暨南大學電機系魏學文 [email protected] VDSL 技術介紹 MULTIMEDTIA TO THE HOME

暨南大學電機系魏學文

[email protected]

VDSL 技術介紹

MULTIMEDTIA TO THE HOME

暨南大學魏學文- 2 -

References

• Part 1: Functional Requirements and Common Specification

• Part 2: Technical Specification for Single-Carrier Modulation (SCM) Transceivers

• Part 3: Technical Specification for Multi-Carrier Modulation (MCM) Transceivers


VDSL Transmission Schemes

• FTTEx–Fiber to the exchange

• FTTCab–Fiber to the cabinet

Fiber to the node & Fiber to the building


VDSL Access TechnologySource: Orkit Co.


FTTB + VDSLSource: Orkit Co.

Building

Fiber


FSAN reference architecture


VDSL Reference Model

Application

Specific

NetworkInterface

Application

Specific

CustomerInterface

LT RTSplitter

NIDSplitter

γ-Oγ -R

Hypothetical applicationindependent interface (HAPI)

α

Hypothetical applicationindependent interface (HAPI)

β

U2 -O U2 -RU1 -RU1 - O

VTU-RVTU-O

PTSN or

ISDN

PTSN or

ISDN

PMS-TC & PMD PMS-TC & PMD

NID- Network InterfaceDevice protection anddistribution cable termination


Reference Model

-O V T U - O

Link Maintenance

U 2 -O U 1 -O

Application-

Specific processin g . (TPS-TC)

PMD

core

modem

NTR EOC

to PSTN

L i n k c o n t r o l

I-O

PMS-TC

FEC-US-F

FEC-US-S

FEC-DS-F

FEC-DS-S

splitter

LEGEND FEC = Forward Error Correction US = UpStream DS = DownStream NTR= Network Timing Ref. EOC = Embedded Operations Channel PSTN = Phone Network PMD = Physical Medium-Dependent TC = Transmission Convergence F = Fast or low-latency S = Slow or high-latency TPS = Transport Protocol-Specific

(Network Side)

U2-RU1-R

PMDcore

modem

linkcontrol

FEC US (F)

FEC US (S)

FEC DS (F)

FEC DS (S)

linkmaintenance

Application

Specific

(TPS-TC)

I-R

splitter

NTR

EOC

tophone

-R

NID

PMS-TC

LEGENDFEC = Forward Error CorrectionUS =UpStreamDS =DownStreamNID= Network Interface DeviceNTR = Network Timing Reference.EOC = Embedded Operations ChannelPMD = Physical Medium DependentTC = Transmission ConvergenceF = Fast or low-latencyS = Slow or High-latencyTPS = Transport Protocol Specific

premiseswiring

CustomerSide

processing


VDSL Protocol Reference Model

Transport Protocol (e.g. ATM) Transport Protocol (e.g. ATM)

TPS-TC TPS-TC

PMS-TC

PMD

PMS-TC

PMD

Private Private

Transmission Medium Internal Interface Internal Interface

γ - O

α I - O U 2 - O

γ - R

β I - R U 2 - R

VTU-O (LT) Layered Model VTU-R (NT) Layered Model U 1


VDSL Payload Bit Rate

Names of Service

Types

Downstream Data

Rate

(Mbps)

Upstream Data Rate

(Mbps)

Asymmetric 22 3

6 6 Symmetric

13 13


Service Distance

• S for short range (< 1 kft);

• M for medium range (1kft-3kft);

• L for long range (3kft-4.5kft).


VDSL maximum transmit power

Central Office Deployment Scenario

Cabinet Deployment Scenario

Downstream (dBm)

Upstream (dBm)

Downstream (dBm)

Upstream (dBm)

14.5 14.5 11.5 14.5 (?)


