optical ROF

Advanced System Technologies and Field Demonstration for In-Building Optical-Wireless

Network With Integrated Broadband Services Arshad Chowdhury,Member,IEEE,Hung-Chang Chien,Member,IEEE,Yu-Ting Hsueh,Student Member,IEEE,

and Gee-Kung Chang,Fellow,IEEE

Abstract—This work describes a concept of a hierarchical radio-over-?ber(RoF)network architecture that provides both intra-and inter-network connectivity for end user wireline and wireless terminals with high-bandwidth,in-building access ap-plications.An intelligent gateway router(IGR)is proposed as a uni?ed platform to accommodate multi-gigabit,millimeter-wave services at60-GHz band as well as being backward compatible with all current wireless access technologies such as WiFi and WiMAX.In addition,we further present an advanced multi-band optical carrier generation technique that can simultaneously de-liver independent60-GHz mm-wave,2.4-GHz WiFi,and5.8-GHz WiMAX signals ef?ciently carried over the same wavelength,and is suitable for the proposed IGR.Finally,we report,for the?rst time to our knowledge,a campus-wide?eld trial demonstration of RoF system transmitting uncompressed270-Mbps standard de?nition(SD)and1.485-Gbps high de?nition(HD)real-time video contents carried by2.4-GHz radio and60-GHz millimeter wave signals,respectively,between two on-campus research build-ings distanced over2.5-km standard single mode?ber(SMF-28) through the Georgia Institute of Technology’s(GT)?ber network. Index Terms—Broadband wireless access,in-building?ber net-work,optical?ber communications,radio-over-?ber(RoF).

I.I NTRODUCTION

T HE broadband penetration and ongoing growth of In-ternet traf?c among residential and business customers have placed a huge bandwidth demand on the underlying telecommunications infrastructure[1].Today’s Internet traf?c patterns have been propelled from voice-and text-based ser-vices to user-generated interactive video services.Peer-to-peer (P2P)traf?c,which is the largest share of current internet traf?c,contains almost70%traf?c related to the exchange of both static video?les and real-time video communications with dynamic video contents[2].At the same time,irresistible band-width requirements for delivering multi-channel high-de?nition television(HDTV)signals and online gaming services will keep growing toward multi-gigabits/second in the near future. This newer means of communication trends will ultimately test

Manuscript received December01,2008;revised April23,2009.Current ver-sion published June17,2009.

The authors are with the School of Electrical and Computer Engineering, Georgia Institute of Technology,Atlanta,GA30332-0250USA(e-mail: arshad@https://www.wendangku.net/doc/4a7474872.html,;hchien3@https://www.wendangku.net/doc/4a7474872.html,;yhsueh3@https://www.wendangku.net/doc/4a7474872.html,; gkchang@https://www.wendangku.net/doc/4a7474872.html,).

Color versions of one or more of the?gures in this paper are available online at https://www.wendangku.net/doc/4a7474872.html,.

Digital Object Identi?er10.1109/JLT.2009.2022419the network capacity more than pre-recorded video contents. In response to this remarkable development,the metro and core networks of the telecommunication infrastructure have experienced tremendous growth in bandwidth and capacity with the wide deployment of?ber-optic technology in the past decade[3],[4].However,the ultimate bottleneck to the end users terminal is still contributed by the last mile and last meters wireline and wireless access systems with limited bandwidth capacity.In order to avoid being such bottleneck in the last miles and last meters,and to exploit the bene?ts of both wired and wireless technologies,carriers and service providers are actively seeking a converged network architecture to deliver various services to serve both?xed and mobile users.Therefore, optical-wireless access technologies,named as radio-over-?ber (RoF),[5]–[13]have been considered the most practical and ef?cient solution to increase the capacity,coverage,bandwidth, and mobility,and is especially suitable for providing?exible and full connectivity for in-building environments such as conference centers,airports,hotels,shopping malls–and ultimately to homes and small of?ces.

