Wavelength-Enhanced Passive Optical Networks with...

Wavelength-Enhanced Passive Optical Networks with Extended Reach

Ken Reichmann and Pat Iannone Optical Systems ResearchAT&T Labs, Middletown NJ

Thanks to Han Hyub Lee, Xiang Zhou, and Pete Magill

I. TDM-PON Overview


Single star, radio dropSingle star, radio dropSingle star, radio dropSingle star, radio drop

PON, radio dropPON, radio dropPON, radio dropPON, radio drop

• Low cost drop• Make the business

Case at lower take rates

BB Access withFixed Wireless Drops

Single star, radio dropSingle star, radio dropSingle star, radio dropSingle star, radio drop

PON, radio dropPON, radio dropPON, radio dropPON, radio drop

• Low cost drop• Make the business

Case at lower take rates

BB Access withFixed Wireless Drops

Active electronics

Passive optics

Fiber

Copper

Radio

Broadband Access Architectures

Single starSingle starSingle starSingle star

• Secure

• Costly

Single star

• Secure

• Costly

Active double starActive double starActive double starActive double star

• More economical than single star for long fiber runs

Active double star

• More economical than single star for long fiber runs

Passive Optical NetworkPassive Optical NetworkPassive Optical NetworkPassive Optical Network

• No actives in field• Reduced

maintenance and operations

(Fiber to the Home)Passive Optical Network

• No actives in field• Reduced

maintenance and operations

(Fiber to the Home)

Fiber to the curbFiber to the curbFiber to the curbFiber to the curb

• Lower cost per sub than FTTH

• Less BW than FTTH

(or Fiber to the Node)Fiber to the curbFiber to the curbFiber to the curbFiber to the curb



Fiber to the node



(or Fiber to the curb)

Hybrid Fiber -CoaxHybrid Fiber -CoaxHybrid Fiber -CoaxHybrid Fiber -Coax

• entrenched BB access

• Triple-play todayHybrid Fiber- Coax

• entrenched BB access

• Triple-play today

Power Splitting Starelectrical

• Users share bandwidth• Systems available today• Cheap optics (e.g. ITU G.983)

Passive Optical Network Types

WDM Star

• Dedicated λ per user• Low loss, high BW• More expensive than power splitting

(e.g. CWDM for business, DWDM w/ Colorless ONTs, etc)

λ

Unamplified WDM Hubbed Ring

Users

Hub

OADM

Users

Hub

OADM• Dedicated λ per user• Low loss, high BW• OADMs in Multiple locations (e.g. Cogent’s CWDM FTTB network)

(PONs: no actives or powering in outside plant)

TDM PON Standards

• 622 Mb/s downstream, 155 Mb/s upstream• 20 km logical reach• layer 2 protocol: ATM

APON, BPON (ITU G.983.1 to G.983.8 ratified from 1998 to 2003)

GPON (ITU G.984.1 to G.984.4 ratified from 2003 to 2004)

• 2.5 Gb/s downstream, 1.25 Gb/s upstream• 60 km logical reach, 20 km differential logical reach, up to 1:128 split• Layer 2 protocol: Ethernet over GEM (generic encapsulation method)• Improved bandwidth efficiency (92% downstream)

EPON (IEEE 802.3ah ratified 2004)• 1.25 Gb/s downstream, 1.25 Gb/s upstream• 20 km logical reach• Layer 2 protocol: Ethernet• Takes advantage of Ethernet cost structure• Lower bandwidth efficiency (72% downstream)

10

100

1000

10000

1996 1998 2000 2002 2004 2006 2008

APONBPON

GPON

EPON

downstreamupstream

Line

Rat

e (M

b/s)

Year

10

100

1000

10000

1996 1998 2000 2002 2004 2006 2008

APONBPON

GPON

EPON

downstreamupstream

Line

Rat

e (M

b/s)

Year

GPON is FTTH Network of Choice in N. America

• Natural migration from BPON: Supports legacy TDM svcs, Ethernet, IP• Video is essential: Delivered over IP (IPTV) or over a separate optical band as

conventional analog subcarriers (Enhancement Band as per BPON, G.983.3)• Reach: Class B+ (28-dB) link budget allows 1:32 split with 20 km reach (1:128 split,