In-Band PSD (Down stream- Co case)

Frequency (kHz)

PSD (dBm/Hz)

Mask 1 Mask 2

0-4 -101 -101

25 - 40 - 40

1104 - 40 - 40

1622 -60 -50

3750 -60 -53.5

3750 - 5200 Out-of-band PSD

5200 -60 -55

8500 -60 -55



TX PWR= 14.5 dBm


In-Band PSD (Down stream- Cab case)


IN-Band PSD (Upstream-CO)

Frequency (kHz)

PSD (dBm/Hz)

Mask 1 Mask 2

0 – 4 - 101 - 101

25 - 38 - 38

138 - 38 - 38


3750 -60 -53

5200 -60 -53

5200 - 8500

Out-of-band PSD

8500 -60 -54

12000 -60 -54


Out of Band PSD

ftr1

f

Pmax, dBm (in a 1MHz window)

PSD, dBm/Hz

Transmit band

-80 dBm/Hz

PSDmax, dBm/Hz

fT

Transmit band

Receive band

fT

ftr2

Transitionband

Transitionband

Frequency

MHz

Maximum PSD

(PSDmax), dBm/Hz

Maximum Power in a 1MHz sliding window

Pmax, dBm

< 0.12 -120 -

0.12 - 0.225 -110 -

0.225-4.0 -100 -

4.0 -5.0 -100 -50

5.0 - 30.0 -100 -52

>=30.0 -120 -

Transition frequency

-80 -

fT <= 175 kHz


VDSL Band Allocation

1st Downstream (1D) 1st Upstream (1U) 2nd Downstream (2D) 2nd Upstream (2U)

f1 f2 f3 f4 f5 Frequency

Separating Frequencies (MHz)

f1 f2 f3 f4 f5

0.138 3.75 5.2 8.5 12

VDSL transceiver shall use Frequency Division Duplexing (FDD) to separate upstream and downstream transmission.


PMD Functional Model for SCM Systems

Input Frames

MUX Splitter

Output Frames

Encoder 2Decoder 2

Modulator 1Demodulator 1

Band-passFilter 1

Band-passFilter 1

Encoder 1Decoder 1

Modulator 2Demodulator 2

Band-passFilter 2

Band-passFilter 2

Diplexer

To the transmission media

Carrier 2 Carrier 1Carrier 2 Carrier 1

OAM EntityI- interface

PMDmanagement

U2- interface

PM

D S

ubl

ayer

PM

S-T

CM

edia


PMD Functional Model for MCM Systems

Input framesOutput frames

To transmission medium

DataDecoder

DataEncoder PMD

management

DemodulatorModulator

Multi-carrierModulation

Cyclicextension

Windowing

Hybrid

OAM entity

I interface

U2 interface

PM

S-T

CP

MD

Med

ia

QAM/CAP VDSL 技術


Single Carrier Modulation (SCM)- QAM/CAP

Modulator

ConstellationEncoder

In-PhaseFilter

Band-passFilter

QuadratureFilter

+

-

In

Qn

InputData

TransmitSignal

ConstellationEncoder

Band-passFilter

cos(2fct)

sin(2fct)

+

-

In

Qn

InputData

TransmitSignal

Modulator

Low-passFilter

Low-passFilter


Modulation

• CAP/QAM

• Constellation point: 4, 8(optimum), 16, 32, 64, 128, 256

• Differential encoding

• Spectral shaping filter

• Carrier spectral shaping

• FEC: RS code over GF(28), codeword= 255, t = 0, 1, 2, 8


8-point Constellation and Bit Mapping

1 1

11

0 0

0 0

+3

+1

-1

-3

+3+1-1-3

Qn

In


Differential Bit Encoding

1-1

1

-1

Qn

In

10 00

1101

b1b2


Symbol Rates and Carrier Frequencies

All available symbol rates (SR) in both downstream and upstream directions shall be multiples of the Basic Symbol Rate (BSR):

SR = BSR s

where s is an integer, BSR = 67.5 kbaud.

The carrier signal frequencies for transmitters using BSS should be a rational multiple of BSR/2:

fc = BSR/2 k, [MHz],

where k is an integer. The resulting shifting granularity is equal to 33.75 kHz.


