ ~ccrVlcc 3~ea ~RS~) mohilecommunication~ becau~e ( I) it pto~/ide~ a ~oa~ ~eo~taphlcal co~re~3c whieh c~nincludc isolatcd spots, (2) il i~ operable throu~h a sin~le communications ~tellite link which is ~enerally adequate ~or RS~s ~ecause ot I typically lower ~nlume nt Wo 92/00636 Pcr/uss1/o43o1 20g80,52 '' calls in RSAs, thereby significan~ly reducing costs. (3) minimal equipment and comple~ity is required at the remote converter ci~ thereby producing even more cost savings and achieving efficiency of operation. and (4) the RSA system shares one MTSO with MSA systems thereby further re~ucing cost and equipment requirements.
The placement of the cell-site con~erter at the cell site and the remote conver~ers at the remote sites and the use of the single satellite link allow the realization of the above advantàges of the present invention.
The further underslanding of the natmc and ad~rantages of the presen invention may be realized by referencc to the De1ailed Description of the Invention and the anached drawings.
BR-EF DESCRlPllO~ OF ~HE DRAWINGS
Figure I is a schematic diagram of a satellite mobile communications IS system according to the present invcntion.
Figure 2 is a schematic diagram of an e~cmp1ar~ cel1 si~e comer~er located in a RSA cell site according to the ptescnt invention.
Figure 3 is a schematic reptesentation of a ph~e-lock loop as utilized in a cell site con~vetter acco~ding lo tne p~ent in~ention.
ZO Figure 4 is a schematic diagram of a ~mote con~ener at a RSA con~cner e accotding to the p~esent invention.
Figure 5 is à schematic repre~ntation of ~ p~l~ lock loop ~s utililed in a remote con~/ette~ at a RSA sitc acco-din~ to the p~senl invention.
Figure fi schematically ~ho~ a satleUi~ etw~en an MTSO ~nd a 2S Cenual Office (CO~ ucotdin~ to tnc ptesen~ in~enùon.
Communications satcllitc~ ~ctin~ a~ ndt~Afrcquency re,qeater~ t')~
uan~pondets~ are commnnly u~cd to prn~ide linl~ f~r e~nh ~sed communications. The satellites ~re typic3;tly in ~ ~tinn.~Ary or~it and ~encr~tly capable of lineAofAsigl~l microw~ve 1inkc witl~ tions. Cammunic3lians ~a~lli(es fealute widc b~ndwidt~c f~t hi~h ch~ el ~Ap~Cit,~ fnr vr,ice. ~atl~ mtl ima~c communicalion~ lherct~y pt~idin~ multuple ~ccss s~ that ~ lar~ num~e~
of usets can communicale via t~le ~me ~tellit~ Thus~ communicati~n~s salcllites 3S may he ide~lly u~lized fo~ mo~ile telephone cQmmunicatian.
In a typical saullite mnbile telephone ~ cm. ~ tclcphnne c~ ntcr~ an e~h station whetc il i~ combined wi~ athe~ si~n~lls which m~ldulatc ~n uptink microw~e c~met ha~ing PA frequenc,Y af typtcaAly 6 GHt.~ The ~ellite r~celtfcs WO 92/00636 Q`~ q pcr/us91/~
the signal, amplifies it, and down-conYerts to the downlink carrier at typically 4 GHz, At the recei-ring earth station. the signal is amplifled by a low-noise receiver, down-converted to an ir~termediate fr~quency, ty~pically 800 MHz, and transmitted by terrestrial facilities.
One prior art approach to provide mobile telcphone service to Rural Service Areas (RSA) is to utilize sa~eUites to provide communications link~
between a Mobile Telephone Switching Of fice ~SO) and cell sites with a cell site a~ every RSA site. Such a sys~em has the disad~rantage of e~tremely costly aperation. Each cell site req~ires e~pensj~e e~ipment to serfice its ceU.
lo Funher, for the typically large areas in RSAs, thc tcrres~ial microwave network requirements for cannecting the MTSO ~o thc cell sites are very costly and the RSA system does not share an MTSO with eI~s~ing Metropolitan S~atistical Area (MSA) systems.
According IO the present invention. a cost- ffective singie sa~elli~e link is IS used to link a pluraljty of remote con~erter siu:s al different remote RSA sites and a "vinual" ~SA cell si~e, which comp~ cell si~e and a cell-site con~erte~.
