Tong quan C

8/3/2019 Tong quan C

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Chng 1GII THIU TNG QUAN H THNG INMARSAT-C

1. Gii thiu v h thng v cc dch v trong INMARSAT-C

1.1.H thng INMARSAT-CH thng INMARSAT-C chnh thc c a vo s dng t thng 1

nm 1991 (bt buc vi cc tu c trng ti 5000 tn tr ln) v tip tcc hon thin t . Vic thng tin trong h thng cng dng cc v tinhINMARSAT. l h thng thng tin s cho dch v truyn ch v s liuc cu trc cng gm c i phi hp h thng NCS cho mi vng ph sngca v tinh, cc i b LES v cc i di ng MES.

H thng INMARSAT-C c u im ln l thit b c gi thnh thp, sdng anten v hng nh gn nn rt ph hp cho vic lp t thit b trnnhng phng tin nh nhng nhc im ca n l khng c phng thcthng tin thoi.H thng INM-C l h thng s hon ton, cung cp dch v telex, data giatrm di ng MES (Mobile Earth Station) v trm mt t c nh LES(Land Earth Station) c ni vi mng thng tin mt t. Thng tin cth c thc hin gia hai trm di ng vi nhau thng qua LES. Trm ding c lp t trn tu, trn t lin hay trn cc phng tin vnchuyn.

1.2. Cc dch v trong INMARSAT-C

1.2.1/ Thng tin thng thngDch v ny cung cp mt phng thc tin cy chuyn cc vn bn

hoc d liu gia thu bao ca mng mt t v cc i di ng cng nhgia cc i di ng vi nhau. Khi mt i MES pht bc in ca mnhdi dng cc gi tin ti mt i LES, i LES s kt hp li cc gi tintrc khi chuyn tip chng ti ch, thng tin ti thu bao c th bng

telex, fax, data hoc email tu theo yu cu ca MES. m bo bc inthu c ton vn mi gi tin u c kim tra li v yu cu pht li khic li, ch khi bc in c thu y v khng c li th n mi cchuyn tip ti ch.

1.2.2/ Gi cp cu:


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Thut ng "Gi cp cu " bao hm cc cuc bo ng cp cu v ccbc in vi mc u tin cp cu. Khi nhn c cuc gi bo ng cpcu LES phi ngay lp tc xc nhn v chuyn tip bo ng ti RCC (trungtm cu nn) quc t hoc quc gia. Ni dung bo ng cp cu thnggm v tr v thi gian c cp nht sm nht ca MES.

1.2.3/ Gi nhm tng cng EGCDch v gi nhm tng cng l dch v pht thng tin qung b ca

h thng INM-C. Cc bc in EGC c chuyn ti LES qua mng mt tbng telex, email... sau LES s tin hnh x l v chuyn tip bc inti NCS. NCS s xp xp thi gian pht bc in EGC ti ton b vng binm n ph trch trn knh bo hiu chung. Bc in EGC c th chuyn timt i tu, mt nhm i tu, a ch theo vng a l (hnh vung, hnhtrn) hoc a ch theo vng NAVAREA.

Dch v EGC gm hai dch v con : Fleet Net: Cung cp thng tin thng mi cho mt thu bao nht nh

hoc mt nhm thu bao (vd : mt cng ty vi i tu ca n). Safety Net: Cung cp thng tin an ton hng hi MSI bao gm : cnh

bo hng hi, d bo kh tng thi tit v cc thng tin an ton khc.

1.2.4/ Thng bo d liu (data report)Dch v ny cho php cc cng ty hoc chnh ph thu thp cc d liu

lin quan ti i tu ca h nh v tr, tnh trng tu, thi tit... c th

a ra cc quyt nh tr gip hp l nht l khi tu gp nn hoc c nguyc m va. Cc d liu v tu c th c chuyn trc tip ti thit b ucui INM-C t cc thit b hng hi v cc b cm bin gn trn tu .

1.2.5/ PollingPolling l dch v c s dng cho mc ch xng vic thng

bo d liu t MES. Cc i ny pht cc lnh thm d ti MES ch dncch thc v thi gian pht, lnh thm d cng c th yu cu c xc nhn

bi MES.C ba kiu thm d khc nhau :

Thm d tng i MES nht nh: Khi mt thu bao mt t c yucu thm d, n s gi mt danh sch cc i MES cn thm d tii LES qua mng mt t, sau i LES s pht cc tn hiu thmd ring r ti tng MES, nu MES bn th tn hiu thm d s ch

pht li khi MES ri.


