[Laptrinh.vn]-NC Wimax

8/4/2019 [Laptrinh.vn]-NC Wimax

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Nghin cu tiu chun 802.16e v ng dng trin khai trn mng ni ht

LI M U

Trong bi cnh s pht trin mnh m ca khoa hc cng ngh truyn thng v

tuyn bng rng qua khong cch xa, nhiu cng ngh ni ln nh chng t tim nng

v tnh kh thi ca mnh nh cng ngh DSL, ADSL, WiFi. Nhng cho ti nay tt cnhng cng ngh ny tuy hin nay rt ph bin nhng dng nh vn khng p ng

c nhu cu ngy cng cao ca ngi dng v mt tc , kh nng ph sng

WiMAX ni chung v c bit l WiMAX di ng ni ring vi nhng c tnh vt tri

chng t mnh l mt gii php tch cc c th gii quyt cc vn a truy nhp v

mt chi ph lp t, khong cch ph sng, tc ng truyn, ng thi thu ht c

s tham gia hp tc ca cc tp on in t ln trong vic sn xut thc y s hon

thin ca cng ngh mi ny.

ti kha lun tt nghip vi tiu : Nghin cu tiu chun 802.16e v ng

dng trin khai trn mng ni ht c thc hin nhm mc ch tm hiu tng quan

v cng ngh WiMAX di ng ng thi nghin cu tnh hnh trin khai ca cng ngh

mi ny trong iu kin thc t Vit Nam tr li cc cu hi nh: Ti sao cng ngh

mi ny li hp dn cc nh cung cp dch v v tuyn bng rng cng nh cc khch

hng nh vy? v Qu trnh trin khai trn thc t c thc hin nh th no, kt qu

thu c l g?. ng thi, vic nghin cu tm hiu v WiMAX di ng trong tnh hnh

mng vin thng Vit Nam hin nay l iu cn thit khng ch i vi th trng ni

chung cng nh cc cc nh qun l m quan trng hn s gip trang b cho sinh vin

khoa in t - vin thng ca trng i hc Cng Ngh nhng nn tng kin thc thc

t c bn v vic ng dng v pht trin cng ngh mi ny.

Trn c s nhng thng tin c sn t cc ti liu trong v ngoi nc, phn ni dung

ca bi vit c thc hin thng qua c v phn tch ng thi nu ln quan im ca

bn thn v nhng vn cn nghin cu. Ni dung bi kha lun bao gm 2 phn chnh:

Chng 1: Tng quan v chun 802.16e v WiMAX di ng.

Chng 2: Cc c tnh k thut ca WiMAX di ng.

Chng 3: ng dng trin khai WiMAX di ng trn mng ni ht ti Vit

Nam

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MC LC

LI M U............................................................................................................1

MC LC..................................................................................................................2-4

DANH MC HNH V.............................................................................................5-6

DANH MC BNG...................................................................................................7

THUT NG VIT TT.........................................................................................8-11

CHNG 1: TNG QUAN V CHUN 802.16e V WiMAX DI NG.........12

1.1 Gii thiu chung v WiMAX di ng ...................................................................12

1.2 M hnh h thng ..................................................................................................14

1.3 Kin trc mng WiMAX di ng..........................................................................15

1.4 K thut truyn thng s .......................................................................................16

1.4.1 M t lp vt l..........................................................................................16

1.4.1.1 Cc khi nim c bn v OFDM........................................................16

1.4.1.2 Cu trc k hiu OFDMA v knh con ha.......................................19

1.4.1.3 SOFDMA theo t l (S-OFDMA)......................................................22

1.4.1.4 So snh OFDM v OFDMA...............................................................23

CHNG 2: CC C TNH K THUT CA WIMAX DI NG...............26

2.1 Cu trc khung TDD.............................................................................................26

2.2 Cc c im lp PHY ci tin khc.....................................................................28

2.3 M t lp MAC (Media Access Control) ..............................................................30

2.3.1 Dch v lp lch MAC................................................................................32

2.3.2 H tr QoS ................................................................................................33

2.3.3 Qun l ngun............................................................................................35

2.3.4 Qun l di ng..........................................................................................36

2.3.5 Bo mt .....................................................................................................37

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2.3.6 Truy nhp knh truyn................................................................................38

2.4 Cc c im ci tin ca WiMAX di ng...........................................................39

2.4.1 Cng ngh anten thng minh.....................................................................39

2.4.1.1 MIMO ............................................................................................39

2.4.1.2 Cng ngh anten thng minh ..................................................................40

2.4.2 S dng li tn s phn on .....................................................................42

2.4.3 Dch v Multicast v Broadcast (MBS).....................................................44

2.5 Cc vn v ph ca WIMAX di ng...............................................................45

2.6 Kin trc WiMAX end-end...................................................................................46

2.6.1 H tr cc dch v v ng dng.................................................................48

2.6.2 Lin mng v chuyn vng .......................................................................48

2.6.3 Bo mt......................................................................................................51

2.6.4 Tnh di ng v chuyn giao......................................................................52

2.6.5 Kh nng m rng, vng bao ph v la chn nh khai thc.....................53

2.6.6 Kh nng lin hot ng ca a nh sn xut.............................................54

2.6.7 Cht lng dch v ....................................................................................54

CHNG 3: NG DNG TRIN KHAI WiMAX DI NG TRN MNG NI

HT TI VIT NAM ..............................................................................................55

3.1 Tng quan..............................................................................................................55

3.2 Trin khai WIMAX di ng ca cng ty Vin Thng H Ni (HNPT) ................56

3.2.1 Mc tiu trin khai.....................................................................................56

3.2.1.1 Yu cu v dch v cho h thng truy nhp v tuyn bng rng........563.2.1.2 i tng khch hng ca h thng truy nhp v tuyn bng rng...56

3.2.2 Qui m trin khai WIMAX di ng ti H Ni .........................................56

3.2.3 Phi hp th nghim trin khai Wimax gia Motorola v HNPT..............57

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3.2.3.1 Mc ch ca cuc Phi hp Th nghim Cng ngh (PTC).............59

3.2.3.2 Ni dung cng vic trin khai............................................................69

3.2.3.3 S chung v mng ca ULAP WiMAX .......................................70

3.2.3.4 Cc thnh phn h thng v thit b kim tra c yu cu...............71

3.2.3.4.1 Phn mm ...................................................................................72

3.2.4 Cu hnh th nghim .................................................................................73

3.2.4.1 Cc m hnh th nghim ...................................................................74

3.2.4.1.1 Dch v d liu ...................................................................74

3.2.4.1.2 Dch v thoi trn nn IP ...................................................75

3.2.4.1.3 Dch v game tng tc .....................................................77

3.2.4.1.4 Dch v mng ring o .......................................................78

3.2.4.1.5 Dch v cp pht a ch IP-DHCP ....................................79

3.2.4.1.6 Th nghim VOIP vi VOIP Server v Voice Gateway .... 80

3.2.5 Kt qu th nghim trin khai Wimax di ng ..........................................82

KT LUN CHUNG.................................................................................................83

TI LIU THAM KHO.........................................................................................84

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DANH MC HNH V

Hnh 1.1: Profile h thng WiMAX di ng

Hnh 1.2: L trnh pht trin cng ngh WiMAX

Hnh 1.3: M hnh h thng WiMAX

Hnh 1.4: Kin trc mng WiMAX di ng

Hnh 1.5: Phn chia lung s liu trong OFDM

Hnh 1.6: Mt ct ca Cyclic Prefix

Hnh 1.7: Mt ph nng lng ca tin hiu iu ch OFDM

Hnh 1.8: Min tn s OFDM

Hnh 1.9: M hnh knh con ha OFDM

Hnh 1.10: Cu trc sng mang con OFDMA

Hnh 1.11: S phn b pilot v d liu trong cc k hiu chn l

Hnh 1.12: Cu trc tile ca UL PUSC

Hnh 1.13: So snh OFDM v OFDMA

Hnh 1.14: Tng quan so snh gia OFDM v SOFDMA

Hnh 1.15: Tuyn ln trong OFDM v OFDMA

Hnh 2.1: Cu trc khung WiMAX OFDMA

Hnh 2.2: M hnh iu ch trong 802.16e

Hnh 2.3: Phn lp MAC v cc chc nng

Hnh 2.4: Qos h tr WiMAX di ng

Hnh 2.5: Cc bc kt ni vi trm BS

Hnh 2.6 : K thut MIMO

Hnh 2.7: Chuyn mch thch ng cho anten thng minh

Hnh 2.8 Cu trc khung a min

Hnh 2.9: S dng li tn s

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Hnh 2.10: H tr MBS nhng vi nhng vng WiMAX-MBS di ng

Hnh 2.11: M hnh tham chiu mng WIMAX

Hnh 2.12: Cu trc mng WiMAX trn nn IP

Hnh 3.1: S cc khu vc trin khai WiMAX di ng

Hnh 3.2: Cu hnh sn phm Ultra Light

Hnh 3.3: Cu hnh sn phm ULAP

Hnh 3.4: Framework qun l cc phn t ULAP

Hnh 3.5: Cu hnh cell in hnh (4 sector)

Hnh 3.6: Module thu bao ngoi tri

Hnh 3.7: Cu hnh a sector ca ULAP

Hnh 3.8: Cu hnh mng chung ULAP

Hnh 3.9: Cu hnh mng

Hnh 3.10: Cu hnh th nghim WiMAX di ng ca HNPT

Hnh 3.11: Th nghim dch v truyn file FTP

Hnh 3.12: Th nghim dch v duyt Web intranet

Hnh 3.13: Th nghim dch v duyt Web internet

Hnh 3.14: Th nghim dch v VOIP PC-to-PC

Hnh 3.15: Th nghim dch v Game trc tuyn

Hnh 3.16: Th nghim dch v mng ring o VPN

Hnh 3.17: SM built-in DHCP Server

Hnh 3.18: External DHCP Server

Hnh 3.19: Th nghim VOIP vi VOIP server (HNPT) v Voice Gateway (HNPT)

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DANH MC BNG

Bng 1.1: Cc tham s t l OFDMA

Bng 2.1: Cc k thut m ha v iu ch c h tr

Bng 2.2: Tc d liu PHY vi cc knh con PUSC trong WiMAX di ng

Bng 2.3: Cc dch v trong QoS

Bng 2.4: Cc ty chn ca Anten cao cp

Bng 2.5: Cc tc d liu cho cc cu hnh SIMO/MIMO

Bng 3.1: Tng hp nhng c tnh k thut chnh ca ULAP

Bng3.2: c tnh k thut v tuyn ca ULAP

Bng 3.4: c tnh k thut anten ca ULAP

Bng 3.5: Cc thng s k thut Module v Anten thu bao

Bng 3.6: Cc thng s k thut Module v Anten thu bao (tip...)

