1 DSM DSM Dynamic Spectrum Dynamic Spectrum Management Management John M. Cioffi John M. Cioffi Prof. EE, Stanford U. Prof. EE, Stanford U. [email protected][email protected]And all the work by And all the work by students: students: Taek Chung, George Ginis, Taek Chung, George Ginis, Jeannie Fang, Jungwon Lee, Jeannie Fang, Jungwon Lee, Dimitris Toumpakaris, & Wei Dimitris Toumpakaris, & Wei Yu Yu July 2002 July 2002
Dynamic Spectrum Management. July 2002. John M. Cioffi Prof. EE, Stanford U. [email protected] And all the work by students: Taek Chung, George Ginis, Jeannie Fang, Jungwon Lee, Dimitris Toumpakaris, & Wei Yu. Copper has more bw than fiber?. fiber. - PowerPoint PPT Presentation
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And all the work by students:And all the work by students:
Taek Chung, George Ginis, Jeannie Taek Chung, George Ginis, Jeannie Fang, Jungwon Lee, Dimitris Fang, Jungwon Lee, Dimitris
Toumpakaris, & Wei YuToumpakaris, & Wei Yu
July 2002July 2002
2 DSMDSM
Copper has more bw than fiber?Copper has more bw than fiber?
DSL will deliver 100 Mbps symmetric to allDSL will deliver 100 Mbps symmetric to all 50 line bundle (500 meters of cat 3 tp)50 line bundle (500 meters of cat 3 tp)
50 lines (100 Mbps/line) = 5 Gbps 50 lines (100 Mbps/line) = 5 Gbps FTTH shares 622 Mbps among 50 or more homes in FTTH shares 622 Mbps among 50 or more homes in
PON architecture (even “future” systems are 2.5 Gbps)PON architecture (even “future” systems are 2.5 Gbps) So, where is DSL today?So, where is DSL today?
Where is DSL going?Where is DSL going?
fiberfiber
Cable of copper pairCable of copper pair
3 DSMDSM
DSL 200DSL 200XX- (V/M/ADSL)- (V/M/ADSL)
Data , Voice , Video …Data , Voice , Video …
802.11 wireless (802.11,15) orwireless (802.11,15) orother distribution possibleother distribution possiblewithin CPE, 11, 55,within CPE, 11, 55,100-500 Mbps100-500 Mbps
Standard in progress – USA (ANSI / T1E1.4)Standard in progress – USA (ANSI / T1E1.4) Dynamic – loops, xtalk, rates veryDynamic – loops, xtalk, rates very
Not limited by worst-case static situationsNot limited by worst-case static situations Extension to existing Spec ManagementExtension to existing Spec Management
T1.417-2002T1.417-2002 Improve considerably reliability and performanceImprove considerably reliability and performance Cannot have spectrum compatibility at higher speeds without DSMCannot have spectrum compatibility at higher speeds without DSM
Crosstalk effect is too strong for static regulationCrosstalk effect is too strong for static regulation THIS IS A CRUCIAL turning point for DSLTHIS IS A CRUCIAL turning point for DSL
Goals: 100 Mbps symmetric everywhereGoals: 100 Mbps symmetric everywhere & Improve the range of every rate < 100 Mbps& Improve the range of every rate < 100 Mbps
SM (static)SM (static) VDSLVDSL10MDSL10MDSL
ADSL+ADSL+ 100MDSL100MDSL
VDSL-2VDSL-2
DSMDSMHDSL / ADSLHDSL / ADSL
20002000 20012001 20022002 20032003
……
““EFM”EFM”
5 DSMDSM
OutlineOutline
Crosstalk and ManagementCrosstalk and Management Autonomous (de-regulated) DSLAutonomous (de-regulated) DSL Bonded/Vectored DSLBonded/Vectored DSL
Same service provider Same service provider Different service providerDifferent service provider Management?Management?
