dynamic spectrum management ( 1000m x 1000m)
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Dynamic Spectrum ManagementDynamic Spectrum Management((1000M x 1000M)1000M x 1000M)
IEEE SCV Communications Society October 12, 2005
Speaker: J. CioffiStanford University (M. Mohseni, V. Pourahmad, M. Brady)
cioffi@stanford.edu
Special Thanks to: ASSIA Inc (Wonjong Rhee, I. Almandoz , G. Ginis, P. Silverman) SBC Network Systems Engineering (R. Savoor, S. Sposato)France Telecom (R&D) (H. Mariotte, M. Ouziff, F. Gauthier)British Telecom (K. Foster, J. Cook)Deutche Telekom T-Systems (S. Symalia, E. Berndt, J. Buhl)Alcatel Bell (DSM Research Group)Telcordia (K. Kerpez & D. Waring)
2
Automated Maintenance (=DSM)
• OPS = Majority of DSL effort• Reduce through electronic
management of– Provisioning– Maintenance– Qualification– Capacity (rate/range)
• Reduce “truck rolls” and improve overall ADSL performance– Permits higher speeds further
70+ %30- %
DSL "Effort" Equipment
Operations
3
Two DSM (“adaptive”) Steps
1. DON’T “HOG”• (Each line uses minimum power)
• Adaptive Spectrum
2. Cooperate• Signal Alignment
4
Outline
• Step One (Adaptive Spectra)– Margin/Rate management– Impulse/code management
• Step Two (Signal Alignment)
5
DSM System Diagram
• Accepts data• Processes data• Provides recommendations
FiberFiber
DLCDLCRTRT
ADSL
H or VDSL
ADSL
ADSL
cable
CO
DSLAM
RT+
CLEC
DSM CENTERDSM CENTER
ILEC
MonitorMonitor
ProvisionProvision
MaintainMaintain
MonitorMonitor
ProvisionProvision
MaintainMaintain
6
DSM Data (to DSM Center)
1) ADSL1• Margins, powers, rates, bit table, code
violations • Current and max data rates
2) Web Pages / ADSL2 (WT87)• Attenuation[n], Noise[n]
3) Loop “Make-Up” Report• Lines at same service terminal (same and nearby binders)• Common lengths (taper codes), bridged taps, total length
I/CLEC
DSM CENTERDSM CENTER
MonitorMonitor H or VDSL
ADSLcable
CO
DSLAM(EMS)
7
DSM Controls (from DSM Center)
I/CLEC
DSM CENTERDSM CENTER
MonitorMonitor H or VDSL
ADSL
cable
CO
DSLAM(EMS)
• Maxrate VECTOR
– Maxrate[1] (present conditions)
– Maxrate[2] = Difficult conditions
– Maxrate[3] = Other DSLs doing DSM
– Each may have different profile
• Profile Recommendation
– Rates/Margins
– Code Choices
[3]
[3]
[1]
[2]
Data rate
[0] = current rate
8
DSL Subscriber (Initially 384 kbps)
• 13.6 kft, currently at 384 kbps– Own power use (904 kbps)– Polite fiber-fed terminals (each held at 1.536
Mbps)
DSM Use - Mixed (RT/DSLAM) Binder
0
200
400
600
800
1000
1200
1400
1600
1800
2000
current full power Polite RTs
Power Usage
Dat
a R
ate
(kb
ps
)
Series1
RT/DSLAM Mix Victim
0
1
2
3
4
5
6
7
8
1 14 27 40 53 66 79 92 105 118 131 144 157 170 183 196 209 222 235 248
tone index
bit
s/to
ne
9
DSM Multi-user Rate REGIONS
• Plot of all possible rates of users– any point is possible
• More than 2 users (vector of possible rate-tuples)• Fear of “hogs” forces the small area to be used
– With worst-case FIXED models currently applied
RRlonglong
RRshortshort
SpectralSpectral pair 1pair 1
Spectral pair 2Spectral pair 2
Current “static spectrum management”Current “static spectrum management”
10
What is Politeness (Near/Far) ? (near transmitter “speaks softly” – transmits only power it needs)
RTRT
NEARNEAR
FARFARCOCO
Downstream Example
Upstream Example
LTLTNEARNEAR
FARFAR
11
Telcordia DSM-ADSL Rate Regions [T1E1.4/2002-063]
lines 1 & 3 (2 held at 1.6 Mbps)lines 1 & 3 (2 held at 1.6 Mbps) lines 1 & 2 (3 removed) – 063R1lines 1 & 2 (3 removed) – 063R1
• Nominal 15 kft data rate without DSM– 300 kbps
A AA A
Fiber, 10 kft
5 kft
Copper, 15 kft
A15 kft
Nominal 300 kbpsNominal 300 kbps
12
Higher Speeds? Symmetric? (yes with DSM)
• No coordination yet (but no hogging allowed)• No effect on existing ADSL if implemented with DSM• How did we do this???
