TDSL 1 !

!

TerabitDSL(TDSL)(Useofacopperpair’ssub-millimeter

Waveguidemodes)

G.fastConferenceParis,May10,2017

J.CioffiProfessor

Emeritus,StanfordEE

(CEO/COBASSIA)

K.KerpezSr.Director,StandardsASSIAInc.

ChanSooHwangSr.DirectorR&D

ASSIAInc.

IoannisKanellakopoulosConsulIngCTO

ASSIAInc.

plasmonpolaritonsCouirtesy:BilkentU

TDSL 2 !

DriversforHigher-SpeedDSLs

•  MULTITUDEof5Gsmallercells–  high-speedlow-latencywiredsupport–  New5G-fibercost=400Beuros(foreurope,DTCTO,2016)

•  FibertheoreWcalcapacity~500Tbps–  Todaysupports1Gbpsto100Gbps(access-network)

•  BUT–  INSTALLcosts$3000-$4000/home(average)

•  $4trillionglobally(insteadpaynaWonaldebts?)–  Successfulbusinesscaseneeds<1/10ofthiscost

•  Thecoppertwistedpairsarethere(1.3B)–  Runfiberpartoftheway($3000/10homesisabe`erbusinesscase)–  ConWnuesxinxDSL,socanx=T?

Ovum 2015

Yes,wethinkso

ADSL (G.992.1, G.992.3)

Bandwidth (bps)

Reach

Vectored VDSL G.993.5

VDSL2 (G.993.2)

ADSL2+ (G.992.5) 2001

2003

2007

2014

6Km 3Km 1500m 500m 200m

1G

500M

100M

50M

20M

8M

1M

FTTEx FTTC/B FTTdp

Telco CO

ONU/LT (ends fiber Starts copper)

xDSL fiber

xDSL

G.MGFast 10G

50m

G.Fast G.9902

2018+

CurrentxDSLprogression

TDSL?

TDSL 4 !

Vectoring=1stMassive(MU-)MIMO(2001invenWon/introtostandards)

•  MassiveantennasàvecDSLAM•  Purple“ChannelHardening”àcopperpairs

–  Thosearethewireswithcrosstalkcanceled–  ThenMu-MIMO/vectoringagainWi-Fitodevicefromgateway!

•  Itisindeedthesamesignalprocessing–  DiagonaldominanceofDSL~channelhardening

•  Useoflinearprecoderinsteadofnon-linear(uptoapoint)•  MaybewecanborrowbackabitfromMassiveMIMO’smmW?

TDSL 5 !

MIMO?àIt’sreallyMISO(orSIMO)

•  IninformaWontheory–single-sidedcoordinaWon–  Downstream=vectorbroadcastchannel(MISO)–  Upstream=vectormulWple-accesschannel(SIMO)–  It’swhytheterm“vectoringwasused”(notMISO/SIMO/MIMO)

•  MIMOcoordinatesBOTHends–  Solotsofantennas/wiresatreceivesideinsameplace–  Someearly“H”DSL(Voyan)didthis–  Butnotphysicallypossiblewhenthehomesareindifferentplaces

TDSL 6 !

TwoTDSLPaths:mulWpair&singlepair

6

TDSL

MulW

easier/convenWonal

BondmanyPairs

forcellsite,maybe

Single

harder-useTM/TEmodes

enormousbandwith

orrangeatlower

bandwidth

Terabit/son100pairs(tocellordistribuWonpt)

Terabit/son1pair(fromdistribuWonpttohome)

Transmission-linemode Waveguidemode

TDSL 7 !

7

PhantomsDSL2-pair(4x4)

30R31R

20R10R

32R

21R

3V

2V

1V

0

3I

2I

1I

32~I

321 III ++

21~I

20~I

10~I

31~I

30~I

Ingeneral,Npairà2N-1channels

N=100,andR=5Gbps(G.MGfast)à1Tbps

TDSL 8 !

Issueswith“Phantom”TDSL

•  Onlyback-haulbecauseofreceivermatching– Ormoregenerallyreceivercoordinatedprocessing

•  Mayneedtoomany“repeater”points– EmissionscouldbeproblemaWc

•  Limiteduse-•  BUT,itisaTerabit•  HowaboutaTerabit/lineàWaveguideMode

5/8/17 8

TDSL 9 !

r = 0.5 mm

rcopper = 0.25 mm

plasIcinsulator

copperwire

Aircoresofwaveguide

SinglePair:CableCrossSecWon

•  Today’sxDSLonthecopper(differenWalTEMmode)–  And/ortheairgaps?(green)

TDSL 10 !

