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MRS Online Proceedings Library 1997年第1期482卷 648-659页

作者： S. Cmchibu T. Deguchi T. Sota K. Wada S. Nakamura Materials Department University of California Santa Barbara USA Faculty of Science and Technology Science University of Tokyo Chiba 278 Japan Department of Electrical Electronics and Computer Engineering Waseda University Tokyo 169 Japan Compound Semiconductor Materials Research NTT System Electronics Laboratories Kanagawa Japan Department of Research and Development Nichia Chemical Industries Ltd. Tokushima 774 Japan

Emission mechanisms of the device-quality quantum well (QW) structure and bulk three dimensional (3D) InGaN materials grown on sapphire substrates without any epitaxial lateral overgrown GaN (ELOG) base layers were investigated. The InxGx1−xN layers showed various degree of spatial potential (bandgap) fluctuation, which is probably due to a compositional inhomogeneity or monolayer thickness fluctuation produced by some kinetic driving forces initiated by the threading dislocations (TDs) or growth steps during the growth. The degree of fluctuation changed remarkably around nominal InN molar fraction x=0.2, which changes to nearly 8–10 % for the strained InxGa1−xN. This potential fluctuation induces energy tail states both in QW and 3D InGaN, showing a large Stokes-like shift combined with the red shift due to quantum confined Stark effect (QCSE) induced by the piezoelectric field. The spontaneous emission from undoped InGaN single quantum well (SQW) light-emitting diodes (LED’s), undoped 3D double heterostructure (DH) LED’s, and multiple quantum well (MQW) laser diode (LD) wafers was assigned as being due to the recombination of excitons localized at the potential minima, whose area was determined by cathodoluminescence (CL) mapping to vary from less than 60 nm to 300 nm in lateral size in the case of QW’s. The lasing mechanisms of the cw In0.15Gao.85N MQW LD’s having small potential fluctuation, whose bandgap broadenings are less than about 50 meV, can be described by the well-known electron-hole-plasma (EIHP) picture with Coulomb enhancement. The inhomogenous MQW LD’s are considered to lase by EHP in segmented QW’s or Q-disks. It is desirable to use entire QW planes with small potential inhomogeneity as gain media for higher performance LD operation.

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A multiple-channel free-access collision resolution algorithm based connection request procedure for land mobile satellite networks

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INTERNATIONAL JOURNAL OF SATELLITE communications 1996年第4期14卷 313-325页

作者： Tan, HH Yan, TY Electrical and Computer Engineering Department University of California Irvine Irvine CA?92717 U.S.A Communications System Research Section Jet Propulsion Laboratories 4800 Oak Grove Drive Pasadena CA?91109 U.S.A. [*]Electrical and Computer Engineering Department University of California Irvine Irvine CA?92717 U.S.A

A new binary feedback multiple-channel free-access (MCFA) collision resolution algorithm (CRA) based random-access protocol (RAP) is devised to implement the connection request procedure for demand-assigned channel access protocols in land mobile satellite communications networks. The maximum stable throughput of this protocol is derived and is shown to be superior to a previously devised multiple-channel obvious blocked-access CRA based RAP as well as to slotted ALOHA. The throughput performance is also superior to the previously devised multiple-channel window blocked-access CRA based RAP for four or more channels. An exact analysis of the average packet delay for this MCFA CRA based RAP is given and shown to be in excellent agreement with computer simulation results, The protocol is shown to have smaller average delays than the best single-channel free access CRA based RAPs over a wide range of practically usable throughput rates with reasonable delays. This MCFA CRA based RAP was implemented on a channel request protocol test-bed simulator which incorporates the physical link characteristics of the MSAT-X land mobile satellite system. These testbed simulation results also demonstrate the superiority of this protocol over slotted ALOHA for both error-free channel and mobile facing channel scenarios.

