50761116 3338397 cong ngh truy nhp trong mng ngn

7/31/2019 50761116 3338397 Cong Ngh Truy Nhp Trong Mng NGN

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TNG CNG TY BU CHNH VIN THNG VIT NAM

HC VIN CNG NGH BU CHNH VIN THNG

TRUNG TM O TO BU CHNH VIN THNG I

---------------------------------

Ti liu ging dy

CNG NGH TRUY NHP TRONG MNG NGN

Bin son: Nguyn Vit Hng

H ni thng 5 nm 2007

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Nguyn Vit Hng Mng Vin thng Vin thng I Cng ngh truy nhp trong NGN

MC LC

MC LC ....................................................................................................... ...................iDANH MC HNH V ................................................................................................... ...iDANH MC BNG BIU ............................................................................ ..................iii

T VIT TT ........................................................................................... .......................ivPHN I: GII THIU CHUNG ........................................................................... .............1Chng 1: Pht trin ca mng vin thng v phng thc truy truy nhp ........................2

1.1 Cc th h mng truy nhp v mng vin thng tng ng .....................................21.1.1 Mng NGN v cc cng ngh truy nhp............................................................22.1.1 Nhng giai on pht trin ca mng truy nhp......................................... ........3

1.2 Cng ngh truy nhp hu tuyn ...................................................... .........................61.3 Cng ngh truy nhp v tuyn .................................................... .............................61.4 Nhng cng ngh truy nhp hu tuyn cnh tranh .......................................... .........6

1.1.1 Cng ngh PLC..................................................................................... .............6

1.1.2 Cng ngh CM (CATV)................................................................. ....................81.5 So snh v nh gi cc cng ngh truy nhp .................................. ........................9PHN II: CNG NGH TRUY NHP HU TUYN ................................................... 10Chng 2: H cng ngh xDSL ................................................................... ....................11

2.1 Cng ngh trong h xDSL .................................................................................. ...112.2 Kin trc h thng ........................................................................................ ..........15

1.1.3 Thit b nh cung cp dch v kt ni...................................................... .........151.1.4 Pha khch hng..................................................................... ..........................161.1.5 Mch vng thu bao....................................................................... ..................16

2.3 ADSL, ADSL2, ADSL2+ ......................................................................... ..............16

1.1.6 ADSL...................................................................................... .........................172.3.1.1 K thut iu ch ......................................................... ..............................172.3.1.2 K thut truyn dn song cng ................................................... ...............182.3.1.3 Nguyn l thu pht ............................................................... .....................21

1.1.7 ADSL2................................................................................... ..........................222.3.1.4 Gii thiu chung ............................................................................. ...........222.3.1.5 Cc tnh nng lin quan n ng dng ....................... ...............................232.3.1.6 Cc tnh nng lin quan n PMS-TC .................................. .....................242.3.1.7 Cc tnh nng lin quan n PMD .................................................. ...........24

1.1.8 ADSL2+......................................................................................... ..................262.3.1.8 Gii thiu chung ........................................................................... ............262.3.1.9 M rng bng tn ............................................................... .......................262.3.1.10 Ghp t tc cao hn ............................................ .........................272.3.1.11 Mt s tnh nng khc ca ADSL2+ .................................................. ......28

2.4 HDSL, HDSL2,SHDSL, HDSL4 .......................................................... .................291.1.9 HDSL............................................................................................. ..................29

2.4.1.1 HDSL nguyn bn ................................................................... ..................292.4.1.2 Kh nng v ng dng HDSL ........................................ ...........................292.4.1.3 Truyn dn HDSL .......................................................... ...........................30

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1.1.10 HDSL th h th hai (HDSL2)........................................................... ............311.1.11 SHDSL.......................................................................................... .................311.1.12 HDSL4....................................................................................... ....................31

2.5 VDSL v VDSL2 ........................................................................ ..........................311.1.13 VDSL........................................................................................ .....................311.1.14 VDSL2..................................................................................... ......................33

2.6 Tnh hnh trin khai ti Vitnam ................................................................... .........34Chng 3: Cng ngh truy nhp quang .......................................................................... .35

3.1 Cc mng PON ....................................................................................................... 353.2 APON .............................................................................................................. .......38

1.1.15 Cu hnh tham chiu.................................................................................. .....383.2.1.1 OLT ..................................................................................... .....................393.2.1.2 ONU ............................................................................................ .............403.2.1.3 ODN ............................................................................................ .............41

1.1.16 Cc c t cho APON............................................................................ .........421.1.17 Cu trc phn lp APON............................................................................ ....43

3.2.1.4 Lp vt l .......................................................................... ......................443.2.1.5 Lp hi t truyn dn TC .................................................. ........................443.3 EPON ...................................................................................................... ...............44

1.1.18 Kin trc EPON.................................................................. ...........................441.1.19 M hnh ngn xp EPON.................................................... ...........................451.1.20 Giao thc EPON............................................................................................. 461.1.21 Bo mt trong EPON..................................................................................... .461.1.22 Nhng bc pht trin tip theo....................................................... ..............47

3.4 Metro Ethernet ............................................................................. ..........................481.1.23 Li ch khi dng dch v Ethernet............................................... ...................48

3.4.1.1 Tnh d s dng .............................................................................. ...........483.4.1.2 Hiu qu v chi ph ................................................................................ ...483.4.1.3 Tnh linh hot .................................................................... .......................49

1.1.24 M hnh dch v Ethernet ................................................................. .............493.4.1.4 Kt ni Ethernet o ............................................................................ .......493.4.1.5 Khun kh nh ngha dch v Ethernet................................. ...................50

1.1.25 Cc thuc tnh dch v Ethernet........................................ .............................523.4.1.6 Ghp dch v .................................................................... ........................523.4.1.7 Gp nhm ............................................................................................ ......523.4.1.8 c tnh bng thng ................................................... ..............................523.4.1.9 Thng s hiu nng ...................................................... ............................533.4.1.10 Vn an ninh mng (Network security) ................................ ................53

1.1.26 Tnh hnh trin khai...................................................................... ..................531.1.27 Nhng cng ngh c s dng............................................................. ........56

3.4.1.11 Truyn ti Metro Ethernet qua SONET/SDH ..........................................563.4.1.12 RPR ........................................................................................ .................56

PHN III: CNG NGH TRUY NHP V TUYN ......................... ...........................58Chng 4: Cc mng truy nhp khng dy bng rng .....................................................59

4.1 Gii thiu chung ................................................................................................ .....59

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4.2 Pht trin ca truy nhp v tuyn hi t n 4G ...................................................601.1.28 H thng thng tin di ng 2G v nn tng CDMA.......................................61

4.2.1.1 GSM ............................................................................................. .............614.2.1.2 IS-95 .................................................................................................... ......624.2.1.3 GPRS ..................................................................................................... ...63

1.1.29 H thng 3G.................................................................................. .................63

4.2.1.4 IMT-2000 .................................................................. ..............................634.2.1.5 GPP2 & cdma2000 .......................................................................... ..........64

1.1.30 WLAN........................................................................................................ ....651.1.31 Wimax............................................................................................ ................661.1.32 H thng 4G.................................................................................. .................67

4.3 So snh nh gi cc cng ngh ............................................................... ..............67Chng 5: Truy nhp qua v tinh .............................................................................. .......69

5.1 Gii thiu chung ................................................................................................ .....695.2 H thng VSAT ........................................................................................ ..............71

Chng 6: WLAN v WI-FI ......................................................................... ...................72

6.1 Gii thiu chung ................................................................................................ .....726.2 Kin trc WLAN ............................................................................................ ........721.1.33 Cu hnh mng WLAN ................................................................................ ..72

6.2.1.1 Cu hnh mng WLAN c lp .......................................... ......................736.2.1.2 Cu hnh mng WLAN c s ............................................ ........................736.2.1.3 Kin trc y ca WLAN ........................................................ .............74

1.1.34 M hnh tham chiu c bn IEEE 802.11.......................................... ............756.3 Chun cng ngh ............................................................................................. ......766.4 H thng thit b ................................................................................................ .....79

1.1.35 Cc card giao din mng v tuyn ............................................................... ..79

1.1.36 Cc im truy nhp v tuyn ................................................................. ........791.1.37 Cu ni v tuyn t xa..................................................... ..............................806.5 Bo mt ................................................................................................ .................81

1.1.38 Tp dch v ID (SSID)........................................................ ...........................811.1.39 Giao thc bo mt tng ng hu tuyn (WEP)........................................821.1.40 Lc a ch MAC...................................................................................... ......83

6.6 Tnh hnh trin khai ti Vitnam ..................................................................... ........84Wimax ..................................................................................................................... ........85

6.7 Gii thiu chung ................................................................................................ .....851.1.41 Lch s Wimax.......................................................................... .....................851.1.42 Khi nim Wimax......................................................... .................................861.1.43 Bng tn................................................................................ .........................86

6.8 Kin trc Wimax ................................................................................ ....................871.1.44 Cu hnh mng..................................................................... ..........................87

6.8.1.1 Cu hnh mng im- a im (PMP) ................................. .....................876.8.1.2 Cu hnh mt li MESH ............................................................ .............87

1.1.45 M hnh phn lp...................................................................... .....................886.9 Chun cng ngh ............................................................................................. ......89

1.1.46 Chun 802.16-2001...................................................................... ..................90

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1.1.47 Chun 802.16a-2003........................................................... ...........................911.1.48 Chun 802.16c-2002........................................................... ...........................911.1.49 Chun 802.16d-2004................................................................... ...................911.1.50 Chun 802.16e-2005 .......................................................... ...........................92

6.10 Mt s c im k thut ca Wimax ....................................... ...........................921.1.51 Lp vt l ................................................................................... ...................92

6.10.1.1 Khi nim OFDM ................................................................................ ...936.10.1.2 OFDMA cho lp vt l v tuyn MAN-OFDMA ...................................946.10.1.3 SOFDMA theo t l (S-OFDMA) .................................. .........................946.10.1.4 Knh con ha ....................................................................................... ...95

1.1.52 Lp MAC......................................................................................... ..............976.11 H thng thit b ........................................................................................ ...........996.12 Bo mt ............................................................................................ ..................1036.13 Tnh hnh trin khai ti Vitnam ............................................................... ..........103

TI LIU THAM KHO..................................................................................... .........105....................................................................................................... ........................106

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DANH MC HNH V

Chng 2:Hnh 1.1: Mng th h sau v cc cng ngh truy nhp.......................................3Chng 3:Hnh 1.2: S ra i ca cc dng thit b truy nhp.............................................4Chng 4:Hnh 1.3: Thit b DLC th h 3.................................................................. .........5

Chng 5:Hnh 1.4: Thit b truy nhp IP cho mng th h sau........................................ ....6Chng 6:Hnh 2.1: Lch s pht trin ca cc cng ngh trong h xDSL.........................11Chng 8:Hnh 2.2: B cung cp mch vng thu bao s xDSL........................................15Chng 9:Hnh 2.3: Cu trc h thng ADSL............................................ ........................16Chng 10:Hnh 2.4: ADSL s dng v khng s dng k thut trit ting vng...............18Chng 11:Hnh 2.5: Phn chia bng tn ca k thut FDM.................................... ...........19Chng 12:Hnh 2.6: Phn chia bng tn ca k thut EC..................................................20Chng 13:Hnh 2.7 Phn tch tn hiu ln, xung bng phng php kh ting vng.....20Chng 14:Hnh 2.8 : S khi thu v pht ADSL................................................... .......21Chng 15:Hnh 2.9: Tc s liu ng xung ca ADSL2+ so vi ADSL2................27

