Vectoring Described

Report
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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
US:
100Mbps to
100 Million
households
France:
100Mbps to
70% of
subscribers
Germany:
100Mbps to
50% of
subscribers
Reaching 2020 Goal is of
National and Global
Importance
Australia:
100 Mbps to
90%
households
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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
Higher bandwidth results in more
exciting applications which leads
to increased adoption and higher
revenue per user
Launched in the last 6 years
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Super connected
subscribers will lead to new
industries and companies
we can’t even imagine yet
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100Mbps+ Downstream:
25x faster than today’s average
4Mbyte
photo in
1/3 second
Multi-angle
3D HDTV
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A
complete
album in
5 sec
An Entire HD
movie in less
than 10 min
Cloud based Multiscreen 3D Gaming.
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100Mbps: A Key Service Offering
• 100Mbps services will be mainstream by 2015
By 2015
39% plan
to provide
services
>100 Mbps
Today
52% of services
are 1-10 Mbps
Source: Infonetics 2012
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100Mbps: A Key Service Offering
• 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
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Can Wireline Service Providers Compete?
• FTTH is the ultimate goal but still costprohibitive 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)
Upstream
Upstream
Upstream
Downstream
Downstream
Frequency (MHz)
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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-tonoise ratio (SNR).
2
11
8
10
4
2
-3
+3
1
3
0
2
0
+1
-1
+1
3
-1
6
-3
+3
1
7
0
+1
-1
9
5
+3
+1
-3
+1
-1
+1
+3
Three bits
-1
3
Two bits
13
15
-1
5
7
12
14
-3
4
6
1
Four bits
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What Is Crosstalk?
NEXT Coupling
DSL1
DSL1
DSL2
DSL2
FEXT Coupling
DSL1
DSL1
DSL2
DSL2
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ANSI Crosstalk Noise Models
FEXT _ Coupling( f , n, L)  X F  n
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0.6
 f
2.0
 H( f , L )
2
L
14
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


Rcv
(
f
)


