congnghe_ gprs

8/3/2019 congnghe_ GPRS

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Cng ngh GPRS

Hnh 1: Gii php GPRS ca Ericsson cho vic trin khai nhanh chng GPRS


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Dch v v tuyn gi chung GPRS (General Package Radio Service) l mt

cng ngh mi nhm cung cp nhng dch v gi IP u cui ti u cui qua

mng GSM. Vi nhng ng dng IP mi GPRS, cng ngh m trc y

khng kh thi i vi mng GSM th by gi c th trin khai v cung cp

nhng ng dng Internet v tuyn hp dn hn cho s lng ln ngi s

dng.

Dch v v tuyn gi chung GPRS (General Package Radio Service) l mt cng

ngh mi nhm cung cp nhng dch v gi IP u cui ti u cui qua mng

GSM. Vi nhng ng dng IP mi GPRS, cng ngh m trc y khng kh thi

i vi mng GSM th by gi c th trin khai v cung cp nhng ng dng

Internet v tuyn hp dn hn cho s lng ln ngi s dng.

V GPRS c thit k cho php ngi s dng lun c kt ni m khngcn s dng thm cc ngun lc ph trnn GPRS mang li nhng c hi kinh

doanh mi cho cc nh khai thc dch v di ng nhm tng doanh thu bng vic

a ra nhng dch v IP mi v thu ht thm nhng khch hng mi vi chi ph

hp l cho ngi s dng u cui. V mt u t ca nh khai thc vic nhanh

chng y mnh mc bao ph dch v l c th v GPRS tn dng c mt

cch hiu qu mng v tuyn GSM.

Gii php GPRS ca Ericsson c thit k y nhanh vic trin khai GPRS

m vn gi cho chi ph u vo thp. Cc khi chc nng ca mng GSM hin nay

ch cn nng cp phn mm, ngoi tr BSC cn nng cp c phn cng (Hnh 1).

Hai nt mng mi, nt mng h tr phc v GPRS (Serving GPRS Support Node


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SGSN) v nt mng h tr cng GPRS (Gateway GPRS Support Node GGSN)

c gii thiu. Trong gii php ca Ericsson, hai nt mng ny c th c kt

hp thnh mt nt vt l. Mt s trin khai linh hot GPRS l c th, v d: bt

u vi nt mng GPRS tp trung hp c SGSN v GGSN. bc tip theo, nodetp trung c th c tch ra thnh SGSN v GGSN chuyn dng.

Gii php GPRS ca Ericsson h tr cc giao din m ngay t u. V d giao

din gia SSGM v BSC h tr mt giao din m Gb nh c nh ngha

trong tiu chun ho ca ETSI, mang li cho nh khai thc kh nng t ti cu

hnh nhiu nh cung cp thit b.

Ericsson cng cung cp mt tp hp y thit b thit lp mt mng IP

xng sng hon chnh cng nh tt c cc loi dch v nhm gip cho cc nh

khai thc tr thnh mt nh cung cp dch v Internet ton din.

Ericsson a ra nhng gii php sng mang d liu tinh vi t cc Server truy nhp

v cc mng xng sng cho ti mt nn tng cung cp dch v hon chnh. Mt

vi v d ca gii php sang mang d liu l ATM v thit b chuyn mch khung,

b nh tuyn xng sng v tp hp, b nh tuyn truy nhp IP. Cc dch v v

IP v giI php Ericsson gm mt danh mc ln v y cc sn phm t in

thoi IP cho ti cc dch v khch hng.

Bi vit ny s a ra mt ci nhn ton din v gii php GPRS ca Ericsson.

Trong phn 2, cc node mi c thm vo mng GSM l SGSN v GGSN c

gi chung l GSN. Phn 3 m t v gii php BSS cho GPRS. Phn 4 ni v tc

ng ln b phn chuyn mch ca mng. Phn 5 cp n nh hng i vi

tnh cc, d phng v O&M. Phn cui m t mt s kha cnh v xng sng

v chuyn giao.


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2. Khi chc nng mi: Cc node GSN

2.1. Chc nng ca GSN

Hai nt mi ca h thng GSM Ericsson ph trch chuyn cc gi d liu cgi l nt h tr phc v GPRS (SGSN) v nt h tr cng GPRS (GGSN). C

SGSN v GGSN c th c biu th bi mt khi nim chung l nt h tr GPRS

(GSN).

SGSN cung cp nh tuyn gi ti v t vng SGSN a l, cn GGSN mang giao

din vi cc mng gi IP bn ngoi.

SGSN/GGSN tch bit vt l hon ton vi b phn chuyn mch ca h thng

GSM Ercisson. Khi iu khin trm gc (BSC) cn phi c mt phn cng mi

c gi l khi iu khin gi tin (PCU). Nhng thnh phn khc ca cu

trc GPRS ca Ericsson s dng cc khi chc nng ca mng GSM hin hnh

nhng yu cu phi nng cp phn mm.

Chc nng ca SGSN v GGSN c th c kt hp trong cng mt node vt l

(khi chc nng ca mng), hoc c th nm cc nt vt l khc nhau. SGSN v

GGSN mang chc nng GPRS ca mng IP xung sng v c lin kt vi b

nh tuyn IP.

Nhim v chnh ca SGSN:

- nh tuyn v truyn gi tin ti v t vng SGSN. Lu lng c nh tuyn t

SGSN ti BSC, qua BTS v ti trm di ng.

- Bo mt trn truy nhp v tuyn: mt m v nhn thc

- Qun l di ng


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- Qun l kt ni logic ti trm di ng

- Kt ni ti cc nt GSM: MSC, HLR, BSC, trung tm dch v tin nhn ngn,

v.v

- u ra ca d liu tnh cc (Bn ghi chi tit cuc gi, CDR)

Nhim v chnh ca GGSN:

- Giao tip vi mng IP gi ngoi

- Chc nng bo mt i vi Internet

- Qun l phin GPRS theo mc IP, ci t lin lc vi cc mng bn ngoi.

- u ra d liu tnh cc (CDR)

2.2. Kin trc GSN

GSN c xy dng trn nn tng gi v tuyn ca Ericsson, mt nn tng chuyn

mch gi mi, a nng v hiu sut cao.

Nn tng gi v tuyn ca Ericsson kt hp nhng tnh nng thng l lin quan

ti truyn thng d liu nh l tnh chc chn v thit thc vi nhng tnh nng

ca truyn thng tin in t nh mnh v n nh.

Nhng c im chnh ca nn tng mi ny l:

- Da trn nhng tiu chun ca ngnh c v phn cng v phn mm

- H thng c th h tr s tn ti ng thi ca nhiu ng dng trong c ng mt

node. iu ny c ngha l c th hot ng ng thi trn mt SGSN, mt GGSN

hay mt SGSN/GGSN kt hp trong cng mt phn cng.


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- B iu khin v phn lu lng hot ng vi cc b x l khc nhau. C 3 loi

b x l c s dng:

+ B x l ng dng trung tm (AP/C) cho nhng chng nng thuc trung

tm v c c im chung, nh O&M

+ B x l ng dng (AP) x l nhng chc nng c th v GPRS nh

qun l di ng.

+ B x l thit b c chuyn mn ha x l ti lu lng trong mt

giao din no nh IP qua giao din ATM

Hnh 2. Kin trc tch bit cho lu lng v iu khin

2.2.1. H thng ph GSN

Cu trc phn mm bo gm nhiu h thng ph c trin khai trong li

v cc tnh nng ng dng:


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- H thng ph truyn ti di ng (MTS) trin khai cc giao thc s dng trong

mt bng truyn ti bi nt GSN

- H thng ph iu khin di ng im ti im (MPS) iu khin tt c cc tnh

nng lin quan ti mt kt ni no , v d nh qun l tnh di ng.

- H thng ph ng k di ng tm tr (MVS) vi tnh nng VLR trong SGSN

tng t nh trong MSC

- H thng ph tin nhn ngn di ng (MSS) x l SMS thng qua GPRS

- H thng ph truy nhp mng di ng (MAS) cha cc server truy nhp da vo

mng gi bn ngoi.