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CC K HIU VIT TT

AAA

Authentication, authorization and

Account

Nhn thc, cp php v lp

ti khon

ADSL Asymmetric Digital Subcriber Lineng dy thu bao bt i

xng

AES-CCMAES-CCM-based authenticated.

encryption

Thut ton bo mt m ho

nht thc

AMC Adaptive Modulation and Codingiu ch v m ha thch

ng

ARPU Average Revenue Per User Ch s doanh thu bnh qun

ca mt thu bao/thng

ASN gateway Access Service Network Mng dch v truy nhp

BS Base Station Trm gc

CCMPCipher Block Chaining Message

Authentication Code ProtocolGiao thc CCMP

CPS Common Part Sublayer Lp con phn chung

CQI Channel quality indicator Ch th cht lng knh

CQI Channel quality indicator Mt knh ch th cht lng

knh

CS Convergence Sublayer Lp con hi t

CSN Core Service Network Mng dch v li

DHCP Dynamic Host Configuration ProtocolGiao thc cu hnh Host

ng

DL Downlink ng xung

DL FUSC Fully Used Sub-Carrier Sng mang con s dng hon

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ton

DL PUSC Partially Used Sub-Carrier Sng mang con s dng mt

phn

DOCSISData Over Cable Service InterfaceSpecification

Dch v truyn data bngng cp

DSL Digital Subcriber Line Knh thu bao s

EAP Extensible Authentication ProtocolGiao thc xc thc c th m

rng

EAP Extensible Authentication Protocol Giao thc xc thc m rng

FBSS Fast Base Station Switching Chuyn mch trm gcnhanh

FCH Frame Control Header Tiu iu khin khung

FDMAFrequence Division Mutiplexing

Access

a truy nhp phn chia theo

tn s

HARQHybrid Automatic Retransmission

Request

Yu cu truyn li t ng

kt ni

HHO Hard Handoff Handoff cng

HMAC Hashed Message Authentication CodeKha m nhn thc bn tin

bm

IEEEInstitute of Electrical and Electronics

Engineers

Vin cc k s in v in

t

LOS Line of sight Tm nhn thng

MAI Multi Access Interfearence Nhiu a truy xut

MDHO Macro Diversity Handover Handover chuyn giao phn

tp v m

MIMO Multiple-input and multiple-output K thut s dng nhiu ng-

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ten pht v nhiu ng-ten thu

truyn v nhn d liu

MS Mobile Station Trm di ng

NAP Network Access Provider Nh cung cp truy nhpmng

NOSL None-light of sight Khng theo tm nhn thng

NRM Network Reference Model M hnh tham chiu mng

NSP Network Service Provider Nh cung cp dch v mng

OFDMOrthogonal Frequency Division

Multiplexing

Ghp knh phn chia theo tn

s trc giao

OFDMAOrthogonal Frequency Division

Multiple Access


tn s trc giao

PKM Protocal of Key Management Phng thc qun l kha

QoS Quality of Service Cht lng dch v

QPSK Quadratura Phase Shift Keying Kha chuyn pha cu phng

RTG Receive Transition Gap Khong trng chuyn giaou thu

RUIM Removable User Identity ModuleM un xc nhn ngi s

dng c th di chuyn c

SAP Service Access Point im truy nhp dch v

SDU Service Data Unit n v d liu dch v

SFN Single Frequency Network Mng mt tn sSIM Subscriber Identity Module M dun xc nhn thu bao

SNMP Simple Network managementGiao thc qun l mng

Protocol n gin

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SOFDMAScalable Orthogonal Frequency

Division Multiplexing

Ghp knh phn chia theo tn

s trc giao theo t l

SSCSSpecify Services Convergence

Sublayer

Lp con hi t cc dch v

ring

TDMATime Division

Multiplexing Access


thi gian

TTG Transmit Transition GapKhong trng chuyn giao

u pht

UL Uplink ng ln

ULAP Ultra Light Access Point im truy cp

WAC Wireless Access Controlleiu khin truy cp khng

dy

WiMAXWorldwide Interoperability for

Microwave Access

Kh nng tng tc ton cu

vi truy nhp vi ba

CHNG 1: TNG QUAN V CHUN 802.16E V WiMAX DI NG

1.1 Gii thiu chung v WiMAX di ng

WiMAX (Worldwide Interoperability for Microwave Access - Kh nng tng tc

ton cu vi truy nhp vi ba) l mt cng ngh ra i da trn cc chun 802.11 v

802.16 ca IEEE (Institute of Electrical and Electronics Engineers Vin cc k s in

v in t) cho php truy cp v tuyn u cui nh mt phng thc thay th cho cp,

DSL, ADSL hoc h thng cp quang tn km. H thng WiMAX, theo nh WiMAX

Forum, cho php kt ni bng rng v tuyn c nh, nomandic - trong ngi s dng

c th di chuyn nhng c nh trong lc kt ni, mang xch c trong ngi sdng c th di chuyn tc i b, di ng vi kh nng ph sng ca mt trm anten

pht ln n 50 km di cc iu kin tm nhn thng (LOS Line of sight) v bn knh

cell ln ti 8km khng theo tm nhn thng (NLOS Non line of sight).

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Trong h IEEE 802.16 ni bt nht l chun 802.16e 2005 vi kh nng p ng

cc ng dng c nh v c bit l cc dch v di ng, nn cn c gi l WiMAX di

ng. Chun ny nh du s pht trin vt bc trong kh nng p ng nhu cu s

dng ngy cng cao ca ngi dng. Vi nhng thuc tnh vt tri c bit v tc

ng truyn s liu ln ti 64Mbps downlink v 28Mbps uplink kh nng cung ng ding ti a ln ti 120km/h, v bn knh ph ln ti 1/5/30km, WiMAX di ng ang dn

chng t mnh l mt cng ngh quan trng trong lnh vc cung cp gii php Internet

bng rng di ng v l mt i th cnh tranh ng gm i vi mng thng tin di ng

3G LTE trong vic cung ng cc dch v tng t nh thoi VoIP, Internet di ng hay

TV di ng.

WiMAX di ng s l mt gii php v tuyn bng rng cho php hi t mng bng

rng c nh v di ng thng qua cng ngh truy nhp v tuyn bng rng trn din rng

v kin trc mng mm do. Giao din v tuyn WiMAX di ng s dng phng thc

a truy nhp chia theo tn s trc giao (OFDMA) ci thin vn a ng trong mi

trng NLOS. Phng thc OFDMA scalable (SOFDMA) c s dng trong bn b

xung IEEE 802.16e h tr bng tn knh thay i t 1.25 ti 20 Mhz. Hin nay, mt

profile h thng WiMAX di ng ang c pht trin nhm xc nh cc c im bt

buc v tu chn ca chun IEEE xy dng cc giao din v tuyn tun theo WiMAX

di ng. Profile h thng WiMAX di ng ny cho php h thng di ng c cu hnh

da trn tp hp cc c im chung do m bo cc cho u cui v trm gc c thlin hot ng. Mt vi c im tu chn ca profile trm gc c a ra nhm to nn

s mm do trong vic trin khai cc cu hnh khc nhau vi iu kin hoc ti u v kh

nng hoc v vng ph. Profile WiMAX di ng s bao gm rng knh 5, 6, 8.75 v

10 MHz trong bng tn s 2.3 GHz, 2.5 GHz v 3.5 GHz 002E

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Hnh 1.1: Profile h thng WiMAX di ng

Hin nay, mt nhm lm vic mng ca din n WiMAX ang pht trin cc tiu

chun k thut mng mc cao cho h thng WiMAX di ng m trong chun IEEE

802.16 mi ch gii quyt cc vn n gin ca cc phn giao din v tuyn. Nhm

ny cng ang nghin cu phin bn khc l 802.16m vi mc ch y tc d liu

ca WiMAX ln hn na trong khi vn tng thch vi WiMAX c nh v di ng v

ang c trin khai. Phin bn ny theo d kin s c hon thin vo cui nm 2009,

nh l mt bc tin vt tri hn 3G LTE v xm nhp su rng hn vo th trng

di ng hin nay. Phin bn 802.16m s vn da trn k thut ng-ten MIMO trn nn

cng ngh a truy nhp OFDMA vi s lng ngten pht v thu nhiu hn WiMAX di

ng Wave 2 . 802.16m trang b 4 ng-ten pht v 4 ng-ten thu s c th y tc truyn ln ln hn 350Mbps. Theo d kin,WiMAX Release 2 vi s hon thin ca

802.16m s hon thnh vo cui nm 2009 v c th bt u trin khai dch v t 2010.

Hnh 1.2 di y th hin l trnh pht trin ca cng ngh WiMAX , ang v s xut

hin .

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Hnh 1.2: L trnh pht trin cng ngh WiMAX

1.2 M hnh h thng

M hnh ph sng mng WiMAX hay WiMAX di ng tng t nh mt mng in

thoi di ng vi 2 phn: Trm pht v Trm thu.

Trm pht: Ging nh cc trm BTS trong mng thng tin di ng vi cng sut

ln, c th ph sng khu vc rng ti 8000 km2

Trm thu: C th l cc anten nh nh cc loi card mng tch hp hoc c gn

thm trn mainboard ca my tnh nh card WLAN.

Ngi dng c th truy cp WiMAX di ng ti bt c a im no d l c nh

hay ang di ng. Mt im ng ch l cc trm pht do c kt ni vi mng

Internet thng qua cc ng truyn Internet tc cao hoc cc trm trung chuyn theo

ng truyn thng LOS nn kh nng ph sng ca WiMAX l rt rng. Cc anten thu

pht c th trao i thng tin qua cc ng truyn LOS hoc NLOS. i vi trng hp

truyn thng LOS, cc anten c t c nh ti cc im trn cao do vy tn hiu thuc trong trng hp ny rt n nh v t tc truyn ti a. Tuy nhin i vi

trng hp truyn NLOS, h thng s dng bng tn thp hn, 2 11 GHz tng t nh

WLAN, tn hiu c th vt cc vt chn thng qua ng phn x, nhiu x, tn x

ti ch.

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Hnh 1.3: M hnh h thng WiMAX

1.3 Kin trc mng WiMAX di ng

Hnh 1.4: Kin trc mng WiMAX di ng

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Ta thy thit lp mt mng WiMAX hay WiMAX di ng ta cn c cc trm

pht BS (ging BTS ca mng thng tin di ng). Nhiu BS s c kt ni, qun l bi

mt ASN (Access Service Network) gateway. ASN Gateway ny l thc th miu t trong

WiMAX Forum, tuy nhin trong cc mng trin khai thc t th ngi ta hay gi l WAC

(WiMAX hay Wireless Access Controller). Nhiu WAC tp hp li to thnh mt ASN.Nhiu ASN ca cng mt operator to thnh mt NAP (Network Access Provider). Nhiu

nh cung cp khc nhau s c th trin khai nhiu mng truy nhp khc nhau, ri chng s

cng kt ni vi mt hoc nhiu CSN (Core Service Network).

ASN nh ngha mt ng bin logic v biu din theo mt cch thun li m t

tp hp cc thc th chc nng v cc lung bn tin tng ng kt hp vi cc dch v

truy cp. ASN biu din ng bin cho chc nng lin kt ni vi cc mng WiMAX

khch, cc chc nng dch v kt ni WiMAX v tp cc chc nng ca nhiu nh cung

cp khc nhau. CSN c nh ngha l mt tp cc chc nng mng cung cp cc dch

v kt ni IP cho cc thu bao WiMAX. Mt CSN c th gm cc phn t mng nh

router (b nh tuyn), my ch/proxy nhn thc AAA, c s d liu ngi dng v thit

b cng lin mng. Mt CSN c th c trin khai nh mt phn ca nh cung cp dch

v mng WiMAX.

1.4 K thut truyn thng s

1.4.1 M t lp vt l

1.4.1.1 Cc khi nim c bn v OFDM

Cng ngh WiMAX di ng chn phng php truy cp a im da trn vic phn

chia tn s trc giao (Orthogonal Frequency Division Multiple Access - OFDMA)

nng cao hiu sut truyn gia cc im trong mi trng khng pht sng trc tip. Tuy

nhin hiu r v OFDMA th vic tm hiu nhng nt c bn v OFDM l rt cn thit.

OFDM l cng ngh ghp knh phn chia theo tn s trc giao-mt k thut hp dn

s dng cho cc h thng truyn thng s liu tc cao. N c pht trin t 2 k thut

quan trng l ghp knh phn chia theo tn s (FDM) v truyn thng a sng mang.

OFDM l mt k thut ghp knh m chia bng tn thnh cc tn s sng mang nh nh

c ch ra trong hnh sau :

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http://tudiencongnghe.com/Special:Search/BShttp://tudiencongnghe.com/Special:Search/BTShttp://tudiencongnghe.com/Special:Search/WiMAX%20Forumhttp://tudiencongnghe.com/Special:Search/IPhttp://tudiencongnghe.com/Special:Search/BShttp://tudiencongnghe.com/Special:Search/BTShttp://tudiencongnghe.com/Special:Search/WiMAX%20Forumhttp://tudiencongnghe.com/Special:Search/IP


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Hnh 1.5: Phn chia lung s liu trong OFDM

Trong h thng OFDM, lung s liu u vo c chia ra thnh cc lung con song

song vi tc s liu nh hn v nh vy tng khong thi gian ca k hiu v milung nh c iu ch v truyn trn mt sng mang trc giao. Hn na, s s dng

tin t lp-CP (cyclic frefix) c th hon ton loi tr xuyn nhiu gia cc k hiu (ISI)

min l thi lng CP lu hn tr knh lan truyn. CP l mt s lp li ca mt on cui

ca khi s liu v c gn ti u ca on ti s liu nh c ch ra trong hnh:

Hnh 1.6: Mt ct ca Cyclic Prefix

S dng CP chng li xuyn nhiu gia cc k hiu v to cho knh xut hin

vng trn. Mt trong nhng nhc im ca CP l lm gim hiu qu ca bng thng dos dng thm phn tiu . CP lm gim hiu qu s dng bng thng i mt t. Do ph

OFDM c hnh rt nhn ging nh brick-wall, do mt phn ln bng thng knh

c s dng cho truyn s liu nn gip gim nh hng trong vic s dng tin t vng

trn.