关键词： mobile satellite networks demand assigned protocols collision resolution algorithms

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Adaptability of K-L expansion technique for ambiguous face image retrieval

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ELECTRONICS AND communications IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE 1996年第10期79卷 35-46页

作者： Oda, M Akamatsu, S Fukamachi, H ATR Human Information Processing Laboratories Kyoto Japan 619-02 Shigeru Akamatsu received his B.E. M.E. and Dr. of Eng. degrees in Mathematical Enginwring and Instrumentation Physics in 1975 1977 and 1994 respectively from the University of Tokyo Japan. In 1977 he joined the Electrical Communications Laboratories Nippon Telegraph and Telephone Public Corporation Yokosuka Japan. From 1977 through 1985 he was engaged in the research and development of optical character recognition systems for handwritten Chmese characters. During the academic year 1985-86 he was a Visiting Researcher at the University of California Irvine California U.S.A. Until 1992 he was a Senior Research Engineer Supervisor at W Human Interface Laboratories and conducted research on human image recognition with a special interest in face recognition. Since 1992 he has been with ATR Human Information Processing Research Laboratories Kyoto Japan where he is currently Head of Department 2. His research interests include computational and cognitive studies on high-level vision with a special interest in facial information processing by man and computer. He is a member of the Institute of Electronics Information and Communication Engineers of Japan the Information Processing Society of Japan ACM and the IEEE Computer Society. Hidm Fukamachi received his B.E. degree in Image Technology from the Tokyo Institute of Polytechnics in 1990. He joined NTT Software Corp. in 1990 where he was engaged in the development of image processing software. Since 1993 he has been with ATR Human Information Processing Research Laboratories.

Some facial images are not necessarily clear images in the human brain. However, it can be easily judged whether a face matches the image in our mind;this is true even when the drawing or the expression of the target image is difficult to comprehend. This is because even if the image cannot be imagined like a picture, it does exist. The authors have proposed a system with which a retriever can retrieve an ambiguous target image from an image database. The system's retrieval efficiency and ease-of-retrieval were clarified by experiments using line drawn facial images. In this paper, the system is extended to photographs of faces. The most difficult problem in treating photographs is determining the retrieval key. One consideration is to add the subjective impressions or features of physical figures as keywords for each image data. Regardless of the method, however, significant manpower is necessary. The K-L expansion technique is used here, which has been verified as effective for face identification, and expect to need only a small amount of manpower. This paper investigates whether the technique can also be useful in ambiguous image retrieval.

关键词： ambiguous image image retrieval K-L expansion facial image subjective similarity

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A MULTIPLE-CHANNEL FREE-ACCESS COLLISION RESOLUTION ALGORITHM BASED CONNECTION REQUEST PROCEDURE FOR LAND MOBILE SATELLITE NETWORKS

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International Journal of Satellite communications and Networking 1996年第4期14卷

作者： HARRY H. TAN TSUN-YEE YAN Electrical and Computer Engineering Department University of California Irvine Irvine CA 92717 U.S.A Communications System Research Section Jet Propulsion Laboratories 4800 Oak Grove Drive Pasadena CA 91109 U.S.A.

A new binary feedback multiple-channel free-access (MCFA) collision resolution algorithm (CRA) based random-access protocol (RAP) is devised to implement the connection request procedure for demand-assigned channel access protocols in land mobile satellite communications networks. The maximum stable throughput of this protocol is derived and is shown to be superior to a previously devised multiple-channel obvious blocked-access CRA based RAP as well as to slotted ALOHA. The throughput performance is also superior to the previously devised multiple-channel window blocked-access CRA based RAP for four or more channels. An exact analysis of the average packet delay for this MCFA CRA based RAP is given and shown to be in excellent agreement with computer simulation results. The protocol is shown to have smaller average delays than the best single-channel free access CRA based RAPs over a wide range of practically usable throughput rates with reasonable delays. This MCFA CRA based RAP was implemented on a channel request protocol test-bed simulator which incorporates the physical link characteristics of the MSAT-X land mobile satellite system. These test-bed simulation results also demonstrate the superiority of this protocol over slotted ALOHA for both error-free channel and mobile facing channel scenarios.

关键词： mobile satellite networks demand assigned protocols collision resolution algorithms

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A METHOD FOR PREDICTING CHAOTIC TIME-SERIES WITH OUTLIERS

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ELECTRONICS AND communications IN JAPAN PART III-FUNDAMENTAL ELECTRONIC SCIENCE 1995年第5期78卷 44-53页

作者： ITOH, K Member NTT Communication Science Laboratories Yokosuka Japan 238-03 Ken-ichi Itoh received his B.E. degree in 1969 from the Department of Electrical Engineering Kyushu Institute of Technology and affiliated with NTT. He is engaged in research and development of computer hardware systems. At present he is Senior Research Engineer Supervisor NTT Communications Science Laboratories. He is a member of the Information Processing Society.