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Thm d mt nhm MES : NCS s pht mt tn hiu thm d duynht trn knh bo hiu chung ti mt nhm MES, vic pht c thlp li nu khng nhn c tr li.

Thm d theo khu vc : Cng ging nh thm d theo nhm nhng

cc i MES thuc mt khu vc a l c nh ngha trong ni dungbc in thm d.

1.3. Cu trc h thng INMARSAT-C

1.3.1. Kin trc v cc thnh phn trong INM-CTrong s sau s ch ra cc thnh phn trong kin trc h thng

INMARSAT-C gm c: LES, NOC, NCS v MES.

1.3.2./ Trung tm iu hnh mng - NOC (Network Operrators Centre)Thc hin chc nng qun l mng nh cp nhn dng cho cc i di

ng mi v chuyn thng tin ny vo bng danh sch cc i di ng caNCS. Ngoi ra n cn thc hin loan bo khi c s xut hin ca mt LESmi. Lin lc gia NOC vi NCS c thc hin qua mng thng tin mtt.


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1.3.4./ Trm phi hp mng - NCS (Network Coordination Station)

Mi mt i dng s c mt NSC qun l, iu khin tt c thng tin

lin lc trong vng bin . Tri t c chia lm bn vng do 4 NCS qunl nh sau: AORE NCS t ti Anh (i Goonhilly) AORW NCS t ti Nauy (i Eik) IOR NCS t ti Singapore (i Sentosa) POR NCS t ti Nht (i Yamaguchi)

Cc chc nng chnh ca NCS gm c: Kt ni ti cc NCS khc qua trung tm iu hnh mng.

Pht cc bc in EGC ti cc tu nm trong vng bin m n qunl. Loan bo mt cuc gi. Xc nhn in.

Tt c cc MES hot ng trong vng bin do NCS ph trch u c yucu ng nhp vo mng, mt danh sch ca tt c cc MES ng k sc NCS gi ti LES gip LES khi cn chuyn cuc gi ti MES t

NOC

AORE

NCS-2

POR

NCS-2

AORW

NCS-2

IOR

NCS-2

LES LES LES LES LES LES

LES LES LES LES LES LES


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mt thu bao trong mng mt t. Trm NCS cn thc hin vic gim stcc MES m bo rng khi MES di chuyn t vng bin ny sang vng

bin khc th cuc gi ti MES s c pht li hoc hu b.1.3.5../ Trm mt t LES (Land Earth Station)

Chc nng chnh ca LES l nh tuyn cc bc in gia mng vtinh v mng mt t. Ngoi ra mi mt trm LES (nh mt Gateway) lmnhim v kt ni thng tin gia v tinh v mng thng tin cng cng qucgia hoc quc t. Mi nc c th lp t mt trm LES nhm lm gim phtn khi lin lc qua mng mt t, iu ny ngha l mi vng bin c nhiutrm LES. Trm LES c h thng Anten ln c th lin lc vi v tinh tngng trong vng ph sng, cho php kt ni ng thi vi nhiu trm di ngMES. Ch iu hnh trm LES thng l nhng cng ty vin thng ln m

bo cung cp dch v trn vng rt rng cho cc trm thng tin di ngMES.

Mi LES trong khu vc do NCS qun l s kt ni vi NCS qua knh bohiu lin i ISL (Interstation Signalling Link).

1.3.6./ Trm di ng mt t MES (Mobile Earth Station)Mi MES bao gm hai phn: mt phn thc hin chc nng giao tip

ngi my l mt my vi tnh cn c gi l DTE (data terminalequipment), mt phn thc hin chc nng truyn d liu gia DTE v ccthit b ngoi vi, v tinh c gi l DCE (data circuit terminal equipment).Trm MES l thit b c lp trn cc phng tin di ng hoc nhng

ni xa xi ho lnh c th thng tin lin lc vi cc thu bao b qua hthng thng tin INMARSAT. Cc trm MES thng c kt cu nh gn vc chc nng ph hp vi tng yu cu s dng nhm m bo gi thnhthp ph hp cho mi i tng s dng.

1.4. Thng tin trong h thng INMARSAT-CS ch ra cc bng tn v cc knh dng trong thng tin gia LES -

MES, LES - NCS thng qua v tinh (Hnh 1).

Mc ch chnh trong thng tin INMARSAT-C l thc hin kt ni trm di

ng vi mng thng tin mt t chuyn cc bc in telex, EGC, cpcu

Forward Link (ng ln): thc hin kt ni thng tin gia v tinh viNCS v LES. NCS v LES pht tn hiu ln v tinh trn bng C.

