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TECHNICAL ISSUES REGARDING SATELLITE PACKET-SWITCHING

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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IMPORTANCE SAMPLING METHODOLOGIES FOR SIMULATION OF COMMUNICATION-SYSTEMS WITH TIME-VARYING CHANNELS AND ADAPTIVE EQUALIZERS

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IEEE JOURNAL ON SELECTED AREAS IN communications 1993年第3期11卷 317-327页

作者： ALQAQ, WA DEVETSIKIOTIS, M TOWNSEND, JK Center of Communications and Signal Processing Department of Electrical and Computer Engineering North Carolina State University Raleigh NC USA

Formula-based analysis of communication links with time-varying channels and adaptive equalizers is not always tractable-Monte Carlo simulation must be used to obtain bit error rate (BER) estimates of the system. Conventional Monte Carlo simulation will not provide estimates for low BER's due to excessive run time. Although importance sampling (IS) techniques offer the potential for large speedup factors for BER estimation using MC simulation, IS techniques have not been used for simulating communication links with adaptive equalizers. In this paper, we present (for the first time) two IS methodologies for MC simulation of communication links characterized by time-varying channels and adaptive equalizers. One methodology is denoted as the ''twin system'' (TS) method. A key feature of the TS method is that biased noise samples are input to the adaptive equalizer, but the equalizer is only allowed to adapt to these samples for a time interval equal to the memory of the system. In addition to the TS technique, we also present a statistically biased, but simpler, technique for using IS with adaptive equalizers which is based on the independence assumption between equalizer input and equalizer taps (the ''IA'' method). Experimental results are presented that show run-time speedup factors of two to seven orders of magnitude for a static linear channel with memory, and of two to almost five orders of magnitude for a slowly-varying random linear channel with memory for both the IA and TS methods.

关键词： Telecommunication links COMMUNICATION SYSTEMS adaptive equalisers importance sampling Equalizers TBXAS1 gene HELIOS DEVICES INFORMATION ASSURANCE linear channel time-varying channels Cache Memory System T-method CACNA1C gene transport stream

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GENERALIZED ADAPTIVE NEURAL FILTERS

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ELECTRONICS LETTERS 1993年第4期29卷 342-343页

作者： ANSARI, N ZHANG, ZZ Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology Newark USA

A new nonlinear filter known as the generalised adaptive neural filter (GANF) is introduced. It is extended from the generalised stack filter and can be adapted by various neural networks. It is also shown that there always exists a GANF that can achieve an absolute error less than or equal to that of a stack filter with the same window width. Experimental results are presented to demonstrate the effectiveness of GANF for suppressing noise.

关键词： NEURAL NETWORKS FILTERS ADAPTIVE FILTERS

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AN OBJECTIVE PERFORMANCE-MEASURE IN MULTIRESOLUTION signal DECOMPOSITION

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IEEE TRANSACTIONS ON signal processing 1993年第11期41卷 3153-3157页

作者： AKANSU, AN CAGLAR, H LIU, YP Department of Electrical and Computer Engineering Center for Communications and Signal Processing Research New Jersey Institute of Technology Newark NJ USA

This correspondence presents an analysis of band energies and evaluates the effects of aliasing in perfect reconstruction (PR) multirate systems. An objective performance measure called nonaliasing energy ratio (NER) is defined. The merit of the new measure is emphasized with the performance comparisons of popular block transforms and 2-band PR-QMF based hierarchical filter banks. It is shown that the new measure complements the widely used energy compaction measure.

关键词： signal resolution Filter bank Frequency Energy measurement Matrix decomposition Energy resolution Interpolation Band pass filters Compaction signal processing

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PRIORITY SHAPING OF SOURCE TRAFFIC IN ATM B-ISDN

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computer communications 1993年第12期16卷 794-797页

作者： REISS, LK MERAKOS, LF [a]Communications Digital Signal Processing Research Center Electrical Computer Engineering Department Northeastern University Boston MA 02115 USA

A source traffic shaper based on prediction of the behaviour of the ATM B-ISDN access policer is discussed. Using this approach, it is possible, within a policed virtual circuit, to reduce both loss and delay of the high-priority cells at the expense of delay of the low-priority cells. The priority-based traffic shaping is beneficial for sources generating cell streams with differing service requirements, e.g. multimedia sources.

关键词： TRAFFIC SHAPING ATM B-ISDN

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LANDMARK-BASED SHAPE-RECOGNITION BY A MODIFIED HOPFIELD NEURAL-NETWORK

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PATTERN RECOGNITION 1993年第4期26卷 531-542页

作者： ANSARI, N LI, K Center for Communications and Signal Processing Department of Electrical and Computer Engineering New Jersey Institute of Technology University Heights Newark NJ 07102 U.S.A

A new method to recognize partially visible two-dimensional objects by means of a modified Hopfield neural network is introduced. Each object is represented by a set of ''landmarks'', and thus such an approach is referred to as landmark-based shape recognition. The landmarks of an object are points of interest relative to the object that have important shape attributes. Given a scene consisting of partially visible objects, a model object in the scene is determined by how well the model landmarks are matched to those in the scene. A local shape measure, known as the sphericity, is used to measure the similarity between two landmarks. The hypothesis of a model object in a scene is made by matching the model landmarks with the scene landmarks. The landmark matching task is performed by a modified Hopfield neural network. The location of the model in the scene is estimated by a least squares fit among the matched landmarks. The hypothesis is finally verified by a heuristic measure. The convergence of the modified Hopfield neural network is proven, and the robustness of the approach has been experimentally demonstrated.