In recent years, there have been intensive studies on the short-term, prediction method for time-series data with chaotic properties. The prediction for the chaotic time-series data is executed, for example, as follows. Based on the single-variable time-series data, the trajectory of the attractor is reconstructed in the multidimensional space and the change of the trajectory is predicted by a polynomial approximation. However, when there exists a noise such as the outlier in the time-series, the prediction error is increased drastically. To solve this problem, this paper proposes a prediction method which is robust against the outlier. More precisely, the following three elaborations are added to the conventional method: (1) the coefficients of the polynomial are calculated by Biweight's estimation method;(2) the order of the polynomial is determined automatically examining the residual error;and (3) the data with a large prediction error are replaced by the predicted value and the next prediction is applied. An evaluation experiment is executed for the data where the pseudorandom variable with the Cauchy distribution is superposed on the chaotic time-series data generated by the Henon map and the Lorenz model. It is verified as a result that the proposed method can well suppress the increase of the prediction error due to the outliers, improving greatly the accuracy of the prediction compared to the conventional method.

关键词： CHAOS PREDICTION TIME-SERIES LEAST-SQUARES METHOD OUTLIER

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ISDN LOOP EXTENSION USING A MID-SPAN AMPLIFIER

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INTERNATIONAL JOURNAL OF COMMUNICATION systemS 1995年第3期8卷 219-224页

作者： ERKER, GJ DODDS, DE KRZYMIEN, WA David E. Dodds was born in Saskatoon Canada in 1945. He received the B. Eng. and MSc. degrees from the University of Saskatchewan in 1966 and 1968 respectively. He worked with Bell Northern Research (Ottawa) on PBX design in 1969 1972 and 1978. Since 1969 he has been with the University of Saskatchewan where he is currently Professor of Electrical Engineering. He teaches courses in electronics and communications and also presents short courses on the fundamentals of telephony. Current research interests are in data transmission signal processing architecture and frame synchronization for PCM and spread spectrum systems. He has been granted five patents relating to commercial products in delta-modulation telephone line interfacing and computer data transmission. In 1986 he was on sabbatical leave at BNR Inc. and worked with an ANSI committee on the standardization of FDDI-II a combined voice and data system. Mr. Dodds is a Registered Consulting Engineer in Saskatchewan. Witold A. Krzyden received his MSc. (Eng.) and Ph.D. degrees (both in Electrical Engineering) in 1970 and 1978 respectively from the Poznan Technical University in Poznan Poland. He was awarded the Minister's of Science and Technology Prize of Excellence for his Ph.D. thesis. From 1970 to 1978 he was a Research Engineer and Teaching Assistant and then from 1978 to 1980 an Assistant Professor of Electrical Engineering at the Poznan Technical University. In 1980 he won a Dutch Government Research Fellowship at the Twente University of Technology in Enschede the Netherlands for the year of 1980/1981. In the following year of 1981/82 he was a Research Assistant Professor there. From 1982 to 1986 he was an Assistant Professor of Electrical Engineering at Lakehead University in Thunder Bay Ontario Canada. In 1986 he joined the Univeristy of Alberta and Alberta Telecommunications Research Centre (now Telecommunications Research Laboratories or TRLabs) as an Associate Professor of Electrical Engineering. Currently he is a Professor of E

The 5.5 km range of the basic rate ISDN loop has been extended by using a negative impedance amplifier and by using a 2 wire/4 wire (2w/4w) amplifier. The negative impedance amplifier extends the range of the loop by 1.0 km, whereas the 2w/4w amplifier extends the range by 1.5 km at the expense of increased complexity. As part of the amplifer design, a resistor/capacitor network has been developed which closely matches the characteristic impedance of telephone cable. Error rate tests have been conducted using various lengths of cable and an operating ISDN line.