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Hnh 1.7: Mt ph nng lng ca tn hiu iu ch OFDM

OFDM c th trin khai trn nhiu di tn s khc nhau vi a knh bng cch s

dng m ho v thng tin ti sng mang nh trc khi a vo truyn dn.

Hnh 1.8: Min tn s OFDM

iu ch OFDM c th hin thc ho mt cch hiu qu vi chuyn i Fourier

ngc nhanh. iu ny cho php truyn mt s lng ln cc sng mang nh m khng

phc tp trong vic thc hin. Trong mt h thng OFDM, cc ti nguyn trong min thigian chnh l cc k hiu OFDM v trong min tn s l cc sng mang nh. Ngun ti

nguyn tn s v thi gian c th c t chc thnh cc knh con dng cho vic

phn b ti tng ngi s dng ring r. Mi hnh ch nht l mt knh con c lp v

cp cho nhng ngi s dng khc nhau:

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Hnh 1.9: M hnh knh con ha OFDM

1.4.1.2 Cu trc k hiu OFDMA v knh con haOFDMA (Orthogonal Frequency Division Multiplexing Access) l mt phng thc a

truy nhp phn chia theo tn s trc giao, cung cp hot ng ghp knh lung s liu cho

a ngi s dng vo cc knh con ng xung v a truy nhp ng a ng ln

bng phng tin knh con ng ln.

OFDMA l mt cng ngh a sng mang pht trin trn nn k thut OFDM. Trong

OFDMA, mt s sng mang con, khng nht thit l phi nm k nhau c gp li thnh

mt knh con (sub-channel) v cc user khi truy cp vo ti nguyn s c cp cho mthay nhiu knh con truyn nhn ty theo yu cu lu lng c th.

OFDMA c mt s u im nh l tng kh nng linh hot, thng lng v tnh n

nh c ci thin. Vic n nh cc knh con cho cc thu bao c th, vic truyn nhn

t mt s thu bao c th xy ra ng thi m khng cn s can thip no, do s gim

nhng tc ng nh nhiu a truy xut (Multi Access Interfearence-MAI).

OFDMA cho php nhiu ngi dng truy nhp cc sng mang con cng mt lc.

mi n v thi gian, tt c cc ngi dng c th truy nhp. Vic n nh cc sng mang

con cho mt ngi dng c th thay i mi n v thi gian.

Cu trc k hiu OFDMA bao gm 3 kiu sng mang con nh c ch ra trong

hnh sau:

Sng mang con s liu cho truyn dn s liu

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Sng mang con dn ng cho mc ch c lng v ng b ho

Sng mang con Null khng truyn dn truyn, c s dng cho phn bng

thng an ton v ti mang DC.

Hnh 1.10: Cu trc sng mang con OFDMA

Sng mang con (s liu v pilot), c nhm thnh tng nhm sng mang con cgi l knh con. WiMAX OFDMA lp vt l h tr knh con ho trong c DL v UL.

Khi ngun ti nguyn thi gian-tn s ti u cho knh con ho l mt khe, bng 48 tone

s liu (sng mang con).

C 2 kiu hon v sng mang con cho knh con ho: phn tn v k nhau. S hon v

phn tn dn n cc sng mang con gi ngu nhin hnh thnh mt knh con. S hon

v ny mang n tnh a dng tn s v trung bnh xuyn nhiu gia cc cell. S hon v

phn tn bao gm DL FUSC (Sng mang con s dng hon ton), DL PUSC (Sng mang

con s dng mt phn), UL PUSC v cc hon v tu chn thm. Vi DL PUSC, mi cp

k hiu OFDM, cc sng mang con c th s dng hoc kh dng c nhm thnh cc

cluster cha 14 sng mang lin k trn mt k hiu, vi s phn b pilot v s liu trn

mi nhm trong cc k hiu chn v l nh hnh sau..

Hnh 1.11: S phn b pilot v d liu trong cc k hiu chn l

- 20 -


21/85


Mt nguyn l sp xp li c s dng hnh thnh nhm cc cluster. Mt knh

con trong nhm cha 2 cluster v c c to bi 48 sng mang con s liu v 8 sng

mang con pilot. Cc sng mang con s liu trong mi nhm c tip tc hon v to

thnh cc knh con trong phm vi nhm. V vy, ch cc v tr dn ng trong cluster l

c biu th trong hnh trn.Cc song mang con d liu trong cluster c phn b chonhiu knh con.

Tng t vi cu trc nhm cho DL, mt cu trc tile c xc nh cho UL PUSC

c nh dng nh hnh 1.12

Hnh 1.12: Cu trc tile ca UL PUSC

Khng gian sng mang con hiu dng c chia thnh cc tile, c chn t ph

bng s hon v/ sp xp li, c nhm cng nhau hnh thnh mt khe. Khe bao

gm 48 sng mang s liu v 24 sng mang pilot trong 3 k hiu OFDM.Hon v lin k nhm mt khi cc sng mang con lin k hnh thnh knh con.

Hon v lin k bao gm DL AMC v UL AMC, v c cng mt cu trc. Mt thng

(bin) bao gm 9 sng mang con trong mt k hiu, vi 8 c gn cho s liu v mt

c gn cho pilot. Mt khe (slot) trong AMC c xc nh nh l mt tp hp cc

thng vi kiu (N*M=6), trong N l s thng lin k v M l s k hiu lin k. Do ,

cc kiu hon v ny c th l (6 bin, 1 k hiu, 3 bin, 2 k hiu, 1 bin 6 k hiu). Hon v

AMC cho php nhiu ngi s dng bng cch chn knh con vi s phn hi tn s tt

nht.

Ni chung, kiu hon v sng mang con a dng thc hin tt trong cc ng dng di

ng trong khi hon v sng mang con lin k li ph hp tt cho mi trng di ng

thp, hoc c th lu ng hoc c nh. Nhng tu chn ny cho php ngi thit k h

thng la chn ra kiu hon v ph hp vi h thng ca mnh.

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1.4.1.3 S-OFDMA theo t l

y l mt c im b xung cho IEEE 802.16e h tr chuyn giao d dng.

Trong OFDM-TDMA v OFDMA, s lng sng mang con thng c gi bng

nhau vi ph c sn. S sng mang con khng thay i dn n khng gian sng mangcon thay i trong cc h thng khc nhau. iu ny lm cho vic chuyn giao gia cc

h thng gp kh khn. Ngoi ra, mi h thng cn mt thit k ring v chi ph cao.

OFDMA theo t l (S-OFDMA) gii quyt cc vn ny bng cch gi cho khng

gian sng mang con khng thay i. Ni cch khc, s sng mang con c th tng hoc

gim vi nhng thay i trong mt bng tn cho trc. V d, nu mt bng tn 5MHz

c chia thnh 512 sng mang con, mt bng tn 10MHz s c chia thnh 1024 sng

mang con.

Bi v khng gian sng mang con l gi nguyn trong S-OFDMA nn mt my di

ng c th chuyn giao gia cc h thng mt cch sun s. Ngoi ra, vi khng gian

sng mang con khng thay i, mt thit k l ph hp cho nhiu h thng v c th ti

s dng. Chi ph cho thit k v sn phm s thp hn.

C th hn th S-OFDMA h tr mt khong rng bng thng gii quyt mt

cch mm do vic phn chia ph thay i v p ng cc yu cu khc hu ch.

Scalability thc hin c do iu chnh kch thc FFT trong khi vn c nh khong

cch tn s cho mt sng mang l 10.94 kHz. Do bng thng sng mang con v dica k t l c nh, tc ng ti lp cao hn l nh khi thay i bng tn. Cc tham s S-

OFDMA c m t trong bng. Bng tn h thng ca profile ban u c pht trin

bi nhm lm vic v k thut vi phin bn-1 l 5 v 10 MHz (c t sng trong bng)

Bng 1.1: Cc tham s t l OFDMA

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1.4.1.4 So snh OFDM v OFDMA

Theo k thut ghp knh c bn th OFDM c s dng cho nh dng 802.16

2004 rt ph hp vi cc ng dng c nh, trong khi chun 802.16e li s dng OFDMA

li c bit thch hp vi mc ch ng dng trong di dng v v bn cht OFDM t phc

tp hn so vi SOFDMA.

Hnh 1.13: Tng quan so snh gia OFDM v SOFDMA

OFDMA to cho cc nh dng 802.16e linh hot hn rt nhiu trong vic qun l

cc dch v ngi dng khc nhau vi nhiu kiu anten v yu t hnh dng khc nhau.

N em li s gim bt can nhiu cho cc thit b khch hng c anten ton hng v kh

nng truyn NLOS c cai thin nhng yu t rt cn thit khi h tr cc thu bao di

ng. Vic to knh ph thuc s xc nh cc knh con c th gn cho cc thu baokhc nhau ty thuc vo cc trng thi knh v cc yu cu d liu ca chng. iu ny

to iu kin cho cc nh khai thc linh hot hn trong vic qun l bng thng v cng

sut pht, t dn n vic s dng ti nguyn hiu qu hn.

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Hnh 1.14: So snh OFDM v OFDMA

Trong OFDM, tt c cc sng mang u c pht i mt cch song song vi cng

mt bin trong khi OFDMA chia khng gian sng mang thnh NG nhm mi nhm c

NE sng mang v NE knh con, mi knh con ny mang mt sng mang cho mi nhm.

Vic to knh con ny gip ci thin hiu nng khi cng sut pht t mt thit b ngi

dng b hn ch. Chng hn trong OFDMA c 2048 sng mang bin i thnh N E = 32 v

NG = 48 trong tuyn xung v NG = 53, NE =32 trong tuyn ln vi cc sng mang cn li

c dng cho cc bng bo v v bo hiu.

Trong OFDM, cc thit b ngi dng pht i bng cch s dng ton b mt knh

cng mt lc nh hnh v bn di. Trong khi , OFDMA h tr a truy nhp cho php

ngi dng ch pht i qua cc knh con c gn cho chng. Nh v d trn, nu 2048

sng mang v 32 knh con, nu ch mt knh con c gn cho mt thit b th ton b

cng sut pht ra s c tp trung trong 1/32 ph kh dng v c th em li mt li

15dB so vi OFDM. Hn th na, hnh thc a truy nhp ny l c bit c li khi s

dng cc knh rng.

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Hnh 1.15: Tuyn ln trong OFDM v OFDMA

Trong OFDM, cc thit b ngi dng c gn cc khe thi gian pht, nhng

ch mt thit b ngi dng c th pht trong mt khe thi gian duy nht. Trong OFDMA,

vic to knh con cho php mt s thit b c pht trong cng mt thi gian qua cc

knh con c gn cho chng.

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CHNG 2: CC C TNH K THUT CA WiMAX DI NG

2.1 Cu trc khung TDD

PHY 802.16e h tr TDD, FDD v hot ng FDD half-duplex. Tuy nhin, phin

bn ban u ca profile chng ch WiMAX di ng ch c vi ch TDD. Vi phinbn ang c nghin cu, profile FDD s c xem xt bi din n WiMAX to ra

cc c hi kinh doanh mi cho nhng ni c cc yu cu v ph ni ht hoc cm i vi

TDD hoc l ph hp hn vi trin khai FDD.

