Nghiên cứu công nghệ và ứng dụng điều chế trong ADSL

1
MỤC LỤC
 3
 8
 10
 12
 12
 13
 14
1.3.1 Tr 14
1.3.2  15
1.3.3  15
 16
 18
 18
 19
2.2.1 QAM 19
 19
 21
2.2.1.3  22
2.2.2  23
2.2.3  25
 29
2.3.1 Mã hoá Reed- Solomon (RS) 29
 30
 32
 33
 34
 36

 37


2
 40
 40
 42
 45
 45
át 46
 49
 52
 53
 53
 62
 62
 62
 62
 62
 62
 chòm sao 64
 65
 66
 66
3.5.10  67
 67
 67
 71
L 72
 76

4.1  76
4.2 Mã Matlab  76
 85


3
THUẬT NGỮ VIẾT TẮT

A
AAL
ATM Adaptation Layer

ADC
Analog Digital Conversion

ADF
Adaptive filter

ADSL
Asymetric Digital Subscriber
Line

AEX
AS extra byte

ANSI
American National Standard
Institute

ATM

Asynchronous Transfer Mode

ATU
ADSL Tranceiver Unit

ATU-C
ATU-CO

ATU-R
ATU-Remote

B


BRAS
Broadband Remote Access
Server

DSLAM
BER
Bit Error Ratio

C


CAP
Carrierless Amplitude Phase

sóng mang
CATV

Cable Television

CBR
Constant Bit Rate

CO
Central Offices

CPE
Customer Premises
Equipment



4
D


DAC
Digital Analog Conversion

DLC
Digital Loop Carrier

DMT
Discrete Multitone

DSL
Digital Subscriber Line


DSLAM
DSL Access Module

DASC
Digital Access an Cross
Connect
 

E


EC
Echo Canceller

ETSI
European Telecoms Standard
Institute

F


FE
Fast Ethernet


FDD
Frequency Division Duplex


FDM

Frequency Division
Multiplexing

FEC
Foword Error Correction

FEXT
Far End Crosstalk

FSK
Frequency Shift Key

FTTB
Fiber To The Building

FTTCa
Fiber To The Carbinet

FTTC
Fiber To The Curb

FTTH
Fiber To The Home

FTTO
Fiber To The Office

FTTEx
Fiber To The Exchange


G




5
GE
Giga Ethernet


H


HDSL
High-bit rate DSL

HDTV
High Definition Television

HFC
Hybrid Fiber Coax
- cáp quang
HPF
High Pass Filter

I


IP
Internet Protocol


IDSL
ISDN DSL



ISDN
Intergrated Service Digital
Network

IP
InterSymbol Inference

ISP
Internet Service Provider

ITU
International Telecoms Union

L


LAN
Local Area Network
 
LMDS
Local Multipoint Distribution
System



LEX
LS extra byte

LPF
Low Pass Filter

M


MDF
Main Distribution Frame

MDSL
Medium DSL

MMDS
Multichannel Multipoint
Distribution System

MPEG
Motion Picture Expert Group



6
N


NEXT
Near End Crosstalk


NID
Network Interface Device

NSP
Network Service Provider

P


PSD
Power Spectral Density

PSTN
Public Switch Telephone
Network


Q


QAM
Quarature Amplitude
Modulation

QoS
Quality of Service

QPSK
Quadrature Phase Shift Key


S


SDH
Synchonous Digital Hierachy

SDSL
Single pair DSL

SOHO
Small Office Home Office

SNR
Signal Noise Ratio

T


TDD
Time Division Duplexed


TDM
Time Division Mutiplexing




V

VBR
Variable Bit Rate

VDSL
Very high speed DSL

VoD
Video on Demand

VoDSL
Voice over DSL

VDC




7
Communication
VNPT
 and Telecoms

Nam
W


WLL
Wireless Local Loop


X


xDSL
x Digital Suscriber Line



8
DANH MỤC HÌNH VẼ
 12
Hình 1.2 M 13
- 20
 20
 21
 23
 24
 24
 25
 28
 30
 31
Hình 2.11  31
 32
 33
 33
 34
 35
 35

 37
 39
 40
 41
Hì 41
 42
Hình 2.24 Song công theo nguyên lý EC 43
 44
 45


9
hát ADSL 47
 53
 53
 54
 55
 57
 57
 59
 63
 65
  72
 72
 73
 80
 80
 81
Hình  81
 82

 82
 83


10
LỜI NÓI ĐẦU

Internet ng
        

 
















tên là "Nghiên cứu công nghệ và ứng dụng điều chế trong ADSL"
 ng:




Chng 4: Chng trình mô phng h thng DMT


11

không 
.

