Thong Tin Di Dong

Hc vin CNBCVT

TS. Nguyn Phm Anh Dng

THNG TIN V TINH

LI NI U T khi ra i cho n nay thng tin di ng tr thnh mt ngnh cng

nghip vin thng pht trin nhanh nht. p ng cc nhu cu v cht lng v dch v ngy cng nng cao, thng tin di ng khng ngng c ci tin. n nay thng tin di ng tri qua nhiu th h. Th h th nht l th h thng thng tin di ng tng t s dng cng ngh a truy nhp phn chia theo tn s (FDMA). Tip theo l th h hai v hin nay th h ba ang dc chun b a vo hot ng. Th h bn ang c tch cc nghin cu. Thng tin di ng th h hai s dng k thut s vi cc cng ngh a truy nhp phn chia theo thi gian (TDMA) v m (CDMA). y l cc h thng thng tin di ng bng hp vi tc bit thng tin ca ngi s dng l 8-13kbit/s. Hai thng s quan trng c trng cho cc h thng thng tin di ng s l tc bit thng tin ca ngi s dng v tnh di ng. cc th h tip theo th h hai cc thng s ny ngy cng c ci thin. Thng tin di ng th h ba c tc bit ln ti 2Mbit/s. Th h bn c tc ln ti 50Mbit/s v cao hn na.

Cc h thng thng tin di ng th h hai c xy dng trn cc tiu chun : GSM, IS-95, PDC, IS-136 pht trin rt nhanh nhng nm 1990. Cc yu cu v ch v mi ca cc h thng thng tin di ng, nht l cc dch v truyn s liu i hi cc nh khai thc phi a ra c cc h thng thng tin di ng mi. Trong bi cnh ITU a ra n tiu chun ho h thng thng tin di ng th h ba vi tn gi IMT-2000 t c cc mc tiu chnh sau y:

Tc truy nhp cao m bo cc dch v bng rng nh truy nhp internet nhanh hoc cc ng dng a phng tin, do yu cu ngy cng tng v cc dch v ny.

Linh hot m bo cc dch v mi nh nh s c nhn ton cu v in thoi v tinh. Cc tnh nng ny s cho php m rng ng k tm ph ca cc h thng thng tin di ng.

Tng thch vi cc h thng thng tin di ng hin c m bo s pht trin lin tc ca thng tin di ng . Nhiu tiu chun cho h thng thng tin di ng th h ba IMT-2000 c

xut, trong hai h thng WCDMA UMTS v cdma-2000 c ITU chp thun v c a vo hot ng. Cc h thng ny u s dng cng ngh CDMA iu ny cho php thc hin tiu chun ton th gii cho giao din v tuyn ca h thng thng tin ng th h ba.

WCDMA UMTS s l s pht trin tip theo ca cc h thng thng di ng th h hai s dng cng ngh TDMA nh: GSM, PDC, IS-136. cdma-2000 s l s pht trin tip theo ca h thng thng tin di ng th h hai s dng cng ngh CDMA nh: IS-95.

Thng tin di ng th h bn s l s hi t ca cc h thng truy nhp v tuyn bng rng khng dy nh WLAN, WiMAX vo cc h thng thng di ng. Cc mng

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thng tin di ng th h bn s l cc mng ton IP. Mng truy nhp v tuyn cho th h bn cng s hon ton mi p ng c nhu cu truy nhp bng rng. OFDMA l cng ngh a truy nhp v tuyn y trin vng cho th h bn.

Mn hc "Thng tin di ng" l mn hc chnh c ging cho sinh vin vin thng nm cui ca i hc Cng ngh Bu chnh Vin thng. Gio trnh " Thng tin di ng" s cung cp cc kin thc ca cc h thng thng tin di ng th h hai v ba ang c s dng rng ri trn th gii nh: GSM/GPRS, W-CDMA v cdma2000. Gio trnh ny c ging sau khi sinh vin hc cc gio trnh nh: "Truyn dn v tuyn s" v "L thuyt tri ph v a truy nhp v tuyn". Gio trnh bao gm chn chng. Chng u trnh by khi qut chung v s pht trin ca cc h thng thng tin di ng, kin trc ca cc h thng thng tin di ng v ng dng IP cho cc h thng thng tin di ng.. Chng 2 nghin cu v cc cng ngh to ni dung v truyn cc ni dung ny cho cc dch v thng tin di ng nh: ting, hnh nh, truyn a phng tin. Chng 3 trnh by h thng thng tin di ng 2G GSM/GPRS. Chng 4 v 5 trnh by cc vn lin quan n h thng thng tin di ng 3G WCDMA UMTS/HSPA nh: giao din v tuyn v min chuyn mch gi ca mng li. Chng su v by c ni dung tng t nh cc chng ba v bn nhng dnh cho cdma2000 1x/1xEVDO. Chng 8 cp n cc vn quy hoch v thit k mng thng tin di ng. Chng chn bn v hng pht trin cc h thng thng tin di ng n th h bn.

Cc chng ca ti liu ny u c kt cu hp l sinh vin c th t hc. Mi chng u c phn gii thiu chung, ni dung, tng kt, cu hi vi bi tp. Cui ti liu l p n cho cc bi tp.

H Ni ngy 13 thng 7 nm 2007 Tc gi

MC LC

Chng 1. Tng quan thng tin di ng 1 1.1. Gii thiu chung 1 1.2. Qu trnh pht trin thng tin di ng 1 1.3. Kin trc GSM 3 1.4. Kin trc GPRS 5 1.5. Kin trc 3G WCDMA UMTS R3 6 1.6. Kin trc 3G WCDMA UMTS R4 13 1.7. Kin trc 3G WCDMA UMTS R5 15 1.8. Kin trc 3G cdma2000 17 1.9. nh a ch IP 27 1.10. Truyn tunnel IP trong IP 38 1.11. IP di ng (MIP) 39 1.12. Cu hnh a l ca h thng thng tin di ng 46 1.13. Tng kt 49 1.14. Cu hi 50 Chng 2. Cc s x l tn hiu a phng tin v dch v 51 trong cc h thng thng tin di ng 2.1. Gii thiu chung 51 2.2. M u 51 2.3. X l nh 52 2.4. X l ting v m thanh 58 2.5. Cc CODEC ting 65 2.6. Cc h thng x l tn hiu a phng tin 72 2.7. Cc phng php cung cp dch v a phng tin 76 2.8. Cc phng php phn b thng tin a phng tin 81 2.9. Cc giao thc ng dng v tuyn (WAP) 84 2.10. Cc phng php truyn bn tin a phng tin 85 2.11. Tng kt 88 2.12. Cu hi 89 Chng 3. H thng thng tin di ng GSM/GPRS 90 3.1. Gii thiu chung 90 3.2. M u 90 3.3. Cc knh vt l cu GSM 91 3.4. Cc knh logic ca GSM 103 3.5. Giao din v tuyn ca GPRS 110 3.6. iu khin ti nguyn v tuyn 114 3.7. Truyn dn trong GSM 118 3.8. Truy nhp mng s liu t GSM 125 3.9. Cc s truyn s liu qua GSM 128 3.10. Cc s truyn s liu qua GRRS 135 3.11. Mt s trng hp nh tuyn lu lng 137 3.12. M hnh an ninh GSM 141 3.13. Cc kin trc giao thc ca GSM v GPRS 142

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3.14. Tng kt 148 3.15. Cu hi 149 Chng 4. Giao din v tuyn ca WCDMA v HSDA 150 4.1. Gii thiu chung 150 4.2. M u 150 4.3. Kin trc giao din v tuyn WCDMA/FDD 151 4.4. Cc knh ca WCDMA 153 4.5. S knh vt l WCDMA/FDD 161 4.6. S tri ph, ngu nhin ha v iu ch 164 4.7. S x l tn hiu s 171 4.8. Cu trc khung knh DPCH 175 4.9. iu khin ti nguyn v tuyn v cc th tc lp vt l 178 4.10. Truy nhp gi tc cao (HSPA) 189 4.11. Phn tp pht 197 4.12. Tng kt 198 4.13. Cu hi 200 Chng 5. Min chuyn mch gi ca UMTS 201 5.1. Gii thiu chung 201 5.2. Cc knh mang (Bearer) 201 5.3. Kt ni bo hiu v lu lng 202 5.4. Cc bc UE truy nhp vo cc dch v chuyn mch gi UMTS 203 5.5. nh tuyn cc gi ca ngi s dng v truyn ti trong UMTS 205 5.6. Cc s nhn dng knh mang v chuyn i gia cc nhn dng ny 207 5.7. Lp cu hnh a ch trong UE 208 5.8. Th tc ng nhp GPRS (ch Iu) 209 5.9. Cc th tc tch cc PDP context 210 5.10. Cc trng thi PDP context v chuyn i trng thi 215 5.11. Cc th tc n nh knh mang truy nhp v tuyn 217 5.12. Kin trc ngn xp giao thc min chuyn mch gi 219 5.13. Truy nhp cc mng IP thng qua min PS 229 5.14. M hnh an ninh WCDMA UMTS 238 5.15. Tng kt 239 5.17. Cu hi 240 Chng 6. Giao din v tuyn cdma2000 1x v 1xEVDO 241 6.1. Gii thiu chung 241 6.2. M u 241 6.3. Kin trc giao din v tuyn cdma2000 1x 242 6.4. Cc knh ca cdma2000 1x 244 6.5. S knh vt l 256 6.6. M tri ph nh knh v m ngu nhin nhn dng ngun pht 260 6.7. M ha knh 263 6.8. iu khin ti nguyn v tuyn 264 6.9. Giao din v tuyn 1xEVDO 265 6.10. Phn tp pht 274 6.11. Tng kt 275

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6.12. Cu hi 276 Chng 7. Min chuyn mch gi ca cdma2000 1x 277 7.1. Gii thiu chung 277 7.2. M hnh chc nng 277 7.3. Th tc MS truy nhp vo cc dch v chuyn mch gi ca 278 cdma2000 1x 7.4. nh tuyn gi s liu v truyn ti 280 7.5. Kin trc giao thc cho cc dch v s liu gi 282 7.6. Kin trc giao thc gia MS v PDSN 288 7.7. M hnh an ninh cdma2000 1x 290 7.8. Tng kt 291 7.9. Cu hi 292 Chng 8. Quy hoch mng thng tin di ng 293 8.1. Gii thiu chung 293 8.2. Tng quan quy hoch v trin khai mng thng tin di ng 293 8.3. Phn tch vng ph v tuyn 298 8.4. Phn tch dung lng 307 8.5. Tng kt 311 8.6. Cu hi v bi tp 312 Chng 9. Pht trin mng thng tin di ng n 4G 315 9.1. M u 315 9.2. Hi t mng WLAN vi 3G 315 9.3. Thng tin gi IP trong cc mng thng tin di ng 318 9.4. Thng tin di ng 4G 319 Hng dn gii bi tp 321 Ph lc 330 Thut ng 334 Ti liu tham kho 345

Chng 1. Tng quan thng tin di ng

Chng 1 TNG QUAN THNG TIN DI NG

1.1. GII THIU CHUNG 1.1.1. Cc ch c trnh by trong chng

Qu trnh pht trin cc h thng thng tin di ng t 1G n 3G Cc kin trc cu cc h thng thng tin di ng 2G v 3G Cc vn ni mng thng tin di ng trn c s IP: nh a ch, truyn

tunnel v MIP Phn chia vng a l trong cc mng thng tin di ng

1.1.2. Hng dn

Hc k cc t liu c trnh by trong chng Tham kho thm [5],[6].

1.1.3. Mc ch chng

Hiu tng quan cc h thng thng tin di ng ca cc th h khc nhau t 1G n 3G

Hiu c cc kin trc mng 2G v 3G Hiu cc vn chnh trong ni mng thng tin di ng trn c s IP Hiu c cch phn chia vng a l trong cc mng thng tin di ng.

1.2. QU TRNH PHT TRIN THNG TIN DI NG Cc cng ngh TTD c chia thnh ba th h: th nht, th hai v th ba c vit tt l 1G, 2G v 3G.

Cc h thng 1G m bo truyn dn tng t da trn FDM vi kt ni mng li da trn TDM. Th d v 1G l AMPS (Advanced Mobile Phone System: h thng in thoi di ng tin tin) c s dng trn ton nc M v NMT (Nordic Mobile Telephone System: h thng in thoi di ng Bc u) hin ang cn c s dng ti nhiu nc Ty u. Thng thng cac cng ngh 1G c trin khai ti mt nc hoc nhm cc nc, khng c tiu chun ha bi cc c quan tiu chun quc t v khng c nh dnh cho s dng quc t. Khc vi 1G, cc cng ngh 2G c thit k trin khai quc t. Thit k 2G nhn mnh hn ln tnh tng thch, kh nng chuyn mng phc tp v s dng truyn dn ting s ha trn v tuyn. Tnh nng cui cng chnh l yu cu i vi

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2G. Cc th d in hnh v cc h thng 2G l: GSM (Global System for Mobile Communications: thng tin di ng ton cu) v cdmaOne (da trn tiu chun TIA IS95). C th ci mt h thng TTD l 3G nu n p ng mt s cc yu cu c ITU ra: Hot ng trong mt trong s cc tn s c n nh cho cc dch v 3G Phi cung cp dy cc dch v s liu mi cho ngi s dng bao gm c a phng tin, c lp vi cng ngh giao din v tuyn Phi h tr truyn dn s liu di ng ti 144 kbps cho cc ngi s dng di ng tc cao v truyn dn s liu ln n 2Mbps (t nht l l thuyt) cho cc ngi s dng c nh hoc di ng tc thp Phi cung cp cc dch v s liu gi (cc dch v khng da trn kt ni CS n mng s liu m da trn dch v mang da trn gi bm sinh) Phi m bo tnh c lp ca mng li vi giao din v tuyn

Mt s h thng 2G ang tin ha n t nht mt phn cc yu cu trn. iu ny dn n mt hu qu khng mong mun: lm sai lch thut ng "cc th h". Chng hn GSM vi h tr s liu knh c phn loi nh h thng 2G thun ty. Khi tng cng thm GPRS (General Packet Radio Service), n tr nn ph hp vi nhiu tiu chun 3G. Dn n n khng hn l 2G cng nh 3G m l loi "gia cc th h", v th h thng GSM c tng cng GPRS hin nay c gi l h thng 2,5G, trong khi thc t vn thuc loi 2G, t nht l t phng din cng ngh truyn dn v tuyn. Hnh 1.1 tng kt cc vn trnh by trn bng cch minh ha cc h thng TTD chnh v qu trnh pht trin ca chng theo ba th h.