Chng 16:Hnh 2.10: Ghp hai ng ADSL2+....................................................... ........28Chng 17:Hnh 2.11: Kh nng cung cp dch v ca k thut VDSL..............................32Chng 19:Hnh 2.12: Tnh hnh trin khai xDSL ti Vit nam ca VNPT........................34Chng 20:Hnh 3.1: S logic h thng mng PON......................................................36Chng 21:Hnh 3.2: Cu hnh chung ca mt mng PON................................................38Chng 22:Hnh 3.3: Cu hnh tham chiu APON..................................... ........................38Chng 23:Hnh 3.4: Cc khi chc nng trong OLT........................................................39Chng 24:Hnh 3.5: Cc khi chc nng trong ONU.......................................................40Chng 25:Hnh 3.6: Cu hnh vt l ca ODN........................................ .........................42Chng 26:Hnh 3.7: Cu trc phn lp mng APON......................................... ...............43

Chng 27:Hnh 3.8: Ngn xp EPON................................................................ ...............46Chng 28:Hnh 3.9 Mng MAN th nghip ti thnh ph H Ch Minh..........................53Chng 29:Hnh 3.10 Mng MAN ti Ninh Bnh ...................................................... ........55Chng 30:Hnh 4.1 : Cc cng ngh truy nhp v tuyn..................................................59Chng 31:Hnh 4.2: Xu hng hi t ca cng ngh truy nhp v tuyn.........................60Chng 32:Hnh 4.3: Mc lch s ca truy nhp v tuyn................................................ ..61Chng 33:Hnh 4.4: S pht trin ln 4G t cc cng ngh WAN....................................61Chng 34:Hnh 4.5: H thng IMT 2000.............................................................. ............63Chng 35:Hnh 4.6 : Cc cng ngh truy nhp v tuyn cnh tranh.................................68Chng 36:Hnh 5.1 in thoi di ng Iridium...................................... ..........................70Chng 37:Hnh 6.1 Qu trnh pht trin WLAN.................................................... ...........72Chng 38:Hnh 6.2: Cu hnh mng WLAN c lp........................................................73Chng 39:Hnh 6.3 Cu hnh mng WLAN c s............................................................74Chng 40:Hnh 6.4: Cu hnh WLAN dng b lp................................................ ..........74Chng 41:Hnh 6.5: Kin trc WLAN y ...................................... ............................75Chng 42:Hnh 6.8: M hnh tham chiu c bn IEEE 802.11.......................... ..............76Chng 43:Hnh 6.6: M hnh tham chiu....................................................................... ...78Chng 44:Hnh 6.9: im truy nhp AP............................................... ............................80Chng 45:Hnh 6.10: Cu ni v tuyn............................................. ...............................81

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Chng 46:Hnh 7.1: Cu hnh im-a im (PMP).............................................. ...........87Chng 47:Hnh 7.2: Cu hnh mt li MESH..................................................... ............88Chng 48:Hnh 7.3: Cc phn lp giao thc Wimax cho hai lp cui cng.....................89Chng 49:Hnh 7.4: V tr ca chun IEEE 802.16 trong cu trc chun IEEE 802 ........90Chng 50:Hnh 7.5: Qu trnh truyn dn.................................................................. .......92Chng 51:Hnh 7.6: OFDM vi 9 sng mang con ..................................... .....................94

Chng 53:Hnh 7.7: n nh khe thi gian trong OFDM.................................................96Chng 54:Hnh 7.8: Phn lp MAC v cc chc nng.....................................................98

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DANH MC BNG BIU

Chng 7:Bng 2.1: Cc cng ngh trong h xDSL............................................. ..............13Chng 18:Bng 2.2: Tc khong cch cc loi VDSL.................................... .............32Chng 52:Bng 7.1: Cc tham s ca SOFDMA ................................................ .............95

Chng 55:Bng 7.2: Thng hiu ca cc nh cung cp thit b Wimax..........................99

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T VIT TT

T VIT TT NGHA TING ANH NGHA TING VIT

ADC Analog-to-Digital Converter Bin i s tng t

AAA Authentication, authorization andAccount

Nhn thc, cp php v lp tikhon

AAS Adaptive Antenna System H thng anten thch ng

ACK Acknowledgment Xc nhnADSL Asymmetric Digital Subcriber Line ng dy thu bao s bt i

xng

AES Advance Ecryption Standard Chun mt m nng cao

AK Authorization Key Kha nhn thc

AMC Adaptive Modulation and Coding iu ch v m ha thch ngANSI American National Standards

InstituteVin Quc Gia M

APON ATM Passive Optical Network Mng quang th ng truyn dnkhng ng b

ARQ Automatic Retransmission Request Yu cu truyn li t ng

ASN Access Service Network Mng dch v truy nhpATM Asynchronuos Transfer Mode Phng thc truyn dn khng

ng b

ATM Asynchronous Transfer Mode Phng thc truyn khng ng bATP Access Termination Point im tham chiu u cui truy

nhpAWGN Additive White Gauussian Noise Nhiu Gauss trng cng

BE Best Effort Dch v n lc tt nhtBER Bit Error Ratio T s tn hiu trn nhiuB-ISDN B-Inergrated Service Digital Network Mng s cc dch v tch hp bng

rng

BPSK Binary Phase shift Keying Kha chuyn pha nh phn

BR Bandwidth Request Yu cu bng thngB-RAS BroadBand Remote Access Server My ch truy nhp bng rng t xa

BS Base Station Trm gc

BSN Block Sequence Number S th t khi

BTC Block Turbo Code M Turbo khi

BW Bandwidth Bng thng

BWA Broadband Wireless Access Truy nhp khng dy bng rng

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C/I Carrier to Interference Ratio T s tn hiu/ nhiu

CA Collision Avoidance Trnh xung tCAP Carrierless Amplitude and Phase

modulationiu ch bin pha khng sngmang

CBC Cipher Block Chaining Chui khi m ha

CC Confirmation Code M xc nhn

CCI Co-Channel Interference Nhiu knh lin kt

CCK Complementary Coded Keying Kha m ha b sungCDMA Code Division Multiple Access a truy nhp phn chia theo m

CDMA Code Division Multiple Access a truy nhp phn chia theo m

CID Connection Identifier Nhn dng kt niCO Central Office Trung tm chuyn mch

CP Cyclic Prefix Tin t tun hon

CPE Customer Premises Equipment Thit b truyn thng c nhnCPE Customer Premises Equipment Thit b truyn thng c nhn

CPS Common Part Sublayer Lp con phn chung

CRC Cyclic Redundancy Check Kim tra d vng tun hon

CS Convergence Sublayer Lp con hi t

CSMA Carrier Sense Multiple Access a truy nhp cm nhn sng mang

CSN Connection Service Network Mng dch v kt ni

CTC Concatenated Turbo Code M Turbo xon

DAMA Demand Assigned Multiple Access a truy nhp n nh theo nhu cu

DCD Downlink Channel Descriptor Miu t knh ng xung

DCF Distributed Control Function Chc nng iu khin phn tn

DES Data Encryption Standard Chun mt m ha d liuDFE Decision Feedback Equalization Phn on hi tip quyt nh

DFS Dynamic Frequence Selecton La chn tn s ngDFT Discrete Fourier Transform Bin i Fourier ri rc

DHCP Dynamic Host Configuration Protocol Giao thc cu hnh Host ng

DL Downlink ng xung

DLFP Downlink Frame Preamble Tin t khung ng xungDMT Discrete Multiple Tone Modulation iu ch a tn ri rc

DSA Dynamic Services Addition B sung cc dch v ng

DSC Dynamic Services Change Chuyn i cc dch v ng

DSL Digital Subcriber Line ng dy thu bao s

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DSLAM DSL Access Module Khi truy nhp DSL

EAP Extensible Authentication Protocol Giao thc nhn thc m rng

EC Encryption Control iu khin mt m ha

ECB Electronic Code Book Sch m in t

EDCA Enhanced Distributed Control Access Truy nhp iu khin phn tnnng cao

EDGE Enhanced Data Rates Cc tc d liu c nng cp

EKS Encryption Key Sequence Chui kha mt mETSI European Technical Standards

InstituteVin Chun k thut Chu u

ETSI European TelecommunicationsStandards Institute

Vin cc chun vin thng Chuu

EV-DO Enhanced Version- Data Only Ch d liu-phin bn nng cao

Ex Exchange Tng i

FBSS Fast Base Station Switch Chuyn mch trm gc nhanh

FCH Frame Control Header Tiu iu khin khungFDD Frequency Division Duplexing Song cng phn chia theo tn s

FDD Frequence Division Duplex Song cng phn chia theo tn s

FDM Frequence Division Mutiplexing Ghp knh phn chia theo tn sFEC Forward Error Correction Sa li trc

FEC Forward Error Crrection Hiu chnh li trcFEXT Far-End Crosstalk Xuyn m u xaFFT Fast Fourier Transform Bin i Fourier nhanh

FFT Fast Fourier Transform Chuyn i Fourier nhanhFSAN Full Service Access Network T chc iu hnh mng truy nhp

dch vu y

FSH Fragmentation Subheader Tiu con phn onFTTC/B Fiber To The Curb/Building Cp quang ti khu vc/cao cFTTCab Fiber To The Cabinet Cp quang n t phn phiFTTEx Fiber To The Exchage Cp quang ti tng iFTTH Fiber To The Home Cp quang ti nhGMS Global System for Mobile

communicationH thng truyn thng di ng toncu

GPC Grant Per Connection Cp pht trn mi trm gc

GPRS Generalized Packet Radio Service Dch v v tuyn gi chung

GPSS Grant Per Subscriber Station Cp pht trn mi trm thu bao

GSM Global System For Mobile H thng ton cu cho truyn

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Communicatons thng di ng

HARQ Hybrid Automatic RetransmissionRequest

Yu cu truyn li t ng kt hp

HCS Header Check Sequence Th t kim tra tiu HFC Hybrid Fiber Coaxial Mng lai cp quang cp ng trc

HHO Hard HandOver Chuyn giao cng

HSDPA High Speed Downlink Packet Access Truy nhp gi ng xung tc cao

HSUPA High Speed Uplink Packet Access Truy nhp gi ng ln tc

cao

HT Header Type Loi tiu IDFT Inverse Discrete Fourier Transform Bin i ngc Fourier ri rc

IEEE Institute of Electrical and Electronic

Engineers

Vin cc k s in v in t

IFFT Inverse Fast Fourier Transform Bin i fourier ngc nhanh

IMT International Mobile Telecommunications

Vin thng di ng quc t

IP Internet Protocol Giao thc Internet

IP Internet Protocol Giao thc lin mngISDN Integrated Services Digital Network Mng s a dch v

ISI Inter-Symbol Interference Nhiu gia cc Symbol

ISM Industrial Scientific and Medical Cng nghip khoa hc v ha hc

ISP Internet Service Provider Nh cung cp dch v Internet

KEK Key Encryption Key Kha mt m kha

LAN Local Area Network Mng vng cc bLMDS Phn phi dch v ni ht

LOS Line Of Sight Tm nhn thngLPF Low Pass Filter B lc thng thp

LSB Least Significant Bit Bt t ngha nht

MAC Medium Access Control iu khin truy nhp phng tin

MAN Metropolitan Area Network Mng vng thnh th

MDHO Marco Diversity Handover Chuyn giao a dng bng Marco

MIMO Multiple Input Multiple Output Nhiu u vo nhiu u ra

MIP Mobile Internet Protocol Giao thc Internet di ng

MISO Multiple Input Single Output Nhiu u vo mt u raMMDS Phn phi dch v a knh a im

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MPLS Multi Protocol Label Switching Giao thc chuyn mch nhn ngin

