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Terabit DSLsNSF Workshop – July 12, 2018

NYU, Brooklyn

John CioffiProfessor Emeritus, Stanford EE

& CEO/COB ASSIA Inc.ASSIA: K. Kerpez, C. Hwang, I. Kanellakopoulos

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xDSL Migration

26 km 4 km 2 km 1 km 500 m 300 m 100 m 30 m

10M

100M

1G

10G

100 G

1T

10T

Speed(bps)

=X - base-T(4 pairs)

4Tbase-T

40Tbase-T

4-bonded100 - 1000improvement

=x - DSW(1 pair)

T

100G

10G

10T

A A2A2+

VVec

FastFast2

MGFast

=X – DSL(1 pair)

10Gbase-T

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▪ Fiber to the home average cost is $3000/home• No viable return on such investment for telcos

• Only deploy fiber in “cherry picked” regions• Still losing money on even that investment

▪ Fiber part way leaves cost ($100k - $1M/mile) shared over all subtended homes • Has better return on investment ($300/home)

▪ Could copper enable 5G wireless?• Outside “backhaul” needs high-speed to many many more small cell sites

Simplified Business Case

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▪ Many and yet more smaller cells• 3.5, 28-30, 60-70 GHz

• 1 Gbps to 10 Gbps wireless access speeds

▪ Front/back-haul support of 5G Massive MIMO (vectoring for wireless)

5G small-cell infrastructure costs

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Every “street lamp” (drop point)10 Gbps? Maybe more

Fiber ?

Or copper ?

• Deutsche Telekom CTO and CEO (MWC 2017)

– “5G fiber infrastructure cost is 300~500 BILLION € for Europe” (~ 100M cells –say 4000 €/ cell)

• Copper could be 10% of this cost (latency is few micro-second range)

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Virtualization “CORD” & Data Center (DC)

Need for BandwidthVirtualization Server Consolidation

Virtualization fuels DC connection demand for Terabits

Match all 10G/100G baseFiber speeds on copper

10-40TBaseTPossible?

RemainsFiber on long haul

Main Copper Ethernet cost advantage = flexibility

$18BAnnual

Connectormarket

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▪ Orders of magnitude speed increase for copper, helps:• wireless (5G)

• virtualization (data-center)

• Fiber = xTTH (residential) budgets

▪ Allows rethinking• Technical

• Financial (infrastructure capex)

Combine 2 known methods

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Digital

Subscriber

Waveguide

Waveguides

Plasmon

Polariton

Vectoring

(massive

MIMO)

Sub mm WaveTransmission

(5G, 6G)

G.Fast/vecWi-Fi, LTE

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The Waveguide Propagation Modes

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r = 0.5 mm

rcopper = 0.25 mm

plastic insulator

copper wire

Air cores of waveguide

MIMOProcessor

Cross Section of a cable of twisted-pair wires

▪ Green areas (and blue) • Waves are guided• Current is not “in copper”• Copper guides the “wireless” waves• Wavelength < 0.5 mm

▪ Twisting causes• “Swiss Cheese” waveguides• Reflections• Many modes of possible propagation

▪ It’s a MIMO wireless challenge• Which is the same as a vectored DSL • Already proven in use

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Surface Wave Transmission (1909 Sommerfeld wave)

• Surface Mode (or TM10)

– Waves use single wire in TM mode as guide

• E.g. Goubau antenna or “G-line”

• See also AT&T “AirGig”

– Effectively wireless transmission

• Works reasonably well (no atmosphere inside cable)

• Dielectric (plastic) can help (see [Wiltse]), p. 971) or hurt

– Energy still leaks off wire if bent

• Two twisted wires (or even split pairs)– Tends to hold energy to the pair (any pair) better

– TEM Plasmon Polariton mode (per wire to surrounding wires)Mathfaculty.com

SWEnergy

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▪ Single wire TM01• Wiltse’s surface-wave measurements are 2mm wire core, not 0.5mm)• Measures attenuation/m

