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Vectoring De-mystified
• Market Drivers
• Understanding Vectoring
• Vectoring Described
• Benefits of System-Level
Implementation
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National Goals by 2020:Ubiquitous 100Mbps Broadband
Reaching 2020 Goal is of National and Global Importance
US:100Mbps to 100 Million households
France:100Mbps to 70% of subscribers
Australia:100 Mbps to 90% households
Germany:100Mbps to 50% of subscribers
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It impacts a country’s well being
“Savings in the health sector …to fall between 1.4% and 3.7% as a direct result of having the new network in place.”
ITU National Broadband Plan Recommendations
“… 10 percent increase in broadband penetration …1.3 percent additional growth GDP.”
ITU National Broadband Plan Recommendations
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And Drives Business Success
Launched in the last 6 years Super connected subscribers will lead to new industries and companies we can’t even imagine yet
Higher bandwidth results in more exciting applications which leads to increased adoption and higher revenue per user
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100Mbps+ Downstream: 25x faster than today’s average
4Mbyte photo in
1/3 second
A complete album in
5 sec
An Entire HD movie in less than 10 min
Multi-angle 3D HDTV
Cloud based Multi-screen 3D Gaming.
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100Mbps: A Key Service Offering
• 100Mbps services will be mainstream by 2015
Source: Infonetics 2012
By 201539% plan to provide services >100 Mbps
Today52% of services are 1-10 Mbps
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• Numerous national and regional broadband plans give 100Mbps as a targeted speed
• Cable operators are able to offer a 100Mbps tier with DOCSIS 3.0
100Mbps: A Key Service Offering
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Can Wireline Service Providers Compete?
• FTTH is the ultimate goal but still cost-prohibitive in many deployment scenarios
• Telcos can be competitive with copper – 100Mbps is practical and economical with VDSL2 vectoring and bonding
• Let’s see how…
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Vectoring De-mystified
• Market Drivers
• Understanding
Vectoring
• Vectoring Described
• Benefits of System-Level
Implementation
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VDSL2 Fundamentals - Discrete Multi-Tone
DMT Line Code Is Made Up of Individual Sinusoidal Carriers Whose Amplitude and Phase Change to Signal the Data Bits
The VDSL2 (G.993.2 ) Has Tone Spacing of 4.3125 kHz – 8.625 kHz for Profile 30a.
The Upstream Spectrum is Separated From Downstream. This Type of Segregation is Frequency Division Duplexing (FDD)
Frequency (MHz)
Upstream
Downstream
Upstream
Downstream
Upstream
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DMT Tone Modulation
These figures illustrate the real and imaginary QAM amplitudes for 2, 3 & 4 bit tone modulations on each tone.
Each tone carries some number of bits (1≤ bits ≤ 15) based on its signal-to-noise ratio (SNR).
5
0
1 7
24
3
6
-3 -1 +1 +3
+3
+1
-1
-3
2 0
3 1
1 3
0 2
5 7
4 6
10
11
8
9
1513
12 14
-3 -1 +1 +3
+3
+1
-1
-3
+1
+1
-1
-1
Two bits
Three bits
Four bits
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What Is Crosstalk?
DSL2
DSL1DSL1
DSL2
FEXT CouplingFEXT Coupling
DSL2
DSL1DSL1
DSL2
NEXT CouplingNEXT Coupling
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ANSI Crosstalk Noise Models
LLfHfnXLnfCouplingFEXT F 20.26.0 ),(),,(_
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How Many Bits On Each Tone?
The Number of Bits Carried on Each Tone is Determined by The Effective Signal to Noise Ratio (SNR) Around That Tone.
The Greater the SNR, the More Bits Carried on the Tone
2/
2/10
2
10)(
)(1log)(
ff
ff fNoise
fRcvfC
SNR
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ADSL2+ 11 Bit Constellation
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What is Vectoring?