- H thng ph phn phi v iu khin cc khi chc nng ca mng (NCS) vi

chc nng GPRS c lp, lin quan n a x l nh iu khin thit b

2.3. Phn cng GSN

Phin bn u tin ca GSN, GSN-25 c lp t trong mt t n 19. GSN

c cu thnh bi cc thnh phn sau:

- T khng c trang b: seri BYB501

- Ti liu khng c trang b: Mechanics, Backplane v hng dn PCB, v.v

- Bng ngun v Ethernet

- Bng x l

- Bng giao din. C mt s loi khc nhau:

+ Bng giao din vi cc giao din 4*E1 2 Mbps


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+ Bng giao din vi cc giao din 4*T1 1.5 Mbps

+ Bng giao din ATM a ch cp quang, mt SDH/Sonet 155 Mbps

vi ATM v AAL5

+ Bng giao din Ethernet, mt 10BaseT/100BaseTx

Hnh 4: Cu hnh ca GSN25

2.4. c im ca GSN

B nh tuyn IP

GSN ca Ericsson gm mt b nh tuyn tp trung. Tnh nng nh tuyn ny

c yu cu trong nt GSN vi 2 l do chnh:

- c dng nh l b nh tuyn s cp/th cp cho lu lng IP ti cc mng IP

- M rng giao din Gn/Gi

B nh tuyn cng c th lc cc gi IP trong tt c cc giao din IP.

Cng ng bin


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Ericsson a cng ng bin (Border Gateway BG) vo GGSN. N chia s

cc giao din vt l ca GGSN vi cc mng bn ngoi v mng xng sng. Mt

BG c th x l nhiu hn mt PLMN.

Tnh cc

C SGSN v GGSN u c kh nng tnh cc, v d to ra cc bn ghi d liu

cc (Charging Data Records (CDR)). Tnh nng tnh cc c thc hin trong

cc node GSN kt hp vi thit b trung gian nh Cng tnh cc Ericsson mang

li cho nh khai thc nhiu kh nng tnh cc khc nhau nh: khi lng d liu,

thi lng cuc gi, loi dch v, im ti, v.v

u ra t GSNs l ASN.1/BER c m ha v truyn qua FTP theo c ch y

hoc ko (push or pull).

S phn phi ng cc a ch IP

S phn phi cc a ch IP ng cho php nh khai thc (hoc mng

ISP/Corporate) s dng v ti s dng cc a ch IP t mt tp hp cc a ch IP

c cp cho PLMN/Network trnh vic cn mt a ch IP nh cho mi PDP

ng k ca mt thu bao. iu ny lm gim ng k s lng a ch IP c

yu cu mi mng PLMN. y l cch thc c xut phn chia cc a

ch IP.

a ch IP ng c th c phn phi bng (hoc qua) mng khch GGSN hay

mng ch GGSN khi chuyn vng (roaming). Trong trng hp phn phi a ch

IP ng mng IP khch, t GGSN khch hay my ch RADIUS c la chn bi

GGSN khch c th c s dng cung cp a ch IP ng. Trong trng hp

phn phi a ch IP ng mng ch, GGSN ch hay my ch RADIUS c la

chn bi GGSN ch c th c s dng cung cp a ch IP ng.


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GGSN cha RADIUS khch c th b sung mt my ch RADIUS bn ngoi vi

cc thng tin xc nhn t MS, v my ch RADIUS c th tr li mt a ch IP

nu nhn thc l chnh xc. i vi mi MS ring bit c th c nh dng my

ch RADIUS no kt ni. My ch RADIUS c th c nh v ti ISP hay tisite chung.

Mt DHCP khch s c a vo trong phin bn sau ca GGSN.

Chc nng bo mt ca GSN

Mt b nhn thc chn lc ci t c th ng dng cho tt c cc thu bao ca

mng ch trong node c h tr. Tr s ci t l s qui trnh nh km v quitrnh nng cp vng nh tuyn inter/intra-SGSN, n c php xy ra gia mi

qui trnh nhn thc. Tuy nhin, nhng nhn thc ny lun gn vi cc thu bao

khch. Nhn thc lun c thc hin gn v nng cp inter-SGSN RA cho c

thu bao ch v thu bao khch.

Mt tp kha c dng cho cc n lc nhn thc khng thnh cng. Kho gm

c IMSI, IMEI, nu c hiu lc, SGSN-ID, nhn dng , thi gian v ngy ca

MS/my cm tay nhn thc khng thnh cng.

GGSN m bo lu lng cho mt MS c th n t ng ISP, v d ISP m MS

c kt ni ti trong sut qu trnh kch hot PDP

Nhng kt ni an ton c th c cung cp lp 1, s dng ng dy chuyn

dng, lp 2 s dng ATM PVC, chuyn tip khung PVC, hoc PPP, hoc lp

3 s dng IPSec. Cng c th kt hp tt c yu t nu trn.

GGSN c th truy nhp vo my ch RADIUS, n c th c nh v mng s

liu bn ngoi/ISP. N cung cp nhn thc cho mc IP truy nhp vo ISP.


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GSN h tr tnh nng IPsec. Tnh nng ny c th c s dng cung cp mt

mng xong sng intra-PLMN an ton v kt ni ti cc mng bn ngoi nh

mng ISP, cc mng kt hp v cc mng PLMN khc.

Cc la chn gi lc khc nhau c hiu lc bo v GGSN khi s xm n hp

hay t chi ca cc tc ng bao gm ngun, im ti, giao thc, s cng v.v

Xem phn b nh tuyn.

X l ti trong SGSN

Trong mt khong thi gian, tt c gi tin t QoS Delay Class 1 c pht i

trc cc gi tin t QoS class 2, v cc gi t QoS Class 2 c pht i trc ccgi t QoS class 3. v.v

Lu lng ti/t cc MS c cng loi Qos Delay c th phi xp th t, v d vo

trc-ra trc, trong mi loi QoS.

Trong cc tnh hung qu ti bo ng s tng, v SGSN s loi b PDU theo h

thng duy tr cc mc QoS xc nh cng lu cng tt, chng hn u tin cho

QoS Class 1 trc QoS Class 2, v.v

Cht lng dch v (QoS)

Ti liu GPRS QoS c b sung theo GSM 03.60, ngoi tr loi tin cy. Ch

c tin cy loi 2 v 3 c b sung v chng thch hp nht cho s liu IP.

SGSN ng dng chc nng Admission Control trong mi yu cu kch hot PDP.

Chc nng ny hoc l a n qu trnh x l tip yu cu, tha thun ca QoS

vi MS hay t chi yu cu kch hot PDP.

SGSN tha thun QoS vi MS khi mc QoS c yu cu bi MS khng c

h tr bi vic kch hot PDP hay khi mc QoS c tha thun t SGSN trc


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c th c h tr bi vic nng cp vng nh tuyn inter-SGSN. Tha thun

QoS theo MS ph thuc vo d liu thu bao c lu, QoS c yu cu v

rng di thng k trung bnh, c bo co t BSC trn mi t bo (cell).

T chi yu cu c th xy ra khi s lng cc thu bao c gn ng thi trn

mi SGSN vt qu mc ti a quy nh trc.

Ngn xen theo lut

Ngn xen theo lut (LI) s c b sung. Vic b sung cho LI gm c:

- D liu ti IP

- Tnh lu ng v cc s kin

- SMS

2.5. Giao din v giao thc

Cc loi giao din trong GSN c th c chia thnh 3 nhm chnh sau:

- Giao din da trn chuyn tip khung: Gb (SGSN)

- Giao din da trn SS7: Gs, Gr v Gd (SGSN)

- Giao din da trn IP qua bt k: Gn (SGSN v GGSN) Gi, Gp

(GGSN)

Da trn chuyn tip khung: Giao din Gb (SGSN-BSS)

Tiu chun ETSI qui nh chuyn tip khung phI c dng trn giao din Gb

gia BSC v SGSN. Chuyn tip khung s chuyn giao trong sut PDU dch v

mng gia SGSN v mt BSC. Mt SGSN c th c kt ni ti mt vi BSC.


