MES to LES

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BI TP LN :H THNG THNG TIN V TINH

Sinh vin : Nguyn Tin Dng Trang : 1

PHN II : PHN TCH LU THC HIN CUC GIT MES TI LES

A.CU TRC H THNG INM-C1. Khi qut chung v h thng INM-C.

H thng INM-C l h thng s hon ton, cung cp dch v telex v data giaMES v LES. u im ca h thng l gi thp. kch thcnh a s dng anten vhng. Nhc im ch yu l khng c thng tin thoi.

H thng INM-C c ua vo khai thc thng 1-1991. Thit b u cui ding INM-C c bn gm 2 phn : Mt phn thc hin chc nng giao tip ngi myl my vi tnh cn gi l DTE (data terminal equipment thit b u cui d liu),mt phn thc hin chc nng truyn d liu gia DTE v cc thit b ngoi vi, vtinh c gi l DCE (data circuit terminal equipment thit b u cui mng d

liu). Thit b u cui INM-C vi c tnh Store and forward c th giao tip vi btk mng d liu mt t no hoc vi mng di ng cng cng (PSTN), mng s dadch v ( ISDN). D liu c chuyn tip gia MES v LES vi tc 600 bit/s (vtinh th h 2) hoc 300 bit/s(v tinh th h 1).Cc thit b INM-C c th thch hpvi cc tu nh v kch thc hn chv gi thnh, chi ph thp m vn c th png hu ht cc yu cu thng tin. Cc tu c va v ln cng c th la chn INM -C t hiu qu ti u.S sau s chra cc thnh phn trong kin trc h thng INM_C gm LES, NOC,NCS v MES

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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a. Trung tm iu hnh mng NOC (Network operators center) thc hinchc nng qun l mng nh cp nhn dng cho cc i di ng ca NCS. Ngoi ran cn thc hin loan bo khi c s xut hin ca mt LES mi.lin lc gia NOCvi NCS c thc hin qua mng thng tin mt t.

b. Trm phi hp mng NCS. (Network coordination station):Mi vng i dng s c mt NCS qun l , iu khin tt c cc th ng tin lin

lc trong vng .Tri t c chia lm 4 vng do 4 NCS qun l nh sau:AORE NCS t ti Anh (Goonhilly)AORW NCS t ti Navay (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 qun l. Loan bo mt cuc gi. Xc nhn in.

Tt c cc MES hot ng trong vng bin do NCS ph trch u c yu cung nhp vo mng, mt danh sch ca tt c cc MES ng k s c NCS giti LES gip LES khi cn chuyn cuc gi ti MES t mt thu bao trong mngmt t. Trm NCS cn thc hin vic gim st cc MES m bo rng khi MESdi chuyn t vng bin ny sang vng bin khc th cuc gi ti MES s c phtli hoc hu b.

c. Trm mt t LES (Land Earth Station)Chc nng chnh ca LES l nh tuyn cc bc in gia mng v tinh v

mng mt t. Ngoi ra mi mt trm LES (nh mt Gateway) lm nhim v kt nithng tin gia v tinh v mng thng tin cng cng quc gia hoc quc t. Mi ncc th lp t mt trm LES nhm lm gim ph tn khi lin lc qua mng mt t,iu ny ngha l mi vng bin c nhiu trm LES. Trm LES c h thng Antenln c th lin lc vi v tinh tng ng trong vng ph sng, cho php kt ni ngthi vi nhiu trm di ng MES. Ch iu hnh trm LES thng l nhng cng tyvin thng ln m bo cungcp dch v trn vng rt rng cho cc trm thng tin ding MES.

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

d. Trm di ng mt t MES (Mobile Earth Station)Mi MES bao gm hai phn: mt phn thc hin chc nng giao tip ngimy l mt my vi tnh cn c gi l DTE (data terminal equipment), mt phnthc hin chc nng truyn d liu gia DTE v cc thit b ngoi vi, v tinh cgi l DCE(data circuit terminal equipment).

Trm MES l thit b c lp trn cc phng tin di ng hoc nhng nixa xi ho lnh c th thng tin lin lc vi cc thu bao b qua h thng thng tin

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INMARSAT. Cc trm MES thng c kt cu nh gn v c chc nng ph hp vitng yu cu s dng nhm m bo gi thnh thp ph hp cho mi i tng sdng.