Return Link (ng xung): thc hin kt ni thng tin gia v tinhvi MES, MES nhn tn hiu t NSC v LES qua knh TDM c tn


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s sng mang thuc bng L, cc bc in v burst tn hiu c MESpht i cng trn bng L.

1.4.1. c im chung ca cc knh thng tin trong h thng INM-C

1. iu ch: Cc knh thng tin trong h thng INM-C s dng iuch s BPSK 1200 symbol/s (v tinh th h 2) hoc 600 symbol/s (vtinh th h 1).

2. Tc thng tin: Mi knh thng tin c tc bt (trc khi mho v iu ch) l 600b/s(v tinh th h 2) hoc 300b/s (v tinh thh 1).

3. M ha: Mi loi knh thng tin khc nhau c th c x l mho trn hoc chn .- Knh TDM : 1/2 FEC v x l trn, chn.


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- Knh chuyn in: 1/2 FEC v x l trn, chn.- Knh bo hiu: 1/2 FEC v x l trn.

4. Bng tn thu pht : Cc knh thng tin u c thu pht bngC, v ch thu bng L

1.4.2. Phn loi knh thng tin(S knh thng tin v cc gi tin dng trong tng knh c ch ra trongHnh 2)

1.4.2.1./ Knh bo hiu chung NCS (NCS Common Channel)Knh bo hiu chung NCS l mt knh TDM vi chiu di khung

8.64(s), iu ch 1200 sysbol/s, trn mi mt khung phn u bao gi cngl gi tin Bulletin Board n mang theo thng tin lin quan n knh TDM v

hot ng ca h thng. Knh ny c pht lin tc ti tt c cc i MEStrong khu vc bin ph trch ca NCS n mang theo cc thng tin v hthng, thng tin bo hiu v cc bc in EGC t NCS ti MES. MES s tng iu chnh ti knh bo hiu NCS thch hp khi n tnh trng ri,vic trc canh trn knh ny l bt buc i vi tt cc cc MES tr trnghp ang chuyn in.Mt i NCS c th pht mt hoc nhiu knh bo hiu chung tu thuc volu lng thng tin. Vic truy nhp ti knh bo hiu chung ca NCS theo

phng thc ti trc phc v trc cho cc gi c cng mc u tin.

Chc nng ca knh bo hiu knh chung NCS gm c: Loan bo bc in ti MES Xc nhn in t MES Lnh thm d (Polling commands) Chun thi gian cho cc i di ng. Pht cc bc in gi nhm tng cng (EGC) cho MES. Thng bo cho cc i di ng v trng thi thng thng ca mng

hoc trng thi thay i ca mng


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1.4.2.2./ Knh TDM ca LES

Knh LES TDM c cng cu trc nh knh bo hiu chung ca NCS.Mi i LES c t nht mt knh chung TDM, knh ny pht thng tin bohiu v chuyn tip cc bc in t LES ti MES. Vic truy nhp ti knhTDM ca LES theo phng thc ti trc phc v trc (first come - firstserved) i vi cc gi tin c cng mc u tin.C 4 mc u tin khi truy nhp vo knh theo th t nh sau:

in cp cu ng k knh thng tin Cc th tc khc Bc in thng thng

Knh TDM do NCS cp cho LES dng cho vic thit lp lin lc viMES c chia lm hai loi:

Hnh 2


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Knh c nh (Permanent) c LES pht lin tc khng gin onngay c trong khong thi gian khng lin lc.

Knh cp pht theo yu cu (Demand Assigned) ch dng trong chochu k thi gian lin lc do NCS cp khi LES c yu cu.

Vic s dng knh c nh hay knh cp pht l da ch yu vo kinh t vchnh sch ca quc gia c i LES. Knh TDM c nh thng dng chyu cho cc i LES c lu lng thng tin qua n cao, khi cn lin lc vimt i LES c knh TDM c nh MES s thu ngay knh LES TDM mkhng cn phi thu knh NCS TDM. Cn vi knh cp pht do ch s dngtrong thi gian c lin lc do i LES s tit kim c ti a chi ph

phi tr cho vic thu knh, v khi MES cn lin lc vi LES n phi thchin thng qua knh NCS TDM.