▪ Wiltse Extrapolation• .8 dB/m @ .1-.3 THz• Fatter wires

▪ Grischkowsky has .5 dB/m• For .52mm diameter Cu wire• 2nd wire would probably improve transfer• Like in twisted pair

▪ 100m should see 50-80 dB

▪ Bending is less of a problem• Each wire has a TM mode• Between wires is a TEM plasmon polariton mode• 2nd TEM “plasmonic” (weaker?) to other pairs – somewhat like

phantoms/split-pairs• TIR mode• Surface mode (maybe same as TM …)• 3 -- 4 modes per pair

Waveguide Measurements 2006

Wiltse

Grischkowsky

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▪ Senses THz energy (as well as emits)

▪ Can be constructed (in arrays) in semiconductor• Uses also 3D circuit board (3D printer)

Single sensor/antenna basics

Courtesy, Prof A. Arbabian, Stanford

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Vectoring = Massive MIMO

• Multiple modes for each wire– TM mode (“surface”) – TEM plasmon polariton mode– TIR modes (total internal reflection)

• “Swiss Cheese” Waveguide – ULTRA rich scattering (exactly what massive MIMO needs)

PhotoDetector

PhotoDetector

PhotoDetector

PhotoDetector

PhotoDetector

PhotoDetector

May not be ableto coordinate

on this side(as in DSL vectoring)

H

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The Signal Processing

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▪ 5G or Ethernet (singular value decomp)• xmit = M ; rcvr =F*

MIMO Channel – H

H = FLM*

H =RQ*

H =QR

Order of users will become important

• Downstream DSL (right QR decomp)

– xmit = Q ; small receiver (NLP =R*)

• Upstream DSL (left QR decomp)

– small xmit ; rcvr = Q* (DFE =R)

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H (MIMO Channel) Model

▪ Channel (Grischkowsky)

▪ Xtalk (this paper)• Log normal

▪ 20 dBm total transmit power, flat transmit PSD

▪ 4096 subcarriers from 100 GHz to 300 GHz, 48.8 MHz subcarrier spacing• Bit loading from 1 to 12 bits/Hz• 10% phy-layer overhead removed before presenting results• 4.5 dB coding gain, 1.5 dB implementation loss• Carriers from 50 GHz to 150 GHz were used for the 10 Gbps results• Plasmonic TEM and TM1 modes are used for each wire• Extended to 8192 carriers below 100 meters (so up to 500 GHz)

▪ 50 pairs, vector precoded with either zero-forcing linear precoder or Non-Linear Precoder (NLP) using Generalized Decision Feedback Equalization (GDFE); ideal channel estimation assumed.

▪ -160 dBm/Hz background AWGN.

Mean k=0 dBVar = 6 dB

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a R

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(Tb

ps)

per

Ho

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Loop Length (m)

100-500 GHz TDSL, per Home data rates

NLP

Linear precoded

Results in Tbps [down+up]/pair

7/13/2018

1 Tbps at 100m

▪ Can any PON get 1 Tbps to each customer?

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Waveguides: Longer Range, Lower Speed?

100 Gbps > 300m

10 Gbps > 500m(~0.5km)

0

0.5

1

1.5

2

2.5

3

10 30 50 70 90 110 130 150 170 190 210 230 250 270 290 310 330

Dat

a R

ate

(Tb

ps)

pe

r H

om

e

Loop Length (m)

60-120 GHz TDSL, per Home data rates

NLP

Linearprecoded

Repeated from last year

Note the Nonlinear Precoder(NLP) gains – this is important

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Very-high speed TDSL

• Adding Plasmonic TM2 and TEM2 modes from 100-500 GHz on each wire

100 meters 300 meters 500 meters

2 Tbps 100 Gbps 10 Gbps

2 Tbps @100 m

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(Tb

ps)

per

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Loop Length (m)

100-500 GHz TDSL, per Home data rates

NLP

Linear precoded

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Very long range Waveguide - squeezes low-end of band

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0

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600 610 620 630 640 650 660 670 680 690 700 710 720 730 740 750 760 770 780 790 800

Dat

a R

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(Gb

ps)

per

ho

me

Loop Length (m)

50-150 GHz TDSL, per Home data rates

1 Gbps at roughly 2100 feet (symmetric) or 640m

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RF over Copper

To Network

Copper binder cable @ 300GHz

RF cable @ 28 GHz

Analog transceiver for copper DAS transceiver for 28GHz

StreetCabinet

DAS antenna

Analog modulator for Copper

Power over copper

• RF over copper is similar to RF over fiber– In addition, power can be sent over copper.