Spectrum – fixed or staticSpectrum – fixed or static Ok, but performance and reliability severely Ok, but performance and reliability severely
compromisedcompromised
Symmetric versus asymmetricSymmetric versus asymmetric
PhonePhoneCo=BaseCo=Base(DSLAM)(DSLAM)
useruser
useruserNEXTNEXT
FEXTFEXT
7 DSMDSM
Some CrosstalkSome Crosstalk
105
106
107
108
20
25
30
35
40
45
50
55
60
65
Freq (MHz)
cros
stal
k co
uplin
g (d
B)
NEXT - BellcoreNEXT - Bellcore(attenuation)(attenuation)
FEXT Plots
-90
-80
-70
-60
-50
-40
-30
-20
-10
0
10000 100000 1000000 10000000
Frequency (Hz)
Lev
el (
dB
) FEXT 1
FEXT 2
FEXT 3
FEXT 4
FEXT – British FEXT – British TelecomTelecom(gain)(gain)
Xtalk noise increases with frequencyXtalk noise increases with frequency
8 DSMDSM
Loop TopologyLoop Topology
Many other configurationsMany other configurations symmetric/asymmetric mixturessymmetric/asymmetric mixtures Data rate mixturesData rate mixtures Shorter linesShorter lines Bonding of linesBonding of lines
CO DSLsCO DSLs
CPECPE DSL DSL
CPECPE DSL DSL
CO DSLCO DSL CPECPE DSL DSL
LT DSLLT DSLCPECPE DSL DSL
9 DSMDSM
ADSL DMT Loading BasicsADSL DMT Loading Basics(adapts to each line)(adapts to each line)
FrequencyFrequency
FrequencyFrequency
AttenAtten
TWISTED-PAIRTWISTED-PAIR
Bits/chanBits/chan
FrequencyFrequency
Bits/chanBits/chan
FrequencyFrequency
FrequencyFrequency
AttenAtten
TWISTED-PAIR with TAP, AM/RF, and XTALKTWISTED-PAIR with TAP, AM/RF, and XTALK
AMAM
xtalkxtalk
Bits/chanBits/chan
FrequencyFrequency
Bits/chanBits/chan
800 Million phone lines and growing fast!800 Million phone lines and growing fast!
Crosstalk between users is “matrix channel”Crosstalk between users is “matrix channel” ““Interference channel” in information theoryInterference channel” in information theory
Can users be compatible without large loss? (SSM – Can users be compatible without large loss? (SSM – no, DSM - yes)no, DSM - yes)
......
SharedSharedbinderbinderHH(f)(f)
DSL 1DSL 1
DSL KDSL K
DSL 2DSL 2
DSL KDSL K
DSL 1DSL 1
DSL 2DSL 2
13 DSMDSM
DSM Multi-user Rate REGIONSDSM Multi-user Rate REGIONS
Plot of all possible rates of usersPlot of all possible rates of users ADSL & some VDSL use DSM – any point is possibleADSL & some VDSL use DSM – any point is possible
More than 2 users (vector of possible rate-tuples)More than 2 users (vector of possible rate-tuples) Region’s size (volume) can vary with:Region’s size (volume) can vary with:
each bindereach binder transmission methods (i.e., DMT has much larger regions)transmission methods (i.e., DMT has much larger regions)
CLASSIC field problem with ADSL present-day deploymentsCLASSIC field problem with ADSL present-day deployments Long-line often does not work and field personal have to be dispatchedLong-line often does not work and field personal have to be dispatched
Improve the performance of line 1 AUTONOMOUSLY (no coordination) using DSM-mode in ADSL modemsImprove the performance of line 1 AUTONOMOUSLY (no coordination) using DSM-mode in ADSL modems Eliminate problem automaticallyEliminate problem automatically Greatly extend ADSL rangeGreatly extend ADSL range
ADSLADSLrcvrrcvrfiber
15 DSMDSM
InitialInitialShort-line spectra,Short-line spectra,Long-line turns onLong-line turns on
DSM ADSL basic spectrum result
Short-line spectraShort-line spectra
LongLongLineLine
spectraspectra f
Downstream Spectra (2 lines)
Short line yields to long No “DSL hogging”
Enormous improvement on long line At expense of reduced rate on short line
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
No coordination (line 2 held at 6 dB margin, 1.6 MbpsNo coordination (line 2 held at 6 dB margin, 1.6 Mbps 4x improvement on Line 1 (was at 300 kbps if line 2 does 4x improvement on Line 1 (was at 300 kbps if line 2 does
RA or margin-max training) – like “Verizon” expt.RA or margin-max training) – like “Verizon” expt. 4x because 15kft, not 20 kft like Verizon4x because 15kft, not 20 kft like Verizon
