VDSL2
and the C559 review
Paul Brooks
[email protected]
Timeline for xDSL
Max Downstream Datarate (Mbps)
50
Comparison of DSL
Technologies
45
VDSL2
40
Feb 2006-2007
35
30 initially developed by AT&T/Bell Labs in
ADSL1
25 deliver video – predates the development
1989 to
ADSL2+
20
of WWW
2003-2007
15
10
ADSL2
2002,2005-2007
5
ADSL
1999-2003
2003
ReADSL2
0
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
5
Reach (km)
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2
Why?
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3
Agenda
• DSL Redux
• ADSL 2+
• VDSL2 compared
• VDSL2+ Bandplans
• VDSL2+ benchmarks
• Bonding & Packet Transfer Mode
• DSM – Dynamic Spectrum Management
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4
ADSL2+
• 512 tones
• 25 tones upstream
• 473 tones downstream
• max ~60kbps per tone
• Frequency band up to 2.2
MHz
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VDSL2+
• Several Band-plans
• 7200+ tones (up to 30MHz)
• 3 upstream bands
• 2 or 3 downstream bands
• Same encoding and signalling
per tone - ~ 60 kbps
• Frequency band up to 12/17/30
MHz
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VDSL2 is
effectively
ADSL2+++++
6
Several Bandplans…(1)
B8-4 is a 998 plan. B7-5 is a 997 plan
50
Bit Rate (Mbps)
40
30
20
Its not as simple as
‘997 bandplans are
more symmetric,
998 bandplans are
more asymmetric…..
B8-4
B7-5
B7-5
B8-4
Assumptions:
12 MHz band plans
PIUT 40 revised
No UPBO
9 x VDSL2 equal length
10
0
0
500
1000
Length (m)
1500
2000
(Example - C559 VDSL2 working group – benchmark illustration only!)
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Several Bandplans…(2)
• G.993.2 02/2006:
• Annex A (US): 9 plans based
on ‘Annex M’ ADSL2+
• Annex B (Euro): 6 x ‘997’
plans and 7 x ‘998’ plans up to
12 MHz
• Annex C (Japan): 1 band plan
over ISDN, up to 30 MHz
• Annexes D, E, F, G, H, I, J, K
all “for further study”
But wait…there’s more…
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Several Bandplans…(3)
• G.993.2 Amendment 1
Nov 2006 draft:
•
Annex A (US): 8 downstream x 11
upstream (some not compatible with each other) =
~80 plan variations, with max at
8/12/17/30 MHz
Exercise: Pick One (1) only bandplan for use
Australia
• Annex B (Euro): 10 x ‘997’
plans and 16 x ‘998’ throughout
downstream plans up to
8/12/17/30 MHz
• Annex C (Japan): 4 minor
band plan variants, up to 30
MHz
This VDSL2 stuff is very fresh!
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Ob-Disclosure
• Communications Alliance C559
Deployment Rules Review
• Layer10 representing
Preliminary information is from
working drafts – subject to
change before publication.
