Wavelength-Enhanced Passive Optical Networks with Extended Reach Ken Reichmann and Pat Iannone Optical Systems Research AT&T Labs, Middletown NJ Thanks to Han Hyub Lee, Xiang Zhou, and Pete Magill
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
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
• Lower cost per sub than FTTH
• Less BW than FTTH
Fiber to the node
• Lower cost per sub than FTTH
• Less BW than FTTH
(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)
Wavelength-Enhanced Passive Optical Networks with Extended Reach
ONT Blocking Filters Permit λ Upgrades
ONT 1
TDM down1480-1500 nm
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
TDM down1480-1500 nm
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”
TDM down1480-1500 nm
TDMA up1260-1360 nm
TDM down1480-1500 nm
TDM down1480-1500 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
II. Strategic (long term) Use of Extender BoxTDM PONs with Extended Reach / Split
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
II. Strategic (long term) Use of Extender BoxTDM PONs with Extended Reach / Split
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
1510 nm down1290 nm up
1530 nm down1330 nm up
1550 nm down1350 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
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)