COWA was invited by the NSF to participate in this year's Consumer Electronic Showcase. Penn State sent three representatives and
conducted several live demonstrations of a working video transmission link using light and a new accurate Indoor Positioning System
using visible light communication (VLC) technology. The key objective in participating in the Show was to meet prospective companies
and explain the benefits of becoming a COWA member, leading to new member deployment. See more on COWA's participation
Multi-band, Multi-service, Sensing - Metamaterials
September 17 - 18, 2013 in Washington, D.C.
NSF Award: Broadband Sensors Optical Wireless Local Area Networks - (Pennsylvania State Univ - University Park)
Dr. M. Kavehrad presented an invited Keynote. Click on the KEYNOTES
A book titled The Shark's Paintbrush: Biomimicry and How Nature is Inspiring Innovation includes an interview with Mohsen Kavehrad, the W.L. Weiss Chair Professor of Electrical Engineering.
Author Jay Harman interviewed Kavehrad on a paper he published through a Defense Advanced Research Projects Agency/Air Force Research Laboratory project.
"We had discovered the dolphin chirps look like a wavelet waveforms we used to transmit optical pulses through clouds," Kavehrad said in an email. "The book is meant to encourage people to get inspirations from nature to imagine and invent.
UNIVERSITY PARK, Pa. — The College of Engineering has signed a memorandum of understanding (MoU) with China's Huazhong University of Science and Technology (HUST).
General Co-Chairs: Dr. G. K. Chang, Dr. M. Kavehrad
9-11 July 2012, Seattle, Washington.
The National Science Foundation (NSF) has approved an Industry/University Cooperative Research Center on Optical Wireless Applications in Penn State's Department of Electrical Engineering. The center will be funded by a five-year NSF grant and directed by Dr. Mohsen Kavhrad, W. L. Weiss Chair Professor of Electrical Engineering. The Georgia Institute of Technology also will participate in the cooperative project. The center will aim to generate technology that enables manufacturing of specific devices with larger communications capacity by employing integrated opto-electronics device design with interfaces necessary to facilitate collaborative device, system and network design.
Looking for an item in a large department store or mall can be like searching for a needle in a haystack, but that could change thanks to a hybrid location-identification system that uses radio frequency transmitters and overhead LED lights, suggested by a team of researchers from Penn State and Hallym University in South Korea
2011 New Book
2010 GLOBECOM Plenary Speaker
· Speaker: Dr. Mohsen Kavehrad
· Presentation Title: Let There Be Light and Sustainable Energy-Efficient Wireless Applications
· Bios and Abstracts; Miami-Florida, December 2010.
2010 Broadband Optical Wireless Communications for Sensor Networks
- M. Kavehrad, J. Fadlullah, "Wideband optical propagation measurement system for characterization of indoor optical wireless channels," Proc. SPIE, Vol. 7620, 76200E Conference, DOI:10.1117/12.840266, San Francisco, California, January 2010. (INVITED).
· J. Fadlullah, M. Kavehrad, “Indoor High-Bandwidth Optical Wireless Links for Sensor Networks,” IEEE Journal of Lightwave Technology, Vol. 28, No. 21, pp. 3086-3094, November 1, 2010.
In the News:
2009 ETRI Journal Paper of the Year Award
- Ali Enteshari, Jarir M. Fadlullah, and Mohsen Kavehrad, "High-Speed Access over Copper: Rate Optimization and Signal Construction," ETRI Journal, Vol.31, No.5, pp.489-499, Oct. 2009.
This paper was selected as the Paper of the Year and received an award.
2009 Bloom PhD Student Award
· Electrical Engineering Melvin P. Bloom Memorial Outstanding Doctoral Research Award Winner; Ali Enteshari
2009 Greater than 10 Gbps Workshop
- Greater than 10Gbps Copper Ethernet Workshop
- Hosted at Penn State, the workshop is attended by industry leaders
2009 Paper Award
- A. Enteshari and M. Kavehrad, “40/100 Gbps Transmission over Copper: Myths and Realities,” Proceedings of DesignCon, Santa Clara, CA, February 2009.
The above paper received a DesignCon Paper Award in the High-Speed and RF Design Category. DesignCon Paper Awards recognize outstanding contributions to the educational goals of the DesignCon program. Papers are judged both on the merits of the written document and on the quality of their presentation at DesignCon 2009.
2008-2007 Beyond 10 Gbps Transmission on Copper Ethernet
Penn-State Research News: Researchers Push Transmission Rate of Copper Cable
Atlanta, You may not be able to get blood out of a turnip, but according to Penn State engineers, you can increase the data transmission of Category-7 copper cables used to connect computers to each other and the Internet.