The remote convener sites receive and ~ansmit UHF signals to the mobile unt~s in the remote RSA ~ites. The signals are c~n~/ertcd to satelU~e communication frequencies termed Supet High FrtqKnCy (SH~:) for communication over the single satellite link lO the satellite, Thc satellite communicates via S~ by either up-con~ening ftom UHF or do~con~ening ~o t~ 9~ ~e RSA cell site which is communicating with the MTSO. 1n tne pre~ctTed em~odiment~ the RSA cell ~ite is co located with the MlSO. A sin~lc saul}i~e link p~esently c~n m~e apptoximately 40~S0 channels. Th~se channels arc sl~ared by multiple RSA
2S comener sites. The use of a single link ptovides considerable cosl sa~ing~ ~nd is adequate for the typical ~falume of RSA c~lls Ttle use of limited numbets of RSA cell sites with 1heit re~uiremen~ also ptescn~s c~n~iderable cost sa~ring The convener siles ue relalively ine~pens~ ~n~ simple to opetate~
The scheme of the pre~en~ tn~ntion il ~wn in Fil~ure 1. E:tcmpl~
~0 mobile units 1~1 and 102 communic~tc n~ ith c~cmpl~ cont~encr ~ites 160, 161, 162, and 163. Each af rematc con~cnct ~ite~ 16t) 163 include ~ma~c convcncrs l 1 0-11 3 which cach campn~ cxcmplirlcd ~y l ~ I ~n convene~ t~llillet l~2. and a tcce1~e~ 1~3. Each P~SA c~n ~ ~n~ed by one or more remotc con~eners~ Rcmote con~ne~s 11~ l 13 communic~te via 3S SHF with a communicatlons satellite 130. Sa~ellile 13~ communicates via St~Fwi~ inu~ll RSA cell sile 140 whicb is communica~ively coupled to a ~ITSQ
150. VinualRSAcellsile 140compnsesan-ntenna 141 mdlcell~ù~ccnnve~e~
lilS~ which convens SH~: si~nDIs to UHF
Wo 92/00636 5 ~ 0 8 8 0 5 2 Pcr/l IS91/04301 Downlink SHF signals from satellite 130 to remote converters 110-113 and to RSA cell site 140 are combined at satellite 130 in a manner known in the art and retransmitted to the specific remote converters and RSA cell sites in the predetermined communication channels Uplink SHF signals from remote conreners 11~113, howerer, originate from geographically scattered sites and may e~perience some frequency and phase differences among the differnt remote sites Since the t~HF signals (typically 800 MHz) are converted to much highe;r fr~quency uplink SHF signals (typically 6 GHz), a small frequency and/or phasc drift in UHF will cause a large lo drift when up-con~verled to SH}: and ~hen dowT~conoerted IO UHP, Therefote the present invention provides a mcans and mcthod lo synchronize the uplink SHF signals to the satellite, Figure 2 is a schemalic diagram of an e~emplary cell site convener 200 located in a RSA cell site SUCtl as 140. A direct heterodyne sys~em is u(ilized in lS which the OUtpUl signal f~equenc~ is linearly down or u~convening the inpu~
signal frequency by means of a phase-lock loop 212 fed by a si~nal geneta~ed b~ra local oscillator 210, According to one cmbodimen~ of the ptesent it~ention a pilot signal is also generated to pto~ride a common sowce clock ~cfetence upon which the uplink SHF signals from con~r 200 may ~ nch~onized This is panicu1stly diKd becau~e satcllite 130 ttatl911~it~ t~e ~ s IO ~ridely-~cal~ered KSA remo~econverter sites 160 163.
First consider a uan~mi~on from ce}l i~c con~ner 200 to sa~llile 130 A UHF signsl i~ recei~ed ftom MTS0 150~ C~ll sit~ convener 2ao may ~e 2~ communicatively coupled lo P~SI'S0 lS0 by any ~it~ble means. For e~ample.
cell site comerter 200 may ~e co~ ted witn ~rrso 1S0. connected ~y a ~t carrier line or microwa~e caupled. Loc~l oscilhfor ~10 ~encra~ a 10 hlHz pilo~
si~nal which is phase-lockcd by pna~e llt l~op 21 . Mj~ter 201 u~mi~es ~e UHF ~ignal to SHP and filter ~0 p~ses eitt~r tbe bi~b or low band b~
predetennined choice. A SHF amplifiKr ~ ampU~ t~lc u~nat for t~mi~sion throu~h circulator 224 to satcllite 1~0 ~ SHF an~nna 141 T~c 10 h~tt ii~n~l from local oscillator 210 is ~Iso sent ~n PlN m~ulato~ 230 fnr ampli~ude modulalion of the sign~l al SHF ~4uenc~ un~ e conuol of pha~e-lack toap 212. Thus phase lock loop 212 pro~ides a SHF c3r~iet ~i~nat ~i~t~ 3 common phase provided b~ lhe 10 MHz pilo~ ~ign~l genetalcd by lacal ascilla~or 210 The output of PIN modulalor 230 is coupled ~o ~e oulpu~ of SHF amplirler lha~ a SHF pilot si~nal is ttans~tnilted witn ~hc S~F si~nD~I lo salelli~e 130 Wo 92/00636 ,~ 6 pcrtuss1/w3 Phase-lock loop 212 is shown schematically in Figure 3. A phase-lock loop is a circuit for synchronizing a variable oscil~a~or w~th the phase of transmitted signal. The 10 MHz pilot signal from local oscillalor 210 is fed into a mixer 301 which is coupled with a local replica signal derived from a dividing 5 circuit 30~, which in turn is coupled to a voltage40ntrolled oscillator (VCO) 310.
The output of mixer 301 is the error signal passing through a low-pass filter 320 which jD turn is controlling VCO 310. The output of VCO 310, before division by dividing circuit 305, is just the SH;F carrier sig~nal The SHF carrier is coupled to PIN modulator 230 which modula~ the 10 MHz pilot signal onto the SHF
~o carrier, Thus, for the uplink to satellite l30. VCO 310 pro~ides the S~;
~typically 6 GHz) carrier frequency for u~con~rcrhng UHF signals at mi~er ~O l (node a) and also for u~convening the lO MHz pilo~ si~nal from local oscillator 210 at PIN modulator 230 (node c~ e modulated pilot signal at SHF
frequencies is provided at node b. Thus. thc u~converted UHF siynal and the lO
IS MHz pilot signal on a SHF carrier are com~ined at node b for transmission by SHF antenna 141 to satellite 130.