Various RoF systems with WiFi(2.4-GHz)or WiMAX (5.8-GHz)overlay that deliver multi-megabit signal over in-building?ber network have been proposed and demon-strated[10]–[13].On the other hand,RoF system architecture operating at60-GHz millimeter-wave(mm-wave)has recently gained much attention for their huge bandwidth over7-GHz unlicensed millimeter-wave(mm-wave)band with spectral availability to achieve multi-gigabit data rate with ef?cient and low power consumption[14].In order to exploit such bandwidth advantage of60-GHz mm-wave,in this paper, we focus on a uni?ed RoF platform that accommodates ad-vanced mm-wave and former RF services simultaneously for in-building broadband access systems.The proposed system comprises hierarchical network architecture to provide broad-band wireless and wireline connectivity to the in-building end user’s terminals in any enterprise(large corporation,of?ce, banks etc.)or campus-wide networks.The rest of the paper is organized as follows:Section II details the system architecture of the service-integrated in-building broadband optical-wire-less network with both intra and inter-network connectivity. Section III describes a novel technique that simultaneously generates independent multi-band optical signals ef?ciently carried by the same wavelength.Finally,for the?rst time to our knowledge,a campus-wide?eld trial demonstration of

0733-8724/$25.00?2009IEEE

Fig.1.System architecture of the next-generation in-building multi-service radio-over-?ber networks.

transmitting uncompressed270-Mbps SD and1.485-Gbps HD video contents carried by2.4-GHz radio and60-GHz millimeter wave signal over2.5-km standard single mode?ber(SMF-28) over the Georgia Institute of Technology’s(GT)?ber network connecting two on-campus research labs using optical-wireless video link is presented.

II.I N-B UILDING F IBER N ETWORK A RCHITECTURE W ITH M ULTI-S ERVICE B ROADBAND C ONNECTIVITY

Fig.1shows the system architecture of the next-generation in-building radio-over-?ber networks that can simultane-ously provide integrated multi-service wireless and wireline broadband connectivity to the end terminals.The core of the architecture is the Intelligent Gateway Router(IGR).The IGR provides signal processing for various protocol-independent wireless-band conversion(RF,Microwave,millimeter wave), routing functionalities,any necessary media conversions,local buffering and storages,authentication and security functions etc.The in-building?ber backbone is used to connect various end terminals(desktop,laptop,camcorder,fax,printer,PDA, I-phone,mobile etc.)via IGR using wireline connection or wireless connection through base station(BS)located at var-ious distribution points in-side the building.The IGR is also used to provide end-to-end connectivity to end user terminals located at different buildings that connected through optical ?ber access networks such as Enterprise networks(large of?ce, corporation,bank etc.),Campus-wide networks etc.For any signal generated by the in-building end user terminal,the IGR will process it in order to decide whether it will be rerouted within the building or to the outside of the building.Thus,the routing functionality of the IGR includes:

a)Connectivity between end-user’s wireline and wireless

terminals with-in the same building.

b)Connectivity between terminals to/from other locations

within the same enterprise network,campus network or outside service provider networks.

Similarly,for in-building wireless connectivity the signal pro-cessing functionalities of the IGR includes:

a)Multi-band wireless up-and down-conversion Microwave

and millimeter wave(MMW)band for high capacity wire-less users.

b)Wireless up-and down-conversion at various RF band for

backward compatible wireless users.

The optical signal distribution and bandwidth allocation with-in the building can be similar to the passive optical network(PON) system.The optical transmitter and receiver functionality of the IGR is similar to the optical line terminal(OLT)functionality and the BSs and the wireline terminals act like optical network unit(ONU)of the PON system.Thus,the in-building?ber network connectivity for downstream and upstream signals between the end-user terminals can follow the connectivity similar to either time-division-multiplexed(TDM)or wave-length-division-multiplexed(WDM)based passive optical network.The up-conversion of downstream optical wireless signal is performed at the IGR before distributed to the BSs. After receiving,the upstream signal can be down-converted to the baseband rate at the BS before transmitting to the IGR, or,conversely,it can be optically transmitted to the IGR and perform the down-conversion to recover the upstream baseband data.As the in-building network architecture envisioned here is as similar as the today’s TDM-or WDM-PON based access system,the colorless lightwave source of the upstream signals can be provided centrally from the IGR.Again,managing the connectivity between end terminals can be performed through IGR.The IGR can receive the upstream signal from transmitter end-terminal and re-routed to the receiver end-ter-minal as downstream signal after appropriate down-and/or

Fig.2.Experimental setup of the optical-wireless system (PM:phase modulator;FM :frequency multiplier;IM:intensity modulator;EA:electrical ampli?er;IL:optical de-interleaver;Eq:Equalizer;LPF:low-pass ?lter;MMW:

millimeter-wave).