Presentation Title: Towards 100G over 100 Meters of CAT-7
Dr. Mohsen Kavehrad, A. Enteshari, J. Fadlullah
News Media :
· Science Daily: Researchers Push Transmission Rate Of Copper Cables
· Network World: Researchers pushing 100 Gig
· United Press International: Copper cable transmission rate increased
· Eurek: Researchers push
· Phys. Org. : Researchers push ....
· StateCollege.Com : Researchers push transmission rate of copper cables
· 4Engr.Com: Researchers say data ...
· ZD-Net : 100 gigabits per second over copper?
· Innovation Reports : Researchers push transmission rate of copper cables
· Mehr News : High-Speed Transmission
· IRIB-News : 100GBASE-T Copper
· Hamshahry: Interview on High-speed over copper
· CeBIT - Newsanzeige :100 GBit/s durch Kupfer gequetscht
· Heise Online : 100 GBit-s durch Kupfer gequetscht
2007-2006 White Light Emitting Diodes for Home Networking
Encoded light transmissions can provide the wireless devices in a room with multimedia Web services such as; video-conferencing, movies on demand and more ….
By: Mohsen Kavehrad
Scientific American Journal, July 2007
· M. Kavehrad, P. Amirshahi, “Hybrid MV-LV Power Lines and White Light Emitting Diodes for Triple-Play Broadband Access Communications,” IEC comprehensive report on; Achieving the Triple Play: Technologies and Business Models for Success, ISBN: 978-1-931695-37-4, December 2005. (.PDF)
· P. Amirshahi and M. Kavehrad, “Transmission Channel Model and Capacity of Overhead Multi-conductor Medium-Voltage Power-lines for Broadband Communications,” IEEE Consumer Communications & Networking Conference,
, January 2005. (.PDF) Las Vegas, Nevada
· P. Amirshahi and M. Kavehrad, “Medium Voltage Overhead Power-line Broadband Communications; Transmission Capacity and Electromagnetic Interference,” Proceedings of ISPLC 2005,
, April 2005. Vancouver, Canada
Penn-State Research News: Optical Wireless And Broadband Over Power Lines
Physic-Org.: Optical wireless and broadband over power lines………….
· Technology News Daily: Optical Wireless………..
· Science Daily: Optical Wireless And Broadband Over Power………
· CNN_Magazine _Com: Wi-Fi alternative
· Industry News - The IEE: LED lighting could deliver wireless broadband, researchers claim
· The SPIE OE magazine: White LEDs offer wi-fi alternative
· LASER Focus-Japan: With white LED high-speed optical wireless communication
Inquirer: Lighting up wireless Internet link Philadelphia
2005 Broadband Transmission over Medium Voltage Powerlines
· P. Amirshahi and M. Kavehrad, ‘Models for Outdoor Channels,” Invited Section in Power Line communications,
John Wiley & Sons Ltd, ISBN 978-0-470-74030-9, 2010.
· P. Amirshahi and M. Kavehrad, “High-Frequency Characteristics of Overhead Multi-conductor Power Lines for Broadband Communications,”
IEEE Journal on Selected Areas in Communications, Vol. 24, No. 7, July 2006.
· P. Amirshahi and M. Kavehrad, “Medium Voltage Overhead Power-line Broadband Communications; Transmission
Capacity and Electromagnetic Interference,” Proceedings of ISPLC 2005,
, April 2005. Vancouver, Canada
· P. Amirshahi and M. Kavehrad, “Transmission Channel Model and Capacity of Overhead Multi-conductor Medium-Voltage
Power-lines for Broadband Communications,” IEEE Consumer Communications & Networking Conference, Las Vegas, January 2005.
· Penn-State Research News: Power Line Data Transmission Capacity: Bigger Than DSL Or Cable
University Park, Pa. -- Penn State engineers have developed a new model for high-speed broadband transmissions over U.S. overhead electric Power-lines and estimate that, at full data rate handling capacity, the lines can provide bit rates that far exceed DSL or cable over similar spans.
... Inside Out, a TV interview: High-voltage electrical power lines could be used for communications, like broadband Internet WPSX-TV Pennsylvania
· Scientific American: Broadband to the people
· The Energy Daily: Repeaters are key –Properly “tuned” power line offers broadest broadband
· BPL Today: Penn-State finds gigabit in US grid
· FCC Chairman Powell kicks off his new regular AO blog: Michael Powell Joins the Blogosphere
· Transmission & Distribution: Researchers…………..
· Betterhumans: Power Line Internet Could Crush Cable, DSL
Innovation report -
· CNN_Magazine: Internet Over Power Lines
ABS CBN News,
· Reuters – France: Des chercheurs prévoient du très haut débit sur ligne électrique
· Science Daily: Power Line Data Transmission Capacity: Bigger Than DSL Or Cable
· Daily Science News: Power Line……….