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Ngc li mt BSC ch c th c ni ti mt SGSN. Mt BSC c th s dng

mt hay nhiu kt ni vt l ni ti mt SGSN. Gb h tr FR thng qua cc kt

ni vt l nh E1 hay T1. Cc giao din c th c s dng trong cc cu hnh

di y:

- Khng to knh (non- channelised)

- To knh (channelised)

- Phn on

Vic thc hin giao din Gb trong GSN ca Ericsson l hon thon m theo nh

tiu chun ETSI.

Cc giao din da trn SS7: Gs, Gr v Gd (SGSN ti MSC, HLR v SMS-SC)

Giao thc SS7 c s dng trn giao din Gd (SMS-SC0, Gs (MSC) v Gr

(HLR). Cc giao din ny l hon ton m, v vic trin khai ca Ericsson c

phi hp vi cc tiu chun GPRS lin quan.

SGSN s phi lin lc vi mt s lng ln HLR, MSC/VLR v SMS-GMSC v

SMS-IWMSC trong mng PLMN ni b cng nh trong cc mng PLMN ca cc

MS khch. SGSN v vy s c kt ni ti mt s im chuyn giao bo hiu

(STP, c bit l mt hoc hai), nhng im c kt ni ti mng SS7 ton cu.

Cc giao din IP qua bt c giao din no: Gn, Gi v Gp

Tn gi chung chung IP qua giao din no bao gm cc loi giao din sau: Gn(giao din SGSN-GGSN), Gi (GGSN mng IP) v Gp (GGSN-mng PLMN

khc). C mt s la chn trin khai cc giao din ny vi GSN ca Ericsson.


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IP qua PPP: Ip qua PPP ng b ho c h tr nh c nu trong RFC

1548. Lp vt l h tr l E1 hoc T1

IP qua ATM: IP c chuyn sang AAL5. N c chuyn sang lp vt l l SDH

STM-1 hoc SONET STS-3c (155Mbps)

IP qua Ethernet v Fast Ethernet: Giao din Ethernet 10 Base-T (10Mbps) v

100BaseTx (100Mbps) c b sung. C hai loi giao din ny c h tr trn

cng giao din vt l v c th c cu hnh chy thc,vi giao din khng hot

ng, ti 10/100 Mbps.

2.6. Kh nng thc hin v dung lng

Ericsson cung cp hai sn phm GSN c th c nh dng l mt SGSN, mt

GGSN hay mt SGSN/GGSN kt hp:

GSN-25: Vi hai nt mng nh hn. Cu hnh ny c cung cp trong phin bn

u tin v nhm mc ch nh l mt sn phm m u cho php y nhanh

vic trin khai dch v GPRS.

GSN-100: Hai nt mng ln hn. Nt mng ny c cng dung lng ging nh

GSN-25 nhng c dung lng cho php truyn qua, s lng ngi dng v s

lng phm vi PDP hot ng. N s c a ra nhng phin bn tip theo.

Bng 1 cho thy dung lng ca GSN-25 v GSN-100 v s lng ngi dng

c gn ng thi, s lng phm vi PDP v dung lng cho php truyn qua.

Hai yu t gii hn ca GSN dung lng cho php truyn qua l s lng gi tinmi giy v s lng bt mi giy. Nt c kch thc gi tin 300 byte mi gi

(bao gm tiu IP). Con s 300 bytes mi gi tin gn vi kch thc c tnh

ton trung bnh trong cc mng IP ln. Nu kch thc gi tin nh hn, s gi tin


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mi giy s b hn ch, i vi cc gi tin di hn tc bit ti a tnh theo Mbps

s l gii hn.

Bng 1.

GSN-25 S lng

ngi s dng

c gn ng

thi ti a

S lng phm

vi PDP ng

thi ti a

Thng lng

ti a (gi

trn mi

giy)

Thng

lng ti a

(Mbps)

SGSN-25 25,000 25,000 10,000 25

GGSN-25 - 35,000 15,000 35

SGSN/GGSN-

25

25,000 25,000 7,000 15

GSN-100 S lng

ngi s dng

c gn ng

thi ti a

S lng phm

vi PDP ng

thi ti a

Thng lng

ti a (gi

trn mi

giy)

Thng

lng ti a

(Mbps)

SGSN-100 100,000 100,000 40,000 100


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GGSN-100 - 150,000 60,000 150

SGSN/GGSN-

100

100,000 100,000 28,000 70

SGSN quyt nh s lng ti a ngi s dng mc nh. GGSN quyt nh s

lng ti a phm vi PDP hot ng. Mt ngi s dng c th c n nh m

khng cn phi kch hot PDP. Ngi s dng ny c th ch s dng GPRS cho

SMS. bt u s dng cc dch v khc ngi s dng cn phi kch hot

PDP.

3. BSS cho GPRS

Chi tit h thng BSS da trn gii php GPRS cho BSS R8.0 v Ericsson s trin

khai theo giai on hng ti GPRS.

GPRS s s dng mt tp hp chung cc ngun vt l qua giao din v tuyn

chung vi mng GSM hin ti. iu ny c ngh a l c th kt hp cc knh

GPRS vi cc knh chuyn mch trong cng mt t bo. Cc ngun lc GPRS

c th c nh v ng trong-gia cc khong trng trong cc phin chuyn

mch knh, v th n s dng cc ph hiu qu hn.

GPRS s dng cc knh vt l ging nhau nh GSM chuyn mch knh nhng

mang li tin ch knh nhiu hn. Vi GPRS nhiu ngi s dng c th chia s

cng knh. Hn na, cc knh GPRS ch c xc nh khi d liu c gi ihay nhn.

3.1. Cu trc BSS cho GPRS


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GPRS v GSM cng tn ti trong h tng GSM, gip cho vic trin khai nhanh

chng v vng ph sng GPRS rng.

BSS ca Ericsson yu cu phn mm mi h tr GPRS. Phn cng mi, khi

iu khin d liu gi (Packet Control Unit-PCU) cng cn phi thm vo BSC.

BSC c th l BSC/TRC kt hp (Transcoder Controller) hay l BSC n lp.

PCU ch c th phc v cho mt BSC v ch c mt PCU cho mi BSC. PCU

thch hp vi c phn cngcBYB 501 v BYB 202.

Mt giao din m mi, giao din Gb c a vo gia BSC (PCU) v SGSN.

PCU c th c kt ni vi mt nt SGSN qua giao din Gb trc tip t mt

BSC n lp hay TRC/BSC kt hp (1), hay l qua TRC t mt BSC n lp (2),

hoc qua mt MSC t mt BSC/TRC kt hp.

Giao din A-bis hin ti c ti s dng cho GPRS do s mang c chuyn

mch knh v lu lng GPRS.

Hnh 5: Giao din m Gb ni PCU vi SGSN

Khi iu khin dliu gi (PCU)


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PCU c vai tr x l d liu gi GPRS trong BSS. c bit PCU c vai tr x l

cc lp iu khin truy nhp mi trng (Medium Access Control) v cc lp ca

iu khin lin kt v tuyn RLC (Radio Link Control) ca giao din v tuyn v

BSSGP v cc lp dch v mng ca giao din Gb. Giao din Gb kt thc PCU.

PCU cha c thit b phn mm v phn cng trung tm vi phn mm b phn.

N s c mt hoc nhiu hn b x l b phn (RPPs). Mt RPP c th c nh

dng hoc l tng thch vi c giao din Gb v A-bis hay ch vi giao din A-

bis. Chc nng ca RPP l phn phi cc khung PCU gia giao din Gb v A-bis.

u ch c mt RPP hot ng trong PCU n s tng thch vi c giao din Gb

v giao din A-bis. u c nhiu hn mt RPP, mi RPP c th tng thch vi

hoc l A-bis hoc l c Gb v Abis.