MRC Maximum Ratio Combining Kt hp t s cc i

MS Mobile Station Trm di ng

MSB Most Significant Bit Bt ngha nht

NACK Non-ACK Khng xc nhn

NAP Network Access Provider Nh cung cp truy nhp mngNEXT Near-End Crosstalk Xuyn m u gnNGN Next Generation Network Mng k tip

NLOS Non Line Of Sight Khng tm nhn thngNTE Network Termination Equipment Thit b u cui mng

OFDM Orthogonal Frequence DivisionMultiplexing

Ghp knh phn chia theo tn s

trc giao

OFDMA Orthogonal Frequence DivisionMultiple Access

a truy nhp phn chia theo tn strc giao

OLT Optical Line Terminal u cui ng dy quangONU Optical Network Unit n v mng quang

PAN Personal Area Network Mng c nhn

PCF Point Control Function Chc nng iu khin im

PDA Personal Digital Assistant H tr c nhn dng k thut s

PDU Protocol Data Unit n v d liu giao thc

PHS Payload Header Suppression Nn tiu ti trngPKM Privacy Key Management Qun l kha bo mt

PLMN Public Land Mobile Network

cng

Mng di ng mt t cng

PLOAM Physical Layer Operation andManagement

Qun l v hot ng ca tng vt l

PMD Physical Medium Dependent Mi trng vt l ph thuc

PMP Point to Multipoint im-a imPMS Physical Medium Specific c tnh mi trng vt l

PN Packet Number S giPON Passive Optical Network Mng quang th ngPOTS Plain Old Teliphone Service Dch v truyn thng

PPP Point to Point Protocol Giao thc im-im

PS Physical Slot Khe vt l

PSCN Packet Switched Core Network Mng li chuyn mch giPSD Power Spectral Density Mt ph cng sut

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PSH Packing Subheader Tiu con giPSTN Public Switch Telephone Network Mng in thoi chuyn mch cng

cng

PTP Point to Point im-im

QAM Quadrature Amplitude Modulation iu ch bin cu phng

QPSK Quadratura Phase Shift Keying Kha chuyn pha cu phng

RAN Region Area Netwwork Mng vng a phng

REQ Request Yu cuRFI Radio Frequency Interference Nhiu tn s v tuyn

RLC Radio Link Controller B iu khin lin kt v tuyn

RS Reed-Solomon M Reed-Solomon

RTG Receive Transition Gap Khong trng chuyn giao u thu

Rx Receiver u thu

SA Security Association Kt hp bo mt

SAID Security Association Identifier Nhn dng kt hp bo mt

SAP Service Access Point im truy nhp dch vSDH Synchronous Digital Hierarchy H thng phn cp k thut s ng

b

SDU Service Data Unit n v d liu dch v

SHA Secure Hash Algorithm Thut ton xo trn bo mtSN Service Node Node dch v

SNR Signal to Noise Ratio T s tn hiu trn nhiuSOFDMA Scalable Orthogonal Frequence

Division Multiple AccessGhp knh phn chia theo tn strc giao theo t l

SOHO Small Office Home Office Vn phng gia nh vn phng nhSONET Synchronous Optical Network Chun xc nh truyn thng trn

cp quang

SS Subscriber Station Trm thu bao

SSCS Specify ServicesConvergenceSublayer

Lp con hi t cc dch v ring

STC Space Time Code M khng gian thi gianSTM Synchronuos Transfer Mode Trng chuyn mch ng bTC Transmission Convergence Lp hi t truyn dn

TDD Time Division Duplex theo thi gian Song cng phn chia

TDM Time Division Multiplexing theo thigian

Ghp knh phn chia

TDMA Time Division Multiple Access a truy nhp phn chia theo m

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TDMA Time Division Multiplexing Access a truy nhp phn chia theo thigian

TE Termination Equipment Thit b u cui

TEK Traffic Encryption Key Kha mt m lu lng

TFTP Trivial File Transfer Protocol Giao thc truyn tp thng thng

TLS Transport Layer Security Bo mt lp truyn ti

TLV Type/Length/Value Loi/ di/ Gi tr

Tx Transmiter u pht

UCD Uplink Channel Descriptor Miu t knh ng ln

UGS Unsolicited Grant Service Dch v cp pht khng kt hp

UL Uplink ng ln

UMTS Universal Mobile TelecommunicationSystem

H thng vin thng di ng toncu

UMTS UTRA UMTS terrestrial Radio Access Truy nhp v tuyn trn mt t

UNI User Network Interface Giao din ngi dng mng

UTRAN UMTS terrestrial Radio AccessNetwork

Mng truy nhp v tuyn trn mtt UMTS

VoIP Voice Over IP Thoi qua IPVTU VDSL Transmission Unit Khi truyn dn VDSLVTU-O VDSL Transmission Unit CO Khi truyn dn VDSL pha tng

iVTU-R VDSL Transmission Unit Remote Khi truyn dn VDSL pha thu

bao xa

WAN Wide Area Network mng din rngWDM Wavelength Division Multiplexing Ghp knh a bc sng

WEP Wired Equivalent Privacy Bo mt ng lng hu tuyn

Wi-Fi Wireless Fidelity

WLAN Wireless LAN Mng LAN khng dy

WMAN Wireless MAN Mng MAN khng dy

WME Wi-Fi Mutlimedia Extensions Nhng m rng

a phng tin Wi-Fi

WPA Wi-Fi Protected Access Truy nhp c bo v Wi-FixDSL Digital Subcriber Line H cng ngh DSL

XOR Exclusive-OR Hm cng modul

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PHN I: GII THIU CHUNG

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Chng 1:Pht trin ca mng vin thng v phng thc truy truynhp

1.1Cc th h mng truy nhp v mng vin thng tng ng

1.1.1Mng NGN v cc cng ngh truy nhp

nh ngha NGNMng vin thng th h mi c nhiu cch gi khc nhau nh Mng a dch v,

Mng hi t, Mng phn phi hay mng nhiu lp. Cho ti nay cc t chc v cc nhcung cp thit b vin thng trn th gii rt quan tm n NGN nhng vn cha c mtnh ngha r rng. Do vy ta ch c th tm nh ngha NGN nh sau:

NGN l mng c h tng thng tin duy nht da trn cng ngh chuyn mchgi, trin khai cc dch v mt cch a dng v nhanh chng, l s hi t gia thoi vd liu, gia c nh v di ng.

c im NGNNGN c 4 c im chnh:

Nn tng l h thng m. NGN l do mng dch v thc y nhng cc dch v trn NGN phi c

lp vi mng li. NGN l mng chuyn mch gi da trn mt giao thc thng nht. L mng c dung lng ngy cng tng, c tnh thch ng ngy cng tng

v c dung lng p ng nhu cu.Trong NGN giao thc IP thc t tr thnh giao thc ng dng vn nng c p

dng lm c s cho mng a dch v. Hin ti mc d vn cn gp nhiu kh khn so vi

mng chuyn mch knh v kh nng h tr lu lng thoi v cung cp cht lng dchv m bo cho s liu, nhng vi tc thay i nhanh chng nhiu cng ngh miang c p dng s sm khc phc iu ny trong tng lai gn.Cc cng ngh truy nhp v mng NGN

Nh trong hnh 1.1 kt ni ngi dng vo mng NGN ngi ta c th s dngmt cng ngh hoc c th kt hp mt vi cng ngh khc nhau to ra hng lotnhng phng thc kt ni khc nhau. Nhng cng ngh kt ni hin nay ang c sdng ph bin bao gm :

V tuyn (GSM, 3G, 4G, WLAN, WMAN) Hu tuyn xDSL, PON, CATV, PLC

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Chng 2:Hnh 1.1: Mng th h sau v cc cng ngh truy nhp

Tuy nhin, t c cu trc nh mong mun trn hnh 1.1 th mng truy nhpni ring v mng vin thng ni chung phi tri qua nhng giai on qu vi nhiutrng thi khc nhau tng ng vi nhng xut pht im (mng truyn s liu, thoitruyn thng PSTN, mng di ng, mng di ng ni ht) v gii php s dng khcnhau. Chng ta c th tng kt li (nhn t hng pht trin t mng PSTN) nhng th hca mng truy nhp nh trong mc sau.

2.1.1Nhng giai on pht trin ca mng truy nhp

Hnh 1.2 cho chng ta thy tin trnh pht trin ca cc thit b truy nhp trongmng Vin Thng.

Dng thit b h tr dch v bng rng u tin v c tch hp pha thu bao lDLC th h 3 hay NDLC ra i vo nhng nm cui th k 20. Thit b ny c nhiuim tng ng vi ATM DSLAM do cng s dng mt cng ngh v kin trc tng tnhau ( hiu thm v DLC xem ph lc A). NDLC th u ni v phi hp hot ng

vi nhau to thnh mt mng ATM din rng thng nht, chuyn mch gi vi bngthng tng i ln cho php cung cp cc dch v d liu mt cch tng i mm do(Hnh 1.3). c tnh ca dng thit b ny nh sau:

Cung cp gii php truy nhp bng rng tm thi qua mng li ATM. S dng cng ngh xDSL truy nhp d liu tc cao. Chun V5.x giao din vi mng PSTN. Kt ni ATM vi mng ng trc hay qua mng IP. H tr cc dch v thoi/fax, ISDN v d liu bng rng.

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Chng 3:Hnh 1.2: S ra i ca cc dng thit b truy nhp.

Tuy nhin dng thit b ny c mt s nhc im sau: Bng thng v dung lng hn ch. Nt c chai trong vng ring truy nhp nu phn ln cc thu bao u s

dng dch v xDSL v nt c chai trong mng li ATM. Kh m rng dung lng. Kin trc phc tp, qua nhiu lp (Ip qua ATM qua SDH/DSL). Gi thnh v chi ph tng i cao.

Sau DLC th h 3 l dng thit b truy nhp IP hay IP-DSLAM. y l dng thubao truy nhp tin tin nht hi t nhiu cng ngh nn tng trong mng th h sau NGN.Dng thit b ny chy trn nn tng mng IP, IP-AN vi nhng c im sau:

Bng thng/ Dung lng hu nh khng hn ch (Trn thc t hu nhkhng tc nghn vi bng thng trong khong 1-10Gbps).

Truy nhp bng rng IP.

D dng m rng v tch hp vi mng NGN (Trn nn mng chuyn mchmm). Cung cp tt c cc dch v qua mt mng Ip duy nht mc d h thng ny

vn h tr cc u cui tng t truyn thng. Thit b ny phi hp hotng vi mng IP qua media gateway.

Gi thnh tnh cho tng thu bao v chi ph vn hnh mng thp. Kin trc n gin( IP over SDH)

Nm 1890 Cp ng

1-2G DLCNm 1970

V5 DLCGia thp k90

NGDLCCui thp k

90

Truy nhp IP

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Chng 4:Hnh 1.3: Thit b DLC th h 3.

Trong giai on qu hin nay, vic u t vo mng truy nhp mang li hiuqu v mt kinh t v k thut th ngoi gii php ko thm cp ng n khu vc thubao cn c cch s dng cc thit b truy nhp, quang ha mng truy nhp v tn dng tia nhng cng ngh truy nhp v tuyn, hn na ph hp vi xu th tt yu l tin tmng PSTN ln mng NGN khi m mng ni ht cha sn sng h tr cc thit b truy

nhp IP tin tin nht th cn phi c dng thit b truy nhp p ng tt c cc yu cusau:

H tr cc giao din PSTN truyn thng, cc u cui analog. C kh nng cung cp cc dch v bng rng v cc dch v mi khc. H tr bo hiu V5.x v c th kt ni ti cc tng i ni ht ang s dng

(Tc l lm vic nh l thit b DLC). D dng nng cp, tch hp khi chuyn sang mng NGN. m bo thi gian trin khai v chi ph pht thin thu bao khng qu cao.