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NMT

TACS

AMPS

GSM

TDMA(IS-136)

cdmaOne(IS95-A)

CDPD

PDC/PDC-P

GSM+GPRS

TDMAIS136+GPRS

EDGE/GPRS

CDMA (IS95-B)

WCDMA/HSPA

TD-SCDMA

WCDMA/TDD

WCDMA/FDD

ETSI UMTS/W-CDMA

EDGE tng cng/GPRS

cdma20003x(5MHz)

cdma20001x(1,25MHz)

cdma20001xEV-DO

cdma20001xEV-DV

ARIB WCDMA (Nht)

1985 1989 1995 2001 2003 2004+

1G 2G 2,5G

3G

K hiu: AMPS: Advanced Mobile Phone Service , TACS: Total Access Communication System NMT: Nodic Mobile Telephone, PDC: Personal Digital Cellular: h thng t ong s cc nhn. PDC-P: PDC-Packet, GSM: Global System for Mobile Telecommunications CDPD: Cellular Digital Packet Data, GPRS: General Radio Packet Service EDGE: Enhanced Data Rate for GSM Evolution, WCDMA: Wideband Code Division Multiple Access HSPA: High Speed Paket Access, UMTS: Universal Mobile Telecommunications System cdma20001xEV-DO: cdma20001xEvolution-Data Only, cdma20001xEV-DV: cdma20001xEvolution-Data and Voice FDD: Frequency Division Duplex. TDD: Time Division Duplex Hnh 1.1. L trnh tin ha ca cc h thng thng tin di ng 1.3. KIN TRC GSM GSM l mng thng tin di ng s u tin c xy dng trn phng php a truy nhp TDMA. Mt h thng GSM c t chc thnh ba phn t chnh: MS, h thng con trm gc (BSS: base station subsystem) v h thng con chuyn mch (SS: switching subsystem ) nh trn hnh 1.2.

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SIM

ME

BTS

BTS

BSC

BTS

BTS

BSC

BSS

BSS

VLR HLR AuC EIR

MSC

Mng bo hiu s 7

SMS-GMSC

PTSNISDN

CSPDNPSPDN

SS

Trm di ng(MS)

H thng con trm gc(BSS)

H thng con chuyn mch(SS)

Um Abis A

Hnh 1.2. Kin trc mng GSM

MS cha u cui di ng vi SIM card. SIM l mt thit b an ninh cha tt c cc thng tin cn thit v cc gii thut nhn thc thu bao cho mng. nhn thc thu bao cho mng, SIM cha mt my vi tnh gm CPU v ba kiu nh. ROM c lp trnh cha h iu hnh, chng trnh cho ng dng GSM v cc gii thut an ninh A3 v A8. RAM c s dng thc hin cc gii thut v nh m cho truyn dn s liu. Cc s liu nhy cm nh Ki (kha b mt), IMSI (international mobile station identity: s nhn dng thu bao di ng), cc s quay, cc bn tin ngn, thng tin v mng v v thu bao nh TMSI (temporary mobile station identity: s nhn dng thu bao tm thi), LAI (location area identity: nhn dng vng nh v) c lu trong b nh ROM xa c bng in (EEPROM).

H thng con trm gc (BSS) bao gm mt s trm thu pht gc (BTS: base transceiver station: trm thu pht gc) v mt b iu khin trm gc (BSC: base station controller). BTS iu khin lu lng v tuyn gia MS v chnh n thng qua giao din v tuyn Um. H thng con mng cha trung tm chuyn mch cc dch v di ng (MSC: mobile switching center) thc hin tt c cc ng dng cn thit nh tuyn cuc gi n hoc t cc ngi s dng v cc mng in thai khc nhau nh: ISDN, PSTN. HLR (home location register: b ghi nh v thng tr) mang tt c cc thng tin v thu bao trong vng ca GMSC (gateway MSC: MSC cng) tng ng. VLR (visitor location register: b ghi nh v tm tr) cha cc chi tit tm thi v MS lm khch ti MSC hin thi. N cng cha TMSI. Trung tm nhn thc (AuC: authentication center) c t ti HLR v l mt trong nhng ni pht i cc thng s an ninh quan trng nht v n m bo tt c cc thng s cn thit cho nhn thc v mt m ha gia MS v BTS. TMSI cho php t chi mt k xu tm cch ly trm thng tin v cc ti nguyn c ngi s dng s dng v khng cho k xu theo di v tr ngi s dng. Mc ch ca EIR (equipment identity register: b ghi nhn dng

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thit b) l ghi li nhn dng s my ca thit b di ng chng mt cp my. Ni mt cch khc EIR cha cc s seri my ca tt c cc my di ng v nh du du s my b mt hoc b n cp m h thng s khng cho php. Cc ngi s dng s c nhn dng l en (khng hp l) trng (hp l ) hay xm (b nghi ng).

1.4. KIN TRC GPRS GPRS s dng li mng truy nhp v tuyn ca GSM truyn s liu gi bng cch ghp nhiu khe thi gian vo mt knh truyn. Kin trc ca GPRS c cho trn hnh 1.3.

EIR MSC/VLRSMS-GMSCSMS-IWMSC

HLR/AuC

MT BSS SGSN GGSN Internet

SGSN

Um Gb

Gf Gs Gd Gr Gc

GiGn

Gp

Mng li

TE

Hnh 1.3. Kin trc GPRS MS gm thit b u cui (TE:Terminal Equipment) (my tnh PC cm tay chng hn) v u cui di ng (MT). MS c th hot ng trong ba ch ph thuc vo kh nng ca mng v my di ng. Ch A, c th x l ng thi c khai thc chuyn mch knh ln chuyn mch

gi Ch B, cho php MS hoc ch PS hoc ch CS nhng khng ng

thi c hai ch . Khi MS pht cc gi, nu kt ni CS c yu cu th truyn dn PS t ng c t vo ch treo

Ch C, cho php MS thc hin mi ln mt dch v. Nu MS ch h tr lu lng PS (GPRS) th n hot ng ch C.

Trong BSS, BTS x l c lu lng CS v PS. N chuyn s liu PS n SGSN v

CS n MSC. Ngoi cc tnh nng GSM, HLR cng c s dng xc nh xem thu bao GPRS c a ch IP tnh hay ng v im truy nhp no s dng ni n mng ngoi. i vi GPRS, cc thng tin v thu bao c trao i gia HLR vi SGSN.

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SGSN x l lu lng cc gi IP n v t MS ng nhp vo vng phc v ca n v n cng m bo nh tuyn gi nhn c v gi i t n.

GGSN m bo kt ni vi cc mng chuyn mch gi bn ngoi nh Internet hay cc mng ring khc. Nt kt ni vi mng ng trc GPRS da trn IP. N cng chuyn i tt c cc gi IP v c s dng trong qu trnh nhn thc v trong cc th tc mt m ha..

AuC hot ng ging nh mng GSM. C th l n cha thng tin nhn dng cc ngi c php s dung mng GPRS v v th ngn chn vic s s dng tri php mng. 3GUMTS c xy dng theo ba pht hnh chnh c gi l R3, R4, R5. Trong mng li R3 v R4 bao gm hai min: min CS (Circuit Switch: chuyn mch knh) v min PS (Packet Switch: chuyn mch gi). Vic kt hp ny ph hp cho giai on u khi PS cha p ng tt cc dch v thi gian thc nh thoi v hnh nh. Khi ny min CS s m nhimcc dc v thai cn s liu c truyn trn min PS. R4 pht trin hn R3 ch min CS chuyn sang chuyn mch mm v th ton b mng truyn ti gia cc nt chuyn mch u trn IP. Mng truy nhp ca UMTS c th l TDMA hoc CDMA. Trong chng ny ta ch xt mng truy nhp CDMA cho UMTS. Di y ta xt ba kin trc 3GUMTS ni trn. 1.5. KIN TRC 3G WCDMA UMTS R3 UMTS R3 h tr c kt ni chuyn mch knh ln chuyn mch gi: n 384 Mbps trong min CS v 2Mbps trong min PS. Cc kt ni tc cao ny m bo cung cp mt tp cc dich v mi cho ngi s dng di ng ging nh trong cc mng in thoi c nh v Internet. Cc dch v ny gm: in thoi c hnh (Hi ngh video), m thanh cht lng cao (CD) v tc truyn cao ti u cui. Mt tnh nng khc cng c a ra cng vi GPRS l "lun lun kt ni" n Internet. UMTS cng cung cp thng tin v tr tt hn v v th h tr tt hn cc dch v da trn v tr.

Mt mng UMTS bao gm ba phn: thit b di ng (UE: User Equipment), mng truy nhp v tuyn mt t UMTS (UTRAN: UMTS Terrestrrial Radio Network), mng li (CN: Core Network) (xem hnh 1.4). UE bao gm ba thit b: thit b u cui, thit b di ng v module nhn dng thu bao UMTS (USIM: UMTS Subsscriber Identity Module) . UTRAN gm cc h thng mng v tuyn (RNS: Radio Network System) v mi RNS bao gm RNC (Radio Network Controller) v cc BTS ni vi n. Mng li CN bao gm min chuyn mch knh, chuyn mch gi v HE (Home Environment: Mi trng nh). HE bao gm cc c s d liu: AuC (Authentication Center: Trung tm nhn thc), HLR (Home Location Register: B ghi nh v thng tr) v EIR (Equipment Identity Register: B ghi nhn dng thit b).

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TE

ME

USIM

R

Cu

UE Uu

Nt B

Nt B

Nt B

Nt B

RNC

RNC

UTRAN

Iub

Iu

MSC/VLR GMSC

SGSN GGSN

EIR HLR/AuCIur

E

F D C

HE

Gf Gr Gc

Gn Gi

CN

PSTNISDN

Internet

Min CS

Min PS

Hnh 1.4. Kin trc UMTS 1.5.1. Thit b ngi s dng UE (User Equipment: thit b ngi s dng) l u cui mng UMTS ca ngi s dng. C th ni y l phn h thng c nhiu thit b nht v s pht trin ca n s nh hng ln ln cc ng dng v cc dch v kh dng. Gi thnh gim nhanh chng s to iu kin cho ngi s dng mua thit b ca UMTS. iu ny t c nh tiu chun ha giao din v tuyn v ci t mi tr tu ti cc card thng minh. 1.5.1.1. Cc u cui V my u cui by gi khng ch n thun dnh cho in thoi m cn cung cp cc dch v s liu mi, nn tn cu n c chuyn thnh u cui. Cc nh sn xut chnh a ra rt nhiu u cui da trn cc khi nim mi, nhng trong thc t ch mt s t l c a vo sn xut. Mc d cc u cui d kin khc nhau v kch thc v thit k, tt c chng u c mn hnh ln v t phm hn so vi 2G. L do chnh l tng cng s dng u cui cho nhiu dch v s liu hn v v th u cui tr thnh t hp cu my thoi di ng, modem v my tnh bn tay. u cui h tr hai giao din. Giao din Uu nh ngha lin kt v tuyn (giao din WCDMA). N m nhim ton b kt ni vt l vi mng UMTS. Giao din th hai l giao din Cu gia UMTS IC card (UICC) v u cui. Giao din ny tun theo tiu chun cho cc card thng minh. Mc d cc nh sn xut u cui c rt nhiu tng v thit b, h phi tun theo mt tp ti thiu cc nh ngha tiu chun cc ngi s dng bng cc u cui khc nhau c th truy nhp n mt s cc chc nng c s theo cng mt cch. Cc tiu chun ny gm: Bn phm (cc phm vt l hay cc phm o trn mn hnh)

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ng k mt khu mi Thay i m PIN Gii chn PIN/PIN2 Trnh by IMEI iu khin cuc gi Cc phn cn li cu giao din s dnh ring cho nh thit k v ngi s dng s chn cho mnh u cui da trn hai tiu chun (nu xu th 2G cn ko di) l thit k v giao din. Giao din l kt hp ca kch c v thng tin do mn hnh cung cp (mn hnh nt chm), cc phm v menu. 1.5.1.2. UICC UMTS IC card l mt card thng minh. iu m ta quan tm n n l dung lng nh v tc b x l do n cung cp. ng dng USIM chy trn UICC. 1.5.1.3. USIM Trong h thng GSM, SIM card lu gi thng tin c nhn (ng k thu bao) ci cng trn card. iu ny thay i trong UMTS, Modul nhn dng thu bao UMTS c ci nh mt ng dng trn UICC. iu ny cho php lu nhiu ng dng hn v nhiu ch k (kha) in t hn cng vi USIM cho cc mc ch khc (cc m truy nhp giao dch ngn hng an ninh). Ngoi ra c th c nhiu USIM trn cng mt UICC h tr truy nhp n nhiu mng. USIM cha cc hm v s liu cn nhn dng v nhn thc thu bao trong mng UMTS. N c th lu c bn sao h s ca thu bao. Ngi s dng phi t mnh nhn thc i vi USIM bng cch nhp m PIN. iu ny m bo rng ch ngi s dng ch thc mi c truy nhp mng UMTS. Mng s ch cung cp cc dch v cho ngi no s dng u cui da trn nhn dng USIM c ng k. 1.5.2. Mng truy nhp v tuyn UMTS UTRAN (UMTS Terrestrial Radio Access Network: Mng truy nhp v tuyn mt t UMTS) l lin kt gia ngi s dng v CN. N gm cc phn t m bo cc cuc truyn thng UMTS trn v tuyn v iu khin chng. UTRAN c nh ngha gia hai giao din. Giao din Iu gia UTRAN v CN, gm hai phn: IuPS cho min chuyn mch gi v IuCS cho min chuyn mch knh; giao din Uu gia UTRAN v thit b ngi s dng. Gia hai giao din ny l hai nt, RNC v nt B.