Hnh 6: PCU trong BSC

u c nhiu hn mt RPP c s dng (loi tr trng hp c 2 RPP trong

cu h nh hot ng/ch), chng s lin lc vi nhau s dng Ethernet. Mt t


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bo khng th b chia tch gia hai RPP. Nu mt RPP khng khng qun l t

bo m tin nhn nh gi ti, tin nhn s c gi tip qua Ethernet ti ng RPP.

Mt kt ni i Ethernet c cung cp phin sau (backplane) ca khung PCU.

Hn na mt s bn HUB cng cn n kt ni RPP qua Ethernet. Cc bng

HUB c nhn i v cc l do d.

PCU kt ni ti cc thit b Gb (cc ETC) qua tng i nhm v ti cc thit b

Abis (cc ETC) qua tng i nhm v tng i tc cha ti chun (subrate).

Cc RPP c kt ni vi tng i qua DL2 v ti CP qua RP knh ni tip.

Lu lng GPRS c nhn ln nhiu ln vi lu lng chuyn mch knh trongtng i tc cha ti chun.

Hnh 7: S phn b ca cc thit b GPH

Cu trc PCU c th t ti chi ph hp l cho c cc PCU nh v ln.

m rng c dung lng mt s khung cha c RPP v bng HUB c th kt ni

c.


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Cc chi tit v dung lng thc t ca PCU v RPP c trnh by trong hng

dn v m t chi tit ca PCU.

Trm gc

BTS ca Ericsson cn cc phn mm mi h tr GPRS v khng cn thm

phn cng mi. Thc t l vic ch cn nng cp phn mm s cho php trin khai

dch v vi ph sng rng khp.

Cc v tr (site) hin ti c th c ti s dng cho GPRS v n c h tr trn

c RBS 2000 v RBS 200 vi SPU++ (SPU+/SPE). C b chuyn m knh CS-1

v CS-2 c b sung trn tt c cc BTS, loi tr cho RBS 2301 khng c mtnhm DSP ch h tr cho CS-1.

Truyn dn

Giao din Abis hin ti c ti s dng cho c chuyn mch knh v lu lng

GPRS trong khi giao din gia BSS v SGSN li da trn giao din m Gb mi.

Thng qua Abis cc truyn dn hin ti v cc lin kt bo hiu s c th c tis dng cho GPRS, do s mang li mt s m u c hiu qu v ti u v chi

ph. Khng c cc kt ni truyn dn b sung no cn n (tr khi s lng cc

TRX mi site cng tng ln)

Giao din Gb l mi nhng c th nh tuyn trong sut lu lng Gb qua MSC

(nu c dung lng trong MSC cho n)

3.2. X l ngun v tuyn GPRS

GPRS da trn mt knh v tuyn logic mi c ti u ha cho gi d liu, knh

d liu gi (Packet Data Channel-PDCH). Nhng PDCH ny c th c nh v

bng nhiu cch khc nhau. Chng c th c thit lp nh nhng PDCH chuyn


22/43

dng, cc ngun lc c nh chuyn dng cho GPRS, hoc cc PDCH theo nhu

cu, phc v nh nhng ngun GPRS ng tm thi. Nhng PDCH chuyn dng

khng th c s dng cho bt k lu lng chuyn mch knh no. Cn nhng

PDCH theo nhu cu li c th c nhng ngi s dng chuyn mch knh nchim trc.

Trong R8 nh khai thc c th quy nh 0-8 PDCH chuyn dng cho mi t bo.

Khng c gii hn vt l no cho bao nhiu PDCH theo nhu cu c c trong mt

t bo, nhng n ty thuc vo vic c bao nhiu lu lng chuyn mch knh.

Trong mt khng c bt k lu lng chuyn mch knh no th c th s dng

tt c cc knh cho lu lng GPRS.

Chc nng theo di ti c trin khai trong mt vi mt hay nhiu PDCH

chuyn dng, PDCH theo nhu cu c xc nh khi s lng ngi s dng

GPRS qu cao so vi s lng cc PDCH hin ti trong t bo , g i nh rng

c nhng knh nhn ri c th s dng.

PDCH chuyn dng u tin, knh ch (MPDCH) m nh khai thc xc nh trong

mt t bo s cung cp knh iu khin chung d liu gi (PCCCH) mang theott c bo hiu iu khin cn thit bt u truyn ti gi tin. N cng h tr

cc knh lu lng gi. Nhng PDCH sau, nhng PDCH ph tr c th l knh

chuyn dng hay knh theo nhu cu v ch c s dng cho lu lng gi d liu

v truyn bo hiu lin kt. (iu ny c ngh a l MPDCH mang cc knh:

PBCCH, PCCCH, PDTCH v PACCH, trong khi mi PDCH ph tr ch mang

cc knh: PDTCH v PACCH)

Trong mt t bo khng c MPDCH (khng c PDCH chuyn dng c xc

nh) cc knh iu khin c bn nh BCCH, RACH v.v s x l vic pht v

truyn gi bo hiu ti cc my di ng GPRS.


23/43

Mt PDCH theo nhu cu s c quay tr li tp hp chung cc knh vt l (tr

thnh knh nhn ri) khi khng c my di ng GPRS no s dng knh. Ngc

li mt PDCH chuyn dng s c tr li tp hp cc knh vt l c bn ch

bng mt lnh (v d ti cu hnh ca s lng cc PDCH chuyn dng trong t bo). Bt k TCH chuyn mch knh no cng c th c ti nh dng cho

mt PDCH v ngc li, th tc ny c c tnh l chim t hn 200ms.

Trong mt t bo h tr GPRS, h thng BSS duy tr hai danh sch nhn ri

(danh sch GSM v GPRS nhn ri) vi tt c cc knh lu lng c th s dng,

khng bao gm cc PDCH chuyn dng. Ban u tt c cc knh nhn ri ny u

thuc v danh sch GSM nhn ri. Khi mt knh GPRS c yu cu, h thng

trc tin s t m mt knh PDCH chuyn dng. Nu khng knh no c tm

thy, hoc l do khng c knh PDCH no c xc nh hoc l tt c PDCH u

bn, h thng s kim tra cc danh sch GSM nhn ri. i vi cc cuc gi

chuyn mch knh n, mt knh s c t m kim theo th t trong danh sch

GSM nhn ri. Nu khng c knh no s dng c danh sch GPRS nhn ri s

c kim tra. La chn cui cng l mt knh PDCH theo yu cu s c

chim trc phc v cho cuc gi chuyn mch knh n (nu khng c knhnhn ri, GSM hay GPRS l cc knh hot ng, mt yu cu knh HSCSD a

tng s nhn ch mt TCH bng cch chim truc mt knh PDCH theo yu cu

ang bn)

Nh khai thc c th nh r ni t cc knh PDCH chuyn dng. Theo quan

im v tuyn, cc knh khng nhy tn trn knh mang BCCH nhn chung l

khng tng t nh cc knh lu lng trn cc tn s khc. Cc tn s BCCH c

th c mt s tn s ring bit v cc burst trn tn s knh BCCH khng ph

thuc vo cng sut c iu tit. Nh khai thc c th quyt nh liu cc knh

PDCH c th s c nh v trn tn s knh BCCH khng nhy tn nh l la

chn thao tc u tin hay cui cng.


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Vic phn b khe thi gian hng ln ng s c s dng (c phn bit bi

vic s dng cc c trng thi hng ln, USF)

Mt c cu a khung 52 c s dng trn cc knh PDCH

3.3. Tc ng ln mng v tuyn

Trong BSS R8.0 tc ng ca vic a vo GPRS i vi mng v tuyn c

gim thiu n mc thp nht.

Cc ngun lc GPRS c th c xc nh linh hot gia cc khong trng ca

cc phin chuyn mch knh. Hn na, cc cuc gi chuyn mch knh n c th

chim trc nhng knh PDCH theo yu cu. Cc knh PDCH theo yu cu v th

c cho l nhn ri bi cc my di ng chuyn mch knh, v s khng nh

hng ti kh nng chn trong cell.