Fig.3.Optical spectra for modulated and ?ltered signals a CO (resolution:0.01nm).(a)Generated sidemodes before and after IL1,(b)before and after IL2,and (c)at the BS after IL3.

up-conversion and the process can be vice-versa to provide the bi-directional connectivity between the end-terminals.In all cases,the IGR plays important role of routing the signal to the appropriate destinations and providing the light path for the upstream and downstream signals.

III.S IMULTANEOUS M ULTI -B AND 2.4-GH Z ,5.8-GH Z AND

60-GH Z G ENERATION ON S INGLE W A VELENGTH As described in the previous section,one of the main tasks of the IGR is to generate multi-band wireless signals before transmitting to the distribution points (BS)within the building.Fig.2illustrates the experimental setup of the optical-wireless transmission system comprising simultaneous generation of multi-band 2.4-GHz,5.8-GHz RF and 60-GHz MMW wave using single laser source.At the intelligent gateway router,a continuous-wave (CW)lightwave is generated by a tunable laser at 1554.336nm and modulated by a phase modulator (PM)driven by a 30-GHz electrical sinusoidal clock signal [15],[16].The 30-GHz clock is generated by using 7.5-GHz clock source and a 1:4frequency multiplier.The output of the PM can be written as a combination of various

sidebands,

,

where is the amplitude of the original optical

carrier,is

the Bessel function of the ?rst

kind,is the modulation depth of the

PM,is the driving voltage

of the RF signals,

and

is the generated sidebands.How many sidebands can be generated depends on the amplitude of the driven RF signal on the PM.Here,we assume that the ?rst-and second-order sidebands are generated through

optimization of the modulation

depth

.The peak of the ?rst sideband is at 30-GHz away from the original optical carrier as shown in Fig.3(a).The removal of the carrier and unwanted high-ordered sidebands is achieved by a 50/100-GHz optical de-interleaver (IL1).The optical spectra of the IL1pass band and the separated signals after the IL1are also shown in Fig.3(a).Another 50/200-GHz optical de-interleaver (IL2)is used to separate the remaining four subcarriers.The optical

Fig.4.Optical spectra of the separated multi-band signals at the base station (resolution:0.01nm).(a)2.4-GHz RF signal.(b)5.8-GHz RF signal.(c)60-GHz MMW

signal.

Fig.5.(a)Receiver sensitivities for 2.5-Gbps signal at different wireless distance.(b)Electrical eye diagrams of 2.5Gbps signal at different wireless distance.(c)Measured optical eye diagrams of 2.5-Gbps signal for B-T-B and 25-km SSMF transmission at wireless distance of 4m.

spectrum of the signal after the 50/100-GHz IL1and transmis-sion windows for four ports of the 50/200IL2are shown in Fig.3(b).The second-order sidebands are considered as two carriers to be modulated with 250-Mb/s and 1-Gbps baseband data for Wi-Fi and WiMAX transmission respectively.The optical millimeter-wave is generated using an optical coupler to combine the two ?rst-order sidebands with the frequency spacing of 60-GHz.The generated optical millimeter-wave signals are then modulated by 2.5-Gbps pseudorandom bit