Asymmetric Profiles: Bit Rates

Profile code Carrier Symbol RateRS

(Mbaud)

Constell.C

Data RateDR

(Mb/s)

Total RateTR

(Mb/s)

Maximum Payload Rate

(Mb/s)

AL-32OA 1D 2.160 (32x67.5)

32 10.8 DS 10.8 9.653

1U 0.945 (14x67.5)

4 1.89 US 1.89 1.689

AL-12ON 1D 2.700 (40x67.5)

64 16.2 DS 16.2 14.48

1U 0.945 (14x67.5)

8 2.835 US 2.835 2.534

1D 2.160 (32x67.5)

64 12.96 DS 17.28 15.445

AM-21OA 2D 2.160 (32x67.5)

4 4.32

1U 0.945 (14x67.5)

32 4.725 US 4.725 4.223

1D 2.700 (40x67.5)

256 21.6 DS 25.920 23.168

AM-01ON 2D 2.160 (32x67.5)

4 4.32

1U 0.945 (14x67.5)

32 4.725 US 4.725 4.223

1D 2.160 (32x67.5)

256 17.28 DS 25.920 23.168

AM-01OA 2D 2.160 (32x67.5)

16 8.64

1U 0.945 (14x67.5)

32 4.725 US 4.725 4.223


Asymmetric Profiles: Band Allocation fC

fLOW

fHIGH

Profile code

Carrier Carrier frequency(MHz)

Lowest frequency(MHz)

Highest frequency(MHz)

Maximum PSD

(dBm/Hz)

AL-32OA 1D 2.2275 (66x33.75) 0.93 3.52 -60

1U 4.5225 (134x33.75) 3.96 5.09

AM-12ON 1D 1.8225 (54x33.75) 0.2 3.44

1U 4.5225 (134x33.75) 3.96 5.09

1D 2.2275 (66x33.75) 0.93 3.52

AM-21OA 2D 6.885 (204x33.75) 5.59 8.18

1U 4.5225 (134x33.75) 3.96 5.09

1D 1.8225 (54x33.75) 0.2 3.44

AM-01ON 2D 6.885 (204x33.75) 5.59 8.18

1U 4.5225 (134x33.75) 3.96 5.09

1D 2.2275 (66x33.75) 0.93 3.52

AM-01OA 2D 6.885 (204x33.75) 5.59 8.18

1U 4.5225 (134x33.75) 3.96 5.09


Symmetric Profiles: Bit Rates

Profile code Carrier Symbol RateRS

(Mbaud)

Constell.C

Data RateDR

(Mb/s)

Total RateTR

(Mb/s)

Maximum Payload Rate

(Mb/s)

SL-32OA 1D 1.620 (24x67.5)

8 4.86 DS 4.86 4.334

1U 0.945 (14x67.5)

32 4.725 US 4.725 4.223

1D 1.890 (28x67.5)

16 7.56 DS 7.56 6.757

SM-33OA 1U 0.945 (14x67.5)

32 4.725 US 7.56 6.757

2U 1.4175 (21x67.5)

4 2.835

1D 2.160 (32x67.5)

128 15.12 DS 15.12 13.515

SS-03OA 1U 0.945 (14x67.5)

64 5.67 US 14.31 12.791

2U 2.160 (32x67.5)

16 8.64


Symmetric Profiles: Band Allocation

fC

fLOW

fHIGH

Profile code

Carrier

Carrier frequency(MHz)

Lowest frequency(MHz)

Highest frequency (MHz)

Maximum PSD

(dBm/Hz)