TDD l mt ng dng ca a truy nhp phn chia theo thi gian TDMA (Time

Devision Multiple Acces) phn tch tn hiu i v tn hiu v. TDD c mt tin ch ln

trong trng hp s khng i xng gia tc uplink v v downlink d liu l thay

i. Khi s liu uplink tng ln th s c mt di thng rng hn c th phn phi cho n

nh trc khi n c co li c th truyn i. Mt tin ch khc khin TDD c s

dng trong WiMAX di ng th h u l ng tn hiu radio uplink v downlink l rt

ging trong h thng di chuyn chm iu c ngha l cng ngh nh beamforming

lm vic rt tt vi h thng TDD. S sp xp c h thng ca TDD c th cp pht mt

cch linh hot s lng khe thi gian cho hai chiu truyn v nhn d liu, iu ny c

bit quan trng trong cc ng truyn Internet vi t l UL/DL khng b bt buc phi l

50/50. Xt mt cch tng qut th TDD c th mang li s linh hot cng nh gip nng

cao nng lc ca h thng ln rt nhiu. Tuy nhin, vic s dng TDD trong phin bn

u ny ca WiMAX di ng gp phi mt nhc im l b hn cht bi di tn nh.

hiu qu TDD chia dng d liu ra thnh nhiu khung v vi mi khung ny li

chia thnh cc khe thi gian truyn i v nhn v.

i vi vn xuyn nhiu, TDD khng yu cu s ng b h thng din rng,

tri li TDD s u tin ch song cng v nhng l do sau:

TDD cho php iu chnh t s ng xung/ng ln h tr lu lng ng

xung/ng ln mt cch hiu qu, trong khi vi FDD, ng xung v ng

ln lun lun b c nh v ni chung l bng vi bng thng DL v UL.

TDD m bo s trao i knh : h tr kh nng iu chnh ng truyn,

MIMO v cc cng ngh anten ci vng kn cao cp khc.

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Khng ging nh FDD vi vic yu cu mt cp knh, TDD ch yu cu mt knh

n cho c ng xung v ng ln, iu ny dn n mm do hn i vi s

phn chia ph thay i.

Thit k b thu pht trin khai TDD l t phc tp hn v do s tn km hn.

Hnh v di y minh ho cu trc khung OFDM vi phng thc song cng chia

theo thi gian (TDD). Mi khung c chia thnh khung con DL v UL ring r bi cc

b chuyn dch pht/thu v thu/pht (TTG v RTG tng ng) chng li s xung t

trong truyn dn DL v UL. Trong mt khung, thng tin iu khin sau c s dng

m bo hot ng h thng ti u:

Phn u khung (preamble): c s dng cho ng b, l k hiu OFDM u

tin ca khung.

Tiu iu khin khung (FCH):FCH c t ngay sau phn m u

(preamble). N cung cp cc thng tin cu hnh khung nh di bn tin MAP, s

m ho v knh con hiu dng.

DL-MAP v UL-MAP: Cung cp s phn b knh con v thng tin iu khin

khc cho khung con DL v UL mt cch tng ng.

Khong UL: Knh con UL c s dng cho trm gc di ng (MS) thc hin

thi gian vng kn, tn s v s iu chnh cng xut cng nh yu cu bng tn.

UL CQICH: Knh UL CQICH c phn b cho MS tr li li cc thng tin

v trng thi knh.

UL ACK: c s dng cho MS tr li li thng bo DL HARQ.

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Hnh 2.1: Cu trc khung WiMAX OFDMA

2.2 Cc c im lp PHY ci tin khc

WiMAX di ng a ra cc k thut: iu ch thch nghi v m ha (AMC), yu

cu lp li t ng li kiu kt hp (HARQ), v phn hi knh nhanh (CQICH), tng

cng kh nng ph sng v kh nng ca WiMAX trong cc ng dng di ng.

Trong WiMAX di ng ng xung, bt buc phi c cc h tr iu ch QPSK,

16 QAM v 64 QAM, cn ng ln 64 QAM l ty chn.

Hnh 2.2: M hnh iu ch trong 802.16e

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29/85


C m ha vng v m ha Turbo vng vi tc m thay i v m lp cng c

h tr. Ngoi ra, m Turbo v m kim tra chn l mt thp (LDPC) cng c h tr

ty chn. Bng sau tng kt cc nguyn l m ha v iu ch c h tr trong profile

WiMAX di dng (vi m UL tu chn c ch ra vi ch in nghing).

Bng 2.1: Cc k thut m ha v iu ch c h tr

S t hp cc k thut iu ch v cc tc m em li s tinh phn gii tc d

liu nh minh ha trong bng 1.3 (vi rng knh l 5 v 10 MHz vi cc knh con

PUSC). di khung l 5ms. Mi khung c 48 biu trng OFDM gm 44 biu trng sn

sng truyn d liu. Cc gi tr nh du mu l ch cc tc cho k thut 64QAM

ty chn ng ln.

Bng 2.2: Tc d liu PHY vi cc knh con PUSC trong WiMAX di ng

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B lp lch trm gc xc nh tc d liu ph hp mi cp pht cm (burts) da

trn kch thc b m v iu kin truyn song pha thu...Mt knh ch th cht lng

knh (CQI-channel quality indicator) c s dng cung cp thng tin trng thi knh

t thit b u cui ngi s dng n b lp lch trm gc. Thng tin trng thi knh c

th c phn hi bi CQICH bao gm: CINR vt l, CINR hiu qu, s la chn ch MIMO v s la chn knh con. Vi k thut TDD, thch ng ng truyn cng c th

tn dng u im ca vic o knh cung cp vic o chnh xc hn (nh l m thanh).

WiMAX di ng cng h tr HARQ. HARQ cho php s dng giao thc dng v

i N knh cung cp kh nng p ng nhanh ng gi li v ci tin kh nng ph

sng ng bin cell. S d tha tng c h tr ci tin hn v tin cy ca vic

truyn li. Mt knh ACK cng c cung cp trong ng uplink cho tn hiu HARQ

ACK/NACK. HARQ kt hp vi CQICH v AMC cung cp s tng thch lin kt manh

trong mi trng ti tc phng tin qu 120Km/gi.

2.3 M t lp MAC

Chun 802.16 c pht trin t yu cu v vic cung cp a dng dch v bng

rng bao gm thoi, d liu, v video. Lp MAC l hng kt ni bao gm ba phn lp

con. Lp con hi t dch v ring (SSCS) cung cp mi s bin i hay nh x d liu

mng ngoi, nhn d liu mng ngoi qua im truy nhp dch v CS SAP, cc MAC SDU

(n v d liu dch v) c nhn bi lp con phn chung MAC CPS thng qua MAC

SAP.

Bao gm vic phn loi cc SDU mng ngoi v kt hp chng vi nhn dng lung

dch v MAC thch hp (SFID) v nhn dng kt ni (CID). N c th cng bao gm cc

chc nng nh nn tiu ti trng (PHS). Nhiu chi tit k thut CS c cung cp cho

giao din vi nhiu loi giao thc. nh dng bn trong ca ti trng CS l duy nht vi

mi CS, v cc MAC CPS khng yu cu hiu dc nh dng ca n hay phn tch bt k

thng tin no t ti trng CS.

MAC CPS cung cp cc chc nng MAC chnh ca vic truy nhp h thng, cp pht rng di tn, thit lp v duy tr kt ni. N nhn d liu t nhiu CS thng qua MAC

SAP, phn loi thnh cc kt ni MAC c th. QoS c p dng cho vic truyn v lp

lch d liu thng qua lp PHY s dng 4 loi dch v c bn.

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C hai loi kt ni l cc kt ni qun l v kt ni truyn ti d liu. Cc kt ni

qun l c ba loi: c bn, s cp v th cp. Mt kt ni c bn c to ra cho mi MS

khi n gia nhp vo mng. Kt ni s cp cng c to ra cho mi MS thi im vo

mng nhng uc dng cho cc bn tin qun l dung sai tr. Loi kt ni qun l th ba,

loi th cp c dng cho cc bn tin qun l IP tm lc (nh DHCP, SNMP, TFP).Cc kt ni truyn ti d liu c th c cung cp hoc c thit lp theo yu cu.

Chng c dng cho cc lung lu lng ngi dng. n im hoc a im c th

c dng cho truyn dn.

2.3.1

Dch

v

lp

lchMAC

- 31 -

Thc th qun lLp con phn chung MAC

Lp con bo mt

Thc th qun lPHY

Thc th qun l

Lp con hi t dch vc bit SSCS

Hthngq

unlm

ng

PHY SAP

MAC SAP

CS SAP

Lp con phn chungMAC (MAC CPS)

Lp con bo mt(MAC SS)

Lp vt l (PHY)

Lp con hi t dch vc bit (MAC SSCS)

PHY

MAC

mt bngd liu/ iu khin

Mt bng qun l

Quy m chun ha

Hnh 2.3: Phn lp MAC v cc chc nng


32/85


Dch v lp lch MAC WiMAX di ng c thit k phn pht hiu qu cc dch

v s liu bng rng bao gm thoi, d liu, v video vi knh v tuyn bng rng thay

i theo thi gian. Dch v lp lch MAC c cc thuc tnh sau:

B lp lch s liu nhanh: B lp lch MAC phi phn b hiu qu ngun ti

nguyn kh dng p ng li vi lu lng s liu bursty v iu kin knh thay

i theo thi gian. B lp lch ngi ti mi trm gc cho php phn hi nhanh hn

vi yu cu lu lng v iu kin knh. Gi s liu c a vo cc lung dch

v vi tham s QoS trong lp MAC ngi lp lch c th quyt nh trt t

truyn gi qua giao din v tuyn. Knh CQICH cung cp phn hi thng tin knh

nhanh cho php b lp lch la chn m ho thch hp v iu ch cho mi trm

gc. iu ch/ m ho thch ng kt hp vi HARQ cung cp truyn dn mnh qua

knh thay i theo thi gian.

Lp lch cho c DL v UL: Dch v lp lch c cung cp cho c lu lng DL

v UL. b lp lch MAC phn b ngun ti nguyn hiu qu v cung cp QoS

mong mun trong UL, UL phi phn hi chnh xc v thng tin kp thi i vi

kha cch iu kin lu lng v yu cu v QoS. Cc c ch yu cu bng tn a

ng ln nh l yu cu bng tn thng qua mt khong knh, yu cu

piggyback v polling c thit k h tr yu cu bng tn UL. Lung dch

v UL xc nh c ch phn hi cho mi kt ni ng ln m bo b lp lch

UL c th tin on c. Hn na, vi knh con UL trc giao, khng c xuynnhiu t cell ngoi. Lp lch UL c th phn b ngun ti nguyn hiu qu hn v

tham s QoS tt hn.

S phn b ngun ti nguyn ng: MAC h tr s phn b ngun ti nguyn

i vi DL v UL trn mi khung. S phn b ngun ti nguyn c phn pht

trong bn tin MAP ti bt u mi khung. Do , s phn b ngun ti nguyn c

th c thay i t khungkhung theo cc iu kin v knh v lu lng. Hn

na, mt s lng ngun ti nguyn trong mi ln phn b c th thay i t 1 khe

n ton b khung. S phn b ngun ti nguyn ht tt v nhanh cho php QoS

tt hn cho lu lng s liu.

QoS oriented: B lp lch MAC x l truyn ti s liu trn mi kt ni-kt ni.

Mi kt ni c kt hp vi dch v s liu n vi mt tp hp cc tham s

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QoS. Vi kh nng ngun ti nguyn c phn b ng trong c DL v UL, b

lp lch c th h tr QoS cho c lu lng DL v UL. C th vi lp lch knh

ln-ngun ti nguyn ng ln c phn b hiu qu, QoS l tt hn.

Lp lch la chn tn: B lp lch c th hot ng trn cc kiu khc nhau ca

knh con. Knh con o tn s nh l hon v PUSC, ni m sng mang con trong

cc knh con c phn b gi ngu nhin trn bng tn, knh con c cht lng

tng t. Lp lch a dng tn s c th h tr QoS vi tnh ht tt v ngun ti

nguyn thi gian tn s mm do. Vi s hon v lin k nh hon v AMC, knh

con c th tri qua cc cng khc nhau. Lp lch la chn tn s c th phn

b cc thu bao di ng ti knh con mnh nht. Lp lch la chn tn s c th

tng cng kh nng h thng vi s tng ln va phi trong tiu CQI trong

UL.

2.3.2 H tr QoS

Vi tc ng truyn v tuyn cao, kh nng truyn ti bt i xng ng

ln/ng xung v mt c ch cp pht ti nguyn linh hot, WiMAX di ng hon ton

c th ap ng c cc yu cu QoS cho nhiu loi hnh dch v v ng dng d liu.