S khc nhau gia knh TDM c nh v knh TDM cp theo yu cu: Knh TDM c nh: i LES lun pht tn hiu trn mt nhm knh

(pool of channels) TDM c nh cp cho n, nhm knh TDM nygm c mt knh TDM kt hp vi vi knh bo hiu v knh chuynin. Trong trng hp LES ngng hot ng n phi tr li knhTDM ny, s thay i ny s c NOC x l v thng bo trong giBullentin board pht trn knh NCS TDM.

Knh TDM cp pht theo yu cu: Khi i LES hot ng ch

demand assigned th vic khi xng n nh knh TDM c thchin bi LES. trong trng hp NCS chp nhn yu cu cp knhTDM ca LES, n s cp cho LES mt knh TDM kt hp vi mtknh bo hiu v mt knh chuyn in. Knh TDM cp pht theoyu cu c NCS cp cho LES ch trong cc chu k thi gian cnh gi l Hold Time, v LES thc hin lin lc ch trong khongthi gian gi knh ny. Nu lin lc c thc hin xong trc khi ktthc khong thi gian ny th knh TDM s c tr li. Cn nukhong thi gian kt thc m lin lc cha thc hin xong th LESc th gi li knh TDM thc hin xong lin lc, nhng n khngc dng knh TDM thc hin cho cuc lin lc tip theo.

1. Nhng knh no c gi l knh TDM2. a ra c u nhc im ca hai ch knh ny3. Ch thch bng ting Anh tn cc knh1.4.2.3./ Knh bo hiu MES (Signalling channel)


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MES s s dng knh bo hiu c kt hp vi knh LES TDMhoc knh NCS TDM thit lp cuc gi ti LES, cc th tc ho mng(login) ra khi mng (logout) ti NCS hoc chuyn cc cuc bo ng cpcu ti c LES v NCS . Vic truy nhp ti knh bo hiu s dng phngthc truy nhp nhu nhin theo khe thi gian ng k.

1.4.2.4./ Knh chuyn in (Message channel)Knh ny c s dng chuyn cc bc in thng thng t MES

ti LES. Vic truy nhp ti knh ny da trn phng thc TDMA theo siu khin ca LES. Khi i MES nhn c gi tin n inh knh logic ns pht ton b bc in ca mnh khng gin on trn knh chuyn in.Cc i NCS s n nh mt hoc nhiu knh chuyn in cho LES tu theoch hot ng ca LES l n nh knh TDM hay cp knh TDM theoyu cu.

1.4.2.5./ Knh bo hiu lin i (Inter station link)LES s dng cc knh bo hiu lin i (ISL) trn ng truyn v

tinh gi cc thng tin bo hiu, cc bc in EGC hoc thng tin xng cuc gi ti NCS. NCS cng dng cc knh ny chuyn cc thngtin h thng v cc thng tin lin quan ti cuc gi ti LES.Cc i NCS thuc cc vng bin khc nhau c th dng cc knh bo hiutrong mng thng tin mt t trao i cc thng tin lin quan ti cc iMES hoc kt ni cc i NCS vi trung tm khai thc mng NOC

London.Knh ISL gia NCS-NCS: cho php NCS trao i thng tin hin ti v MESang khu vc qun l ca NCS no. Tuyn ni ny l t ng thc hintrn mng chuyn mch cng cng (PSTN) c tc 600bit/s s dngmodem song cng theo chun CCITT V.22Knh ISL gia NCS-LES: tt c cc i LES cung cp dch v INMARSAT-C u c knh ny, n c s dng trong giai on u tin tn hiu t LESchuyn n NCS pht i trn knh bo hiu knh chung ca NCS. Cc

bo hiu cp cu nhn c t NCS cng c gi n LES trn knh nyNgoi ra knh ny cn c s dng chuyn nhng thng tin v mng

gia NCS v LES iu ny cho php NCS qun l cc knh thng tin cngnh tnh trng ca mng


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Chng 2.Th Tc Lin Lc

Da trn nhng kin thc chung v phng thc lin lc, cc knh thngtin v cc gi tin. Chc nng ca NCS, LES v MES trong h thng

INMARSAT-C c trnh by trong cc chng trc. Chng ny stm him c th th tc lin lc c thit lp nh th no trong sut qutrnh lin lc theo chiu t LES n MES v t MES n LES.