• Copper waveguide mode will provide another rich scattering environment. – A cascade of two rich scattering matrices.

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Signal Processing

• Conversion devices– Fortunately fiber designers have developed ADC’s and DACs

• 8-bit 65 GHz ADC today (fiber –used in 100-400 Gbps fiber) uses 750 mW (might need 4 for 250 GHz, and maybe 2 per wire), so 6-10 Watts

– 17 nm semiconductors (less in 7 nm?)

• Power-cost/bit is probably ok and much less than current ethernet

• Processing Capabilities– Vector Engine, even at per tone of 50 MHz

– 5 Giga-ops per tone roughly (on cancellation side in vectoring)

– 20 Tera-ops today (4000 tones) is about 10 Watts/line

• Watts/bit is probably ok and much less than current ethernet

– Start at 100 Gbps instead (1/10 the cost and power)?

• Recall early stage ADSL and VDSL started in similar ranges

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Call for Early Lab Measurements

▪ Single excitation• Measure all output sensors• Photoconductive excitation and photo detectors

• Expensive but accurate

▪ Start with shorter cables• A 1m cable. (To test TM/TEM mode.)• Stepper positioning of transmitter and receiver• Collection of outputs at different frequencies and positions (H)• Use of periodic training sequences• Store on disk• MIMO signal processing can then occur

▪ Progress to longer cables• 100 m• Different configurations

▪ Investigate cost-effective mass-producible couplers

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▪ Terabit/s per pair appears possible• Pre-competitive cooperation necessary for better

• Measures

• Consequent calculations and projections

▪ Early focus may be narrower band• 10 Gbps at 100’s of meters

• 5G wireless small cells “back/front” haul

• Data centers

▪ Needs early funding and personnel

Conclusions

7/13/2018

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Essential to Reliably Fast Connectivity

www.assia-inc.com

Thank YouEnd of Presentation

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Example Architecture

FFT (IFFT)&

AssociatedDSP

LINE

I/O

8Wires

Cat-”T”

100 GHz

200 GHz

300 GHz

400 GHz

500 GHz

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ý

ïï

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CFP4

4xCFP4

ü

ý

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4xCFP4

ü

ý

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CFP4

ü

ý

ïï

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ïï

CAUI-425G each

100GRouter/E switch

400GRouter/E switch

400GRouter/E switch

100GRouter/E switch

ü

ý

ïï

þ

ïï

Datacenter

Each band could be viewed as equivalent to “wavelength” in fiber architectures

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Ethernet Results

• Uses Plasmonic TEM & TEM2, and TM1 and TM2 modes from 100-500 GHz on each of 8 wires

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▪ Profs. Joe Kahn, L. Kazovsky, A. Arbabian, Stanford U.

▪ Dr. Ricky Ho, Apple

▪ Dr. S. Galli, Huawei

▪ Prof. D. Mittleman, Brown U.

▪ Dr. N. Swenson (Collinear)

▪ T. Cil (ASSIA)

▪ J.C. Wiltse, “Surface-Wave Propagation on a Single Metal Wire or Rod at Millimeter-Wave and Terahertz Frequencies,” Microwave Symposium Digest, 2006. IEEE MTT-S International, 11-16 June 2006.

▪ R.E. Collin, “Hertzian Dipole Radiating Over a Lossy Earth or Sea: Some Early and Late 20 th-Century Controversies” IEEE Ant and Prp. Magazine, Vol 46, No. 2, April 2004.

▪ T.I.Jeon, J. Zhang, and D. Grischkowsky, “THz Sommerfeld wave propagation on a single metal wire,” Appl. Phys. Letters, Vol 86, 2005.

Acknowledgements and Refs

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