最新刊期
卷 28 ， 期 4 ， 2000
- 摘要：This paper investigates the performance of ABR and UBR services in ATM system using traditional TCP congestion control mechanism and the CIPOA.In the ATM network the ER (FB) and EFCI (CCR) algorithms are used.Simulation results show that the TCP performance of ABR service is better than that of UBR service in terms of buffer requirement,fairness of bandwith allocation,throughput,and link utilization.It also comes out that the ER (FB) algorithm outperforms the EFCI (CCR) algorithm and the traditional EFCI algorithm in TCP case when applied for low-complexity network configuration.关键词：TCP/IP;ATM;ABR;UBR0|2|0更新时间：2025-07-02
- 摘要：In this paper,we study the performance of RED (Random Early Detection) algorithm implemented in ATM switches.The throughput,fairness and delay of RED algorithm are studied in the environment of homogeneous and heterogeneous traffic and in the environment of time-varying available bandwidth.It show that RED algorithm,which should be integrated with EPD algorithm,reduces the average queuing delay through effectively controlling the average queue length.Through performance comparison with other packet discard schemes,the ATM switch with RED+EPD algorithm can provide higher throughput,better fairness and smaller delay than the switch with EPD algorithm,so it can support the traffic with delay requirement.关键词：ATM networks;packet discard scheme;Pareto distribution;ON-OFF sources;delay requirement0|2|2更新时间：2025-07-02
- 摘要：SAMA is a new concept to spread spectrum packet radio network and random multiaccess.Seeing that variance of packet length is important to performance of packet network,both analysis and simulation schemes for selection of optimal packet length in SAMA system are presented in this paper based on performance analysis of SAMA.Schemes are generalized for common DS/SSMA packet network easily.关键词：SAMA;spread spectrum communication;packet radio;packet length;optimization methods0|2|2更新时间：2025-07-02
- 摘要：In this paper,we apply Importance Sampling (IS) technique to estimate the BERs of digital fiber-optic communication links.Meanwhile,we use Large Deviations Theory (LDT) technology and select the optimized exponentially twisting (α-Tilted) density of LDT as IS biased density.Experimental results show that this kind of IS simulation method based on LDT has very high efficiency,accuracy and reliability.Especially,it is adapted to estimating very low Bit Error Rates (BERs) of communication links.This method provides an useful tool for researching into Computer-Aided Modeling,Analysis and Design (CAMAD) of digital fiber-optic communication links.关键词：bit error rate estimation;IS;large deviations theory0|2|0更新时间：2025-07-02
- 摘要：In this paper,Hierarchical lapped transforms (HLT) are used to transform the received data signal to the transform domain wherein excision is performed.Unlike the lapped transforms(LT),HLT can effectively isolate the interference energy to a small number of bins in the transform domain by non-uniform division of the signal spectrum.Comparied to the wavelet transforms(WT),HLT have more flexibility in dividing the signal spectrum.Moreover,we have the advantage of low computational complexity while not losing in filtering performance.Simulation results demonstrate that,transform domain excision technique based on HLT is capable of excising stationary narrow-band interference and non-stationary pulsed interference,thus significantly improving the system performance.关键词：HLT;transform domain excision;spread spectrum communications0|2|5更新时间：2025-07-02
- 摘要：In this paper a novel scheduling algorithm called FQLP(Fair Queuing with Loss Priority) is proposed.Theoretical analysis and simulation results show that the allocated bandwidth for real-time services can be guaranteed and a delay bound for real-time services can be provided.Using priority mechanism FQLP increases the network throughput while guaranteeing the QoS of real-time services.关键词：ATM;scheduling algorithm;real-time service;delay0|2|5更新时间：2025-07-02
- 摘要：In telecommunication management network (TMN),Information structures of Managed Objects (MO) in Management Information Base (MIB) are described with Guidelines for the Definition of Managed Objects (GDMO) and Abstract Syntax Notation One (ASN.1).This paper presents a TMN-MIB compiler,e.g.,a method of translating the structures described above into C++ codes.The first step of method is to define the contain class,then is to realize the various types of ASN.1 and templates of GDMO.Consequently,ASN.1 modules and GDMO modules is generated by MIB compiler.The Application Program Interfaces (APIs) of compiler output are also given.关键词：network management;MIB;GDMO;ASN.10|2|1更新时间：2025-07-02
