Post on 16-Mar-2020
Always Surpassing Customers ExpectationsLG-Nortel Proprietary Information
WDM-PON Overview
2009.9.22
Chang-Hee Lee
LG-Nortel and KAIST
Always Surpassing Customers ExpectationsLG-Nortel Proprietary Information
Content
2
> 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
Always Surpassing Customers ExpectationsLG-Nortel Proprietary Information
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
3
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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
5
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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
17
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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
18
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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