sequence (PRBS)with a word length

of

.After sent to a power equalizer,whose function is to adjust the power of three signals with optical variable attenuators,the two baseband signals and one 60-GHz millimeter-wave signal are coupled by an optical multiplexer and then ampli?ed by an EDFA to obtain 12-dBm power before transmitting over 25-km standard single-mode ?ber (SSMF)to the base station.At the base station,three different signals are separated by cascading two optical de-interleavers (IL3and IL4)with 25/50-and 50/200-GHz channel spacing,respectively.As shown in Fig.3(c),the 60-GHz millimeter-wave signal passes through the odd port of the 25/50-GHz IL3.Fig.4shows the optical spectra of the three separated multi-band signals at the base station.The 60-GHz mm-wave optical wireless signal is op-tically pre-ampli?ed before optical to electrical conversion is performed by a 60-GHz PIN photodiode followed by an electrical ampli?er (EA)with 5-GHz bandwidth centered at 60-GHz.One pair of rectangular horn antennas with gain of 25-dBi at range of 50-GHz to 75-GHz are utilized to broadcast and receive the 60-GHz signal at certain air distances.Finally,the down-conversion is achieved by a balanced mixer and a 60-GHz electrical LO signal which is generated by 15-GHz clock signal and a 1:4frequency multiplier.The other two signals for Wi-Fi and WiMAX transmission are divided by the optical ?lter formed by even port of the 25/50-GHz IL3with the port2and port3of the 50/200-GHz IL4.However,if the 25/50-GHz IL3is replaced with a 33/66-GHz optical ?lter,their performance will be better because the ?ltering window matches the two baseband signals as shown in Fig.3(c).The two signals are then received by two regular PIN photodiodes,each with bandwidth of up to 10GHz and electrically up-con-verted to 2.4-GHz and 5.8-GHz band,respectively,to emulate the function of Wi-Fi and WiMAX transmitters.The generated signals are broadcasted by a 2.4-GHz panel antenna with a gain of 10-dBi and a 5.8-GHz parabolic dish antenna with a gain of 29-dBi,respectively.At the user terminal,the two signals are received by the corresponding Wi-Fi and WiMAX antennas and down-converted t to the baseband forms through electrical mixers using a 2.4-GHz and a 5.8-GHz electrical LO signal,re-spectively.The receiver sensitivities and electrical eye diagrams for 2.5-Gbps on 60-GHz millimeter-wave carrier at different wireless distance are shown in Fig.5(a).After transmitting over 25-km standard single mode ?ber (SSMF-28),the power

penalties at the given BER

of

for different air distance are less than 1.5dB.The penalties result from the chromatic dispersion for the two sub-carriers with 60-GHz spacing and nonlinear modulation in the modulator.The optical eye dia-

Fig.6.BER curves and electrical eye diagrams for 250-Mb/s and 1-Gbps signals after transmitted over 25-km SSMF and 4-m

indoor.

Fig.7.Field trial demonstration setup of the SD/HD video content delivery using 2.4-GHz and 60-GHz mm-wave radio-over-?ber in the Georgia Tech (GT)campus ?ber network.

grams shown in Fig.5(c)show inter-symbol interference (ISI)caused by chromatic dispersion after transmitting over 25-km SSMF,but it still keeps open and clear.Moreover,Fig.5(a)also shows that the receiver sensitivity degrades with the increase of air transmission distances as the power loss is proportional to the distance.The BER curves and corresponding electrical eye diagrams for 250-Mb/s and 1-Gbps signals at wireless transmission distance of 4-m are shown in Fig.6.After 25-km SSMF transmission,for these two signals,there are almost no power penalties as the chromatic dispersion effects are negligible at these rates.

IV .F IELD D EMONSTRATION OF R O F S YSTEM O VER C AMPUS

W IDE F IBER N ETWORK Fig.7shows the system implementation of the ?rst ?eld demonstration of delivering dual service uncompressed 270-Mbps standard de?nition (SD)and uncompressed 1.485-Gbps high de?nition (HD)video content using 2.4-GHz microwave and 60-GHz mm-wave radio signals,respectively,over Georgia Institute of Technology (GT)Campus ?ber back-bone network from Centergy Research Lab at 10th Street to Aware Home Residential Lab at 5th Street.The transmission distance is 2.5km standard single-mode ?ber (SMF-28).At the transmitter (Centergy building ),all optical up-conversion method is used to perform simultaneous generation of 60-GHz mm-wave and up-conversion of 1.485-Gbps HD signals at wavelength 1554.0nm.The all-optical mm-wave generation at 60-GHz is realized by using an optical phase modulator driven by 30-GHz sinusoidal electrical clock signal and an optical de-interleaver as described in the previous section.The HD signal at 1.485-Gbps is generated from the component output of commercially available Sony Blue-Ray Disc player and an

Fig.8.Transmitter and receiver of the 3-screen,dual-service 2.4-GHz and 60-GHz RoF carrying 270-Mbps SD and 1.485-Gbps HD video content.(a)Transmitter at Centergy lab at 10th Street,(b)60-GHz Wireless setup at residential lab at 5th Street,and (c)3-screen receiver at residential lab.