Mt ngi s dng chuyn mch knh chim mt knh trong mt cell khng c

TCH s b chn. Mt khc mt ngi s dng GPRS i ti mt cell khng c knh

nhn ri c th c hng ti mt knh PDCH ang hot ng. iu ny l do

ngi s dng khc chim mt cht lng c phn b trn knh . Ton

b di thng trn knh phi c chia s cho ton b cc my di ng GPRS s

dng knh . Mt ngoi tr l nu mt di ng GPRS yu cu mt knh trong

mt cell khng c knh GPRS no c th c xc nh, v d khi tt c cc knh

trong mt cell c s dng nh cc knh TCH. Trong trng hp ny ngi s

dng GPRS s khng nhn c bt k cng sut no v my di ng GPRS s t

b chn trong h thng cho ti khi gim tc nghn.

Giao din v tuyn hin ti c ti u ha v lu lng thoi. Khi GPRS c

a vo cung cp, cc dch v chuyn mch knh v dch v gi d liu s phi

cnh tranh vi nhau cho cng cc ngun quang ph. Tuy nhin, nhng m phng


25/43

li ch ra rng s khng c bt k mt tc ng ch yu no ln cht lng ca cc

dch v chuyn mch knh.

Ban u lu lng GPRS c th khng ng k. n gin qu trnh a vo s

dng GPRS, trong R8 vic quy hoch cell da trn chuyn mch GSM v ci t

thng s cell s c ti s dng cho GPRS. Thc t, h thng t ng thit lp

thng s cell GPRS mi v ranh gii cell c th ging nh chuyn mch knh.

Vng nh v (Location Area LA) khng c s dng cho GPRS. Mt vng mi

c thit lp cho GPRS, gi l vng nh tuyn (Routing Area - RA). Mt RA

cha mt hoc mt s cell v vy s l mt tp hp con ca mt LA. Trong BSS

R8.0 chng c thit lp ging nhau.

Tnh nng nhy tn GPRS c h tr cho phin MS n v a khe.

BSS h tr s phc v ca cc MS s dng thu nhn khng li n tc (DRX) theo

thng s c gi i bi SGSN ti BSS.

Chc nng iu khin cng sut GPRS MS c thc hin trong BSS R8.0 nh

mt cch thc vng lp m v thng s iu khin cng sut MS c thit lp

cho mi cell. Tuy nhin, b iu khin cng sut BTS li khng c h tr trong

BSS R8.0. Thay vo b cng sut u ra y c s dng cho tt c cc

knh GPRS trong BSS R8.0.

Trong BSS R8.0 c b chuyn m knh CS-1 v CS-2 u c trin khai. T l

d liu ti a (ti lp RLC) cho CS-1 l 8kbit/s v i vi CS-2 l 12kbit/s. Tt c

bo hiu ch s dng CS-1. Tuy nhin cc b chn s liu li s dng bt c m

knh no v d nh CS-2 hoc CS-1. Trong BSS R8.0 CS-2 c ci t mc nh

nhng nh khai thc c th la chn gia CS-1 v CS-2 cho mi mc BSC.

(Trong cc c h tr bi phin bn c l RBS 2301 khng c nhm DSP th

CS-1 s c s dng).


26/43

Nhng vn v quy hoch cell trong GPRS

GPRS s s dng cc knh vt l tng t nh GSM chun. V th GPRS v lu

lng chuyn mch knh c th c hi t trong cng mt bng tn s. iu ny

s dn n vic tng trung k, v GPRS c th s dng linh hot cc knh c

li sau lu lng chuyn mch knh. iu tng i quan trng l cc site

hin ti c th c s dng, v s cell khng cn iu chnh phc v

GPRS. Cch thay th ny s gim thiu chi ph cho vic kt hp v a GPRS vo

hot ng trong mng v tuyn GSM hin ti .

Theo cch khc, mt bng tn ph c th c thit lp cho lu lng GPRS.

Nhng yu cu v iu kin v tuyn cho GPRS khng c th nh yu cu cho

thoi. Linh hot hn thoi, GPRS c th iu chnh bo hiu theo t l nhiu (C/I)

xung 5dB. Ti cng mt thi im, thit k ca GPRS gip cho vic ti u ha

C/I trn 25dB c c bng thng ln hn cho mi knh vt l c bn. iu

ny gi ra mt quy hoch cell GSM hin ti c iu chnh cho thoi l khng

ti u cho GPRS. Trong h thng GSM/GPRS pht trin sau s dng tt c 4

phng php m ha c xc nh trong tiu chun v EDGE kh thi, v

nhng ni s phn chia c bn ca ton b lu lng l cho GPRS n c th c

pht trin c tn s v quy hoch cell ring r cho GPRS. Khi trin khai GPRS

ln u di tn ring cho GPRS khng c cho l cn thit bi v lu lng

GPRS thp v tng thch kt ni cho CS-1 v CS-2 khng c h tr trong BSS

R8. Vic kt hp cc yu t trn vi nhau cng kh thi. V vy mt phn ca bng

tn c th c s dng cho c ngi s dng thoi v s liu, trong khi cc tn s

khc c th s dng cho cc ng dng yu cu tc truyn ti cao v cht lng

kt ni v tuyn c bit tt.

Nhng kt qu ca vic s dng cng quy hoch cell cho lu lng chuyn

mch v lu lng GPRS


27/43

Vic p dng chung quy hoch tn s cho cc dch v GPRS v dch v thoi cn

phi ch ti vic bo m cht lng thoi. Trong mt h thng c nhy tn m

khi lng lu lng GPRS l gii hn th iu ny khng gy ra vn g ng

k.

Nu khi lng lu lng GPRS l ng k v nu thoi trong mng v tuyn ph

thuc vo cc tnh nng gim can nhiu nh DTX v iu khin cng sut, cc yu

t tng t c th c trin khai trn cc knh GPRS. Trong GPRS, ging nh

bt k mt h thng s liu gi no, vic ti u ha mt kt ni ti 100% l khng

th thc hin. l do trng thi bng n lu lng gi d liu v nhng yu cu

tr ti a. V vy mt knh GPRS s hin th mt lot DTX t ng. Tuy nhin,

gim can nhiu nh cc khe thi gian khng c s dng c th khng

m bo cho cht lng thoi. V vy, trong nhng h thng m mt phn ln ca

ton b lu lng l cho GPRS c th cn thit phi s dng kt hp iu khin

chp nhn, iu khin cng sut GPRS v cc tnh nng khc nhm gim can

nhiu. S kt hp ny khng c h tr trong BSS R8.

Khi lin kt trong GPRS

GPRS c th iu chnh thch hp hn vi cht lng lin kt v tuyn so vi

thoi (GSM). Trong GPRS, cc phng php m ha khc nhau vi cc mc

bo v m ha khc nhau i vi cc li bit c thc hin i vi ngi s dng.

S m phng mc lin kt ch ra rng bng cch s dng m ha mnh nht

(CS-1), mt lin kt GPRS c th c duy tr mt bo hiu ti t l can nhiu

(C/I) di 6dB. y l c ch tng t nh bo hiu knh SDCCH trong GSM

chuyn mch b rt. iu ny khng ngc nhin v CS-1 trong GPRS c c th

cho vic m ha s dng trong bo hiu knh SDCCH. Ngc li, cht lng

thoi trong lin kt chuyn mch bt u duy tr C/I cao hn, v c bit l

khng th duy tr mt cht lng thoi tng i vi C/I di 9dB (h thng nhy

tn).


28/43

Cht lng kt ni v tuyn tt hn cho GPRS gip gim bt s truyn pht li

cc khi v tuyn sai lch v em li kh nng s dng nhiu phng php m

ha khi thng tin hn (CS-2, CS-3 v CS-4). Bng cch iu chnh m ha theo

iu kin v tuyn, bng thng cho ngi s dng GPRS trn mi knh vt l cbn tng khi cht lng lin kt v tuyn tng.

Tc ng ca GPRS ln cht lng thoi trong mng v tuyn

GPRS (khng bao gm EDGE) s dng iu ch chung, cu trc nhm v cc

knh v tuyn nh ca GSM chuyn mch; Nhm ny ti nhm khc, GPRS c

cng cc yu t can nhiu nh thoi. Tuy nhin, can nhiu t mt knh GPRS c

th cho l khc vi can nhiu t mt knh thoi. iu ny l do trnh t bt-tt trn

knh s liu gi khc vi trn knh thoi. Hn na, GPRS v thoi c th s dng

cc c ch iu khin cng sut khc nhau.