SurfaceWaveTransmission(1909Sommerfeldwave)

•  SurfaceMode(orTM10)–  WavesusesinglewireinTMmodeasguide

•  E.g.Goubauantennaor“G-line”•  SeealsoAT&T“AirGig”

–  EffecWvelywirelesstransmission•  Worksreasonablywell(noatmosphereinsidecable)•  Dielectric(plasWc)canhelp(see[Wiltske]),p.971)

keepenergyclose

–  Tubewithnon-uniformdilectricconstant•  Conformalmappingof1/rdimension

•  EnergysWllleaksoffwireifbent Mathfaculty.com

SWEnergy

TDSL 11 !

Surface-WaveMeasurements2006

11

•  SinglewireTM01–  Wiltse’ssurface-wavemeasurementsare2mm

wirecore,not0.5mm)–  Measuresa`enuaWon/m

•  WiltseExtrapolaWon–  .8dB/m@.1-.3THz–  Fa`erwires

•  Grischkowskyhas.5db/m–  For.52mmdiameterCuwire–  2ndwirewouldprobablyimprovetransfer–  Likeintwistedpair

•  100mshouldsee50-80dB

•  Bendingislessofaproblem –  EachwirehasaTMmode–  BetweenwiresisaTEMplasmonpolaritonmode–  2ndTEM“plasmonic”(weaker?)tootherpairs–

somewhatlikephantoms/split-pairs–  TIRmode–  Surfacemode(maybesameasTM…)–  3--4modesperpair

Wiltse

Grischkowsky

TDSL 12 !

3/6differenceisareaofthefree-spaceinatriangular“waveguide”=.16r2

AlWtudeoftriangular“waveguide”=.53r

(600GHzisλ/2)

Ifplas:cused200GHz

r = 0.5 mm

rcopper = 0.25 mm

plasWcinsulator

copperwire

With2L(say100+)wires,therecanbep(2L)transmi`ers(m=0,1,…)orantennasintowaveguidegaps(triangles)ManyreflecWonstoanyspaWalpoint:(waveguideisreally“SwissCheese”withmanyinterconnecWngspaces).BigMIMOopportunity.MIMOmatrixwithGaussianentriesatanypointinspace,whichissameasRayleighfadinginwireless,exceptstaWcsampleEquivalentof“tunable”laserwithvector-coordinatedexcitaWon?(muchlessa`enuaWon–likefiber?)

Aircoresofwaveguide

MIMOProcessor

CrossSecWonGeometry

difference = .32r2

Circle Area=πr2

Outer Hexagon= 63 r

2

TDSL 13 !

Vectoring=MassiveMIMO•  Letstrym=1withTMantenna(s)wirelesslyexciWngeachwireend

–  PhotoconducWveantennasperhaps?–  BothpolarizaWons(TMandTE)foreachwire

•  Orpossiblyforpairsofwires

•  ThereisalsoaTEMplasmonpolaritonmode–  Atleastone,reallytwo–  CouldthinkofthisasdualpolarizaWon,butnotquitereally–  ThereisalsoatleastoneTIRmode(totalinternalreflecWon)withsheath

•  NominallyintersecWonswouldintroducecrosstalkbetweentheTMsandTEMs

–  UseMIMOorMISO(justlikeinmmWwireless5G,exceptmmW/10)–  Willtendtowardlognormal

•  “SwissCheese”Waveguide–  ULTRArichsca`ering(exactlywhatmassiveMIMOneeds)

•  Coupling(splicing)isopentoinnovaWons,butphotoconducWveandothertypesofantennas/lasers/detectorsdoexistinthesefrequencyrangestoday.

TDSL 14 !

Vectoring~ChannelHardening

•  Sayfrom100GHzto300GHz–  Use4096tones,soroughly50MHzwideeach–  Twowiresinapair,andtwopolarizaWons

•  Itsconceivablethateven2.5bits/toneaverage,so1Tbps

CPE1

CPE2

0

OldDSLAMPort1

OldDSLAMPort2

crosstalk

“wireless”

Customer1

Customer2

VectoredDSLAM

TDSL 15 !