Cp

DLCDLC

Trung k

IP

EX

PSTN

ATM

EX

Cp ng

B-RAS

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Chng 5:Hnh 1.4: Thit b truy nhp IP cho mng th h sau.

1.2Cng ngh truy nhp hu tuyn

Hin nay trn th trng nhng nh khai thc vi c s h tng khc nhau a ranhng dch v truy nhp da trn cng ngh khc nhau :

Dial up, xDSL, ISDN da trn cp ng xon CM trn mng cp truyn hnh CATV PLC trn mng cp in lc

Truy nhp quang trn CATV, PLCTuy nhin xt v tnh kinh t cng nh s n nh v gii php k thut h cngngh xDSL vn l gii php hp l trong vng 5 nm ti.

1.3Cng ngh truy nhp v tuyn

Vi s xut hin ca Wimax, cng ngh truy nhp v tuyn cho thy s hi tmt cch r rng, v mng truy nhp v tuyn s tin ti cung cp dch v kt ni c tc cao hn, v s c s tha hip gia tnh di ng v tc (QoS)

1.4Nhng cng ngh truy nhp hu tuyn cnh tranh

1.1.1Cng ngh PLC

Vic s dng mng li phn phi in cho mc ch truyn thng c bit nt nhng nm u ca th k 20. Bng cch s dng phng thc iu ch kho bt tt(turn on-turn off carrier) cc h thng PLC u tin c s dng cho vic truynthng ni b nhm thc hin nhim v iu khin v o c t xa. Nhng cc h thngny tc truyn tin rt thp. Ngy nay vi s pht trin nhanh chng ca cng ngh, cbit l cng ngh sn xut vi mch tch hp cho tng ng dng c bit ASIC

IP hay MPLS

IP hay MPLS switch-router

Chuynmch mm

PSTN

Gateway

Gateway truy nhp

xDSL

My T IP

POTS/PSTN

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(Application Specific Integrated Circiut) cho php PLC c nhng bc pht trin nhyvt v tr thnh mt trong nhng cng ngh truy nhp bng rng, tc cao y hahn.

Trong mt vi nm gn y cng ngh PLC ang pht trin mnh m do nhngnguyn nhn sau:

Nhu cu truy nhp Internet bng thng rng ang bng n. Trong khi cccng ngh truy nhp bng thng rng khc v cc l do khc nhaucha p ng c.

Mng li in h th sn c khp ni, di tn trn ng dyin cha c s dng ht.

i vi cc nh khai thc vin thng mi vic xy dng mng truynhp cung cp dch v trc tip ti khch hng i hi chi phln v tn nhiu thi gian, cng sc .

Trong thc t cc hot ng chun ho h thng truyn thng tc cao

PLC ang c tin hnh rt nhiu quc gia, hng lot h thng PLC tc cao v ang c cn nhc thnh sn phm thng mi.

Ti mi h gia nh, c rt nhiu thit b s liu v thit b in s dngcc cm in, do khng cn phi bn ci nhiu v kh nng truyn thng a nngbng vic s dng cc cm in gia cc thit b in v s liu. Khng ging nh cch thng LAN hng ngoi hoc v tuyn, cc thit b u cui PLC c n nh kt nicao thm ch khi cp in c chn trong tng nh.

Hn na, mt u im i vi vi mng gia nh l PLC cung cp kh nng

kt ni ti mng truy nhp, y l mt tnh nng hp dn ca PLC khi n tha mn ccnhu cu v tc s liu. Thng thng, mng truy nhp ni ht hay on kt ni cuicng n thu bao l phn chi ph tn km nht cho mt h thng truyn thng.

Do nhng c im hp dn nu trn, PLC nhn c s quan tm ht sc cbit ca cc nc Chu u, Bc M, Nht v gn y l mt s nc Chu khc. Chuu, trong nhng nm gn y c kh nhiu cuc th nghim mng truy nhp v mnggia nh s dng cng ngh PLC. Trong nm 1999, ETSI cng t ra mt d n mangtn EP PLT (ETSI Project Powerline Telecommunication) pht trin cc tiu chun vcc c t k thut cho h thng PLC. Thng 3 nm 2000, ti Thu S, din n PLC c thit lp nhm mc tiu lin kt cc thnh vin quan tm n cng ngh PLC baogm 51 thnh vin ti 17 quc gia v 3 lc a. Ti Bc M, lin minh cng nghip BcM thit lp mt t chc c tn l HomePlug nhm thc hin mc tiu cung cp mtdin n to ra cc c t m cho pht trin h thng PLC cho cc sn phm v mngtruy nhp tc cao, mng gia nh s dng cng ngh PLC. Hai lnh vc ng dng hinnay ca PLC l truy nhp ni ht (last- mile access) v kt ni mng trong nh (in- house

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networking). Cc dch v ca PLC c th c cung cp m bo lun sn sng ti mi in v khng cn thi cng cp bao gm:

Truy nhp Internet bng thng rng (ti 45Mbs hoc hn ), cc kt ni nylun online.

Dch v thoi v fax.

Kt ni LAN trong nh (in-house LAN) cho cc my PC v my in. Cc dch v bng hp khc ( house automation, health care...).

Cn c vo dung lng cung cp v cu hnh s dng m ta c th phn loi cngngh PLC.

Xt bng tn s dng, ti Nht, bng tn khng cn ng k cho PLC t 10-450 Khztrong khi ti Chu u l t 10 -148.5 Khz (CENELEC: European Committee forElectronic Technical Standarzation). Cc h thng PLC vn hnh di tn ny s cxem nh l cc h thng PLC bng hp.Gn y nhiu quc gia trong c Nht bt

u cn nhc n vic m rng di tn hot ng cho PLC ln ti 30 Mhz. Ti Chu u,ETSI xc nh k hoch phn b bng tn t 1,6 Mhz n 10 Mhz c n nh dnhring cho truy nhp ni ht, di tn t 10 Mhz n 30 Mhz c u tin dnh cho ngdng mng gia nh (in-house), nhng h thng nh vy c th c coi l cc h thngbng rng. Ti Vit nam EVN th nghip thnh cng PLC ti tr s Trn Nguyn Hn,nhng kh nng trin khai trn din rng vn cn ng.

Nu xt theo cu hnh x dng chng ta c th c nhng cu hnh PLC nh: Cu hnh Fiber-LV (Low Voltage) Cu hnh MV&LV (Medium Voltage & Low Voltage) Cu hnh MV & Wireless Cu hnh FTTH (Fiber to the Home)

Do bn cht s khai ca ng cp in khng phi l truyn dn tn hiu thngtin cho nn khng c mt s m bo hiu nng no khi thc hin truyn thng trn cpin nhn t quan im truyn dn tn hiu. Vn ln nht ca PLC l chng nhiu (docc ngun in hoc ngoi in) v suy hao trn ng dy, cng nh tm kim s chpnhn ca th trng.

V vy, PLC c th gp phi cc c tnh c bit ca knh truyn dn s dng cp

in, nh l cc c tnh tr khng thay i theo thi gian v rt thp ca ng dy in,rt nhiu nhn t gy ra cc dng tp m tn hiu.

1.1.2Cng ngh CM (CATV)

L cng ngh cho php truy xut thng tin tc cao n cc server t xa nh

Internet server hay VoD server qua mng truyn hnh cp (Cp ng trc) vi tc thay

i ph thuc vo h thng modem cp, kin trc mng cp ng trc v lu lng trn

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modem.

Tc theo chiu xung c th ln n 27Mbps, tuy nhin y l dung lng tng

cng ca mi ngi chia ra do cu trc mng dng nhnh, thng th dung lng ca mt

thu bao ch t 1-3Mbps. chiu ln c th t c 10Mbps nhng thng l 1-2,5

Mbpsu im ca modem cp l tn dng c mng truyn hnh cp sn c nn gim

chi ph, cc linh kin tn s cao cn thit cho hot ng ca modem cp tr nn rt r

v c bn i tr. Nhng cng do lm vic tn s cao v c n 90% cp i trong nh

m cc cp ny thng c lp t vi v, cu th nn d gy nhiu cho tiviv cc thit

b khc, gii php y l cn phi i li dy nh. Hn na do vic s dng chung cc

knh ng ln nn d gy tc nghn.

Cc nh khai thc mng cp ng trc ang tin hnh ci tin h tng mng cp

bng cch a thm mng cp quang vo mng cp ng trc thay truyn dn tng t

bng truyn dn s c gi l mng lai ghp HFC: Mng HFC cung cp gn 100 knh

truyn dn tc cao (6 MHz) cho mi knh phn phi cc lung video tng t, s, d

liu ti ngi s dng v c th m rng cc dch v bng rng nh modem cp. Tuy

nhin do ng truyn HFC l chung nn bng thngkh dng cho mi knh khi c nhiu

ngi s dng khng cao bng DSL.

1.5So snh v nh gi cc cng ngh truy nhp

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PHN II: CNG NGH TRUY NHP HU TUYN

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Chng 2:H cng ngh xDSL

2.1Cng ngh trong h xDSL

Nh cp chng 1, xDSL l h cng ngh ng dy thu bao s gm nhiucng ngh c tc , khong cch truyn dn khc nhau v c ng dng vo cc dch

v khc nhau, vi x thay cho cc k t : A, H, V, I, S, Lch s pht trin ca cc cngngh trong h c th hin trong hnh 2.1 .

Chng 6:Hnh 2.1: Lch s pht trin ca cc cng ngh trong h xDSL

C th phn loi xDSL theo c tnh truyn dn gia hai chiu ln v xung nh sau(Bng 2.1 tng kt c im ca mt s cng ngh trong h ):

Truyn dn hai chiu i xng gm: HDSL/HDSL2, SHDSL c chunho v nhng phin bn khc nh: SDSL, IDSL

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Truyn dn hai chiu khng i xng gm ADSL/ADSL. Lite (G.Lite),ADSL2, ADSL2+ c chun ho v mt s tn gi khc cha cchun ho nh: RADSL, UADSL, CDSL.

Cng ngh VDSL, VDSL2 cung cp c dch v truyn dn i xng vkhng i xng.

HDSL/HDSL 2 (High data rate DSL): Cng ngh ng dy thu bao s truyn tc d liu cao HDSL s dng 2 i dy ng trong mi i dy s dng hon tonsng cng cung cp dch v T1 (1,544 Mb/s), 2 hoc 3 i dy cung cp dch v E1(2,048 Mb/s)

SDSL (Single pair DSL): Cng ngh DSL mt i dy truyn i xng tc 784kb/s trn mt i dy, ghp knh thoi v s liu trn cng mt ng dy, s dng m2B1Q. Cng ngh ny cha c cc tiu chun thng nht nn khng c ph bin chocc dch v tc cao. SDSL ch c ng dng trong vic truy cp trang Web, ti nhngtp d liu v thoi ng thi vi tc 128 Kb/s vi khong cch nh hn 6,7 Km v

tc ti a l 1024 Kb/s trong khong 3,5 Km.

SHDSL: L cng ngh kt hp ca HDSL 2 v SDSL vi tc thay i t 192kbpsn 2,134 Mbps, khong cch tng ng vi tc ti a l 2km. Trong thc t, n cth cu hnh dng 2 i dy cung cp tc t 384kbps n 4,264Mbps.