2.1 Th tc lin lc LES - MES

2.1.1. Xt trng hp LES c knh TDM c nh

(S qu trnh lin lc LES - MES trng hp LES c knh TDM c nhc ch ra trong Hnh 4)Khi i di ng hnh trnh trn bin n phi thc hin vic trc canh trnknh bo hiu knh chung ca NCS m n ang hot ng.Khi LES nhn c in t mt thu bao c nh trong mng mt t hoct mt i i ng gi cho MES. LES s kim tra tnh trng ca MES trongLES DataBase v lu li bc in (bc in ny phi c ID + vng bin mtu ang hot ng) v lm cc th tc trc khi tin hnh pht bc in n MES nh sau:

1/ Kim tra trng thi ca MES bng vic pht gi tin Status Request tiNCS trn knh bo hiu knh chung (ISL). Vic kim tra ny nhm mcich xc nh tnh hp l ca MES (MES s b t chi dch v trong trnghp n khng ng cuc hoc b cm v bt c l do g), ngoi ra n cn xcnh trng thi hin thi ca MES l ang ri hay ang thc hin vicchuyn in.

2/ Sau khi NCS kim tra cc thng tin v MES, n s pht gi tin tr litrng thi ca MES (MES status) ti LES trn knh ISL.

Trong trng hp MES bn (ang tin hnh chuyn in) NCS s pht thngtin v MES ti LES v bo rng tin hnh ch ti khi MES ri. Khi NCSnhn c thng tin t mt LES khc thng bo MES ri th n lp tc s

pht tnh trng ca MES ti LES cn chuyn in.

3/ Loan bo cuc gi (Announcement)


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Gi s MES trng thi ri, NCS s pht loan bo ti MES ngay trnknh NCS TDM. Khi MES thu c loan bo cui gi, n bit rng ang cin cn gi t LES do n iu chnh tn s thu ti knh TDM ca LES.Thng tin v knh TDM ca LES c cha trong gi Bulletin board v gim t knh bo hiu. MES s chn ra mt khe thi gian ngu nhin chac dng ca knh bo hiu v pht tn hiu tr li loan bo (assignmentresponse). Nc ny MES sn sng cho vic nhn in.

4/ Tr li loan boGi tin tr li loan bo gm c s nhn dng ca MES v knh logic,

iu ny nhm bo cho LES bit MES chuyn v knh LES TDM v snsng cho vic nhn in.

5/ Bo trng thi ca MES

LES s bo trng thi bn ca MES ti NCS gip cho n cp nhn thng tinhin thi ca MES.

6/ Chuyn inLES s thc hin vic chuyn in ti MES trn knh TDM, bc in

s c chia thnh cc gi nh m phn u trong mi gi mang thng tinv knh logic v s lng gi. Cc gi tin ny li c chia thnh cc khungvic phn chia nh vy nhm thc hin vic kim tra li c th pht sinhtrong qu trnh truyn.

7/ Yu cu xc nhnYu cu ny c pht i bi LES ngay sau khi gi tin cui cng

c pht i trn knh LES TDM. N bao gm knh logic, n nh knh bohiu cho MES v khe thi gian dnh cho vic xc nhn, MES s s dngknh bo hiu ny tr li xc nhn.

8/ Xc nhnMES s gi gi tin xc nhn ti LES vo khe thi gian n nh knh

bo hiu, n s mang theo thng tin v s lng gi tin b thu li LES

thc hin vic pht li cc gi tin .Nu kt thc vic chuyn in m LES vn cn mun chuyn in th npht gi tin n nh knh logic, cn ngc li n s pht gi tin xo knhlogic.9/ Xo knh logic


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Lnh xo knh logic thc hin khi khng cn in gi cho MES iuny c ngha l MES t ng quay v trc canh trn knh NCS TDM.

10/ Trng thi ca MESSau khi LES xo ng kt ni, n s i khong 60 giy MES

quay v knh TDM. Sau khong thi gian ny n s gi trng thi ri caMES ti NCS, nhm ch ra rng MES sn sng cho vic nhn in mi.


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Hnh 4: Th tc lin lc LES - MES trong trng hp LES c knh TDM c nh


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2.1.2. Xt trng hp LES c knh TDM n nh theo thi gian

i vi cc i hot ng ch ny khi LES mun chuyn in choMES n phi yu cu NCS cp nhm knh gm c 1 knh TDM, 1 knh bohiu v mt knh chuyn in. Th tc chuyn in c thc hin nh sau:

NCS LES MES

Check mobileStatus

Request to sent massagefrom Terrestrial Network.LES check local MES link forvalidity of request

Assumed tned toNCS commonChanel

MES Status

RequestISL

MES Status

ISL

TDM Request

ISL

TDM RequestRespont

ISL

ANNOUNCEMENTNCS common

channel


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1/ Khi mt bc in c a ti t mng mt t LES s thc hin vickim tra tnh hp l ca MES xem n c b ngng cung cp dch v haykhng, sau LES s gi gi tin yu cu v tnh trng ca MES trn knhISL n NCS.