Model

15

•  Channel(Grischkowsky)

•  Xtalk(thispaper)–  Lognormal

•  20dBmtotaltransmitpower,flattransmitPSD

•  4096subcarriersfrom100GHzto300GHz,48.8MHzsubcarrierspacing–  Bitloadingfrom1to12bits/Hz–  10%phy-layeroverheadremovedbeforepresenWngresults–  4.5dBcodinggain,1.5dBimplementaWonloss–  Carriersfrom50GHzto150GHzwereusedforthe10Gbpsresults

•  50pairs,vectorprecodedwitheitherzero-forcinglinearprecoderorNon-LinearPrecoder(NLP)usingGeneralizedDecisionFeedbackEqualizaWon(GDFE);idealchannelesWmaWonassumed.

•  -160dBm/HzbackgroundAWGN.

•  WealsoaddinaTM2andTEM2modefor400GHzto500GHz(sameparameters)

Meank=0dBVar=6dB

TDSL 16 !

ResultsinTbps[down+up]/pair

5/8/1716

1Tbpsat100m

•  CananyPONget1Tbpstoeachcustomer?

0

1

2

3

4

5

6

7

8

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

DataRate(Tbp

s)perhom

e

LoopLength(m)

100-300GHzTDSL,perHomedatarates

NLP

Linearprecoded

TDSL 17 !

BitLoading(eachpolarizaWonof1wire)

5/8/17 17

0

1

2

3

4

5

6

7

8

9

100 110 120 129 139 149 159 168 178 188 198 207 217 227 237 246 256 266 276 286 295

BitLoa

ding(b

its/H

z)

Frequency(GHz)

50m

100m

150m

TDSL 18 !

LongerRange,LowerSpeed?

100Gbps>300m

10Gbps>500m(~0.5km)

0

0.5

1

1.5

2

2.5

3

10 30 50 70 90 110130150170190210230250270290310330

DataRate(Tbp

s)perHom

e

LoopLength(m)

60-120GHzTDSL,perHomedatarates

NLP

Linearprecoded

TDSL 19 !

Very-highspeedTDSL

5/8/17 19

•  AddingTE2andTEM2modesfrom400-500GHz

0

2

4

6

8

10

12

14

10 20 30 40 50 60 70 80 90 100 110 120 130 140 150 160 170 180 190 200

DataRate(Tbp

s)perHom

e

LoopLength(m)

100-500GHzTDSL,perHomedatarates

NLP

Linearprecoded

100meters 300meters 500meters

2Tbps 100Gbps 10Gbps

TDSL 20 !

Antennas(analogprocessing)?

5/8/17 20

•  Whatwouldantennaslooklike?–  Annularringsaroundeachwireend–  AlsoatCPEside

–  PossiblymulWpleco-centricringsatCPEside–  CombinaWons–  Catchasmuchdri{ingenergyonCPEreceiveraspossible(dualforupstreamtransmi`er)

•  Whatwouldcouplingtowaveguideslooklike?(photoconducWve,photodetect)–  Itmaybefeasibletohaveondieacouplerinthis200-400GHzfrequencyrange.

•  Couplinglosses?

•  Havenotincluded“nestedMIMO”overthe4(ormore)antennasperhomeinresults–  Thiswillbealargeimprovement(likevector-bondinginmulW-lineDSL,butperhapsbe`er)

•  Currentplotsignorethisimprovement–  However,wewereopWmisWcontheenergylossa{erthesheath-breakonthesurfacewaves–  Thetwoeffectsmayoffset

TDSL 21 !

DigitalSignalProcessing?

5/8/17 21

•  Conversiondevices?–  Mightnotuseall200GHz,butsWll…–  ADC’srunningat120Gsamples/secondexist(Jari`ech)–  UseMulWcarrier(AMTinsteadofDMT)?

•  EachtonecouldhaveitsownADC/DAC(soeasilyavailable,butmanyinparallel)

•  ProcessingCapabiliWes–  VectorEngine,evenatpertoneof50MHz–  .1-.25Giga-opspertone–  Tera-opsforafullsystem

•  CurrentNvidiaTeslaGP100has5Teraflopsin16nmCMOS•  4-7nmonimmediatehorizonandshouldallowcostreducWon

–  WithinemergingcapabiliWes–  Startat100Gbpsinstead(1/10thecost)?

