WDM-PON Overview

22
Always Surpassing Customers Expectations LG-Nortel Proprietary Information WDM-PON Overview 2009.9.22 Chang-Hee Lee LG-Nortel and KAIST

Transcript of WDM-PON Overview

Page 1: WDM-PON Overview

Always Surpassing Customers ExpectationsLG-Nortel Proprietary Information

WDM-PON Overview

2009.9.22

Chang-Hee Lee

LG-Nortel and KAIST

Page 2: WDM-PON Overview

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Content

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> Introduction> Colorless optical sources

• Broadband optical sources• Injection seeded reflective modulators• Tunable lasers

> Architectures• Protection• Broadcasting and Video overlay• OTDR• Upgrade to 10G• Long reach PONs

> WDM-PON global status> Summary

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Introduction: why p-t-p network?

> Trends• Bandwidth growth

• 10 times every 5 years (Nielson’s law, Optical Moore’s law)• Video centric services

• High, bandwidth, high QoS, long connection time• Picture and video clip exchange

• Convergence over fiber based optical networks• Voice, data, video, and wireless (2G , 3G, LTE) • Residential and business

> Observations• Long lifetime of outside plant

• Fiber and passive devices guarantee > 25 years lifetime.• TDM-PON

• Ever changing technology: BPON GPON 10 G PON 40 G PON• Limited scalability due to high speed transmission over high loss link

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WDM PON Values

> Future proof solution• Future proof Lifetime Outside Plant operation (>25years)• Graceful Upgrade Path to Future High Bandwidth Applications

>WDM‐PON scales dedicated BW to 1 G, 10 G and beyond

> Improved Customer Experience• Secure symmetric p‐t‐p connection, No bandwidth sharing• Bit rate and protocol transparencies• Easy protection and fault localization

> Low Total Cost of Ownership• Low OPEX cost effectively provided by colorless ONTs• Low upgrade cost for future high bandwidth services• One infrastructure for residential and business services• Achieved inflection point for component industrialization start• Significant improvements in WDM and DSP to improve reaches aiding in cost reduction

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Colorless optical sources

> Colorless ONT (ONU) is essential for WDM-PON, since multiple users are connected to a PON.

> Methods for colorless operation• Broadband light sources

• A source that covers spectral range of transmission• Suffers slicing losses

• Injection seeding• Injection of seed light from a CO to ONT• ONT has an reflective modulator• Requires seed light

• Tunable lasers• A narrow band light tunable over spectral range of transmission• Needs prior information of wavelength

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Broadband Light Sources

Broadband Light Source

SMF

RNCO

- A simple method

- Slicing loss > 1/N- Limitation in modulation bandwidth for some sources- Beat noises for an incoherent sources

. Beat noise can be mitigated with a low noisemulti-wavelength laser (e.g., QD laser).

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Injection seeded reflective modulators

Reflective modulator

SMF

BLS

CO RN

Seeding sources Limiting factors Reflective modulators

Incoherent light(ASE)

Source noise F-P LD, RSOA, EA+SOANo restriction on spectral response

Coherent light(Bank of DFB LDs)

Reflection noises RSOA, EA+SOARestriction on spectral response

Downstream signal(incoherent or coherent)

Source noise/reflection noise Downstream penalty

Same as above

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Reduction of Reflection Noises

Signal

Upstream signal

PD TIA

AfterReceiver

Reflection noise

Signal

PD TIA

AfterReceiver

Upstream signal

Seed light

November 10, 20098

Seed light

Reflection noise

> Broaden line-width of seed light• Broadband seed light, phase modulation, …

> Shift of signal spectrum

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Tunable laser

Tunable laser

SMF

RNCO

- No slicing loss- Possibly high modulation bandwidth- Low cost tunable lasers are the ultimate end goal.- Coherent detection can improve link budget and channel counts.

. Needs coherent tunable laser and DSP

- Needs prior information for tuning wavelength. End to end control may be complex to mitigate.

- Cost is very high for access applications.