- 摘要：A new flow control scheme considering CCR for ABR service in ATM network is proposed in this paper.The scheme uses a concise algorithm to allocate bandwidth fairly and control the length of switch queue efficiently.Also the scheme works well in the network of more complex configuration.关键词：ABR;flow control;EFCI;FS0|2|1更新时间：2025-07-02
- 摘要：In this paper,we propose a double layer mobile satellite communication system with LEO and MEO satellites to support the multimedia communications and study the VP routing strategy of this double layer system based on ATM technique.From the simulation results,we know that the double layer system can provide excellent performance for multimedia service.关键词：satellite communication;LEO;MEO;multimedia communications;routing1|2|15更新时间：2025-07-02
- 摘要：Self-Healing of SDH mesh network is discussed.Because of slow cross connection time of current DCS,restoration of mesh network cannot accomplish 2 seconds objective completely.Priority restoration is used in order to meet 2s bound for high priority path.Proposed restoration mechanism is composed of two phases:distributed virtual protection switching for high priority path and distributed path self-healing for low priority path.High priority path can be restored within 2s or less and low priority path can be restored by several seconds.In order to realize such restoration mechanism,a multi-route bandwidth allocation method and a message broadcasting method are proposed.These two methods are used in normal conditions.关键词：SDH;self-healing;protection switching;digital cross-connect system0|2|2更新时间：2025-07-02
- 摘要：In this paper a new linear blind adaptive multiuser detector in synchronous DS/CDMA system is proposed.Unlike the commonly used least mean square algorithm,a low computational complexity high order statistics based algorithm using least mean kurtosis (LMK) criterion is adopted.Some changes have been made to the original LMK algorithm in order to realize blind detection in DS/CDMA multiuser detection.Analysis of the blind algorithm is provided.Comparison between the LMS and LMK algorithms is also made via simulations.关键词：CDMA;multiuser detection;LMK criterion0|2|2更新时间：2025-07-02
- 摘要：This paper proposes a novel frequency-shift keying (FSK) demodulation method using the minimum mean squared error (MMSE) criterion.Even though the probability distrbution function of the channel noise is unknown,the structure of the MMSE-based coherent FSK demodulator can be derived.Theoretical analysis and computer simulation results show that the error rate performance of the demodulator is the same as that of the conventional coherent FSK demodulator while the FSK signals are transmitted over an additive white Gaussian noise (AWGN) channel.The former is better than the latter while FSK signals are transmitted over an additive colored Gaussian or non-Gaussian noise channel with imbalance gain in different frequencies.关键词：digital modulation;digital demodulation;optimal detector;digital communications0|2|1更新时间：2025-07-02
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A Method of a Wide-band and Weak Spread Spectrum Signal Demodulation Using Acousto-optic Correlators
摘要：A method of correlative demodulation of a wide-band and weak spread spectrum signal is proposed using an acousto-optic correlator.A mathematical model of the acousto-optic correlator and photodetector is given,then the dynamic range of two kinds of diffraction light detection methods are derived.The effect of the Gaussian distribution of laser amplitude,laser window's function and the acoustic attenuation of medium on correlative peak and the main-peak to side-lobe is obtained by computer simulation and experiments.The principle experiment of acousto-optic correlative demodulation of the spread spectrum signal is done.The results of experiments are basically consistent with the theoretical analysis.The capabilities of the method are demonstrated.关键词：acousto-optic correlators;spread spectrum communication;demodulation;diffraction0|2|0更新时间：2025-07-02 - 摘要：Two-pole filter banks,a novel noncoherent integrator,is proposed as a detector for a scanning radar.Compared with conventional two-pole filter,the proposed integrator is more stable and less sensitive to filter coefficients.In addition,the new integrator has the same computation amount and nearly the same performance as the two-pole filter.Therefore,the two-pole filter banks is robust and practical.关键词：two-pole filter banks;nonncoherent integrator;robustness0|2|2更新时间：2025-07-02
- 摘要：This paper presents a method of using codebook and dynamic interpolation constraint to solve the inverse speech problem.The vocal-tract is modeled by coefficients of band-limited Fourier cosine expansion of logarithm area function,together with a variable vocal-tract length.The lowest N zero frequencies are added to the acoustic target information.By using a root-cell acoustic-to-geometric mapping codebook,the zeros and vocal-tract lengths of the endpoint of vowel-to-vowel transition are determined.Their transitions are then constrained by interpolation method.The result of computer simulation shows effectiveness of the method.关键词：inverse speech solution;speech analysis and synthesis;speech processing0|2|1更新时间：2025-07-02