2. Cc loi knh thng tin trong h thng INM-C:a.Knh bo hiu chung NCS:

Knh bo hiu chung NCS l mt knh TDM vi chiu di khung 8,64(s)Knh ny c pht lin tc ti tt c cc i MES trong khu vc bin ph trch caNCS. N mang theo cc thng tin v h thng, thng tin bo hiu, v cc bc inEGC t NCS ti MES , MES s t ng iu chnh ti knh bo hiu NCS thch hpkhi n tnh trng ri. Mt i NCS c th pht 1 hoc nhiu knh bo hiu chungtu thuc vo lu lng thng tin .

b. Knh TDM ca LES (LES TDM):Knh LES TDM c cng cu trc nh knh bo hiu chung ca NCS. Knh

ny pht thng tin bo hiu v chuyn tip cc bc in t LES ti MES. Vic truynhp ti knh TDM theo phng thc ti trc phc v trc tu theo mc u tinca cc gi tin.

c. Knh chuyn in:Knh ny c s dng chuyn cc bc in thng thng t MES ti

LESvic truy nhp ti knh ny da trn phng thc TDMA theo s iu khin caLES. Khi i MES nhn c n nh thi gian khi u n s pht ton b bc inca mnh khng gin on. Cc i NCS s n nh mt hoc nhiu knh chuyn incho LES tu theo lu lng thng tin.

d. Knh bo hiuMES:MES s s dng knh bo hiu c kt hp vi knh LES TDM hoc knh NCSTDM thit lp cuc gi ti LES , cc th tc ho mng (Login ) ra khi mng

(logout) ti NCS hoc chuyn cc cuc bo ng cp c ti c LES v NCS , victruy nhp ti knh bo hiu s dng phng thc truy nhp ngu nhin theo khe thigian ng k.

e. Knh bo hiu lin i (ISL) :-LES s dng 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 NCSNCS cng dng cc knh ny chuyn cc thng tin v h thng v thng tin linquan ti cuc gi ti LES. Cc i NCS thuc cc vng bin khc nhau c th dngcc knh bo hiu trong mng thng tin mt t trao i cc thng tin lin quan ticc i MES hoc kt ni cc i NCS vi trung tm khai thc mng NOC London.

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2. Cu trc knh :2.1 Cu trc knh TDM.a. Cu trc khung :

Knh LES TDM v NCS TDM c cng cu trc khung, mi khung c chiudi c nh 10368 Symbol, khong thi gian mi khung l 8,64s v c pht vi tc R=1200symbol/s . Mi khung mang theo 639byte thng tin , ban u d liu clu tr trong b nh di dng cc gi tin , gi u ca khung bao gi cng lbulletin board n mang theo cc thng tin cn thit cho vic truy cp ca i MES ,tip theo l mt hoc nhiu gi thng dng m t cc knh bo hiu c kt hpvi knh TDM hin thi . Phn cn li dnh ring cho cc gi tin bo hiu v cc bcin thngthng. B nh gm 639 byte nn nu khng cc gi tin in y

b nh th phn trng ca b nh s c in y ton b bng cc bit 0, nu migi tin c kch thc vt qu gii hn ca khung th s c ng thnh 2 gi , mtc truyn phn cui ca khung hin thi v mt truyn phn u ca khungtip theo .

Qu trnh s l i 639 byte thng tin thnh khung 10368 symbol c thchin thng qua cc bc.

_X l trn (scramber )_M ho tn hiu_X l chn

b. Cc loi gi tin knh TDM# Gi tin m t knh bo hiu (signalling channel descriptor)

Mi knh TDM c mt hoc nhiu knh bo hiu kt hp vi n, tng ng vimi knh bo hiu s c mt gi tin m t knh bo hiu pht trn knh TDM, gi tinny cho bit tn s knh bo hiu v trng thi tng khe thi gian trong cc knh bohiu pht khung thi gian trc .