关键词： OCCLUSION LANDMARKS SHAPE RECOGNITION SPHERICITY HOPFIELD NET ENERGY FUNCTION NEURAL NETWORKS

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MULTITARGET TRACKING IN CLUTTER - FAST ALGORITHMS FOR DATA ASSOCIATION

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IEEE TRANSACTIONS ON AEROSPACE AND ELECTRONIC SYSTEMS 1993年第2期29卷 352-363页

作者： ZHOU, B BOSE, NK Department of Electrical and Computer Engineering the spatial and temporal signal processing center Pennsylvania State University University Park PA USA

Three fast algorithms have been developed to solve the problem of data association in multitarget tracking in clutter. In the first algorithm, the problem of data association is identified as an exhaustive search problem in general. Subsequently, a mathematical model is proposed for the problem of data association in the joint probabilistic data association filter (JPDAF). Based on the model, a depth-first search (DFS) approach is developed for the fast generation of data association hypotheses and the computation of the conditional probabilities of the hypotheses in the JPDAF. When the density of targets is moderate, a second algorithm which is more efficient is developed to directly compute a posteriori probabilities in the JPDAF without generating the data association hypotheses. In the third algorithm, the effect of interference due to closely spaced targets is simplified. This leads us to develop an approach to approximately compute the a posteriori probabilities in the JPDAF. The computational complexity of the above algorithms is analyzed in the worst case as well as in the average case.

关键词： data association algorithms clutter multiple target tracking a posteriori probability

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ASYNCHRONOUS TRANSFER MODE (ATM) OPERATION VIA SATELLITE - ISSUES, CHALLENGES AND RESOLUTIONS

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INTERNATIONAL JOURNAL OF SATELLITE communications 1994年第3期12卷 211-222页

作者： CHITRE, DM GOKHALE, DS HENDERSON, T LUNSFORD, JL MATHEWS, N COMSAT Laboratories 22300 Comsat Drive Clarksburg MD 20871 USA. Received his B.Sc. from the University of Bombay India an M.A. in mathematics from the University of Cambridge U.K. and a Ph.D. in physics from the University of Maryland. He is currently an Associate Executive Director of the Network Technology Division at COMSAT Laboratories. He has been involved in research and development activities in ISDN VSAT networks data communications and network systems and architectures. Prior to his current positions Dr. Chitre was a Principal Scientist in the Network Technology Division at COMSAT Laboratories. Dr. Chitre joined COMSAT Laboratories in 1980. He has made major contributions to the analysis and architecture of data communication ISDN and BISDN via satellite. Dr. Chitre directs and participates in the international and national standards activities in ISDN BISDN and data communication as they apply to satellite communication. He was Chairman of the Working Group on Protocols and Network Timing Function of the CCIR/CCITT Joint Ad Hoc Group on ISDN-Satellite Matters during 1990–1992. Currently he is the Chairman of the Working Group on New Technologies in the ITU Intersector Coordinating Group (ICG) on Satellite Matters. Dr. Chitre was a programme manager during 1990 and 1991 on a contract from INTELSAT on systems studies on satellite communications systems architectures for ISDN and broadband ISDN systems. Currently he is the technical manager of the DoD Contract on ATM via satellite demonstration and the programme manager for the INTELSAT contract on analysis and top-level specification of INTELSAT ISDN subnetworks and SDH compatible transport network. Department manager for ISDN/Data Communications in the Network Technology Division of COMSAT Laboratories. His responsibilities include managing the implementation of next generation telecommunication systems for fixed and mobile satellite systems. Current projects include the development of a high data rate gateway switch that provides for the

Key issues regarding the operation of the broadband integrated services digital network (BISDN) via satellite are presented herein. The specific issues, challenges, and their resolutions are detailed. In particular, the impact of error characteristics and propagation delay on the operation of BISDN via satellite is discussed. Solutions are presented for removing adverse effects and providing high-quality service to users of BISDN via satellite.

关键词： ATM BISDN

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SIMPLIFICATION OF A MULTIDIMENSIONAL DIGITAL-FILTER STABILITY TEST

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JOURNAL OF THE FRANKLIN INSTITUTE-engineering AND APPLIED MATHEMATICS 1993年第5期330卷 905-911页

作者： BOSE, NK Department of Electrical and Computer Engineering Spatial and Temporal Signal Processing Center The Pennsylvania State University University Park PA 16802 USA

The complexity of computation in a multidimensional digital filter stability test using resultant theory is reduced by exploiting a criterion for a polynomial having complex coefficients to be a Schur polynomial. The computational advantage is illustrated by nontrivial examples involving polynomials having both numerical and literal coefficients.

关键词： Digital filters

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RECURSIVE TOTAL LEAST-SQUARES ALGORITHM FOR IMAGE-RECONSTRUCTION FROM NOISY, UNDERSAMPLED FRAMES

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MULTIDIMENSIONAL SYSTEMS AND signal processing 1993年第3期4卷 253-268页

作者： BOSE, NK KIM, HC VALENZUELA, HM 1. Department of Electrical and Computer Engineering The Spatial and Temporal Signal Processing Center The Pennsylvania State University 16802 University Park PA

It is shown how the efficient recursive total least squares algorithm recently developed by C. E. Davila [3] for real data can be applied to image reconstruction from noisy, undersampled multiframes when the displacement of each frame relative to a reference frame is not accurately known. To do this, the complex-valued image data in the wavenumber domain is transformed into an equivalent real data problem to which Davila's algorithm is successfully applied. Two detailed illustrative examples are provided in support of the procedure. Similar reconstruction in the presence of blur as well as noise is currently under investigation.

关键词： IMAGE RECONSTRUCTION RECURSIVE TOTAL LEAST SQUARES ALGORITHM IMAGE SEQUENCE MULTIPLE FRAMES INTERPOLATION FILTERING

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