ADSL (Asymmetric DSL), ADSL2, ADSL2+: Cng ngh DSL khng i xngc pht trin t khi xut hin cc nhu cu truy nhp Internet tc cao, cc dch vtrc tuyn, video theo yu cu...vo u nhng nm 90. ADSL cung cp tc truyn dnkhng i xng ln ti 8 Mb/s lung xung v 16- 640 Kb/s lung ln vi khong cch

truyn dn 5km v gim i khi tc ln cao. u im ni bt ca ADSL l cho phpkhch hng s dng ng thi mt ng dy thoi cho c 2 dch v: thoi v s liu.Mt dng ADSL mi gi l ADSL Lite hay ADSL khng s dng b lc xut hin tu nm 1998 ch yu cho ng dng truy cp Internet tc cao, k thut ny khng ihi b lc pha thu bao nn gi thnh thit b v chi ph lp t gim i tuy nhin tc lung xung ch cn 1,5 Mb/s. ADSL2 thm nhng ci tin v iu ch v m ha lmtng hiu qu s dng bng thng. ADSL2+ m rng bng tn cho chiu xung ti 2.2Mhz.

ReachDSL l cng ngh DSL i xng p ng nhu cu ca thu bao v ng dyDSL tc cao cc khong cch xa. b sung cho cng ngh ADSL tiu chun (DMThay G.lite), cc sn phm ReachDSL cung cp tc d liu t 128 kbps n 1 Mbps vc thit k lm vic vi iu kin ng dy v i dy trong nh d di hn. Mttrong cc li ch ca ReachDSL l khng cn phi lp t cc b tch dch v thoi nthun POTS. iu ny cho php khch hng hon ton c th t lp t cc bmicrofilter.Khc vi cc h thng ADSL c di vng thu bao gii hn trong khong 6

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Km k t tng i, cc h thng ReachDSL m rng dch v n hn 6 500 m v hin nay c cc ng dy vt qu 10 Km.

VDSL (Very high data rate DSL): Cng ngh DSL tc d liu rt cao l cngngh ph hp cho kin trc mng truy nhp s dng cp quang ti cm dn c. VDSLtruyn tc d liu cao qua cc ng dy ng xon i khong cch ngn. Tc

lung xung ti a t ti 52 Mb/s trong chiu di 300 m. Vi tc lung xung thp1,5 Mb/s th chiu di cp t ti 3,6 km. Tc lung ln trong ch khng i xngl 1,6- 2,3 Mb/s.

Chng 7:Bng 2.1: Cc cng ngh trong h xDSL.

Cngngh

Tc

Khongcchtruyn

S i

dyng dng

IDSL 144 Kb/s i xng 5km 1 i Truyn thoi v s liu

HDSL

1,544Mb/s ixng

2,048Mb/s ixng

3,6 km 4,5 km

2 i

3 i

Cp lumgT1/E1 truy xutWAN. LAN, truy xut server

HDSL2

1,544Mb/s ixng

2,048Mb/s ixng

3,6 km

4,5 km 1 i

SDSL

768kb/s i xng

1,544Mb/s hoc

2,048Mb/s mtchiu

7 km

3 km 1 i

Nh HDSL nhng thm phntruy xut i xng

SHDSL 5.6Mbps ln/xung

7 km

3 km 1, 2i Kt ni server

ADSL7 Mbps xung, 800kbps ln

5km (tc cngcao thkhongcch cng

1 iTruy xut Internet, video ondemand, interactive multimedia,truy xut LAN t xa

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ngn )

ADSL2 8 Mb/s xung, 1Mbps ln

5km (tc cng

cao thkhongcch cngngn )

nhiu

idy

Truy xut Internet, video on

demand, interactive multimedia,truy xut LAN t xa

ADSL2+24 Mbps xung 1Mbps ln

5km (tc cngcao thkhongcch cngngn )

nhiui

dy(ti32 i)

Truy xut Internet, video ondemand, interactive multimedia,truy xut LAN t xa

ADSL2-RE

8 Mbps down

1 Mbps up

5km (tc cngcao thkhongcch cngngn )

ReachExtend

e

Truy xut Internet, video ondemand, interactive multimedia,truy xut LAN t xa

VDSL

26 Mb/s i xng

1352 Mb/s lung

xung1,5-2,3 Mb/s lungln

300 m

1,5 km

(tu tc)

1 i

Nh ADSL nhng thm

HDTV(truyn hnh tc cao)

VDSL2100Mbpsln/xung G.993.2

300 m

1,5 km

(tu tc)

1 iNh ADSL nhng thmHDTV(truyn hnh tc cao)

Vi mt h cc k thut DSL khc nhau, vic p dng chng sao cho ph hp v c

hiu qu cao l mt vn cn xem xt. Mi loi k thut c nhng tnh nng, c th vim mnh, im yu ring. Trong h xDSL th cc cng ngh bt i xng nh ADSL,ADSL2, ADSL2+ l nhng cng ngh c s dng nhiu nht, ph bin nht trn thgii.

Nhn xt nh gi v c im ca xDSL:

Xy dng tnh mm do mc cn thit h tr cho cc ng dng. Tnhmm do th hin y l: Kh nng h tr nhiu loi hnh dch v, kh

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nng m rng pht trin t mt vi thu bao ti hng ngn thu bao, khnng qun l tin cy mng im - im trong vic h tr nhng ng.

Cho php mng ca nh cung cp dch v NPS v ngi s dng dch vtn dng mt s c tnh ca cu trc c s h tng hin nay nh nhnggiao thc lp 2, 3 ging nh Frame Relay, ATM v IP v tin cy nhngdch v mng. xDSL c th trin khai nhng dch v c da trn cc gi

tin hoc t bo ging nh Frame Relay, IP hoc ATM hay trn nhng dchv knh ng b bit.

xDSL p ng c yu cu i hi thi gian thc, tc cao Kh nng xDSL ngy cng phong ph vi rt nhiu cc phin bn mi nh

ADSL2, HDSL2 Qua nhng kt qu nghin cu, cc nh cung cp dch v tha nhn rng h

cng ngh xDSL khng phi l th h tng lai ca mng truy nhp m chl gii php hin ti ca truy nhp mng.

2.2Kin trc h thng

H thng xDSL bao gm nhng thit b pha nh cung cp dch v, nhng thit bkhch hng, nhng thit b ny c ni vi nhau thng qua mch vng ng dy thubao. Hnh 2.2 th hin kin trc chung ca mt h thng s dng xDSL, hnh 2.3 th hinchi tit nhng thit b trong mt h thng ADSL thng dng

Chng 8:Hnh 2.2: B cung cp mch vng thu bao s xDSL

1.1.3Thit b nh cung cp dch v kt ni

Gm c cc b chia c lp t ni cc mch vng thu bao kt cui trn gi phidy chnh MDF, u ra c hai i dy. i th nht kt ni ti mng chuyn mch thoi

Servertruy nhapInternet

Servertruy nhapIntranet

Servertruyen hnh

theoyeu cau

Serverthong tinquang cao

TCP/IPRouter

ATMSwitch

ADSL 1

ADSL n

ADSL 1

ADSL n

MUX

Nut truy nhap

POTS 1

COThuebao 1

PSTNPSTN

PSTNPSTN

Thuebao n

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cung cp dch v thoi truyn thng. i dy th hai kt ni ti khi kt cui ADSLtrung tm (ATU-C). truyn dn hiu qu, cc khi ATU-C c kt hp vi chc nngghp knh to nn b ghp knh truy nhp DSL (DSLAM) trong tng i trung tm vc kt ni ti mng cc nh cung cp dch v thng qua mng bng rng ATM hoc IP.

1.1.4Pha khch hng

Bao gm cc b chia c lp t ni cc mch vng thu bao kt cui, u ra ktni ti khi kt cui ADSL u xa (ATU-R) ti u cui khch hng s dng ADSL vmt u ti u cui khch hng s dng thoi.

1.1.5Mch vng thu bao

L mt i dy ng xon i ni cm thu bao v tng i trung tm. Tuy nhin, h thng ADSL c th trin khai c trn thc t, th ta phi xem xt c s tngthch ph ca cc dch v ADSL trn mch vng thu bao v n nh hng su sc ticht lng dch v ADSL.

Chng 9:Hnh 2.3: Cu trc h thng ADSL.

2.3ADSL, ADSL2, ADSL2+

ADSL (Asymmetric DSL) Cng ngh DSL khng i xng c pht trin t khixut hin cc nhu cu truy nhp Internet tc cao, cc dch v trc tuyn, video theoyu cu...vo u nhng nm 90. ADSL cung cp tc truyn dn khng i xng ln

ADSL

Cc ngkhng phi xDSL

DSLAM

ATU-RMDF

Chuyn mchATM/IP

ChuynmchCO

POTS/ISDN

Mng bng

B chia B chiaATU-C

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ti 8 Mb/s lung xung v 16- 640 Kb/s lung ln vi khong cch truyn dn 5km vgim i khi tc ln cao. u im ni bt ca ADSL l cho php khch hng s dngng thi mt ng dy thoi cho c 2 dch v: thoi v s liu. Mt dng ADSL migi l ADSL Lite hay ADSL khng s dng b lc xut hin t u nm 1998 chyu cho ng dng truy cp Internet tc cao, k thut ny khng i hi b lc pha

thu bao nn gi thnh thit b v chi ph lp t gim i tuy nhin tc lung xungch cn 1,5 Mb/s.

ADSL2 thm nhng ci tin v iu ch v m ha lm tng hiu qu s dng bngthng.

ADSL2+ m rng bng tn cho chiu xung ti 2.2 Mhz.

1.1.6ADSL

ng dy thu bao s bt i xng ADSL l k thut truyn dn mch vng ni htng thi truyn ti trn cng mt i dy cc dch v sau:

Tc bit thu (v pha thu bao) ln ti gn 9 Mbit/s. Tc bit pht (v pha mng) ln ti 1 Mbit/s. Dch v in thoi truyn thng POTS.

H thng truyn dn c thit k hot ng trn cp ng xon i, nhiu cdy hn hp. K thut truyn ti ADSL c xy dng da trn iu kin khng c cungia cm v c mt vi trng hp hn ch ca nhnh r c chp nhn. Nhng pdng cng ngh tin tin nng cao tc truyn dn, c th cung cp cho thu baodch v bng rng mt chiu nh HDTV, dch v s liu tc trung bnh kiu trao i v

dch v in thoi thng thng.2.3.1.1K thut iu ch

Hin c 3 k thut iu ch c s dng l QAM, CAP v DMT, k thut DMT(Discrete Multi- Tone Modulation) c s dng rng ri.

iu ch DMT l k thut iu ch a sng mang. DMT chia ph tn s thnh cc

chu k k hiu. Mi chu k k hiu c th mang mt s lng bt nht nh. Ph t 26 kHz

n 1,1 MHz c chia thnh cc knh 4 kHz v DMT m ho v iu ch to thnh cc

knh ph 4 kHz. Cc bt trong mi knh ph c iu ch bng k thut QAM v t

trong cc sng mang, hnh 2.4.

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Chng 10:Hnh 2.4: ADSL s dng v khng s dng k thut trit ting vng

i vi bt k loi m ng truyn no s dng mt i dy cho vic truyn songcng u phi chia bng tn hot ng thnh bng tn t tng i ti thu bao v bng tnt thu bao ti tng i (n gin l k thut ghp knh theo tn s FDM) hoc phi sdng k thut xo ting vng. Tuy nhin, trong k thut ADSL c FDM v k thut xoting vng c th s dng kt hp ng thi iu ny l do s khng i xng ca bng

tn ADSL, cc di tn c th gi chng ln nhau nhng khng trng kht vo nhau. y lc th ring ca ADSL so vi cc k thut DSL khc.

K thut xo ting vng c mt s yu im l b nh hng ln bi tc ng caxuyn m u gn (NEXT); khi u thu c th nhn tn hiu c truyn sang t hthng bn cnh. Cc h thng bn cnh y c th l cc i dy khc hoc thm ch lngay b pht ca h thng. Nu b thu b qua ton b di tn s m u gn pht thFDM s trnh c xuyn m u gn. Tt nhin iu ny ng ngha vi vic ct b mtlng bng tn hiu dng ca hng kia. Nh vy, s dng k thut xo ting vng s lmcho hiu sut bng tn cao hn nhng chi ph cho n li phc tp v nhy cm. K thut

xo ting vng c th s dng i vi tn s thp nht nn t hiu qu cao hn.