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Architecture of WDM-PON

OLT SwitchOLT

Metro Core

S/WGUI

Cor

eR

oute

r

L2/L

3 sw

itch

Stre

am

Serv

er

ONTTVs

VideoPhonePCs

Phones

TVsVideoPhonePCs

Phones

TVsVideoPhonePCs

PhonesHome

λ1, λ’1

λ2, λ’2TRx1

TRx2

TRxn

TRx3

BLSA

λ3, λ’3

λn, λ’n

WirelessAccess Point

MDU

xDSL

BLSB

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OLT RN

2 x 2N A

WG

BLS(U) BLS(D)

FaultMonitor

Fault Monitor

Fault Monitor

Fault Monitor

Fault Monitor

TRxEthernetSwitch

TRxEthernetSwitch

TRx EthernetSwitch

TRx EthernetSwitch

ONU 1

ONU N

Protection of Fiber Faults

(a) (b)

volta

ge(a

rbitr

ary

units

)

NormalFiber failure

Upstream

8ms

Time (ms)20 8040 60 vo

ltage

(arb

itrar

y un

its)

NormalFiber failure

Upstream

9ms

Time (ms)20 80 10040 60

Normal / DF / FF / Both fault (ONU4)Normal / DF / FF / Both fault (ONU8)

Normal / DF / FF / Both fault (ONU12)

Switching Time

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Broadcast/multicast in WDM-PON

TRx

EM

Multicast/RF overlay

OLT

BLS BLSAW

G•

TRx

TRx

OA splitter

#1#2

#3• • •

WDM 3

1×N

• • •

RN ONUs

12

AW

G

ASE orMW Laser

TRx

TRx

TRx

*EM (External modulator)

*OA (Optical amplifier)

2009-11-10

* Multiple band transmission by using periodic transmission characteristic of AWG

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Broadcast signal transmission at 1.25 Gb/s channel

Isolator

50:50 CouplerF-P LD 1

Isolator

F-P LD 2

Output

-80

-70

-60

-50

-40

-30

-20

-10

0

1555 1557 1559 1561 1563 1565 1567 1569 1571 1573 1575Wavelength (nm)

Pow

er (d

Bm

)

F-P LD@ temp=28.6도123456

78910111213

14151617

18192021

0 0 .5 1 1 .5-150

-140

-130

-120

-110

-100

-90

-80

F re q u e n cy (G H z)

Pow

er (d

Bm

)

100 GHz filtered ASE100 GHz filtered MI F-P LDs

100 GHz filtered ASE

100 GHz filtered MI F-P LDs

> F-P LD 1, 2• Front facet reflectivity of F-P LD : 0.1 ~0.2 %• Laser cavity length : 400 um

> Passive cavity length : 9 cm

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Fault localization with tunable OTDR

ONTCO

λ1

RN

20 km

5 km

CWDM

TRX

AW

G AW

G

L-bandBLS 41

2 3

PIN-PD

F-P LD

Control Unit

Pulse generator

Tunable BPF

Processing Unit

TunableOTDR

TRX

TRX

TRX

TRX

TRX

TRX

TRX

0 5 10 15 20 25 30-90

-85

-80

-75

-70

-65

-60

-55

-50

Distance (km)

Pow

er (d

Bm

)

OTDR Trace

Ch. 10 5 10 15 20 25 30

-90

-85

-80

-75

-70

-65

-60

-55

-50

Distance (km)

Pow

er (d

Bm

)

OTDR Trace

Ch. 2

0 5 10 15 20 25 30-90

-85

-80

-75

-70

-65

-60

-55

-50

Distance (km)

Pow

er (d

Bm

)

OTDR Trace

Ch. 30 5 10 15 20 25 30

-90

-85

-80

-75

-70

-65

-60

-55

-50

Distance (km)

Pow

er (d

Bm

)

OTDR Trace

Ch. 4

BLS(U) BLS(D)

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Upgrade to 10 Gb/s

C/L BLS

M/CPIN

F-P LD

ONT 1

M/CPIN

F-P LD

ONT 32

M/CPIN

F-P LD

ONT K

M/C F-P LD

PIN

32

M/C F-P LD

PIN

1

M/C F-P LD

PIN

K

20 km

. . .. . .