Returning to Figure 2, cons~dering rccep~i~n and conversion of SHF
satellite signals, a SHF signal i~ recei~ed a~ SHF alltenna 141. Circulator ~-~directs the signal to filter 240 which pa~cs thc nigh or low ~and (whichel~er is 20 opposite to that pas~ed bl~ filter no in the uansmis~uon ptocess to satellite l 30)~
The signal i5 down-mi~ed at mi~er 202 wi~ich is also co~pled to ph~e-lock loop 214, which lock~ on ~he 10 ~t pi101 9igna] from loc~J oscillalnr 210 ~md down mko~ the downlink SHF ~ Pb~se-lack lo~p 2l4 operates jUSt as p~ e-l~ck loop 212 except for a VC~ (not sho~n) fat ~enentin~ do~nlink mi~in~
2S frequencies. The SHF ~ignal ha~ now ~a) conren:d to U~lF with the pilot signal pro~iding the J~rnchronization~ The UHF si~ then amplified ~y amplirler 242 for tran~mi~ion to RS~ ccll ~ite l~lO ~o~ Fi~c 1~.
Fi~ure 4 is a ~chematic diag~m of ~ tcmotc cQn~ncr 400 al a RSA
remote con~rerter site such a~ 16~163 ~of Fi~ute l)~ Remote con~erte~ 4 30 utilizes direct heterodyne circuitr~ ~nd thc ~1amc S~ atcllite frequencic~ a~ convener 200 (of Fi~ute 2~.
An cxcmplary mobile uni~ 4n I tt~miL~ U~IF *i~n~ la ~ecei~in~ anlenna 423. The si~nal is filteted by rPîtet ~3î ~d up mi~cd to uplink SHF a~ mhc~ ~3 using a common pha~é pro~ided by a 10 hl~l~ pil~ si~nal ~y me~c ot a pn~se ~5 lock loop ~. Ther~le-, the SHF si~n~ is filt~re~ ~ filtcr ~3' t~ confine the si~nal lo it~ ptedetennined frequency t;Ul~C. and 3mplificd ~y unplificr ~3S. The common phase pro~ided by t~e 10 MH~ pllot ~ c~rried hy t~lC amplific~i uplink SHF si~ns~l and is directed lo antenn3 ~ l ~ c~rculstor ~3~
W0 92/00636 7 2 Q g 8 0 ~ 2 For IJHF paging and transmitting infonnation, modulated satellite SHF
downlink signals are receh~ed at antenna 441, circulated to the parallel configuration of band pass filter (BPI:) 410 and mi~er 401. The downlink signal from satellite 130 can be meant for a remote conYener site or a RSA cell site (as shown in Figure 1), Which type of site is dete~mined by the predetermined choice of the UHF upper or lower side band. Tha~ is. if the upper side band is chosen for the transmission al the RSA cell sile. then the lower side band is used for the transmission at the ~note coo~rener site~
The Sl~; ~i~al from band-pass filter 410 is sdeaed by detector 450 o which is an envelope detector, The 10 MH~ pilot si~ iS recovered at node c and its upperband noise is redtlced by a low-pass filta 451 Phase-lock loop 445 pro~vides the satetlite downlink camet. which fr~ency is determined by the panicular satellite. Phæ-lock loop 444 pfovida the satellite uplink camer. By recovenng the 10 MHz signal. thac iS no ~t of a local oscillalot (such IS as 210 of Figure 2), the signals being ~mchroni~cd by the reco~/ered common 10 MHz pilot signal to a common phase al SHF for ~11 RSA remote con~enet si~
The SHF signal i~ down-cQn~ed n mi~a 402 via ph;~ie-lock loop ~45, f~lured b~ filur 433 and t~ansmitud by uu~ ing antenna 422 to mobile uni~
401, Figure S ~chematicallr ~ow~ p~sc-locl~ l~op ~44 which oper~u~ in ~e same fashion as ph~e-lock loop 212 of Fi~ute 3 w~tls ~JCO S10 opcratin~ a uplink SHF ftequencie~.
An alternadvc embadimcnl of ~ prcsent inllenuon is ~o odli~c ~
precision clock at the cell site to pto~ride uplinlt syncl~mni~ation of tne s~nals 2.S from the remote conve ter ~ites. This a~n bc ~d b~ lla~nn~ ~ clock pro~iding clock erron of subltanti~ oor k~ The clock req~irc~ an initial line-up ~et-up and a petiodic alignment chcck In i~ ptOpet ~i~nal synchroni~ation.