Trong trng hp dng mt ng truyn ng thi cho c hai hng trn cngmt di tn s cn phi kim sot ting vng. Mt cch kim sot ting vng l chia tns thnh hai bng tn cho ng t tng i ti thu bao v ngc li.

2.3.1.2K thut truyn dn song cng

C 3 k thut truyn dn song cng trn i dy ng l: phn chia theo tn s(FDM), phn chia theo thi gian (TDM) v trit ting vng (EC). ADSL thng thc hink thut FDM v EC.

K thut ghp knh theo tn s.

Bngtn

ngln

Bng tnng xung

Bngtn

ngln

Bng tnng xung

0-4 kHz 25 kHz 200 kHz ~1,1 MHz 0-4 kHz 25 kHz 200 kHz ~1,1 MHz

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Chng 11:Hnh 2.5: Phn chia bng tn ca k thut FDM

K thut ny cho php di tn pht tch khi di tn thu trnh t xuyn m v cdi tn bo v gia chng.

Phng php ny c u im sau:

Trit tiu c NEXT v hai di tn s cch nhau bng bng tn bo v. Khng cn s ng b gia pht v thu. c pht trin t lu nn t c s chn mui cng ngh. Tuy nhin vn cn tn ti mt s nhc im: Khng s dng hiu qu bng thng v lung ln v xung 2 di tn khc

bit nhau v cn c di tn bo v. Tc lung xung di tn cao nn b gim nhanh chng khi c ly truyn

dn tng do suy hao min tn s cao nhanh. Vn xy ra hin tng NEXT mc d trng hp l tng cc b cp u

cng loi nhng vn c cc h thng DSL khc nhau hot ng trong cngb cp .

Fre uenc kHz

SignalPower

4 2 13 1

DownstreamData

UpstreamData

256 channelsChannelSpacing

4.3125 kHz

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K thut trit ting vng EC

K thut ny s dng mt knh duy nht cho c pht v thu nn ph tn hiu cachng trm ln nhau v tn ti ting vng ca tn hiu pht ln trong tn hiu thu nn cnmt b kh ting vng ti pha thu.

Ting vng gm t hp hai loi: ting vng u gn v u xa. Mc ch ca btrit ting vng l trit ting vng u gn cn tn hiu u xa nh hng khng ng knn c th b qua.

Mc truyn

POTS LnBo v Xung

Tn s

Chng 12:Hnh 2.6: Phn chia bng tn ca k thut EC

Nh vy, k thut ny cho php hai modem s dng ton b bng thng c sn trnc hai hng.

Pht(ln)

Thu(xung)

HybridADF

HybridADF

Pht(xung)

Thu(ln)Tn hiuhng ln

Tn hiuhng xung

Ting vng(Echo)

Chng 13:Hnh 2.7 Phn tch tn hiu ln, xung bng phng php kh ting vng

Khi tn hiu truyn qua mch sai ng (hybrid), mt phn tn hiu vng li u thudo mch hybrid khng hon ho. B lc s p ng ADF c s dng c chc nng tora mt bn sao ca tn hiu vng v ting vng b trit hon ton bng cch tr bn saony vi tn hiu vng thc t

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u im:

Tn dng hiu qu bng thng v ph hai hng trm ln nhau. Ci thin ng k tc truyn nht l khi c ly di v tn hiu hng xung

c s dng bng tn thp l vng m suy hao nh hn. Nhc im: Khng loi b c NEXT do c nhiu h thng khc nhau lm vic trong

cng b cp m b trit ting vng khng th loi b c xuyn m tchng.

Vic ch to nhng b lc s thch ng rt phc tp nht l khi lm vic vitn s cao. V vy, cc modem ADSL hin nay vn s dng kiu FDM khiyu cu tc cao cha gay gt lm.

2.3.1.3Nguyn l thu pht

Chng 14:Hnh 2.8 : S khi thu v pht ADSL

Khi to khung: Nhn cc knh d liu, EOC, AOC v cc bt ch th ri to khungv siu khung theo tc tho thun sau qu trnh khi to. S liu trn ng truyn dnADSL c b tr thnh cu trc siu khung.

CRC: To 8 bt kim tra li v t trong khung th nht ca mi siu khung. Trongmt lung, CRC s kim tra tt c cc bt chuyn qua tr cc byte FEC, CRC ca siukhung trc v khung ng b. CRC gip pht hin c bao nhiu siu khung sau khithu xut hin mt li khng th sa c bng FEC.

DataData

EOCEOC

AOCAOC

BitBit chchthth

DataData

EOCEOC

AOCAOC

BitBit chchthth

BB ttookhungkhung

CRCCRC

CRCCRC

CRCCRC

CRCCRC

TrTrnn

TrTrnn

TrTrnn

TrTrnn

MM hahaRSRS

MM hahaRSRS

MM hahaRSRS

MM hahaRSRS

anan xenxen anan xenxen SSpp xpxpvv

mm hahachch mmiimm

IIDDFFTT

IIDDFFTT

ThThmmTinTintt

vvngng

ThThmmTinTintt

vvngng

D/AD/AD/AD/A

BB gigiiikhungkhung

CRCCRC

CRCCRC

GiGiii trtrnn

GiGiii trtrnn

GiGiii mm

GiGiii mm

GiGiiianan xenxen GiGiii

mmgigiiissppxpxp

FFDDQQ

DDFFTT

TTchchtintintt

vvngng

TDQTDQ

ADC+ADC+fillterfillter

BB gigiiikhungkhung

CRCCRC

CRCCRC

GiGiii trtrnn

GiGiii trtrnn

GiGiii mm

GiGiii mm

GiGiiianan xenxen GiGiii

mmgigiiissppxpxp

FFDDQQ

DDFFTT

TTchchtintintt

vvngng

TDQTDQ

ADC+ADC+fillterfillter

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Khi trn (Ngu nhin ho): Thc hin trn lung nhanh v lung chm mt cchc lp nhm mc ch trnh cc cc bt ging nhau xut hin lin tip. Ti u thu qutrnh din ra ngc li vi cng qui lut.

Khi FEC: Thm bt d vo phn d liu nhm sa mt s bt b li sau b giiiu ch pha thu ( y s dng m Reed Solomon).

Khi an xen: Ch tn ti trong lung xen, phn tn li cm ti cc t m khcnhau sao cho s byte b li lin tip nm trong kh nng sa li ca loi m . Tt nhin,lc ny thng tin s b tr hn so vi khng an xen.

Sp xp tone: L qu trnh tch mt s bt nht nh ri gn vo mt tone nhtnh. Sau qu trnh khi to, s lng bt gn cho mi tone c quyt nh (c gi trt 0 n 15 bt). D liu t hai ngun nhanh, chm c a vo sp xp tone trc khia n b m ho DMT.

M ho: Sau khi sp xp tone, mi bin phi thc hin m ho cc bt ny. Ngoi ra,

khi m ho cn c chc nng iu chnh li knh (Cng sut) cho tng bin nh bnggi tr bit/tone v li bin.

Khi IDFT: Sau khi sp xp tonev m ho s to ra mt s phc. Nh vy, s cnhiu nht l 256 s phc. Khi IDFT s chuyn cc s phc trong min tn s ny sangtn hiu trong min thi gian.

Khi thm tin t vng: to ra knh gi tun hon gip qu trnh cn bng trongmin tn s pha thu thun li hn.

Khi bin i s-tng t DAC v lc dng: Chuyn i cc mc tn hiu sang

mc in p v pha khc nhau trn ng truyn. B lc gii hn tn hiu pht trongbng thng ca ADSL ..

1.1.7ADSL2

2.3.1.4Gii thiu chung

ADSL2 l th th hai ca ADSL c chun ho trong ITU G.992.3 v G992.4da trn chun ca th h th nht ITU G.992.1 v G.992.2. Tuy nhin ADSL2 c nhiuci tin so vi ADSL th h th nht. Nh nhng ci tin nu trn m ADSL2 ci thinng k v tc v khong cch so vi ADSL. Vi ADSL2 c th t c tc

ng xung trn 8Mbps v ng ln ti 800Kbps trn mt i dy in thoi. So viADSL, ADSL2 tng tc ng xung khong t 50 n 196Kbps v tng tc ng ln khong t 32 n 64Kbps. Mt khc, vi cng tc s liu nh ADSL,ADSL2 tng khong cch so vi ADSL t 500 n 1000feet (khong t 150 n 300m).Hnh 3.29 m t mt v d v tc v khong cch ADSL2 so vi ADSL th h thnht. Trn ng y in thoi c cng di so vi ADSL th ADSL2 c tc s liu

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tng khong 50Kbps. Vi cng tc nh ADSL, ADSL2 t c khong cch tngkhong 600feet (khong 180m) so vi ADSL, iu ny lm tng vng ph khong 6%.

C c kt qu ny l do ADSL2 ci thin hiu qu iu ch, gim tiu khung,t c li m ho cao hn, ci thin trng thi khi to v tng cng thut ton xl tn hiu... So vi ADSL, ADSL2 b xung mt s tnh nng mi, l nhng tnh nng

lin quan n Cc tnh nng lin quan n ng dng, cc tnh nng lin quan n PMS-TC v cc tnh nng lin quan n PMD.

2.3.1.5Cc tnh nng lin quan n ng dng

H tr ng dng ch hon ton s

ADSL a ra mt ch tu chn cho php truyn s liu ADSL trn bng tnthoi do tng thm 256Kbps cho tc d liu ng ln. Ch ny l la chn hpdn i vi cc doanh nghip s dng dch v thoi v s liu trn cc ng dy ring

bit bi v nh ch ny m cc doanh nghip t c cc dch v vi tc ngln cao hn.

H tr ng dng thoi trn bng tn ADSL

C ba phng thc c bn truyn lu lng thoi trn ng dy cp ng sdng bng tn DSL l: Thoi qua ch truyn dn cn ng b (VoATM), thoi quagiao thc internet (VoIP) v thoi phn knh trn DSL (CVoDSL).

Phng thc VoATM, thc hin vic sp xp thoi c s ho v thng tinbo hiu vo cc t bo ATM, cc t bo ny c truyn trn ng dy in thoi v

truyn qua mng n kt ni ring o ATM.Tng t phng thc th hai, VoIP cng sp xp thoi c s ho v thng

tin bo hiu vo cc gi IP v truyn chng trn ng dy in thoi cng vi s liukhc.

Cn phng thc CVoDSL, l mt ci tin ca cng ngh ng dy thu bao s.Phng thc ny truyn lu lng thoi TDM mt cch trong sut qua bng tn DSL.CVoDSL l duy nht gia cc gii php thoi qua DSL trong n truyn thoi trong lpvt l, cho php truyn cc knh thoi trn bng tn DSL trong khi vn duy tr c POTS

v truy nhp Internet tc cao. y l mt phng thc n gin, linh hot, hiu qu vmt chi ph cho php thit b th h sau c chc nng thoi.

H tr chc nng ghp ngc ATM (IMA) trong ATM TPS-TC:

Tc s liu ti khch hng c th tng ng k bng cch ghp nhiu ngin thoi cng nhau. thc hin vic ghp, chun ADSL2 h tr chc nng ghpngc ATM (IMA) c trin khai cho cu trc ATM truyn thng. Thng qua IMA,ADSL2 c th ghp hai hoc nhiu i dy ng trong mt tuyn ADSL. Kt qu l t

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c tc ng xung linh hot hn c th l : 20 Mbps trn 2 i ghp, 30 Mbps trn3 i ghp, 40 Mbps trn 4 i ghp.

