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Page 1: Optical networking and technology innovation

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

Page 2: Optical networking and technology innovation

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

Page 3: Optical networking and technology innovation

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. ◆