analog-to-digital converter.For 2.4-GHz radio signal,we used electrical mixing and double-sideband optical modulation to up-convert 270-Mbps real-time SD video content generated from a commercially available Canon Camcorder before op-tically transmitted at wavelength of 1550nm.At the receiver (Aware home),direct detection of optical 60-GHz mm-wave signal is performed by a 60-GHz bandwidth PIN photodiode to realize optical-to-electrical conversion.The converted electrical mm-wave signal is then ampli?ed by an electrical ampli?er (EA)with 5GHz bandwidth centered at 60GHz and

3.55before it is broadcasted through a double-ridge guide rectan-gular horn antenna with a gain of 25dBi,frequency range of 50to 75GHz and 3dB beam width of 7.After the wireless trans-mission,the 60-GHz mm-wave signal is received by the end mobile terminal in order to perform the down-conversion and recover the 1.485-Gbps HD video signal.The down-conversion is performed by a 60-GHz balanced mixer using self-re?ective mixing technique.Similarly,the 2.4-GHz radio signal is re-ceived by a 2.5-GHz PIN receiver at the BS and distributed over the wireless to the receiver antenna.The 270-Mbps SD signal is then recovered by down-conversion process.Fig.8shows the transmitter and receiver modules at two separate locations.The 60-GHz up-conversion technique used in this ?eld-trial is qualitatively evaluated for multi-channel 50-GHz DWDM system over 25km SMF-28in [17].We did not measure any

BER in the ?eld-trial,since we do not have any available electrical clock recovery module that is required to recover the clock at the distantly located receiver.However,the video quality displayed at the remote receiver TV screens located at the residential lab (2.5km away from the transmitter at Centergy building)indicates the very good BER performance of the received signal.

V .C ONCLUSION

We have presented a new concept of a hierarchical radio-over-?ber (RoF)network scenario that provides both intra-and inter-network connectivity for high-bandwidth,in-building access applications.We proposed an intelligent gateway router (IGR)architecture as a uni?ed platform to ac-commodate multi-gigabit millimeter-wave services at 60-GHz band as well as being backward compatible with all current wireless access technologies such as WiFi and WiMAX.We also presented an enabling technology for multi-band optical carrier generation technique that can simultaneously deliver independent 60-GHz mm-wave,2.4-GHz WiFi,and 5.8-GHz WiMAX signals on a single wavelength and experimentally evaluated transmission performances of all three wireless bands over 25km of standard signal mode ?ber (SMF-28).Finally,we reported,for the ?rst time,a campus-wide ?eld trial demon-stration of RoF system transmitting uncompressed 270-Mbps

standard de?nition(SD)and1.485-Gbps high de?nition(HD) real-time video contents carried by2.4-GHz radio and60-GHz millimeter wave signals,respectively,between two on-campus research buildings distanced over2.5-km standard single mode ?ber(SMF-28)through the Georgia Institute of Technology’s (GT)?ber network.

R EFERENCES

[1]Global IP Traf?c Forecast and Methodology Cisco Systems,

2006C2011,2008.

[2]A.M.Odlyzko,“Internet traf?c growth:Sources and implications,”

in Proc.SPIE:Optical Transmission Systems and Equipment WDM

Networking II,2003,vol.5427.

[3]J.McDonough,“Moving standards to100GbE and beyond,”IEEE

Commun.Mag.,vol.45,no.11,pp.6–9,Nov.2007.

[4]G.-K.Chang,A.Chowdhury,J.Yu,Z.Jia,and R.Younce,“Next gener-

ation100Gbit/s ethernet technologies,”presented at the APOC2007,

Wuhan,China,Nov.2007,Invited Paper.

[5]G.-K.Chang,Z.Jia,J.Yu,and A.Chowdhury,“Super broadband

optical wireless access technologies,”presented at the OFC/NFOEC

2008,Optical Soc.Amer.,Washington,DC,2008,on CD-ROM,

OThD1.

[6]Z.Jia,J.Yu,G.Ellinas,and G.-K.Chang,“Key enabling technolo-

gies for optical-wireless networks:Optical millimeter-wave genera-

tion,wavelength reuse and architecture,”J.Lightw.Technol.,vol.25,

no.11,pp.3452–3471,Nov.2007.