TDSL 22 !

OpportuniWes–Measurements

5/8/17 22

•  Howgoodisthelog-normalmodelforwaveguidemodes’xtalk?– Mightthisxtalkbelarger?

•  Even10%ofthesenumbersis>>“G.mgfast”

•  Arealcablemeasurementorafewwouldhelp–  Thesemodescertainlyexist,butwhatisa`enuaWon?–  Best/reasonableantenna/interfacedesigns?

TDSL 23 !

Whataboutyet-higher-ordermodes?

5/8/17 23

•  Theyexist!•  Higherbandwidths,buta`enuaWon?

–  Unknownfornow–  Likelyneedevenmoreantennas/wire(MIMO)–  10meters(insteadof100m)mightwork

•  NotclearifwavescouldbefocusedlikesurfacewavesbyMIMOprocessingto“hugthewires”astheyseparateandgotoindividualhomes

•  Groundedshieldwouldcontainthemthough–  PDSL?(P=Petabitor1015)

•  TDSLwillprobablybeenoughfornow

TDSL 24 !

Conclusions

•  TDSListechnicallyfeasiblewith100pairsandphantomsusedforbackhaul–  Alsoroughly1Tbps@100m,100Gbpsat300m,10Gbpsat500m

•  ButofcourseonALL100pairsusedtogether•  SWllcouldbeveryusefulfor5GcellmulWtude

•  Terabit/sDSLperhome(orsmallcell)alsoappearsfeasible–  Usingwaveguidemodesandvectoring–SINGLEpair–  Measurementsofa`enuaWonwouldhelprefinerate/range

•  ProbablywithMIMO-channelcharacterizaWonused•  Couldbeexpensivetoprototype

–  Becauseofprocessing/converterspeedsinvolved

•  Isitworthit?(orshouldwespend$4Trilliontoreplaceallthecopperwithfiberinstead,sayinthenext3-5years…..Orcentury?)–  Would5Gsmallcellsbeacceleratedsincethiswouldreduce

deploymentcost?

5/8/17 24

TDSL 25 !

AcknowledgementsandRefs

•  Prof.JoeKahn,StanfordU.•  Dr.RickyHo,Apple•  Dr.S.Galli,Huawei•  Prof.LeonidKazovsky,StanfordU.

•  J.C.Wiltse,“Surface-WavePropagaWononaSingleMetalWireorRodatMillimeter-WaveandTerahertzFrequencies,”MicrowaveSymposiumDigest,2006.IEEEMTT-SInternaWonal,11-16June2006.

•  R.E.Collin,“HertzianDipoleRadiaWngOveraLossyEarthorSea:SomeEarlyandLate20th-CenturyControversies”IEEEAntandPrp.Magazine,Vol46,No.2,April2004.

•  T.I.Jeon,J.Zhang,andD.Grischkowsky,“THzSommerfeldwavepropagaWononasinglemetalwire,”Appl.Phys.Le`ers,Vol86,2005.

5/8/17 25

TDSL 26 !

BackUP

5/8/17 26

TDSL 27 !

Baremetalwirewaveguide

•  Surfaceplasmonpolariton–  EMsurfacewavethattravelsalonganinterfacebetweenmetal(negaWvepermi�vity)and

dielectric(posiWvepermi�vity)basedonsurfaceelectrondensitychangesbelowmetal’splasmafrequency

•  Phasevelocityandgroupvelocityissame(likefreespace)ànodispersioniffrequencyiswaybelowplasmafrequency

–  E-fielddecaysexponenWallyverWcaltothewireà  energyisconfiedneartheconductorsono1/rtypeofpathloss.Onlysmallohmiclossduetoelectron

sca`eringàsmallinmaterialswithhighconducWvityandhighfrequencyà  Lossabout0.1%~0.25%offieldstrengthin1cmà0.86dB/m~2.1dB/m@0.25THz

–  Problems•  TMmodeàHardtogenerateradiallypolarizedEMwave&lowcouplingcoefficient•  Needtobestraightàloseenergyduetobending•  ConnecWngtwometalwiresarenoteasy

5/8/17h`ps://nanohub.org/resources/1852/download/2006.10.05-ece695s-l09.pdf

27

TDSL 28 !

Splicer

5/8/17 28