optical networking and technology innovation
TRANSCRIPT
Bell Labs Technical Journal 18(3), 1–3 (2013) © 2013 Alcatel-Lucent. • DOI: 10.1002/bltj.21624
◆ Optical Networking and Technology InnovationAndreas Leven and Eve L. Varma
are being demanded by network providers to assure
future-proof evolution of their optical transport
networks and to improve effi cient usage of the
infrastructure. Flexible grid technology, which offers
the ability to change channel plans and wavelength
spacings to accommodate guard bands or changes in
modulation format, or to increase channel density, is
one dimension. Another dimension is staying ahead
of ever-increasing client service bit rates (beyond
100G) in next-generation optical transport systems.
In addition to ultra-high capacity and fl exible
systems, intelligent and automated operations
remain fundamental requirements.
Since energy effi ciency of optical technologies
does not improve at the same pace as network
capacity growth, power consumption of transport
networks might approach unsustainable levels in the
near future. Technologies are needed that reduce
power consumption either by increasing utilization
effi ciency or by introducing concepts where power
consumption follows the actual network load.
Bandwidth growth continues to drive system
requirements for scale, size, power, and cost with
interconnects starting to become a limiting factor in
system performance. Shrinking the size of the current
generation modules and lowering power dissipation
has become necessary to increase the number of
modules or cards in a system rack slot, leading to
higher overall system capacity at a lower overall cost.
Low power, medium reach chip-to-chip interfaces
are needed to enable high density and lower power
line-card designs. Transmitter assemblies require cost
and size reduction. Photonic integration becomes
essential to optimize designs.
As the demands on industry data rates have
increased along with demands for higher levels of traffi c
aggregation, the communications and networking
OverviewOptical networking technologies have evolved
signifi cantly over the last few years: 100G coherent
has been commercialized; fl exibility in data rate,
frequency grid and modulation format is a hotly
debated topic; energy effi ciency is becoming even
more important, and tighter integration of the packet
and circuit switched world continues to be of highest
interest. Since the last Bell Labs Technical Journal (BLTJ) issue devoted to optical systems and networking
was published in winter 2010, it seems timely to
address these developments in a new BLTJ issue on
Optical Networking and Technology Innovation.
The sustained worldwide growth of bandwidth
demand has been stimulated by an ever-increasing
array of bandwidth-intensive packet services and
multimedia applications. The availability of these higher
bandwidth service offerings, coupled with applications
requiring higher speeds, has resulted in dramatic
increases in access rates in order to enable faster
consumer access to these services. This increase in
access rates has continued to ripple through metro
networks and has been driving enormous increases
in backbone network bandwidth requirements. This, in
turn, has triggered both evolutionary and revolutionary
technology innovation to keep pace with these
demands, impacting all elements of network infra-
structure from backplane architectures, high speed
chip-to-chip/chip-to-module interfaces, and electro-
optical module design through to photonic technology
extension to ever-higher rates and fl exibility. Developing
equipment that meets the challenges of our dynamic
and evolving communications environment is crucial,
and continues to serve as strong motivation for research
revolution and new product development.
Spectral effi ciency growth in transport networks
is approaching physical limits. Increasing fl exibilities
2 Bell Labs Technical Journal DOI: 10.1002/bltj
industries have need of standardization in support of
these next-generation data rates. However, as always,
there is a delicate balance between facilitating the
technology innovation that is so critical to industry
progress, while enabling the availability of
infrastructure elements that help drive costs out of
customer networks.
Issue ContentCapacity growth is still one of the dominating
drivers for innovation in the optical networking area.
Therefore, we start off this special issue with the
paper “Semi-Empirical Description and Projections
of Internet Traffi c Trends Using a Hyperbolic
Compound Annual Growth Rate,” which analyzes
historical U.S. and global Internet traffi c volumes
previously reported for 1990 to the present to project
future macroscopic traffi c volumes to 2020.
Fundamental advances in optical transport
technologies to meet demands for increased fl exibility,
reach, and performance are addressed in “Current
and Future Flexible Wavelength Routing Cross-
Connects,” “Forward Error Correction in Optical Core
and Optical Access Networks,” and “High Speed
Multi-Level Drivers for Spectrally Effi cient Optical
Transmission Systems.”