[7]T.Kuri,H.Toda,and K.-I.Kitayama,“Novel demultiplexer for

dense wavelength-division-multiplexed millimeter-wave-band

radio-over-?ber systems with optical frequency interleaving tech-

niques,”IEEE Photon.Technol.Lett.,vol.19,no.24,pp.2018–2020,

Dec.15,2007.

[8]M.Bakaul,A.Nirmalathas,C.Lim,D.Novak,and R.Waterhouse,

“Simultaneous multiplexing and demultiplexing of wavelength-inter-

leaved channels in DWDM millimeter-wave?ber-radio networks,”J.

Lightw.Technol.,vol.24,no.9,pp.3341–3352,Sep.2006.

[9]Z.Jia,J.Yu,G.Ellinas,and G.-K.Chang,“Key enabling technolo-

gies for optical–wireless networks:Optical millimeter-wave genera-

tion,wavelength reuse,and architecture,”J.Lightw.Technol.,vol.25,

no.11,pp.3452–3471,Nov.2007.

[10]M.J.Koonen and L.M.Garcia,“Radio-over-MMF techniques—Part

II:Microwave to millimeter-wave systems,”J.Lightw.Technol.,vol.

26,no.15,pp.2396–2408,Aug.1,2008.

[11]M.J.Koonen,A.Ng’oma,G.-J.Rijckenberg,https://www.wendangku.net/doc/4a7474872.html,rrode,P.J.

Urban,H.de Waardt,J.Yang,H.Yang,and H.P.A.van den Boom,

“How deep should?bre go into the access network?,”presented at the

ECOC2007,Berlin,Germany,Sep.16–20,2007,Mo1.1.4.

[12]A.Das,A.Nkansah,N.J.Gomes,I.J.Garcia,J.C.Batchelor,and

D.Wake,“Design of low-cost multimode?ber-fed indoor wireless

networks,”IEEE Trans.Microw.Theory Tech.,vol.54,no.8,pp.

426–3432,Aug.2006.

[13]M.J.Crisp,S.Li, A.Wonfor,R.V.Penty,and I.H.White,

“Demonstration of a radio over?bre distributed antenna network

for combined in-building WLAN and3G coverage,”presented at

the OFC2007,Optical Soc.Amer.,Washington,DC,2007,on

CD-ROM,JThA81.

[14]https://www.wendangku.net/doc/4a7474872.html,skar,S.Pinel,D.Dawn,S.Sarkar,B.Perumana,and P.Sen,“The

next wireless wave is a millimeter wave,”Microw.J.,vol.50,no.8,pp.

22–35,Aug.2007.

[15]G.Qi et al.,“Optical generation and distribution of continuously

tunable millimeter-wave signals using an optical phase modulator,”J.

Lightw.Technol.,vol.23,no.9,pp.2687–2695,Sep.2005.

[16]J.Yu,Z.Jia,L.Xu,L.Chen,T.Wang,and G.-K.Chang,“DWDM

optical millimeter-wave generation for radio-over-?ber using an optical

phase modulator and an optical interleaver,”IEEE Photon.Technol.

Lett.,vol.18,no.13,pp.1418–1420,Jul.2006.

[17]A.Chowdhury,H.-C.Chien,J.Yu,and G.-K.Chang,“Novel50-GHz

spaced DWDM60-GHz mm-wave RoF systems using optical inter-

leaver,”presented at the OFC2009,Opt.Soc.Amer.,Washington DC,

2009,on CD-ROM,

OTuB1.

Arshad Chowdhury(M’07)received the B.S.

degree in computer science and engineering from

Bangladesh University of Engineering and Tech-

nology,Dhaka,Bangladesh,in1995and the M.S.

degree in computer engineering from Wright State

University,Dayton,OH,in1999.In2006,he re-

ceived the Ph.D.degree in electrical and computer

engineering from the Georgia Institute of Tech-

nology,Atlanta,GA.

