最新刊期
卷 30 ， 期 7 ， 2002
- 摘要：To satisfy requirements of the future communications,framework of a novel wireless communication system based on distribution concept is proposed in this paper.Logical structure of distributed wireless communication system (DWCS) and implementation methods for different layers are described in detail.Analysis shows that DWCS has the characteristics of distribution,system-open,full-coverage,flexibility,scalability and expansibility.关键词：distributed system;wireless communication;software radio2|1909|1更新时间：2025-07-16
- 摘要：In this paper,a method of equalization of OFDM (Orthogonal Frequency Division Multiplexing) signal is described.If the length of its cyclic prefix is larger than the delay spread of transmission channel,we can get a simple frequency equalizer to demodulate OFDM signal.However,the use of cyclic prefix degrades the efficiency of transmission greatly.For this,we give a new equalizing structure,which improves the efficiency of transmission of OFDM system.And this method is examined by computer and good characteristics are confirmed.关键词：OFDM;equalizing;cyclic-prefix;re-construction cancellation2|1203|2更新时间：2025-07-16
- 摘要：This paper describes a novel design method of real time video processing,de-interlacing,color transient improvement and color space conversion,which is suitable for VLSI implementation.A synchronous and parallel pipeline architecture is proposed to reduce the complexity of video processing.The hardware design based on IP module of SOC is also discussed.This design has been verified by Synopsys EDA tool based on 0.35μm CMOS.关键词：synchronous and parallel architecture;video processing;IP module;VLSI architecture2|1028|0更新时间：2025-07-16
- 摘要：In the paper,a new image signature is computed for content-based image retrieval.The signature provides a compact description of all image aspects,including shape,color and texture.Also the signature is invariant to 2D rigid transformation,such as rotation,scaling and translation.By experiment,the retrieval result is satisfactory.关键词：image retrieval;DFT;invarient;log-polar transformation2|1057|2更新时间：2025-07-16
- 摘要：The problem of information hiding and extracting is studied in the perspective of system model in this paper.An approach is proposed to measure the performance of information extracting algorithms by using the estimation theory.The Cramer-Rao Lower Bounds (CRLB) are derived for four algorithms of information extracting and the simulation results are given to corroborate the analysis.关键词：information hiding and extracting;parameter estimation;CRLB2|950|2更新时间：2025-07-16
- 摘要：It is found that the phonetic similarities in the Mandarin digits are the main reasons for the difficulty of Mandarin digit recognition.In this paper,an improved linear discriminant analysis (LDA) based on the states of hidden Markov models (HMM) is presented.The recognition model discriminability is greatly improved by gathering the confusion data to the given states and then using the state-specific discriminative transformation.The experiments show that it increases the recognition rate greatly even if the simple models with insufficient states are used.The recognition accuracy of isolated Mandarin digits is over 99.32% after using optimal linear discriminative transformation.关键词：LDA;Mandarin digit speech recognition;discriminative transformation2|1036|1更新时间：2025-07-16
- 摘要：In Speech Recognition,features from different acoustic units are not independent.The correlation between different acoustic units is called "Spatial Correlation".Spatial Correlation is important for acoustic model estimation.In the paper,we proposed a new method of using spatial information in speech recognition.We use linear equation to subscribe spatial correlation,calculate equation coefficients by K-L transformation,and develop a new training algorithm with the linear constraints.Experimental results show the new method brings significant improvement in error reduction.关键词：speech recognition;acoustic codebook;parameter estimation;spatial correlation;linear constraints2|1005|1更新时间：2025-07-16
- 摘要：We proposed a new speech recognition method by the integration of the VQ,HMM and an unsupervised speaker adaptation algorithm,it comply a VQ-distortion measure at each state instead of a output probability used by a traditional HMM,and uses an fuzzy adaptive VQ algorithm to alter the codewords for speaker adaptation.In this paper,the new combined method is compared with CHMM by the task of speaker-independent Chinese spoken digit (isolated/connected) recognition,and the results confirmed that the good performance of the new method and superior to traditional CHMM.关键词：speech recognition;fuzzy;VQ;HMM;unsupervised speaker adaptation2|980|0更新时间：2025-07-16
- 摘要：This paper proposes a new method for designing orthogonal and biorthogonal M-channel structurally perfect reconstruction (PR) Cosine-Modulated filter banks (CMFB) without constraint.To guarantee condition of CMFB PR and adjust overall input-output delay,the structure based on the lifting scheme is used in proposed method.The new method is superior to existed methods in low design complexity.Finally some examples are given to illustrate the method.关键词：M-channel filter banks;lattice structure;perfect reconstruction2|948|2更新时间：2025-07-16
- 摘要：Macrodiversity is an effective means to overcome large-scale fading effects.Much of previous work focused on its benefits to the reverse link in CDMA systems.However,its effect on the forward link is less well understood.In this paper,we analyze the CDMA forward-link capacity with macrodiversity and the results show that macrodiversity causes forward-link capacity loss whatever power allocation scheme is adopted.Basd on the analysis of the cause of capacity loss,we further present a new transmission scheme,in which some joint control among the involved base stations is made to assure that the signals arrived at the desired mobile in phase and simultaneously.The simulation results show that in the new transmission scheme much higher capacity can be achieved with macrodiversity and the capacity increases rapidly with the number of involved base stations.关键词：CDMA;macrodiversity;forward-link capacity2|895|0更新时间：2025-07-16
