COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED. G.fast – Shifting the limits of copper Bell Labs, Alcatel-Lucent - Jochen Maes 19 January, 2012 @ UKNOF
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
G.fast – Shifting the limits of copperBell Labs, Alcatel-Lucent - Jochen Maes 19 January, 2012 @ UKNOF
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
2
…
…
FTTH - the next big thing for decades …
1988
1988
1989
1988
1988
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
3
Reality gradual deployment of fiber deeper in network
CO deployment Fiber to the Curb / Distribution Point
Fiber to the Node / Cabinet
CO cross-connect cabinet
CO mini DSLAM
CO micro node
<5km, 24 Mb/s <1km, 100 Mb/s <200m, 1 Gb/s
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
4
Shifting the limits of copperPON
The Gap
1 Mbps
10 Mbps
100 Mbps
1 Gbps
50 Mbps
500 Mbps
5 Mbps
1995 2000 2005 2010 2020-2030
ADSL
ADSL2ADSL2+
VDSL(2) 8b
VDSL2 17a+ bonding
+ vectoring
+ Phantom
+ G.fast
Copper innovations allow operators to gradually build up their fiber network
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5
Vectoring
0
20
40
60
80
100
120
100 200 300 400 500 600 700 800 900 1000 1100 1200
Optimal VDSL2 performance
Reduced field performance due to crosstalk
+150%
Loop length / distance (m)
Ban
dwid
th (
Mbp
s)
Near-optimal field performance with vectoring
+a
-a
+c
-c
+b
-b
+c+a
+c-a
+c
-c–c+b
–c-b
Customer modem
DSLAM
voltage
virtual pair
virtual ‘plus’
virtual ‘minus’
0100200
300400500600700
800900
1000
Sing
le li
ne
Bon
ding
Vec
tore
dPh
anto
m
Phan
tom
on
Phan
tom
Phantom modeD
ata
rate
(M
b/s)
Loop length (m)D
ata
rate
(M
b/s)
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
6
ITU project G.fast
• Standardizing copper physical layer aspects of FTTdp
• Initiated February 2011
• Earliest opportunity for consent: e.o. 2012• Means, earliest, standard could be approved in 2013; products could be available in 2014
• Contributions by DSL and G.hn vendors
• Main requirements• High peak data rate, e.g. 500 Mb/s at 100 m
• Suited for reverse powering
• Allowing for customer self-install
• Optimized for short loops - not a substitute for FTTCab
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7
G.fast is becoming technologically feasible
Timmers et al., proceedings of Access2011
Digital computation complexity relative to ADSL in 2001
Along x-axis, cost of complexity is scaled with Moore’s law
Technologically feasible – analog will be limiting design factor
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8
FTTdp architecture
CO
Passive splitter
RE CPE
G.fasttransceiver
Powerextraction
Powerinsertion
G.fasttransceiver
Powersource
RE power supply unit
60 VdcRE CPE
CPE powered network equipment
Up to 1 Gb/s net rate
8-24 users per remote network equipmentFits within TR-156 and TR-167 deployment model
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
9
0 50 100 150 200 250 300 350 4000
2
4
6
8
10
12
14
16
18
20
Loop length (m)
Load
pow
er (W
)
0.9 mm Cu at 20°C0.5 mm Cu at 20°C0.4 mm Cu at 20°C0.4 mm Cu at 65°C0.4 mm Al at 65°C
Reverse power feed power transfer capability
ETSI TR 102 629 : Reverse Power Feed for Remote Nodes
Source voltage 60 V, within SELV limit, current < 300 m
System design for worst case – when single long line is connected
COPYRIGHT © 2011 ALCATEL-LUCENT. ALL RIGHTS RESERVED.
10
0 50 100 150 200 250 300 350 4000
0.5
1
1.5
2
2.5
3
3.5
4
Tim
e (µ
s)
Loop length (m)
Arrival delayExcess delayTotal delay
Time division duplexing
• Advantages of TDD:• Reduction in analog complexity
• Increases transmission efficiency
• Halves the modulation complexity
• Starting frequency above VDSL2, for legacy compatibility
Req
uir
ed C
E in
FD
D
CE
in T
DD
TDD allows relaxing analog requirements
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11
P2P and P2MP system architecture
Switchfunction
Tx filter
Rx filter
LD
amp
DAC
ADC
LD
amp
LD
amp
Control function
G.fastDSP
1 Gb/s aggregation
Tx filter
Rx filter
LD
amp
DAC
ADC
LD
amp
LD
amp
G.fastDSP
Several Gb/s aggregation
Tx filter
Rx filter
DAC
ADC
Tx filter
Rx filter
DAC
ADC
Point-to-multipoint with TDMA MACAnalogy with cable
Point-to-point
Options under consideration in ITU G.fast
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12
UK Reference loops P2MP vs. P2P comparison
0 10 20 30 40 50 60 70 80 90 100-50
-45
-40
-35
-30
-25
-20
-15
-10
-5
0
Frequency (MHz)
Hlo
g (d
B)
D1H1D2H2D2H1D3H5D4H5D4H3
D1-H1 D2-H2 D2-H1 D3-H5 D4-H5 D4-H3Loop length 176.1 m 137.1 m 113.1 m 45.6 m 83.3 m 93.3 m2.2 MHz 740 642 1076 1270 1084 92212 MHz 616 541 944 1138 953 80517.7 MHz 552 493 868 1062 876 73430 MHz 428 384 714 895 720 599
UK reference loops
2 4 6 8 10 12 14 16 180
50
100
150
200
250
Node size
Net
sus
tain
able
BH
OL
(Mb/
s)
2.2 MHz12 MHz17.7 MHz30 MHz
P2P rate (vectored)
Average TDMA rate of N-1 users if 1 user is at 500 Mb/s ‘peak rate’
Start frequency
Key question: ‘up to’ or ‘guaranteed’ bandwidth
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13
Transmitter Controlled Adaptive Modulation
Operator benefit:
• Robustness Self-install
• Spectral efficiency Throughput
• Green Reverse powering
With minimal implementation impact11 11
01 11
11 01
01 01
00 11
10 11
00 01
10 01
00 00
10 00
00 10
10 10
11 00
01 00
11 10
01 101 1
0 1
1 0
0 0
Traffic drivenpower control
Noise drivengrid control
Automatic adaptation to traffic load and channel conditions
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14
CuGAR Copper Gigabit Access Research evaluation platform
SERVER
D6 LAB
FPGA Front end
cable
FPGA
Front end
remote connection
off-line connection
real-time connection
place and
route
Bit
load
ing
Test bed for candidate technologies
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FTTdp - G.fast
• Continued copper access innovations facilitate operators to spread fiber investments
• G.fast is targeted for short loops up to 200 m from the last distribution point
• Being standardized in ITU-T, promising up to 1 Gb/s
• Transmitter controlled adaptive modulation is proposed, enabling high throughput, self-install and reverse powering
• P2P and P2MP system architectures under study in ITU
• TDMA offers high peak rate, but lower sustainable rate applied to UK reference loops – behaves like cable or PON