# Gi tin loan bo cuc gi (announcement)Khi c yu cu thc hin vic chuyn in LES s pht gi tin ny ti i NCS

trn knh ISL, sau NCS s chuyn tip gi tin ny ti i MES xc nh thng

NCS

LES MES

ISL ISL

LES TDM

Massage Channel

Singnalling Channel

Massage Channel

Singnalling

Channel

NCSCommon

Channel

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bo LES sn sng cho vic chuyn in. Gi tin ny c s dng cho cuc giLES-to-MES v MES-to-LES.

# Gi n nh knh logic (logical channel assignment)Knh logic l cc knh TDM ca i LES hoc knh chuyn in ca i MES,

c hai knh ny u dng chuyn cc bc in thng thng hoc cp cu giaLES v MES. Gi n nh knh logic l mt trong hai cch LES bt u cuc giti MES (cch th hai l pht gi loan bo cuc gi trn knh NCS TDM). Gi tinny c s dng trong ba tnh hung : Khi MES pht tn hiu yu cu n nh knh chuyn in trc tip ti LES trnknh bo hiu, LES s tr li chp nhn yu cu bng cch pht gi tin n nh knhlogic( cuc gi mobile-to-LES ). Khi MES yu cu n nh knh chuyn in nhng LES bn nn sau n phtgi An hng dn MES tr v knh LES TDM v tip theo LES s pht gi tin nnh knh logic (cuc gi mobile-to-LES).

Trong cuc gi LES-to-mobile khi kt thc vic chuyn in nhng vn cncc bc in khc cn chuyn LES s pht gi tin n nh knh logic thay v pht tnhiu xo cuc gi.

# Gi tin Request StatusTrong cuc gi mobile- to- LES khi MES pht gi tin yu cu knh chuyn in

nhng LES khng th ngay lp tc thit lp cuc gi hoc khng chp nhn cuc gin s s dng gi tin ny thng bo vi MES, gi tin ny c th pht trc tip trnknh LES TDM hoc chuyn tip trn knh NCS TDM tu thuc MES pht gi tinbo hiu trc tip hay gin tip ti LES.

# Gi tin EGC

Mi bc in EGC c kch c t 165280 byte. Cc bc in c ln hn 256byte th c chia lm cc phn nh, mi phn gm 256 byte d liu v mi phn

tng ng vi mt gi tin EGC. Mi gi tin EGC gm phn mo u v phn thngtin, phn mo u c tn hiu kim tra tng ring v c my thu EGC s dng quyt nh c nn in cc bc in EGC b thu li hay khng. Khi tn hiu kim tratng ca c gi tin ch ra rng gi tin thu b li th my thu s kim tra phn kim tratng ca phn mo u kim tra phn mo u thu c b li hay khng, nu c thkhng in bc in c thu, nu khng th in bc in c thu .Dng n gin nht ca gi tin EGC l gi c mt phn mo u (single header), mi gi mang theo mt phn ca bc in EGC. Gi tin EGC thng c NCS pht trnknh bo hiu chung NCS TDM ti cc i MES.

2.2 Cu trc knh bo hiu

a. Cu trc khung:MES s dng cc knh bo hiu pht yu cu knh chuyn in, bo ngcp cu tiLES hoc vi mc ch login, logout ti NCS. Mi i LES/NCS c mthoc nhiu knh bo hiu tu thuc lu lng thng tin. V knh bo hiu c chias cho nhiu ngi dng do phng php truy nhp ti n l truy nhp ngu nhintheo khe thi gian. Khong thi gian mt khung ca knh bo hiu l 8.64(s) (gingvi knh TDM), mi khung chia lm 14 khe thi gian (v tinh th h 1) hoc 28 khe(v tinh th h 2).

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Mi i pht khc nhau s pht cc gi tin ca mnh theo tng burst vo cc khe thigian ngu nhin, do tnh ngu nhin nn c kh nng xy ra xung t thng tin giacc i, v MES khng c kh nng gim st qu trnh truyn tin nn NCS hoc MES

s yu cu MES pht li gi tin sau mt khong thi gian tr nht nh, nu cc i lhon c lp th kh nng xy ra xung t ln hai l rt t. Mi burst mang theo mtgi tin c di c nh 15 byte, 120 bit nu khng cc bit thng tin th cc byte

trng c in y bng cc bit 0. Cc gi tin c x l trn v m ho to ra252 symbol d liu, khi d liu cng thm mt UW (unique word -t duy nht) 64symbol to ra mt burst hon chnh pht trn ng truyn. Tc pht ca burstl 600 symbol/s - v tinh th h 1 hoc 1200 symbol/s - v tinh th h 2.

b. Cc loi gi tin knh bo hiu# Gi tin xc nhn nhn in (Acknowledgment)MES s dng gi tin ny xc nhn ti LES v nhng bc in c chuyn tiMES trong cuc gi LES-to-mobile.