· The Digital Collegian: BPL offers faster Web connection
· Black Issues in Higher Education: Penn State Engineers Present Expanded View of Broadband by Power Lines
2004 Fractal Wavelet Transmission Free Space Optical Links Through Clouds - Adaptive Rate
Multi-rate, ultra-short laser pulses -- with wave forms shaped like dolphin chirps -- offer a new approach to help optical wireless signals penetrate clouds, fog and other adverse weather conditions, say
engineers. Penn State
Kavehrad, B. Hamzeh, “Beaming Bandwidth via Laser Communications,”
· M. Kavehrad, B. Hamzeh ”Laser Communication System Using Wavelet-Based Multi-Rate Signaling,” Proceedings of IEEE MILCOM, Monterey-California, November 2004.
M. Kavehrad, B. Hamzeh ”Ultra-short Pulsed FSO Communications System with
Wavelet Fractal Modulation,” Proceedings of Optics East,
· Penn-State Research News: Multi-Rate Laser Pulses Could Boost Outdoor Optical Wireless Performance
· Penn-State Board of Trustees meets; President Spanier's Remarks
· Government Technology: Optical Wireless Signals
· SCI-TECH TODAY: Digital Dolphins May Improve Telecom
· GehirnwäschefürMobiltelefone: Per Laserpuls
· Laser Focus World: Multi-rate laser pulses could boost outdoor optical wireless performance
· Laser Focus World: CONF. REVIEW: Optics East features nanotechnology and ITCom
· Sci-Tech-Japan: Digital dolphins
· Wireless News Factor: Digital Dolphins May Improve Telecom
· TelecomDirect News: Laser Pulses Boost Outdoor Optical Wireless Links
and Articles On Elect.
· Korean RF Center: KISTI 2004.11.02
· Handelsblatt.com: Tech.: Forschung + Innovation: Laserpulse senden Daten durch Wolken
· Photonics Online: Multi-Rate Laser Pulses Could Boost Outdoor Optical Wireless Performance
· Photonic Net: Laser-Datenübertragung: Als Puls besser durch Wolken und Nebel
The Engineer: Dolphin chirps send a clear message
2003 10Gbps Transmission over Standard Category-5e or 6 Copper Cable (10GBASE-T)
Research focus here is on conceptual designs and demonstration of a 10GBASE-T copper transmission system for distribution of a digital signal over ~100 meters of a standard CAT-5e or 6 copper cables.
Presentation to the IEEE 802.3
Standards Committee, the 10GBASE-T Study
M. Kavehrad, J. F. Doherty, J. H. Jeong,
A. Roy and G. Malhotra, “10 Gbps Transmission over
Standard Category-5 Copper Cable,” Proceedings of GLOBECOM’03,
· Penn-State Research News: Copper wire shown to be competitive with fiber optic cable for LANS
· Eurek-Alert: Copper wire ……………..
· HimTimes: Copper Wire……………
· Continuity Central: Copper wire broadband LANS shown to have advantages over fibre …
· Today's focus: Cat-6 may go farther…………..
· Wire and Cable International Overview (page-3): Copper seen as competition for FO cable
· Monitor: Copper wire competitive………….
· The WAI Connection: Can copper wire match……….
· Industrial Networking: Copper competitive with fibre optic cable for LANs?
· Business Week: Developments to watch
Innovations-report : Copper wire shown to be competitive with fiber optic cable for LANS
· Digital Education Navigator: Copper Wire Transmission Scheme
· Distance Educator: Copper wire shown to be competitive with fiber optic cable for LANS
· RedNova: Copper Wire Competes With Fiber Optic Cable
· Nexans White Paper: Dynamic Performance……….
· Nexans White Paper: Nexans efforts on 10Gbe over UTP
2002 Dynamic Time-Division Duplex in Broadband Access for Wireless Internet
Dynamic Allocation Technique Boosts Efficiency and Minimizes Interference for Wireless Broadband Systems for Internet Access.
· W.C. Jeong, M. Kavehrad, “Co-Channel Interference Reduction in Dynamic-TDD Fixed Wireless Applications, using Time Slot Allocation Algorithms,” IEEE
· Trans. on Commun., Vol. 50, No. 10, October 2002.
· Penn-State Research News: New Allocation Technique Boosts Efficiency for Wireless Internet Access
2001 IEEE VTS Neal Shepherd Best Propagation Paper Award
Awarded to the paper entitled, "Indoor Wireless Infrared Channel Characterization by Measurements," IEEE Trans. on Vehicular Tech., Vol.-50, No. 4, July 2001, authored by M.R. Pakravan, M. Kavehrad, H. Hashemi. M.R. Pakravan received his Ph.D. degree under Dr. Kavehrad’s supervision in the year 2000 with a Dissertation Title: "Indoor Infrared Wireless Communication Channel”.