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Multiple Bandplans don’t coexist
• Frequencies that one line uses for upstream,
and another line uses for downstream,
interfere and destroy each other
• Overall performance drops to lowest
common denominator for both
•Every service must use the same tones
for upstream and downstream, without
overlap
•All must use the same bandplan
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Bandplan Choice
Chosen Bandplan is
European Annex B 998
Plan B8-11 to 17 MHz
(from Amendment 1
still to be completed)
ADSL2+
Basis System
-38
-40
-51.5
-54.7
-56.2
-58.3
-60.0
Up
VDSL2(1)
Basis
System
Down
VDSL2(2)
Basis
System
VDSL2(3)
Basis
System
Not yet
defined
Down
Up
Down
Up
Down
US0 DS1a DS1b US1 DS2 US2
0.138
0.025
2.208
3.75
5.2
8.5
12
DS3
17.664
f (log scale)
• Little/No benefit to go to 30MHz, but 17 MHz provides good speed out
to ~600m
• 998 plan maximises downstream capacity for IPTV, Internet content
downloads
• Still retains good upstream (5-20 Mbps at 800m) – upstream capacity
meets or beats eSHDSL symmetric services at all distances
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VDSL2 Deployment Classes
ADSL2+ Deployment Classes
VDSL2 Deployment Classes
•
•
•
•
6h = ADSL2+ (Annex A)
(unlimited distance)
6j = ADSL2+ Annex M EU-40
•
•
6k = ADSL2+ Annex M EU-52
•
6l = ADSL2+ Annex M EU-56
•
6m = ADSL2+ Annex M EU-60
•
6n = ADSL2+ Annex M EU-64
•
•
•
10h = VDSL2
10j = VDSL2 +Annex M EU-40 in
US0 upstream
10k = VDSL2 +Annex M EU-52 in
US0 upstream
10l = VDSL2 +Annex M EU-56 in
US0 upstream
10m = VDSL2 +Annex M EU-60 in
US0 upstream
10n = VDSL2 +Annex M EU-64 in
US0 upstream
NOT any of the further ‘Annex M-like’
EU-XX beyond EU-64
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VDSL2+ Benchmarks
Benchmark: 10h modelled worst-case performance
ADSL2+ vs VDSL2 Upstream Benchmarks
18
Downstream Datarate (Mbps)
VDSL2 upstream
benchmark (800m ref)
ADSL2+ upstream
benchmark
20
Downstream Datarate (Mbps)
ADSL2+ vs VDSL2 Downstream Benchmarks
16
14
12
10
VDSL2 Benchmark
70
65
60
55
50
45
40
35
30
25
20
15
10
5
0
ACIF Benchmark
Preliminary Only – Do Not Rely On These!
8
6
4
2
0
0
0.5
1
1.5
2
2.5
0
0.5
1
1.5
2
2.5
Reach (km)
Reach (km)
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/end C559
Back to ITU-T G.993.2…
(but still subject to amendments!)
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Other VDSL2 tricks
• Bonding
• 2 – 8 parallel VDSL2 services together, acting as a single
channel (needs compatible CPE)
• 80 Mbps upstream, 640 Mbps downstream anyone? 
• Packet Transfer Mode (PTM)
• Ethernet-in-the-first-mile (EFM) 802.3ah framing is
supported natively
• no more fiddling with ATM PVCs in the DSLAM or modem
required
• ~ 5% increased performance from reduced overheads
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DSM
Dynamic Spectrum Management
• Adjusts transmit power in each line to time-variable external
crosstalk, to optimise bandwidth for all lines in the binder by
reducing cross-talk
• No DSM (current situation) – assumes each line is greedy –
worst-case modelling leads to conservative performance
• DSM Level 1 – static spectrum shaping to avoid crosstalk –
each line tries to optimise PSD shape and be polite in isolation
• DSM Level 2 – dynamic spectrum shaping – each line talks to
neighbours and all optimise PSD to try to be polite
• DSM Level 3 – MIMO cross-talk cancellation – reverse crosstalk
signal calculated and added in real-time to cancel out at the
far end
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DSM Level 2
• Algorithms developed fairly recently
•
•
•
•
Iterative Water-Filling (2002)
Optimal Spectrum Balancing (2004)
Iterative Spectrum Balancing (2005)
Autonomous Spectrum Balancing (2006)
• Not available from DSLAM vendors currently,
although some are preparing products and
management systems to support DSM.
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DSM Level 2
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DSM Level 3
• Full MIMO Crosstalk Cancellation
• Ask Dr John Papandriopoulos…in about 3 – 5
years…
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Wrapup
“Its easy to offer 50Mbps access lines, if you
know the top 40 Mbps will never be able to be
used” Me.
• Great access network speeds are one thing – be
careful the backhaul can feed the access – or
there is local-enough content to avoid using the
backhaul
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VDSL2 wont solve everything
• Some problems will be made worse by VDSL2
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Thank you
[email protected]
www.layer10.com.au