Ethernet in the First Mile - IEEEgrouper.ieee.org/groups/802/3/efm/public/mar02/beck_2_0302.pdf ·...
Transcript of Ethernet in the First Mile - IEEEgrouper.ieee.org/groups/802/3/efm/public/mar02/beck_2_0302.pdf ·...
DMT-VDSL Proposal Page 1Ethernet in the First Mile
Ethernet over VDSL
DMT Concepts and Advantages
IEEE 802.3ah Ethernet in the First Mile
Saint Louis, March 11-14 2002
DMT-VDSL Proposal Page 2Ethernet in the First Mile
Supporters
� Michael Beck, Alcatel
� Behrooz Rezvani, Ikanos
� Christophe Del-Toso, ST Microelectronics
� Sedat Oelcer, IBM
� Tariq Haddad, Zarlink
� Massimo Sorbara, GlobespanVirata
� Doug Artman, Texas Instruments
DMT-VDSL Proposal Page 3Ethernet in the First Mile
Overview
� Ethernet over VDSL for EFM over Point-to-Point Copper� DMT Concepts
� Modulation Technique� Windowing, RFI Canceling� Digital Duplexing
� Specification of DMT-VDSL� Advantages of DMT-VDSL
� RFI Robustness� EMC Friendly� Spectral Flexibility� PSD Control
� Availability of DMT-VDSL� Possible Additions to DMT-VDSL� Conclusions
DMT-VDSL Proposal Page 4Ethernet in the First Mile
EFM over Point-to-Point Copper Ethernet over VDSL
� This line code proposal should be seen as a proposal to further narrow down the existing Ethernet over VDSL baseline.
MAC Control (Optional)
MAC – Media Access Control
Reconciliation
Ethernet-over-VDSL AL
PMS-TC
PMD
MII �
PTM-TC
MDI �voice grade Cu
PCS �
PMA �
PMD �From existing DMT-VDSL standards
TO BE DEFINED
From G.993.1/H
DMT-VDSL Proposal Page 5Ethernet in the First Mile
VDSL-DMT ConceptsModulation Technique
IFFT
ADCFFT
Receiver
Transmitter
TXDataRXData
Extract Cyclic Prefix
CopperPair
××××SI
PO
FEQ
+ R
otor
Dem
appe
r
PISO
Hybrid &
splitter
PISO
Map
per
SIPO DAC
Windowing
Folding
RFI
can
celle
r
Driver××××
WindowingR
otor
Cyclic Prefix
LPF
AGC LPF
FDD DMT VDSL
DMT-VDSL Proposal Page 6Ethernet in the First Mile
DAC
S/P
FFT
FEQ
IFFT P/S
0
Tx clock
Discreteequivalent
channel
Rx clock
p(t)
Tx filter Channel Rx filter
ch(t) r(t) ADC
DMT ConceptsModulation Technique
DMT-VDSL Proposal Page 7Ethernet in the First Mile
DMT ConceptsModulation Technique
� DMT is similar to OFDM (as used in 802.11a, DAB, DVB)� ADSL compatible tone spacing (4.3125 kHz)� 12 MHz bandwidth, as specified in ITU-T
POTSfrequency
psdQAM-modulatedsubchannel (tone) individually optimized as a function of impairments
DMT-VDSL Proposal Page 8Ethernet in the First Mile
� constellation size and power of each tone are optimized in function of loop attenuation and noise environment
� optional rate adaptation at startup to provide maximum rate over given loop
� optional dynamic rate adaptation to track variations in loop attenuation or noise environment
� optional power boost on long lines
� power reduction on short lines (politeness)
� optional spectral shaping (including tone masking)
DMT ConceptsBit Loading
DMT-VDSL Proposal Page 9Ethernet in the First Mile
1 0
1 3
1 6
1 9
2 2
2 5
2 8
- 3
- 2
- 1
0
1
2
3
4
SNR
gi
bi=4
bi=3
bi=2
bi=1
bi=5
)arg
.1(log 2 emgainSNRbi γ
+=Target Bit error rate= 10-7
DMT ConceptsBit Loading
DMT-VDSL Proposal Page 10Ethernet in the First Mile
DMT ConceptsWindowing
CP CSFFT window
windowingat receiver
windowingat transmitter
DMT symbol duration
DMT-VDSL Proposal Page 11Ethernet in the First Mile
� Windowing at the transmitter: � Reduces frequency domain sidelobes
�Reduces the out of band power of the NEXT signal
�Allows for digital duplexing
�Guarantees spectral compatibility with other services
DMT ConceptsWindowing (transmitter)
DMT-VDSL Proposal Page 12Ethernet in the First Mile
DMT ConceptsNEXT with/without Windowing
DMT-VDSL Proposal Page 13Ethernet in the First Mile
DMT ConceptsWindowing (receiver)
� Windowing at the receiver :
� Reduces Inter Symbol Interference (ISI)
� Reduces the susceptibility to RFI
DMT-VDSL Proposal Page 14Ethernet in the First Mile
� Interferer: � 4 kHz wide single side-band signal� AM modulated with Gaussian noise
-120
-100
-80
-60
-40
-20
0
0 10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200 210 220 230 240 250
tone index
mag
nitu
de in
dB
residual error basic DMT (rectangular window)
windowing
Tone index
Windowing
Mag
nitu
de in
dB
Basic DMT (rectangular window)
Residual error
DMT ConceptsWindowing (receiver) and RFI Canceling
DMT-VDSL Proposal Page 15Ethernet in the First Mile
DMT Concepts Digital Duplexing
prefix (CP)
suffix (CS)
FFT-size
NT Tx
LT Rxuseful
LT Tx
time
CS > propagation delay
LT Rx FFT-window
1 symbolpropagation delay
LT Rxecho
echo
DMT-VDSL Proposal Page 16Ethernet in the First Mile
Digital DuplexingSingle Solution Supporting Multiple Frequency Plans
down up updown
� plan 997 (ETSI + ITU-T) - optimized for symmetry
0.138 3.0 5.1 7.05 12.0 MHz
down up updown
� plan 998 (ETSI + T1E1 + ITU-T) - optimized for asymmetry
0.138 3.75 5.2 8.5 12.0 MHz
ADSL
0.138 1.1 MHz
down up updown
� flexible plan Fx (ITU-T)
0.138 3.752.5 Fx 12.0 MHz
DMT-VDSL Proposal Page 17Ethernet in the First Mile
Specification of DMT-VDSL
� DMT-VDSL standards are available:
� Very-High-Speed Digital Subscriber Lines (VDSL) Metallic Interface, Part 3: Technical specification of Multi-Carrier Modulation (MCM) Transceiver, ANSI, T1E1.4/01-013R2,Draft Specification.