2001 Novel Holographic Spherical Mirror as a Receiver Optical Front-end for Broadband Infrared Indoor Wireless Communications,
Novel optical design helps to achieve very high bit rates in wireless infrared in-house communications.
· S. Jivkova, M. Kavehrad, “Holographic Optical Receiver Front-End for Wireless Infrared Indoor Communications,” OSA Applied Optics Journal, June 2001.
§ Penn-State Research News: Low Power, Highly Reliable, Wireless, Infrared LAN
§ New York Times Article: Beaming Data Holds Promise, With Limits, for Networking
§ Center Daily Times Article: Professor sees the future in infrared
§ The Digital Collegian: Researchers look into ways to network computers through infrared light
§ Electronics Times: Inside job for network system
§ IEEE Communications Society Industry NewsCache (INC): Scientists are working on high-speed
§ Science Daily Magazine: Low Power, Highly Reliable, Wireless, Infrared
§ ICON News: Beaming data could be networking's saviour
Wireless News Factor: Does Infrared Have a Chance?
§ Uni-Science: Indoor Wireless LANs Minus Line-of-Sight IR can work
§ Penn-State Intercom: Wireless IR LAN
§ Photonics Spectra: IR Wireless signals High Bandwidth at Low Power
§ TRN News: Holograms control data beams
§ INFORMATICA 2.0: Redes conectadas con rayos infrarrojos….
§ EE TIMES,
§ Laser Focus World: Free-space optical communications
§ December 1998 IEEE Comm. Magazine: Imaging Diversity Receivers for High-Speed Infrared Wireless Communication
1999 Lucent ( Bell Labs.) visit,
Work on Dynamic Time-Division-Duplex Wireless Local Loop, using smart antennas.
· J. Li,
S. Farahvash, M. Kavehrad, R. Valenzuela "Dynamic TDD and Fixed Cellular Networks," IEEE Communications Letters, Vol. 4, No. 7, July 2000.
1999 Broadband Wireless Access Systems
Solutions to the broadband wireless subscriber access problems, e.g., those associated with wireless networks evolution. To name a few; Linearized Transmitters, Propagation Modeling, Network Architecture, Dynamic Time-Division-Duplex Wireless Local Loop, QoS Provisioning for Wireless ATM by Variable-Rate Coding.
The Linearized Transmitters work has been adopted into Agilent Technologies “Linearization Design Guide,” December 2003.
Lockheed Martin Corp. announced a commitment to a variety of student aid needs and research projects in
's Penn State and ... Collegeof Engineering
(From left to right)
Marcus C. Hansen, President of Lockheed Martin Management & Data Systems
Kathleen J. Muhonen, Ph.D. candidate in the Department of Electrical Engineering, CICTR
Dr. Graham Spanier, President of The Pennsylvania State University
Dr. David Wormley, Dean, College of Engineering
Editorial reviews on book description :
Mobile Computing Environments for Multimedia systems brings together in one place important contributions and up-to-date research results in this fast moving area. Mobile Computing Environments for Multimedia Systems serves as an excellent reference, providing insight into some of the most challenging research issues in the field.
· By: B. Prabhakaran (Editor), Mohsen Kavehrad (Editor)
Hardcover - (May 1999) - Kluwer Academic Publishers; ISBN: 0792385497.
1998 Bi-directional Optical Amplifier, U.S. Patent 5,815,308
Allows bi-directional WDM transmission using an Erbium-Doped Fiber Amplifier.
· C. Barnard, J. Chrostowski, M. Kavehrad, "Bi-Directional Fiber Amplifiers," IEEE Photonics Tech. Letters, Vol. 4, No. 8, August 1992.
1996 NORTEL sabbatical visit,
Work on ADSL and VDSL for telephone Network Local Loop.
§ M. Hawryluck, A. Yongacoglu, M. Kavehrad, "Simulation of a FFT-Based Discrete Multi-tone System for ADSL and VDSL Transmission," Proceedings of ISCC'98,
, June 1998. Athens
§ M. Hawryluck, A. Yongacoglu, M. Kavehrad, "Efficient Equalization of Discrete Wavelet Multi-Tone over Twisted Pair," Proceedings of Int. Zurich Seminar on Broadband Communications, Zurich-Switzerland, pp. 193-200, February 1998.
§ M. Hawryluck, M. Kavehrad, "Equalization Requirements for CAP/QAM Transmission at ADSL and VDSL Data Rates on Category-3 UTP: Theory and Simulation Results," Proceedings of CCBR, Ottawa-Canada, April 1997.