Novel optical networking architectures and
concepts for supporting new services requirements,
fl exible and reconfi gurable networks, and improving
network resource utilization are provided in “Optical
Ring Metro Networks With Flexible Grid and Distance-
Adaptive Optical Coherent Transceivers,” “A New
Perspective on Burst-Switched Optical Networks,”
and “Elastic Optical Networks: The Global Evolution
to Software Confi gurable Optical Networks.”
Technology innovation for short reach applications
and in the access network is discussed in “Mode Group
Division Multiplexing Graded-Index Multimode Fibers”
and “Low Cost TWDM by Wavelength-Set Division
Multiplexing.” The focus here is on increasing the
capacity by more effi cient utilization of the fi ber
infrastructure.
Improving energy effi ciency and supporting
energy awareness, both from a hardware and software
perspective, is considered in “Optimized ASIC/FPGA
Design Flow for Energy Effi cient Network Nodes,”
and “Protocol Enhancements for ‘Greening’ Optical
Networks.”
Approaches for overall network optimization and
system design are described in “An Analytical Approach
for Estimating Optimal Multi-Layer Network Cost,
Exploiting the Flexible-Grid Optical Technology” and
“System Design Tool for High Bit Rate Terrestrial
Transmission Systems With Coherent Detection.”
This issue concludes with high-speed next-
generation system electrical ASIC interfaces, also
used for interconnections between devices within or
between circuit packs, and next-generation high
speed interconnects that may be electrical or optical.
These are described in “The Migration of the Optical
Internetworking Forum Common Electrical Interface
Standardization to Optical Intra-System Interconnects
Beyond 25 Gb/s” and “Free-Space Optical Backplane
Prototype for Telecommunication Equipment in the
Petabit/s Range.”
As Guest Editors, it is our honor and pleasure to
present you with this special issue on Optical
Networking and Technology Innovation. We are
grateful to the authors, peer reviewers, Editor-in-
Chief, the BLTJ staff, and the Journal’s Editorial
Board for their contributions, professionalism,
cooperation, and constant support.
(M anuscript approved July 2013)
ANDREAS LEVEN is head of the High-Speed Systems and Processing Department at Alcatel-Lucent Bell Labs in Stuttgart, Germany. He received his Ph.D. (Dr.-Ing.) degree from Karlsruhe University, Germany and spent three years at the Fraunhofer Institute of
Applied Solid State Physics, Freiburg, Germany before joining Bell Labs in Murray Hill, New Jersey 13 years ago. His early research focused on coherent optical systems. From 2008 to 2009, he was on leave with
Panel 1. Abbreviations, Acronyms, and Terms
ASIC—Application-specifi c integrated circuitU.S.—United States
DOI: 10.1002/bltj Bell Labs Technical Journal 3
Alcatel-Lucent’s Optical Networking Division in Nuremberg, Germany, supporting 100G development activities. In 2009 he moved back to Bell Labs in Stuttgart. His current interests include signal processing and coding for high-data rate optical communication systems and SDN for transport networks.
EVE L. VARMA is director of standardization within the Alcatel-Lucent IP Transport Business Unit in Murray Hill, New Jersey. She received an M.A. degree in physics from the City University of New York, and has been with Alcatel-Lucent, originally having joined
AT&T Bell Laboratories, for 33 years. She has been contributing to global standards since 1984, and continues to be actively engaged in supporting the development of specifi cations relevant to transport networking solutions within global standards and industry fora including ITU-T, IETF, and OIF. Previous research experience includes specifi cation of transmission jitter requirements, optical transport and its control and management, and associated enabling technology and methodology evolution. She has co-authored two books, Achieving Global Information Networking, Artech House (1999), and Jitter in Digital Transmission Systems, Artech House (1989), and co-authored two chapters in A Comprehensive Guide to Optical Networking for Professionals, Springer (2006). She is a Bell Labs Fellow, and a member of the Alcatel-Lucent Technical Academy. ◆