NCS s thc hin vic kim tra tnh trng hin thi ca MES xem n angri hay bn, sau n s pht gi tin tr li tnh trng ca MES n LES.

2/ Trng thi ca MESTrong trng hp MES ri NCS s pht gi tin bo trng thi ca MES tiLES trn knh ISL, ngc lai LES s phi ch cho ti khi nhn c gi tin

bo trng thi MES ri.

3/ Yu cu knh TDMKhi nhn c trng thi MES ri LES s thc hin yu cu NSC cp knh

TDM bng cch pht i gi tin TDM Request trn knh ISL.

4/ Tr li yu cu cp knhNCS s cn c vo danh sch cc knh TDM tm ra mt knh TDM chac s dng, sau n s gi thng tin v knh TDM ny ti LES qua gitin TDM Request Respont.

5/ Loan bo cuc giSau khi thc hin cp knh TDM cho LES, NCS s pht gi tin loan bo

cuc gi ti MES trn knh bo hiu knh chung ca NCS m MES angtrc canh bo cho MES c in cn chuyn cho n. Gi tin loan bo nygm c thng tin n nh knh logicMES thc hin vic ly thng tin trong gi Bullentin board. chuyn vknh LES TDM v pht gi tin tr li loan bo ti LES trn knh bo hiunhm bo rng MES quay v knh LES TDM v sn sng cho vic nhnin.

(Cc bc tip theo tng t nh trong trng hp LES c knh TDM cnh.)

2.2. Th tc lin lc MES - LES

2.2.1. Trng hp LES c knh TDM c nh(S qu trnh lin lc MES - LES trng hp LES c knh TDM c nhc ch ra trong Hnh 5)


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1/ LES TDMSau khi nh dng bc in hon thnh MES s iu chnh ti knh

TDM ca LES thch hp, vic iu chnh ny da trn vic MES ly thngtin trong gi Bulletin board c a n trn knh TDM ca NCS. Thngtin gm c knh chuyn in kt hp vi knh TDM v khe thi gian ri.Trn knh bo hiu i km vi knh LES TDM, MES s chn ngu nhinmt khe thi gian ri v pht yu cu chuyn in.

2/ Loan boKhi sn sng cho vic chuyn in MES s pht gi tin loan bo

cuc gi gi tin ny gm c thng tin v s nhn dng ca MES, LES v di bc in cng nh ch n ca bc in thuc thu bao mt t hoctrm i di ng.

3/ Bo trng thi MES bnKhi nhn c gi tin loan bo cuc gi t MES, lc ny LES tin

hnh gi thng tin v trng thi bn ca LES n NCS trn knh ISL. Khi MES s c a vo danh sch cc i ang lm vic nhm trnh trnghp mt i khc mun gi cho n.

4/ n nh knh logicLES s thc hin vic n nh knh logic cho MES trn knh bo hiu

knh chung ca n. Gi tin n nh knh logic mng thng tin v s nhn

dng MES, LES v s knh logic cng nh chiu di khung.5/ Chuyn in

Bc in s c ti LES di dng cc gi tin, trong mi gi tin baogi cng c phn mo u mang thng tin v knh logic v s lng gi tinv cc gi tin c pht lin tc khng ngt qung. Sau khi pht ton b bcin MES s chuyn v knh LES TDM.

6/ Xc nhnSau khi thu ton b gi tin ca bc in trn knh chuyn in. LES

s pht gi tin xc nhn trn knh LES TDM gm c s nhn dng ca LES,s knh logic, chiu di khung, knh chuyn in ca MES v cc gi tinLES thu li. Nu c gi tin li MES s thc hin vic pht li trn knhchuyn in.

7/ Xo knh logic


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Sau khi LES nhn tt c cc gi tin ca bc in m khng c li LESs thc hin xo knh logic v MES s quay v trc canh trn knh NCSTDM.

8/ Bo trng thi MES riKhi xo knh logic LES s ch khong 60 giy MES quay v knh

TDM ca NCS , tip sau LES s gi thng tin bo trng thi ri ca MESn NCS cp nhn v danh sch cc i ri.

9/ Xc nhn vic chuyn inTrong mt s trng hp MES yu cu vic xc nhn rng bc in

c chuyn ng n thu bao. Ngay khi bc in c nhn bi thubao LES s thc hin vic xc nhn n MES thng qua NSC chuyn dnMES trn knh TDM ca NCS.