A telephone ~y~tem ~pically ba~ a Cenual l)ffice (C()) wbicl~ ~t~
the wirelincs for the lelephonel in the ~n:a ~ RS~ ~ould ba~e ~ucl~ a CO wit~in its area. Ir there is a CO in Ihæ RS~. tllen c311~ ~tom mobile units an~ l~aî
landline~ would be local calls~ tf t1~ ~11 Sl ) i~ l~csted in ~ Mettopolitan Stat~s~ical Area ~MSA) tar from ~e Ct~ ~ittlin lllc RS~ then the c311s f~om mobilc uniu to local 13ndlines may bccomc bn~ dis~ancc c~ . T~ ~oid thc 3S mobi1c call~ from bccomin~ lon~ di~nce call~ tnc communicalinn ~etwe~n the MTSO and Ihe CO cs~n be m~de ~ia tlle ~t~Uitc Imk~
Figurc 6 schcmalically show~ ~n 9 nn~ement accotding tn t~c p~ent in~/ention wheteby a satellite link between ~rrso ~nd cn is mlde. ~
WO 92/00636 ~ 8 pcr/us91/w3 exemplary home is connected by wireline 603 and C0 610 which in tum is connected by wireline 604 to a data bank 621 which is located at MTS0 620.
Data bank 621 performs the analog ~o digital and bit rate conversions required by MTSO 620, as are known in the communications a~ MTS0 620 is 5 communicatively coupled to RSA cell sites as shown in Figure 1. A MTS0 convener 623 communicates with satellile 130 v~a anteMa 622. MTS0 converter is a simple baseband up/down SHF con~erter which allo vs communications with satellite 130 for the purposes lin~ng ~S0 6~a with co 640. co 640 communicates with sa~lite 130 ~a antama 632 ~ich is connected to a C0 10 converter 634 which in turn is connected by a data bank 631.
The present in~ention has the fun~er ad~antage that for paging of the mobile units, only a single hop from the cell site up to the saullite then down to the mobile units is required. That is. util~ng a satellite a110ws a downlink page lO all converter sites simultaneously In land-based ceUular systems. multiple 1S hops using microwa~e backbone systems from cell site to cell site are typical1y required.
While the a~o~e description pro~rides a full and complete desc~ip~ion of Ihe preferred embodiments of the ptesent imention. vartous modificalions alurnau constmctjons and equi~ralents may be cmployed. For e~tample. lhe 20 present invention is not limited to so called l'Ut;~ serrice areas, t~Ut C~Uladvantageousl~r pro~ide adequate sennce ~o any ~i~tion where there sre fewer mobile u~ers, as in a le~s developed countr~ etefore. the above desc~pùon and illust ations should not be cons~ued as limi~in~ the scope of the in~enùon which is defined by the followin~ claim~
Claims (7)
1. A mobile communications system, utilizing at least one communications satellite and at least one mobile telephone switching office (MTSO), for communicating with a plurality of mobile units via said satellite, the system comprising: at least one cell site having a cell site converter thereat for converting signals from said satellite to signals for said MTSO and vice-versa, said cell site converter having an antenna for communicating with said satelliteand a MTSO communication means for communicating with said mobile telephone switching office; and at least one remote converter site each having at least one remote converter thereat for converting signals from said satellite tosignals for said mobile units, each of said remote converters including an antenna for communicating with said satellite, and a transmitter and a receiver for communicating with said mobile units.
2. The mobile communications system of claim 1 wherein said cell site converter and said remote converters communicate with said satellite over asingle satellite communications link.
3. The mobile communications system of claim 1 wherein said cell site is co-located with said mobile telephone switching office.
4. The mobile communications system of claim 1 wherein said cell site converter further comprises pilot signal generating means for generating a pilot signal, and said plurality of remote converters each further comprise pilot signal recovery means for recovering said pilot signal for frequency- and phase-synchronizing the communications from said remote converters to said satellite.
5. The mobile communications system of claim 1 wherein said cell site further comprises precision clock means for frequency- and phase-synchronizing the communications from said remote converters to said satellite.
6. The mobile communications system of claim 1 further utilizing at least one first wireline central office connecting landline telephones to said MTSO, and at least one second wireline central office connecting landline telephones to said remote cell site, the mobile communications system further comprising: a MTSO converter disposed at said MTSO for communicating with said satellite via a MTSO converter antenna; a first data bank means disposed atsaid MTSO and coupled between said first central office and said MTSO for converting communications from said first wireline central office for use in said MTSO and vice-versa; a remote CO converter disposed at said remote converter sites for communicating with said satellite via a remote DO converter antenna;
and a second data bank disposed at said remote converter sites and coupled between said remote CO converter and said second wireline central office for converting communications from said remote convener to said second wireline office and vice-versa.
and a second data bank disposed at said remote converter sites and coupled between said remote CO converter and said second wireline central office for converting communications from said remote convener to said second wireline office and vice-versa.