1D 1.890 (56x33.75) 0.92 2.87 -60

SL-32OA 1U 4.5225 (134x33.75) 3.95 5.09

2U 10.125 (300x33.75) 9.27 10.98

1D 2.0925 (62x33.75) 0.96 3.23

SM-33OA 1U 4.5225 (134x33.75) 3.95 5.09

2U 10.125 (300x33.75) 9.27 10.98

1D 2.2275 (66x33.75) 0.93 3.52

SS-03OA 1U 4.5225 (134x33.75) 3.96 5.09

2U 10.530 (312x33.75) 9.23 11.83


Spectral Shaping Filters

g t

tT

tT

tT

tT

tT

( )sin( ) ( )cos( )

( )[ ( ) ]

45

45

65

145

2

p t g t f tc( ) ( ) cos( ) 2

square-root raised-cosine ( = 0.20 )

q t g t f tc( ) ( ) sin( ) 2


Carrier Spectrum Shaping

Normalized frequency x Lower Bound dB Upper Bound dB

-1.5 < - 40- 1.4 < - 40- 1.3 < - 30- 1.2 < - 24-1.1 -20.0 -8.0-1.0 -5.0 -3.0-0.9 -2.7 -0.7-0.8 -2.0 0

0 -2.0 00.8 -2.0 00.9 -2.7 -0.71.0 -5.0 -3.01.1 -20.0 -8.01.2 < - 241.3 < - 301.4 < - 401.5 < - 40

2/SR

ffx c


VDSL chip: QAM structure

DMT VDSL 技術


Modulation

• DMT

• Sub-carriers: 2n+8; 256-4096

• Carrier spacing= 4.3125KHz (8.625kHz?)

• Using both CP and CF; 40-640

• Using block shaping: shaping length B <= 162n;

• Cyclic extension, CE= CP+CF – B = 402n

• Constellation point: 4, 8(PTT), 16, 32, …, 2k; 8<= k <= 15

• Pilot tones are optional

• Synchronous mode is optional

• FEC: RS code over GF(28), codeword <= 255, t =0, 12, …, 8; (240,224), (144, 128) are basic modes.


Cyclic extension and block shaping


CP and Sub-carriers

Cyclic extension expressed in samples

maximum of sub-carriers Nsc x 2n

40 256

80 512

160 1024

320 2048

640 4096


Symbol Rate


Timing Advance (TA)

• The VTU-R shall be capable of implementing a timing offset called timing advance (TA) in the transmission of DMT symbols.

• The TA forces the VTU-O/VTU-R pair to start transmissions of frames in opposite directions simultaneously (i.e. the frames in downstream and upstream transmission direction start at the same (absolute) time).

• The timing advance shall be equal to the propagation delay from the VTU-O to the VTU-R.

• It shall be calculated by the VTU-R during initialization.


Synchronous mode (optional)

• In synchronous mode, all VTU-O transceivers

in the same cable binder shall transmit with

respect to a common symbol clock, and thus

start the transmission of DMT symbols at the

same time.


Filtered Multi-tone ?


Frequency response of prototype filter


TLV3220VD30 (TI)


TLV3220VD30 (TI)

RFI Cancellation


頻帶重疊所造成的 RFI

VDSL 與某些 Radio Transmission 產生 Electromagnetic Compatibility(EMC)

的問題 :

- 商業調幅 (AM) 廣播服務 : 長波 (LW) ，中波 (MW) 頻段， 535 ~ 1605 kHz

- 業餘無線電 (Amateur Radio): 散佈在離散的頻段上 .

- 一些目前未列入考慮的訊號源，例如短波 (SW) 發射機 .

Copy from 卲玄綺

Source: Orkit Co.


雜訊侵出 (Egress)問題曝露於室外的雙絞線會如同天線般輻射能量的原因 - 電話線路的平衡度 (balance) 隨著頻率增加而遞減一般電話線的平衡度在 60 dB 以上 ( 語音頻率 ) ，隨頻率增加會降至 10~30

dB

- VDSL 訊號的頻率增加 ( 波長變短 ) 造成纜線的天線輻射效率增加

VDSL 產生電磁波干擾 (EMI)

Aerial Dropwire

Copy from 卲玄綺


雜訊侵入 (Ingress)問題曝露於室外的雙絞線會如同天線般接收干擾 - 纜線會接收來自於外部其他訊號源的射頻訊號造成干擾 - 在近距離內的 AM 發射站台會對 VDSL 產生嚴重的威脅

Aerial Dropwire

Copy from 卲玄綺


VDSL PSD MASK

SOURCE: IEEE Commun. Mag.


