This document summarizes Joseph Kim's presentation on STMicroelectronics' Advanced System Technology research group and their work on next-generation optical access network architectures. The presentation introduced ST's SUCCESS project, which aims to develop a hybrid WDM/TDM passive optical network with a ring topology that provides backward compatibility and a smooth migration path from current TDM-PON networks. Key aspects of SUCCESS include flexible remote nodes using thin-film tunable filters and splitters, cost-effective ONUs using optical bursts instead of local light sources, and an integrated OLT leveraging tunable laser sources to support both TDM and WDM networks.

1. STMicroelectronics
Advanced System Technology
Next-Generation Optical
Access Architecture
- SNRC Industry Seminar Series -
Joseph Kim
ST Researcher-in-Residence at SNRC
February 24, 2004

2. ADVANCED SYSTEM TECHNOLOGY

3. ADVANCED SYSTEM TECHNOLOGY

4. ADVANCED SYSTEM TECHNOLOGY

5. ADVANCED SYSTEM TECHNOLOGY

6. ADVANCED SYSTEM TECHNOLOGY
Advanced System Technology
Mission
• To provide the advanced system knowledge able
to establish ST as the system on a chip leading
company in the market for the products of the next
decade
Role
• To provide the Company with long-term core
business and leadership in key markets by:
 Identifying fundamental market changes
 Ensuring early access to Intellectual Property
 Developing system architectures and prototypes

7. ADVANCED SYSTEM TECHNOLOGY
SAN JOSE’
SAN DIEGO
CATANIAGRENOBLE
GENEVA
MILANO
AIX EN PROVENCE
BOSTON LECCE
HONG KONG
= large research lab
(>15 people)
NOIDA
BANGALORE
BRISTOL LUGANO
PORTLAND PARIS
AST - Global R&D Organization

8. ADVANCED SYSTEM TECHNOLOGY
AST - Optical Networking Activities
GIANT
Validation of GPON in
demonstrator
Integration of building blocks
Performance (efficiency, QoS)
testing
Service demonstration
GBRA
GXT0
CPA
GLTA Board GNTA Board
GBLA
LD+
AFE
PD+
AFE
WDM
GXTP
NT version
PD+
AFE
LD+
AFE
WDM
CDR
GXTP
LT
version
LD
Driver
ARM
Designed
by STM
Designed
by STM
Designed
by Intec
Designed
by IntecSystem Info control
PTSP OBC PTSP OBC
Designed
by ABell
Designed
by ABell
1.25 Gbps
622 MbpsGBRA
GXT0
CPA
GLTA Board GNTA Board
GBLA
LD+
AFE
PD+
AFE
WDM
GXTP
NT version
PD+
AFE
LD+
AFE
WDM
CDR
GXTP
LT
version
LD
Driver
ARM
Designed
by STM
Designed
by STM
Designed
by Intec
Designed
by IntecSystem Info control
PTSP OBC PTSP OBC
Designed
by ABell
Designed
by ABell
1.25 Gbps
622 Mbps
SYMPHATI
Symmetrical PON at high bit rate
Specify and design chipset for 1.25
Gbps upstream GPON - Class B
Lab demo at 622 Mb/s upstream
APON system

9. ADVANCED SYSTEM TECHNOLOGY
MEMS – free space
Bubble switch
ST Competences in Optics - 1

10. ADVANCED SYSTEM TECHNOLOGY
ST Competences in Optics - 2

11. ADVANCED SYSTEM TECHNOLOGY
Outline
Paradigm Shift in Optical Networking
Next-Generation Optical Access Architecture
• Why Optical Access?
• TDM-PON: Current-Generation Optical Access
• Stanford University aCCESS (SUCCESS)
Summary

12. ADVANCED SYSTEM TECHNOLOGY
Paradigm Shift in Optical Networking
Towards more Flexible, Dynamically-Reconfigurable
Optical Networks from Fixed, Static ones
Driving forces behind this shift
• Mismatch between service/usage model & network infrastructure
• Unbalance between backbone (waste of BW) and access (lack of
it)
• Rapid development in enabling technologies
 Tunable optical components
 Burst-mode communications
 Optical packet/burst/flow switching
Dynamically-reconfigurable networks better meet
varying user demands even with fewer resources!