# Gi tin tr li loan bo (Announcement response)Trong cuc gi mobile-to-LES i MES pht tn hiu yu cu knh chuyn in

trn knh bo hiu trc tip ti LES nhng LES bn khng th ngay lp tc p ngyu cu, nn sau mt khong thi gian khi sn sng LES s pht tn hiu loanbo cuc gi trn knh NCS TDM yu cu MES nili cuc gi, MES s s dnggi tin tr li loan bo (Announcement response) thng bo vi LES rng n angiu chnh ti knh LES TDM v sn sng cho thng tin.

# Gi tin tr li vic n nh knh logic (assigment response)

MES s dng gi tin ny tr li loan bo cuc gi ca LES trong cuc gi LES-to-mobile hoc trong trng hp LES chuyn ht mt bc in nhng vn cn nhngbc in tip theo khi n s pht gi tin n nh knh logic thay v gi tin xo cucgi v MES s s dng gi tinny tr li LES .

# Gi tin yu cu truy nhp mng (login request)Trc khi mt i MES mun s dng mt mng thng tin no chuyn

in hoc s dng dch v th n phi tin hnh truy nhp ti i NCS ca vng bin

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m MES ang hot ng bng th tc login. Th tc login s cho NCS bit MESang canh nghe trn knh NCS TDM no n pht cc tn hiu loan bo ti MES, NCS cng c th yu cu MES iu chnh ti knh TDM khc nu cn thit, tuy

nhin trong trng hp bo ng cp cu th bt k knh no cng c th c chpnhn.

# Gi bo ng cp cu (Distress alert)MES pht gi tin bo ng cp cu trong trng hp tu gp nn v yu cu s

tr gip khn cp. Gi tin ny c th c truyn ti NCS m khng cn login, NCSt ng chp nhn chpnhn cuc gi v chuyn tip tn hiu bo ng ti LES. NuLES c knh TDM c nh th tn hiu bo ng c th c chuyn trc tip ti LESv LES c trch nhim chuyn tip bo ng ngay lp tc ti RCC quc t v qucgia, trong trng hp LES khng c kh nng chuyn tip th NCS s m nhn trchnhim ny.

# Gi tin MES force clear

Trong mt s trng hp MES bt buc phi kt thc cuc gi gia chng vnhiu l do khc nhau nhng ch yu l vn li, khi MES s pht tn hiucng p xo cuc gi ti LES trn knh bo hiu, LES s xc nhn trn knh TDMkt hp.

2.3 Cu trc knh chuyn ina. Cu trc khung

Cu trc khung knh chuyn in gn ging vi cu trc khung knh TDM, tuynhin n c mt s c im ring.

- Knh chuyn in c chia s cho nhiu ngi dng, phng thc truy nhpn knh chuyn in l TDMA. V cc i pht khc nhau nn c th c s sai khcnh v tn s v ng h. Do phn mo u c thm vo cc Burst thng tin

ca tng i nhm tr gip cho vic khi phc tn s v ng h i thu.- di khung bin i ty theo kch c bc in.- Tc pht l 1200 Symbol/s hoc 600 Symbol/s ty thuc vo loi v tinh

c la chn.- Mi khung knh chuyn in mang theo (N + 1) gi tinN: l s gi tin N = 0 4

Mi gi tin gm 127 Byte c nh cng thm 1 Byte cn bng thnh 126 Byte, N + 1gi tin c sp xp thnh mt khi lu tr trong b nh trc khi chuyn thnh mtkhung cc Symbol pht trn ng truyn.

b. Gi tin trn knh chuyn inMi gi tin knh chuyn in gm 127 Byte c nh, trong Byte u tin cho bits th t bc in v 2 Byte cui cng l tn hiu kim tra tng, ngoi ra cn mt sphn nh mo u d liu. Trong bc in c th c nhiu gi tin, cc gi tin tiptheo gi thnht khng cn phn a ch.