8


1.5.2.1. RNC RNC (Radio Network Controller) chu trch nhim cho mt hay nhiu trm gc v iu khin cc ti nguyn ca chng. y cng chnh l im truy nhp dch v m UTRAN cung cp cho CN. N c ni n CN bng hai kt ni, mt cho min chuyn mch gi (n GPRS) v mt n min chuyn mch knh (MSC). Mt nhim v quan trng na ca RNC l bo v s b mt v ton vn. Sau th tc nhn thc v tha thun kha, cc kho bo mt v ton vn c t vo RNC. Sau cc kha ny c s dng bi cc hm an ninh f8 v f9. RNC c nhiu chc nng logic ty thuc v vic n phc v nt no. Ngi s dng c kt ni vo mt RNC phc v (SRNC: Serving RNC). Khi ngi s dng chuyn vng n mt RNC khc nhng vn kt ni vi RNC c, mt RNC tri (DRNC: Drift RNC) s cung cp ti nguyn v tuyn cho ngi s dng, nhng RNC phc v vn qun l kt ni ca ngi s dng n CN. Chc nng cui cng ca RNC l RNC iu khin (CRNC: Control RNC). Mi nt B c mt RNC iu khin chu trch nhim cho cc ti nguyn v tuyn ca n. 1.5.2.2. Nt B Trong UMTS trm gc c gi l nt B v nhim v ca n l thc hin kt ni v tuyn vt l gia u cui vi n. N nhn tn hiu trn giao din Iub t RNC v chuyn n vo tn hiu v tuyn trn giao din Uu. N cng thc hin mt s thao tc qun l ti nguyn v tuyn c s nh "iu khin cng sut vng trong". Tnh nng ny phng nga vn gn xa; ngha l nu tt c cc u cui u pht cng mt cng sut, th cc u cui gn nt B nht s che lp tn hiu t cc u cui xa. Nt B kim tra cng sut thu t cc u cui khc nhau v thng bo cho chng gim cng sut hoc tng cng sut sao cho nt B lun thu c cng sut nh nhau t tt c cc u cui. . 1.5.3. Mng li Mng li (CN) c chia thnh ba phn, min PS, min CS v HE. Min PS m bo cc dch v s liu cho ngi s dng bng cc kt ni n Internet v cc mng s liu khc v min CS m bo cc dch v in thai n cc mng khc bng cc kt ni TDM. Cc nt B trong CN c kt ni vi nhau bng ng trc ca nh khai thc, thng s dng cc cng ngh mng tc cao nh ATM v IP. Mng ng trc trong min CS s dng TDM cn trong min PS s dng IP. 1.5.3.1. SGSN

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SGSN (SGSN: Serving GPRS Support Node: nt h tr GPRS phc v) l nt chnh ca min chuyn mch gi. N ni n UTRAN thng qua giao din IuPS v n GGSN thng quan giao din Gn. SGSN chu trch nhim cho tt c kt ni PS ca tt c cc thu bao. N lu hai kiu d liu thu bao: thng tin ng k thu bao v thng tin v tr thu bao. S liu thu bao lu trong SGSN gm: IMSI (International Mobile Subsscriber Identity: s nhn dng thu bao di ng

quc t) Cc nhn dng tm thi (P-TMSI: Packet- Temporary Mobile Subsscriber Identity:

s nhn dng thu bao di ng tm thi gi) Cc a ch PDP (Packet Data Protocol: Giao thc s liu gi) S liu v tr lu trn SGSN: Vng nh tuyn thu bao (RA: Routing Area) S VLR Cc a ch GGSN ca tng GGSN c kt ni tch cc 1.5.3.2. GGSN GGSN (Gateway GPRS Support Node: Nt h tr GPRS cng) l mt SGSN kt ni vi cc mng s liu khc. Tt c cc cuc truyn thng s liu t thu bao n cc mng ngoi u qua GGSN. Cng nh SGSN, n lu c hai kiu s liu: thng tin thu bao v thng tin v tr. S liu thu bao lu trong GGSN: IMSI Cc a ch PDP S liu v tr lu trong GGSN: a ch SGSN hin thu bao ang ni n GGSN ni n Internet thng qua giao din Gi v n BG thng qua Gp. 1.5.3.3. BG BG (Border Gatway: Cng bin gii) l mt cng gia min PS ca PLMN vi cc mng khc. Chc nng cu nt ny ging nh tng la ca Internet: m bo mng an ninh chng li cc tn cng bn ngoi. 1.5.3.4. VLR

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VLR (Visitor Locatoin Register: b ghi nh v tm tr) l bn sao cu HLR cho mng phc v (SN: Serving Network). D liu thu bao cn thit cung cp cc dch v thu bao c copy t HLR v lu y. C MSC v SGSN u c VLR ni vi chng. S liu sau y c lu trong VLR: IMSI MSISDN TMSI (nu c) LA hin thi ca thu bao MSC/SGSN hin thi m thu bao ni n

Ngoi ra VLR c th lu gi thng v cc dch v m thu bao c cung cp. C SGSN v MSC u c thc hin trn cng mt nt vt l vi VLR v th

c gi l VLR/SGSN v VLR/MSC. 1.5.3.5. MSC MSC thc hin cc kt ni CS gia u cui v mng. N thc hin cc chc nng bo hiu v chuyn mch cho cc thu bao trong vng qun l ca mnh. Chc nng ca MSC trong UMTS ging chc nng MSC trong GSM, nhng n c nhiu kh nng hn. Cc kt ni CS c thc hin trn giao din CS gia UTRAN v MSC. Cc MSC c ni n cc mng ngoi qua GMSC. 1.5.3.6. GMSC GMSC c th l mt trong s cc MSC. GMSC chu trch nhim thc hin cc chc nng nh tuyn n vng c MS. Khi mng ngoi tm cch kt ni n PLMN cu mt nh khai thc, GMSC nhn yu cu thit lp kt ni v hi HLR v MSC hin thi qun l MS. 1.5.3.7. Mi trng nh Mi trng nh (HE: Home Environment) lu cc h s thu bao cu hng khai thc. N cng cung cp cho cc mng phc v (SN: Serving Network) cc thng tin v thu bao v v cc cn thit nhn thc ngi s dng v tnh cc cho cc dch v cung cp. Trong phn ny ta s lit k cc dch v c cung cp v cc dch v b cm.

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Thanh ghi nh v thng tr (HLR) HLR l mt c s d liu c nhim v qun l cc thu bao di ng. Mt mng di ng c th cha nhiu HLR ty thuc vo s lng thu bao, dung lng ca tng HLR v t chc bn trong mng. C s d liu ny cha IMSI (International Mobile Subsscribern Identity: s nhn dng thu bao di ng), t nht mt MSISDN (Mobile Station ISDN: s thu bao cso trong danh b in thai) v t nht mt a ch PDP(Packet Data Protocol: Giao thc s liu gi). C IMSI v MSISDN c th s dng lm kho truy nhp n cc thng tin c lu khc. nh tuyn v tnh cc cc cuc gi, HLR cn lu gi thng tin v SGSN v VLR no hin ang chu trch nhim thu bao. Cc dch v khc nh chuyn hng cuc gi, tc s liu v th thoi cng c trong danh sch cng vi cc hn ch dch v nh cc hn ch chuyn mng. HLR v AuC l hai nt mng logic, nhng thng c thc hin trong cng mt nt vt l. HLR lu gi mi thng tin v ngi s dng v ng k thu bao. Nh: thng tin tnh cc, cc dch v no c cung cp v cc dch v no b t chi v thng tin chuyn hng cuc gi. Nhng thng tin quan trong nht l hin VLR v SGSN no ang ph trch ngi s dng. Trung tm nhn thc (AuC) AUC (Authentication Center) lu gi ton b s liu cn thit nhn thc, mt m ha v bo v s ton vn thng tin cho ngi s dng. N lin kt vi HLR v c thc hin cng vi HLR trong cng mt nt vt l. Tuy nhin cn m bo rng AuC ch cung cp thng tin v cc vect nhn thc (AV: Authetication Vector) cho HLR. AuC lu gi kha b mt chia s K cho tng thu bao cng vi tt c cc hm to kha t f0 n f5. N to ra cc AV, c trong thi gian thc khi SGSN/VLR yu cu hay khi ti x l thp, ln cc AV d tr. B ghi nhn thc thit b (EIR) EIR (Equipment Identity Register) chu trch nhim lu cc s nhn dng thit b di ng quc t (IMEI: International Mobile Equipment Identity). y l s nhn dng duy nht cho thit b u cui. C s d liu ny c chia thnh ba danh mc: danh mc trng, xm v en. Danh mc trng cha cc s IMEI c php truy nhp mng. Danh mc xm cha IMEI ca cc u cui ang b theo di cn danh mc en cha cc s IMEI cu cc u cui b cm truy nhp mng. Khi mt u cui c thng bo l b mt cp, IMEI ca n s b t vo danh mc en v th n b cm truy

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nhp mng. Danh mc ny cng c th c s dng cm cc seri my c bit khng c truy nhp mng khi chng khng hot ng theo tiu chun. 1.5.4. Cc mng ngoi Cc mng ngoi khng phi l b phn ca h thng UMTS, nhng chng cn thit m bo truyn thng gia cc nh khai thc. Cc mng ngoi c th l cc mng in thoi nh: PLMN (Public Land Mobile Network: mng di ng mt t cng cng), PSTN (Public Switched Telephone Network: Mng in thoi chuyn mch cng cng), ISDN hay cc mng s liu nh Internet. Min PS kt ni n cc mng s liu cn min CS ni n cc mng in thoi. 1.5.5. Cc giao din Vai tr cc cc nt khc nhau cu mng ch c nh ngha thng qua cc giao din khc nhau. Cc giao din ny c nh nghi cht ch cc nh sn xut c th kt ni cc phn cng khc nhau ca h. 1.5.5.1. Uu Giao din Uu l WCDMA, giao din v tuyn c nh ngha cho UMTS. Giao din ny nm gia nt B v u cui. 1.5.5.2. Iu Giao din Iu kt ni CN v UTRAN. N gm ba phn, IuPS cho min chuyn mch gi, IuCS cho min chuyn mch knh v IuBC cho min qung b. CN c th kt ni n nhiu UTRAN cho c giao din IuCS v IuPS. Nhng mt UTRAN ch c th kt ni n mt im truy nhp CN. 1.6. KIN TRC 3G WCDMA UMTS R4.

Hnh 1.5 cho thy kin trc c s ca 3G UMTS R4. S khc nhau c bn gia R3 v R4 l ch khi ny mng li l mng phn b v chuyn mch mm. Thay cho vic c cc MSC chuyn mch knh truyn thng nh kin trc trc, kin trc chuyn mch phn b v chuyn mch mm c a vo.

V cn bn, MSC c chia thnh MSC server v cng cc phng tin (MGW: Media Gateway). MSC cha tt c cc phn mm iu khin cuc gi, qun l di ng c mt MSC tiu chun. Tuy nhin n khng cha ma trn chuyn mch. Ma trn

13


chuyn mch nm trong MGW c MSC Server iu khin v c th t xa MSC Server.

HSS/HLR

Sniffer Servermoni toring/analysis

Sniffer Servermoni toring/ana lysis

SS7

PSTNSniffer Servermoni to ring/analysis Sniffer Servermoni toring/analysi s

Internet

Iub

PCM

RNC

GGSNSGSN

RNC

Iub

Iur

Gi(IP)

GMSC Server

IP

H248/IP

RTP/IPMGW

Nt B

Nt B

SS7 GW

MSC Server

H248/IP

Gn(GTP/IP)Iu-ps

SS7 GW

Iu-cs (iukhin)

Iu-cs(Vt mang)

MGW

Hnh 1.5. Kin trc mng phn b ca pht hnh 3GPP Release 4

Bo hiu iu khin cc cuc gi chuyn mch knh c thc hin gia RNC v MSC Server. ng truyn cho cc cuc gi chuyn mch knh c thc hin gia RNC v MGW. Thng thng MGW nhn cc cuc gi t RNC v nh tuyn cc cuc gi ny n ni nhn trn cc ng trc gi. Trong nhiu trng hp ng trc gi s dng Giao thc truyn ti thi gian thc (RTP: Real Time Transport Protocol) trn Giao thc Internet (IP). T hnh 1.5 ta thy lu lng s liu gi t RNC i qua SGSN v t SGSN n GGSN trn mng ng trc IP. C s liu v ting u c th s dng truyn ti IP bn trong mng li. y l mng truyn tai hon ton IP.

Ti ni m mt cuc gi cn chuyn n mt mng khc, PSTN chng hn, s c mt cng cc phng tin khc (MGW) c iu khin bi MSC Server cng (GMSC server). MGW ny s chuyn ting thoi c ng gi thnh PCM tiu chun a n PSTN. Nh vy chuyn i m ch cn thc hin ti im ny. th d, ta gi thit rng nu ting giao din v tuyn c truyn ti tc 12,2 kbps, th tc ny ch phi chuyn vo 64 kbps MGW giao tip vi PSTN. Truyn ti kiu ny cho php tit kim ng k rng bng tn nht l khi cc MGW cch xa nhau.

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Giao thc iu khin gia MSC Server hoc GMSC Server vi MGW l giao thc ITU H.248. Giao thc ny c ITU v IETF cng tc pht trin. N c tn l iu khin cng cc phng tin (MEGACO: Media Gateway Control). Giao thc iu khin cuc gi gia MSC Server v GMSC Server c th l mt giao thc iu khin cuc gi bt k. 3GPP ngh s dng (khng bt buc) giao thc iu khin cuc gi c lp vt mang (BICC: Bearer Independent Call Control) c xy dng trn c s khuyn ngh Q.1902 ca ITU.

Trong nhiu trng hp MSC Server h tr c cc chc nng ca GMSC Server. Ngoi ra MGW c kh nng giao din vi c RAN v PSTN. Khi ny cuc gi n hoc t PSTN c th chuyn ni ht, nh vy c th tit kim ng k u t.

lm th d ta xt trng hp khi mt RNC c t ti thnh ph A v c iu khin bi mt MSC t ti thnh ph B. Gi s thu bao thnh ph A thc hin cuc gi ni ht. Nu khng c cu trc phn b, cuc gi cn chuyn t thnh ph A n thnh ph B (ni c MSC) u ni vi thu bao PSTN ti chnh thnh ph A. Vi cu trc phn b, cuc gi c th c iu khin ti MSC Server thnh ph B nhng ng truyn cc phng tin thc t c th vn thnh ph A, nh vy gim ng k yu cu truyn dn v gi thnh khai thc mng.

T hnh 1.5 ta cng thy rng HLR cng c th c gi l Server thu bao ti nh (HSS: Home Subscriber Server). HSS v HLR c chc nng tng ng, ngai tr giao din vi HSS l giao din trn c s truyn ti gi (IP chng hn) trong khi HLR s dng giao din trn c s bo hiu s 7. Ngoi ra cn c cc giao din (khng c trn hnh v) gia SGSN vi HLR/HSS v gia GGSN vi HLR/HSS.

Rt nhiu giao thc c s dng bn trong mng li l cc giao thc trn c s gi s dng hoc IP hoc ATM. Tuy nhin mng phi giao din vi cc mng truyn thng qua vic s dng cc cng cc phng tin. Ngoi ra mng cng phi giao din vi cc mng SS7 tiu chun. Giao din ny c thc hin thng qua cng SS7 (SS7 GW). y l cng m mt pha n h tr truyn ti bn tin SS7 trn ng truyn ti SS7 tiu chun, pha kia n truyn ti cc bn tin ng dng SS7 trn mng gi ( IP chng hn). Cc thc th nh MSC Server, GMSC Server v HSS lin lc vi cng SS7 bng cch s dng cc giao thc truyn ti c thit k c bit mang cc bn tin SS7 mng IP. B giao thc ny c gi l Sigtran.

1.7. KIN TRC 3G WCDMA UMTS R5

Bc pht trin tip theo ca UMTS l a ra kin trc mng a phng tin IP (hnh 1.6). Bc pht trin ny th hin s thay i ton b m hnh cuc gi. y c ting v s liu c x l ging nhau trn ton b ng truyn t u cui ca ngi s dng n ni nhn cui cng. C th coi kin trc ny l s hi t ton din ca ting v s liu.