Trong h thng nhy tn vi s phn b ng ca lu lng chuyn mch v lu

lng GPRS trn cc knh khc nhau, can nhiu xy ra bi cc my di ng dng

thoi l mt tp hp ca lu lng GSM v GPRS. Trong mng v tuyn s dng

nhy tn v vi lu lng chuyn mch knh tri trc (pre-dominantly), mt tphp nh ca cc my di ng GPRS khng cho l s thay i tng can nhiu trong

mng v tuyn theo bt c cch thc no.

Gii php ca Ericsson trong GSM R8

Phin bn GPRS u tin ca h thng GSM ca Ericsson R8 c thit k

gim thiu nh hng ln mng v tuyn hin ti. Hai h thng m ha c hiu

lc: CS-1, h thng m ha mnh nht, v CS-2 nng t l d liu ln 48 Kbps

(4 kt ni khe thi gian). S dng ch bo v li ca CS-1, GRPS c th duy tr

kt ni s liu gia my di ng v mng ngay c trong cc iu kin lin kt v

tuyn c th dn n cht lng thoi trong GSM khng tt. Do vy, trong trin


29/43

khai ln u ca GPRS, s t bo mng GSM hin ti c th c s dng t

nht c ph sng GPRS nh ca GSM.

Vic GPRS s dng cc quy hoch cell hin ti cng gip cho ngi s dng

GPRS kt ni n cng cc BTS nh cc my di ng chuyn mch knh. V th

can nhiu cng knh v can nhiu knh ln cn c to ra bi cc my di ng

GPRS bt ngun t cng cc vng a l nh l can nhiu t nhng ngi s dng

thoi. gim thiu tc ng can nhiu t cc knh GPRS ln cc my di ng s

dng thoi, cc knh trn knh mang BCCH c th c thit lp nh l s la

chn u tin cho s phn b cc knh s liu gi.

4. CSS cho GPRS

4.1. HLR

HLR hin ti s c ti s dng cho GPRS. N cha d liu ng k GPRS v

cc thng tin nh tuyn. D liu ng k GPRS lu trong HLR l loi DPD,

APN, a ch IP, QoS v.v Thng tin HLR c th truy nhp c t SGSN qua

giao din Gr mi. i vi cc my di ng chuyn vng, HLR c th trong mt

mng PLMN khc ch khng phi SGSN hin ang phc v trm di ng .

Ch truy nhp mng ca thu bao (Network Access Mode) c b sung vo

trong b ghi ang k thu bao ca HLR. N quyt nh kiu truyn dn m thu

bao c php s dng. i vi ch truyn dn s liu gi thu bao cn truy

nhp ti mng GPRS, chng hn nh ngi s dng phi c php ng k tm

thi trong mt SGSN. Trong trng hp , HLR cha d liu ng k GPRS v

thng tin nh tuyn GPRS cho thu bao . Nu thu bao ch truy nhp n

truyn dn s liu th thu bao khng th ng k tm thi trn mt MSC/VLR.

IMSI ca mt thu bao truy nhp vo mng GPRS c th c kt hp vi a

ch (cc a ch) IP ca thu bao v cc thng tin ng k thu bao cn thit cho


30/43

truyn dn s liu phng thc gi. HLR nng cp SGSN vi cc thng tin da

trn thng tin da trn thng tin cp nht v tr t SGSN hay khi n c thay i

bi cc phng tin qun l.

HLR qun l di ng cho cc thu bao GPRS bng cch lu tr cc thng tin nh

tuyn cho cc thu bao GPRS cho cp nht v tr t SGSN, v thng bo cho

SGSN c v s thay i v tr ca thu bao.

HLR cng lu tr thng tin cho nhn thc v gii m t AUC v cung cp n cho

SGSN da trn yu cu.

Qun l cu hnh ca HLR c thc hin ging nh trong h thng GSM truynthng, chng hn nh bng cc lnh MML hay qua giao din Cng yu cu dch

v (Service Order Gateway). S lng ng k GPRS c th lu gi trong HLR

cng tng t nh s ng k GSM thng thng.

HLR h tr Tin nhn ngn c gi pht qua SGSN.

Khi tin nhn ngn ang c gi ti mt thu bao di ng, HLR kim tra xem

dch v c c cung cp khng, c bt k chc nng chn no ang hot ng v

xem thu bao c mt trong phm vi bao ph ca VLR hay khng.

Trong trng hp tin nhn ngn gi i khng thnh cng, dch v ch tin nhn s

cung cp cho HLR thng tin l c mt tin nhn trong SMS-C ang ch c

gi i ti trm di ng. Thng tin lu tr trong HLR d liu tin nhn ch

(Message-Waiting-Data MWD) cha mt lot cc a ch tin nhn gi gi i

khng thnh cng. HLR thng bo cho SMS-C khi my di ng c th li nhn

c tin nhn.

S phn b ca cc a ch IP tnh


31/43

Cch n nh a ch IP ny khng c gii thiu v n khng kh nng x l

mt ngun khan him nh cc a ch IP.

a ch IP tnh c th hoc c xc nh cho cc ng k thu bao trong HLR

hay my ch RADIUS c th c nh dng lun phn b cng mt a ch IP

cho mt thu bao xc nh. a ch tnh khng ly t HLR, n thc s l im

cui cung cp a ch IP ny theo yu cu kch hot PDP. Sau n s c kim

tra ngc li HLR. Nu a ch tnh c phn b t my ch RADIUS th s c

mt dng yu cu mt a ch ng.

S phn b a ch IP tnh cho php nh khai thc cung cp cho cc thu bao kh

nng s dng cc a ch IP lun c cung cp cho thu bao m c th gip cho

cc thu bao v nhng vn bo mt. S phn b a ch IP tnh c th c s

dng khi truy nhp cc mng bo mt s dng a ch IP kt ni cuc gi nh l

mt s kim tra bo mt.

4.2. MSC/VLR

MSC/VLR c kt ni ti SGSN s dng giao din Gs. h tr cho giao din

VMS/VLR cn nng cp phn mm.

Giao din Gs c s dng x l mt cch c hiu qu vi cc my u cui

gn vi c lu lng GPRS (chuyn gi) v GSM (chuyn mch). C hai hot

ng chnh thc hin qua giao din GS:

- Nng cp vng nh v/vng nh tuyn kt hp

Khi MS ci t c IMSI v GPRS, nng cp LA v RA c thc hin theo

cch phi hp tit kim cc ngun lc v tuyn nu c h tr bi ch vn

hnh mng. Khi MS i vo mt vng nh tuyn RA mi trong ch vn hnh

mng I, MS s gi i mt tin nhn yu cu nng cp vng nh tuyn. Nng cp


32/43

LA cng bao gm trong nng cp RA. SGSN sau s gi tip phn nng cp LA

ti MSC/VLR bng cch chuyn i RAI thnh mt s VLR. MSC/VLR ty tr

v mt VLR TMSI mi c gi ti MS qua SGSN. SGSN v MSC/VLR

thng bo mt cch ring r v tr mi ca MS ti HLR.

- Truyn ti chuyn mch knh qua GPRS

Khi MS ci t c IMSI v GPRS trong mt mng vn hnh trong ch vn

hnh mng I (l 1 trong 3 cch x l CS paging), MSC/VLR s thc hin truyn

ti cho cc dch v chuyn mch knh qua SGSN.

Trong ch I, khng ging ch II v III, GRPS v truyn ti CS c kt hpvi nhau. S kt hp truyn ti c ngha l mng gi i cc thng bo truyn ti

cho cc dch v chuyn mch knh trn cng mt knh nh vi cc dch v

chuyn gi, v d nh trn knh paging GPRS hay trn knh lu lng GPRS, MS

ch cn kim sot ng knh .