1995 WDM / Space Division Multiplexing Optical Cross-Connect
New all-optical cross-connect system with wavelength re-use, allowing construction of large-scale cross-connects. Design was in collaboration with NORTEL,
· Y.D. Jin, M. Kavehrad, "Optical Cross-Connect Based on WDM and Space-Division Multiplexing," IEEE Photonics Tech. Lett., Vol. 7, No. 11, pp. 1300-1302, November 1995.
PhD Thesis Gold Medal CANADA
Awarded to the PhD dissertation entitled: "Properties and Applications of Rare-Earth-Doped Fiber Amplifiers and Lasers", by Christopher Barnard,
, 1994. Universityof Ottawa
Optical Fiber Communications
1994 WDM Cross-Connected Star Topology for the Bi-Layered ShuffleNet
A WDM cross-connect based on integrating a two-dimensional array of Bragg cells was employed in the design of a Bi-Layered ShuffleNet. The new configuration uses the same configuration as the conventional ShuffleNet, but with addition of another set of connections, achieving a higher efficiency.
· F. Ayadi, J. Hayes, and M. Kavehrad. WDM Cross-Connected Star Topology for the Bilayered Shufflenet. Journal of Lightwave Technology, 12(9):1668--1678, September 1994.
1994 New Optical CDMA Designs to achieve Bipolar Capacity with Unipolar Codes
Solved a fundamental problem that occurs due to insufficient correlation response, in using optical CDMA.
· D. Zaccarin, M. Kavehrad, "New Architecture for Incoherent Optical CDMA to achieve Bipolar Capacity, " Electronics Lett., Vol. 30, No. 3, Feb. 1994.
1993 Optical CDMA System based on Spectral Encoding of LED
Novel and low-cost design of a high-speed optical router / switch with a very-high aggregate throughput. Was commercialized by Code-Stream Inc in CA.
· D. Zaccarin, M. Kavehrad, "An Optical CDMA System Based on Spectral Encoding of LED," IEEE/LEOS Photonics Tech. Lett. Journal, Vol. 5, No. 6, April 1993.
1993 IEEE LEOS Best Student Paper Award in Photonics
IEEE LEOS best student paper award goes to a paper entitled, "An Experiment on a CDM Sub-carrier Multiplexed Optical Fiber Local Area Network," IEEE/LEOS Photonics Technology Letters, July 1992, authored by M. Kavehrad, F. Khaleghi and G. Bodeep. F. Khaleghi received her M.Sc. degree under supervision of Dr. Kavehrad in the year 1992 with a M.S. dissertation entitled: " Spread Spectrum Fiber LANs".
1993 Indoor Infrared Channel Characterization by Measurements
A large set of measurements was taken at the
. By measuring thousands of indoor channel transfer functions in different rooms at different points, we investigated impacts of receiver rotation and shadowing on the properties of indoor infrared channels. A broadband measurement system was designed and developed for use throughout the experiments. Measurement results were used to find and present methods to estimate variations of channel path loss for small changes in the receiver direction, using statistical techniques. Results of this work along with a system design were transferred to the IMAX Corporation for in-theater broadcasting of CD-quality special audio channels to the audience. UniversityOf Ottawa
· H. Hashemi, G. Yun, M. Kavehrad, F. Behbahani, P. Galko, "Indoor Propagation Measurements at Infrared for Wireless Local Area Networks Applications," IEEE Trans. on Veh. Tech., Vol. 43, no. 3, pp. 562-576, Aug. 1994.
· M.R. Pakravan, M. Kavehrad, H. Hashemi, "Indoor Wireless Infrared Channel Characterization by Measurements," IEEE Trans. on Vehicular Tech., Vol.-50, No. 4, July 2001.
1992 Novel Integrated-Optic WDM Cross-Connect
Proposed a novel design for an integrated-optic WDM cross-connect that can be used in various wavelength routing network applications. This subsystem works based on integrating a two-dimensional array of Bragg diffraction cells at cross points of input/output co-planner wave-guides. This work is innovative and in direct response to a significant need in the industrial development of WDM systems. A method for configuring an efficient holographic cross-connect is presented. It makes the construction of a one-piece coupler possible and thus eliminates the excess loss problem associated with cascade couplers and reduces the structural complexity. It is shown that a 100% efficiency figure can be achieved through the entire array by using a properly designed space-varying refractive-index slab. It is demonstrated how a wave-mixing method can be utilized as one possible method of configuring such a cross-connect, using a constant temporal optical frequency involving nonlinear media such as photo-refractive crystals.