13
Carrier A and DSM, CO/RT (ASSIA)
14
ADDNMR = Iterative Water-Fill• Minimize Power (at some max margin)
– Diagram on right below
• No coordination of modems– Service provider sets Rate & ADNMR
• “Adaptive Spectrum”
NSR(f)NSR(f)
S(f)S(f)
NSR(f)NSR(f)
S(f)S(f)
“HOG” (margin = 30 dB) POLITE (margin << 30 dB)
15
DSLAM to CPE
• Margins > 16 dB to 10 kft.– Despite promise by vendors that 16 dB would not be exceeded
• CPE Problem? – (no, CPE, DSLAM, and ITU standards all share in fault)
Measured Noise Margin (CURNMR) Comparison
05
101520253035
1000
3000
4000
5000
6000
8000
1000
0
1100
0
1300
0
1500
0
Loop Length, kft
No
ise
Mar
gin
, d
BAlcatel Speed TouchRA MAXNMR10
Efficient 5100 RAMAXNMR10
Westell MH RAMAXNMR10
Efficient 5100 RAPower BackOffMAXNMR10
2Wire Router
Modem 1Modem 1
Modem 2Modem 2
Modem 3Modem 3
Modem 4Modem 4
Modem 5Modem 5
16
Another Vendor Issue – “Virtual Noise”
• Telco sets a worst-case noise– Often wrong or not possible– Undue conservative (opposite of politeness)
17
Use of VN Upstream VDSL near/far
0 2 4 6 8 10 12 14 16 18 200
1
2
3
4
5
6
7
8
600 m. Lines
900
m.
Line
s
IW vs. VN, where VN = "noise seen in IW +10dB"
VN
IW
0 2 4 6 8 10 12 14 16 18 200
1
2
3
4
5
6
7
8
600 m. Lines90
0 m
. Li
nes
IW vs. Mixed IW/VN
IW
VN/IW
Same ILEC all lines Unbundled
VNVN
Politeness (IW)Politeness (IW)
18
Outline
• Step One (Adaptive Spectra)– Margin/Rate management– Impulse/code management
• Step Two (Signal Alignment)
19
A General Finding from FT work• Use erasures and lower-rate RS codes
– When code/CRC violations found– Use normal settings of (240,224) when no CRC violations
(i.e., no impulses)
20
Steps to take?
