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IEEE Conference on Vehicular Technology (VTC)

作者： J. Luo J. Zeidler S. McLaughlin Department of Electrical & Computer Engineering University of California San Diego La Jolla CA USA SPAWAR Systems Center San Diego USA Hughes Network Systems Inc. Department of Electronics & Electrical Engineering University of Edinburgh UK

This paper presents the average error probability performance of a compact space diversity receiver for the reception of coherent binary PSK signals through a correlated Nakagami (1960) fading channel. Analytical expression of the average BER is derived as a function of the covariance matrix of the multipath component signals at the antenna elements. The sensitivity of the performance to the operating environment (fading, angular spread, mean angle-of-arrival and input branch SNR) and the antenna array configuration (diversity order, antenna separation and electromagnetic coupling) is investigated.

关键词： Sensitivity analysis Antenna arrays Fading Error probability Phase shift keying Signal analysis Bit error rate Covariance matrix Antenna accessories Electromagnetic coupling

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Performance evaluation of line drawing recognition systems

Performance evaluation of line drawing recognition systems

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International Conference on Pattern Recognition

作者： A.K. Chhabra I.T. Phillips Bell Atlantic Network Systems Advanced Technology White Plains NY USA Computer Science Software Engineering Department Seattle University Seattle WA USA

ISBN: (纸本)0769507506

Presents the results of the third international graphics recognition contest. We evaluated the performance of four different vectorization systems on scanned images of CAD drawings. The EditCost Index was used for comparative evaluation of the systems. The performance curves of the systems on the test images are presented in this paper.

关键词： engineering drawings System testing Image recognition Image converters computer graphics Image generation computer science Software engineering Time measurement Noise generators

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On distributed, geographic-based packet routing for LEO satellite networks

On distributed, geographic-based packet routing for LEO sate...

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IEEE Conference and Exhibition on Global Telecommunications (GLOBECOM)

作者： T.R. Henderson R.H. Katz Electrical Engineering and Computer Science Department University of California Berkeley Berkeley CA USA Geocast Network Systems Inc. Menlo Park CA USA

Advances in satellite technology are enabling the deployment of large constellations of low Earth Orbiting (LEO) satellites. Next-generation systems will be tailored for broadband, packet-switched services, and therefore require either distributed or centralized packet routing mechanisms. Some researchers have hypothesized that the semi-regular mesh topology of a polar-orbiting constellation admits a simple distributed routing protocol based on using geographic information embedded in the node address. We take a closer look at this hypothesis in the context of commercially-proposed constellation designs. Using simulation, we study a distributed routing protocol that selects the next hop based on a minimization of the remaining distance to the destination. Our numerical results indicate that this routing strategy usually yields good routes, with an average latency degradation of less than 10 ms when compared with the optimal route. However, there are locations in the topology, most notably around the counter-rotating seams, the polar regions, and close to the destination of a packet, where the assumption of a regular mesh topology breaks down and it is difficult to guarantee robustness without adding significant additional complexity to the protocol.

关键词： Low earth orbit satellites Delay Topology Routing protocols Degradation Robustness Satellite constellations Artificial satellites Mobile communication Narrowband

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Bit-error probability analysis of compact antenna arrays with maximal-ratio combining in correlated Nakagami fading

Bit-error probability analysis of compact antenna arrays wit...

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Sensor Array and Multichannel Signal Processing Workshop

作者： Jianxia Luo J. Zeidler S. McLaughlin Department of Electrical & Computer Engineering University of California San Diego La Jolla CA USA Hughes Network Systems Inc. USA SPAWAR Systems Center San Diego USA Department of Electronics & Electrical Engineering University of Edinburgh UK

This paper presents the bit-error probability performance of a compact space diversity receiver for the reception of binary non-coherent and coherent phase-shift-keying (PSK) and frequency shift keying (FSK) signals through a correlated Nakagami (1960) fading channel. Analytical expressions for the average bit-error-rate (BER) are derived as a function of the covariance matrix of the multipath component signals at the antenna elements. Closed-form expressions for the spatial cross-correlation are obtained under a Gaussian angular power profile assumption. This analysis provides a direct means of computing the average BER as a function of the array characteristics and the operating environment for a wide range of multipath fading conditions. The effects of the antenna array spacing, mutual coupling, and the operating environment (the angular spread and mean angle-of-arrival) on the BER performance are illustrated.