关键词： ISDN PHYSICAL LAYER BASIC RATE LOOP RANGE EXTENSION

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PERFORMANCE OF A PRIORITIZED ON-BOARD BASEBAND SWITCH FOR A MULTISERVICE MULTIBEAM SATELLITE

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INTERNATIONAL JOURNAL OF SATELLITE communications 1994年第3期12卷 283-297页

作者： BOHM, S ELHAKEEM, AK HACHICHA, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada An Associate Director of Advanced Technology & Networks Group VISTAR Telecommunications Inc. Ottawa Canada. He is also an Adjunct Pr

In this paper, we study the performance of a prioritized on-board baseband switch in conjunction with a multibeam satellite handling integrated services. The services considered for the analysis include voice, video, file transfer and interactive data. The prioritized switch uses both input and output buffering, switch speed-up as well as a two-phase head-of-line resolution algorithm, in order to reduce the buffer loss while maintaining acceptable user delays. The minimum required buffer capacity and switch speed-up for each service in a prioritized environment are found under uniform traffic conditions. It is shown that under uniform traffic conditions, only minimal buffering and switch speed-up are needed even for the lowest priority users. The performance dependence on the switch size is also substantially reduced with head of line resolution and buffering even in a prioritized environment.

关键词： SWITCH ON-BOARD BASEBAND MULTIBEAM PRIORITIZED HEAD-OF-LINE UNIFORM LOAD SPEED-UP

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ANALYSIS OF A MOVABLE BOUNDARY ACCESS TECHNIQUE FOR A MULTISERVICE MULTIBEAM SATELLITE system

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INTERNATIONAL JOURNAL OF SATELLITE communications 1994年第3期12卷 299-312页

作者： BOHM, S ELHAKEEM, AK MURTHY, KMS HACHICHA, M KADOCH, M Department of Electrical and Computer Engineering Concordia University 1455 De Maisonneuve Blvd. West Montreal H3A 1M8 Canada Was born in Montreal Canada on 14 September 1966. He received the B. Eng. degree in electrical engineering from Concordia University Montreal Canada in 1989. He is at present completing the M.A.Sc. degree in electrical engineering at Concordia University. (S'75–S'79–M'79–SM'86) received the Ph.D. degree from Southern Methodist University Dallas TX in 1979. He spent the next two years working as a Visiting Professor in Egypt after which he moved to Ottawa Canada in 1982. He assumed teaching and research positions in Carleton and Manitoba Univerities and later moved to Concordia University Montreal Canada in 1983 where he is now a Professor in the Electrical and Computer Engineering Department. He has published numerous papers in IEEE and international journals in the areas of spread spectrum and networking. He is a well-known expert in these areas and serves as a consultant to many companies. His current research interests include wide-band metropolitan networks switching architectures and performance of on-board multibeam satellites acquisitionless CDMA networks code distribution and orthogonalization of CDMA signals responsive congestion control for ATM-based networks ARQ techniques and investigation of the novel SUGAR CDMA systems in fading channels. Dr. Elhakeem is a Senior Member of the Canadian Electrical Engineering Society and Armed Forces Association. He has chaired numerous technical sessions in IEEE Conferences was the Technical Program Chairman for IEEE Montech 1986 Montreal Canada. Dr. Elhakeem is the key guest editor of theIEEE Journal of Selected Areas in Communicationsfor the May June issues 1993 covering CDMA networks. Advanced Technology & Networks VISTAR Telecommunications Inc. Ottawa Ontario K1G 3J4 Canada . He is ITU's Specialist Consultant and Chief Advisor for a number of ITU/UNDP projects including VSATs Rural Networks Digital Broadc

In this paper, the performance of a new movable boundary accessing (MBA) technique for future integrated services multibeam satellite systems is studied. The multiservice environment considered includes both asynchronous and isochronous traffic consisting of video, voice, file transfer and interactive data. The movable boundary access technique proposed here will maximize the utilization of the up-link frame capacity. It is shown that the potential user population is substantially increased with the use of a moving boundary policy with minimal overhead.