- 摘要：Where should invisible image watermarks be embedded in DCT domain in order for the image watermarks to be invisible and robust?Though many papers in the literature agree that watermarks should be embedded in perceptually significant components,DC components are explicitly excluded from watermark embedding.In this paper,a new embedding strategy and an algorithm applying the strategy for watermarking in DCT domain is proposed.Based on a quantitative analysis on magnitude of DCT components,we argue that more robustness can be achieved if watermarks are embedded in DC components since DC components have much larger perceptual capacity than any AC components.Applying this embedding strategy,an adaptive watermarking algorithm incorporating the feature of visual masking of human vision system is presented.Experimental results demonstrate that the embedding strategy is effective and the invisible watermarks thus generated are very robust.关键词：image watermarking;embedding strategy;visual masking;DCT;DC components0|2|105更新时间：2025-07-02
- 摘要：The significance of modern embodying information technique,the history and present situation of its developmnt and its wide prospect to practical use are fist introduced.Then we realize a kind of new embodying information technique by using bit-plane embodying information technique in a color image.Compared with other ways of emboding information technique,it has features of being well hidden,capability of resisting jam and making little interference to the embodying information technique.On the base of it,we bring out a way to add watermark to a color image,and the image can be recovered with little change.So it can be a valid way of protecting important images.关键词：embodying information;bit-plane;watermark1|2|9更新时间：2025-07-02
- 摘要：This paper is first focused on the discussion about the constructing method of general integer wavelet transform.Then by means of subblock DPCM and integer wavelet transforms,the encoding compressive method of the near-lossless image compression is obtained for remote sensing images and tested on the experiments.This method is of the following features:(1)the real-time processing of remote sensing images is possible for real-time transmission;(2)hardware implementation is easy;(3)the algorithm is of parallel structure;(4)only addition,subtraction and bit-shift are involved in the processing.Many experiments help illustrate that this method is an effective compressive encoding approach to remote sensing images.关键词：image compression;integer wavelet transform;lift scheme;near-lossless compression;remote sensing image0|2|3更新时间：2025-07-02
- 摘要：A novel method of content-based image segmentation using deformable template matching is proposed.A two-dimensional (2-D) deformable template based on orthogonal curves is built by pre-computing extensions of the deformable template along orthogonal curves and sampling the curves uniformly.Then the definitions of internal and external energy functions are given according to the image segmentation problem,and genetic algorithm is used to obtain globally optimal solutions.The proposed method uses a lower-dimensional search space than conventional methods and reduces the sensitivity of the algorithm to initial placement of the template.Experiments on real-world images and in simulations at low signal-to-noise ratio show the robustness and good performance of the method.关键词：active contours;deformable template;image segmentation;genetic algorithm0|2|4更新时间：2025-07-02
- 摘要：Concept of texture primitive's gray pattern and texture analysis by means of the pattern statistics are presented.We employed texture primitive's pattern histogram to define several histogram features which are served as texture features to classify textures and perform texture segmentation.Comparison experiments of this method to the one by means of Laws texture energy approach show that it can achieve better results than the latter one,and is a promising way of texture analysis.关键词：texture;texture primitive;pattern histogram0|2|13更新时间：2025-07-02