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SS7

HSS/HLR

Sniffer Servermonitoring/analysis


SS7

PSTN



Internet

Iub

Gr

PCM

RNC

GGSNSGSNRNC

Iub

Iur

Gn Gi

Gi

MRF

T-SGW

Mc

Mg

Mr

Gi

Cx

CSCF R-SGW

Chc nng iu khintrng thi cuc gi

(CSCF)

Chc nng iu khincng mi trng

(MGCF)

MGW

Node B

Node B

Cx

Iu

Hnh 1.6. Kin trc mng a phng tin IP ca 3GPP T hnh 1.6 ta thy ting v s liu khng cn cc giao din cch bit; ch c mt

giao din Iu duy nht mang tt c phng tin. Trong mng li giao din ny kt cui ti SGSN v khng c MGW ring.

Ta cng thy c mt s phn t mng mi nh: Chc nng iu khin trng thi kt ni (CSCF: Connection State Control Function), Chc nng ti nguyn a phng tin (MRF: Multimedia Resource Function), chc nng iu khin cng cc phng tin (MGCF: Media Gateway Control Function), Cng bo hiu truyn ti (T-SGW: Transport Signalling Gateway) v Cng bo hiu chuyn mng (R-SGW: Roaming Signalling Gateway).

Mt nt quan trng ca kin trc ton IP l thit b ca ngi s dng c tng cng rt nhiu. Nhiu phn mm c ci t UE. Trong thc t, UE h tr giao thc khi u phin (SIP: Session Initiation Protocol). UE tr thnh mt tc nhn ca ngi s dng SIP. Nh vy, UE c kh nng iu khin cc dch v ln hn trc rt nhiu.

CSCF qun l vic thit lp , duy tr v gii phng cc phin a phng tin n v t ngi s dng. N bao gm cc chc nng nh: phin dch v nh tuyn. CSCF hot ng nh mt i din Server /h tch vin.

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SGSN v GGSN l cc phin bn tng cng ca cc nt c s dng GPRS v UMTS R3 v R4. im khc nhau duy nht l ch cc nt ny khng ch h tr dch v s liu gi m c dch v chuyn mch knh (ting chng hn). V th cn h tr cc kh nng cht lng dch v (QoS) hoc bn trong SGSN v GGSN hoc t nht cc Router kt ni trc tip vi chng.

Chc nng ti nguyn a phng tin (MRF) l chc nng lp cu hi nghi c s dng h tr cc tnh nng nh t chc cuc gi nhiu pha v dch v hi ngh .

Cng bo hiu truyn ti (T-SGW) l mt cng bo hiu SS7 m bo tng tc SS7 vi cc mng tiu chun ngoi nh PSTN. T-SGW h tr cc giao thc Sigtran. Cng bo hiu chuyn mng (R-SGW) l mt nt m bo tng tc bo hiu vi cc mng di ng hin c s dng SS7 tiu chun. Trong nhiu trng hp T-SGW v R-SGW cng tn ti trn cng mt nn tng.

MGW thc hin tng tc vi cc mng ngoi mc ng truyn a phng tin. MGW kin trc mng ca UMTS R5 c chc nng ging nh R4. MGW c iu khin bi Chc nng cng iu khin cc phng tin (MGCF). Giao thc iu khin gia cc thc th ny l ITU-T H.248.

MGCF cng lin lc vi CSCF. Giao thc c chn cho giao din ny l SIP. Cn lu rng pht hnh cu trc ton IP ca R5 l mt tng cng ca mng

R3 hoc R4. N a thm vo mt vng mi trong mng l vng a phng tin IP (IM: IP Multimedia). Vng mi ny cho php mang c ting v s liu trn IP trn ton tuyn ni n my cm tay. Vng ny s dng vng chuyn mch gi PS cho mc ch truyn ti: s dng SGSN, GGSN, Gn, Gi ... l cc nt v giao din thuc vng PS.

1.8. KIN TRC CDMA2000 Mng gi ca cdma2000 l mng kt hp vi mng chuyn mch knh cdma2000 s dng bo hiu IS-41. Mng IP bao gm PCF (Packet Control Function: Chc nng iu khin gi), PDSN (Packet Data Serving Node: Nt phc v s liu gi), HA v cc server AAA (Authentication, Authorization and Account: Nhn thc, trao quyn v thanh ton). i vi dch v IP n gin (Simple IP), vic ngi s dng chuyn t vng phc v ca mt PDSN ny sang vng phc v ca mt PDSN khc s dn n s thay i phin s liu v a ch IP mi s c n nh bi PDSN mi. i vi dch v MIP (Mobile IP), phin s liu c th ko di trn nhiu PDSN chng no ngi s dng vn duy tr cc rng buc di ng ti HA v cha ht thi hn hiu lc ca ng k (hoc ti ng k) (a ch IP ny vn khng i). Kin trc ca cdma 2000 c cho hnh 1.7. Kin trc 1.6 c trnh by cho trng hp MIP. i vi dch v IP n gin, kin trc trn hnh 1.6 s khng c HA v FA..

17


Hnh 1.7. Kin trc ca cdma 2000 1.8.1. MS MS thc hin c dch v CS ln MIP. i vi MIP MS phi: H tr PPP C th hot ng nh mt MIP MN, h tr h lnh FA v NAI Tng tc vi RAN v mng li nhn c cc ti nguyn mng cho vic trao

i gi Ghi nh trng thi ca cc ti nguyn v tuyn (tch cc, ch, ng) 1.8.2. Mng truy nhp v tuyn RAN

Mng truy nhp v tuyn RAN gm cc BTS v cc BSC. BTS iu khin lu lng v tuyn gia MS v chnh n thng qua giao din v tuyn. Nhiu BTS v c th ni n mt BSC. T hp cc BTS cng vi mt BSC m chng ni n c go l BSS (Base station Subsystem: h thng con trm gc). Cc BSS cho php truy nhp c dch v CS v PS. h tr truy nhp dchv PS, BSS c thm khi chc iu khin gi: PCF (Packet Control Function: Chc nng iu khin gi). Khi cc gi c gi n mt MS, nhng cha th ni n MS, PCF nh m cc gi ny v yu cu RAN tm gi MS. N cng thu thp v gi thng tin thanh ton n PDSN. PCF ni BSC vi PDSN thc hin chuyn giao. Trong tiu chun tng tc (IOS: Inter-Operability Standards) 3GPP2 A.S00001, PCF ni n BSC thng qua giao din m A8/A9. Thng thng trong cc sn phm thng mi, PCF c thc hin nh l mt b phn ca BSC vi giao din ring.

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Cdma2000 BSC c qun l ti nguyn v tuyn (RRM: Radio Resource Management), qun l di ng (MM: Mobility Management) v cc kt ni n MSC. N m bo truyn cc gi s liu khng qua codec ting.

Ngoi cc nhim v h tr dch v CS thng thng, RAN cn h tr cc dch v PS sau: Chuyn i tham kho nhn dng client di ng vo mt nhn dng lin kt duy

nht thng tin vi PDSN Nhn thc MS cho php truy nhp dch v Qun l kt ni lp vt l n client di ng Duy tr trng thi cho php kt ni i vi dch v gi gia mng truy nhp v

tuyn v MS Nh m cc gi n t PDSN, khi cc ti nguyn v tuyn cha c hoc cha

h tr dng gi t PDSN Chuyn tip cc gi gia MS v PDSN 1.8.3. Mng nh cung cp dch truy nhp khch Mng nh cung cp dch v truy nhp khch bao gm cc phn t mng li thc hin nhim v chuyn mch knh nh: MSC/VLR v cc phn t mng li thc chuyn mch gi nh: PDSN. MSC s dng IS-41 MSC v c ni n BSC thng qua giao din A1 (cho bo hiu) v giao din A2 (cho lu lng). MSC thc hin cc chc nng chuyn mch thoi v cc chc nng di ng ca h thng. PDSN thc hin cc chc nng chuyn mch gi v cc chc nng di ng ca h thng. PDSN ni n PCF thng qua cc giao din m A8/A9. Ngoi ra h tr dch v PS mng ny c cha mt AAA server a phng lm nhim v nhn thc.

VLR cha cc chi tit tm thi v MS lm khch ti MSC hin thi. N cng cha TMSI. 1.8.3.1. HLR/AuC

HLR mang tt c cc thng tin v thu bao trong vng ca GMSC tng ng. Trung tm nhn thc (AuC) c t ti HLR v l mt trong nhng ni pht i

thng s an ninh quan trng nht v n m bo tt c cc thng s cn thit cho nhn thc v mt m ha gia MS v BTS. Nh m cc gi khi ti nguyn v tuyn cha c hoc khng h tr dng

gi n mng 1.8.3.2. Cc server AAA nh, khch v mi gii

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Cc dch v nhn thc, trao quyn v thanh ton (AAA: Authentication, Authorization and Account) c th c m bo bi giao thc RADIUS (Remote Authentication Dial-in Uer Service: Dch v ngi s dng quay s nhn thc t xa) hoc giao thc DIAMETER. Lc u mng cdma2000 chn giao thc RADIUS, nn giao thc ny c s dng rng ri. Trong chng ny ta ch xt cc dch v AAA s dng RADIUS. Cc AAA Server m bo chuyn vng. AAA server t trong mng IP nh c gi l AAA server nh. AAA server trong mng ca nh cung cp dch v khch c gi l AAA server khch. AAA server nh cha h s thu bao cu ngi s dng, cn AAA server khch ch cha thng tin tm thi lin quan n cc phin ang c s dng bi ngi s dng. H s c th cha thng tin v ng k QoS v thng tin ny c truyn n PDSN. PDSN c th s dng thng tin ny trao quyn truy nhp n mt s dch v hoc cp pht cc ti nguyn da trn cc yu cu v QoS. AAA server mi gii l mt server trung gian, n c cc quan h an ninh vi cc AAA server khch v nh. N c s dng chuyn tip cc bn tin AAA mt cch an ninh gia mng nh cung cp dch v truy nhp trung gian v mng IP nh. Mt mng c th c hoc khng c AAA server mi gii. C th tng kt cc yu cu i vi AAA nh sau: Nhn thc v trao quyn cho mt NAI ca ngi s dng trong mi trng

chuyn vng. NAI nhn c qua CHAP (i vi dch v PPP truyn thng) hay FAC (FA Challenge: h lnh FA) (i vi dch v MIP). FAC thng c tnh ton ph hp vi CHAP

Truyn ti cc thuc tnh s liu v tuyn t mng nh n mng phc v (thng dng h s ngi s dng)

Mt m ha hoc k mt hay nhiu AVP trong cc bn tin AAA gia mng nh, mng khch hay mt mi gii qua nhiu chng AAA server

H tr mt c ch truyn ti AAA tin cy: C ch ny c th ch cho mt ng dng AAA rng bn tin c chuyn n

ng dng ng cp tip theo hay rng xy ra mt thi gian tm ngng Pht li c iu khin bi c ch truyn ti AAA tin cy ny ch khng phi

cc giao thc thp hn (TCP chng hn) Ngay c khi bn tin cn chuyn hay cc ty chn hoc ng ngha ca bn tin

khng ph hp vi giao thc AAA, c ch truyn ti vn bo nhn rng pha ng cp nhn c bn tin. Tuy nhin nu bn tin khng qua c nhn thc, n s khng c bo nhn

Bo nhn c th c gi cng vi cc bn tin AAA C ch truyn ti tin cy phi c kh nng pht hin cc s c im lng ca ng

cp AAA hay ng truyn n ng cp AAA ny qun l s c

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Truyn ti mt chng nhn s trong mt bn tin AAA gim thiu s ln truyn vng lin quan n cc giao dch AAA. Lu : yu cu ny ch p dng cho cc ng dng AAA ch khng cho cc MS

H tr chng pht li v cc kh nng chng t chi cho tt c cc bn tin trao quyn v thanh ton. Giao thc AAA phi m bo kh nng cho cc bn tin thanh ton ph hp vi cc bn tin trao quyn trc

H tr thanh ton thng qua dn xp hai pha v thng qua cc server mi gii m bo cch vit thanh ton khc nhau gia mng phc v v mng nh. y l mt tha thun r rng rng nu mng ring hay ISP nh nhn thc MS yu cu dch v, th mng ring hay mng ISP nh ny cng chp nhn cc tnh cc vi nh cung cp dch v nh hay mi gii. Phi m bo thanh ton thi gian thc

m bo an ninh gia cc AAA server, gia AAA server v PDSN hay HA thng qua an ninh IP.