Trong lp MAC ca WiMAX di ng, QoS c cung cp qua lung dch v nh

c m t trong hnh bn di. y l lung gi c duy nht mt hng m c cung

cp vi mt tp cc tham s QoS c th. Trc khi cung cp mt loi dch v s liu cth, trm gc v u cui ngi s dng u tin thit lp mt kt ni logic mt hng

gia cc MAC. Sau , MAC kt hp cc gi qua giao din MAC vo mt lung dch v

c phn pht qua kt ni. Tham s QoS c kt hp vi lung dch v xc nh th

t truyn dn qua mi trng v tuyn. Do , QoS nh hng kt ni c th cung cp

iu khin chnh xc qua giao din v tuyn. Do giao din v tuyn thng l nt c chai,

QoS nh hng kt ni c th cho php hiu qu qua iu khin QoS end-to-end.

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Hnh 2.4: QoS h tr WiMAX di ng

Tham s lung dch v c th c qun l ng thng qua bn tin MAC tho

mn cc yu cu dch v ng. Lung dch v c da trn c ch QoS p dng cho c

DL v UL cung cp QoS ci thin trong c 2 hng. WiMAX di ng h tr mt

khong rng cc dch v s liu v ng dng vi yu cu QoS thay i. Chng c tng

kt trong bng sau:

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Bng 2.3: Cc dch v trong QoS

2.3.3 Qun l ngun

WiMAX di ng h tr 2 ch cho hot ng hiu qu ngun: ch sleep v ch

idle. Ch sleep l mt trng thi trong MS iu khin mt giai on tin tho

thun v s vng mt s phc v ca giao din v tuyn trm gc. Giai on ny c

c trng ho bi tnh khng kh dng ca MS, nh c quan st t s phc v ca trm

gc, lu lng DL hoc UL. Ch sleep cho php ti u cng sut MS v ti u s sdng ca ngun giao din v tuyn trm gc. Ch sleep cng cung cp s mm do

cho MS qut cc trm gc khc thu thp thng tin h tr handoff qua ch

sleep.

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Ch Idle cung cp c ch cho MS tr thnh kh dng tun hon cho bn tin

lu lng qung b m khng ng k ti mt trm gc c th no nh khi MS nm trong

mi trng lin kt v tuyn c chim gia bi nhiu trm gc. Ch idle mang li

li ch cho MS bi vic khng cn yu cu cho handoff v hot ng bnh thng khc v

li ch cho mng v trm gc bi s loi b giao din v tuyn v lu lng handoffmng t s khng hot ng ca MS trong khi vn cung cp mt phng php n gin

v kp thi cho cnh bo MS v pending lu lng DL.

2.3.4 Qun l di ng

C 3 phng php handoff c h tr trong chun 802.16e: handoff cng (hard)

(HHO-Hard Handoff), chuyn mch trm gc nhanh (FBSS- Fast Base Station Switching)

v handover chuyn giao phn tp v m (MDHO - Macro Diversity Handover).

Trong nhng phng php handoff trn, HHO l bt buc trong khi FBSS vMDHO l 2 ch tu chn. Din n WiMAX ang pht trin cc yu cu k thut cho

vic ti u handoff cng trong khung ca chun 802.16e. Nhng ci tin ny c pht

trin vi mc tiu l gi cho tr lp 2 ca handoff l b hn 50 ms.

Chuyn giao nhanh trong Wimax ch c th thc hin gia cc BS nm trong ci gi

l Diversity Set l tp hp cc BS hot ng trong cng tn s, c SINR ln MS

c th kt ni c v c bit l chng phi ng b. Trong Diversity Set ny th ch c

1 BS c gi l anchor (BS ch lc, hay cn gi l im kt ni, khp). S khc nhaugia MDHO v FBSS l ch: i vi FBSS, MS ch trao i thng tin d liu thng qua

BS anchor thi, cn MDHO th MS truyn lu lng d liu qua tt c cc BS nm trong

Diversity Set.

Khi FBSS c h tr, MS v BS duy tr mt danh sch cc BS m n lin quan n

FBSS vi MS. Tp hp ny c gi l tp hp tch cc. Trong FBSS, MS tip tc gim

st trm gc trong tp hp tch cc. Gia MS trong tp hp tch cc, mt BS anchor

c xc nh. Khi hot ng trong FBSS, MS ch truyn thng vi BS anchor cho bn

tin ng ln v ng xung bao gm qun l v kt ni lu lng. Chuyn dch t mtBS Anchor ti mt BS khc (v d chuyn mch BS) c thc hin m khng cn

bn tin bo hiu HO bt buc. Th tc cp nhp Anchor c thc hin bi di tn

hiu truyn thng ca BS phc v thng qua knh CQI. Chuyn giao FBSS bt u vi

mt quyt nh bi mt MS nhn v truyn s liu t mt BS anchor m c th thay

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i trong mt tp hp tch cc. MS thng bo NS c la chn v th tc cp nhp tp

hp tch cc. MS qut cc BS ln cn v la chn t nhng BS ny ra cc BS ph hp v

th tc cp nhp tp hp tch cc c thc hin bi BS v MS. MS tip tc gim st

di tn hiu ca BS m trong tp hp tch cc v la chn mt BS t mt tp hp tr

thnh BS anchor. MS thng bo BS anchor c la chn trn CQICH hoc MS btu bn tin yu cu HO. Mt yu cu quan trng ca FBSS l cc s liu c truyn

ng thi ti tt c cc thnh vin ca tp hp tch cc ca BS m cho php phc v MS.

Vi MS v BS m h tr MDHO, MS v BS duy tr mt tp tch cc cc BS m lin

quan n MDHO trong MS. Gia cc BS trong tp hp tch cc, BS anchor c xc

nh. Khi hot ng trong ch MDHO, MS truyn thng vi tt c BS trong tp hp

tch cc ca bn tin unicast ng ln v ng xung v lu lng. MDHO bt u khi

MS quyt nh truyn hoc nhn bn tin unicast v lu lng t nhiu BS trong cng mt

khong thi gian. Cho MDHO ng xung, 2 hoc nhiu BS cung cp truyn dn ng

b cho s liu ng xung MS m kt hp a dng c thc hin ti MS. Cho MDHO

ng ln, truyn dn t mt MS c nhn bi a BS trong khi s a dng la chn

trong thng tin nhn c c thc hin.

2.3.5 Bo mt

WiMAX di ng h tr tt nht cc c im an ninh bng cch s dng cc cng

ngh tt nht hin c hin nay. H tr s nht thc thit b/ ngi s dng, giao thc qun

l cha kho mm do, m ho lu lng mnh, bo v bn tin mt phng qun l v iu

khin, v cc ti u giao thc an ninh cho chuyn vng nhanh.

Cc kha cnh s dng cho cc c im an ninh l:

Giao thc qun l cha kho: giao thc qun l cha kho phin bn 2 (PKM v2)

l thnh phn c bn trong an ninh WiMAX di ng c xc nh trong 802.16e.

Giao thc ny qun l an ninh MAC s dng bn tin PMK-REQ/RSP, nht thc

PMK EAP, iu khin m ho lu lng, trao i cha kho handover v tt c bn

tin an ninh multicast/broadcast c da trn giao thc ny.

Nht thc thit b/ ngi s dng: WiMAX di ng h tr nht thc thit b v

ngi s dng s dng giao thc IETF EAP bng vic cung cp h tr

credentials c da trn SIM, hoc da trn USIM hoc chng nhn s hoc

da trn tn ngi s dng/mt khu. Tng ng vi phng php nht thc EAP-

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SIM, EAP-AKA, EAP-TLS, EAP-MSCHAPv2 c h tr thng qua giao thc

EAP.

M ho lu lng: AES-CCM l mt m ho c s dng bo v tt c s

liu ngi s dng qua giao din WiMAX MAC di ng. Cha kho c s

dng cho m ho c to ra t vic nht thc EAP.

Bo v bn tin iu khin: s liu iu khin c bo v bng vic s dng AES

hoc s dng CMAC hoc s HMAC da trn MD5.

H tr chuyn vng nhanh: Mt s bt tay 3 bc c h tr bi WiMAX

di ng ti u c ch nht thc li cho h tr chuyn vng nhanh. C ch ny

cng hu ch trong vic chng li vic tn cng gia chng bi con ngi

hacker.

2.3.6 Truy nhp knh truyn

Khi mt MS m my n s tin hnh cc bc sau kt ni vi trm BS nh c

m t hnh di y.

Thc hin qu trnh tm kim v ng b ha vi cc BS m n thu c sng

radio. thc hin c iu ny, cc MS s tin hnh scan cc tn s DL ( bit

trc), lng nghe cc DL preamble pht ra t cc BS v ng b ha da vo cc

thng ip iu khin.

Tip theo MS nhn bit cc thng s uplink bng cch lng nghe cc UL-MAP.

MS thc hin qu trnh ranging. Ci ny ging nh power control trong mng

thng tin di ng t bo.

MS tha thun v vic thu nhn bng thng vi BS cng nh cc thng tin v

profile.

MS thc hin qu trnh nhn thc, trao i kha v tin hnh ng k truy nhp

vo mng. Kt ni IP c thit lp Lung dch v c th bt u c trao i.

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Hnh 2.5: Cc bc kt ni vi trm BS

2.4 Cc c im ci tin ca WiMAX di ng

2.4.1 Cng ngh anten thng minh

2.4.1.1 MIMO

K thut MIMO trong lnh vc truyn thng l k thut s dng nhiu anten pht v

nhiu anten thu truyn d liu. MIMO technique tn dng s phn cc (khng gian,

thi gian, m ha ...) nhm nng cao cht lng tn hiu, tc d liu. K thut MIMO

ngy nay ang c ng dng rt rng ri: MIMO-Wifi, MIMO-UMTS...nh tnh ti u

trong vic s dng hiu qu bng thng, tc d d liu cao, robust vi knh truyn fading.

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Hnh 2.6 : K thut MIMO

K thut MIMO tng i a dng v phc tp. Trong WiMAX, ngi ta s dng

m ha thi gian khng gian nhm lm gim qu d tr yu cu v trnh nhiu. i vi

phn tp pht, rt nhiu cc phng php c kt hp nhm ci thin kh nng ca h

thng.

2.4.1.2 Cng ngh Anten thng minh

Cng ngh an ten thng minh in hnh lin quan n vc t phc hoc hot ng ma

trn ca tn hiu bi nhiu an ten. OFDMA cho php cc hot ng an ten thng minh

c thc hin trn cc sng mang con vc t phng. S cn bng phc khng c yu

cu b cho fading theo tn s. Do , OFDMA l ph hp tt vi s h tr cng ngh

an ten thng minh. Thc t, MIMO-OFDM/OFDMA c xem nh l mt nn mng cho

h thng truyn thng bng rng th h tip theo. WiMAX di ng h tr mt khong

rng cc cng ngh an ten thng minh tng cng kh nng thc hin ca h thng.

Cng ngh an ten thng minh h tr bao gm:

Beamforming: vi beamforming, h thng s dng nhiu n ten truyn tn hiu

vi mc ch ci thin vng ph v kh nng ca h thng.

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M ho thi gian-khng gian: truyn da dng nh l m ho alamuoti, c h

tr cung cp s a dng v khng gian v gim lch fade.

Ghp knh khng gian: ghp knh khng gian c h tr tn dng u im

ca tc cao v tng thng lng. Vi ghp knh khng gian, nhiu lung s

c truyn qua nhiu an ten. Nu b thu cng c nhiu an ten, n c th tch

nhiu lung khc nhau thu c thng lng cao sn so vi h thng ch c mt

an ten. Vi 2*2 MIMO, SM tng tc s liu nh ln 2 ln bng cch truyn 2

lung s liu. Trong UL, mi ngi s dng ch c duy nht mt anten truyn dn,

2 ngi s dng c th truyn kt hp trong cng 1 khe nu 2 lung c ghp

knh theo thi gian t 2 an ten ca cng mt ngi s dng. iu ny c gi l

UL kt hp vi SM.