关键词： Antenna arrays Bit error rate Phase shift keying Frequency shift keying Fading Signal analysis Covariance matrix Antenna accessories Closed-form solution Mutual coupling

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A Remote Program Execution Mechanism with network Transparency on Multi-Platform Environment

A Remote Program Execution Mechanism with Network Transparen...

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2000 International Seminar on Teletraffic and network

作者： Kazuhiko Kinoshita Masaaki Takase Nariyoshi Yamai Koso Murakami Department of Information Systems Engineering Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan IP Network Systems Laboratory Network Systems Labs. Fujitsu Labs.LTD.4-1-1 Shimo-Odanaka Nakaraha Kawasaki Kanagawa 211-8588 Japan Computer Center Okayama University 3-1-1 Tsushimanaka Okayama Okayama 700-8530 Japan Department of Information Systems Engineering Graduate School of Engineering Osaka University 2-1 Yamadaoka Suita Osaka 565-0871 Japan

In this paper,we present a remote programexecution mechanism with networktransparency which works even on a multi-platform *** network transparencyfacilities,our system supports file sharing,environment preservation and terminal ***,all messages between theirmachines are encrypted for secure ***,we have implemented a prototype systemfor UNIX and *** to thetest runs,we have confirmed the prototypesystem has network transparency actually and itsresponse time is small enough.

关键词： A Remote Program Execution Mechanism with network Transparency on Multi-Platform Environment

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Direct line spectral frequency adaptation in second order cascade sections 33

Direct line spectral frequency adaptation in second order ca...

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33rd Asilomar Conference on Signals, systems, and computers, ACSSC 1999

作者： Beex, A.A. Zakaria, Gaguk Systems Group - DSP Research Laboratory Bradley Department of Electrical and Computer Engineering Virginia TECH BlacksburgVA24061-0111 United States Hughes Network Systems GermantownMD20876 United States

ISBN: (纸本)0780357000

We propose the adaptive cascade recursive least squares with subsection adaptation (CRLS-SA) algorithm for direct estimation of line spectral frequencies (LSF) for use in speech coding. The least squares based CRLS-SA algorithm has a low computational complexity since each section is adapted independently from other sections. Using CRLS-SA, the LSF can be obtained directly from the coefficients of each section of the CRLS-SA structure. Two CRLS-SA approaches can be used for estimating LSF: use CRLS-SA as an AR inverse filter and obtain the LSF by converting the coefficients of each second order filter using a look-up table or, alternatively, construct a cascade of second order LSF polynomials P(z) and Q(z), and adapt each using CRLS-SA. The results show that the LSF estimates from CRLS-SA are competitive with the results obtained by the popular autocorrelation method followed by approximation using Chebyshev polynomials. © 1999 IEEE.

关键词： Polynomials

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Relative convergence of the cascade RLS with subsection adaptation algorithm 33

Relative convergence of the cascade RLS with subsection adap...

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33rd Asilomar Conference on Signals, systems, and computers, ACSSC 1999

作者： Zakaria, G. Beex, A.A. Hughes Network Systems GermantownMD20876 United States Systems Group - DSP Research Laboratory Bradley Department of Electrical and Computer Engineering Virginia TECH BlacksburgVA24061-0111 United States

ISBN: (纸本)0780357000

We analyze the convergence behavior of the CRLS-SA algorithm for inverse filtering. The CRLS-SA is a cascade adaptive filter based on the RLS algorithm, with each section adapted independently based on global minimization. The subsection adaptation results in reduced computational complexity. The rate of convergence is evaluated based on the convergence time constant defined as the ratio of condition number and sensitivity. The smaller the convergence time constant, the faster the structure converges. Analysis and simulation explain and show that CRLS-SA exhibits faster convergence than the direct form RLS adaptive filter for speech type signals. © 1999 IEEE.