1.8.3.3. Nt phc v s liu gi Nt phc v s liu gi (PDSN: Packet Data Serving Node) l mt phn t mng neo nm bn trong mng khch v thc hin nhiu chc nng cho vai tr neo ny. i vi dch v MIP, n m bo chc nng FA theo c t RFC 2002. FA l mt router v n m bo cc dch v nh tuyn n mt MS trong mng khch. i vi c MIP v IP n gin, PDSN m bo kt ni lp lin kt s liu n MS bng cch s dng giao thc im n im (PPP: Point-to-Point Protocol). PDSN c ni n PCF thng qua giao din A10/A11 (giao din R-P), A10 s dng cho s liu ca ngi s dng cn A11 s dng cho cc bn tin iu khin. N cung cp mt lin kt gia a ch lp lin kt TTD vi a ch IP ca mt MS. a ch lp lin kt bao gm s nhn dng MS (IMSI chng hn) v nhn dng kt ni MS (mt thng s phn bit cc phin trn mt MS). PDSN cng hot ng nh mt RADIUS client v n truyn thng tin nhn thc n AAA server khch. N cng thu thp s liu thanh tan t PCF, lp tng quan cho s liu ny, to ra thng tin thanh ton v chuyn n n AAA server khch. C th tng kt cc yu cu i vi PDSN nh sau: Thit lp, duy tr v kt cui lp lin kt n client di ng Khi u nhn thc, trao quyn v thanh tan cho client di ng Truyn tunnel (an ninh ty chn) s dng an ninh IP n tc nhn nh Nhn cc thng s dch v t AAA cho clien di ng Thu thp s liu v mc s dng cho mc ch thanh ton chuyn cc s

liu nh n AAA nh tuyn cc gi n cc mng s liu ngoi hay n HA trong trng hp

truyn tunnel ngc

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Chuyn i a ch nh v a ch HA n mt nhn dng lp lin kt duy nht thng tin vi mng v tuyn

1.8.3.4. Tc nhn nh MIP HA l mt router t ti mng IP nh ca MS. N ng k PDSN /FA cho mt MS. ng k PDSN cho MS c thc hin bng CoA, y l mt a ch IP cu PDSN. Khi MS khng nm trong mng nh, HA nhn cc gi gi n MS trn lin kt nh, ng bao chng vo mt tiu IP khc v truyn tunnel chng n PDSN. Cc yu cu i vi HA: Duy tr ng k ca ngi s dng v chuyn cc gi n PDSN Thit lp tunnel (an ninh IP ty chn) n PDSN/FA H tr n nh a ch HA ng n nh a ch nh ng (ty chn) cho MS. n nh a ch nh c th c

thc hin t cc pun (t hp) a ch c lp cu hnh ti ch, thng qua DHCP server hay t AAA server

1.8.4. Cc dch v s liu gi trong cdma2000 1.8.4.1. IP n gin c im ca IP n gin l n khng h tr di ng bn ngoi PDSN phc v. Mng ny ch m bo dch v nh tuyn IP n im nhp mng hin thi (PDSN). iu ny ging nh dch v ca nh cung cp dch v Internet quay s. Mt MS c th chuyn vng t mt RAN ny n mt RAN khc s dng th tc cp nht v tr, nhng khi mt phin c thit lp vi mt PDSN, MS khng th chuyn giao phin ny n mt PDSN khc. PPP c s dng m bo giao thc lin kt s liu gia ngi s dng v PDSN. PDSN n nh mt a ch IP ng cho cho MS trong giai on IPCP (IP Coltrol Protocol) ca PPP. Giao din A10/A11 c s dng m bo truyn tunnel lu lng v chuyn giao ni PDSN. Ngi s dng duy tr a ch IP ca mnh v s dng kt ni IP chng no vn cn nm trong vng phc v ca PDSN phc v. Mng cng c th h tr dch v mng ring o (VPN: Virtual Private Network) khi b sung thm phn mm cho MS. Nhn thc ngi s dng c thc hin bng giao thc nhn thc mt khu (PAP: Password Authentication Protocol) v giao thc nhn thc bt tay h lnh (CHAP: Challenge Handshake Authentication Protocol). PDSN hat ng nh mt AAA (RADIUS) client, n truyn i thng tin nhn thc ngi s dng CHAP hay PAP. PAP l dng nhn thc c s nht, trong tn ngi s dng v mt khu c ngi ny gi i v c mng so snh vi mt bng cha cp tn-mt khu. im yu ca PAP l c tn ngi s dng v mt khu u truyn dng khng c mt 22


m. CHAP loi b c im yu ny bng cch gi n MS mt kho mt m ha tn ngi s dng v mt khu. Trong CHAP, trc ht mng gi i mt bn tin h lnh n MS. MS tr li bng mt gi tr nhn c bng cch s dng kha ni trn. Nu cc gi tr ny trng nhau, th ngi s dng c nhn thc. Nhn thc ngi s dng ch l ty chn trong IP n gin. Mt ngi s dng c th c lp cu hnh cho php MS nhn c dch v IP n gin m khng cn CHAP hoc PAP. IP n gin h tr nn tiu v ti tin theo tiu chun TIA/EIA/IS-835. Nn tiu TCP/IP Van Jacobson cng c h tr theo tiu chun RFC 1144. Giao thc iu khin nn PPP cng c ty chn h tr. Giao thc ny c s dng m phn mt gii thut nn ti tin PPP. 1.8.4.2. MIP Dch v MIP m bo di ng hon ton cho mt ngi s dng. PDSN hot ng nh mt FA. Mi ngi s dng c n nh mt HA trong mng nh ca mnh. MS c n nh mt a ch IP c gi l a ch nh trong cng mt mng con nh HA. MS s dng CoA (a ch IP cu FA) ng k vi HA. ng k ny buc HA phi thc hin ARP (Address Resolution Protocol: Giao thc phn gii a ch) y thc trn mng con nh v bt u nhn tt c cc gi c chuyn n theo a ch nh cu MS. HA cng to lp mt rng buc gia a ch nh ca MS v CoA c quy nh trong yu cu ng k. Khi HA nhn c s liu gii n cho MS, n hng s liu ny n FA theo CoA v FA chuyn s liu ny n MS. Cc gi hng n MS c truyn tunnel bng cch s dng truyn tunnel IP trong IP n a ch CoA. Truyn tunnel IP trong IP c c t trong RFC 2003. MIP cho php ni n MS khng ph thuc vo vic n ang u trong mng cng cng hoc mng ring. iu duy nht cn thit l CoA v HA phi c a ch nh tuyn ton cu. Trong trng hp truy nhp mng ring, MS s dng truyn tunnel ngc qua FA gi s liu n mng ring. Ging nh IP n gin, giao thc lin kt s liu gia MS v PDSN c m bo bi PPP. Nu PDSN nhn c mt gi cho MS khi phin PPP khng c thit lp, PDSN loi b gi ny v gi i mt gi thng bo khng th gi n ni nhn ICMP (Internet Control Message Protocol: Giao thc bn tin iu khin). Mt phin PPP c th h tr nhiu a ch nh IP v th ch php nhiu ng dng trn mt MS. Bo hiu MIP c trao i trn cc knh lu lng trn giao din v tuyn v th khng s dng hiu qu ti nguyn qu gi ca v tuyn. Mt s ci thin c p dng so vi giao thc MIP c s truyn bo hiu hiu xut hn. Mt trong cc ci thin ny l PDSN s khng pht qung b cc bn tin qung co tc nhn thng xuyn v nh k n tt c cc MS. Thay vo chng ch c pht n mt MS sau khi thit lp phin. Mt ci thin khc l PDSN ch lp li cc qung co theo mt s ln c lp cu hnh i vi mt MS. Ngoi ra PDSN dng pht i cc

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qung co n MS ngay sau khi n nhn c yu cu ng k t MS ny. Khi MIP hot ng trn kt ni PPP, thi hn hiu lc ng k MIP phi nh hn ng h thi gian khng tch cc PPP. MIP cung cp tp cc th tc an ninh gia client di ng (MS) v cc tc nhn di ng v gia cc tc nhn di ng. iu quan trng l phi c mt knh gia MS v HA cho cc bn tin ng k. Lin kt an ninh ny c th c thit lp bng cch trang b c nh (ti thi im ng k) cc kha gia MS v HA. MIP khng yu cu c ch nhn thc gia FA v HA. Tuy nhin trong mi trng kinh doanh nh cc mng thng tin di ng, cn nhn thc tt c cc bn tin gia FA v HA chng li s xm hi cc dch v v thit lp c ch tnh cc tin cy gia mng nh v mng khch. Tiu chun (TIA/EIA/IS-835) h tr cc ty chn sau y phn phi kha gia FA v HA: IKE v chng nhn cng cng (X.509) Kha b mt IKE quy nh chia s ng c phn phi bi AAA server nh Kha chia s IKE quy nh lp cu hnh tnh

Th tc an ninh MS-FA c m bo bi c ch h lnh/tr li c m t trong RFC 3012. PDSN khi u nhn thc ngi s dng trong min khch khi ng k ngi s dng. PDSN a phn m rng h lnh MS-FA trong qung co tc nhn. V cc qung co c pht khng thng xuyn, PDSN a h lnh tip theo vo tr li ng k. MS s dng h lnh tip theo ny trong ng k tip theo vi PDSN. PDSN truyn thng tin tr li h lnh FA nhn c t MS n AAA server nh thng qua AAA server khch. 1.8.5. Nhn thc cdma2000 MS s dng dch v thoi ch cn nhn thc mt ln trn giao din v tuyn.

MS yu cu dch v s liu trong cc h thng cdma2000 s b nhn thc hai ln: trn lp giao din v tuyn v nhn thc mng. Nhn thc giao din v tuyn c thc hin bi h tng HLR/AuC v VLR. Qu trnh ny da trn IMSI c nh ngha trong IS2000. Nhn thc trm di ng lp lin kt cdma2000 hay truy nhp mng truyn s liu gi, c thc hin bi cc c s h tng ca cc server AAA v cc client, trong cc client dc t trong cc PDSN v cc HA. Qu trnh ny da trn NAI (Network Access Identifier c nh ngha bi IETF trong [RFC2486]. y l s nhn dang c dng user@homedomain (ngi s dng@min nh) cho php mng khch nhn dng AAA server mng nh bng cch chuyn nhn "homedomain" thnh a ch AAA IP. H lnh t PDSN cng cho php bo v chng cc tn cng theo cch pht li. Ngoi ra, NAI cho php phn pht lin kt an ninh MIP c th h tr nhn thc PDSN/HA trong thi gian ng k di ng, n nh HA v chuyn giao gia cc

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PDSN. Lu rng AAA ca mng s liu nhn thc ngi s dng v khng nh nhn thc lp vt l ch nhn thc MS. V th ngi s dng mun truy nhp n cc mng s liu cng cng hay ring phi thc hin ng nhp v mt khu ging nh cc ngi s dng truy nhp s liu t xa, ngoi vic nhn thc thit b di ng xy ra trong giai on ng k, iu ny dn n tm dng khi khi u in thoi nh thng thy i vi hu ht cc ngi s dng my thoi di ng. H thng s liu cdma2000 m bo hai c ch nhn thc khi s dng cc phng php truy nhp IP n gin v MIP nh nh ngha trong [IS835] v [RFC3141]. i vi ch truy nhp IP n gin, nhn thc da trn CHAP, y l mt b phn ca m phn PPP. Trong CHAP, PDSN hi h lnh MS bng mt gi tr ngu nhin. MS phi tr li bng mt ch k da trn tm tt h lnh MD-5, mt tn ngi s dng v mt mt khu. PDSN chuyn cp h lnh/tr li n AAA server nh nhn thc ngi s dng. i vi MIP, PDSN gi i mt h lnh tng t cng trong bn tin qung co tc nhn. Tng t, MS phi tr li h lnh ny bng mt ch k v NAI (c kim tra bi mng nh), nhng ln ny tr li c gi i cng vi yu cu ng k ch khng phi trong khi thit lp phin PPP. C hai c ch ny u da trn cc b mt dng chung lin kt vi NAI c lu ti mng nh v c hai c h tr bi cng mt h tng AAA server. Trong c hai trng hp, s liu thanh ton c thu thp trong PDSN v c truyn n AAA server. PDSN thu thp thng k mc s dng s liu cho tng ngi s dng, kt hp chng vi cc bn ghi thanh ton truy nhp v tuyn do PCF gi n v gi chng n AAA server a phng. Lu rng thng tin thanh ton c thu thp bi c hai PCF v PDSN. i vi cc ngi s dng chuyn mng, AAA server c th c lp cu hnh chuyn mt bn sao ca tt c cc bn tin thanh ton RADIUS n AAA server nh ngoi vic gi bn sao ny ti AAA server khch. Trong qu trnh trao i cc bn tin bo hiu gia AAA nh v AAA khch, nu cn c th s dng thm AAA mi gii. 1.8.6. Cc phn t mi cho cdma20001xEV-DO Qualcomm xut tiu chun cdma20001xEV-DO ( Evolution for Data Optimized: pht trin cho s liu ti u) vo thng 3 nm 2000 h tr cc dch v sliu cao.. cdma1xEV-DO l mt h thng lai ghp CDMA/TDM v c hai li im khi h tr cc dch v tc s liu cao..Trc ht n c th h tr tc s liu ln n 2,4576 Mbps vi bng thng 1,25MHz, trong khi cdma20001x thun ty ch c th h tr tc s liu 2.0736 vi bng thng gp 3 ln (3,75 MHz). 1.8.6.1. Mng truy nhp, AN Bao gm cc thit b mng m bo kt ni s liu gia mng chuyn mch s liu (thng l internet) v thit bi u cui (AT). Mng truy nhp tng ng vi BTS trong cdma 2000

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1.8.6.2. Thit b truy nhp (AT) Thit b truy nhp (AT) m bo kt ni ca ngi s dng. AT c th c ni n n thit b tnh nh my tn xch tay hay c th l thit b c cha my tnh nh PDA. AT tng ng vi MS trong cdma2000 1.8.6.3. AAA cu mng truy nhp (AN AAA) L phn t thc hin cc chc nng nhn thc v trao quyn cho mng truy nhp 1.8.6.4. Kt ni Kt ni l mt trng thi ca ng v tuyn trong AT c n nh mt knh lu lng ng xung, mt knh lu lng ng ln v cc knh MAC i km. Trong mt phin HRPD (High Rate Packet Data) AT v AN c th m v ng kt ni nhiu ln. 1.8.6.5. MS/AT lai ghp MS/AT lai ghp l mt thit b c kh nng lm vic c mng cdma2000 v cc mng HRPD AN. 1.8.6.6. Lung dch v Lung HRPD (High Rate Packet Data: s liu gi tc cao) c s dng trao i s liu gia cdma2000 v PDSN. 1.8.6.7. Phin HRPD Phin HRPD (1xEVDO) c coi l mt trng thi chung gia AT v AN. Trng thi ny lu gi cc giao thc v cc cu hnh giao thc c m phn v c s dng thng tin gia AT v AN. Nu khng m phin AT khng th thng tin vi AN khi AN khng m phin. 1.8.6.8. PCF PCF c thm thm chc nng nng SC/MM v m bo hot ng c th HRPD. 1.8.6.9. Phin s liu gi L trng hp s dng dch v s liu gi ca ngi s dng. Phin s liu gi c bt u khi ngi s dng yu cu dch v s liu gi v kt thc khi ngi s dng hoc mng kt thc dch v s liu gi. Trong thi gian phin, ngi s dng c th thay i v tr nhng vn duy tr a ch IP khng i. 1.8.6.10. Chc nng SC/MM

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SC/MM (Session Control and Mobility Management: iu khin phin v qun l di ng) c t ti PDF v bao gm cc chc nng sau:

Lu gi cc thng tin lin quan n phin HRPD: duy tr ng h thi gian tn ti, MNID, chuyn i gia MNID v UATI cho mt AT) i vi cc AT ng

n nh UATI (Unicast AT Identifier: nhn dng AT n phng) cho AT Nhn thc u cui. Chc nng ny thc hin th tc nhn thc u cui. N

quyt nh AT c phi nhn thc hay khng khi AT truy nhp HRDP RAN. Qun l di ng. Chc nng ny qun l v tr ca AT. Thng tin v v tr

ca AT nhn c thng qua ng k da trn khong cch. Chc nng ny c th thc hin th tc tm gi da trn thng tin trn.