13. ADVANCED SYSTEM TECHNOLOGY
Traditional Way of Using Wavelengths
TX
TX
TX
TX
RX
RX
RX
RX
SW SW

14. ADVANCED SYSTEM TECHNOLOGY
Optical Network with
Passive/Semi-passive Nodes
New Way of Using Wavelengths
Tunable
TX
SW
Tunable
TX
SW
Tunable
TX
SW
Fixed
RX
SW
Fixed
RX
SW
Fixed
RX
SW

15. ADVANCED SYSTEM TECHNOLOGY
Continuous-Mode vs. Burst-Mode
Communications
TX RXSW SW
...010110100101110100101001001010101111101001010101…
SONET/SDH
Packet Packet Packet
RX SW
10011…0110
Packet Packet Packet
011…010 011…010

16. ADVANCED SYSTEM TECHNOLOGY
Examples
WAN
• TWIN, Lucent Bell Labs
MAN
• HORNET, PNRL/Stanford
• RINGO, Politechnico de Turin
Regional Access
• ONRAMP, Lincoln Lab/MIT
Access
• STARNET, DWA-PON & SUCCESS, PNRL/Stanford
• TOBASCO, Lucent

17. ADVANCED SYSTEM TECHNOLOGY
TWIN: Network is a Giant Switch
TWIN cloud
DS-3
interface
Ethernet
interface
ATM
over OC-3
interface
Traffic destined to this node
should use purple wavelength
Network ~ Logical node
Core ~ Virtual back-plane
Edge node ~ Port * Slide from Indra Widjaja, Bell Labs

18. ADVANCED SYSTEM TECHNOLOGY
Tunable
Transmitter
λ1
POP
Access Point
Access Point
Access Point
Access Point
Access Point
. . . . . .
Wireless
IP Cell
λΝ
Packet
Switch
Local
network
POP = Point of Presence
To long-haul network
λ1
dropMAC
Packet
Receiver
HORNET: Flexible, Multi Service Ring
* Slide from Kapil Shrikhande, PNRL, Stanford

19. ADVANCED SYSTEM TECHNOLOGY
* Slide from Sarah Dubner, MIT Lincoln Lab

20. ADVANCED SYSTEM TECHNOLOGY
OLT
TL1
TL2
TL3
TL4
A
W
G
PON1
Infrastructure
PON4
Infrastructure
ONUs
4 Ultra-fast
Tunable Lasers,
capable of
25GHz tuning
32 λ,
100GHz spacing,
flat top filtersEach Laser can
reach each ONU
λ32
Burst-mode
[all CMOS]Central
Office
Boundary
DWA-PON
* Slide from Matt Rogge, PNRL, Stanford

21. ADVANCED SYSTEM TECHNOLOGY
Enabling Technologies
Common denominator in technologies enabling
flexible, dynamically-reconfigurable optical
networks
• CWDM
• Tunable Filters
• Tunable Lasers
• Burst-Mode Receivers (BMRs)
The paradigm shift pushes these technologies
towards the edge of the networks!

22. ADVANCED SYSTEM TECHNOLOGY
Coarse Wavelength Division Multiplexing
ITU-T Recommendation G.694.2
• 1270-1610 nm, 18 wavelengths, 13nm flat-top
• Permitting low-cost components
 Uncooled, unstabilized, direct-modulated transmitter
Migration path: CWDM to DWDM
• Iannone, “In-Service Upgrade of an Amplified 130-km Metro CWDM
Transmission System Using a Single LOA with 140-nm Bandwidth,” OFC ‘03

23. ADVANCED SYSTEM TECHNOLOGY
Tunable Filters – Promising
Technology for Access
Active thin film (Aegis Semiconductor)
Integrated into semiconductors
Small size & power

24. ADVANCED SYSTEM TECHNOLOGY
Tunable Lasers
Fast tuning time is critical
• State-of-the-art: ~5 ns over entire C-band
 Based on GCSR laser
 Digitally-controlled driver with overdriving pulse technique
* Slide from Kapil Shrikhande, PNRL, Stanford

25. ADVANCED SYSTEM TECHNOLOGY
Burst-Mode Receivers
Focus shifted from OLT to ONUs
One-chip solution preferred
• For mass deployment with ONUs
• Eventually, there will be no cost difference
between continuous-mode & burst-mode receivers

26. ADVANCED SYSTEM TECHNOLOGY
Why Optical Access?
Advantages of fiber as a transmission
medium
• Greater capacity (100s of Tb/s*)
• Smaller size and light weight
• Immune to electromagnetic interference
Fiber penetration in the networks
• Already deployed in the backbone, the WANs, and
the MANs.
• Optical Ethernet is being introduced in LANs and
will spread to MANs and WANs.
* Mitra & Stark, Nature, vol 411, June 28, 2001.