60 km logical reach permitted by standard but not practical today)

TDM down1480-1500 nm

TDMA up1260-1360 nm

20 km

Passive SplitterONT

Up to 32 ONTs

ONTOLT

COPassive Splitter

ONT

ONT

ONTs

ONTOLT

CO

OLT = Optical line terminalONT = Optical network terminal

VideoOLT

Video1550 nm

II. PON Evolution Beyond Current GPON (EPON)


ONT Blocking Filters Permit λ Upgrades

ONT 1


TDMA up1260-1360 nm

1:32 Splitter

PON OLT

Standard GPON

ONT 8ONT 9

CO

The addition of an inexpensive blocking filter to the standardGPON ONT allows unaffected GPON operation as new wavelengths (future services) are added for some users

ONT 32

ONT 25

ONT 24

ONT 17ONT 16

= Blocking filter


TDMA up1260-1360 nm

1:32 Splitter

PON OLT

ONT 8CO

WDM

Gig E

3-D TV

ONT 1

ONT 9

Upgraded GPON (showing two new services)

• 2 λs per symmetrical svc (e.g. Gig E)• 1 λ per asymmetrical svc (e.g. 3-D TV) • Only upgrade ONTs requiring new service

ONT 16ONT 17

ONT 24

ONT 25

ONT 32

ONT Blocking Filters Permit λ Upgrades

= Blocking filter

C+L-band blocking filter will likely be standardized by ITU-T later this year

New λs

• Extend current generation GPON (within 60 km logical limit)

40 km would likely be sufficient given current placement of AT&T COs

• Use extender box only for those GPONs that would otherwise require remote OLTExtender box has cost advantages (capex and opex) over powered remote OLT

• Consider OEO or optical amp-based “extender box”

• One extender box circuit per PON minimizes change to GPON architecture

No additional wavelength or electronic muxing (thus minimizing changes to OSS)

I. Tactical use of a TDM PON “Extender Box”


TDMA up1260-1360 nm



TDMA up1260-1360 nm

TDMA up1260-1360 nm

20 - 60 km

Remote Node(Primary Flexibility Point)

CommonCable

PON OLT

1:32

ONT 1

ONT 32

ONT 2Extender BoxPON OLTPON OLT

1:32

ONT 1

ONT 32

ONT 2Extender BoxExtender Box

TDM PONs with Extended Reach / Split

I. Tactical use of a TDM PON “Extender Box”

TDM PONs with Extended Reach / Split

OEO version: Zenko Technologies (Yusuke Ota)

Optically-amplified version (SOAs): Alphion

1 4 9 0 nm →← 1 3 1 0 nm

2x2tap

coupler

photodiode

1555/(1490,1310)

WDM

1310/1490WDM

controlelectronics

1310/1490WDM

2x2fusedf iber

coupler

2x2tap

coupler

1555/(1490,1310)

WDM

photodiode

photodiode

SOA

SOA

external video opt ical am plif ier (EDFA) (opt ional)

1 4 9 0 nm → 1 4 9 0 nm →

1 4 9 0 nm → 1 4 9 0 nm →

1 4 9 0 nm →1 4 9 0 nm →

1 4 9 0 nm →

← 1 3 1 0 nm ← 1 3 1 0 nm

1 4 9 0 nm →← 1 3 1 0 nm← 1 3 1 0 nm

← 1 3 1 0 nm

← 1 3 1 0 nm

← 1 3 1 0 nm← 1 3 1 0 nm

1 5 5 0 nm →

BPF

BPF

photodiode

Repeater

II. Strategic (long term) Use of Extender BoxTDM PONs with Extended Reach / Split

CentralOffice

Red lines represent subset of individual PONs

BT’s Long-Reach PON Strategy

CO Serving Area

(20 km radius)

New CentralOffice


BT’s Long-Reach PON Strategy

Red lines represent subset of individual PONs

• Long-reach PONs (60 – 100 km max reach)Eliminate majority of COs

Saves on: powering,real estate

Avoids remoting OLT

• Possibly increase users per PON

• WDM or TDM muxing between OLT and Extender Box

Shares feeder fiberReduces fiber management issues

(see Davey and Payne, ECOC’05, paper WE2.1.3)