1.8.6.11. Nhn thc u cui L th tc trong AT c nhn thc bi AN-AAA. Mng thng tin di ng ang tin ti mt mng ton IP, trong cc phn di y ta s xt cc .mt s vn quan trng lin quan n kt ni mng thng tin di ng trn c s IP. 1.9. NH A CH IP 1.9.1. nh a ch IP trong IPv4

Kch thc ca a ch IPv4 l 32 bit (4 byte). Khng gian a ch c chia thnh hai phn, mt phn nhn dng mng v mt phn nhn dng my trong mng. Trong khi a ch thc t th hin my tnh l 32 bit nh phn, th a ch IP c vit dng sau:. 32 bit a ch c chia thnh bn on tm bit phn cch vi nhau bi du chm, trong mi on c th hin bng mt s thp phn nm trong di t 0 n 255, th d:

152.226.86.23 V c 4 byte, nn di a ch tri rng t 0.0.0.0 n 255.255.255.255 vi ti

tng s a ch ln n hn 4 t. Tuy nhin do cch cp pht a ch trong thc t, khng gian da ch nh hn khng gian ni trn. C bn loi a ch nh cho trong bng 1.1. Mi lai cho php nh a ch cho mt s lng mng v s lng my nht nh. a ch loi A c 8 bit nhn dng mng v 24 bit nhn dng my. Bit u tin ca loi A lun bng khng router nhn dng loi A. Cc a ch loi B s dng 16 bit cho nhn dng mng v 16 bit cho nhn dng my. Bit u tin cu n lun lun bng 10 router nhn ra loi a ch ny. a ch loi C c 24 bit dnh cho a ch mng v 8 bit dnh cho a ch my, bit u ca n lun lun bng 110 router c th nhn dng c a ch ny. a ch loi D dnh cho pht a phng, a ch ny gm 8 bit u l a ch mng v 24 bit cn li l a ch cho nhm a phng, ba bit u tin cu i ch ny l 110. Cc a ch lai E d phng v cha c chun

27


ha. Cc a ch loi A bt u bng 1-126, cc a ch loi B bt u bng 128-191, cc a ch loi C bt u bng 192-223 v cc a ch loi D (truyn a phng) bt u bng 224-239. Cc a ch loi E bt u t 240-247. Chng hn, 152.266.0.0 l a ch loi B v v th n h tr cc a ch trong di t 152.266.0.0 n 152.226.255.255.

Mt n a ch mng c s dng nh mt b lc ly ra a ch mng. Chng hn s dng mt n cho trong bng 2.2 ta c th tnh ra a ch mng cho mt a ch loi B: 152.226.86.23 bng cch nhn logic tng bit a ch IP vi mt n. Trong trng hp ny v a ch IP l loi B nn mt n cu n l 255.255.0.0. Kt qu nhn cho ta a ch mng: 152.226.0.0. y l a ch m router cn nh tuyn.

Trong khng gian a ch my c hai a ch c s dng cho vic khc (mt n v qung b) v th tng s a ch dnh cho my s c tnh nh sau:

2(s bit a ch my)-2 Chng hn i vi a ch loi C, khng gian dnh cho a ch my l 8 bit nn s a ch my c th c s l: 28-2=254 a ch Bng 1.1. Cc khun dng a ch IPv4 Loi ngha Kch th-

c trng a ch mng

Kch thc trng a

ch my

Tng s a ch mng

Tng s a ch

my

Phn u tin ca cc bit a ch IP/di a

ch

Mt n mc nh

mng

A 1 byte nhn dng mng, 3 byte nhn dng my

7 24 126 16.777.2144

0/1.0.0.0-126.255.255.255

255.0.0.0

B 2 byte nhn dng mng, 2 byte nhn dng my

14 16 16384 65.534 10/128.0.0.0-191.255.255.255

255.255.0.0

C 3 byte nhn dng mng, 1 byte nhn dng my

21 8 2097152 254 110/192.0.0.0-223.255.255.255

255.255.255.0

D a ch a phng

4 bit 24 (nhm qung b)

1110/224 .0.0.0-239.255.255.255

28


E D tr cho tng lai

11110/240.0.0.0-247.255.255.255

a ch hi tip-my a phng

127.x.x.x

Mt mng thng c chia thnh cc mng con c s my t hn. chia mng con ta c th s dng mt phn 32 bit a ch ch th mng con v phn cn li ch a ch cu my trong mng con. Chng hn s dng loi C ta c th c 6 mng con mi mng c 30 my. Hnh 1.8 cho thy cch tng s mng con ng thi vi gim s my trong mi mng con. Bng 1.2 cho thy ta c th tng s s 1 trong mt n to ra mt mng con (th d c xt cho loi B). Bng 1.2. Tng s mng con bng cch tng s s 1 trong mt n Mt n mng con Dng bit Cc mng con Cc trm 255.255.0.0 255.255.192.0 255.255.224.0 255.255.240.0 255.255.248.0 255.255.252.0 255.255.254.0 255.255.255.0

11111111.11111111.00000000. 00000000 11111111.11111111.11000000. 00000000 11111111.11111111.11100000. 00000000 11111111.11111111.11110000. 00000000 11111111.11111111.11111000. 00000000 11111111.11111111.11111100. 00000000 11111111.11111111.11111110. 00000000 11111111.11111111.11111111. 00000000

0 2 6 14 30 62 126 254

65534 16382 8190 4094 2046 1022 510 254

Phng php s dng cc mt n mng con khc nhau nhn dng cc mang

con c gi l to mt n mng c di kh bin (VLSNM: Variable Length Subnet Masking). Hnh 2.10 cho thy phng php ny.

Hnh 1.8. iu chnh s bit 1 trong mt n iu chnh s mng con con v s my trong mi mng con.

V loi A ch c 126 a ch mng, nn cc a ch mng ny lc u c c cp pht cho cc t chc c cc mng ni b rt ln. Loi B dnh 14 bit nh a ch mng, v th n m bo nhiu mng hn vi khng gian a ch my nh hn (ch c 65 534 my trn mt mng). Loi C c khng gian a ch my nh nht: 254 a ch my, nhng li c s a ch mng ln nht. V nhiu t chc c nhiu hn 254 my nn nhu cu lai B rt cao. iu ny dn n thiu ht i ch. v th cn phi tm

29


ra phng cch n nh a ch ph hp cho cc t chc c kch c trung bnh (s my ln hn 254). Cc vn ny v cc vn khc na s c gii quyt bng cch s dng NAT (s xt phn sau) hoc trit hn bng cch s dng IPv6. IPv6 s dng 128 bit a ch v v th m bo ngun a ch rt ln.

Cn lu rng, c mt s a ch c bit khng c dng. Cng thc chung dng tnh ton s a ch mng con v s my khi bit mt n mng con nh sau:

S mng con c th c= 2(s bit mt n)-2 S my c th c = 2(s bit khng thuc mt n)-2

lm th d ta xt mng loi B s dng mt n mng con 255.255.240.0. Mt n loi B trong trng hp ny c thm bn bit 1 (th hin bng 240) to nn mt n mng con, v th S mng con = 24-2 = 14 S my trong mi mng con = 212-2 = 4029 Trong th d trn a ch mng lai B c m rng thm 4 bt t mt a ch loi B c cp pht cho mng t chc khai thc c th to ra t a ch ny 4029 a ch mng con khc nhau. m rng mt a ch mng B thm 10 bit to ra cc a mng con, ta s dng mt n sau: 255.255.255.192 . Trong trng hp ny ta c: S mng con = 210-2= 1022 S my trong mi mng con = 26-2=62 Trong trng hp ny nu ta nh a ch IP cho mt my bng 172.16.2.160 c byte dng nh phn l:1010000, th a ch mng con tng ng ca n s l: 172.16.2.128. Bng 1.3 lit k cc a ch c ngha c bit trong giao thc IP v khng c s dng n nh a ch. Bng 1.3. Cc i ch c ngha c bit

a ch Hm 0.0.0.0 127.0.0.0 a ch c a ch mng ton cc bit khng

ni rng y l mng mc nh Dnh cho u vng. Thng thng 127.0.0.1 c s dng cho mc ch th nghim ni rng y chnh l mng, chng hn 135.34.0.0 ni rng mng l 135.34. a ch ny c s dng trong cc bn nh tuyn

30


a ch mng hay a ch my c ton cc bit 1 255.255.255.255

ni v tt c cc my" a ch qung b

Ngoi ra IETF nh ngha cc a ch ch dnh s dng lm a ch ring ni b trong cc mng ring ch khng c s dng trong internet (cho bng 1.4) Bng 1.4. Cc a ch ring c th s dng li Loi A 10.0.0.0 Loi B 172.16.0.0-172.31.0.0 Loi C 192.168.0.0-192.168.255.0 V cc a ch IPv4 ch c 32 bit, nn khng gian a ch l thuyt ch cho php nh a ch cho 4 294 967 296 my. Cu trc phn lai ni trn gim khng gian ny xung cn 3,7 t. Ngoi ra khng gian ny b gim tip do lng ph khng gian a ch khng s dng trong khng gian loi B. i vi a phn cc t chc, khng gian loi A vi 16 triu a ch qu ln, trong khi khng gian loi C vi i ch 254 li qu nh. V th hu ht cc t chc mong mun c c khng gian loi B . iu ny c ngha rng mt t chc ch c 2000 my s dng khng gian loi B vi 65 534 a ch, khng gian ny vn qu ln so vi yu cu. Trong trng hp ny 97% khng gian a ch c cp pht b lng ph. Mt vn khc ny sinh l ch c 16 383 a ch mng kh dng cho loi B. V th nu mi t chc u yu cu mt a ch mng khng gian loi B th cc a ch ny s nhanh chng ht. gii quyt vn ny ta c th n nh tm a ch khng gian loi C cho t chc c 2000 my ny. Gii php ny c th gii quyt c vn cp pht a ch nhng li lm cho cc bng nh tuyn qu ln. Khi ny thay v ch cn mt mc trong bng nh tuyn cho khng gian a ch loi B, t chc ny cn phi c tm mc trong bng nh tuyn cho tm a ch mng khng gian loi C. 1.9.2. Mt s gii php thiu ht a ch cho thng tin di dng Cng vi s ra i ca cc h thng thng tin di ng th h sau cng s pht trin mnh cc ng dng IP trong thng tin di ng v thc t l s thu bao di ng ton cu ln n trn mt t to ra mt p lc mi i vi khng gian a ch c hn ca IPv4. Hin nay mt s lng ln cc a ch IP c cp pht cho cc nh cung cp dch v internet chnh (ISP) v ch cn li khng gian a ch khng ln dnh cho tng lai. Tt nhin khi a ra s dng IPv6 vn ny s c gii quyt trit , tuy nhin cho n khi ta cn tm ra gii php khc phc thiu ht a ch cho IPv4. Hin nay hai gii php c s dng cho cc t chc thc hin kt ni cho cc ngi s dng mng intranet l: giao thc lp cu hnh my t ng (DHCP: Dynamic Host

31


Configuration Protocol) v bin dch a ch mng (NAT: Network Address Translator). 1. Giao thc lp cu hnh my t ng (DHCP) S dng DHCP tit kim khng gian a ch da trn trit l l khng phi tt c cc UE u s dng cc dch v IP ti mt thi im cho trc. ISP hay nh khai thc khi u vi mt t hp cc a ch. Khi mt ngi s dng yu cu kt ni n dch v IP, ngi ny s c cp pht tm thi mt a ch IP t t hp. Qu trnh ny c gi l thu mt a ch. Phng php ny cng rt ging nh cch thc m PABX h tr nhiu ngi s dng bng mt s trung k ngoi hu hn. Giao thc h tr lp cu hnh my ng c gi l DHCP, n c cc ISP s dng ton cu n nh cc a ch IP cho cc ngi s dng cu h. DHCP cng n nh cc a ch quan trng khc cho my nh DNS server mc nh v cng mc nh. DHCP c s dng trong cc h thng 3G cp pht ng mt a ch IP cho thit b di ng khi thit b ny yu cu tch cc PDP context. N c s dng cho cc UE khi cc UE ny khng c chuyn i tnh trong HLR i vi mt im truy nhp nht nh. Nu ngi s dng ni n mt mng ngoi, th n nh DHCP c thc hin trong ng trc GPRS IP. Thng thng DHCP c t bn trong GGSN. Phng php n nh ny c gi l ch trong sut. Tuy nhin nu ngi s dng ni n mng intranet hng, th a ch IP c th c n nh bn trong mng ny. Phng php ny c gi l ch khng trong sut. 2. Bin dch a ch mng (NAT) DHCP ch hot ng tt khi n nh mt t hp hu hn cc a ch cho mt s ngi s dng nhng khng th m rng ton b khng gian a ch kh dng. n nh a ch PDP cho UE, a ch IP cng cng ca IPv4 l khng , v th ngi ta phi s dng a ch ring. s dng a ch ring cn c NAT phin dch a ch cng cng vo a ch ring. NAT cho php mt mng ni b intranet c th s dng cc i ch ring vi khng gian a ch ln m khng s chng ln cc a ch ny ln cc a ch IP nh tuyn ton cu. C th coi NAT l mt router ni gia hai mng: mng ni b intranet v mng ngoi internet. i vi mng internet NAT pht i a ch IP nh tuyn ton cu cn i vi mng ni b intranet NAT pht i a ch ring. V th bn trong mt mng di ng, nh qun l c th nh a ch ring cho cc trm di ng (MS: Mobile Station) khc nhau. Nhiu a ch ring cu cc MS c th c sp xp ln mt hay nhiu a ch ton cu khi pht ra mng internet. phn bit cc MS, s ca c s dng. Nh vy trn mng internet mi MS c nhn dng bi hai s nhn dng: a ch internet ton cu (chung vi nhiu MS khc) v s ca (ring cho mi internet). Mt gi t mt MS trc khi a ra mng internet ngoi c NAT

32


phin dch a ch ring cu MS vo mt a ch IP nh tuyn ton cu v mt s ca. Ngc li mt gi c gi t mng internet ngoi vo cho MS c NAT phin dch vo a ch ring da trn a ch nh tuyn ton cu v s ca. Chc nng NAT cng thng c kt hp trong tng la m nh qun l mng s dng bo v an ninh mng. Thng thng mt nh khai thc hot ng vi a ch mng loi C ch c th h tr 254 a ch IP. Mng UMTS cn phc v mt s lng ln UE ni n internet m khng cn s lng ln cc a ch IP cng cng. Di a ch c dnh ring cho vic s dng ni b c cho trong bng 1.5. Bng 1.5. Cc a ch ring c th ti s dng

Loi Cc a ch A B C

10.0.0.0 172.16.0-172.31.0.0 192.168.0.0-192.168.255,0

Cc a ch trong bng 1.5 c th c chn s dng ni b trong mng

ring cu mt nh khai thc. gii quyt vn thiu ht a ch, nh khai thc phi n nh cc a ch IP

ni b ring cho UE khi tch cc PDP context (thng iu ny c thc hin bi DHCP). Khi ngi s dng ni n Internet, NAT thc hin chuyn i a ch ring ny thnh a ch cng cng c th nh tuyn c trong mng Internet. Dng NAT n gin nht l phin dch c nh: tn ti quy nh chuyn i c nh gia a ch IP ring v a ch IP cng cng. Dng ny thng c s dng cho cc server truy nhp cng cng (cng WAP chng hn). Cc server ny c t c nh, tip nhn cc kt ni n n v chuyn i a ch ni b thnh a ch ngoi. Tuy nhin dng ny khng ph hp vi cc UE v cc UE ny ch c n nh a ch khi n cn kt ni n internet. Trong trng hp ny ngi ta s dng phin dch ng, trong cc UE chia s chung mt a ch ngoi (a ch IP cng cng) bng cch s dng a ch ring. Trong trng hp ny m bo phin dch a ch ng, cc a ch IP ni b khc nhau c chuyn i vo cc s ca khc nhau trong router. NAT ny thng c t bn trong GGSN, nhng n cng c th c t ring hay c th kt hp vi tng la. Phin dch ng i khi c gi l NAPT (Network Address and Port Translation), nhng cch gi ph bin hn vn l NAT. Cc gi TCP hay UDP c gi tr ca 16 bit cho php to ra 216=65 536 ca trn mt i ch IP. Cc ca thp hn 1024 c gi l cc ca bit r v c s dng cho cc dch v c th. Cc ca cao hn di ny c s dng cho NAT. Ta xt th d trn hnh 1.9. Nh khai thc s dng a ch ring loi A 10.0.0.0 lm a ch ni b v c a ch cng cng loi C l 212.56.65.0 v UE c n nh a ch IP 10.1.1.102 bi DHCP. Ngi s dng ni n web server ngoi c a ch 135.237.78.6:80, trong 80 nhn dng

33


dch v HTTP. UE gi i yu cu truy nhp HTTP trn web server theo a ch c cp pht l 10.1.1.102:1345, trong 1345 l s ca. Ti NAT, a ch trong cu yu cu c dch thnh a ch ngoi loi C 212.56.65.10 vi s ca 16456. Web server s tr li theo a ch loi C ny v NAT phin dch n vo a ch trong 10.1.1.102:1345.