Cc c im c h tr trong profile WiMAX di ng c lit k trong bng sau:Bng 2.4: Cc ty chn ca Anten cao cp

WiMAX di ng h tr chuyn mch thch ng gia cc tu chn ti u li ch

ca cng ngh an ten thng minh trong cc iu kin knh khc nhau. V d, SM ci thin

thng lng nh. Tuy nhin, khi iu kin knh km, tc li gi c th cao v do

vng bao ph i vi PER mc tiu c th l gii hn. Mt khc, STC cung cp mt vng

ph ln khng quan tm n iu kin knh nhng li khng ci thin c tc s liu

nh. WiMAX di ng h tr chuyn mch thch ng gia a ch MIMO ti a ho

s hiu qu bng tn m khng gim i vng bao ph. Hnh 11, ch ra kin trc cho vic

h tr cc c im an ten thng minh. Bng sau cung cp tng kt v tc s liu nhv mt l thuyt cho cc t s DL/UL vi gi s bng tn knh 10 MHz, di khung

5ms vi 44 k t s liu OFDM (trn 48 k hiu OFDM) v knh con ho PUSC. Vi

2*2 MIMO, ngi s dng DL tc s liu nh ca sector c gp i. Tc s liu

nh DL ti a l 63.36 Mbps khi tt c k hiu s liu c gp i trong khi tc s

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liu nh ngi s dng l khng i. Tc s liu nh ngi s dng UL v tc s

liu nh sector l 14.11Mbps v 28.22 Mbps tng ng khi tt c k t s liu l UL.

Bng cch p dng cc t s DL/UL khc nhau, bng tn c th c iu chnh gia DL

v UL m bo cho cc mu lu lng khc nhau. Ch l trong trng hp m ton

DL hoc ton UL l him c s dng. Profile WiMAX h tr t s DL/UL thay i t3:1 ti 1:1 tho mn cc profile mu lu lng khc nhau.

Bng 2.5: Cc tc d liu cho cc cu hnh SIMO/MIMO

Hnh 2.7: Chuyn mch thch ng cho anten thng minh

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2.4.2 S dng li tn s phn on

WiMAX di ng h tr vic s dng tn s, ngha l tt c cc cell/sector hot ng

cng mt knh tn s ti a hiu qu bng tn. Tuy nhin, do xuyn nhiu knh ln

(CCI) trong vic trin khai mt tn s c s dng li, ngi s dng ti bin ca cc

cell c th chu s suy gim v cht lng kt ni. Vi WiMAX di ng, ngi s dng

c th hot ng trn cc knh con, m ch chim mt phn nh trong ton th bng tn

knh, vn xuyn nhiu bin ca cell c th c gii quyt d dng bng vic s dng

knh vi cu hnh ph hp.

Trong WiMAX di ng, s dng knh con mm do bng cch phn mnh knh con

v vng hon v. Mt on l mt phn vng ca mt knh con OFDMA kh dng (mt

on c th bao gm tt c cc knh con). Mt on c s dng cho vic trin khai mt

MAC n.Vng hon v l mt s cc k hiu OFDMA lin k trong DL hoc trong UL m s

dng cng hon v. Khung con DL hoc UL c th cha nhiu hn mt vng hon v nh

c ch ra trong hnh sau:

Hnh 2.8: Cu trc khung a min

Mu s dng li knh con c th c cu hnh ngi s dng gn trm gc hot

ng ti vng vi tt c knh con kh dng. Trong khi i vi ngi s dng bin, mi

cell hoc sector hot ng trong vng vi mt phn ca tt c cc knh. Trong hnh trn

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F1, F2, F3 i din cc tp hp knh con trong cng mt knh tn s. Vi cu hnh ny,

mt s dng li tn s c duy tr cho ngi s dng trung tm ti u ho hiu

qu ca ph v s dng li tn s mt phn c thc hin cho ngi s dng bin

m bo cht lng kt ni ngi s dng bin v thng lng. K hoch s dng li

knh con c th c ti u t ng qua cc sector hoc cell da trn ti mng v iukin can nhiu trn mt khung. Do , tt c cc cell hoc sector c th hot ng cng

mt knh tn s m khng cn k hoch tn s.

Hnh 2.9: S dng li tn s

2.4.3 Dch v Multicast v Broadcast (MBS)

MBS c h tr bi WiMAX di ng kt hp cc c im tt nht ca DVB-H,

Media FLO v 3GPP E-UTRA v tho mn cc yu cu sau:

Tc s liu cao v vng ph s dng mng tn s n (SFN Single Frequency

Network).

S phn b mm do cc ngun ti nguyn v tuyn

Tiu th cng sut MS thp

H tr casting-data, lung video v audio.

Thi gian chuyn mch knh thp

Profile WiMAX phin bn 1 xc nh mt tp hp MBS. Dch v MBS c th c

h tr bi hoc xy dng mt vng MBS ring trong khung DL cng vi dch v unicast

(MBS) hoc mt khung tng th c th c dnh cho MBS (ch c trong DL) cho dch

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v broadcast standalone. Hnh 2.9 ch ra vic xy dng vng khi c vic trn gia dch v

broadcast v unicast c h tr. Vng MBS h tr ch nhiu BS MBS s dng mng

tn s n (SFN) v di mm do ca vng MBS cho php gn scalable cc ngun ti

nguyn v tuyn ti lu lng MBS. N c rng nhiu vng MBS c th cng

mm do. C mt vng MBS trn vng MBS. MS c th truy nhp DL MAP ti vic xcnhn ban u vng MBS v phn b MBS MAP trong mi vng. Sau MS c th c

ln lc MBS MAP m khng tham chiu DL MAP tr khi s ng b ti MBS MAP b

mt. MBS MAP IE ch ra cu hnh PHY vng MBS v xc nh s phn b ca mi vng

MBS qua tham s offset k t OFDMA. MBS MAP c phn b ti knh con s mt

ca k t OFDM s mt ca vng MBS. a BS MBS khng yu cu MS c ng k

ti bt c trm gc no. MBS c th truy cp khi MS trong ch Idle cho php cng

sut tiu th thp. mm do ca WiMAX di ng h tr MBS tch hp v dch v

unicast cho php mt khong rng hn cc ng dng.

Hnh 2.10: H tr MBS nhng vi nhng vng WiMAX-MBS di ng

2.5 Cc vn v ph ca WIMAX di ng

thu c li nhun tt nht t h thng WiMAX, cc n nh ph vi lu lng

ln l ng quan tm nht. iu ny cho php cc h thng c trin khai theo kiu

TDD vi di thng knh ln, s dng li tn s linh hot v s km hiu qu ca ph vi

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tn s nh chp nhn cng tn ti m bo cho cc nh cung cp dch v c th hot

ng cng nhau. Phm vi hot ng khc ca din n WiMAX l ang cng tc vi cc

t chc tiu chun ton cu phn cp ph ca di tn s thp (


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Kin trc mng end-end WiMAX di ng c da trn nn tng IP, tt c l mch

gi v khng tha k t mch thoi. N mang n cc u im v vic gim gi thnh

tng th qua vng i pht trin mng WiMAX. S dng mng ton IP ngha l li mng

chung c th c s dng, m khng cn thit duy tr c mng li knh v mng li gi.

Mt li ch na ca mng ton IP l n thay th mng vi kh nng ca b x l v thitb tnh ton, c gi l lut Moore. Cc ci tin x l my tnh xy ra nhanh hn ci

tin trong thit b vin thng bi v phn cng khng b gii hn bi vng trn thit b

vin thng. Kt qu cui cng l mt mng c thc hin lin tc vi hiu sut lm

vic cao hn em li thun li cho nh cung cp th 3 pht trin t truyn thng

internet. Kt qu ny em li gi thnh thp hn, scalability cao v s trin khai nhanh do

chc nng mng ca cc dch v da trn trn phn mm l chnh.

trin khai h thng thng mi hot ng mt cch thnh cng, h thng phi

c h tr cc ch tiu giao din v tuyn 802.16 (PHY/MAC). Phn chnh trong chng

l s cn thit h tr mt tp hp li cc chc nng lin mng nh mt phn ca kin

trc h thng WiMAX end-end tng th. Trc khi a ra chi tit v kin trc, chng ta

u tin n vi nguyn l c bn c hng dn pht trin cho kin trc

WiMAX.

Kin trc c da trn khung chuyn mch gi, bao gm cc th tc c bn c

da trn IEEE 802.16 v cc b xung, ph hp vi IETF RFC v chun Ethernet.

Kin trc cho php tch kin trc truy nhp (v cc cu hnh c h tr) t kt ni

dch v IP. Phn t mng ca h thng kt ni phi tun theo chun v tuyn IEEE

802.16

Kin trc cho php iu chnh linh hot cung cp mt khong rng cc tu chn

trin khai nh l:

Mng WiMAX kch thc nh n kch thc ln ( bao ph v tuyn tha tht

ti dy c).

Mi trng truyn sng v tuyn nng thn, thnh th v min ni.

Giy php cung cp cc bng tn

Cu hnh nhnh, phng, li v hn hp.

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Cho php a dng cc m hnh s dng cho c nh, lu ng, portable, di ng.

2.6.1 H tr cc dch v v ng dng

Kin trc end-end bao gm cc h tr cho:

Thoi, dch v a phng tin v cc dch v bt buc khc nh l dch v khncp.

C kh nng truy cp ti nhiu nh cung cp dch v ng dng c lp (ASP)

Truyn thng thoi di ng s dng VoIP

H tr giao din vi a dng interworking v cc media gateways cho php phn

pht cc dch v incumbent/legacy c dch qua IP (v d, SMS qua IP, MMS,

WAP) ti mng truy nhp WiMAX.

H tr s phn pht dch v IP multicast v broadcast qua mng truy nhp

WiMAX.

2.6.2 Lin mng v chuyn vng

Lin mng v chuyn vng l thnh phn quan trng ca kin trc mng end-end vi

s h tr cho mt s lng cc kch bn dc trin khai. C th chng s h tr cho cc

trng hp sau:

Lin mng vi cc mng khng dy tn ti nh 3GPP, 3GPP2 hay DSL, MSOvi giao din lin mng da trn tiu chun IETF ph hp vi cc giao thc

Roaming ton cu thng qua mng WiMAX, bao gm cc tnh nng nhn thc v

tnh cc

Nhiu nh dng kh nng nhn thc ngi dng nh l tn/ mt khu, chng ch

s, m dun xc nhn thu bao (SIM), SIM universal, v m un xc nhn ngi s

dng c th di chuyn c (RUIM).

Din n WiMAX ang xc nh mt m hnh tham chiu mng WiMAX (NRM)i din cho logic ca kin trc mng. NRM xc nhn cc thc th chc nng v im

tham chiu qua m kh nng lien hot ng t c gia cc thc th. Kin trc c

pht trin vi mc tiu l cung cp s h tr duy nht cc chc nng c cn thit vi

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mt khong m hnh trin khai mng v kch bn s dng (mt khong t c nh-lu

ng-portable-di ng n gin v n di ng hon ton).

Hnh 2.11: M hnh tham chiu mng WIMAX

Hnh v trn m t NRM, bao gm cc thc th logic sau: MS, ASN v CSN v

im tham chiu xc nh r rng cho lin kt ni ca cc thc th logic. Hnh m t cc

im tham chiu chnh R1-R5. Mi thc th, MS, ASN, v CSN i din mt nhm cc

thc th chc nng. Mi mt chc nng c th c nhn ra trong mt thit b vt l n

hoc c th c phn b qua cc thit b vt l. Nhm v phn b cc chc nng vo

thit b vt l trong thc th chc nng (nh l ASN) l mt s tu chn; mt nh sn

xut c th chn bt c vic thc thi chc nng vt l no, hoc ring r hoc kt hp,min l s thc thi t c yu cu lin hot ng.

Mc ch ca NRM l phi cho php cc tu chn thc thi cho mt thc th chc

nng c cho v t c s lin hot ng gia cc thc th chc nng khc nhau. Lin

hot ng c da trn s xc nh v giao thc truyn thng v i x mt phng s

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liu gia cc thc th chc nng t c cc chc nng end-end tng th, v d, An

ninh v qun l di ng. Do , thc th chc nng trn mt mt ca im tham chiu i

din cho mt tp hp cc im cui mt phng mang (bearer).

ASN xc nh mt gii hn lo gic v i din mt cch tin cy m t mt tp hp

cc thc th chc nng v tng ng vi lung bn tin c kt hp vi cc dch v truy

nhp. ASN trnh by mt cn cho vic lin hot ng vi client WiMAX, chc nng dch

v kt ni WiMAX v tch hp cc chc nng emboied bi cc nh cung cp khc nhau.

nh x cc thc th chc nng ti thc th logic trong ASN nh c m t trong NRM

c th c thc hin theo cc cch khc nhau. Din n WiMAX a ra cc ch tiu k

thut mng m bo c a dng cc sn phm ca cc nh sn xut c th lin hot

ng v c ph hp cc yu cu trin khai a dng.