- 摘要：In this paper,we analyzed the Self-Quantization of Subtrees(SQS) in Wavelet-Fractal transform for image coding algorithm of Davis by using the Linear System Theory.We find that the encoding process is done by encoding the parameters of this dynamical system and there is an equivalence of the attractor of a SQS transformation and the steady-state of a dynamical system.From the system point of view.the convergence of a sequence is extensively studied in terms of the stability of its generating system.So,according to some results of the linear control theory,we propose that using the eigenvalues of system provides a more powerful tool for analysis of convergence in attractor decoders.We also give the sufficient-necessary condition of convergence and the sufficient condition of eventually contractive convergence.关键词：fractal;wavelet transform;self-quantization of subtrees;image compression;linear system;stability;eventually contractive convergence0|2|1更新时间：2025-07-02
- 摘要：Weighting exponent m is an important parameter in fuzzy c-means(FCM) algorithm.In this paper,three basic pro-blems are studied in FCM algorithm:the effect of m on the performance of fuzzy clustering,the optimal choice of m,and its preliminary applications in clustering validity.Experimental results indicate that an improper choice of m will influence critically on the performance of clustering,and the optimal range of m is within in the practical applications,which is consistent with the conclusion of Pal.In addition,the approach to determining the optimal number of clusters based on the optimal weighting exponent m* is much effective and sensitive.关键词：weighting exponent;fuzzy clustering;fuzzy c-means algorithm;clustering validity0|2|68更新时间：2025-07-02
- 摘要：The complexity of virtual reality system makes modeling of virtual environment very difficult.In this paper,a object-oriented language model based on attribute-behavior is proposed to give modeling of virtual environment more powerful support,especially make behavior's description and support of system performance more flexible.Then YHVML,a virtual environment modeling language,is designed and implemented,which is platform-independent as the kernel of virtual reality software development platform.关键词：virtual environment;behavior modeling;object oriented modeling0|2|2更新时间：2025-07-02
- 摘要：Employing the extended Halanay's delay differential inequality and Lypunov functions,we study globally exponential stability of equilibrium states of Hopfield neural networks with time-varying delays.The results presented here are independent of any unknown function and are the algebraic oriteria entirely,which are obviously easy to be used.关键词：Halanay's inequality;neural networks;time-varying delay;globally exponential stability1|3|21更新时间：2025-07-02
- 摘要：This paper presents a hardware implementation of programmable of CNN.The main building blocks including cell core circuit,A and B template circuits are designed.Then a CNN and its application in image processing are built and studied.The computer simulation results show that the designed circuits are suitable for CNN implementation because of simple structure,low power dissipation,good frequency property.The modelar design makes it convenient and flexible in image processing.关键词：cellular neural network;analog circuit;programmable template;image processing0|2|0更新时间：2025-07-02
- 摘要：Fractal image coding (FIC) is a new image coding method developed in recent years and has been studied extensively.In the paper,the mathematical principle and the specialties of FIC are introduced,the advances in FIC are presented,meanwhile,the advantages and disadvantages of various schemes are compared.Finally,the shortcomings of current coding scheme,its reasons and the future development of FIC are analyzed.关键词：fractal image coding;image coding;fractal0|2|20更新时间：2025-07-02
- 摘要：Automatic human face recognition is attractive in pattern recognition and image processing.In this paper we gave a survey of automatic human face recognition,mainly aiming at the latest progress.关键词：automatic human face recognition;face detection;face localization1|2|52更新时间：2025-07-02
- 摘要：The Time Division Multiplexing (TDM) is adopted in passive optical network based on Asynchronous Transfer Mode (ATM),so a receiver of the Optical Line Terminal (OLT) operates on the burst mode.A simple method of burst synchronization based on a keyword detection is presented.Simulation and analysis indicate that the configuration is reliable.It can be also used in super PON and other TDMA systems for burst clock recovery with resent commercial ECL circuits.关键词：burst synchronzation;ATM-PON;TDMA0|2|0更新时间：2025-07-02
- 摘要：This paper based on the fact that two topologically-homomorphous (THS) chaotic maps have identical dynamical behaviors.For a class of chaotic maps which are THS to piecewise-linear subjective map,we proposed a method to generate FH sequences with independent and balanced distribution.We also discussed and theoretically analysed and estimated the sequences' balance and maximum Hamming correlation.Finally,we used Chebychev map for our experimental research,the results show that:experiments results are accordant with our theoretic analysis and those sequences have excellent properties.关键词：chaos;piecewise-linear subjective map;topological homomorphism;FH sequence0|2|11更新时间：2025-07-02