For further information see:
· M. Tabiani, M. Kavehrad, M. Irshid, "A Novel Integrated-Optic WDM Cross-Connect for Wide Area All Optical Networks," IEEE/OSA Journal of Lightwave Tech., Vol. 11, No. 3, March 1993.
1992 IEEE LEOS Best Student Paper Award in Photonics
IEEE LEOS best student paper award goes to a paper entitled, "Bi-Directional Fiber Amplifiers," IEEE Photonics Tech. Letters, Vol. 4, No. 8, August 1992, authored by C. Barnard, J. Chrostowski, M. Kavehrad. C. Barnard received his Ph.D. degree under supervision of Dr. Kavehrad in the year 1994 with a PhD dissertation entitled: "Properties and Applications of Rare-Earth-Doped Fiber Amplifiers and Lasers".
1992 Fully Transparent Fiber Ring for WDM Networks
Is one of the first attempts to provide WDM networking on an all-optical ring topology. Idea was implemented in DARPA / Bellcor demonstration projects.
· M. I. Irshid, M. Kavehrad, "A Fully Transparent Fiber-Optic Ring Architecture for WDM Networks," IEEE/OSA Journal of Lightwave Technology, Vol. 10, NO. 1, January 1992, pp. 101-108.
1991 IEEE LEOS Best Student Paper Award in Photonics
IEEE LEOS best student paper award goes to a paper entitled, "Fiber-Optic Transmission of Microwave 64-QAM Signals," IEEE Journal on Selected Areas in Communications, Vol. 8, No. 7, Sept. 1990, pp. 1320-1326, co-authored by E. Savov and M. Kavehrad. E. Savov received his Ph.D. degree under supervision of Dr. Kavehrad in the year 1991 with a dissertation entitled: "Multi-Channel Photonic Networks".
1991 NTT Laboratories visit,
Work on Diversity in Direct Sequence/ Spread Spectrum Mobile Radio, improving the performance.
§ A. Higashi, T. Matsumoto, M. Kavehrad, "Effect of Noise-Only-Paths on the Performance Improvement of Post-Demodulation Selection Diversity in DS/SS Mobile Radio, "IEICE Trans. on Communications (Japan), Vol. E76-B, No. 4, April 1993.
1990 Optical Interconnection Devices, U.S. Patent 5,179,605 and U.S. Patent 5,469,277
Invention and investigation of a wavelength routing star coupler based on holographic gratings. This work is innovative and in direct response to a significant need in the industrial development of WDM systems. A method for configuring an efficient N*N optical passive star coupler is introduced. It makes the construction of a one-piece coupler possible and thus eliminates the excess loss problem associated with cascade couplers and reduces the structural complexity. It is shown that a 100% efficiency figure can be achieved through the entire array by using a properly designed space-varying refractive-index slab. A mathematical analysis of the space-varying refractive-index slab is given and spatial frequencies of the required refractive-index pattern are examined. It is demonstrated how the wave-mixing method can be utilized as one possible method of configuring such a slab, using a constant temporal optical frequency involving nonlinear media such as photo-refractive crystals.
· Optical Interconnection Device (U.S. Patent 5,179,605)
· Optical Interconnection Device (U.S. Patent 5,469,277)
1989 Spot-Diffusing/Direction-Diversity Transceiver for indoor Infrared Communications
[A Multi-Input, Multi-Output (MIMO) System]
Implementation of angle diversity using non-imaging elements requires a separate optical concentrator for each receiving element, which may be excessively bulk and costly. We proposed the fly-eye receiver, which consists of a single imaging optical concentrator (e.g., a lens) that forms an image of the received light on a collection of photo-detectors, thereby separating signals that arrive from different directions. This new design is referred to as an imaging angle-diversity receiver, or simply an imaging receiver. The imaging design has two advantages over a non-imaging angle-diversity receiver. First, all photo-detectors share a common concentrator, reducing the size and the cost. Second, all the photo-detectors can be laid out in a single planar array, facilitating the use of a large number of receiving elements or pixels.
In non-directed, non-LOS links, the conventional diffuse transmitter utilizes a single broad beam aimed at reflecting surfaces within a room, such as the ceiling. We proposed to replace this by the spot-diffusing transmitter, which employs multiple narrow beams pointed in different directions toward these reflecting surfaces. This is referred to as a multi-beam or quasi-diffuse transmitter. While the diffuse transmitter provides considerable immunity against beam blockage near the receiver, it yields a high path loss. The quasi-diffuse transmitter is expected to reduce path loss compared to the diffuse transmitter, because the narrow beams experience little path loss traveling, from the transmitter to the illuminated reflective surfaces.