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Hnh 5: Th tc lin lc MES-LES trong trng hp LES c knh TDM c nh


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2.2.2. Trng hp LES c knh TDM n nh theo thi gian.Trong trng hp LES hot ng ch n nh knh theo thi

gian, khi MES c in cn chuyn ti thu bao trong mng mt t hay trmi di ng khc cc bc tin hnh nh sau:

1/ Gi yu cu n nh knhKhi MES nh dng xong bc in v mun truyn i n s c

thng tin trong gi tin Bulletin board c a n trn knh TDM ca NCS bit c tn s ca knh bo hiu i km vi knh TDM. Sau n sgi yu cu n nh knh trn knh bo hiu ti NCS. Khi NCS nhn cyu cu n nh knh ny n s chuyn tip ti LES da vo s nhn dngca LES cha trong gi tin.

2/ Thng bo cho MES ch

Sau khi chuyn tip yu cu n nh knh ti LES, NCS s thc hinpht gi tin pending ti MES trn knh NCS TDM nhm mc ch cho bocho MES ch trong khong thi gian thit lp knh TDM cho LES.

3/ Yu cu n nh knh TDMKhi LES nhn c thng tin yu cu n nh knh v bit rng c

in cn chuyn qua n v tin hnh kim tra tnh trng ca MES trong danhsch LES DataBasse. Sau LES s gi gi tin yu cu n nh knh TDMti NCS trn knh bo hiu lin i.

4/ n nh knh TDM: NCS thc hin vic n nh knh TDM cn ri choLES

5/ Loan bo cuc gi ti MESSau khi nhn c knh TDM, LES s pht gi tin loan bo cuc gi

ti MES thng qua knh TDM ca NCS nhm mc ch thng bo cho MESquay v trc trn knh TDM ca LES.

6/ Yu cu chuyn in

Khi MES quay v knh LES TDM, n s gi gi tin yu cu chuynin ti LES trn knh bo hiu i km vi knh TDM. Cc bc tip sauc thc hin tng t nh trong trng hp LES c knh TDM c nh.


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2.3.Th tc thc hin mt cuc gi cu cu

Trong trng hp MES thc hin pht mt bc in cp cu, n spht bc in ny ngay ti NCS m n ang thc hin trc canh trn knhbo hiu (Signalling NCS). Sau bc in s c NCS chuyn tip tiLES trn knh bo hiu lin i ISL, LES s thc hin vic pht bc inny n trung tm phi hp cu nn RCC qua mng thng tin mt t, vch xc nhn vic nhn in ca RCC.Th tc ny c p dng trong c trng hp LES hot ng ch cpknh TDM c nh hay n nh knh TDM theo yu cu.

Chng 3. CU TRUC H THNG ACSE-C

S tng quan h thng ACSE-C (Hnh v)Nhn t bn v, h thng ACSE-C c chia thnh 3 phn chnh nh sau:

H thng my ch (HOST)

NCS LES MES

NCS TDMListening to

NCSCommonChannel

NCSSignallin

g

ISLChannel

Call toRCC


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Thit b u cui v tinh Thit b u cui mt t

Tt c cc thnh phn c lin lc qua mng cc b (Mi thnh phn

thc hin cc nhim v chuyn bit)Trong phm vi bi vit ny ch yu trnh by v thnh phn: Thit b ucui v tinh.

Thit b u cui v tinh (Satellite Front-end)Phn u cui v tinh bao gm cc khi knh s dng cho thng tin lin lcvi pha v tinh nh: knh TDM, knh bo hiu (Signalling), knh chuynin (Message), knh bo hiu lin i (ISL).Chc nng chnh ca phn ny l thc hin kt ni h thng C-ACSE vi

pha v tinh, t tin hnh lin lc vi cc trm i di ng MES.

Cc thit b x l u cui (FEP - Front End Prosecer) v tinh gm c Message FEP (5 FEP) Signalling FEP (3 FEP) TDM FEP (2 FEP) TDM Monitor FEP (2 FEP) ISL FEP (2 FEP)

Trong trn bng C cc FEP Signalling v Message thc hin thu v x ltn hiu t v tinh (tn hiu ny do MES pht ln v tinh), FEP TDM thchin pht tn hiu ln v tinh. TDM Moniter FEP thc hin thu v x l tnhiu trn bng L, cn ISL FEP th thc hin x l tn hiu thu (trn bng L)v pht (trn bng C).Tt c cc thit b u cui v tinh u c cu to phn cng c bn nhnhau v s khc bit ch phn mm iu khin.Cc FEP c t trong cc gi gi l Channel Unit. Mi Channel Unit chati a t 2 n 5 FEP, v ti mi thi im trn mi Channel Unit ch c 1