27. ADVANCED SYSTEM TECHNOLOGY
TDM-PON Example - EPON
Proposed 1490nm downstream and
1310 nm upstream (1550 free for WDM
overlays)
Data is transmitted in variable-length
packets of up to 1,518 bytes (i.e.,
Ethernet frame)
Some packets may be intended for all
of the ONUs (broadcast packets) or a
particular group of ONUs (multicast
packets)
Upstream traffic is managed utilizing
TDM technology, in which transmission
time slots are dedicated to the ONUs
Time slots are synchronized so that
upstream packets from the ONUs do
not interfere with each other
The synchronization marker is a one-
byte code that is transmitted every 2
ms to synchronize the ONUs with the
OLT
* Source: Alloptic

28. ADVANCED SYSTEM TECHNOLOGY
TDM-PON Example
- APON (Lucent FTTB/H ONT)
Top View Rear View*
Front View Fiber
Cassette
* UNI cards are PCMCIA type.

29. ADVANCED SYSTEM TECHNOLOGY
Evolution of PONs
TDM-PONs
OLT
ONT
ONT
ONT
WDM-PONs
OLT
ONT
ONT
ONT
?

30. ADVANCED SYSTEM TECHNOLOGY
SUCCESS - Overview
Sponsored by ST/SNRC
• Through F/M/A program
Next-generation optical access architecture based on
• Hybrid WDM/TDM-PONs
• Ring+Tree topology
• Fast Tunable Components
Starting point: How to efficiently/smoothly upgrade
TDM-PONs with those enabling technologies in the
future?

31. ADVANCED SYSTEM TECHNOLOGY
SUCCESS – Major Objectives
Backward compatibility
• To guarantee the coexistence of current-generation (TDM-
PON) and next-generation (WDM-PON) optical access
systems in the same network
Easy upgradeability
• To provide smooth migration paths:
 TDM-PON ⇒ Hybrid WDM/TDM-PON ⇒ WDM-PON
Protection/restoration capability
• To support both residential/business users on the same
access infrastructure

32. ADVANCED SYSTEM TECHNOLOGY
SUCCESS – Features
Flexible Remote Nodes (RNs) with protection & restoration
capability
• Thin film filters as CWDM add/drop filters
• Passive splitter for TDM-PONs
• Athermal cyclic AWG for new WDM-PONs
Cost-effective ONUs for WDM-PON
• No local light source (for DWDM)
 Optical bursts provided by OLT for upstream transmission, are
modulated by SOA at ONU, and send back to OLT.
 New MAC protocols designed for efficient bidirectional transmission
Integrated OLT
• Based on tunable components
• Can support both TDM-PONs and WDM-PONs

33. ADVANCED SYSTEM TECHNOLOGY
:Passive splitter
C :CWDM, splitter
C
C
C
Single Fiber, bi-directional transmission
Network Migration Scenario
CO
“Plain-old” PON
2×N
Flexible, protected, efficient
Access Networks.
Old ONUs and dist.
fibers are preserved.
W
W :DWDM, AWG
Co-Existing TDM/WDM-PONs
W
W

34. ADVANCED SYSTEM TECHNOLOGY
RN with Passive Splitter
2×N
Downstream:
1550.12nm
Upstream:
1310nm
RN
15dB
4~32 ONUs
N×N
RN
ring ringring ring
Other λs
Downstream:
1550.12nm
Upstream:
1310nm
Downstream:
1550.92nm
Upstream:
1290nm
Other λs
ONU group #2 ONU group #1
N-2N-2
For TDM-PONs

35. ADVANCED SYSTEM TECHNOLOGY
For WDM-PONs
Based on Athermal cyclic AWG
BW of the thin-film band splitter (for DWDM λs):
• Up/down-stream shares same λ: (N-1)×Δ.
• Up/down-stream have different λ : (2×N-1)× Δ.
RN with AWG
N-1 ONU N-1 ONU
AWG
.
.
.
.
.
.
λ
ring ring
RN
Other λs

36. ADVANCED SYSTEM TECHNOLOGY
Semi-Passive RN for
Protection/ Restoration
10/90
Elec.
Ctrl.
2×2
switch
N-1 N-1
Band splitters (A/D)
Passive splitter
or AWG
West East
Power from
one ONU
RN

37. ADVANCED SYSTEM TECHNOLOGY
ONUs for WDM-PON
SOA
distribution
fiber
Single port VCSOA
as modulator
SOA
2
3
1distribution
fiber
SOA may be used
as pre-amplifier
No local DWDM source for lowering cost
SOA as modulator and/or pre-amp

38. ADVANCED SYSTEM TECHNOLOGY
to the ring
WDM
coupler
CWDM
DWDM
Fast TLS
Pre-Amp
Post-Amp
Demux
TF
same
ISP
…
OLT Structure
 Use tunable components to reduce transceiver counts and
network cost.
 Each ISP can have TX/RX pair(s) to bundle/unbundle
data in optical domain.
 The number of fast tunable laser sources depends on the
number of users, services, and the network load.

