Ngepon

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Ed Harstead, member Fixed Networks CTODora van Veen, Vincent Houtsma, Pat Iannone and Peter Vetter, Bell LabsNovember 2014

Advanced modulation techniques for NG EPON: duobinary

1. Duobinary modulation tutorial

2. How duobinary could be applied to high speed PONs

3. What are the required device bandwidths and power levels, and how might they be satisfied

4. Duobinary modulation experimental results

5. Mitigating the effects of higher serial speed: chromatic dispersion

Contents

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5. Mitigating the effects of higher serial speed: chromatic dispersion

6. Mitigating the effects of higher serial speed: electronics

7. Summary

8. References

Duobinary modulation: reduces spectrum by half

NRZ {0,1} + {0,1,2}

Duobinary*: delay and add filter

NRZ OOK

NRZ {0,1}

0.6

0.8

1

1.2

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-0.2

0

0.2

0.4

0.6

0.8

1

1.2

3

T

Duobinary*: low pass filter approximation

NRZ {0,1} {0,1,2}

Frequency

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-0.2

0

0.2

0.4

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2-0.2

0

0.2

0.4

0.6

0.8

1

1.2

Time

*These are 3-level “electro” duobinary modulations, not to be confused with optical duobinary

OLTONU

Partitioning duobinary functions in TDM PON

Duobinary {0,1,2}NRZ {0,1} 3-level

decisionNRZ {0,1}

NRZ {0,1} 3-level decision

NRZ {0,1}

Duobinary functions

Transmitter-encoded duobinary

E-O O-E

Required ONU transmitter bandwidth = 40% of NRZ

Duobinary {0,1,2}

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OLT ONU

NRZ {0,1} 3-level decision

NRZ {0,1}

Receiver-encoded duobinary

E-O O-E

Required ONU transmitter bandwidth = 40% of NRZ

Required ONU receiver bandwidth = 40% of NRZ

Can get 25 Gb/s symmetric transmission with 10 Gb/s components in the ONU!

Can get 40 Gb/s symmetric transmission with 25 Gb/s components in the ONU!

Duobinary {0,1,2}

25 and 40 Gb/s TDM PON optical architecture

TxAPD

DB Rx

Logic

up BMR

Dip

lex

er

Logic

upBM Tx

Dip

lex

er

down downSOA

Bit rate Modulation OLT Tx ONU APD DB Rx

25 Gb/s Receiver- 25 Gb/s 7 GHz (10 Gb/s)

Downstream

OLT ONU

Re-use 10G EPON

SOA

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Bit rate Modulation OLT BMR ONU BM Tx

10 Gb/s NRZ 10G EPON BMR 10G EPON DML

25 Gb/s Transmitter-encoded

duobinary

12.5 GHz APD Rx 7 GHz Tx (10 Gb/s)

40 Gb/s 20 GHz p-i-n Rx + SOA 11 GHz EML Tx (<25 Gb/s)

Upstream

25 Gb/s Receiver-encoded

duobinary

25 Gb/s 7 GHz (10 Gb/s)

40 Gb/s 40 Gb/s 11 GHz (<25 Gb/s)

25 Gb/s NRZ upstream might also be possible, for future study

Technology exists

Piggyback on 40GBASE-FR, etc.

Piggyback on 100GBASE-ER4

10 Gb/s components

25 Gb/s down 40 Gb/s down 25 Gb/s up 40 Gb/s up*

10GBASE-PR(X) EPON Rx sensitivity -29.5 dBm (U4) -29 dBm (D4)

Changes to account for high speed transmission

Sustain SNR #1: 2-level � 3-level +3 dB

Sustain SNR #2: wider receiver bandwidth 0 dB 2 dB 2.5 dB 4.5 dB

Penalty: suboptimal duobinary encoding +1.5 dB

Factor in improved LDPC FEC coding gain - 1 dB 0 dB

Projected Rx sensitivity (b-to-b) -26 dBm -24 dBm -22 dBm -20 dBm

Optical path penalty (20 km, incl. 1 dB CD penalty)

+1.5 dB

Estimated TDM PON OLT launch power requirements.