Bi-Directional Extender Box Based on Hybrid SOA-Raman Amplifiers Downstream

• 1500-nm SOA: 300mA

• 4.5-km Raman Fiber

• Raman pump: 247 mW@ 1456 nm

• 1300-nm SOA: 300mA

• 3.5-km Raman Fiber

• Raman pump: 310 mW@ 1272 nm

Upstream

Upstream


Raman Pumps1272 nm1456 nm

1.5 µm SOA Raman Fiber

4.5 km

3.5 km1.3/1.5 µm MUX

1460 1480 1500 1520 1540 1560-4

0

4

8

12

16

20

24 SRHA : Gain NF PDG SOA Gain RFA Gain

Gai

n / N

F (d

B)

Wavelength (nm)

DownstreamGPONband

Enhancementband

1280 1300 1320 1340 1360-5

0

5

10

15

20

25

30 Hybrid : Gain NF PDG SOA gain RFA gain

Gai

n / N

F (d

B)

Wavelength (nm)

CWDMλ’s (nm)1490151015301550

1290131013301350

60 km

1.3 µm Tx

ONT1.5 µm RxCO OLT Tx

CO OLT Rx

Rx1350 nm

1290 nm

Rx1310 nm

Rx1330 nm

Rx

DFB-LD1550 nm

1490 nm

DFB-LD1510 nm

DFB-LD1530 nm

DFB-LD

C W

D M

C W

D M

C W

D M

C W

D M

2:2

2:2

2:2

2:2

1:16

1:16...

.

.

.

1.3/1.5 μm Mux

60 km

1.3 µm Tx

ONT1.5 µm Rx

1.3 µm Tx

ONT1.5 µm RxCO OLT Tx

CO OLT Rx

Rx1350 nm

1290 nm

Rx1310 nm

Rx1330 nm

Rx

DFB-LD1550 nm

1490 nm

DFB-LD1510 nm

DFB-LD1530 nm

DFB-LD

C W

D M

C W

D M

C W

D M

C W

D M

2:22:2

2:22:2

2:22:2

2:22:2

1:161:16

1:161:16......

.

.

.

1.3/1.5

Experimental Set-Up

1.3-μmHybrid Amp

Remote Node

1.5-μmHybrid Amp

1490 nm down1310 nm up




Note: The erbium-doped fiber amplifier (EDFA) revolutionized optical communications with its capability of simultaneously amplifying a multiplicity of WDM channels. Due to low cost and high performance, it remains the only broadly deployed optical amplifier technology despite the fact that it has a limited optical bandwidth → the hybrid amplifier may fill the niche for broadband (multi CWDM or DWDM) gain at any wavelength.

2.488 Gbps, 231-1 PRBS, Up and Down

1.5 um Amp + 1.3 um Amp + 60 kmUp

-37 -36 -35 -34 -33 -32 -31 -30 -29111098

7

6

5

4

3 1290 nm 1310 nm 1330 nm 1350 nm

Erro

r Pro

babi

lity

(10-y

)

Received Power (dBm)

DownEr

ror P

roba

bilit

y (10

-Y)

1490 nm1510 nm1530 nm1550 nm

-37 -36 -35 -34 -33 -32 -31 -30 -2911109

8

7

6

5

4

3

Received Power (dBm)

Experimental Results

Potential enhancement strategies for TDM-PONsA. Wavelength upgrades permitting increased capacity or additional services

B. Increased link budget for moderate extended reach / split

Hybrid amp suitable for non-erbium band amplification

in access and metro enables A & B simultaneously• Broad bandwidth (>80 nm)

• Reasonable and Bidirectional gain (> 18 dB in latest demonstration)

• Flexible design: flat gain in any band in optical fiber

• Four 60 km PONs sharing a common infrastructure

Summary

Backup Slides

DWDM PON with Colorless ONTs

Source: White paper by Novera Optics, Inc.

• Colorless ONTs• Futureproof outside plant

Impressive technological achievement

• BLS (Broadband Light Source) output power requirements• Cost per user• Polarization dependence

• Susceptibility to discrete and distributed reflections• Channel amplitude variation• Will low-cost DFBs be available by time real demand appears?

But not ready for volume FTTP deployment (despite KT roll-out)

Wavelength-Enhanced Passive Optical Networks with...

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