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B. PHN TCH LU THC HIN CUC GI T MES N LES.

Da trn nhng kin thc chung v h thng INM-C bao gm cu trc h thng,

cu trc cc knh thng tin v chc nng cc gi tin cng nh chc nng ca cctrm NCS, LES v MES ta c th i su vo phn tch c th th tc cc trng hpthc hin mt cuc gi t MES n LES nh sau :

B1. Th tc thc hin mt cuc gi thng thng t MES n LES.Trng hp LES c knh TDM c nh1/ LES TDM

Sau khi nh dng bc in hon thnh MES s iu chnh ti knh TDM caLES thch hp, vic iu chnh ny da trn vic MES ly thng tin trong giBulletin board c a n trn knh TDM ca NCS. Thng tin gm c knhchuyn 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 nhin mt khe thi gian ri v pht yu cuchuyn in.2/ Loan bo :

Khi 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 incng nhch n ca bc in thuc thu bao mt t hoc trm i di ng.

3/ Bo trng thi MES bn.Khi nhn c gi tin loan bo cuc gi t MES, lc ny LES tin hnh gi

thng tin v trng thi bn ca MES n NCS trn knh ISL. Khi MES s ca vo danh sch cc i ang lm vic nhm trnh trng hp mt i khcmun gi cho n.

4/ n nh knh logic.

LES s thc hin vic n nh knh logic cho MES trn knh bo hiu knhchung ca n. Gi tin n nh knh logic mng thng tin v s nhn dng MES,LES v s knh logic cng nhchiu di khung.

5/ Chuyn in.Bc in s c ti LES di dng cc gi tin, trong mi gi tin bao gi

cng c phn mo u mang thng tin v knh logic v s lng gi tin v cc gitin c pht lin tc khng ngt qung. Sau khi pht ton b bc in MES schuyn v knh LES TDM.

6/ Xc nhn.Sau 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 knhlogic, chiu di khung, knh chuyn in ca MES v cc gi tin LES thu li. Nuc gi tin thu li MES s thc hin vic pht li trn knh chuyn in.

7/ Xo knh logic

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

8/ Bo trng thi MES ri.

Formatted: Indent: First line: 0.38"

Formatted: Indent: First line: 0.39"

Formatted: Indent: Left: 0"

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Khi xo knh logic LES s ch khong 60 giy MES quay v knh NCSTDM, tip sau LES s gi thng tin bo trng thi ri ca MES n NCS cp nht vo danh sch cc i ri.

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

c chuyn ng n thu bao. Ngay khi bc in c nhn bi thu bao LESs thc hin vic xc nhn n MES thng qua NCS chuyn n MES trnknh TDM ca NCS.

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Lu thc hin cuc gi t MES n LEStrng hp c knh LES TDM c nh

LES NCS MES

NCS TDM

Bullatin boardLES TDM

SIGNALLING CHANNEL

ISL

Logical channel

asignment

Massage

LES TDM

LES TDM

ISL

ISL

NCS TDM

Yu cu nhn tn hiu

Nu MES yu cu xcnhn in sau khichuyn in ti mngmt t.

NCS cp nht d liuch bo MES bn.

NCS cp nht d liuch bo MES ri

NCS chuyn tip xc nhnqua knh bo hiu chung

MASSAGE CHANNEL

LES TDM

Announcement

Acknowledgement

Clear

MES nh dng xong bcin cn truyn v canhnghe trn knh NCS TDM

MES chn mt knh bohiu kt hp vi LES TDMv iu chnh my pht tiknh .

MES gii m gi Bulletinboard v iu chnh tiknh LES TDM.

Quay v canh nghe trnknh NCS TDM

nnh tn s knh chuynin v iu chnh my phtn knh chuynin.