G.vectorMultiport
xDSL
Vectored Signal Processing Compensates for the Crosstalk
Between the Cable Pairs
+FEXT
+FEXT
+FEXT
-FEXT
-FEXT
-FEXT+FEXT
+FEXT
+FEXT
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G.Vector ITU Recommendation G.993.5
NormalMultiport
xDSL
Crosstalk Between Cables ActsAs Noise Sources in the Upstream
and Downsteam
G.vectorMultiport
xDSL
Vectored Signal Processing Compensates for the Crosstalk
Between the Cable Pairs
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Why Vector Profile 17 Instead of Using Profile 30?
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Why Vector Profile 17 Instead of Profile 30?
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Vectoring De-mystified
• Market Drivers
• Understanding Vectoring
• Vectoring Described
• Benefits of System-Level
Implementation
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Vectoring Modifications to StartupG.994.1
Handshake phaseDownstream
Direction
O-P-VECTOR 1Estimation of FEXT channels from the initializing line into
vectored lines
G.992.3 Channel Discovery Phase
O-P-VECTOR 1-1Re-estimation of FEXT
channels from the initializing line into vectored lines
G.992.3Training Phase
O-P-VECTOR 2
O-P-VECTOR 2-1Estimation of FEXT channels
from and into the initializing line
G.992.3Channel Analysis and
Exchange phase
G.994.1 Handshake phase
Upstream Direction
R-P-VECTOR 1Estimation of FEXT channels from the initializing line into
vectored lines
G.992.3 Channel Discovery Phase
R-P-VECTOR 1-1Re-estimation of FEXT
channels from the initializing line into vectored lines
G.992.3Training Phase
R-P-VECTOR 1-2
R-P-VECTOR 2Estimation of FEXT channels
from and into the initializing line
O-P-TRAINING V1
R-P-QUIET V1
G.992.3Channel Analysis and
Exchange phase
O-P VECTOR 1 allows existing vectored pairs to learn FEXT couplings from the new line
O-P Vector 1 composed of pilot modulated sync symbols & quiet symbols
Special OperationsChannel (SOC) Active
New Line Error Feedback
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Aligned Synch Symbols Enable Training
Down Synch 1 DMT 2 DMT 3 DMT 4
timeDown Synch 1 DMT 2 DMT 3 DMT 4
timeDown Synch 1 DMT 2 DMT 3 DMT 4
time
DMT 1 DMT 2 DMT 3 Up Synch 4
timeDMT 1 DMT 2 DMT 3 Up Synch 4
timeDMT 1 DMT 2 DMT 3 Up Synch 4
time
Down Synch 1
timeUp Synch 4
time
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Estimating the Crosstalk.
Y
X
+1
+1
ex
ey
Constellation boundary
Constellation boundary
ConstellationDecision point
Received normalized
sample
In-phase error
Quadrature error
Complex normalized error
sample
C^
Z
E
The CPE reports the slicer error measured on the synch symbols and sends it back to the DSLAM
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DSL Transceivers
EncoderFramer
EncoderFramer
EncoderFramer
EncoderFramer
Modulator
Modulator
Modulator
Modulator
DSL Transceiver
DSL Transceiver
DSL Transceiver
DSL Transceiver
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G.993.5: G.vector
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
Vector Control Entity
Precoder
Precoder
Precoder
Precoder
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G.993.5: G.vector
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
Vector Control Entity
Precoder
Precoder
Precoder
Precoder
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
EncoderFramer Modulator
Vector Control Entity
Precoder
Precoder
Precoder
Precoder
DSL Modem
DSL Modem
DSL Modem
DSL Modem
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G.vector: Vector Control Entity (VCE)
Framer Modulator
Framer Modulator
Framer Modulator
Framer Modulator
Vector Control Entity
Precoder
Precoder
Precoder
Precoder
DSL Modem
DSL Modem
DSL Modem
DSL Modem
Vector Control Entity (VCE):•coordinates initialization of DSL links: orderly join/leave process