Mi khi mt kt ni TCP c thit lp, mc chuyn i ca c to ra trong bng tra cu v khi kt thc kt ni TCP mc ny s b xa. Cn c mt dng NAT na l phin dch cn bng ti, trong mt router co th m rng cc kt ni ca mt server qu bn n mt s server cng chc nng khc v mi server ny c a ch duy nht. Trng hp ny thng xy ra khi truy nhp n mt web server bn trn internet. Router s kim tra xem server no t bn nht v t phin dch IP cho server ny. Cn lu rng cn bng ti thng c xy dng theo phng php ring v cc server cn thng tin v mc kh dng ca chng cho router trong khun dng m router hiu c.

Mt mng s dng NAT c th m bo nh a ch cho trn 16 triu UE. Hn ch ln nht ca dch v NAT l cng sut x l nht l khi dch v ny c t trong thit b phi thc hin cc dch v khc chng hn GGSN ny tng la. Ngoi ra s dng NAT cho UDP cng dn n vn cn x l. V UDP khng theo ni thng, NAT khng c mt thng tin no v phin thng bo cho n xa mc phin dch. Trong trng hp UDP, ngi ta phi s dng c ch tm ngng xc nh khi no kt thc v loi b phin dch.

Hnh 1.9. M t hot ng ca NAT 1.9.3. nh a ch IP trong IPv6 Trng a ch ngun v nhn trong trong IPv6 l mt trng 128 bit nhn dng ngun pht gi v nhn dng ni thu gi.

34


a ch IPv4 thng c biu din bi cc s thp phn c phn cch bng du chm. 32 bit a ch c chia thnh bn on tm bit phn cch vi nhau bi du chm, trong mi on c th hin bng mt s thp phn nm trong di t 0 n 255, chng hn: 152.226.51.126. Cch trnh by ny khng thch hp cho IPv6 v cc a ch IP ca n di 128 bit, nn IPv6 s dng cch trnh by a ch khc (RFC 2373). Phng php trnh by thch hp nht l: x:x:x:x:x:x:x:x Trong x l mt on 16 bit c th hin c s 16. Th d a ch IPv6 c dng sau: DEFC:A9BE:1236:DE89:D7FE:4535:908A:4DEF Ta thy rng cc on 16 bit c phn cch nhau bi du hai chm v mi on c th hin bng bn ch s c s 16. Nu c cc on cha cc s u bng khng th cc s khng ny c th b qua, th d: DEC5:0000:0000:0000:0009:0600:3EDC:AB41 c th trnh by n gin l: DEC5:0:0:0:9:600:3EDC:AB41 Nu c nhiu on lin tip ch cha ton khng th c th biu din n gin cc on bng bng du hai chm kp ::, th d: DEC5::9:600:3EDC:AB41 Ch c s dng du hai chm kp mt ln trong mt a ch mc d c th xut hin cc xu khng trc v sau trong a ch. Th d a ch sau: 0:0:0:0:0:0:0:1 C th vit n gin l: ::1 Khng gain a ch ca IPv6 cho php gii quyt vn thiu ht a ch trong IPv4. Tuy nhin do hin nay trn th gii cn c qu nhiu IPv4 router nn vic thay th IPv4 bng IPv6 i hi thi gian. Trong giai on qu ny cn c cc gii php chuyn i gia IPv4 v IPv6. Mt s gii php chuyn i c s dng nh: lp IP kp (trong mt trm h tr c IPv4 ln IPv6), truyn tunnel (trong gi IPv4 khi truyn trong min IPv6 c ng bao vo tiu IPv6 v ngc li) 1.9.4. H thng tn min (DNS) DNS (Domain Name System) chuyn i cc tn dng vn bn vo cc a ch IP v ngc li. N trnh cho ngi s dng khng phi nh a ch IP khi truy nhp n mt dch v nht nh bng cch cung cp tra cu chuyn i gia tn vn bn v a ch IP. Phng php ny ging nh phng php trong thng tin di ng, trong cc ngi s dng c th tm n i tc ca h theo tn cu cc i tc ny cn s tay thoi lu trong thit b s m bo vic chuyn i tn ny vo s my di ng ca i tc. Chng hn s dng DNS, tn website ca mt hng c th c tm theo tn nm gia www v com. Ngi s dng ch vic nh www.tn hng.com

35


vo b trnh duyt. Sau a ch ny c a n DNS server v server ny c nhim v chuyn n vo a ch IP. Cc tn min c t chc v qun l theo hnh cy phn cp. Hnh 1.10 cho thy mt tp nh ca khng gian t tn DNS. Khng gian tn i vi DNS c chia nh v c qun l theo hnh cy. y l tn min. Qu trnh dch t pha phi tn min sang pha tri tn min tng ng vi dch t pha trn cu cy xung cc nhnh di. Th d trn hnh 1.9 ta thy tn min cam.ac.uk. y l min ca trng i hc Cambrridge v v th chu s qun tr ca h thng qun tr mng ca trng i hc Cambridge. Min ny nm bn trong ac.uk, ac.uk l min c n nh cho tt c cc c s i hc trong nc Anh. n lt mnh ac.uk li nm trong min uk, min uk l min dnh cho tt c cc tn min trong nc Anh. Vic phn on khng gian a ch cho php mt nh khai thc c th n nh cc tn DNS mi m khng s gy ra chng ln cc tn ny (hai t chc c cng mt tn web server), v khng gian tn cu h c phn bit bi phn cui ca cc a ch DNS. Chng hn trng i hc Cambrridge c th tin chc rng a ch ca h lun khc vi a ch ca trng i hc Oxford.

com

3com

my sg th uk

ox cam

ac

Gc

Hnh 1.10. Phn cp khng gian tn min ca DNS Khi chuyn tn DNS vo a ch IP, client phi tham kho DNS server. Hu ht cc client u c a ch DNS server mc nh c n nh theo cu hnh. Nu DNS server i phng khng c quy nh chuyn i cho a ch DNS, n s s dng tn DNS tm ra ni tra cu quy nh chuyn i ny. Chng hn khi cn chuyn i a ch DNS www.3com.com, trc ht DNS server a phng phi hi server gc DNS ca internet v a ch ca server c tn .com x l min .com. Sau khi nhn c a ch ny, client hi server tn .com v a ch v a ch cu server c tn .3com. Sau khi tm c server c tn .3com, client hi n v a ch www.3com.com. Qu trnh ny c thc hin t gc cy cho tt c cc tn v thc hin qu trnh ny c th l

36


client hoc l mt server khc i din cho n. Khi mt server tn ngoi thc hin tt c cc cng vic ny a din cho client, qu trnh ny c gi l tra cu DNS quy. Tra cu DNS quy c li cho client bi v client khng phi thc hin qu nhiu vic v gim lu lng ni vng a phng. iu ny c bit quan trng i vi cc client s dng ng truyn v tuyn. Lu rng mi server tn u bit a ch ca server con (server pha di) nhng khng nht thit phi bit a ch ca server con ca con ca n. Ngoi ra server tn phi bit a ch ca ca server m cu mnh (server pha trn) n c th gi cc yu cu cha hiu n cp bc DNS cao hn. Trong GPRS, DNS c s dng phn gii tn im truy nhp (APN: Access Point Name). APN xc nh giao din ca GGSN vi mng ngoi m ngi s dng s ni n. Qu trnh tch cc ng cnh giao thc gi s liu (PDP context) s thng bo cho mng v APN yu cu v APN ny c chuyn i vo a ch IP ca GGSN. 1.9.5. Giao thc phn gii a ch (ARP) Giao thc ARP (Address Resolution Protocol) chu trch nhim chuyn i cc a ch IP thnh cc a ch MAC (Media Access Control: iu khin truy nhp phng tin). Chuyn i ny rt quan trng trong IP v thc t cc khung c nh tuyn n ni nhn trong mng LAN ch s dng a ch MAC thay v a ch IP. a ch MAC l mt a ch bao gm 48 bit (6 byte) ci trong phn cng ca giao din mng, v th hai card giao din khng th c chung mt a ch. Ba byte u ca a ch ny ch th nh sn xut v ba byte cn li do nh sn xut quy inh khi sn xut ra card mi. Chng hn, khi gi i mt gi trn mng ethernet, ta phi bit c c a ch MAC ln a ch IP ca ni nhn. Hot ng ca giao thc ny nh sau. Mt gi yu cu ARP c pht trn LAN trong a ch MAC c t vo qung b (Broadcast). Bn tin qung b cng cha c a ch IP ra mng ngoi cn thit cho chuyn i. a ch qung b MAC bao gm a ch ni nhn c t tt c l 1 (FFFFFFFFFFFF). Tt c cc trm trong LAN s nhn v phn tch khung ny nhng ch mt trm nhn ra a ch IP cu n trong yu cu v trm ny gi i tr li n pha pht. Trong tr li, pha thu t vo a ch MAC ca chnh mnh. Khi c bn sao a ch cng (a ch MAC), pha pht c th gi cc gi trc tip n a ch IP ny. Thc t, ARP hot ng cng vi b nh a phng lu cc bn sao chuyn i ARP mi nhn. B nh ny cho php gim lu lng mng v tng hiu nng. Hnh 1.11 cho thy mt Ethernet ni n Internet. Nu mt trm c a ch IP l 192.10.1.100 cn gi mt gi n a ch 192.10.1.1, gi s c gi nh ch dn trong bng 1.6. Nu trm 192.10.1.100 cn gi mt gi n a ch 166.10.10.1, a ch ny khng nm cng mng con. Gi ny phi gi qua router ti 192.10.1.254, v th yu

37


cu ARP s dnh cho a ch Ethernet cu router. Cc bn tin c cho trong bng 1.7. Khi ny trm s gi gi n Ethernet theo a ch 00800123ABDF. Lu rng khi my c a ch 192.10.1.100 gi gi n ni nhn, mc d n gi gi theo a ch Ethernet cu router, a ch IP s c t vo 166.10.10.1 (a ch nhn cui cng) ch khng phi a ch IP ca router.

Hnh 1.11. M t th d v ARP v a ch MAC: (1) ni gi hai trm bn trong ethernet, (2) ni vi mt trm ngoi ethernet Bng 1.6. Th d ARP (1) Kiu gi a ch IP

nhn i ch MAC

nhn a ch IP

ngun a ch MAC

ngun Yu cu ARP Tr li ARP

192.10.1.101 192.10.1.100

FFFFFFFFFFFF008001234567

192.10.1.100 192.10.1.101

008001234567 00AF01234567

Bng 1.7. Th d ARP (2) Kiu gi a ch IP

nhn i ch MAC

nhn a ch IP

ngun a ch MAC

ngun Yu cu ARP Tr li ARP

192.10.1.254 192.10.1.100

FFFFFFFFFFFF008001234567

192.10.1.100 192.10.1.254

008001234567 008001234ABD

1.10. TRUYN TUNNEL IP TRONG IP IP in IP cn c k hiu l IPIP, l dch v tunnel ph bin nht. N ng bao cc gi IP v mt gi IP khc. Phng php ng bao ny c c t trong [RFC2003] c pht trin cng vi [RFC2002] (tiu chun MIPv4 u tin). Trong IPIP, tiu ngoi ca gi IP nhn dng cc a ch ca cc im cui tunnel, trong

38


a ch ngun l i ch ca ni ng bao cn a ch nhn l a ch cu ni tho bao (xem hnh 1.12).