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Trng hp LES khng c knh TDM c nh.Trong trng hp LES hot ng ch n nh knh theo yu cu, khi

MES c in cn chuyn n thu bao trong mng mt t hay trm i di ngkhc cc bc tin hnh nh sau:

1/ Gi yu cu n nh knh logic.Khi MES nh dang xong bc in v mun truyn i n s c thng tin

trong gi bulletin board c a n trn knh NCS TDM bit c tn sca knh bo hiu i km vi knh TDM. Sau n s gi yu cu n nh knhtrn knh bo hiu ti NCS. Khi NCS nhn c yu cu n nh knh ny n schuyn tp ti LES da vo s nhn dng ca LES cha trong gi tin.

2/ Thng bo MES ch.Sau khi chuyn tip yu cu n nh knh ti LES, NCS s thc hin pht gi

tin pending ti MES trn knh NCS TDM bo cho MES ch trong khong thigian thit lp knh TDM cho LES.3/ Yu cu n nh knh TDM.

Khi LES nhn c thng tin yu cu n nh knh v bit rng c in cnchuyn qua n v tin hnh kim tra tnh trng ca MES trong danh sch LESData Base. Sau LES s gi gi tin yu cu n nh knh TDM ti NCS trnknh bo hiu lin i.

4/ n nh knh TDMNCS thc hin n nh knh TDM cn ri cho LES.

5/Loan bo cuc gi ti MES.Sau 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 MES quay v

trc canh trn knh TDM ca LES.6/ Yu cu chuyn in.

Khi MES quay v knh LES TDM, n s gi gi tin yu cu chuyn in tiLES trn knh bo hiu i km vi knh TDM.

Cc bc tip theo s c thc hin tng t nh trong trng hp LES cknh TDM c nh.

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Th tc thc hin mt cuc gi t MES n LEStrng hp khng c knh LES TDM c nh

B.2. Th tc thc hin mt cuc gi cp cu.Trong trng hp MES thc hin pht mt bc in cp cu, n s pht bc

in ny ngay ti NCS m n ang thc hin trc canh trn knh bo hiu (SignallingNCS). Sau bc in s c NCS chuyn tip ti LES trn knh bo hiu lin i

ISL, LES s thc hin vic pht bc in ny n trung tm phi hp cu nn RCCqua mng thng tin mt t v ch xc nhn vic nhn in ca RCC. Th tc nyc p dng trong c trng hp LES hot ng ch cp knh TDM c nhhay n nh knh TDM theo yu cu.

LES NCS MES

Canh nghe trn

knh NCS TDM

SIGNALLING CHANNEL

Assigment Request

NCS TDM

Tr v canh nghe

trn knh LES TDM

Quay vi trnknh NCS TDM

ISLAssi ment Re uest

ISL

TDM Request

ISL

TDM Assigment

ISL

MES StatustAnnouncemen

NCS TDM

Pending

NCS TDM

Announcement

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Trng hp LES khng c kh nng gi cho trung tm phi hp cu nn RCC thNCS s chuyn trc tip ti RCC.

PHN III : KT LUN

INM ng vai tr quan trng trong thng tin hin i vi cc ng dng ngycng c m rng.

Vic nghin cu, tm hiu cc yu t nh hng n suy hao ng truyn, tin cythng tin v tinh gip chng ta hiu c nguyn tc hot ng ca h thngthng tin v tinh.

Bn cnh , thc hin tnh ton suy hao ng truyn vi cc iu kin chotrc (da vo iu kin thi tit, kh hu, cc ch s tiu chun ..vv.. ca Vit Nam

lm gi thit) v phn tch lu thc hin cuc gi t MES ti LES nhm rn luynk nng tnh ton, hiu su hn v cch lin lc v qu trnh lin lc trong thng tinv tinh phc v cho mc ch thit k cc trm MES, LES v cc tuyn thng tinv tinh khc.

Vi cc ni dung trn c th thy c cc u im ca h thng thng tin vtinh nh sau :

- Cung cp dch v theo kiu im im hoc im a im v dch v nhng a hnh phc tp m thng tin mt t khng th.

- Cc thng tin khng ph thuc vo khong cch thng tin.- Dung lng knh thng tin ca cc b pht p ln.- tin cy thng tin cao.

LES NCS MES

Canh nghe trn

knh NCS TDM

Gi cho trung tmphi hp cu nnRCC

MES to LES

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