7. A mobile communications system, utilizing at least one communications satellite and at least one mobile telephone switching office, forcommunicating with a plurality of mobile units via said satellite, the system comprising: at least one cell site having a cell site converter thereat for converting signals from said satellite to signals for said MTSO and vice-versa, said cell site convener having an antenna for communicating with said satellite and a MTSO communication means for communicating with said mobile telephone switching office; at least one remote converter site each having at least one remote converter thereat for converting signals from said satellite to signals for said mobile units, each of said remote converters including an antenna for communicating with said satellite, and a transmitter and a receiver for communicating with said mobile units; said cell site converter and said remote converters further communicating with said satellite over a single satellite communications link; said cell site further being co-located with said mobile telephone switching office; and said cell site converter further comprising pilot signal generating means for generating a pilot signal, and said plurality of remote converters each further comprising pilot signal recovery means for recovering said pilot signal for frequency- and phase-synchronizing the communications from said remote converters to said satellite.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US544,607 | 1990-06-27 | ||
| US07/544,607 US5081703A (en) | 1990-06-27 | 1990-06-27 | Satellite mobile communication system for rural service areas |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2088052A1 true CA2088052A1 (en) | 1991-12-28 |
Family
ID=24172873
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002088052A Abandoned CA2088052A1 (en) | 1990-06-27 | 1991-06-13 | Satellite mobile communication system for rural service areas |
Country Status (4)
| Country | Link |
|---|---|
| US (1) | US5081703A (en) |
| EP (1) | EP0538322A4 (en) |
| CA (1) | CA2088052A1 (en) |
| WO (1) | WO1992000636A1 (en) |
Families Citing this family (96)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US5303286A (en) * | 1991-03-29 | 1994-04-12 | Space Systems/Loral, Inc. | Wireless telephone/satellite roaming system |
| US5239671A (en) * | 1990-11-13 | 1993-08-24 | Pagemart, Inc. | Simulcast satellite paging system with provision for signal interruption |
| CA2078932C (en) * | 1991-10-10 | 2003-12-02 | Robert A. Wiedeman | Satellite telecommunications system using network coordinating gateways operative with a terrestrial communication system |
| US5526404A (en) * | 1991-10-10 | 1996-06-11 | Space Systems/Loral, Inc. | Worldwide satellite telephone system and a network coordinating gateway for allocating satellite and terrestrial gateway resources |
| US8352400B2 (en) | 1991-12-23 | 2013-01-08 | Hoffberg Steven M | Adaptive pattern recognition based controller apparatus and method and human-factored interface therefore |
| US10361802B1 (en) | 1999-02-01 | 2019-07-23 | Blanding Hovenweep, Llc | Adaptive pattern recognition based control system and method |
| US5235633A (en) * | 1991-12-26 | 1993-08-10 | Everett Dennison | Cellular telephone system that uses position of a mobile unit to make call management decisions |
| US6324404B1 (en) * | 1991-12-26 | 2001-11-27 | Sycord Limited Partnership | Cellular telephone system that uses position of a mobile unit to make call management decisions |
| US5546445A (en) * | 1991-12-26 | 1996-08-13 | Dennison; Everett | Cellular telephone system that uses position of a mobile unit to make call management decisions |
| US5343512A (en) * | 1992-03-27 | 1994-08-30 | Motorola, Inc. | Call setup method for use with a network having mobile end users |
| US5394560A (en) * | 1992-09-30 | 1995-02-28 | Motorola, Inc. | Nationwide satellite message delivery system |
| FR2700649B1 (en) * | 1993-01-20 | 1995-04-07 | Dassault Electronique | Method and devices for transmitting information, in particular by satellite. |
| FR2703199B1 (en) * | 1993-03-26 | 1995-06-02 | Matra Communication | Radio transmission method using repeating spectrum inverting stations. |
| US5422647A (en) * | 1993-05-07 | 1995-06-06 | Space Systems/Loral, Inc. | Mobile communication satellite payload |
| JP2901170B2 (en) * | 1993-05-27 | 1999-06-07 | ケイディディ株式会社 | Satellite / land mobile communication system integration method |
| AU666279B2 (en) * | 1993-06-14 | 1996-02-01 | Motorola, Inc. | Cellular communication system having information retrieval and method therefor |
| CA2134395A1 (en) * | 1993-11-26 | 1995-05-27 | Keith Andrew Olds | Method and apparatus for management of automatically initiated communication |
| JPH07154859A (en) * | 1993-11-29 | 1995-06-16 | Mitsubishi Electric Corp | Mobile equipment, switchboard and mobile communication system |
| ATE197860T1 (en) | 1994-01-11 | 2000-12-15 | Ericsson Inc | POSITION RECORDING FOR SATELLITE CELLULAR COMMUNICATION ARRANGEMENTS |
| US5907809A (en) * | 1994-01-11 | 1999-05-25 | Ericsson Inc. | Position determination using multiple base station signals |