2.3.1.6Cc tnh nng lin quan n PMS-TC

Vic phn khung linh hot hn, h tr ti 4 khung mang, 4 ng:

S liu c truyn khc nhau c th c tp hp vo cc cu trc khc nhau khichng truyn qua chc nng PMS-TC pht. Nhm cu trc ny c gi l cu trckhung.

Gim tiu khung

H thng ADSL2 gim tiu khung bng cch s dng khung vi cc tiu cakhung c th lp trnh c. Do , khng nh trong chun ADSL th h th nht s bittiu trn khung l c nh v chim 32Kbps ca ti s liu thc t, trong chun.ADSL2 s bit tiu chun trong khung c th lp trnh c chim t 4 n 32Kbp. Trong

cc h thng ADSL th h th nht, trn cc ng dy in thoi c tc s liu thp(v d 128Kbps) th 32Kbps (hoc 25% tc s liu tng) c cung cp pht c nhcho thng tin tiu . Trong cc h thng ADSL2, tc s liu tiu c th gimxung cn 4Kbps, do cung cp thm 28Kbps cho ti s liu.

2.3.1.7Cc tnh nng lin quan n PMD

Chun on

Vic xc nh nguyn nhn ca nhng vn pht sinh trong qu trnh cung cpdch v ADSL cho khch hng l mt tr ngi rt ln trong tin trnh pht trin caADSL. khc phc vn ny, b thu pht ADSL2 c tng cng kh nng chunon. Kh nng chun on cung cp cc cng c gii quyt nhng vng mc trongv sau khi to, gim st trong khi cung cp dch v v nng cao nng lc. chunon v gii quyt cc vn gp phi th cc b thu pht ADSL2 cung cp kh nng thchin o tp m ng dy, suy gim mch vng v t s tn hiu trn tp m (SNR) ti haiu ng dy. Kt qu ca nhng php o ny c tp hp li bng cch s dng ch kim tra chun on c bit ngay c khi cht lng ng dy l qu ti c thhon thnh kt ni ADSL.

Ngoi ra, ADSL2 bao gm kh nng gim st hiu nng thi gian thc, kh nngny cung cp thng tin v cht lng ng dy v iu kin tp m ti hai u ngdy. Thng tin ny c x l bi phn mn gim st cht lng kt ni ADSL vtrnh xy ra cc li dch v trong tng lai. Thng tin ny cng c s dng quytnh xem mt khch hng c th c cung cp cc dch v c tc s liu cao hn haykhng.

Thch ng tc

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Cc ng dy in thoi c bn vi nhau trong b cp nhiu i cha 25 hocnhiu hn cc i dy xon. Kt qu l tn hiu in t mt i gy ra t trng trn cci gn k trong b cp. Hin tng ny c gi l xuyn m v c th cn tr ctnh tc s liu ADSL. Kt qu l nhng thay i ca cc mc xuyn m c th lmt kt ni trong ADSL. Xuyn m ch l mt nguyn nhn gy t kt ni trn h thng

ADSL. Cc nguyn nhn khc c th l do nhiu sng v tuyn AM, nhng thay i vnhit v nc trong b cp.

ADSL2 gi quyt vn ny bng cch thch ng lin tc tc s liu theo thigian thc. Ci tin ny, c gi l thch ng tc lin tc (SRA), cho php h thngADSL2 thay i tc ca kt ni trong khi cung cp dch v m khng lm ngt dch vhoc gy li bit. ADSL2 pht hin ra nhng thay i trong iu kin knh (v d, mttrm v tuyn AM ni ht ngng pht vo bui ti) v thch ng tc s liu vi iukin mi trong sut vi ngi s dng.

Khi to nhanhKhi to b thu pht ADSL c yu cu cho kt ni gia ATU-C v ATU-R

thit lp mt tuyn thng tin gia chng. ADSL th h th nht ch h tr ch khito thng thng. Tuy nhin ADSL2 h tr c hai ch : ch khi to thng thngv ch khi to nhanh. Th tc khi to thng thng mt khong t 10 ti 15 giytrong khi th tc khi to nhanh ch mt khong t 2 ti 3 giy. C c iu ny l doth tc khi to nhanh da vo vic lu tr v s dng li cc tham s truyn dn t khito thng thng trc nh gim ng k thi gian iu khin.

Ci thin v mt cng sut:

Cc b thu pht ADSL th h th nht hot ng ch cng sut ln nht sutngy m ngay c khi khng c s dng. p ng vn ny, chun ADSL2 a rach qun l cng sut gip gim cng sut tiu th trong khi vn duy tr chc nnglun lun kt ni ca ADSL cho ngi s dng. Nhng ch ny bao gm: ch cng sut L2 v ch cng sut L3.

Ch cng sut L2 cho php tit kim ng k cng sut ti khi thu pht ADSL trm trung tm (ATU-C) bng cch vo v ra ch cng sut thp mt cch nhanh

chng da trn lu lng Internet chy trn kt ni ADSL. Ch cng sut L2 l mttrong nhng ci tin quan trng nht ca chun ADSL2. Khi ti xung cc file d liu lnth ADSL2 hot ng ch cng sut ln nht (c gi l ch cng sut L0) cc i tc ti xung. Khi lu lng Internet gim, v d nh khi ngi s dng angc mt trang vn bn di, th cc h thng ADSL2 c th chuyn sang ch cng sutthp L2, trong ch ny tc s liu gim ng k v gim cng sut tiu th.

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1.1.8ADSL2+

2.3.1.8Gii thiu chung

Cng ngh ADSL2+ l thnh vin mi nht trong h cc chun ADSL. ADSL2+c chun ho trong ITU G.992.5 vo thng 5 nm 2003. C th coi ADSL2+ l ADSLth h th ba hoc l phin bn delta ca ADSL th h th hai (ADSL2). Cng ging nh

ADSL2, ADSL2+ s dng i dy ng xon truyn ng thi thoi v s liu tc cao gia kt cui mng (ATU-C) v kt cui khch hng (ATU-R). Tuy nhin bng tnca ADSL2+ c khc so vi bng tn ca ADSL2. Trong khi ADSL2 s dng bng tn t0-1,1Mhz th ADSL2+ s dng bng tn t 0-2,2Mhz. Cng ging nh ADSL2, ADSL2+dnh bng tn c s truyn thoi, bng tn thp truyn s liu ng ln v bng tncao truyn s liu ng xung. Tuy nhin, bng tn ng xung ca ADSL2+ gpi so vi bng tn ng xung ca ADSL2, do ADSL2+ tng ng k tc s liutrn ng dy in thoi c khong cch ngn hn 9Kilofeet (khong 3 km)

Nh c tnh nng mi thm vo m ADSL2+ c th t c tc s liu ngxung ti 25Mbps. Trn ng dy in thoi c khong cch 3Kilfeet (khong gn 1km) tc s liu ng xung c th t c 24Mbps v c th t c 20Mbps trnng dy c khong cch 5Kilfeet (khong 1.5 km).

ADSL2+ l ADSL2 vi bng tn m rng n c chun ho da trn chun caADSL2. Do , ADSL2+ mang y cc c tnh ca ADSL2. Tuy nhin, ADSL2+cn c thm mt s tnh nng mi nhm p ng tc s liu cao hn trn mch vngc khong cch ngn hn. Mt s tnh nng mi c thm vo nh: m rng bng tn,ghp t tc cao hn v mt s tnh nng khc ca ADSL2+.

2.3.1.9M rng bng tn

Trong khi hai thnh vin trong h cc chun ADSL2 l G.992.3(G.dmt.bis) vG.992.4(G.lite.bis) s dng bng tn ng xung ti 1,1Mhz v 552Mhz tng ng thADSL2+ s dng bng tn ng xung ti 2.208Mhz tng ng vi 512 sng mang ph(Hnh 3.30). Nh vy bng tn ca ADSL2+ tng gp i so vi bng tn ng xungca ADSL2 cn bng tn ng ln ca ADSL2+ khng thay i so vi ADSL2

Nh ci tin c bit ny m tc s liu ng xung ca ADSL2+ tng gp i

so vi ADSL2 trn ng dy in thoi c khong cch di 4Kilofeet v cao hn nhiuso vi ADSL2 trn ng dy in thoi c khong cch t 4 n 8Kilofeet. Tuy nhinvi ng dy in thoi c khong cch ln hn 8Kilofeet th tc s liu ngxung ca ADSL2+ tng t nh ADSL2 (Hnh 2.9).

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Chng 15:Hnh 2.9: Tc s liu ng xung ca ADSL2+ so vi ADSL2

Vi mc ch gim xuyn m th ADSL2+ cung cp kh nng ch s dng cc tns nm trong khong t 1.1Mhz ti 2.2Mhz bng cch che cc tn s thp hn 1.1Mhz.iu ny c bit hu dng khi cc dch v ADSL t trm trung tm (CO) v t kt cuiu xa (RT) cng nm trn mt cp ti nh khch hng. Trong iu kin ny, nh cungcp dch v c th trin khai dch v ADSL2 vi bng tn ng xung t 0.14Mhz ti1.1Mhz cho khch hng cch xa trm trung tm (CO) vi yu cu tc s liu khngthc s cao cn cc khch hng cch xa trm trung tm (CO) nhng gn trm kt cuiu xa (RT) vi yu cu tc s liu cao th c th s dng dch v ADSL2+ vi bngtn ng xung t 1.1Mhz ti 2.2Mhz. Bng cch ny c th loi b hu ht xuyn mgia cc dch v v m bo c tc ng dy t trm trung tm.

2.3.1.10Ghp t tc cao hn

K thut ghp nhiu ng dy in thoi nhm mc ch t tc s liu caohn v ci thin khong cch l k thut mi ca h cng ngh ADSL2. Cng ging nhADSL2, vic ghp ADSL2+ cng thc hin ghp nhiu ng ADSL2+. Tuy nhin,

ADSL2+, vic ghp t c tc s liu cao hn rt nhiu so vi ADSL2. Nh ch ratrn Hnh 3.33, bng cch ghp hai ng ADSL2+ c th cung cp cho khch hng tc s liu ln n 44Mbps trn ng dy c khong cch ngn hn 5Kilofeet (khong1.5km). Trn cc ng dy in thoi c khong cch xa hn, vic ghp hai ngADSL2+ c th h tr c tc 8Mbps vi khong cch trn 12Kilofeet (khong3.6km).

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Chng 16:Hnh 2.10: Ghp hai ng ADSL2+

Vic ghp nhiu i dy in thoi trong ADSL2+ c mt s c im nh sau:

Vic ghp h tr kh nng t ng gii phng v khi phc cc i dy mkhng vn s can thip ca con ngi. Mt khc, vic ghp c th cthc hin t ng bng phn mm.

Vic ghp h tr cc tc s liu khc nhau (vi t l 4/1) gia cc i

dy. iu ny rt c ngha trong trng hp cc ng dy ng c dunglng thp hn cc ng dy khc th khng cn thit phi gim tc sliu trn cc ng dy c dung lng cao hn.

C th ghp ti 32 i dy. Cc cng (port) trn card ng dy ADSL2+ c ghp mt cch ngu

nhin. Ngha l vic ghp c thc hin bng cch kt hp bt k cng nov vic ghp rt mm do.

Chun ghp ATM c s dng trn bt k lp vt l no. Ngoi ADSL2+,n c th c s dng cho cc dch v DSL khc.