39. ADVANCED SYSTEM TECHNOLOGY
ONU1 ONU2
ONU3
scope
pattern generator
AWG AWG
SMF:2.2km SMF:15km
SMF:5km
SMF:15kmSMF:2.2km
ONU
SOA AM
TLS:λ2
TLS:λ1
OBPF EDFA
thin-film A/D
circulator
passive splitter
OLT
75/25
Experimental Setup

40. ADVANCED SYSTEM TECHNOLOGY
800 ps
800 ps
Experimental Results
Downstream Data Eye Diagram:
Upstream Data Eye Diagram:
2 ms
2 ms
leading edge of
CW burst on λ1
leading edge of
upstream traffic on λ1
2 ms
The timing diagram of packetized
transmission based on SUCCESS MAC:
Downstream
packets and CW
bursts on λ1
Downstream
packets and CW
bursts on λ2
Upstream
traffic monitored
at OLT

41. ADVANCED SYSTEM TECHNOLOGY
SUCCESS WDM-PON MAC Protocol
Design goal
• To provide efficient bidirectional transmission
Challenges
• Variable-length frames
• Time-sharing of the same channel for both up-
and downstream traffic
• No separate control channel/frame structure
• No delay equalization
 Need to reduce the impact of different RTTs.

42. ADVANCED SYSTEM TECHNOLOGY
SUCCESS WDM-PON Frame Formats
Delimiter Preamble
(01…01)
1-Bit
ID(=1)
Ethernet Frame
CW
or
16-Bit
Grant
Overhead (= 24 Bits)
Down-
stream
Up-
stream Delimiter Preamble
(01…01)
Overhead
Ethernet Frame 16-Bit
Report
Ethernet Frame …
Delimiter Preamble
(01…01)
1-Bit
ID(=0)
Overhead

43. ADVANCED SYSTEM TECHNOLOGY
First Step - Sequential Scheduling
RX1
RX2
TX1
TX2
TX3
t0
RTT3
λ1
λ2
λ4
G
λ4λ1
New transmission
scheduled!
t1
l1
RTT1
λ2
λ1
t
Example for 3 TXs, 2 RXs & 4 CHs

44. ADVANCED SYSTEM TECHNOLOGY
Simulation Results - Throughput
Upstream Throughput
Downstream Throughput

45. ADVANCED SYSTEM TECHNOLOGY
Next Step - Batch Scheduling
Improvements over sequential scheduling
• Schedule over HOL frames in VOQs with the earliest
available TX and RX
 Room for optimization & priority queueing to minimize wasted
resources for higher throughput and shorter delay
Implementation Options
• Adaptive Batch Size
 Batch size varying upon queue length, packet dead line and
so on
• Multiple sets of VOQs per ONU
 To provide multiple QoS classes and better fairness between
up- and downstream traffic through priority queueing

46. ADVANCED SYSTEM TECHNOLOGY
Batch Scheduling – Timing Diagram
Arrival
Time
Scheduled
TX Time
(n-1)th batch nth batch (n+1)th batch
Scheduling (n-1)th batch Scheduling nth batch and
any remnant from (n-1)th
batch

47. ADVANCED SYSTEM TECHNOLOGY
Batch Scheduling - OLT Structure
…Downstream
VOQs
…Upstream
VOQs Scheduler*
…Polling
VOQs
TX queue
(1 frame)
Tunable
Laser
TX1
Fiber
...
TX queue
(1 frame)
Tunable
Laser
TXM
Pointer to a frame to
be scheduled next
* Scheduler maintains a list of
scheduled transmissions and
receptions where transmission &
reception times, VOQ #, CH #, RX #
and TX # are stored.
Scheduled frames
To RXs (control signals)

48. ADVANCED SYSTEM TECHNOLOGY
Summary
Mismatch between current service/usage model and
network infrastructure is a driving force behind the
paradigm shift in optical networking
• Towards flexible dynamically-reconfigurable optical networking
• Rapid developments in tunable optical components, CWDM, and
BMRs make such dynamically-reconfigurable optical networking
feasible.
• Advances in architectural study push those enabling technologies
towards the edge of the network.
SUCCESS is a joint research initiative for a next-
generation optical access architecture
• Exploiting the benefit of flexible, dynamically-reconfigurable
optical networking in access
• Guaranteeing smooth transition paths from current TDM-PONs to
future WDM-based optical access