关键词： MOVABLE BOUNDARY ACCESS TECHNIQUE MF-TDMA DAMA MULTIBEAM SATELLITE

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TECHNICAL ISSUES REGARDING SATELLITE PACKET-SWITCHING

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INTERNATIONAL JOURNAL OF SATELLITE communications 1994年第3期12卷 257-267页

作者： IVANCIC, WD CHU, P SHYY, DJ National Aeronautics and Space Administration Lewis Research Center Cleveland Ohio 44135 USA. A design engineer in the Digital Technology Branch of the Space Electronics Division. He has extensive experience in satellite communications systems modulation and coding on-board switching and routeing and high speed digital design. Since joining NASA in 1982 Mr. Ivancic has been responsible for the development of a variety of matrix switch controllers ground terminal equipment numerous pieces of special test equipment a beacon controller for the SARSAT program (Search and Rescue Satellite) and a time-shared decoder for a processing satellite. In addition Mr. Ivancic has been technical contract monitor on a number of advanced communications technology contracts including the Advanced Modulation Technology Development a 5 GHz fibre-optic link and multi-programmable modem study. He was awarded the B.S.E.E. and M.S.E.E. degrees by Cleveland State University in 1982 and 1986 respectively. Cleveland State University Cleveland Ohio 44115 USA. Currently an assistant professor of Electrical Engineering Department at Cleveland State University. He obtained the M.S. and Ph.D. degrees from Iowa State University majoring in Electrical and Computer Engineering. His research interests include high-speed computer networks digital systems and neural networks applications. He is a member of Sigma Xi Phi Kappa Phi as well as the IEEE and ACM. ComSearch Reston Virginia 22091 USA. Received the B.S. degree in electrical engineering from National Chiao-Tung University Hsin-Chu Taiwan in 1983 and the M.S. and Ph.D. degrees in electrical engineering from Georgia Institute of Technology Atlanta GA in 1986 and 1990 respectively. From June 1987 to October 1987 he worked for the Department of Neurology Emory University Atlanta as a Programmer. From September 1989 to December 1989 he worked for the Advanced Development Laboratory. AMP Inc. Atlanta as a Test Engineer. From February 1990 to August 1993 he wor

Many concepts for advanced communication satellite networks have recently been proposed. Critical technical issues relating to satellite packet switching for meshed very small aperture terminal networks and broadband ... 详细信息

关键词： FAST PACKET SWITCH BISDN MESHED VSAT ON-BOARD PROCESSING

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Guest Editorial: Focus on Digital Signal Processing Techniques Applied to Space communications

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European Transactions on Telecommunications 1993年第1期4卷 9-10页

作者： Gaudenzi, Riccardo De Elia, Carlo Harris, Robert A. Rimrdo De Gaudend was born in Rosignano Mmo Italy in 1960. He received the Doctor En- gineer degree (cum Laude) in Electronic Engineering from the University of Pisa. Italy in 1985. From 1986 he was with the European Space Agency (ESA). Stsliow and Communications Engineering Department. Darmrtadt (RFA) where he was involved in satellite telecommunication ground systems design and testing. In particular he followed the development of two new ESA's satellite tracking systems. In 1988 be joined the ESA's Research and Technology Centre (ESTEC). Noordwijk. The Netherlands where is holding a position as releeommunication enginm in the Electrical System Department. He is presently responsible for the definition and development of advanced satellite communication systems. His mull intenst b ddyrducd with effacnt digital modulation and access techniques for fued and mobile wtdlite services synchronization topics and communication systems simulation techniques. Carlo Elia (S'89) was born in Trepuzzi. Italy in 1964. He received the Doctor Engineer degree in Electronic Engineering from Politecnico di Torino. Torino. Italy. in 1989. He his now attending a Doctorate program at PolitanieO di Torino. S i 1990. he has been with the Eurpean Space Agency (ESA) in the Electrical System Department as Tdeeommunications Syrtcm Engineer. His main areas of interest are related to rdvanccd digital modulation and access techniques and channel equalization. R.A. (Bob) Harris (S'69–M'70) received the PhD from the University of Southampton. England in 1971. In 1970 he joined the European Space Agency (then ESRO). based at the European Space Research and Technology Centre (ESTEC) Noordwijk. The Netherlandswas working on telemetry and telecommand systems. Since 1978 he has been Head of the Transmision Techniques Section in the Directorate of Telecom munications. He was involved in the transmission design of the OTS ECS Olympus and European Data Relay systems. He has worked on a wide range of analogue and digital transmission topics wit

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