IEEE Communications Magazine • February 2011S12

ADVANCES IN PASSIVE OPTICAL NETWORKS

s an ultimate broadband access solution for futureInternet, the passive optical network (PON) brings

many advantages such as cost effectiveness, energy sav-ings, service transparency, and signal security over otherlast-/first-mile technologies. Over the past several years,we have witnessed significant development and deploy-ment of time-division multiple access (TDMA) PONssuch as IEEE 802.3ah Ethernet PONs (EPONs) and ITU-T G.984 Gigabit PONs (GPONs) to provide high-qualitytriple-play services for residential users. However, futureInternet applications, apart from triple-play service (e.g.,peer-to-peer [P2P] social networking, online video shar-ing, grid computing, and mobile Internet), along withtheir unique traffic characteristics and huge bandwidthrequirements, pose big challenges for current PON designand migration, which in turn are driving legacy TDMAPONs toward ultra-high-speed flexible next-generationPONs such as wavelength-division multiplexed (WDM)PONs and optical orthogonal frequency-division multi-plexed (OFDM) PONs, and/or a hybrid WDM/OFDM/TDM PON.

This special issue features recent and emergingadvances in PONs. Of the large number of submittedpapers, five were selected for this issue . The selected arti-cles cover topics including next-generation PON architec-ture, energy-efficient PONs, layer 2 medium access control(L2 MAC), quality of service (QoS) provisioning in futurePONs, and PON monitoring techniques. The first article,“Opportunities for Next Generation Optical Access,” co-authored by Dirk Breuer, Frank Geilhardt, Ralf Hülser-mann, Mario Kind, Christoph Lange, Thomas Monath,and Erik Weis, discusses the impact of the new businessmodels on network architecture based on the comparisonof different optical access network variants. It also pro-

vides perspective on access node consolidation for networkoperators.

One of the PON’s advantages is the potential to pro-vide high energy efficiency toward future green communi-cations. The second article, “Cost and EnergyConsumption Analysis of Advanced WDM-PONs” con-tributed by Klaus Grobe, Markus Roppelt, Achim Auten-rieth, Jörg-Peter Elbers, and Michael Eiselt, focuses onthe analysis of cost and energy-consumptions of futureadvanced WDM-PON options. The authors conclude thatit is essential to carefully clarify the requirements fornext-generation access with regard to per-PON clientcount and maximum reach. In particular, if client countdoes not exceed ~320, and a passive filter-based opticaldistribution network (ODN) is accepted, the most effi-cient solution, with regard to both cost and power con-sumption, is a simple WDM-PON. The article “TowardEnergy-Efficient 1G-EPON and 10G-EPON with Sleep-Aware MAC Control and Scheduling,” co-authored byJingjing Zhang and Nirwan Ansari, presents L2 tech-niques, proposing sleep-aware MAC control and schedul-ing approaches for EPON. Two sleep-mode control andsleep-aware scheduling schemes are analyzed: sleep forover one DBA cycle and sleep within one DBA cycle.

In addition to reducing energy consumption, multirateand multi-QoS provision is a critical feature next-genera-tion PONs shall possess naturally to cater for existing andemerging Internet applications. The article titled “Multi-rate and Multi-Quality-of-Service Passive Optical NetworkBased on Hybrid WDM/OCDM System” by HamzehBeyranvand and Jawad A. Salehi proposes a new schemeto guarantee multi-QoS in WDM/OCDM system. Thebasic idea is to use multilength variable-weight opticalorthogonal codes (MLVWOOC) as the signature sequenceof an OCDM system. The code weight and code length ofMLVWOOC are designed based on the characteristics ofthe requested classes of services.

The last article, “Passive Optical Network Monitoring:

A

GUEST EDITORIAL

MahmoudDaneshmand

Chonggang Wang Wei Wei

1 Please note that several more papers were accepted as the second part ofthe special issue and will be published in the September 2011 issue ofIEEE Communications Magazine. (Continued on page S14)

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IEEE Communications Magazine • February 2011

Challenges and Requirements,” co-authored by Moham-mad M. Rad, Kerim Fouli, Habib A. Fathallah, Leslie A.Rusch, and Martin Maier, touches on a different problem.In addition to the discussion of challenges and require-ments for PON monitoring, it presents a comprehensivereview of techniques for in-service monitoring PONs todetect and localize faults. The authors recommend thehybrid techniques as promising solutions for delivering themaintenance and protection functionalities required bycurrent and next-generation PONs.

We would like to take this opportunity to thank ourreviewers for their effort in reviewing the manuscripts. Wealso thank the Editor-in-Chief, Dr. Steve Gorshe, for hissupportive guidance during the entire process.

BIOGRAPHIESMAHMOUD DANESHMAND (daneshmand@att.com) is a Distinguished Memberof Technical Staff, AT&T Labs Research; executive director of the UniversityCollaborations Program and assistant chief scientist of AT&T Labs; adjunctprofessor of computer science at the Stevens Institute of Technology; andadjunct professor of electrical engineering at Sharif University of Technolo-gy. He has more than 35 years of teaching, research and publications, andmanagement experience in academia and industry, including Bell Laborato-ries, AT&T Labs, the University of California at Berkeley, the University ofTexas at Austin, Tehran University, Sharif University of Technology, NationalUniversity of Iran, New York University, and Stevens Institute of Technolo-

gy. He has published more than 70 journal/conference papers and bookchapters, co-authored two books, given several keynote talks, and servedas general chair and TPC chair of many IEEE conferences. His current areasof teaching and research include artificial intelligence, knowledge discoveryand data mining, complex network analysis, sensor network and RFID sys-tem reliability and performance, and mining of sensor and RFID data. Hehas Ph.D. and M.A. degrees in statistics from the University of California,Berkeley, and M.S. and B.S. degrees in mathematics from the University ofTehran.

CHONGGANG WANG (cgwang@ieee.org) is a senior staff engineer in InterDigi-tal Communications. Before joining InterDigital Communications, he con-ducted research with NEC Laboratories America, AT&T Labs Research, theUniversity of Arkansas, and Hong Kong University of Science and Technolo-gy. His research interests include future Internet, machine-to-machine(M2M) communications, and wireless networks. He has published morethan 80 journal/conference articles and book chapters. He is on the editori-al boards of IEEE Communications Magazine, IEEE Network, ACM/SpringerWireless Networks, and Wiley Wireless Communications and Mobile Com-puting. He has served as a TPC member for numerous IEEE conferencesincluding ICNP, INFOCOM, GLOBECOM, ICC, and WCNC. He received hisPh.D. in computer science from Beijing University of Posts and Telecommu-nications in 2002.

WEI WEI [SM] (weibit@gmail.com) is a senior engineer at Ciena Corpora-tion. Before joining Ciena, he conducted research with NEC LaboratoriesAmerica and the State University of New York at Buffalo. His research inter-ests include cognitive optical networks, network virtualization, and futureInternet. He has published more than 60 journal/conference articles andbook chapters. He also has rich engineering experiences in developing anddesigning broadband optical networks and IP networks. He is the holder ofthree patents with five others pending. He has served as a TPC member forseveral IEEE conferences including GLOBECOM and ICC. He received hisPh.D. degree in electrical engineering from Shanghai Jiao Tong University.

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GUEST EDITORIAL

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