Encoder
Encoder
Encoder
Encoder
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G.Vector Steady State Operation
Vector Control Entity
VCE:•Synchronizes timing and aligns “sync” symbols on DSL links•VCE instructs encoders to transmit probing signal during sync symbols•Modems send error signals to VCE•VCE updates coefficients for precoders
EncoderFramer ModulatorPrecoder
EncoderFramer ModulatorPrecoder
EncoderFramer ModulatorPrecoder
Data Data Data Sync Data Data Data
Data Data Data Sync Data Data Data
Data Data Data Sync Data Data Data
Encoder
Encoder
Encoder
DSL Modem
DSL Modem
DSL Modem
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G.vector: Adding a Line
Vector Control Entity
• VCE instructs encoder for joining modem to be silent during data symbols • Instructs all encoders to transmit probing signals during sync symbols• Modems send error signals to VCE• VCE learns crosstalk couplings from joining modem, updates coefficients for
precoders• Joining modem can now send data
EncoderFramer ModulatorPrecoder
EncoderFramer ModulatorPrecoder
EncoderFramer ModulatorPrecoder
EncoderFramer ModulatorPrecoder
Data Data Data Sync Data Data Data
Data Data Data Sync Data Data Data
Data Data Data Sync Data Data Data
Data Data Data Sync Data Data Data
Encoder
Encoder
Encoder
Encoder
DSL Modem
DSL Modem
DSL Modem
JoiningModem
DSL Modem
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Board Level FEXT Cancellation (across DSPs and VCE)
DSP 1 DSP 2
DSP 3 DSP 4
Ca
ble
Pla
nt
32ADTRAN 2010 All rights reserved
Background on Binders
Binder 1
Binder 2Binder 3
New line cards or additional systems added
No 1 to 1 correlation between systems and bindersNo 1 to 1 correlation between systems and binders
33ADTRAN 2010 All rights reserved
The Problem with VectoringSome Pairs Cannot be part of the Team
Crosstalk (FEXT)
Pairs in the same binder need to be handled as a single group to effectively implement vectoring
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Deployment Strategy – FEXT Cancellation = Binder Management
24 Port FEXT WD-IDFC with 17.5 dBm VDSL2 (ADTRAN 100 Pair Cable; 75 % Take Rate - 48 Alien)
15
20
25
30
35
40
45
50
55
60
65
1000 1500 2000 2500 3000 3500 4000 4500 5000
Loop Length (ft)
Do
wn
stre
am R
ate
(Mb
ps)
0 Pairs Binder Managed
4 Pairs Binder Managed
12 Pairs Binder Managed
0 Pairs Random Deployment
4 Pairs Random Deployment
12 Pairs Random Deployment
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Measured Results: Downstream
0
10
20
30
40
50
60
70
80
90
100
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Rate
(Mbp
s)
Port #
Measured Data: 300 m 17A VDSL2 Downstream(26 AWG ~= 0.4 mm 48 links in 50 pair twisted pair cable
FEXT Free
Cable Vectoring
Binder Vectoring
No Vectoring
67 Mbps
81 Mbps (+21%)
99 Mbps (+50%)
Min Data Rate
Binder Vectoring:24 (Left) Vectored + 24 (Right) unvectored
Cable Vectoring:48 lines (24L (rates shown) + 24R)in one vector group
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Measured Results: Upstream
Binder Vectoring:24 (Left) Vectored + 24 (Right) unvectored
Cable Vectoring:48 lines (24L (rates shown) + 24R)in one vector group
0
10
20
30
40
50
60
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24
Rate
(Mbp
s)
Port #
Measured Data: 300 m 17A VDSL2 Upstream(26 AWG ~= 0.4 mm 48 links in 50 pair twisted pair cable
FEXT Free
Cable Vectoring
Binder Vectoring
No Vectoring
17 Mbps
27 Mbps (+56%)
36 Mbps (+111%)
Min Data Rate
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Vectoring De-mystified
• Market Drivers
• Understanding Vectoring
• Crosstalk, Bonding and
Binder Management
• Vectoring Described
• Benefits of System-
Level Implementation
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System Level FEXT Cancellation