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(20 km, incl. 1 dB CD penalty)

Required minimum launch powers OLT ONU

PR-10 loss budget +20 dB -4.5 dBm -2.5 dBm -0.5 dBm 1.5 dBm

PR-20 loss budget +24 dB -0.5 dBm 1.5 dBm 3.5 dBm 5.5 dBm

PR-30 loss budget +29 dB 4.5 dBm 6.5 dBm 8.5 dBm 10.5 dBm

PR-40 loss budget +33 dB 8.5 dBm 10.5 dBm 12.5 dBm 14.5 dBm

Within capability of commercial DMLs/EMLs

Within capability of commercial SOAs

*we assume p-i-n + SOA sensitivity equivalent to APD a combination of DML and/or TEC might eliminate need for SOA

26 Gb/s experiment using standard 10 Gb/s APDDownstream receiver-encoded duobinary

-50

-40

-30

-20

-10

0

Rel

ativ

e R

espo

nse

[dB

]

20151050Frequency [GHz]

APD+TIA BW=7.4 GHz

= Measured APD+TIA Response = Calculated Delay and Add filter

Transmitted NRZ-OOK eye

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D. van Veen, V. E. Houtsma, P. Winzer, and P. Vetter (Bell Labs), "26-Gbps PON Transmission over 40-km using Duobinary Detectionwith a Low Cost 7-GHz APD-Based Receiver," ECOC OSA Technical Digest

1

2

3

4

5

6

7

8

9

10-L

og10

(Bit

Err

or R

ate)

[-]

-26 -24 -22 -20 -18 -16Received Optical Power [dBm]

Bit Error Rata @ 26 Gb/s

PRBS length=215

-1λ=1314 nm

40 km fiber with booster SOA back-to-back with booster SOA back-to-back measurement

Received duobinary eye (with decision threshold levels indicated)

40 Gb/s experiment using commercial 25 Gb/s APDDownstream receiver-encoded duobinary

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V. Houtsma, D. van Veen, A. Gnauck and P. Iannone (Bell Labs), "APD-Based DuoBinary Direct Detection Receivers for 40 Gbps TDM-PON”, 2014, unpublished

1 dB penalty at 130 ps/nm

High speed transmission: Chromatic Dispersion

Duobinary improves CD tolerance by ~2x vs. NRZ

Estimated usable SSMF spectrum (20 km) without DC

40 Gb/s DB EML

25 Gb/s DB EML

25 Gb/s DB DML

10 Gb/s NRZ EML

10 Gb/s NRZ DML

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O-band

• If the O-band is available,

– no dispersion compensation (DC) is required up to 40 Gb/s (EML).

– Up to 25 Gb/s can use DML

• If the O-band is not available,

– 10 Gb/s: can use DML and no DC

– 25 Gb/s: can use EML and no DC

– Only 40 Gb/s will require DC

• DC fiber is low-loss (<3 dB) and low cost, although bulky

• FBG DCMs are smaller and a potential alternative

• EDC for duobinary (esp. burst mode) requires more study

1260 1310 1360 1410 1460 1510 1560 1610

G.652 spectrum (nm)

ONU Tx Max Tx range Co-existence with

10G/25G DML 20 nm

10G EPON

10G/25G/40G

10G EPON + GPON/1G EPON*

ONU Tx Max Tx range Co-existence with

10G/25G DML 20 nm

10G EPON

10G/25G/40G

10G EPON + GPON/1G EPON*

ONU Tx Max Tx range Co-existence with

10G/25G DML 20 nm

10G EPON

Possible O-band co-existence scenarios

10G EPONupstream

NG EPONdown

NG EPONupstream

GPON/1G EPON*10G EPON

NG EPON

1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

NG EPONdown

stream

10

10G/25G/40G EML

5 nm10G/25G/40G

EML 5 nm

10G/25G DML 20 nm

10G EPON + GPON/1G EPON* (shared OLT BMR and MAC)

*DFB laser typical

EPONdown

stream

GPON/1G EPON*upstream

10G EPONupstream

EPONup

stream

O-band

GPON/1G EPON*upstream

10G EPON NG EPONupstream

NG EPONdown

stream

1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

1260 1270 1280 1290 1300 1310 1320 1330 1340 1350 1360

High speed transmission: reducing impact on ONU silicon and power consumption

• Downstream bit interleaving (BI) allows low cost ONU silicon to operate at user rates.

• Can be a simple static BI or dynamic BI

– Example of simple static BI: 40 Gb/s 4:1 BI, analogous to TWDM wavelength stacking, allows the ONU to operate at 10 Gb/s (after the decimator).