� Transmission and Multiplexing (TM); Access transmission systems on metallic access cables; Very High speed Digital Subscriber Line (VDSL); Part 2: Transceiver specification, ref :ETSI, TS 101 270-2.
� DMT is also the line code of ADSL (standardized in ETSI, T1E1 and ITU-T) and G.Lite (ITU-T).
DMT-VDSL Proposal Page 18Ethernet in the First Mile
Advantages of DMT-VDSL
POTSfrequency
psd
DMT-VDSL Proposal Page 19Ethernet in the First Mile
unused tones
flexible carrier allocation to up- or downstream
POTSfrequency
psd
psd optimizedon tone per tone basis
� digital duplexing – different spectral plans with same hardware� easy spectral shaping
� ADSL/VDSL co-existence/co-location
� upstream power back-off� prevent radio ingress/egress (HAM radio)
Advantages of DMT-VDSLSpectral Flexibility
DMT-VDSL Proposal Page 20Ethernet in the First Mile
Advantages of DMT-VDSLSpectral Flexibility
� Three existing bandplans for public networks can be supported by the same hardware (the IFFT/FFT performs the filtering).
� New bandplans may be defined to suit specific requirements:
� Improved symmetry in private networks
� Improved spectral compatibility with legacy in-building networks (HPNA, 10/100BASE-T, …).
DMT-VDSL Proposal Page 21Ethernet in the First Mile
Advantages of DMTPSD Flexibility
� Upstream Power Back-Off:
� Standard UPBO requires shaped PSDs
� Improved Spectral Compatibility (fine granularity)
� w.r.t. other DSLs
� w.r.t. legacy in-building services
DMT-VDSL Proposal Page 22Ethernet in the First Mile
The flexibility of DMT modems is impressive. We can even draw pictures on the spectrum analyzer !
Confidential
Advantages of DMTPSD Flexibility
DMT-VDSL Proposal Page 23Ethernet in the First Mile
Advantages of DMTProven Technology
� DMT adapts itself to all line and noise conditions.
� DMT is the dominant line code in deployed DSL systems. ADSL has millions of lines active in the field.
� DMT-VDSL is available today.
DMT-VDSL Proposal Page 24Ethernet in the First Mile
Advantages of DMT-VDSLSimilarity between ADSL and VDSL
� DMT is the line code used by ADSL.
� DMT-VDSL hardware can be designed to be backward compatible with ADSL.
� DMT-VDSL can be used to create a scalable multi-mode system as described in nov01/del-toso_1_1101.pdf .
DMT-VDSL Proposal Page 25Ethernet in the First Mile
Advantages of DMTRFI Overview
E-field Types of interferers :a AM broadcast
(MW and SW)a Amateurs radio bands
(HAM radio)a Public safety & distress
bands
Common mode to differential mode conversion
Ingress Egress
Vcm
Vd
E-field
Vcm
Vd
E’-field
DMT-VDSL Proposal Page 26Ethernet in the First Mile
Advantages of DMTRFI Robustness
Effect of RFI on 1 km 24AWG loop
0
20
40
60
0 10Frequency in MHz
SNR
in d
B
No RFI1 RFI -20dBm @ 1.96 MHz1 RFI -20dBm @ 3.51 MHz2 RFIs -25dBm2 RFIs without cancellation
DMT-VDSL Proposal Page 27Ethernet in the First Mile
Possible Additions to DMT-VDSL
� New band plans (e.g. use of extended optional upstream band to provide more symmetry)
� Alternative Power Back-Off
� Advanced Coding Schemes
DMT-VDSL Proposal Page 28Ethernet in the First Mile
Availability of DMT-VDSL
� Multiple vendors have DMT-VDSL silicon on the market today.
� Several other vendors will have DMT-VDSL silicon on the market by end of 2002.
� Five of these have declared their intention to provide interoperable systems by end of 2002.
DMT-VDSL Proposal Page 29Ethernet in the First Mile
Conclusions
� DMT-VDSL is well suited for use in EFM/Copper:
� Frequency plan flexibility thanks to digital duplexing.
� Flexible PSDs thanks to IFFT based modulation.
� Similar architecture as ADSL allows for backward compatibility with this very successful technology.
� DMT-VDSL is fully standardized in ETSI and T1E1.4.
� Standard compliant transceiver chipsets are available from multiple vendors.