| US6868270B2 (en) | 1994-01-11 | 2005-03-15 | Telefonaktiebolaget L.M. Ericsson | Dual-mode methods, systems, and terminals providing reduced mobile terminal registrations |
| US6195555B1 (en) | 1994-01-11 | 2001-02-27 | Ericsson Inc. | Method of directing a call to a mobile telephone in a dual mode cellular satellite communication network |
| US5859874A (en) * | 1994-05-09 | 1999-01-12 | Globalstar L.P. | Multipath communication system optimizer |
| US5758287A (en) * | 1994-05-20 | 1998-05-26 | Airtouch Communications, Inc. | Hub and remote cellular telephone system |
| US6400926B1 (en) * | 1994-06-22 | 2002-06-04 | Ericsson Ge Mobile Communications Inc. | Radiocommunication system using geostationary and non-geostationary satellites |
| US5519760A (en) * | 1994-06-22 | 1996-05-21 | Gte Laboratories Incorporated | Cellular network-based location system |
| US5787336A (en) * | 1994-11-08 | 1998-07-28 | Space Systems/Loral, Inc. | Satellite communication power management system |
| US5867765A (en) * | 1995-03-31 | 1999-02-02 | Telefonaktiebolaget Lm Ericsson | Non-geostationary satellite mobile communication system integration with network principles for terrestrial cellular |
| US5619525A (en) * | 1995-06-06 | 1997-04-08 | Globalstar L.P. | Closed loop power control for low earth orbit satellite communications system |
| US5592481A (en) * | 1995-06-06 | 1997-01-07 | Globalstar L.P. | Multiple satellite repeater capacity loading with multiple spread spectrum gateway antennas |
| US5634190A (en) * | 1995-06-06 | 1997-05-27 | Globalstar L.P. | Low earth orbit communication satellite gateway-to-gateway relay system |
| US6240124B1 (en) | 1995-06-06 | 2001-05-29 | Globalstar L.P. | Closed loop power control for low earth orbit satellite communications system |
| BR9608410A (en) | 1995-06-06 | 1998-12-29 | Globalstar Lp | Repeater satellite diversity resource management system |
| US5640386A (en) * | 1995-06-06 | 1997-06-17 | Globalstar L.P. | Two-system protocol conversion transceiver repeater |
| US5664006A (en) * | 1995-06-07 | 1997-09-02 | Globalstar L.P. | Method for accounting for user terminal connection to a satellite communications system |
| EP0750406A3 (en) * | 1995-06-19 | 2002-01-02 | Ntt Mobile Communications Network Inc. | Satellite and terrestrial cellular integrated mobile communication system |
| NL1000628C2 (en) * | 1995-06-22 | 1996-12-24 | Nederland Ptt | Earth station system comprising a first and a second earth station, as well as a earth station, as well as a device and method. |
| US6272325B1 (en) | 1995-07-13 | 2001-08-07 | Globalstar L.P. | Method and apparatus for considering user terminal transmitted power during operation in a plurality of different communication systems |
| US5802445A (en) * | 1995-07-13 | 1998-09-01 | Globalstar L.P. | Methods and apparatus for providing user RF exposure monitoring and control in a satellite communications system |
| DE69631227T2 (en) * | 1995-07-20 | 2004-11-18 | Ntt Docomo Inc. | Efficient service area expansion scheme for mobile transmission system |
| US5758260A (en) * | 1995-08-23 | 1998-05-26 | Globalstar L.P. | Satellite beam steering reference using terrestrial beam steering terminals |
| US6272316B1 (en) | 1995-11-17 | 2001-08-07 | Globalstar L.P. | Mobile satellite user information request system and methods |
| US5812932A (en) * | 1995-11-17 | 1998-09-22 | Globalstar L.P. | Mobile satellite user information request system and methods |
| JP3633707B2 (en) * | 1996-03-08 | 2005-03-30 | 日産ディーゼル工業株式会社 | Vehicle group running control device |
| US5930708A (en) * | 1996-03-21 | 1999-07-27 | Trw Inc. | Communications satellite router-formatter |
| US6035178A (en) * | 1996-05-09 | 2000-03-07 | Ericsson Inc. | Satellite communication system for local-area coverage |
| US6067452A (en) * | 1996-05-28 | 2000-05-23 | Comsat Corporation | Technique for least cost routing for mobile satellite systems employing a GSM network infrastructure |
| US6072768A (en) | 1996-09-04 | 2000-06-06 | Globalstar L.P. | Automatic satellite/terrestrial mobile terminal roaming system and method |
| US6201961B1 (en) | 1996-09-13 | 2001-03-13 | Globalstar L. P. | Use of reference phone in point-to-point satellite communication system |
| FR2753589B1 (en) * | 1996-09-17 | 1998-10-09 | Alcatel Espace | RELAYS FOR RADIOCOMMUNICATION SYSTEM |
| US6587687B1 (en) | 1996-10-21 | 2003-07-01 | Globalstar L.P. | Multiple satellite fade attenuation control system |
| US5956619A (en) * | 1996-12-12 | 1999-09-21 | Globalstar L.P. | Satellite controlled power control for personal communication user terminals |
| US5896558A (en) * | 1996-12-19 | 1999-04-20 | Globalstar L.P. | Interactive fixed and mobile satellite network |
| DE19653469C2 (en) * | 1996-12-20 | 1998-12-03 | Siemens Ag | Method for controlling the connection between a communication terminal of a radio communication network and a further communication terminal and a corresponding radio communication system |
| US5875180A (en) * | 1997-02-06 | 1999-02-23 | Globalstar L.P. | Satellite telephone interference avoidance system |
| US5918157A (en) * | 1997-03-18 | 1999-06-29 | Globalstar L.P. | Satellite communications system having distributed user assignment and resource assignment with terrestrial gateways |