From1999to2002,he worked as a Research Sci-

entist in the Optical Internetworking Research divi-sion at Telcordia Technologies,Red Bank,NJ,where he was actively involved with DARPA initiated next-generation internet(NGI)optical label switching (OLS)and ATD/MONET.He is currently working as a Research Engineer II and managing the Optical Network Research Laboratory in the School of Elec-trical and Computer Engineering at the Georgia Institute of Technology.His research interests include optical wireless radio-over-?ber convergence,optical packet switched(OPS)networks using optical label switching technology,next generation TDM/WDM access systems,spectral ef?cient modulation formats and ultra-high data rate(100Gbps)optical transmission systems,optical-wire-less interconnections for high-speed computing and server systems.He has been granted15U.S.patents on optical layer survivability,optical multicasting and switching as co-inventor and three other pending patents on radio-over-?ber and PON

systems.

Hung-Chang Chien(M’06)received the Ph.D.

degree in electro-optical engineering from National

Chiao Tung University,Taiwan,in2006.

He is currently working as a Member of Research

Staff in the School of Electrical and Computer En-

gineering,Georgia Institute of Technology,Atlanta,

GA.His research interests include millimeter-wave

radio-over-?ber system,time-division-multiplexed

passive optical network,wavelength-division-mul-

tiplexed passive optical network,and in-building

distributed antenna

system.

Yu-Ting Hsueh received the B.S.degree in electrical

engineering from National Tsing Hua University,

Hsinchu,Taiwan,in2003and the M.E.degree in

electro-optical engineering from National Chiao

Tung University,Hsinchu,Taiwan,in2005.She is

currently working toward the Ph.D.degree at the

School of Electrical and Computer Engineering,

Georgia Institute of Technology,Atlanta.

Her current research interests include radio-over-

?ber systems,optical-wireless access networks,

100-Gb/s high-speed transmission systems,and wavelength-division-multiplexing passive optical

networks.

Gee-Kung Chang(F’05)received the Bachelor

degree in physics from the National Tsinghua Uni-

versity,Taiwan,and the Master and Ph.D.degrees

in physics from the University of California at

Riverside.

He devoted a total of23years of service to Bell

Systems—Bell Labs,Bellcore,and Telcordia Tech-

nologies,where he served in various research and

management positions,including Director and Chief

Scientist of Optical Internet Research,Director of

the Optical Networking Systems and Testbed,and Director of the Optical System Integration and Network Interoperability.Prior to joining Georgia Tech,he served as Vice-President and Chief Technology Strategist of OpNext,Inc.,a spin-out of Hitachi Telecom,where he was in charge of technology planning and product strategy for advanced high-speed optoelectronic components and systems for computing and communication systems.He is currently the Byers Endowed Chair Professor in Optical Net-working in the School of Electrical and Computer Engineering of the Georgia Institute of Technology(Georgia Tech),Atlanta.He is an Eminent Scholar of Georgia Research Alliance.He serves as the leader and Associate Director of

Optoelectronics Integration and Packaging Alliance of NSF funded ERC Mi-crosystem Packaging Research Center at Georgia Tech.He is also an Associate Director of Georgia Tech Broadband Institute.He has been granted40U.S. patents in the area of optoelectronic devices,high-speed integrated circuits, optoelectronics switching components for computing and communication systems,WDM optical networking elements and systems,multi-wavelength optical networks,optical network security,optical label switching routers, and optical interconnects for next-generation servers and computers.He has coauthored over230peer-reviewed journal and conference papers.

Dr.Chang received Bellcore President’s Award in1994for his leadership role in Optical Networking Technology Consortium.He won the R&D100 Award in1996for his contribution to the Network Access Module.He was elected as a Telcordia Fellow in1999for pioneering work in the optical networking project,MONET,and NGI.He became a Fellow of the Photonic Society of Chinese-Americans in2000.He is a Fellow of IEEE Lasers and Electro-Optics Society(LEOS)and a Fellow of the Optical Society of America(OSA)for his contributions to DWDM optical networking and label switching technologies.He has been serving in many IEEE LEOS and OSA conferences and committees.He has served three times as the lead Guest Editor for special issues of the J OURNAL OF L IGHTW A VE T ECHNOLOGY sponsored by IEEE LEOS and the OSA.The?rst issue was published in December2000on Optical Networks,the second one in November2004on Metro and Access Networks,and an upcoming one in2007on Convergence of Optical Wireless Access Networks.