C( f )  
log2 1 
f  f / 2
 Noise ( f )   
1010 

f  f / 2
SNR
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ADSL2+ 11 Bit Constellation
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What is Vectoring?
-FEXT
G.vector
Multiport
-FEXT
xDSL
-FEXT
+FEXT
+FEXT
+FEXT
+FEXT
+FEXT
+FEXT
Vectored Signal Processing
Compensates for the Crosstalk
Between the Cable Pairs
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G.Vector ITU Recommendation G.993.5
Normal
Multiport
xDSL
Crosstalk Between Cables Acts
As Noise Sources in the Upstream
and Downsteam
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G.vector
Multiport
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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21
Vectoring Modifications to Startup
Downstream
Direction
O-P VECTOR 1 allows existing
vectored pairs to learn FEXT
couplings from the new line
G.994.1
Handshake phase
Upstream
Direction
G.994.1
Handshake phase
O-P-VECTOR 1
Estimation of FEXT channels
from the initializing line into
vectored lines
G.992.3
Channel Discovery Phase
R-P-VECTOR 1
Estimation of FEXT channels
from the initializing line into
vectored lines
G.992.3
Channel Discovery Phase
O-P Vector 1 composed of
pilot modulated sync
symbols & quiet symbols
Special Operations
Channel (SOC) Active
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O-P-VECTOR 1-1
Re-estimation of FEXT
channels from the initializing
line into vectored lines
R-P-QUIET V1
O-P-TRAINING V1
R-P-VECTOR 1-1
Re-estimation of FEXT
channels from the initializing
line into vectored lines
G.992.3
Training Phase
G.992.3
Training Phase
O-P-VECTOR 2
R-P-VECTOR 1-2
O-P-VECTOR 2-1
Estimation of FEXT channels
from and into the initializing line
R-P-VECTOR 2
Estimation of FEXT channels
from and into the initializing line
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New Line Error
Feedback
22
Upstream Ports
Downstream Ports
Aligned Synch Symbols Enable Training
Down Synch 1
Down Synch 1
Down Synch 1
DMT 2
DMT 2
DMT 2
DMT 3
DMT 3
DMT 3
DMT 4
DMT 4
DMT 4
time
time
time
DMT 1
DMT 1
DMT 1
DMT 2
DMT 3
DMT 2
DMT 3
DMT 2
DMT 3
Up Synch 4
Up Synch 4
Up Synch 4
time
time
New Port
time
Down Synch 1
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time
Up Synch 4
time
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Estimating the Crosstalk.
Y
Constellation boundary
E
Complex
normalized error
sample
Z
Received
normalized
sample
Quadrature
error
ey
The CPE reports
the slicer error
measured on the
synch symbols and
sends it back to the
DSLAM
+1
^
C
ex
In-phase
error
Constellation
Decision point
Constellation boundary
+1
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X
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DSL Transceivers
DSL Transceiver
Framer
Encoder
Modulator
Framer
Encoder
Modulator
Framer
Encoder
Modulator
Framer
Encoder
Modulator
DSL Transceiver
DSL Transceiver
DSL Transceiver
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G.993.5: G.vector
Framer
Encoder
Precoder
Modulator
Framer
Encoder
Precoder
Modulator
Framer
Encoder
Precoder
Modulator
Framer
Encoder
Precoder
Modulator
Vector Control Entity
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G.993.5: G.vector
Framer
Encoder
Framer
Framer
Framer
Modulator
Encoder
Precoder
Encoder
Precoder
Modulator
Encoder
Precoder
Modulator
Framer
Framer
Precoder
Encoder
Framer
Framer
DSL
Modem
Encoder
Precoder
Modulator
DSL
Modem
Precoder
Modulator
DSL
Modem
DSL
Modem
Modulator
Encoder
Precoder
Modulator
Encoder
Precoder
Modulator
Vector Control Entity
Vector Control Entity
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G.vector: Vector Control Entity (VCE)
Framer
Encoder
Precoder
Modulator
DSL
Modem
Framer
Encoder
Precoder
Modulator
DSL
Modem
Framer
Encoder
Precoder
Modulator
DSL
Modem
Framer
Encoder
Precoder
Modulator
DSL
Modem
Vector
Control
Entity
Vector Control Entity (VCE):
• coordinates initialization of DSL links: orderly join/leave process
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G.Vector Steady State Operation
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
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
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G.vector: Adding a Line
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
DSL
Modem
Framer
Encoder
Precoder
Modulator
Data
Data
Data
Sync
Data
Data
Data
Joining
DSL
Modem
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
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Board Level FEXT Cancellation
(across DSPs and VCE)
DSP 2
DSP 3
DSP 4
Cable Plant
DSP 1
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Background on Binders
Binder 1
New line cards
or additional
systems added
Binder 3
Binder 2
No 1 to 1 correlation between systems and binders
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The Problem with Vectoring
Some Pairs Cannot be part of the Team
Pairs in the same binder need to be
handled as a single group to
effectively implement vectoring
Crosstalk
(FEXT)
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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)
65
0 Pairs Binder Managed
60
4 Pairs Binder Managed
12 Pairs Binder Managed
Downstream Rate (Mbps)
55
0 Pairs Random Deployment
50
4 Pairs Random Deployment
12 Pairs Random Deployment
45
40
35
30
25
20
15
1000
1500
2000
2500
3000
3500
4000
4500
5000
Loop Length (ft)
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Measured Results: Downstream
Measured Data: 300 m 17A VDSL2 Downstream
(26 AWG ~= 0.4 mm 48 links in 50 pair twisted pair cable
Min Data Rate
99 Mbps (+50%)
100
90
Cable Vectoring:
48 lines (24L (rates
shown) + 24R)
in one vector group
81 Mbps (+21%)
80
70
67 Mbps
12
13
Rate (Mbps)
60
13
50
12
40
FEXT Free
30
Cable Vectoring
Binder Vectoring
20
No Vectoring
Binder Vectoring:
24 (Left) Vectored +
24 (Right) unvectored
10
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Port #
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Measured Results: Upstream
Measured Data: 300 m 17A VDSL2 Upstream
(26 AWG ~= 0.4 mm 48 links in 50 pair twisted pair cable
Cable Vectoring:
48 lines (24L (rates
shown) + 24R)
in one vector group
60
50
Min Data Rate
12
Rate (Mbps)
40
13
36 Mbps (+111%)
13
30
12
27 Mbps (+56%)
17 Mbps
20
Binder Vectoring:
24 (Left) Vectored +
24 (Right) unvectored
FEXT Free
10
Cable Vectoring
Binder Vectoring
No Vectoring
0
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
Port #
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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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DSP 3
DSP 4
DSP 1
DSP 2
DSP 3
DSP 4
DSP 1
DSP 2
DSP 3
DSP 4
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Cable Plant
DSP 2
Cable Plant
DSP 1
Cable Plant
System Level FEXT Cancellation
38
The Solution is a System Approach
Letting Everyone Join the Team
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
Crosstalk
(FEXT)
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Board Level to System Level Upgradeability
1 Cards = 48 Ports
DSL
Modem
Card 1
Binder
Card 2
DSL
Modem
2 Cards = 96 Ports
Resource
DSL
Modem
Card 3
3 Cards = 144 Ports
Card 4
4 Cards = 192 Ports
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OSP Board Level to System Level Upgradeability
Initially Single OSP has internal BLV
DSL
Modem
Binder
DSL
Modem
DSL
Modem
DSL
Modem
System level vectoring
OSPs
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41
39.3223
45.4476
47.1874
48.738
52.7167
59.0322
70.5867
35.4266
40.7892
42.2592
43.4046
46.4136
51.0869
57.3389
28.7862
33.0877
34.2689
35.1866
37.4983
40.8826
44.4597
23.9531
27.4467
28.5832
29.3747
31.2089
33.7211
35.9737
22.6768
24.5257
25.2749
25.9316
27.4054
29.2111
31.3308
19.98
21.5953
22.2604
22.7762
23.9024
25.3735
26.8474
17.0189
18.2989
18.967
19.3414
20.2696
21.484
22.5406
0
42.3628
48.6027
50.4584
52.1054
56.2349
63.3984
82.3435
10
46.0975
52.2771
54.1611
55.7737
59.8433
67.0601
91.7855
Downstream Rate (Mbps)
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)
100
90
No Pairs Removed 1%
4 Pairs Removed 1%
8 Pairs Removed 1%
80
70
12 Pairs Removed 1%
24 Pairs Removed 1%
48 Pairs Removed 1%
60
96 Pairs Removed 1%
50
40
30
20
1000
1500
2000
2500
3000
3500
4000
4500
5000
Loop Length (ft)
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Vectoring Benefits and Considerations
• Vectoring has the
potential to cancel
crosstalk in a binder:
140
• All users see rates as if
they were the only
user in the cable
– 30-50% improvement in
speed
– Reach 100Mpbs with 2
pair bonding
 Considerations
– Limited to short loops
(less than 3,000ft)
– Need system level
approach
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100
Rate (Mbps)
 Benefits
120
80
60
40
20
Upstream, 12-self crosstalk
0
500
1000
1500
2000
Reach (feet)
2500
3000
26 AWG equivalent: Multiply vectored reach by 1.3 for 24 AWG
43
Downstream Performance Full Cancellation
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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
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.
• ADTRAN knows vectoring.
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Thank You
Please visit: http://adtran.com to learn more.
Email [email protected] or call 800-9ADTRAN
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