5

-  - 


Chương 1 Tổng quan về mạng viễn thông ngày nay

12
CHƢƠNG 1 TỔNG QUAN VỀ MẠNG VIỄN THÔNG NGÀY NAY
1.1 Hiện trạng mạng viễn thông.





 


 






C

MDF

DLC
CO
Telephone

Telephone

Computer

Computer

Inter-CO
Network




CO
CO



DLC

Hình 1.1 Mô hình mạng viễn thông hiện đại
Chương 1 Tổng quan về mạng viễn thông ngày nay

13


-CO







 

- 
1.2 Hạn chế của mạch vòng đƣờng dây thuê bao













N


- 



-MDF
Hình 1.2: Mạch vòng đường dây thuê bao
Vòng dây thuê bao
Chương 1 Tổng quan về mạng viễn thông ngày nay

14

                 
Internet, .



1.3 Nhu cầu và các phƣơng pháp truy nhập băng rộng






 

âm thanh





 
.
1.3.1 Truy nhập bằng sợi quang




             

Chương 1 Tổng quan về mạng viễn thông ngày nay

15


tr

1.3.2 Truy nhập bằng vô tuyến





 

   



            




gi


 


1.3.3 Truy nhập bằng cáp đồng trục


Chương 1 Tổng quan về mạng viễn thông ngày nay

16
          
  

50 Mhz cho





1.3.4 Truy nhập bằng xDSL


D




 


,

    

      Bell Labs Techical Jurnal, 2 (2),
Spring, 1997, trang 42-

 
 



-  

Chương 1 Tổng quan về mạng viễn thông ngày nay

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- 
 
- 


               








 





Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

18
CHƢƠNG 2 CÁC KỸ THUẬT SỬ DỤNG TRONG CÔNG NGHỆ ADSL
2.1 Sự ra đời của chuẩn hoá ADSL


 

  

TU và
          

                
modem ADSL không ho





                
              



 G.992.1 (G.dmt)- 
.
 G.992.2 (G.lite)-        
.
 G.994.1 (G.hs)-.
 G.996.1 (G.test)- .
Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

19
 G.997.1 (G.ploam)-
lý cho modem xDSL.


9 
tt c các xã ph 
2.2 Các phƣơng pháp điều chế


 






                 


2.2.1 QAM
2.2.1.1 Nguyên lý điều chế





Tín 


 
Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

20
  

 

  
máy thu.



ra

các bit






trên chòm sao

sóng Sin

sóng
Cosin
Hình 2.2 Sơ đồ bộ điều chế QAM




c Sin



Hình 2.1 Sơ đồ minh hoạ phương pháp điều chế QAM-16 trạng thái

Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

21



0)/2sin()./2cos(
0




dt
(2.1)
Trong bi
.


)sin()cos()( wtYwtXtV
iia

(2.2)

2.2 1.2 Giải điều chế
2.2 và hình 2.3

ng:
 
 


.
Hình 2.3 Sơ đồ bộ giải điều chế QAM

phân


sóng
Cosin


sóng Sin

phân






B
A
C
D
E
Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

22

V
B
(t) = X
i
cos
2
(wt) + Y
i
sin(wt)cos(wt) (2.3)


V
C
(t) = X
i
sin(wt)cos(wt) + Y
i
sin
2
(wt) (2.4)


DB
τ
o
V (t)= V (t)dt





0
2
))cos()sin()(cos( dtwtwtYwtX
ii





00

2
)cos()sin()(cos dtwtwtYdtwtX
ii


ττ
( ) 0
22
ii
D
XX
Vt  



EC
τ
o
V (t)= V (t)dt


τ
2
cos( )sin( ) sin ( )ii
o
X wt wt Y wt dt



ττ

2
cos( )sin( ) sin ( )ii
oo
X wt wt dt Y wt dt



τY τY
( ) 0
22
ii
EVt  








  

 
2.2.1.3 Một số đặc điểm của phương pháp điều chế QAM
a) Ưu điểm: 
 

Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

23

b) Nhược điểm:


-7



Bảng 2 1 SNR cần thiết cho các điều chế QAM
   



 
2.2.2 Điều chế pha và biên độ không có sóng mang CAP

QAM
SNR (dB)
4
QAM 16
21.8
6
QAM 64
27.8
8
QAM 256
33.8
9
QAM 512
36.8
10

QAM 1024
39.8
12
QAM 4096
45.8
14
QAM 16384
51.8
SNR(dB)
10
-10

BER
10
-7


QAM-64
QAM-32
QAM-16
QAM-4
Hình 2.4 Ảnh hưởng của số trạng thái đến SNR trong QAM
21,8
27,8
Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

24
               








   

 









Hình 2.6 Bộ giải điều chế CAP









các bit

vào

Tìm
(x,y)
h^(t)
h(t)



Hình 2.5 Sơ đồ khối bộ điều chế CAP






A/D



Chương 2 Các kỹ thuật sử dụng trong công nghệ ADSL

25

                 

2.2.3 Điều chế mã đa tần rời rạc DMT (Discrete Multitone)











 


Hình 2.7 Sơ đồ minh hoạ phương pháp điều chế DMT cho 3 tần số

f =f1
f=f2
f=f3
QAM-16
QAM-4
QAM-4