• Ask subscriber modem vendors for– Max-impulse protection option– Invoked by DSM Center when CRC or FEC violations noted– Almost in G.997.1 parameters (need > 500 s)
DSM CenterDSM CenterCenterCenter DSLAMDSLAM SubscriberSubscriber
ADSLADSL
Max impulse mode
CRC Violations
21
Live Subscriber – Bad Impulse
• 10 kft 26-gauge• Intermittant noise, 0-400 kHz• Code Violations even with
nominal “interleave” setting– 768 kbps– 28 dB DS margin, but CVs– 19 dB US margin, but CVs
• After DSM : > 3 Mbps– Uses 48,32 FEC
Bad Impulse House
0
0.5
1
1.5
2
2.5
3
3.5
4
4.5
1 14 27 40 53 66 79 92 105 118 131 144 157 170 183 196 209 222 235 248
tone index
bit
s/t
on
eCode Violations - 15 min
0
500
1000
1500
2000
2500
3000
3500
1 3 5 7 9 11 13 15 17 19 21 23 25 27 29 31 33
15-min Interval
CR
C V
iola
tio
ns
22
Carrier C and DSM: Advanced INP
23
Cioffi DSL Line 1
• 17000’ loop• Provisioned at 192 kbps, now running 768 kbps with early DSM
NoiseNoise(also impulse(also impulsenot shown)not shown)
Insertion lossInsertion loss
24
Cioffi DSL Line 2
• 8000’ loop (fiber-fed “remote terminal” RT)• Provisioned at 1536 kbps, now running 6008 kbps with early DSM
ADSL FEXT region
1500’ bridged-tap
Noise
AM radio
Insertion loss
NoiseNoise(also impulse(also impulsenot shown)not shown)
25
Outline
• Step One (Adaptive Spectra)– Margin/Rate management– Impulse/code management
• Step Two (Signal Alignment)
26
Bonding ≠ Vectoring
• Bonding– Use N lines to get N x the data rate
• Possible to vector also, but bonding does not force use of vectoring
– Mux and inverse Mux
• Vectoring– Cogenerate at PHY level signals and/or– Coreceive at PHY level signals– Can do one-sided without bonding– Can do one/two-sided with vectoring
27
STEP TWO – “Vectoring”(Signal Alignment)
20-100 Mbps20-100 Mbps(symmetric)(symmetric)
CentralOffice
ILEC LT/RT
Switchrouter
FIBER
twisted pair
DSLAM
DSM
bbiinnddeerr
• Note Fiber to RT or LT
DSM
28
Upstream – Multiple Access (per tone)
• One for each tone• Lines synchronized and digitally duplexed• 3rd generation vectored DSLAM• Works as if No NEXT or FEXT present
Wn=Q’n++
YZ
X1,nG1,n
X2,nG2,n
.
.
.
XL,nGL,n
Hn=QnRnn(Loop)
dec
Bn=Rn
Feedback orPacket detector
One One sideside
29
Downstream Broadcast (per tone)
Q’n++
Y
Z1,nD1,n
Z2,nD2,n
.
.
.
ZL,nDL,n
mod
Bn=Rn
Feedback orPacket precoder
Xn,i
Hn=RnQnn
()
• One for each tone
• Lines synchronized and digitally duplexed
• 3rd generation DSLAM
• Works as if no FEXT present
One One sideside
30
T-Systems (German -DT) ResultsVDSL with SHDSL (I)
31
German results for VDSL with HDB3 (III)
32
Symmetric Rates – AS (green) vs SIA (blue)
• Increases data rates at all lengths with Vectored DSLAM• Power can be lowered – possible to do 10 dBm or less• 100 Mbps (single line, no bonding) at 1500 ft symmetric, 2500 ft
asymmetric• Cioffi’s 17 kft loop to 2.5 Mbps (256 kbps up) !
33
Ultimate Result of Vectoring
• Distribution Area to 100 Mbps single line
• 1000M x 100 Mbps– Getting closer to the goal
34
The Wireless Power Co ?
• Hmmm ……..– Lots of antenna’s needed for 100 Mbps (both sides)– Lots of power for 100 meters or more also– Perhaps high-speed wireless LAN stays at end of
DSL (like today)?
35
GDSL?• Pedestal drop
– <300 meters– 2 to 6 lines
typical– Xtalk is self
• Last few 100 meters is $$$ for fiber
GDSLGDSL
36
Split-pairs/”phantoms”7766
5544
3322
1100
There are actually 7 independent channels in those 4 loopsThere are actually 7 independent channels in those 4 loopsall 7 have high capacityall 7 have high capacity
Well over 1000 Mbps at 300 meters (category 3)Well over 1000 Mbps at 300 meters (category 3)
Vector 7x7 channelVector 7x7 channelPedestal drop DSL – how fast?Pedestal drop DSL – how fast?
37
Matrix Matched LoadVs(7)
Zs Z0
Vs(6)
Vs(5)
Vs(4)
Vs(3)
Vs(2)
Vs(1)
ZLZL
• Resistor across all 7 possibilities
38
Some Results (symmetric FDM)
39
DSM• DON’T “HOG”
– Adaptive Spectrum– 100M x 10M
2. Cooperate• Signal Alignment• 1000M x 100M
100 M100 M
3. GIGABIT DSL (GDSL)• 1000M x 1000M GGDSLDSL
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