Hnh 1.12. ng bao v tho bao cho gi IP trng qu trn truyn tunnel V i khi vic ng bao mt gi IP vo mt gi IP khc dn n chi ph qu ln, nht l khi ti tin ca cc gi IP cn truyn tunnel qu nh, nn cn nh ngha thm cch nn thng tin lin quan n tiu cu gi IP bn trong. C hai giao thc IP in IP v ng bao ti thiu cho IP tunneling u da trn cc giao thc khc (chng hn MIP) hay cung cp phn t mng thit lp tunnel. IP in IP t mnh khng an ton v i hi IPsec cho chc nng ny. T hp c hai chc nng trn c gi l ch tunnel IPsec. Giao thc truyn tunnel GPRS (GTP) Trong GPRS v UMTS truyn cc gi trn IP ngi ta s dng giao thc truen tunnel GTP (GPRS Tunneling Protcol). GTP c s dng cho cc th tc bo hiu trong mt phng iu khin (GTP-c) v truyn s liu trong mt phng ngi s dng(GTP-u) gia cc GSN. N cung cp mt tiu v tiu ny cng vi tiu TCP/UDP v IP cho php nhn dng nt h tr GPRS (GSN: GPRS Support Node) nhn v x l gi ti ni nhn. Cn c mt GTP khc c gi l GTP' s dng cho giao thc tnh cc. GTP' c s dng gia cc GSN v CGF. Trong mt phng bo hiu, GTP-c l mt giao thc qun l v iu khin tunnel c s dng to lp, thay i v xo cc tunnel gia cc GSN. Cc th tc bo hiu ny bao gm: yu cu PDP context, cp nht PDP Context v xo PDP Context. Cc th tc ny c s dng nh l mt b phn cu thit lp phin hay qun l di ng gia SGSN v MS. Trong mt phng ngi s dng, GTP-u cung cp mt tiu truyn tunnel. Ngoi truyn tunnel, GTP-u cung cp cc tnh nng nh: truyn theo th t v ghp cc lung. 1.11. IP DI NG (MIP) 1.11.1. Nguyn l MIP

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MIP (Mobile Internet Protocol) cho php gi quyt vn ngi s dng trong mng di ng di chuyn ra khi mng nh ni ngi ny ng k a ch IP. V nhiu ngi s dng internet di chuyn t ni ny n ni khc, cn m bo truy nhp cc ti nguyn mng v cc dch v thun tin cho h khi di chuyn. L tng, mt ngi s dng c th ni n mt im truy nhp bt k ti ni m ngi ny n hay s dng mt kt ni di ng mt cch trong sut n mng nh ca mnh qua internet. Tr ngi y l vic nh a ch. Ta bit rng a ch ca internet bao gm 4 byte, chng hn 152.226.23.45. Trong th d ny 152.226 nhn dng mng nh ca ngi s dng; tt c cc gi c gi theo a ch ny c cc router hng n mng ny. Nu ngi s dng ang trc thuc mng ny th s khng c vn g. Tuy nhin nu ngi s dng di chuyn n mt mng khc, chng hn 145.67, th cc gi s khng bao gi n c ngi ny. S dng DHCP (Dynamic Host Configuration Protocol: giao thc lp cu hnh my ng), mt ngi s dng khi ng nhp vo mt mng mi c th nhn c mt a ch IP mi nhng cng khng gii quyt c vn ny, v a ch ny ch cho php truy nhp n mng khch m khng cho php truy nhp n mng nh (v thc t i tc ch bit a ch mng nh ca anh ta). Vy trong thc t vn ny c gii quyt MIP nh th no?. Hnh 1.13 cho thy cch gii quyt ca MIP. Mng nh phi c mt tc nhn nh (HA: Home Agent) v mng khch phi c mt tc nhn ngoi (FA: Foreign Agent). Khi my tnh ng nhp n mng khch, n s tip xc vi FA bng cch pht i bn tin khn ni yu cu qung co t pha FA (hay i cho n khi FA t pht i qung co). Trong qung co ca mnh, FA s cung cp mt danh sch cc chm sc a ch (CoA: Care of Address), cc CoA ny s c nt di ng s dng khi n nm trong mng ngoi.

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Router

165.5.5.2 128.4.5.6 165.5.5.2128.4.5.6

Ngunch Ngunch

Node i tc7 4

Router

Mng khch192.4.5.0

Internet

Mng nh128.4.0.0

Tc nhn ngoi

Tc nhn nhNode di ng

128.4.5.6

192.4.5.6

165.5.2.2

128.4.255.254

Gi tin IP Gi tin IP

Qung coCoA= 192.4.5.6

Yu cu ng kCoA= 192.4.5.6

a ch nh= 128.4.5.6Tc nhn nh= 128.4.255.254

S liu nhn thc

Yu cu ng kCoA= 192.4.5.6

a ch nh= 128.4.5.6Tc nhn nh= 128.4.255.254

S liu nhn thc

Gi tin IP

128.4.255.254 128.4.5.6 165.5.2.2192.4.5.6

ch chNgun NgunTiu ng hm Tiu trong

Gi tin IP

128.4.5.6 165.5.2.2

ch Ngun

1

2

3

5

6

Hnh 1.13. Hot ng ca MIP. 1.11.2. nh tuyn MIP Trong MIP, mi ngi s dng khi di chuyn vo mng khch s ng k CoA vi HA ca mnh. Lin kt gia CoA vi ngi s dng c gi l rng buc (binding) a ch nh ngi s dng. Khi cc gi c gi n my ca ngi s dng, HA s nhn chng, sau chuyn chng n FA theo CoA. Mi gi sau c ng bao vo mt tiu IP ngoi v c truyn tunnel t HA n FA. Bng cch ny gi gc khng b thay i v qu trnh di ng tr nn trong sut i vi cc my u cui. Khi FA nhn c gi ti u cui tunnel, n loi b tiu ngoi v chuyn ni dung thng n ngi s dng. Ti phng ngc li, cc gi c th c gi thng n my i tc v khng cn phi truyn qua mng nh ca ngi s dng. Hnh 1.13 m t chi tit cc bc ni trn trong MIP nh sau:

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1. Khi di chuyn vo mng khch, my di ng nhn c qung co cha a ch CoA 192.4.5.6

2. My di ng pht yu cu ng k CoA, a ch HA (128.4.255.254), a ch nh ca my (128.4.5.6) v s liu nhn thc n FA. Bn tin ny cha c thi hn hiu lc ca rng buc (khng ch ra trn hnh v)

3. FA chuyn yu cu ng k n HA. Sau HA s dng thng tin ny to lp rng buc gia a ch nh ca nt di ng (128.4.5.6) v CoA (192.4.5.6)

4. Gi c gi t nt i tc n nt di ng theo a ch nh ca nt ny (128.4.5.6) v c HA thu nhn

5. HA truyn tunnel gi ny n FA theo CoA ng k 6. FA nhn gi, loi b tiu ngoi ri chuyn n n nt di ng theo a ch

192.4.5.6) 7. My di ng gi gi tr li trc tip n my i tc. V cc yu cu ng k MIP c s dng thay i nh tuyn cc gi di ng, nn cc ng k la o (t cc ngi s dng khng c php) c th c s dng dn n tn cng t chi dch v (DoS) trn mng. V th cc bn tin ng k MIP u cha mt trng nhn thc. Trng ny c to ra bng cch s dng mt b mt chia s gia ngi s dng di ng v HA ca h. Khi HA nhn c mt bn tin ng k, n phi kim tra trng nhn thc, nu nhn thy trng ny sai, yu cu b lai. 1.11.3. nh tuyn truyn tunnel ngc T hnh 1.14 ta thy nt di ng gi thng gi ca mnh n i tc theo a ch ngun khng hp l. Tin t mng ca gi ny l 128.4 v y l a ch mng nh ca my. Tuy nhin hin nay my ang nm ti mng c tin t 192.4.5 v v th cc a ch ny khng ging nhau. Cc thit b an ninh thng thng (tng la chng hn) s loi b cc gi c cc a ch ngun IP khng hp l. Bin php ny nhm bo v mng khi mt ngun pht tn cng DoS. trnh vn ny, ngi ta a ra s nh tuyn truyn tunnel ngc. Trong s ny, cc gi theo chiu ngc t my di ng n my i tc s c truyn tunnel t FA n HA. HA loi b tiu tunnel sau chuyn chng n ni nhn cui cng. 1.11.4. nh tuyn ti u T hnh 1.12 ta thy rng tuyn truyn cc gi t nt i tc n nt di ng l khng ti u. L do v nt i tc khng bit c CoA ca nt di ng. V th s nh tuyn ti u c xut. S ny cho php nt di ng cp nht trc tip

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rng buc CoA ca mnh cho nt i tc. Cc bc nh tuyn ti u c m t trn hnh 1.13.

Hnh 1.14. nh tuyn ti u trong MIP Cc bc nh tuyn ti u trn hnh 2.45 nh sau: 1. Gi u tin c gi t my i tc n HA sau HA chuyn n qua FA n

nt di ng 2. Nt di ng pht cp nht rng buc n my i tc cha rng buc gia CoA v

a ch nh ca n 3. My i tc gi cc gi thng n CoA ca ngi s dng Tuy nhin vic s dng nh tuyn ti u gp tr ngi v cc vn nhn thc. Cn nhn thc cp nht rng buc ( chng li cc tn cng DoS). Nu ta khng nhn thc cc cp nht ny, k tn cng c th gi n cc rng buc gi mo nh la my i tc v my ny s gi cc gi n a ch sai. Vic nhn thc gi nt di ng v HA l rt n gin: hai nt ny ch cn c lp cu hnh c chung mt b mt chia s. Nhn thc gia nt di ng m my i tc kh hn nhiu, v i tc c th l mt my bt k trn mng. Lp cu hnh hai nt ny cng c mt b mt chia s l iu khng thc t. Hin nay IETF ang nghin cu khc phc c an ninh cho nh tuyn ti u. 1.11.5. MIP cho IPv6 Trong MIPv6 khng cn s dng FA v chm sc a ch ng v tr (CCOA) ti my di ng c s dng thay cho COA. MIPv6 s dng ba bn tin sau: cp nht rng buc, bo nhn rng buc v yu cu rng buc. Cp nht rng buc c mc ch ging nh yu cu ng k nhng khng cha trng nhn thc. L do v bn thn IPv6 h tr nhn thc bng cch s dng

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IPSec trong tiu m rng (AH hay ESP). Cp nht rng buc c gi n cc tc nhn nh ca ngi s dng v chng cng c th c gi thng n my i tc ( t c nh tuyn ti u). Tuy nhin vn cn tn ti vn nhn thc cho nh tuyn ti u. L do v mt nt di ng ch c th gi cc cp nht rng buc n cc my i tc khi chng c th to lp mt lin kt an ninh IPSec. Mi cp nht rng buc c p li bng mt bo nhn rng buc m bo s tin cy. Cui cng, yu cu rng buc c my i tc gi i yu cu mt cp nht mi, th d, khi my i tc c mt CCOA cho nt di ng sp ht hn. Nt di ng s p li bng bng mt cp nht rng buc mi. Tm li, MIPv6 n gin v r m rng hn MIPv4. N s dng cc c ch an ninh c sn bn trong ca IPv6 (IPSec) v cha tiu chun nh tuyn ti u bn trong n. 1.11.6. Chuyn giao FA v MIP Khi mt nt di ng trong mng thng tin di ng di chuyn t mt FA ny sang mt FA khc, n phi tip xc vi FA ny v kt ni n HA phi c thit lp li. Tuy nhin lc u cc gi c th vn c th c chuyn n FA c v chng cha bit c CoA ca FA mi. m bo chuyn i m khng mt gi ta cn c h thng chuyn giao. trnh mt gi cn phi c mt thi gian chuyn i HA c th h tr cc ng k ng thi cho c hai FA. (xem hnh 1.15).

Bng rng buca ch nh CoA128.0.1.2 192.6.7.8128.0.1.2 192.9.5.4

Tc nhn ngoi

Tc nhn ngoi

Tc nhn nh

Node di ng128.0.1.2

Tc nhn nh c nhiu rng buc v s gi cc gi ti tc nhn ngoi

phc v c 2 . Hnh 1.15. Chuyn giao MIP C S trong yu cu ng k cho php HA h tr ng thi nhiu rng buc. C S c lp bng 1 ch th cho HA b sung thm mt rng buc mi nhng vn duy tr rng buc hin c. Th tc chuyn giao m nh sau:

1. Tip xc vi FA mi nhn c a ch CoA mi trc khi chuyn giao xy ra

2. ng k COA mi vi HA bng cch t bit S bng 1. Sau ng k, HA s chuyn cc gi n c hai t bo

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3. Sau khong thi gian qu chuyn giao n t bo mi, nt di ng ng k li CoA mi vi bit S t bng 0 loi b rng buc c.

1.11.7. MIP cho cdma2000 MIP c s dng trong cdma2000. FA c t ti PDSN v h tr cc chc nng chnh sau: nh tuyn n MS t HA nh tuyn ngc n HA Chuyn giao gia cc PDSN khng cn s tham gia ca mng nh Thit lp lin kt an ninh IPSec vi tc nhn nh n nh a ch nh ng Dch v AAA cho cc ngi s dng khch MIP trong cdma2000 cung cp chc nng ging nh GTP trong UMTS. C hai u h tr chuyn dch ngi s dng trong RAN m khng cn thay i a ch IP. im khc bit l ch MIP cho php ngi s dng chuyn dch ra ngoi mng TTD nhng vn duy tr kh nng kt ni. Tri li GTP tunnel ch tn ti trong mng ca nh khai thc v v th khng th h tr nh tuyn di ng khi ngi s dng ng nhp mng bng phng php khc vi GPRS. 1.11.8. MIP cho UMTS Nghin cu tnh kh thi khi s dng MIP trong UMTS h tr truyn tunnel v qun l di ng c th hin trong TS23.923 ca 3GPP. Khuyn ngh ny m t hai kin trc. Kin trc th nht xp chng MIP ln mng GPRS hin thi h tr di ng rng khp. Kin trc ny cho php lun lun ni c n ngi s dng cho d ngi ny s dng kt ni bng GPRS hay cc phng tin khc. y l mt kin trc MIP thng thng trong chc nng FA c t trong GGSN. Trong trng hp ny, GGSN pht i qung co khi nhn c yu cu PDP context. V khng phi mi GGSN u h tr di ng IP nn vic chn dch v ny da trn APN ca yu cu gc. Kin trc th hai thay th ton b GTP bng MIP. Trong trng hp ny SGSN v GGSN c kt hp vo mt nt h tr Internet GPRS (IGSN). IGSN s hot ng nh mt FA cung cp tunnel chuyn gi gia n v HA ca ngi s dng. TS 23.923 ch l mt nghin cu kh thi ch cha phi l mt yu cu bt buc i vi UMTS.

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1.12. CU HNH A L CA H THNG THNG TIN DI NG Do tnh cht di ng ca thu bao di ng nn mng di ng phi c t chc theo mt cu trc a l nht nh mng c th theo di c v tr ca thu bao. 1.12.1. Phn chia theo vng mng Trong mt quc gia c th c nhiu vng mng vin thng, vic gi vo mt vng mng no phi c thc hin thng qua tng i cng. Cc vng mng di ng c i din bng tng i cng GMSC. Tt c cc cuc gi n mt mng di ng t mt mng khc u c nh tuyn n GMSC. Tng i ny lm vic nh mt tng i trung k vo cho mng GSM/PLMN. y l ni thc hin chc nng hi nh tuyn cuc gi kt cui trm di ng. GMSC cho php h thng nh tuyn cc cuc gi vo t mng ngoi n ni nhn cui cng: cc tram di ng b gi. 1.12.2. Phn chia theo vng phc v MSC/VLR Mt mng thng tin di ng c phn chia thnh nhiu vng nh hn, mi vng nh ny c phc v bi mt MSC/VLR (hnh 1.16). Ta gi y l vng phc v ca MSC/VLR.

MSC1 VLR1

MSC3 VLR3

MSC2 VLR2

MSC4 VLR4

I II

III IV

Hnh 1.16. Phn chia mng thnh cc vng phc v ca MSC/VLR

nh tuyn mt cuc gi n mt thu bao di ng, ng truyn qua mng s c ni n MSC ang phc v thu bao di ng cn gi. mi vng phc v MSC/VLR thng tin v thu bao c ghi li tm thi VLR. Thng tin ny bao gm hai loi:

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