MSC/VLR cng h tr gi SMS qua GPRS. MSC/VLR c th yu cu SGSN ly

thng tin v lin lc v tuyn k tip vi my di ng GPRS. N c th c s

dng y nhanh qu trnh gi tin nhn SMS. Nu gi tin nhn SMS qua mng

chuyn mch knh GSM khng thnh cng, MSC/VLR c th gi li SMS khi

SGSN thng bo cho MSC/VLR v lin lc v tuyn vi thu bao di ng.

4.3. SMS-GMSC v SMS-IWMSC

SMS-GMSC v SMS-IWMSC khng b nh hng bi vic thc hin SMS qua

GPRS. SGSN s c th kt ni ti SMS-SC qua giao din mi Gd l giao din da

trn MAP. Phin bn MAP. N s cho php MS c gn vo cc dch v GPRS

gi hoc nhn SMS qua cc knh GPRS.

4.4. AUC


33/43

Trung tm nhn thc (AUC) l mt b phn ca GSM cung cp cho HLR 3 kh

nng cn cho qu trnh nhn thc v gii m c s dng trong mng.

Nhng tnh nng chnh ca AUC Ericsson:

- C th phc v c ti 4 triu thu bao trong mt node

- c thit lp nh mt modun ng dng c lp

- c thit k cho cc cu hnh linh hot

- Dung lng c th cn i

- D liu nhn thc v gii m c cung cp thi gian thc

AUC to ra cc d liu nhn thc v gii m da theo nhng quy nh GSM c th

ca Vin tiu chun Vin thng chu u (ETSI). Mc ch ca tnh nng bo mt

nhn thc l bo v mng li khi nhng s dng tri php. N cng cho php

bo v thu bao PLMN bng cch t chi kh nng nhng k xm nhp gi mo

ngi c php.

S liu nhn thc c s dng m bo rng cc thu bao ang truy nhp vo

h thng l nhng thu bao c khai bo v khng phi l nhng ngi khc

ang s dng cng nhn dng thu bao di ng quc t (International Mobile

Subscriber Identity-IMSI).

D liu gii m c s dng m bo tnh bo mt trn cc knh v tuyn vt

l.

Vic gii m ngn cho thng tin ca ngi s dng v bo hiu c hiu lc hay b

l cho cc c nhn khng c php s dng.


34/43

AuC cha cc thut ton A3/A8 c s dng to ra cc kho nhn thc v gii

m. AuC c cu to gn khch hng thut ton A3/A8 c th.

Th tc nhn thc cho cc thu bao GPRS v GSM l nh nhau. Thay i trong

bo mt cho GPRS ch lin quan n gii m. S thay i ny khng yu cu bt

k mt s nng cp AuC no nn chc nng nhn thc ca GPRS vn ging nh

ca GSM. i vi GPRS, thut ton mi A5 cho gii m c xc nh. iu ny

c ngha l SGSN cng nh nhng u cui GPRS mi phi h tr cho thut ton

mi A5.

4.5.EIR

B ghi nhn dng thit b (EIR) l mt b phn quan trng ca GSM lu gi c s

d liu (CSDL) v nhn dng phn cng duy nht ca cc trm di ng.

CSDL EIR gm cc danh sch ba mu: Trng, Ghi v en. Danh sch Trng cha

cc nhn dng thit b ca cc my cm tay c ty s dng. Danh sch mu

Ghi cha nhn dng thit b c php s dng nhng b kim sot. Danh sch

en cha cc nhn dng thit b khng c php s dng, c th l c bo mt

hay do h hng.

EIR c kt ni ti trung tm chuyn mch nghip v di ng (MSC) qua mt

kt ni bo hiu (SS7), n cho php MSC kim tra tnh hp l ca thit b c s

dng bi mt thu bao, v d nh vic ng k.

Mt MS khng c ph chun loi no, gp s c hoc b nh cp c th c

chn theo cch ny. EIR kt ni ti SGSN s dng giao din Gf. Ericsson khng

cung cp giao din Gf trong phin bn u. Chc nng EIR trong GPRS cng

ging nh trong GSM.


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Trong vic m rng EIR c iu khin bi cc nh khai thc s c mt EIR

trung tm (CEIR) c qun l bi Hip hi MoU (Memorandum of

Understanding). Hip hi MoU phi hp cc th tc m nh thit b gi v li

s c xc nh. CEIR c thit k vi vai tr nh l mt CSDL ton cu qua cc thnh vin ca MoU c yu cu trao i d liu danh sch en. CEIR

c t Dublin, Ireland.

Mt giao din qun l ni ti CEIR cho php mt nh khai thc nht nh t ng

nhn/trao i thng tin danh sch en.

5. Qun l tnh cc, tr gip v qun l mng li trong GPRS

5.1. Cng tnh cc (BGw)

Cng tnh cc (BGw) ti u ha vic a ra cc dch v GPRS trong mng di

ng bng cch a vo cc chc nng lm n gin ha qu trnh x l thanh

ton GPRS trong cc h thng tnh cc. c bit, tnh nng x l tin tin rt c

gi tr.

i vi cc nh khai thc a GPRS vo mng di ng, thi gian tip th lun

rt quan trng. iu c bit quan trng l nhng thch nghi cn n trong cc h

thng qun l v tnh cc s khng lm chm tr vic a vo khai thc GPRS.

Tiu ch tnh cc c s dng cho dch v chuyn gi nh GPRS khc v c

bn so vi nhng nguyn tc dng cho cc dch v chuyn mch knh, v d da

vo lu lng thay cho da vo thi gian. Giao thc s liu gi (PDP) c th hot

ng trong mt thi gian rt di trong khi truyn dn s liu thc ch c th din ra

tng t. Trong nhng trng hp nh vy, thi gian tr thnh tiu chun tnh

cc khng quan trng lm so vi khi lng d liu.


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Thng tin v tinh cc phi c thu thp t cc nt SGSN v GGSN mi, chng

s dng cc giao din khc ngoi AXE MSC v to ra nhng loi CDR mi.

Nhng loi CDR mi:

- S-CDR, lin quan ti s dng mng v tuyn, c gi t SGSN

- G-CDR, lin quan ti s dng mng s liu bn ngoi, c gi t

GGSN

- M-CDR, lin quan ti hot ng qun l di ng, c gi t SGSN

(khng c h tr trong phin bn GSN u tin)

- CDRs gn vi ng dng ca dch v tin nhn ngn qua GPRS.

Mt PDP c th to ra mt s S-CDR v G-CDR. Kt qu tng phn c to ra

tng qung u n (chng hn 15 pht mt ln) hoc l ngay khi mt lng d

liu nht nh c truyn pht. Cc CDR t mt PDP cng c th c gi t

mt s SGSN, nu thu bao GPRS di chuyn v thay i vng nh tuyn SGSN.

Chun GPRS xc nh chc nng cng tnh cc (Charging GatewayFunctionality - CFG) c th hoc c trin khai nh mt thnh phn mng trung

tm ring r hoc c phn b cho cc nt GSN. BGw thc hin vai tr ca cng

tnh cc nng cao, cung cp tt c nhng chc nng cao hn c xc nh trong

tiu chun. N bao gm tt c nhng g ngoi cc tp n gin da trn truyn ti

CDR m c th c x l trc tip bng cc GSN.

BGw cho php tnh cc vic s dng dch v truyn s liu vi nh hng nhnht ln h thng tnh cc hin ti l c th thc hin. BGw cng c th truyn

d liu n nhng ni m h thng tnh cc c th nhn dng, hoc n c th

c s dng xy dng nhng phn ng dng tnh cc mi, c bit l thch

hp vi tnh cc theo lu lng. iu ny gip cho c th gii thiu cc dch v


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truyn s liu nhanh chng v c th tnh cc ngay cho cc dch v. y l gii

php tm thi c s dng cho ti khi h thng tnh cc c iu chnh x

l vic tnh cc theo lu lng hoc c s dng nh l mt gii php lu di

nu thch hp.