Mng dch vu kt ni (CSN) c xc nh nh l mt tp hp cc chc nng mngm cung cp cc dch v kt ni IP ti cc thu bao WiMAX. Mt CSN c th bao gm

cc phn t mng nh l router, AAA proxy/Server, c s d liu ngi s dng v thit

b gateway lin hot ng. Mt CSN c th c trin khai nh mt phn ca nh cung

cp dch v mng WiMAX Greenfield (NSP) hoc mt phn NSP WiMAX incumbent.

Hnh di y cung cp mt quan im c bn hn na v rt nhiu thc th trong

nhm chc nng ASN v CSN.

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Hnh 2.12: Cu trc mng WiMAX trn nn IP

Cc ch tiu k thut mng cho h thng WiMAX c da trn vi nguyn l

kin trc mng c bn, bao gm cc nguyn l c lit k di y.

Cung cp cc vn logc gia th tc v a ch IP, nh tuyn v th tc qun l

kt ni v giao thc cho php s dng cc kin trc truy nhp c bn trong mt

chui kch bn trin khai interworking v standalone

H tr cho vic chia s ASN ca mt nh cung cp truy nhp mng (NAP) vi a

nh NSP

H tr dch v cung cp NSP n qua ASN-c qun l bi mt hay nhiu NAP

H tr cho vic khm ph v la chn NSP c th truy nhp c bi mt MS

hoc SS

H tr NAP m trin khai mt hay nhiu cu hnh ASN

H tr truy nhp ti cc dch v nh khai thc incumbent qua chc nng

internetworking

Cc ch tiu k thut cho im tham chiu c xc nh r rng gia cc nhm

khc nhau ca thc th chc nng mng (trong mt ASN, gia ASN, gia mt

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ASN v mt CSN v gia CSN), v c th gia mt MS, ASN, v CSN cho

php lin hot ng a nh sn xut.

H tr s pht trin gia cc m hnh s dng khc nhau ti cc gi s k thut c

th v bt buc

Cho php nhiu nh sn xut khc nhau da trn s kt hp khc nhau cc thc th

chc nng trn thc th mng lp vt l, min l s thc thi ny tun theo cc giao

thc thng thng v cc th tc qua im tham chiu ng dng c th, nh c

xc nh trong cc ch tiu k thut mng

H tr kch bn thng thng nht ca mt nh cung cp dch v trin khai mt

ASN cng vi mt tp hp gii hn cc chc nng CSN, m cc nh khai thc

c th cung cp cc dch v truy cp internet c bn m khng cn xem xt n

roaming v interworking.

Kin trc WiMAX cng cho php c IP v dch v Ethernet, trong mng tun theo

chun IP di ng. S mm do v lin hot ng c h tr bi mng WiMAX cung cp

cho cc nh khai thc mng vi gi thnh thp ca a nh sn xut ca mng WiMAX

thm chi vi s trin khai gia mng ASN tp trung v phn b trong mng.

2.6.3 Bo mt

Kin trc mng WiMAX end-end c da trn an ninh mng m l agnostic ti

cc kiu nh khai thc v cu hnh ASN v p dng qua m hnh trin khai

internetworking v Greenfield v cc kch bn h tr. Trong thc t n c cc h tr:

Nht thc thit b mutual mnh gia mt MS v mng WiMAX, c da trn

khung security IEEE 802.16

Tt c c ch nht thc c trin khai chung v nht thc ti nh v kch bn

mng nh khai thc c da trn khung nht thc m rng v chc chn

Tch hp s liu, bo v replay

S dng c ch an ninh cho MS bt u/kt thc nh l mng ring o (VPN), c

ch qun l a ch IP secure chun gia MS/SS v nh v NSP visited.

2.6.4 Tnh di ng v chuyn giao

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Kin trc mng WiMAX end-end c kh nng m rng h tr tnh di ng v

handover. N s:

Chuyn giao cng cng ngh v chuyn giao gia cc cng ngh (nh:WIFI,

3GPP, 3GPP2, DSL hoc MSO) nu nh MS c h tr hot ng nhiu ch

H tr IPv4 hoc IPv6 c da trn qun l tnh di ng. Trong khung ny, v

nh c th, kin trc s m bo MS vi a a ch IP v kt ni IPv4 v IPv6

ng thi

H tr chuyn vng gia cc NSP

S dng c ch h tr chuyn vng seamless ti tc di chuyn ca phng

tin - tho mn gii hn ngn dch v. Mt vi kh nng khc c h tr tnh di

ng bao gm h tr:

Cu hnh a ch mng tnh v ng

S gn ng ca Home Agent trong mng nh cung cp dch v nh l mt

dng ca vic ti u tuyn, cng nh mng IP nh nh mt dng ca vic

cn bng ti.

n nh ng ca Home Agent da trn cc c ch.

2.6.5 Kh nng m rng, vng bao ph v la chn nh khai thc.

Kin trc mng WiMAX end-end c kh nng m rng linh ng v mm do. C

th, n s:

Cho php ngi s dng la chn hoc t ng hoc bng tay t NAP v NSP kh

dng.

Cho php thit k ASN v CSN m c th thay i quy m d dng-theo cc kha

cnh bao ph, khong hoc kh nng

m bo mt khong rng cc cu hnh ASN- bao gm hub v spoke, nhnh, linkt ni multi-hop

Tho mn mt khong rng cc lin kt backhaul, c v tuyn v hu tuyn vi s

k tha khc nhau v cc c im thng lng

H tr trin khai c s h tng ngy 1 phc tp

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H tr s dng cc dc v IP m do tng s thu bao hot ng v dch v IP

trn ngi s dng

H tr s tch hp cc trm gc ca vng ph a dng v kh nng-v d, trm gc

macro, mirco, pico v h tr tch v tch hp cc chc nng ASN trong trin khai

mng ASN cho php s dng s cn bng ti cho vic s dng hiu qu ph

v tuyn v cc ngun ti nguyn mng.

Cc c im khc gn lin vi nng lc ca h thng v kh nng qun l ca kin

trc mng WiMAX bao gm: h tr mt khong rng cc gim st client online v

offline, v s qun l c da trn chun cng nghip IP, trin khai rng, m, b) kh

nng dch v qua mi trng v tuyn (OTA) fho gim st u cui MS v nng cp phn

mm.

2.6.6 Kh nng lin hot ng ca a nh sn xut

Mt kha cnh quan trng khc ca kin trc mng WiMAX l h tr lin hot ng

gia cc thit b t nhiu nh sn xut khc nhau trong mt ASN v qua cc ASN khc

nhau. Nhng lin hot ng nh vy s bao gm cc lin hot ng gia: BS v thit b

backhaul trong mt mng ASN, v nhiu phn t ASN (c th t cc nh sn xut khc

nhau) v CSN, vi ti thiu hoc khng c s suy gim trong chc nng hoc kh nng

ca ASN.

Chun IEEE 802.16 xc nh a lp con hi t. Khung kin trc mng WiMAX h

tr mt khong cc kiu CS bao gm: ethenet CS, IPv4 CS v IPv6 CS.

2.6.7 Cht lng dch v

Kin trc mng WiMAX c mt kh nng h tr c ch QoS. C th, n cho php

h tr mm do vic s dng ng thi mt tp hp a dng cc dch v IP. Kin trc h

tr:

Tp hp QoS khc nhau (trn ngi s dng/u cui) hoc fine-grained (tng

lung dch v trn ngi s dng/terminal)

iu khin phn quyn

Qun l bng thng

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Thc thi cc chnh sch nh c quy nh bi cc nh khai thc cho cc SLA da

trn QoS (bao gm bt buc cho mi user v nhm ngi s dng cng nh cc

nhn t khc nh: nh v, thi gian

Cc ch tiu k thut mng WiMAX mm do cho php thc thi cc cu hnh mng

dch v truy nhp khc nhau tn l profiles ASN, bao gm c kin trc tp trung cng nh

phn b. Hn na, din n WiMAX ang pht trin mt khung lin hot ng trong

Intra-ASN v lin ASN hot ng vi cc nh sn xut khc nhau c m bo.

CHNG 3: NG DNG TRIN KHAI WiMAX DI NG TRN

MNG NI HT TI VIT NAM

3.1 Tng quan

u nm 2006, B Bu chnh vin thng cp php th nghim trong 1 nm dch

v WiMax c nh cho 4 doanh nghip gm: Viettel, VTC, VDC v FPT Telecom. K

hoch l thng 4/2007, sau khi c bo co t nhng n v ny, B s la chn 3 nh

cung cp chnh thc mng bng rng khng dy. Tuy nhin, vic cp php WiMax cnh vn cha c thc hin v nhiu l do. Cc doanh nghip khng nh kt qu th

nghim rt kh quan. Trong khi , pha B nhn nh kh nng thng mi ca cng

ngh ny th trng Vit Nam ph thuc phn ln vo gi c thit b u cui. Thi

im kt thc th nghim (nm 2007), gi thit b cn cao v khng phong ph.

Trong nm 2007, B Bu Chnh Vin Thng cp php cung cp dch v Wimax di

ng. Wimax di ng mi l trin vng ln nht ca Wimax. Vi cng ngh ny, ngi

dng u cui c th c s dng Internet tc cao ln n 1Mbps, ti bt k ni notrong vng ph sng bn knh rng nhiu km. Thit b u cui ca dch v Wimax di

ng c th l cc card PCMCIA, USB, hoc c tch hp sn vo trong con chip

my tnh (kiu nh cng ngh Centrino ca Intel).

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Bn doanh nghip vin thng Vit Nam c B TT-TT cp php cung cp dch v

th nghim cng ngh Wimax di ng l: VNPT, Viettel, EVN Telecom v FPT

Telecom.

Thi hn c th nghim dch v trong vng 01 nm vi quy m khng qu 1000

thu bao. C th, Tp on VNPT c th nghim bng tn 2.5 GHz ti H Ni,

TP.HCM v Nng. Viettel s dng bng tn 2.3-2.4 GHz ti H Ni v Thi Nguyn.

EVN Telecom th nghim ti bng tn 2.3-2.4 GHz khu vc H Ni v ng Nai. FPT

Telecom c th nghim cng ngh Wimax di ng bng tn 2.3-2.4 GHz ti H Ni

v Hi Phng.

Cc doanh nghip s c php th nghim ch yu cc loi hnh dch v vin

thng bng rng. Wimax di ng ch yu cung cp dch v cho cc sn phm di ng

nh: my tnh xch tay, in thoi di ng, PDA, thit b khng dy Vi Wimax ding, ngi tiu dng c th truy cp Internet khng dy tc cao ln ti 1Mbps trong

vng ph sng bn knh rng nhiu km.

3.2 Trin khai WIMAX di ng ca cng ty Vin Thng H Ni (HNPT)

3.2.1 Mc tiu trin khai

Hin nay HNPT v ang trin khai cc dch v truy cp Internet bng rng qua

cc h thng cp ng, cp quang nh: ADSL, Mega Wan, TSL v tin ti l mng

MAN. ng trc yu cu ca th trng cn phi cung cp dch v truy cp Internetbng rng linh hot hn trin khai d dng, p ng nhanh chng v c kh nng tip

cn c n cc khu vc, cc ta nh m mng ca HNPT cha trin khai c. p

ng cc yu cu nu trn, trong giai on ti HNPT cn phi trin khai mt h thng truy

cp v tuyn bng rng (Broadband Wireless Access) h tr v b sung cho cc h

thng truy nhp bng rng hin c.

3.2.1.1 Yu cu v dch v cho h thng truy nhp v tuyn bng rng

Sn sng cung cp ngay cc dch v: truy nhp Internet tc cao cho cc thu baoc nh v di ng (di chuyn vi tc < 40 km/h), lm backhaul cho cc im

truy nhp WiFi hotspots.

H tr trin khai mt s dch v trong thi gian ti: VoIP, kt ni E1, ng dng

Video v Multimedia...

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3.2.1.2 i tng khch hng ca h thng truy nhp v tuyn bng rng

Khch hng mt s khu th mi v mt s ta nh cao tng m mng cp do

cc doanh nghip mi trin khai.

Cc khu vc ngoi thnh kh trin khai mang cp hoc chi ph cho u t mngcp qu ln.