关键词： Adaptive filters

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New blind/semi-blind equalization algorithms for GSM systems 2

New blind/semi-blind equalization algorithms for GSM systems

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2nd IEEE Workshop on Signal Processing Advances in Wireless Communications, SPAWC 1999

作者： La, Ge Ding, Zhi 11717 Exploration Lane Hughes Network Systems GermantownMD20876 United States Department of Electrical and Computer Engineering University of Iowa Iowa CityIA52242 United States

ISBN: (纸本)0780355997

We propose a GSM channel identification algorithm based on the decision feedback of the derotation-based constant modulus (DB-CMA) equalizer. By using the entire DB-CMA equalizer output as the reference "training", the channel impulse response can be more accurately identified for sequence estimation. We also propose a new semi-blind channel identification method. Based on the blind subspace method, a shorter training sequence is combined with "reliable" subspace information for channel identification with lower sensitivity to channel order mismatch and robustness to common zeros among diversity subchannels. Both methods are based on an approximated linearization of GMSK modulation and its single-input two-output model resulted from a derotation scheme 121. Overall improvement in the system efficiency is achieved. © 1999 IEEE.

关键词： Impulse response

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Blind linear equalization for GSM signals in a mobile environment 1

Blind linear equalization for GSM signals in a mobile enviro...

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1st IEEE Annual Wireless Communications and networking Conference, WCNC 1999

作者： Li, Ge Ding, Zhi Hughes Network Systems 11717 Exploration Lane GermantownMD20876 United States Department of Electrical and Computer Engineering University of Iowa Iowa CityIA52242 United States

ISBN: (纸本)0780356683

We investigate the application of blind adaptive equalizers in GSM wireless communication systems. Based on a single-input two-output linear approximated model, a diversity based constant modulus algorithm (CMA) and super-exponential algorithm (SEA) adaptive equalizers are implemented to GSM systems without additional antennas. These diversity based CMA and SEA equalizers are robust to channel order mismatch that cannot be overcome by SOS blind channel algorithms. They are also applicable to time-variant mobile channels due to utilization of statistical information from the entire burst. The condition for the adaptive equalizers to converge is given. All simulation results are based on a more practical wireless channel model that is quasi-time-variant (piecewise time-invariant). © 1999 IEEE.

关键词： Global system for mobile communications

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Resource management for fault tolerant path structures in SONET ring networks

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Journal of network and systems Management 1999年第4期7卷 373-394页

作者： Grover, Wayne D. TRLabs Department of Electrical and Computer Engineering University of Alberta Edmonton Alta. Canada TRLabs #800 10611-98 Ave. Edmonton Alta. T5K 2P7 Canada Network Systems TRLabs University of Alberta

There is growing interest on the part of network operators in the ability to analyze the availability of path implementations in their networks and to provide various grades of assured service availability to customers. The calculation of availability is, however, considerably more complex in today's SONET ring-based networks than in prior point-to-point systems. This is due both to the active protection nature of the rings and their dual-redundant interconnect strategies. We show that there is also more than one option for dual-ring interconnection and that a minimum cost high availability path implementation will generally involve a mixture of matched-node and explicitly dual fed treatments. We develop an economic comparison of dual feeding (df) and matched nodes (mn) in terms of the resource consumption of each scheme and show that the choice can be made on an individual ring-by-ring basis with a simple decision criterion. We then develop expressions of general use for the end-to-end unavailability of single-fed, pure df, mn and mixed df-mn path constructions. These results are a step towards on-line provisioning or path planning systems that can minimize the path implementation cost subject to an assured target level of design availability.

关键词： Fiber optic networks

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