Tnh cc cho cc dch v truyn s liu c th c n gin ha rt nhiu c

bit vi tnh nng tu chn X l tin tin c gii thiu trong BGw R7.0. X l

tin tin c 3 chc nng: giao din i chiu, phn loi v CSDL CDR.

i chiu CDR c th s dng tng hp thng tin t mt s CDR c to ra

trong sut mt phin. CDR c th c to ra t nhiu SGSN khc nhau trong

mng (khi ngi s dng di chuyn trong sut phin) hoc t cc loi nt mng

khc (SGSN, GGSN, MSC hoc my ch truy nhp), hoc t cc thnh phn bn

ngoi chng hn nh cc ISP. Tt c nhng d liu ny c th c phn tch v

tp hp vo mt CDR hon chnh c cha tt c d liu cho ton b mt phin.

Thm ch nu d liu tnh cc c gi ti t cc GSN ti nhng khong u

n, h thng tnh cc c th s ly d liu mt cch ngu nhin hn, chng hn

mt ln mi gi, mt ln mt ngy hoc khi PDP b gin on.

Phn loi loi c th c s dng t th ghi gi cc vo CDR. BGw nh

vy c th c s dng nh l mt nt phn loi hon chnh hoc lm mt s

phn loi trc, n ty thuc vo cc kh nng ca h thng tnh cc v vo s

phn phi thuc chc nng c nh khai thc quan tm hn. V d, c th chuyn

thng tin da trn khi lng c to ra t cc nt GPRS v trong my ch truy

nhp Internet (Internet Access Server- IAS) sang phng php tnh cc da trn

thi gian. BGw c th chuyn d liu da trn khi lng nh megabyte c gi

i sang d liu da trn thi gian m h thng tnh cc c th x l. Mt nh

khai thc c th quyt nh mt megabyte d liu bng 10 pht thi gian m

thoi tng ng vi mt chi ph hp l tnh theo loi tin c s dng ca nh


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khai thc. BGw c th lm tt c nhng php tnh ny, v hon ton c th nh

dng s dng theo yu cu ca nh khai thc.

Tnh nng CSDL c s dng lu tr d liu mt cch an ton trong khi n

ang i phin kt thc vic i chiu c hon thnh. iu ny l cn thit

nu i chiu c thc hin cho cc CDR c to ra trong sut mt thi gian

di, chng hn mt ngy. CSDL cng c th c s dng lu tr d liu trong

cc khong thi gian di hn c x l sau.

V tnh cc dch v truyn s liu l mt vn phc tp, mt nh khai thc c

th khng c p ng yu cu vi ch mt cng c m c th cn n mt gii

php cha kha trao tay. Cng c th yu cu nhng ng dng thch hp c thit

lp theo yu cu c th ca khch hng.

5.2. Cng yu cu dch v (SOG)

Cng yu cu dch v (SOG) hin ti cn phi nng cp phn mm h tr cho

cc dch v GPRS. N c tc dng h tr vic cung cp cc s liu GPRS trong

HLR.

5.3. OSS

H thng tr gip iu hnh (OSS) h tr qun l tt c cc thnh phn mng lin

quan n GPRS trong mng GSM.

OSS gip cho nh khai thc c th d dng qun l cc thnh phn ca mng. Cc

nt mng dch v GPRS, SGSN v GGSN trn Hnh 8 cng vi cc kt ni gnvi GPRS gia cc thnh phn mng bt k.


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Hnh 8: Cc thnh phn mng trong mng GPRS

Chc nng qun l thnh phn mng ca cc nt GSN nm trong chnh cc nt

mng v c thc hin trong mt trnh duyt Web OSS s dng giao thc

http v Java Applets.

H tr OSS ca SGSN v GGSN

Qun l li

Nhng x l cnh bo nh kha, x l sau v chuyn tip ti cc h thng NMS

nhiu nh khai thc c kt hp hon ton vi nhng chc nng qun l li khc

ca OSS. Nhng cnh bo c hin th thnh nhng danh sch v cc biu tng

ca cc thnh phn trong mng trn bn thay i mu sc, hnh dng v kch

thc tu theo nhng cnh bo c gi n.

Qun l hin th

Giao din OSS m cho vic nhp d liu hin th c tng thch nhn d liut cc nt SGSN v GGSN nh l mt dch v khch hng.

Qun l cu hnh


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Cu hnh v s vn hnh ca SGSN v GGSN c thc hin bng trnh duyt

Web OSS. Cc tp, nh phn mm c th c gi i gia OSS v cc nt dch v

GPRS vi cc chc nng x l tp chun.

H tr OSS ca cc chc nng GPRS trong MSC, HLR v AUC

MSC, HLR v AUC cn thit cho vic cung cp cc dch v GPRS trong mng.

Qun l li, hin th v cu hnh ca cc chc nng GPRS c kt hp vi cc

chc nng OSS khc cho nhng phn qun l ny v cc thnh phn mng.

H tr OSS ca cc chc nng GPRS trong BSS

Qun l li

X l bo hiu lin quan n GPRS c kt hp hon ton vi cc chc nng

qun l li ca BSC v BTS. OSS cung cp cc kh nng phn tch v x l tp

trung ch yu vo cc vn ca GPRS.

Qun l hin th

Nhng thng k hin th ca cc dch v GPRS c kt hp vi cc thng k x

l cho cc chc nng BSS khc trong cc tnh nng qun l hin th ca OSS. Tt

c cc thng k lin quan n GPRS c th c trnh by thnh nhng biu

cho cc nh khai thc.

Qun l cu hnh

Ci t thng s cho cc chc nng GPRS trong BSC v BTS c kt hpvi cc chc nng qun l cu hnh OSS khc. S kt hp ny cho php chia tch

ti u dung lng v tuyn gia ngi s dng chuyn mch knh v chuyn

mch gi trong mng.


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6. Phn li/Truyn dn trong GPRS

GPRS a ra nhng yu cu mi v phn li v truyn dn:

- Truyn dn trong mng v tuyn cn h tr GPRS, v

- Cc GSNs cn phi c kt ni s dng mt mng IP xng sng

Truyn dn hin ti gia BTS v BSC c th c s dng x l lu lng

GPRS v li ch chnh l kt ni truyn dn tng t gia BTS v BSC cng c

s dng cho GPRS, v vy khng kt ni b sung no c yu cu nu dung

lng c th p ng c trn cc kt ni hin ti.

C th s dng cc MSC ca Ericsson cho cc giao din Gb kt ni cho gia

BSC v SGSN. Theo cch cc tuyn SGSN c nh tuyn qua MSC m

chng c th c cng nhn ln nhiu ln. Cn lu gii php ny cn dung

lng tng i nhm (GS) v mch u cui tng i trong MSC.

Mt mng chuyn tip khung (chuyn mch) c th c s dng gia BSC v

SGSN t c hiu sut s dng ca dung lng truyn dn. N cng c thc s dng kt hp vi kt ni cho MSC nh trnh by trn.

Hnh 9 m t nhng thnh phn ct li ca GPRS (FR, IP, Qun l mng GPRS v

mng IP bn ngoi).


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Hnh 9: Mng GPRS vi cc mng li

Cc GSN c ni vi nhau s dng mt li IP. N c th hot ng

trn E1/T1, Ethernet v truyn dn SDH/Sonet (qua ATM, PPP hoc FR)

Ericsson h tr cc cng ngh WAN sau cho phn li IP GPRS:

- E1 hoc T1 (theo knh, khng theo knh, phn on) vi PPP hoc FR (FR

h tr c FR pure DTE cho kt ni ti mt mng FR hoc PPP nh FR vi

DTE/DCE FR)

- ATM 155, MMF, STM-1/Sonet-3c, IP c in

Trong trng hp s dng ATM, tnh nng ny c kt hp trong GSN ho nthnh cc kt ni ATM. ATM Adaption Layer AAL5 c h tr cng nh IP qua

ATM c in


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C mt s gii php trin khai nhng mng ny s dng mt tp hp rng cc

sn phm truyn s liu ca Ericsson, gm b nh tuyn IP l i, bin v tp hp,

cc tng i li v bin ATM, tng i chuyn tip khung, v.v

congnghe_ gprs

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