Cc khch hng s dng dch v di ng bng rng

3.2.2 Qui m trin khai WIMAX di ng ti H Ni

Trn c s cc khu vc cha c mng cp v trn c s h tng rt tt c ca

VNPT, Vin Thng H ni xut trin khai dch v truy nhp Internet bng rng qua h

thng WiMAX di ng vi mt s tiu ch nh sau :

Ph sng cho ton b cc khu vc VIETTEL trin khai mng cp (khu M nh 1,

Trung Ho - Nhn Chnh, khu Yn ho, khu Nam Trung Yn, khu ti nh c Cu

Giy...).

Qui m h thng mc ph hp nhm thm d th trng cng nh c thi

gian nh gi v kim chng cng ngh WiMAX.

H thng sn sng kh nng nng cp ln cc Version mi ca cng ngh WiMAX

di ng v m rng dung lng khi c yu cu.

Vi mc tiu c n nh sm tn s di 2.5 GHz.

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Hnh 3.1: S cc khu vc trin khai WiMAX di ng

3.2.3 Phi hp th nghim trin khai Wimax gia Motorola v HNPT

Ni dung

Bn xut Phi hp Th nghim Cng ngh (PTC) do Motorola xy dng dnh

ring cho HNPT v vic cung cp v cho mn mt mng theo chun mng 802.16e ti

gii tn 2.5GHz c cp php. Gii php ny khng ch l la chn thay th i viknh thu ring hay cp quang truyn thng m cn m rng vng ph sng v dch v

bng rng n cc th trng cha c phc v tt v cha c phc v. Motorola

xy dng k hoch th nghim ny da trn vic tm hiu v cc mc tiu ca HNPT

nhm cung cp dch v bng rng v tuyn ra th trng trn a bn H Ni. im duy

nht ch c trong xut ca Motorola l cung cp trn gi theo hnh thc cha kha trao

tay bao gm Mng truy nhp V tuyn/ Mng truy nhp dch v (gm cc im truy nhp

AP, thit b u cui thu bao SM v CPE) v Mng dch v li (AAA, NMS, BRAS,

SSGW, IMS,vv) cng vi h tr cc ng dng cho ngi s dng nh: im truy cp

Internet, VoIP v Video. Gii php ny c tng sc mnh vi cc dch v chuyn

nghip ca Motorola nh : quy hoch tn s v mng, Tch hp h thng, o to khch

hng v Qun l trin khai.

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Mng th nghim c thit k nhm gip HNPT thc hin cc cng vic sau :

Xc nh hiu nng h thng

Xc thc tnh kh quan i vi cng ngh WiMAX di ng.

C c nhng hiu bit thu o v sao cng ngh WiMAX di ng h tr v

thc y ton din vic kinh doanh bng rng v tuyn ca HNPT

Cng c nn tng ca vic kinh doanh bng rng v tuyn s dng cng ngh

WiMAX di ng.

3.2.3.1 M t ULAP Wi4 ca Motorola

M t cu hnh ULAP: ULAP c cu hnh sector ha 90 vi mt b phn tch

hp RF

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Hnh 3.2: Cu hnh sn phm Ultra Light


60/85


Hnh 3.3 : Cu hnh sn phm ULAP

Hnh trn th hin vic lp t trm c bn cho ULAP v module qun l nhm.

ULAP v module qun l nhm c thit k lp t bn ngoi nh trm / ta nh

nhm trin khai zero footprint vi chi ph thp.

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Hnh 3.4: Framework qun l cc phn t ULAP

Hnh 3.5: Cu hnh cell in hnh (4 sector)

- 61 -


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Motorola cng cung cp module thu bao ULAP (SM) trin khai ngoi tri. Li

th ca module thu bao (SM) treo rt thun li cho vic to ra mc tn hiu ln hn cho

php vng ph sng rng v tc truyn d liu cao hn so vi vic trin khai trong

nh. SM ngoi tri cng c cng RJ45 n ti my tnh khch hng hoc mng my tnh.

- 62 -

Hnh 3.6: Module thu bao ngoi tri


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Hnh v di y ch ra cu hnh cho h thng trm gc Motorola MOTOWi4

ULAP v v bng m t cc tnh nng ca n:

- 63 -

Hnh 3.7 : Cu hnh a sector ca ULAP


64/85


Bng 3.1: Tng hp nhng c tnh k thut chnh ca ULAP

Kt qu m phng s dng b thu bao ngoi tri 3500 da trn cc thng s sau:

Bng tn 2.5GHz, chia Uplink/Downlink l 75% / 25%

Mc tiu dch v cell edge: 1.024 Mbps Downlink, Uplink 128kps (ph sng

90%)

cao ngten ULAP tnh t mt t: 30m, cao b thu bao ngoi tri ULAP

tnh t mt t : 7m.

Kiu b m lu lng d liu ton phn (Video/ Audio Streaming).

Da vo tc kt ni trung bnh ca 1 user qua 1 sector. rng bng thng ca knh 7MHz c h tr theo vic nng cp phn mm

cho h thng

Throughput ln nht ca mi sector >> dung lng trung bnh.

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- 65 -

iu khin truyn ti in p t ng (ln ti-20 dB)Qun l cng sut

AP:


66/85


- 66 -

DC ni tBo v ngun sng

Yu cu ng dng bt buc

Chng hn: ETSI EN302 021, 753; RoHS/WEEEMy trit sng ty chn (nu cn)Regulatory Compliance

99.99+%Sn c

IEEE 802.3 (10/100 BT Ethernet)Giao din dy

Ethernet (Cng sut qua Ethernet) qua Cat-5CMM ti im truy nhpcp

DES v AES (Ty chn), FIPS Certified (cho AES)Bo mt

2 mcQoS

RSAAuthentication

Lp 2 IEEE 802.1p, IPv4 Diffserv (DSCP)Phn loi lu lng

802.1QH tr VLAN

IPv4, TCP, UDP, PPP, SNMPGiao thc h tr

Bng 3.3: c tnh k thut v tuyn ca ULAP (tip)


67/85


- 67 -

DC ni tBo v ngun sng

Tilt Mounting Kit for 2 to 4.5 ng knh ccCc gn vo phn cng

ETSI EN 302 085 CS3Phn cc cho ti thiu

ETSI EN 302 085 CS3Minimum Front-to-BackIsolation

ETSI EN 302 085 CS3Gc phng viSidelobes

50 OhmTr khng u vo

45 Win p vo ti a

Xung -25oElevation Null Fill

0oGc ngng in caanten

7oMt chiu rng chm3 dB

4 sector | 360oGc phng vi rngchm 3 dB

18 dBiMc thu ti thiu

DcPhn cc ha

Bng 3.4: c tnh k thut anten ca ULAP


68/85


- 68 -

42 dBm EIRP = 25 dBm + 17 dBi (30o internalant.)Actual EIRP thay i theo chc nng ca quynh v yu cu mt n quang ph (c th tngquc gia)

Cng sut u ra ti a(PA and Antenna)

-40C to 55CNhit vn hnh

2.5 kgTrng lng

254 x 355 x 76 mmKch thc vt l

Cu hnh t xa/ phn mm c th nng cp cCu hnh

OFDM PHY v trc chun MAC(802.16e vi nng cp phn mm)

Kin trc

OFDM / TDD (OFDMA vi nng cp phn

mm)Giao din kh

3.5 MHz (7MHz vi nng cp phn mm)Bng thng ca knh

2.300 2.500 GHzDi tn

C nh v nomadicng dng

Bng 3.5: Cc thng s k thut Module v Anten thu bao


69/85


- 69 -

Yu cu ng dng bt bucChng hn: ETSI EN302 021,753; RoHS/WEEE.Cc my trit sng ty chn (nu cn)

p ng yu cu

Xy dng server DHCP cho ngi dng LANDHCP client cho WANDHCP

IPSec, PPTP & L2TP Pass-ThroughVPN

NAT, DMZ HostHm NAT

Xy dng trong tng la h tr ngi s dng253 LAN

Tng la

IEEE 802.1QH tr VLAN

IEEE 802.3 (10/100 BT Ethernet)Giao din LAN

DES and AES (optional), FIPS Certified (forAES)

Bo mt

2 levelsQOS

IPv4, TCP, UDP, PPP, SNMPH tr giao thc

H thng iu khin cng sut truyn t ng (lnti 20 dB)Qun l cng sut

55 VDC / 45 Wattsin p tiu dng

90 to 264 VAC/ 50-60 Hzin p yu cu

DcPhn cc ha

Tch hp, rng chm 3 dB vi gc phng vikhong 30o, v gc nng 40o, 17 dBi GainAnten

Bng 3.6: Cc thng s k thut Module v Anten thu bao (tip...)


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3.2.3.2 Ni dung cng vic trin khai

Ni dung cc cng vic trin khai bao gm:

Ph chun thit k trm v nhng yu cu v in, c kh v dn dng i vi viclp t phn cng ULAP trn mng.

Thc hin nhiu Test truy nhp khc nhau bao gm kh nng kt ni v tuyn gia

cc thnh phn mng ULAP khc nhau nh im truy cp, Module thu bao v

CPEs.

Thc hin kim tra di v s truyn sng xc nhn vng ph sng ngoi tri

(trn thc t so vi phng on) cho nhng mi trng khc nhau ( th, th trn

v nng thn).

Thc hin kim tra throughput cng nhn cc cell v ngng dung lng mng.

Thc hin cc Test nhiu thu bao v cc thu bao s dng ng thi cng nhn

s hot ng ca mng trong nhng hon cnh khc nhau.

Kim tra cc dch v thu bao khc nhau nh d liu, v tuyn, VoIP, v cc ng

dng khc.

Thu thp KIPs nh gi tr ca h thng, sa li, tc truyn d liuv thc hin cng phn tch d liu nh gi hiu qu ca gii php.

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3.2.3.3 S chung v mng ca ULAP WiMAX c trnh by trong hnh

Hnh 3.8: Cu hnh mng chung ULAP

Cell ca ULAP s c kt ni vi im chuyn mch tp m im ny s kt thc

ti mng d liu ca nh khai thc s dng backhaul hin c. Backhaul c th trn

Canopy hoc trn bt k cng ngh no c h tr trn mng HNPT. Throughput thc ts ph thuc vo dung lng c phc v ca ULAP cell.

- 71 -


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Hnh 3.9: Cu hnh mng

3.2.3.4 Cc thnh phn h thng v thit b kim tra c yu cu

4 sector MotoWi4 Ultra Light 3500Access Point 1 b

1 sector MotoWi4 Ultra Light 3500Access Point 2 b

Thit b cung cp in ULAP 3 b

Module thu bao ULAP MotoWi4 20 b

Thit b cp ngun module thu bao 20 b

Module backhaul Canopy v cp ngun v d liu 4 b

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Dng c treo cho Canopy Module backhaul 4 b

C t nht 1PC demo vi Ethernet v dung lng d liu truyn dung kim tra.

P3 vi 512M RAM hoc tng ng

t nht 1 cp PC chy Linux Redhat WS 4.0 cho NMS

Cc loi cp v chuyn i in

CAT5 chun vi ni RJ45( chiu di cp khng qu 100m) cho mi

ULAP v CPE.

C thm t nht 1 cp cho mi thnh phn mng thm vo.

B chuyn i in c th chuyn t cm tiu chun M sang tiu chun

VN nu cn.

Chuyn mch lp 3 vi cc cng 12 10/100 1 b

Router VN v 100base T/100 base T mng

2-3 Linksys 8 port routers hoc c th tng ng.

Cc PC c th chi cc tr chi ging nhau 2 b

3.2.3.4.1 Phn mm

CNUT phin bn 4 chy phn mm Windows XP vi phin bn Runtime v PERL

5.8 hoc phin bn tt hn.

H thng qun l thnh phn Prizm 20 bn quyn module thu bao

H thng qun l v nhn thc bng thng (BAM) bn quyn my ch 2.0

Phn mm chy ULAP phin bn 8.0

Phn mm CPE ngoi tri phin bn 8.1

C s d liu

C s d liu phn mm my ch MySQL ( gm Linux Redhat WS phin bn 4.0)

Cng c

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Cng c nng cp CNUT

Phn mm khch hng/my ch WinFTP

3.2.4 Cu hnh th nghim

Hnh 3.10: Cu hnh th nghim WiMAX di ng HNPT

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3.2.4.1 Cc m hnh th nghim

3.2.4.1.1 Dch v d liu

Bao gm cc bi th nghim PING, FTP, duyt

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