The pioneering work in this paper, a Multi-Input, Multi-Output (MIMO) architecture, contributed to the use of multi-element antennas at both transmitter and receiver ends for achieving higher capacities over severely band-limited wireless channels, in the RF-MIMO world.
· G. Yun, M. Kavehrad, “Spot Diffusing and Fly-Eye Receivers for Indoor Infrared Wireless Communications," Proceedings of IEEE Wireless Communications Conference Proceedings,
, June 1992. Vancouver
· G. Yun, M. Kavehrad, " Indoor Infrared Wireless Communications Using Spot Diffusing and Fly-Eye Receivers," The Canadian Jour. on Elect & Comp. Eng., Vol. 18, No. 4, October 1993.
1987-91 Optical Transmission of Microwave Signals over Fiber
Bell Labs Technical Report proposing sub-carrier multiplexed 64-QAM over a single-mode fiber. Later, in 1990 Block and Convolutional Codes were introduced to combat the deleterious effects of Relative-Intensity-Noise (RIN). The concept is used today to carry signals between cells in a cellular network.
· M. Kavehrad, A.C. Chipaloski, "Optical Transmission of Microwave 64-Level Quadrature Amplitude Modulated Signals at 1.3 Micron Wavelength," Technical Memorandum, AT&T Bell Laboratories, October 1987.
· M. Kavehrad,
E. Savov, "Fiber-Optic Transmission of Microwave 64-QAM Signals," IEEE Journal on Selected Areas in Communications, Vol. 8, No. 7, Sept. 1990, pp. 1320-1326.
Dr. H. Otsuka, former President and CEO, NTT DoCoMo Beijing Commun. Labs. visited Dr. Kavehrad’s Laboratory to jointly work on:
§ H. Ohtsuka, O. Kagami, S. Komaki, K. Kohiyama, M. Kavehrad, "256-QAM Sub-carrier Transmission Using Coding and Optical Intensity Modulation in Distribution Networks," IEEE/LEOS Photonics Technology Letters, April 1991.
1987 Restoration Free-Space-Optical (FSO) Wireless Links
Bell Labs Technical Reports proposing use of broadband Free-Space-Optical (FSO) wireless links for short ranges between buildings. These have since been manufactured by several companies for providing wireless broadband access and as a means of restoration when fiber links break.
1987 Hybrid Optical & RF Combined Wireless Links
Bell Labs Technical Reports proposing use of broadband access Hybrid Optical & RF Combined Wireless Links for diversity against fading and as a countermeasure against RF interference for short ranges between buildings. See DARPA/ATO BAA-04-03 project, “Optical & RF Combined Link Experiment (ORCLE),” November 2003.
· M. Kavehrad, “A Countermeasure to Improve Outage Performance of Interference-Limited Microwave Radio Links,” Canadian Journal of Electrical & Computer Engineering, Vol. 16, No. 1, January 1991.
· M. Kavehrad, "A Hybrid Radio Model and its Performance in RF Interference Environments," Technical Memorandum, AT&T Bell Laboratories, April 1988.
· M. Kavehrad, "Design and Performance Considerations for the Hybrid Atmospheric Optical/Digital Microwave Network Systems," Technical Memorandum, AT&T Bell Laboratories, December 1987.
1987 Multi-Access Protocols for very High-Speed All-Optical Passive Star LANs,
Bell Labs Technical Report on invention of contention-based multi-access protocols that route information packets optically, on the fly, using a fixed number of available wavelengths in a WDM router. This is one of the first IP based WDM all-optical solutions. Idea was implemented in DARPA demonstration projects.
· I.M. Habbab, M. Kavehrad, C.-E. Sundberg Packet Switched Interconnection Protocols for a Star Configured Optical LAN (U.S. Patent # 4,797,879).
1987 Passive Star Optical LAN Using CSMA/CD, US Patent # 4701909
Bell Labs Technical Report proposing a novel CSMA/CD Optical LAN concept that was later realized by Codenoll Technology Corporation in
. Yonkers, New York
· M. Kavehrad, C.-E. Sundberg, "New Collision Detection Method for a Passive Star Optical Local Area Network using CSMA/CD," US Patent # 4701909, issued
October 20, 1987.
1986 Maximum Entropy and Moments
Bell Labs Technical Report proposes use of Maximum Entropy and the Method of Moments for Evaluation of Probability of Error in Digital Communications. The devised methodology has been extensively used in analysis/design of fiber optic transmission systems.
· M. Kavehrad, M. Joseph, "Maximum Entropy and the Method of Moments in Performance Evaluation of Digital Communication Systems," IEEE Trans. on Communications, pp. 1183-1189, December 1986.