| US5884142A (en) * | 1997-04-15 | 1999-03-16 | Globalstar L.P. | Low earth orbit distributed gateway communication system |
| US6128487A (en) | 1997-04-15 | 2000-10-03 | Globalstar, L.P. | Global mobile paging system |
| US6064857A (en) * | 1997-04-15 | 2000-05-16 | Globalstar L.P. | Dual mode satellite telephone with hybrid battery/capacitor power supply |
| US5905943A (en) * | 1997-04-29 | 1999-05-18 | Globalstar L.P. | System for generating and using global radio frequency maps |
| US6021309A (en) * | 1997-05-22 | 2000-02-01 | Globalstar L.P. | Channel frequency allocation for multiple-satellite communication network |
| US6081710A (en) * | 1997-07-10 | 2000-06-27 | Globalstar L.P. | Dynamic traffic allocation for power control in multiple satellite communication systems |
| US6484012B1 (en) * | 1997-08-04 | 2002-11-19 | Wireless Facilities, Inc. | Inter-band communication repeater system |
| FR2767244B1 (en) | 1997-08-11 | 2004-09-24 | Te Sa M Telecomm Par Satellite | DEVICE FOR CONNECTING A TELEPHONE SWITCH TO A TELEPHONE NETWORK FIXED VIA A RADIOTELEPHONE NETWORK |
| US6243577B1 (en) * | 1997-08-15 | 2001-06-05 | Hewlett-Packard Corporation | Frequency translation to local multi-point distribution system for personal communications services |
| US6101385A (en) | 1997-10-09 | 2000-08-08 | Globalstar L.P. | Satellite communication service with non-congruent sub-beam coverage |
| WO1999026358A1 (en) * | 1997-11-14 | 1999-05-27 | Comsat Corporation | Architecture for integrated wll/vsat system |
| BR9706310A (en) * | 1997-12-22 | 1999-07-20 | De Andrade Erick Serg Schimidt | Road radio cellular service system |
| US6294583B1 (en) * | 1998-01-13 | 2001-09-25 | Synchroneuron, Llc | Methods of treating tardive dyskinesia and other movement disorders |
| US6418147B1 (en) * | 1998-01-21 | 2002-07-09 | Globalstar Lp | Multiple vocoder mobile satellite telephone system |
| DE19812916A1 (en) * | 1998-03-24 | 1999-10-14 | Siemens Ag | Method and radio communication system for connection control for calls from / to radio subscribers |
| US6944139B1 (en) * | 1998-03-27 | 2005-09-13 | Worldspace Management Corporation | Digital broadcast system using satellite direct broadcast and terrestrial repeater |
| US6657978B1 (en) * | 1998-04-23 | 2003-12-02 | Transworld Communications (Usa), Inc. | Optimized integrated high capacity digital satellite trunking network |
| US6591084B1 (en) * | 1998-04-27 | 2003-07-08 | General Dynamics Decision Systems, Inc. | Satellite based data transfer and delivery system |
| US6661996B1 (en) | 1998-07-14 | 2003-12-09 | Globalstar L.P. | Satellite communication system providing multi-gateway diversity to a mobile user terminal |
| US7966078B2 (en) | 1999-02-01 | 2011-06-21 | Steven Hoffberg | Network media appliance system and method |
| US6253080B1 (en) | 1999-07-08 | 2001-06-26 | Globalstar L.P. | Low earth orbit distributed gateway communication system |
| US6477369B1 (en) * | 1999-09-30 | 2002-11-05 | Adc Telecommunications, Inc. | Broadband communication network |
| US6463279B1 (en) | 1999-11-17 | 2002-10-08 | Globalstar L.P. | Channel frequency allocation for multiple-satellite communication network |
| CA2381811C (en) | 2000-08-02 | 2007-01-30 | Mobile Satellite Ventures Lp | Coordinated satellite-terrestrial frequency reuse |
| US6859652B2 (en) | 2000-08-02 | 2005-02-22 | Mobile Satellite Ventures, Lp | Integrated or autonomous system and method of satellite-terrestrial frequency reuse using signal attenuation and/or blockage, dynamic assignment of frequencies and/or hysteresis |
| JP2002057609A (en) * | 2000-08-10 | 2002-02-22 | Honda Motor Co Ltd | Mobile satellite communication system |
| US7107075B2 (en) * | 2000-08-25 | 2006-09-12 | Bellsouth Intellectual Property Corporation | Wireless communications methods and systems using a remote, self-contained communications antenna unit |
| US7792488B2 (en) * | 2000-12-04 | 2010-09-07 | Atc Technologies, Llc | Systems and methods for transmitting electromagnetic energy over a wireless channel having sufficiently weak measured signal strength |
| US6807158B2 (en) | 2001-08-07 | 2004-10-19 | Hrl Laboratories, Llc | Method and apparatus for determining position and trajectory of gateways to optimize performance in hybrid non-terrestrial-terrestrial multi-hop mobile networks |
| US7664460B2 (en) * | 2001-09-14 | 2010-02-16 | Atc Technologies, Llc | Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex and/or frequency-division duplex mode |
| US7593724B2 (en) * | 2001-09-14 | 2009-09-22 | Atc Technologies, Llc | Systems and methods for terrestrial reuse of cellular satellite frequency spectrum in a time-division duplex mode |
| US7366492B1 (en) | 2002-05-03 | 2008-04-29 | Verizon Corporate Services Group Inc. | Method and system for mobile location detection using handoff information |
| US7203490B2 (en) * | 2003-03-24 | 2007-04-10 | Atc Technologies, Llc | Satellite assisted push-to-send radioterminal systems and methods |
| CA2423896A1 (en) * | 2003-03-28 | 2004-09-28 | Norsat International Inc. | Highly integrated and compact baseband apparatus for portable newsgathering |
| CA2424025A1 (en) * | 2003-03-28 | 2004-09-28 | Norsat International Inc. | Integrated high frequency apparatus for the transmission and reception of signals by terminals in wireless communications systems |