調幅廣播射頻雜訊特性與模型建構

調幅廣播訊號以 30 % AM DSB-TC (Double Sideband with Transmission

Carrier) 來產生 :

高斯雜訊源低通濾波器Cutoff : 5 kHz

雙邊帶振幅調變

fc

調整雜訊功率至指定的強度

產生雜訊

)2(cos])(1[)( tftmkAts cacAM

頻寬 = 10 kHz

訊號源 m(t)頻寬 = 5 kHz

Copy from 卲玄綺


調幅廣播射頻雜訊特性與模型建構

6.45 6.5 6.55 6.6 6.65 6.7 6.75

x 105

-130

-120

-110

-100

-90

-80

-70

-60

-50

Frequency (Hz)

Modula

ted s

ignal(A

MD

SB

) P

SD

(dB

m/H

z)

Carrier Frequency: 660 kHzAverage Power: -30 dBm

0 0.5 1 1.5 2

x 106

-130

-120

-110

-100

-90

-80

-70

-60

-50

Frequency (Hz)

PS

D o

f AM

Ra

dio

No

ise

Mo

de

l1 (

dB

m/H

z)

AM 雜訊之頻譜

頻率 : 660 kHz, 功率 -30dBm

ANSI T1E1.4 AM RFI Threat Model 1 之頻譜代表 10 個不同頻率 , 距離的 AM 發射機

Copy from 卲玄綺


業餘無線電射頻雜訊特性與模型建構

業餘無線電頻帶分布

開始頻率(MHz)

截止頻率(MHz)

1.800 2.000

3.500 3.800

7.000 7.100

10.100 10.150

14.000 14.350

18.068 18.168

21.000 21.450

24.890 24.990

28.000 29.100

ANSI 所認可的業餘無線電頻帶

開始頻率(MHz)

截止頻率(MHz)

1.800 2.000

3.500 4.000

7.000 7.300

10.100 10.150

14.000 14.350

18.068 18.168

21.000 21.450

24.890 24.990

28.000 29.100

ETSI 所認可的業餘無線電頻帶

Copy from 卲玄綺



業餘無線電訊號以 AM-SSB(Single Sideband) 來產生 :

)2(sin)(ˆ2

1)2(cos)(

2

1)( tftmAtftmAts ccccSSBAM

高斯雜訊源符合 ITU-TRec. G .227的濾波器

單邊帶振幅調調變

fc

調整雜訊功率至指定的強度輸出

Copy from 卲玄綺



0 1 2 3 4 5

x 10-3

-1

0

1

2

3

4

5

6

7x 10

-4

time(sec)

Pul

se R

esp

ons

e

時域脈波響應符合 ITU-T Rec.G.227 的語音頻率響應

IFFT

產生符合 ITU-T Rec.G.227 的濾波器的方式

Copy from 卲玄綺



Amateur Radio 雜訊之頻譜

頻率 : 1.81 MHz, 功率 : -5 dBm

1 1.2 1.4 1.6 1.8 2

x 106

-180

-160

-140

-120

-100

-80

-60

-40

-20

Frequency (Hz)

Mo

dul

ate

d s

igna

l(AM

SS

B)

PS

D (

dB

m/H

z)

Carrier Frequency: 1.81 MHzAverage power: -5dBm

Copy from 卲玄綺


RFI CANCELLER

SOURCE: IEEE Commun. Mag.

Documents

暨南大學 電機系 魏學文 [email protected] VDSL 技術介紹 MULTIMEDTIA TO THE HOME

暨南大學電機系魏學文 [email protected] VDSL 技術介紹 MULTIMEDTIA TO THE HOME