1985 Interference Cancellation and Coding over a (MIMO: Space-Time) Multipath Fading Channels,
The first decision-driven Multi-user Detector reported in the literature appears to be an MMSE detector (U.S. Patent #4,644,562 ) designed to cancel cross-polarization interference over band-limited multipath fading transmission channels in a Multi-Input-Multi-Output (MIMO) Space-Time configuration†.
† Sergio Verdu, Multiuser Detection,
Press, pp.-386, 1998. Cambridge Univ.
See also, the GLOBECOM’95 PAPER by Dr. John Barry -- Georgia Tech., 1995.
At about the same time, work was continued into Combined QAM and Trellis codes for cross-coupled Multidimensional Channels.
· M. Kavehrad, " Baseband Cross-Polarization Interference Cancellation for M-Quadrature Amplitude Modulated Signals over Multipath Fading Radio Channels," AT&T Technical Journal, Vol. 64, No. 8, pp. 1913-1926, October 1985.
· M. Kavehrad, J. Salz," Cross-Polarization Cancellation and Equalization in Digital Transmission Over Dually-Polarized Multipath Fading Channels," AT&T Technical Journal, Vol. 64, No. 10, December 1985. Also, see U.S. Patent # 4,644,562.
· M. Kavehrad, P.J. McLane and C-E. Sundberg, "On the Performance of Combined QAM and Convolutional Codes for Cross-Coupled Multidimensional Channels," IEEE Trans. on Communications, pp. 1190-1201, December 1986.
· M. Kavehrad and C-E. Sundberg, "Bit Error Probability of Trellis-Coded Quadrature Amplitude Modulation Over Cross-Coupled Multidimensional Channels," IEEE Trans. on Communications, pp. 369-381, April 1987.
1984 Spread-Spectrum Indoor Wireless (W-CDMA), US Patent # 4,672,658
In several Bell Labs papers and by a real feasibility model development, we proposed one of the first wideband direct-sequence spread spectrum (W-CDMA) wireless systems with CDMA base-stations for voice/data transmissions inside the buildings (Origins of Hot-Spots and WiFi). This was well before the activities of Qualcomm Inc and other companies on CDMA access in mobile cellular and wireless LANs applications.
These works, as said by the FCC rule makers, speeded up the FCC allocation of the ISM bands. The 802.11b standard has its roots back in these works, as well.
At the time, these were daunting tasks to take on at Bell Labs. Later, many industries followed these pioneering works to product level.
The June 1987 IEEE Communications Magazine Guest Editorial started a series of articles that shed some light on the confusions within the
and Portable Communications community, at the time. Mobile
· US Patent # 4,672,658, Spread Spectrum Wireless PBX.
· M. Kavehrad, B. Ramamurthi, "Direct-Sequence Spread Spectrum with DPSK Modulation and Diversity for Indoor, Wireless Communications," IEEE Trans. on Communications, February 1987, pp. 224-236.
· M. Kavehrad, G.E. Bodeep, "Design and Experimental Results for a Direct-Sequence Spread-Spectrum Radio using Differential Phase Shift Keying Modulation for Indoor, Wireless Communications," IEEE Journal on Selected Areas in Communications, June 1987, pp. 815- 823.
· M. Kavehrad, P.J. McLane, "Performance of Low-Complexity Channel-Coding and Diversity for Spread-Spectrum in Indoor, Wireless Communication," AT&T Technical Journal, Vol. 64, No. 8, October 1985, pp. 1927-1966.
· M. Kavehrad, "Performance of Non-diversity Receivers for Spread Spectrum in Indoor Wireless Communications," AT&T Technical Journal, Vol. 64, No. 6, Part-1, July-August 1985, pp. 1181-1210.
· M. Kavehrad, P.J. McLane, "Spread Spectrum for Indoor Digital Radio," IEEE Communications Magazine, June 1987, pp. 32-40.
1982 A Class of Convolutional Codes for High-Speed Digital-Radio
Bell Labs Technical Report offers a detailed design of High-Efficiency Codes used in ATT DR4 and DR6 Microwave Digital Radios.
· M. Kavehrad, "Convolutional Coding for High-Speed Microwave Radio Communications," AT&T Technical Journal, Vol. 64, No. 7, pp. 1625-1638, September 1985.
1981 CDMA Packet Radio Network
GTE Labs Technical Report proposes use of and evaluates throughput/delay performance of CDMA packet radios having fixed or mobile access to portable handheld computing devices. Many companies now manufacture wireless palmtops.
· M. Kavehrad, "An Accessing Technique for Information Packet Networks," Proceedings of EASCON,
, November 1981. Washington, D.C.
1979 Packet Switched Satellite Communications
GTE Labs. Technical Report proposes use of and evaluates performance of Packet Switched Satellite Access to portable handheld computing and communications devices. Many companies now manufacture such systems.