2.3.1.11Mt s tnh nng khc ca ADSL2+Ngoi cc tnh nng mi c trnh by trn, ADSL2+ cn c thm mt s tnh

nng mi nh sau:

ADSL2+ c kh nng h tr ti 3 t m (Reed-Solomontrene) k hiu,trong khi ADSL2 ch c th h tr ti a 2 t m (Reed-Solomontrene)trn k hiu. Gi tr ny c quy nh khc nhau trong chun ITU G.992.3v G.992.5. C th l G.992.3 quy nh s khung ghp s liu trn k t v

0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15

Bonded ADSL2+ADSL2+

ADSL

LOOP LENGTH (KFT)

D

ATARATE

(MBPS)

5045403530252015105

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s t m FEC trn k hiu cc i l 2. Trong khi , G.992.5 quy nh skhung ghp s liu trn k hiu v s t m trn k hiu cc i l 3.

Di s iu khin ca ngi vn hnh thng qua CO-MIB, vic iu khinph ng xung vi PSD pht cc i ti im tham chiu U-C trn sngmang ph cho php vic cu hnh theo yu cu ca tng vng (v d, BcM, Chu u hoc Nht Bn) v cu hnh theo cc mi trng trin khai (v

d, trm trung tm (CO) hoc trm u xa (RT)). Vic nh dng ph ng xung trong thi gian showtime (dng PSD pht

trong bng thng l khng phng) ci thin linh hot ca PSD pht ngxung.

2.4HDSL, HDSL2,SHDSL, HDSL4

1.1.9HDSL

2.4.1.1HDSL nguyn bn

Khi nim ban u v HDSL (ng dy thu bao s tc cao) xut hin vo

nm 1986 phng th nghim AT&T Bell v Bellcore. Cc thit k thit b thu phtHDSL thc cht l thit k ISDN c bn mc cao hn. H thng HDSL mu xut hinnm 1989. Thit b HDSL u tin c Bell Canada a vo hot ng vo nm 1992 docng ty Tellabs Operation Inc sn xut. Nm 1997 trn th gii c khong 450000ng dy HDSL ang hot ng trong c khong 250000 ng dy HDSL BcM. Mi nm c hn 150000 ng dy HDSL c lp t. Thng 10 nm 1998, ITUthng qua khuyn ngh G.991.1 cho HDSL th h th nht, tiu chun ny da trn tiuchun ETSI TM-03036. ITU bt u nghin cu xy dng khuyn ngh HDSL th h th2 (HDSL2) gi l G.991.2.

HDSL c a dng hn T1 truyn thng l bi v HDSL cung cp cc c tnhchun on (bao gm o SNR) v HDSL gy xuyn m t hn cc h thng truyn dnkhc do tn hiu truyn c hn ch trong bng tn hp hn T1 truyn thng.

2.4.1.2Kh nng v ng dng HDSL

HDSL truyn ti hai hng 1,544Mbit/s hoc 2,048 Mbit/s trn ng dy inthoi di n 3,7 km (12 kft) vi dy 0,5 mm (24 AWG) i dy xon khng c b lptrung gian v c th tng chiu di ln gp i vi 1 b lp trung gian. Hn 95% ngdy HDSL khng c b lp. HDSL l phng thc truyn dn tin cy cho tt c cc vngphc v vi t l li bt l 10-9 n 10-10. H thng HDSL DS1 (1,544 Mb/s) s dng haii dy, mi i dy truyn 768 kbit/s ti hiu dng (784 kbit/s tnh) trn mi hng. Do thut ng song cng c s dng m t h thng truyn dn HDSL. H thngHDSL E1 (2048 kbit/s) c th la chn s dng hai hoc 3 i dy, mi i dy s dnghon ton song cng. HDSL 2,048 Mbit/s 3 i dy s dng b thu pht rt ging b thupht h thng 1,544 Mbit/s. Mch vng HDSL 2,048 Mbit/s c th c mch r nhngkhng c cun cn bng.

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Mc d ban u HDSL c m t l cng ngh cn lp, nhng cc b lp HDSLvn thng c s dng trn ng dy HDSL khng b lp c chiu di t 2,75 kmn 3,7 km (9 n 12 kft). i vi dy 24 AWG, c th t c 7,3 km khi s dng mtb lp v 11 km (36 kft) khi dng 2 b lp. di thc s c th thp hn nhng nikhng th t c b lp chnh xc v tr trung gian. Ban u h thng HDSL hai b

lp c cp ngun bng cch, b lp th nht c cp qua ng dy t CO, b lp thhai c cp ngun t pha thu bao. Vic cp ngun t pha thu bao c hn ch v qunl v bo dng. Do ngun tiu th t cc b thu pht ngy nay l nh nn ngi ta c thcp ngun cho c hai b lp t ngun ca CO.

2.4.1.3Truyn dn HDSL

C mt vi gii php c la chn cho h thng HDSL nguyn thu: song cngn, n cng kp v song cng kp.

Song cng n ch cn s dng mt i dy v mt cp thit b thu pht mi u

ca ng dy. Hai hng truyn dn c th c tch bit bng ghp knh theo tn s(FDM) hoc bng truyn dn hn hp trit ting vng. Tuy nhin, truyn ton b ti trnhu ht cc mch vng u da trn cng ngh u nhng nm 90. Hn na di thng lncn phi quan tm n tng thch ph vi cc h thng truyn dn khc. H thng HDSL1,544 Mbit/s i dy n (i khi gi gi l SDSL) pht trin vo u nhng nm 90 c di mch vng t hn 6 kft trn i dy 26 AWG; do c khong ngn ny hn chrt ln kh nng s dng ca n. Ch vi k thut tin tin xut hin vo cui nm 90 thtruyn dn 1,544 Mbit/s n song cng mi tr thnh hin thc. HDSL2, m t phn

2.4.4, p dng truyn dn song cng n.Truyn dn n cng kp s dng hai i dy, vi mt i dy truyn ton b titheo mt hng v i dy th hai truyn ton b ti theo hng ngc li. Phng phpny rt n gin tch tn hiu hai hng khc nhau ca truyn dn. Khai thc T1truyn thng s dng truyn dn n cng kp. Truyn dn n cng kp c nhc imtruyn tn hiu c bng tn ln do c suy hao ln v xuyn m tn s cao. Do cxuyn m cc tn hiu truyn trn hai i dy khng hon ton tch bit. Do cc thitb thu pht n cng kp c th n gin hn nhng hot ng km hn song cng kp.

Truyn dn song cng kp ci tin di mch vng v tng thch ph bngcch gi mt na thng tin trn mi i dy. HDSL gim bng tn ca tn hiu truynbng cch s dng truyn dn ECH truyn hai hng cng mt bng tn. Nng lngtn hiu truyn ca HDSL song cng kp gim dn i vi tn s ln hn 196 kHz. Ktqu l tn hiu xuyn m v suy hao gim. Mt u im khc ca truyn dn song cngkp l s dng mt i dy c th d dng cung cp h thng truyn dn na tc .

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1.1.10HDSL th h th hai (HDSL2)

Tiu chun cho cng ngh HDSL th h th hai xut hin vo nm 1995 c tc bit v di mch vng ging nh HDSL th h th nht ch khc l s dng mt i dythay v hai i dy. Gim s lng i dy l rt quan trng bi v rt nhiu LECs thiucc i dy d mt s vng. HDSL2 c k thut m ho cao v iu ch phc tp hn.

La chn k cng tn s pht v thu cho HDSL2 chng li xuyn m. Cc phin bnmi ca HDSL mn nhiu tng t ADSL. Phin bn tng thch tc dng nh xut hin. Ngi ta ang xem xt t bng tn s cho HDSL ln trn bng tn thoitng t hoc trn ISDN c bn. Thut ng SDSL (DSL i xng hay DSL i dy n)cng c s dng m t cc phin bn sau ca HDSL.

1.1.11SHDSL

SHDSL l cng ngh kt hp ca HDSL 2 v SDSL vi tc thay i t 192kbpsn 2,134 Mbps, khong cch tng ng vi tc ti a l 2km. Trong thc t, n c

th cu hnh dng 2 i dy cung cp tc t 384kbps n 4,264Mbps.1.1.12HDSL4

S dng 4 i dy truyn tc nh trong HDSL2 do vy n c th gimbng tn s dng, ko di c ly truyn dn, gim s lng trm lp, do vy n c th tc c li l 11kf thay v 9 kf nh HDSL2, ng thi n cng lm gim tc ng nhinn cc h thng khc.

2.5 VDSL v VDSL2

1.1.13VDSL

L mt cng ngh trong h xDSL VDSL (Very high data rate DSL) cung cp ccng thu bao s vi tc rt cao. Cng nh cc dch v khc trong h xDSL nhADSL, HDSL, SDSL k thut VDSL c s dng cung cp cc dch v bng rngnh cc knh tivi, truy nhp d liu vi tc rt cao hi ngh qua video, video ng,truyn t hp d liu v tn hiu video trn cng mt ng dy cho cc thu bao dnc v kinh doanh trong lc cha lp t c mng cp quang n tn nh thu bao. Hnh2.11 m t cc kh nng cung cp dch v ca k thut VDSL.

K thut VDSL s dng phng thc truyn dn ging nh ADSL nhng k thut

VDSL c kh nng cung cp s liu vi tc rt cao gn gp 10 ln tc truyn dnca ADSL , Hnh 2.11. Tc truyn dn ca VDSL lung xung t ti 52 Mb/s trongchiu di khong 300m, v lung xung t tc thp 1,5 Mb/s vi chiu di cp3,6km. Tc lung ln trong ch khng i xng (l phng thc m tc truyndn t pha tng i ti thu bao bng tc truyn dn t thu bao ti tng i) l 1,6-2,3 Mb/s. Tc lung trong ch i xng l 26 Mbps. Phng thc truyn dn khng

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i xng rt ph hp cung cp dch v tc cao t pha tng i ti thu bao nn rthay c s dng trong k thut VDSL.

Trong VDSL c hai knh s liu u hot ng tn s cao hn tn s s dng chothoi v ISDL nn cho php cung cp cc dch v VDSL bn cnh cc dch v ang tnti.

Khi cn tng tc lung xung hoc ch i xng th h thng VDSL s dngk thut trit ting vng.

Cng ngh VDSL c ng dng trong truy cp dch v bng rng nh dch vInternet tc cao, cc chng trnh Video theo yu cu.

Ngoi vic c kh nng cung cp tc cao hn nhiu so vi tc truyn dnca k thut ADSL k thut VDSL cn yu cu khong ng nh hn k thut ADSL nnk thut truyn dn ca VDSL khng phc tp bng k thut truyn dn ADSL. Mc d cnhiu u im nh vy nhng k thut ny vn cha c s dng rng ri l v cha

la chn c c ch iu ch, bng tn, phng php ghp knh thch hp. Hn na,mt s chipset ca modem s dng k thut VDSL vn cn t nn k thut ny cha cs dng nhiu trong thc t. Tuy nhin y l mt k thut ha hn trong mt vi nm tiptheo.

Chng 17:Hnh 2.11: Kh nng cung cp dch v ca k thut VDSL

Trong ngha l bc m tin ti mng truy nhp quang (APON, BPON,GPON), VDSL c s dng trong cc mch vng ni ht truyn tn hiu t khimng quang ONU ti cc thu bao. Bng 2.2 m t tc v khong cch t ONU tithu bao.

Chng 18:Bng 2.2: Tc khong cch cc loi VDSL

Tc thu (Mbit/s) Tc pht (Mbit/s) Khong cch (met)

STMChuyn mch gi

ATMATM

STMChuyn mch gi

Ton b ATM

Dchv ONU

VDSLHUB

TECp quangMng vng

Cp ngVDSL

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52 6,4 1000- 30026 3,2 2500- 80026 26 1000- 30013 13 1800- 60013 26 3750- 1200

1.1.14VDSL2L cng ngh mi nht trong h xDSL n c th cung cp tc ln ti 250Mb

50761116 3338397 cong ngh truy nhp trong mng ngn

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