DSP 1 DSP 2
DSP 3 DSP 4 Ca
ble
Pla
nt
DSP 1 DSP 2
DSP 3 DSP 4 Ca
ble
Pla
nt
DSP 1 DSP 2
DSP 3 DSP 4 Ca
ble
Pla
nt
39ADTRAN 2010 All rights reserved
The Solution is a System ApproachLetting Everyone Join the Team
Crosstalk (FEXT)
Multiple OSP DSLAMs or Chassis Cards need to work together as a “system” so that vectoring can be performed across line cards or other OSP DSLAMs
40ADTRAN 2010 All rights reserved
Board Level to System Level Upgradeability
DSL Modem
Binder
Card 1
DSL Modem
DSL Modem
Card 2
Resource
Card 3
Card 44 Cards = 192 Ports
3 Cards = 144 Ports
2 Cards = 96 Ports
1 Cards = 48 Ports
41ADTRAN 2010 All rights reserved
OSP Board Level to System Level Upgradeability
DSL Modem
Binder
DSL Modem
DSL Modem
System level vectoring OSPs
DSL Modem
Initially Single OSP has internal BLV
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FEXT Cancelled Group 96 Pairs No Alien Disturbers
96 Port FEXT WD-IDFC with 17.5 dBm VDSL2 (100 Pair Cable; ~100% Take Rate - No Alien)
46.0
975
42.3
628
39.3
223
35.4
266
28.7
862
23.9
531
22.6
768
19.9
8
17.0
189
52.2
771
48.6
027
45.4
476
40.7
892
33.0
877
27.4
467
24.5
257
21.5
953
18.2
989
54.1
611
50.4
584
47.1
874
42.2
592
34.2
689
28.5
832
25.2
749
22.2
604
18.9
67
55.7
737
52.1
054
48.7
38
43.4
046
35.1
866
29.3
747
25.9
316
22.7
762
19.3
414
59.8
433
56.2
349
52.7
167
46.4
136
37.4
983
31.2
089
27.4
054
23.9
024
20.2
696
67.0
601
63.3
984
59.0
322
51.0
869
40.8
826
33.7
211
29.2
111
25.3
735
21.4
84
82.3
435
70.5
867
57.3
389
44.4
597
35.9
737
31.3
308
26.8
474
22.5
406
91.7
855
0
10
20
30
40
50
60
70
80
90
100
1000 1500 2000 2500 3000 3500 4000 4500 5000
Loop Length (ft)
Do
wn
stre
am R
ate
(Mb
ps)
No Pairs Removed 1%
4 Pairs Removed 1%
8 Pairs Removed 1%
12 Pairs Removed 1%
24 Pairs Removed 1%
48 Pairs Removed 1%
96 Pairs Removed 1%
43ADTRAN 2010 All rights reserved
Vectoring Benefits and Considerations
• Vectoring has the potential to cancel crosstalk in a binder:• All users see rates as if
they were the onlyuser in the cable
Benefits– 30-50% improvement in
speed– Reach 100Mpbs with 2
pair bonding
Considerations– Limited to short loops
(less than 3,000ft)– Need system level
approach
0
20
40
60
80
100
120
140
500 1000 1500 2000 2500 3000
Rate
(Mbp
s)
Reach (feet)
Upstream, 12-self crosstalk
26 AWG equivalent: Multiply vectored reach by 1.3 for 24 AWG
100
Mbp
s to
> 2
500
ft,
Usi
ng 2
pai
rs
44ADTRAN 2010 All rights reserved
Downstream Performance Full Cancellation
45ADTRAN 2010 All rights reserved
Upstream Performance Full Cancellation
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Conclusions
• Complexity of FEXT cancellation will result in longer port training times.
• FEXT cancellation for VDSL2 shows great promise for applications in which:–cable size matches the in-domain group size–system level deployment is implemented and group size matches
or exceeds the binder size– loops are short–alien crosstalk is minimal.
• After FEXT is removed, the resulting low noise floor will likely increase performance sensitivity to impulse noise and component non-linearity
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Key Takeaways
• System-level approach is best
• Best gains (30-50%) with short loops. (<1000ft)
• Vectoring is a short loop technology not suitable for CO deployments
• ADTRAN knows vectoring.
In 2008, ADTRAN received the “Award for Outstanding Contributions to an ATIS Forum or Committee”. This achievement was in recognition for our initiative to provide the industry with a FEXT Channel Model needed for the analysis of FEXT cancellation techniques used in vectoring.
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Thank YouPlease visit: http://adtran.com to learn more.Email [email protected] or call 800-9ADTRAN