10 Gb/s

10G EPON logic10 Gb/s

EPON BMR10 Gb/s

EPON DML Tx

OLT ONU

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CDR

40 Gb/s NRZ

3-level detect

40 Gb/s DB

10 Gb/s NRZ

10G EPON logic

APD/ TIA

Example of a 40/10 NG EPON using static 4:1 bit interleaving

EML/ Tx

Static 4:1

decimator

10 Gb/s NRZ

40 Gb/s NRZ

40 Gb/s DD duobinary receiver

– Dynamic bit interleaving: where the aggregate TDM PON bandwidth can be 100% flexibly allocated across the ONUs

Static 4:1 BI+

10G EPON logic

10G EPON logic

10G EPON logic

10G EPON logic

ONU components summary

PON flavor

Laser

APDO-band available

O-band not available

25/10 10 Gb/s DML10 Gb/s APD

25/25 10 Gb/s DML 10 Gb/s EML

Can be satisfied by:

25 Gb/s components

10 Gb/s components

40/10 10 Gb/s DML

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• 100GBASE-ER4 25 Gb/s APDs will use the same materials, manufacturing processes, and packaging technologies as today’s low cost 10 Gb/s receivers

• Therefore, the incremental variable cost will be driven by testing at higher speed and lower yield. This premium should become small over time.

components25 Gb/s APD40/25 10 Gb/s DML 10 Gb/s EML

40/40 25 Gb/s EML

TDM PON historical trend

100

1000

10000

100000

Mb

/s

Evolution of TDM PON downstream rate

100

1000

10000

100000

Mb

/s

Evolution of TDM PON downstream rate

40G EPON in 2016?PON type Commercial Deployment Year

Line rate (Mb/s)

Down Up

Narrowband Deutsche Telekom OPAL 1995 29 29

Narrowband NTT Pi PON 1997 49 49

ATM PON NTT 2001 155 155

BPON NTT West 2003 622 155

EPON NTT East 2004 1000 1000

GPON Verizon FiOS 2007 2488 1244

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101990 2000 2010 2020

Commercial deployments

101990 2000 2010 2020

Commercial deployments Trend: 2-year doubling

At each step, TDM PON has overcome 3 main challenges without the aid of WDM

– Higher speed optics and electronics

– More optical power/receiver sensitivity to sustain SNR

– Narrower linewidth lasers to combat chromatic dispersion

Can this be repeated for 25 Gb/s? or 40 Gb/s?

GPON Verizon FiOS 2007 2488 1244

10G EPON China Telecom 2012 10000 1000

Summary

• Duobinary modulation is a tool in a tool box that can be used to achieve higher bit rates from lower speed components

• Although we have performed simulations and experiments, more study is required, especially for the upstream:

– Transmitter-encoded duobinary modulation

– Duobinary modulation and burst mode transmission

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– Duobinary modulation and burst mode transmission

– Burst mode duobinary EDC

FSAN, “Forty gigabit time division multiplexed PON (XLG-PON)”, section 6.2 in “Next-generation 2 access network technology” white paper, 2012 (unpublished)

D. van Veen, D. Suvakovic, H. Chow, V. Houtsma, E. Harstead, P. J. Winzer, and P. Vetter, "Options for TDM PON beyond 10G," in Advanced Photonics Congress, OSA Technical Digest (online) (Optical Society of America, 2012), paper AW2A.1.

D. Suvakovic, H. Chow, D. van Veen, J. Galaro, B. Farah, N. P. Anthapadmanabhan and P. Vetter, “Low Energy Bit-Interleaving Downstream Protocol for Passive Optical Networks”, 2012 IEEE Online Conference on Green Communications (GreenCom), p.26-p31 (2012).

D. van Veen, V. E. Houtsma, P. Winzer and P. Vetter, "26-Gbps PON Transmission over 40-km using Duobinary Detection with a Low Cost 7-GHz APD-Based Receiver," in European Conference and Exhibition on Optical Communication, OSA Technical Digest (online) (Optical Society of America, 2012), paper Tu.3.B.1.

PON duobinary references

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D. van Veen, V. Houtsma, A. Gnauck, P. Iannone, “40-Gb/s TDM-PON over 42 km with 64-way Power Split using a Binary Direct Detection Receiver”, in European Conference and Exhibition on Optical Communication, 2014

Backup

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Delay-and-add filter and low-pass filter approximation

Calculated delay-and-add filter and ideal low-pass filter approximation

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Calculated delay-and-add filter and measured APD/TIA responses

Duobinary demodulator implementation

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Historical: presented to FSAN, Jan. 2012

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(40G DB/10G TDM PON)

(4 x 10G/2.5G)

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