- 摘要：Using the LPC-CD,Bark-SD and Mel-CD distortion measures,we experimentally study the Objective Quality Eva-luation of a large number of the speech systems.The result shows that each of these measures gives better correlation between objective and subjective measurement when they are used independently to those systems.Combining their results through a weighted and average way,higher correlation coefficient can be given,we can conclude that these measures have certain validity and utility to appraise the quality of speech systems.关键词：speech system;objective quality evaluation;correlation coefficient0|2|15更新时间：2025-07-02
- 摘要：In this paper,a new key authentication scheme based on the digital signature in Ref.[1] was proposed.At the same time we proposed a new kind of key authentication scheme based on the generalized ElGamal's digital signature.In the new scheme,the certificate is generated independently by the user not via a TC or KAC and Hash function is not applied.关键词：digital signature;key authentication;hash function0|2|1更新时间：2025-07-02
- 摘要：A new method to construct Multitransmitters authentication code by Cartesian authentication code is presented based on Hash function.as a result,many Cartesian authentication codes can be used to construct the systems for threshold generation of authenticators,and also several new constructions for perfect Multitransmitters authentication codes are given.关键词：multitransmitters authentication codes;hash function;authentication code0|2|6更新时间：2025-07-02
- 摘要：The characteristics of the MIM in the TMN are analyzed.According to these characteristics,the RDBMS-based MDBM is presented.The implementation of the MDBM is also given.关键词：TMN;MIM;MDBM1|2|0更新时间：2025-07-02
- 摘要：By constructing bubble wavelet and supper-Gaussian spectrum wavelet,a novel class of wavelet,along with its simple explicit expressions in frequency domain and time domain is presented systematically in this paper.Firstly,the conditions of constructing wavelet used for linear complex analysis of real signal are discussed,and then a new class of wavelet with generalizing linear phase (or Y-wavelet) is introduced.Secondly,the basic performances and features of these new wavelets are studied in both frequency domain and time domain.Based on the proposed wavelet,a number of complex analytic wavelet with different performance and features are obtained by changing a few controlling parametric variables.Some of the existing wavelets is included in this new class of wavelets,or approximated by a specific member of this new class of wavelets.关键词：generalizing linear phase;Y-wavelet;quality factor;oscillation;skew-symmetric0|2|9更新时间：2025-07-02
- 摘要：The convergence of the fuzzy bidirectional associative memories (FBAMs) has been studied in this paper.Some theoretically sufficent and necessary conditions for the convergence of FBAMs and the upper bound of the length of the limit cycles of the FBAMs have been established.It has been proved that,from any starting states,the FBAM(n,m)reaches a related limit cycle in (n-1)2+2 steps.For the FBAM(n,m)constructed by the max-min learning rule,the sequence of the states started by any given associations are nonincreasing and convergent in a number of n+1.关键词：fuzzy bidirectional associative memories;convergence;limit cycles0|2|6更新时间：2025-07-02
- 摘要：At the request of the access code of the CDMA system,the chaotic multilevel digital sequence (CDMS),a new access code,is proposed,which has the advantages of the chaotic analog sequence and the chaotic binary digital sequence.The paper discusses the scheme of generating the sequence,and shows the feasibility and superiority of using it as the access code in the CDMA system.关键词：chaos;chaotic multilevel digital sequence;CDMA;access code0|2|3更新时间：2025-07-02
- 摘要：It is an important topic in EEG research to localize the EEG activity sources from the scalp recordings.In this paper,a new sub-space decomposition algorithm is proposed for the EEG inverse problem,which is based on the delay correlation matrix,and the popular sub-space decomposition algorithm is the special case that the delay is zero.Computer simulation study on a three-layer concentric sphere head model shows its better performance for depressing the spatial coherence noise than the zero-delay popular algorithm.关键词：electroencephalography (EEG);inverse problem;sub-space decomposition0|2|4更新时间：2025-07-02
- 摘要：Transient responses of a MIC Gunn oscillator with a dielectric resonator are simulated by the FDTD algorithm incorporating the nonlinear lumped model of the Gunn diode.关键词：MIC gunn oscillator;dielectric resonator;transient response;FDTD method0|2|6更新时间：2025-07-02
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