FEP hot ng (Online) cn cc FEP cn li u trng thi ch (StandBy).Trc y i LES hot ng ch n nh knh theo yu cu do tithi im thc hin lin lc n c cp 1 knh TDM kt hp vi mt knhSignalling v mt knh Message tng ng vi vic x l tn hiu ti 1 FEPTDM, 1 FEP Singalling v 1 FEP Message. Tuy nhin m bo h thnglun hot ng n nh v c tnh m th s lng cc FEP c trang bcho vic x l tn hiu trn mi knh l nhiu hn 1 FEP.


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3.1/ ISL FEPISL FEP thc hin x l knh bo hiu lin i (ISL) cung cp ng

lin lc theo c hai chiu t LES n NCS v ngc li. ng ny dngcho vic trao i thng tin c lin quan n cp nht c s d liu nh cpnht tnh trng hin thi ca MES, loan bo mt cuc gi hay vic xc nhnin.Interstation Signalling Link FEP c thit k gm 2 FEP (ISL FEP 1,2) vmt FEP lun trng thi hot ng, mt trng thi ch. Vic thay i cuhnh hot ng ca khi knh ny trong trng hp FEP th nht c s cth h thng chuyn sang hot ng FEP th hai cng c th thc hinc thng qua h thng my ch (HOST).

3.2/ TDM FEP

TDM FEP c nhim v pht TDM cho MES loan bo cuc gi haythc hin chuyn cc bc in.TDM FEP c thit k cng gm c 2 FEP (TDM FEP 1,2) mt Online vmt trng thi StandBy, vic thay i cu hnh hot ng ca khi knhny cng c th thc hin c thng qua HOST.

3.3/ TDM Monitor FEPTDM Monitor FEP c chc nng gim st khung thi gian knh TDM

c pht i bi chnh i LES hoc mt i NCS, qu trnh gim st nhm

mc ch thu tn hiu nh thi khung a n FEP Message vSignalling nhm ng b qu trnh thu.TDM Moniter FEP c thit k gm c 2 FEP (FEP 1 v FEP 2) trong ch c mt FEP hot ng (Online) v FEP cn li trng thi StandBy.Vic quy nh FEP no Online v FEP no StandBy c th c thc hin

bng cch thay i cu hnh h thng do HOST qun l.

3.4/ Signalling FEPSignalling FEP c s dng thu v gii m cc tn hiu chuyn v

t v tinh (bng C) trn knh bo hiu. N cng thu tn hiu nh thi c

a ti t FEP TDM Monitor thc hin ng b khung trong qu trnhthu.Signalling FEP c thit k gm c 3 FEP (Signalling FEP 1 to 3) mtOnline v 2 FEP cn li StandBy. S d cn ti 3 FEP trong khi knh ny ldo thit k c tnh m khi LES chuyn t ch dng knh TDMkhng lin tc sang ch hot ng lin tc. Vic thay i cu hnh hot


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ng ca khi knh ny cng c th thc hin c thng qua thay vic tli cu hnh ti HOST.

3.5/ Message FEPMessage FEP thc hin chc nng x l cc gi tin thu c trn

knh chuyn in, kim tra li v chuyn i cc gi tin thnh ni dung bcin. N cng thu tn hiu nh thi c a ti t FEP TDM Monitor thc hin ng b khung trong qu trnh thu.Message FEP c thit k gm c 5 FEP (Message FEP 1 to 5) trong ch c 1 FEP Online v 4 FEP trng thi StandBy. Vic thit k nh vycng mang tnh m cho i LES Hiphng mun nng cp ln knh TDMlin tc. Vic thay i cu hnh hot ng ca khi knh ny c thc hinthng qua HOST.

Lu : Tt c cc FEP u c cu trc phn cng ging nhau, khi chngc np phn mm khc nhau s thc hin cc chc nng khc nhau.Tt c cc FEP c HOST qun l theo a ch LAN (LAN address)

S kt ni cc FEP v tinh vi nhau c m t trong hnh v sau (Hnhv nh km)(Phn trnh by s ny s c cp khi tho lun)

Cc th tc bo dng lin quan n FEP v tinh nh o thng s cc

module, mc tn hiu v th tc thay th khi hng hc..vv, s c tho lunchung cng mi ngi trong t

a c th tc monitor cc packet bng phn mm Reflection

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