. . .. . .

Upstream

Downstream

OLT RN ONTs

AW

G

AW

GSmooth migration is available to 10 Gb/s in WDM-PON based on the

WL F-P LD by changing the transceivers both at OLT and ONT.

Tunablelaser

Controller

PD

Controller

PD

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Measured wavelength tracking characteristic

1544

1546

1548

1550

1552

1554

1556

1558

1560

1562

0 10 20 30 40 50 60

Wav

elen

gth

[nm

]

Time [minute]

Self wavelength tracking

Wavelength deviation from the target wavelength was 0.05 nm with Gaussian AWG and 0.14 nm with flat top AWG

10 Gb/s W/ BLS

10 Gb/s W/O BLS

2.5 Gb/s W/O BLS

2.5 Gb/s W/ BLS

* ASE injection power = -8 dBm

-30 -29 -28 -27 -26 -25 -24 -23 -22 -21 -20 -19 -18

BLS induced penalty is negligible.

What is BLS : Broadband Light Source?

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LONG Reach WDM-PON

> Passive long reach WDM-PON• Fiber Raman amplifier• Remote pumped EDFA• Reduction of reflection noise is a major issue for injection seeding

method.

> Skipping CO with simple active elements• Seeding sources• Optical amplifiers• Hybrid WDM/TDM-PON

• Increases split ratio up to ~1,000• Solves fiber bottleneck in metro section

• Limited guaranteed bandwidth per user• Requires high bit rate transmission TDM-PON

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Devices for WDM-PON

> Broadband light sources• Amplified spontaneous emission

• Semiconductor based (direct modulation): LED, SLD, …• Doped fiber based (external modulation): EDFA, PDFA, ….

• Multi-wavelength laser (e.g. QD laser)• Low noise• Direct modulation capability is desired.

> Reflective modulators• F-P LD or RSOA• Electro-absorption modulator integrated with SOA

> Tunable laser• Multi-section DFB/DBR laser, VCSEL• PLC type tunable laser

> Athermal AWG• Periodic transmission characteristics

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High density OLT

Source : Infinera

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WDM-PON – Global Status

>WDM‐PONs based on injection seeded BLS were commercialized.

>Global deployment underway• Successful commercial deployment in Korea and Europe• Several Lab, field trials & FOA in US, Canada, Japan, Taiwan 

> 125 Mb/s per channel systems: • 32 channels, 40 km reach capable today

• Residential and Business users• Qualified and deployed in KT network since 2005: 200K users

> 1.25 Gb/s per channel: • 16 channels, 20 km reach available today.• 32 channels system (40 Gb/s) in near future• Fully colorless operation; High immunity on optical back reflection

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WDM-PON vs. TDM-PONMultiple access (upstream) WDMA TDMADownstream WDM TDMGuaranteed BW Line rate Line rate / N (BW sharing)Burst mode No OLT and ONTStatistical gain No YesSplitting loss [dB] 3 – 5 dB (WDM filter loss) 16 - 17 dB (1 x 32 splitter)SNR penalty No N4 ~ N5

Bit rate transparency Unlimited ~ 10 Gb/sProtocol transparency Yes NoOpen architecture and unbundling support Easy Difficult

Fault localization (OTDR) Easy Difficult

Key technologies- Color free optical

source- High speed transmission - Burst mode receiver

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Summary

> Bandwidth Demands are growing (witness this activity)• Engage now to address current and emerging network requirements 

>WDM‐PON is one of the lead candidates for NGA2

>WDM‐PON technology ready for deployment now • Provides future proof OSP and low TCO• Components are available now to build systems• IEEE Standard Ethernet protocol and industry accepted OAM• Complementary to NGA1 and new green field applications