Water-filling is known optimum on single-user channelWater-filling is known optimum on single-user channel Use DMT, and MINIMIZE POWER for given rate/marginUse DMT, and MINIMIZE POWER for given rate/margin
Best autonomous solution to “interference problem” in binderBest autonomous solution to “interference problem” in binder The more lines that do DSM, the better they all workThe more lines that do DSM, the better they all work
NEVER any worse than existing fixed/static Spectrum ManagementNEVER any worse than existing fixed/static Spectrum Management AUTONOMOUS – no coorination necessary, procedure assures overall best mutual spectra (least AUTONOMOUS – no coorination necessary, procedure assures overall best mutual spectra (least
harmful xtalk) of all DSLS in distributed fashionharmful xtalk) of all DSLS in distributed fashion
22 DSMDSM
3-steps to Broadband DSL3-steps to Broadband DSL
DSMDSM ADSL -Software option in current ADSL modemsADSL -Software option in current ADSL modems ADSL+ & 10M-DSL (DMT only) – iterative wfADSL+ & 10M-DSL (DMT only) – iterative wf 100M-DSL (DMT only) 100M-DSL (DMT only)
25 10MDSLs in same binder (same length)25 10MDSLs in same binder (same length)
No coordination No coordination 10 Mbps single-line range is 2.5x SSM result (SHDSL)10 Mbps single-line range is 2.5x SSM result (SHDSL) 10 Mbps >1.5 km on 2 lines10 Mbps >1.5 km on 2 lines
VerifiedVerifiedByBy
TelcordiaTelcordia
VerifiedVerifiedByBy
VoyanVoyan
25 DSMDSM
Example PSD for 4000’Example PSD for 4000’
Overlap (EC) to 800 kHzOverlap (EC) to 800 kHz Each has 3 basic bandsEach has 3 basic bands
26 DSMDSM
MDSL with ADSL presentMDSL with ADSL present
Range of ADSL and of MDSL Range of ADSL and of MDSL unaffected if DSM is usedunaffected if DSM is used Not true for Static SM (or SHDSL)Not true for Static SM (or SHDSL)
27 DSMDSM
ADSL at CO, MDSL at RT ADSL at CO, MDSL at RT
Cabinet is 10 kft from CO – last 2 to 6 kft in same binderCabinet is 10 kft from CO – last 2 to 6 kft in same binder ADSL at CO “swamped” by 64 PAMADSL at CO “swamped” by 64 PAM ADSL at CO largely unaffected by IWADSL at CO largely unaffected by IW
Allows mixture of ADSL with MDSL, and VDSL with MDSLAllows mixture of ADSL with MDSL, and VDSL with MDSL Rate regions do reduce in size for VDSLRate regions do reduce in size for VDSL
But all VDSL and MDSL goals still exceededBut all VDSL and MDSL goals still exceeded
Table 2 – Augmentation of Table 1 with IW resultsTable 2 – Augmentation of Table 1 with IW results
Aggregate bit Aggregate bit rate (sym rate (sym payload)payload)
# of # of twisted twisted pairspairs
Average bit rate Average bit rate per pairper pair
No DSL modem should use more No DSL modem should use more transmit power than it needstransmit power than it needs
No DSL modem should use more No DSL modem should use more bandwidth than it needsbandwidth than it needs
Can be solved adaptively and Can be solved adaptively and autonomouslyautonomously Stop proliferating DSL standards and Stop proliferating DSL standards and
Use/Extend ADSL DMT Frequency GridUse/Extend ADSL DMT Frequency Grid Already on 24 million lines (> 95% of market)Already on 24 million lines (> 95% of market)
ADSL+ = 512 tones down / 128 upADSL+ = 512 tones down / 128 up 10MDSL= 1024 tones down/1024 up10MDSL= 1024 tones down/1024 up VDSL = 2048 up/downVDSL = 2048 up/down 100MDSL 4096 up/down100MDSL 4096 up/down
DSM Spectrum Plan
010002000300040005000
ADSL
ADSL+
10M
DSL
VDSL
100M
DSL
DSL Type
Nu
mb
er o
f to
nes
Down
Up
33 DSMDSM
OutlineOutline
Crosstalk and ManagementCrosstalk and Management Autonomous (de-regulated) DSLAutonomous (de-regulated) DSL Bonded/Vectored DSLBonded/Vectored DSL
““broadcastbroadcast” and “” and “multiple-accessmultiple-access” probs in IT” probs in IT One-sided vectoring, FDM of up/downOne-sided vectoring, FDM of up/down
Bonding (vector broadcast and vector MA problems in IT)Bonding (vector broadcast and vector MA problems in IT)