| US7324469B2 (en) * | 2003-09-29 | 2008-01-29 | System Services, Inc. | Satellite distributed high speed internet access |
| US7821984B2 (en) * | 2003-09-29 | 2010-10-26 | Wilson W David | Satellite distributed high speed internet access |
| US8655398B2 (en) | 2004-03-08 | 2014-02-18 | Atc Technologies, Llc | Communications systems and methods including emission detection |
| US7659708B2 (en) * | 2005-08-24 | 2010-02-09 | Nucomm, Inc. | Broadcast receiver having integrated spectrum analysis |
| US8300798B1 (en) | 2006-04-03 | 2012-10-30 | Wai Wu | Intelligent communication routing system and method |
Family Cites Families (13)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4273962A (en) * | 1978-08-29 | 1981-06-16 | Harris Corporation | Impulse metering of local telephone switching offices via a DAMA DOMSAT communication system |
| US4506383A (en) * | 1980-01-04 | 1985-03-19 | Harris Corporation | Method and apparatus for relaying signals between a ground station and a satellite using a ground relay station |
| US4479256A (en) * | 1982-10-04 | 1984-10-23 | Ael Microtel, Limited | Two pilot frequency control for communication systems |
| JPS59147549A (en) * | 1983-02-10 | 1984-08-23 | Fujitsu Ltd | Direct repeater |
| DE3313840A1 (en) * | 1983-04-16 | 1984-10-18 | Standard Elektrik Lorenz Ag, 7000 Stuttgart | Data transmission system with time division multiple access (TDMA) with locally synchronised access |
| EP0137865A1 (en) * | 1983-10-15 | 1985-04-24 | ANT Nachrichtentechnik GmbH | Method of setting up a radio communication |
| EP0144665B1 (en) * | 1983-12-08 | 1988-05-25 | ANT Nachrichtentechnik GmbH | Method and system for establishing a telephone connection with a mobile suscriber |
| IT1209566B (en) * | 1984-07-06 | 1989-08-30 | Face Standard Ind | SYSTEM AND PROCEDURE TO IDENTIFY THE POSITION OF A RADIO USER WITHIN A WIDE GEOGRAPHICAL SURFACE. |
| US4849963A (en) * | 1985-10-15 | 1989-07-18 | Minori Kawano | Cellular radio telephone enhancement circuit |
| US4704733A (en) * | 1985-12-16 | 1987-11-03 | Minoru Kawano | Cell enhancer for cellular radio telephone system having diversity function |
| DE3605049A1 (en) * | 1986-02-18 | 1987-08-27 | Ant Nachrichtentech | ARRANGEMENT FOR A TRANSMISSION NETWORK |
| US5101500A (en) * | 1988-05-30 | 1992-03-31 | Kabushiki Kaisha Toshiba | Radio telecommunication apparatus |
| IL91529A0 (en) * | 1988-10-28 | 1990-04-29 | Motorola Inc | Satellite cellular telephone and data communication system |
-
1990
- 1990-06-27 US US07/544,607 patent/US5081703A/en not_active Expired - Lifetime
-
1991
- 1991-06-13 EP EP19910912642 patent/EP0538322A4/en not_active Withdrawn
- 1991-06-13 WO PCT/US1991/004301 patent/WO1992000636A1/en not_active Application Discontinuation
- 1991-06-13 CA CA002088052A patent/CA2088052A1/en not_active Abandoned
Also Published As
| Publication number | Publication date |
|---|---|
| EP0538322A4 (en) | 1993-12-01 |
| EP0538322A1 (en) | 1993-04-28 |
| US5081703A (en) | 1992-01-14 |
| WO1992000636A1 (en) | 1992-01-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| CA2088052A1 (en) | Satellite mobile communication system for rural service areas | |
| US4337376A (en) | Communications system and network | |
| US6404775B1 (en) | Band-changing repeater with protocol or format conversion | |
| EP1121771B1 (en) | Method for use in a dual mode satellite communications network | |
| US5884142A (en) | Low earth orbit distributed gateway communication system | |
| CA1271548A (en) | Distributed switching architecture | |
| US9698896B2 (en) | Multiple access spread spectrum switching methodology | |
| CA2108459A1 (en) | Fully meshed cdma network for personal communications terminals | |
| Puente et al. | Multiple-access techniques for commercial satellites | |
| KR100700757B1 (en) | Method for deep paging | |
| RU2133555C1 (en) | Method and device for high- and low-speed communications through low- and medium-orbit satellites | |
| JPS6062739A (en) | Satellite mounting device | |
| CN1092875C (en) | Method and apparatus for mobile station-to-mobile station calls in a mobile satellite communications system with on-board TDMA formot conversion | |
| JPS58186236A (en) | Multi-dimensional connecting system for satellite communication | |
| KR100264358B1 (en) | A cdma repeater for compressing the bandwidth of signal to be repeated and its processing method | |
| Bartholome | Digital satellite networks in Europe | |
| Wittig et al. | OBP for private networks and residential users | |
| Masamura et al. | Satellite communication system using TDM and SSMA | |
| AU2004203066B2 (en) | Method for deep paging | |
| MANNING et al. | ACTS T1-VSAT-The intelligent earth station | |
| Rao | VSATs for rural telecommunications | |
| Wittig et al. | On-board processing for private networks | |
| Salivahanan et al. | Cellular Mobile Telephony-A Spread Spectrum Approach | |
| Schmeller | The German telecommunications satellite system DFS-Kopernikus | |
| NZ200569A (en) | Cellular radio frequency division multiplex communications system |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| FZDE | Discontinued |