- 摘要：To suppress the interference and improve capacity of multi-carrier CDMA (MC-CDMA),a new method of joint detection and decoding is proposed in this paper.Also,a new feedback concatenate structure is obtained.Current researches on the performance of the MC-CDMA detectors made the assumption that the multiplicative complex channel coefficients are perfectly known in the receiver,which is impractical in the engineering.In this paper,channel is firstly estimated with the aid of pilot symbol.It is then optimized by feedback decoding data.With the scheme,channel can be estimated precisely without long pilot symbols.Simulation results show that the performance of joint detection and decoding is much better than traditional concatenated structure.Thus,our proposed scheme is an optimal detection method.关键词：MC-CDMA;Turbo code;joint detection;MMSE2|926|0更新时间：2025-07-16
- 摘要：In this paper,We first present four data-selected schemes based on chip-matched filter for the multiuser receiver in multipath CDMA channels,and study the impact of these schemes on multiple-access interference (MAI) and inter-symbol interference (ISI).Then,we present the least mean-square (LMS) blind space-time multiuser detection method based on the Rosen's gradient projection,and analyze the effect of these schemes on the computational complexity of the presented detection method.Finally,we provide a reasonable and realizable method by analyzing the results of the simulations,and this method has the advantages of lowering the computational complexity,therefore it is interesting for application.关键词：LMS;space-time processing;blind multiuser detection;direct-sequence CDMA (DS/CDMA)2|770|0更新时间：2025-07-16
- 摘要：In the updated WCDMA proposal,the transmit diversity schemes can be classified as open loop mode and closed loop mode.This paper presents the performances of these two schemes based on WCDMA system.Analytic and simulation results show that the closed loop mode outperforms the open loop mode at pedestrian speeds,while the open loop mode performs better than the closed loop mode at vehicular speeds.关键词：WCDMA;transmit diversity;closed-loop;space-time encoding2|978|2更新时间：2025-07-16
- 摘要：In this paper,we propose an analytical model for the dropping behavior at the network bottleneck where large number of TCP (Transmission controd protocol) connections exist.The inevitable congestion and buffer overflow at the bottleneck is the main reason of the packet loss in networks,which has great influence on the network performance.This model predicts the packet loss rate and transmission interruption rate of the sustained TCP connections sharing the bottleneck link.If most packet-losses are caused by network congestion,our models can give close approximations to the real networks that always contain many connections.The analytical model is useful in studying the effects of TCP,finding new effective algorithm of congestion control,and determining how TCP needs to be modified in the long term for efficient operation over emerging networks.关键词：multiple TCP connections;congestion control;packet-dropping model2|1834|0更新时间：2025-07-16
- 摘要：Anonymous routing connections on open computer networks are strongly resistant to both eavesdropping and traffic analysis,as any user of the anonymous networks can only obtain the addresses of its predecessor and successor sites.The anonymous routing schemes available are constructed either by using atomic signature and encryption or by nested signature and encryption,or onion routing.A new scheme that hides information and prevents from disturbing data packages is presented with Domain-Verifiable Signcryption technique.In this context,it appears to be efficient that the system is built by using efficient digital signcryption techniques instead of traditional paradigm of generating a digital signature of a message and then encrypting the signature together with the message and reducing computation and overhead costs in the protocol.At the same time,the merit of two kinds of schemes above is obtained.Finally,an analysis of security is given.关键词：networks security;information hiding;anonymous routing;signcryption;domain-verifiable signcryption2|899|0更新时间：2025-07-16
- 摘要：This paper presents Rice-K model which is statistical for a land mobile satellite link in non-urban areas.This model assumes that the slow changes on the received signal envelope are K-dsitributed due to the shadowing and the multi-path fading including the line of sight path component is Rician distributed.On this basis,the expressions of cumulative density probability function (c.d.f) and the bit error probability of the received signal envelope are derived.Furthermore,the parameters of Rice-K model are estimated by means of moment method in which sample moments and normalised sample moments are used.Also,performance of this kind of parameter estimation is studied.Finally,Rice-K model is validated through the comparison between measured data and the analytical curve given by Rice-K model.关键词：Rice-K model;K-distribution;normalized moments1|848|0更新时间：2025-07-16
- 摘要：This paper presents the scheme of digital communication using a chaotic carrier.In the transmitter,the bits are mapped to sample functions of chaotic signals emanated from one or more chaotic attractors by modulating phase of excitation term of driven Chua's circuit.The bits are demodulated by the optimal demodulator that consists of synchronizable chaotic circuits in the correlation receiver.The proposed scheme can be used for transmitting binary signal and be extended for M-ary signal.Finally,the numerical simulation results demonstrate the proposed scheme effectiveness.关键词：chaos shift keying;optimal demodulation;phase modulation;driven chua's circuit4|1009|3更新时间：2025-07-16
- 摘要：In this article,a practical 10GHz frame-clock extraction technology based on unequal coding scheme and high Q value filter is introduced and analyzed.We illustrate its basic principle and propose the theoretical models to simulate the effects of parameters of OTDM (Optical Time Division Multiplexing) signals and high Q value filter.Also,we employ this technology in our practical 40Gbit/s OTDM system,and acquire a series of curves and results related to this unit.Finally,the theoretical and experimental results are compared and discussed.关键词：optical time division multiplexing;clock extraction technology;unequal coding scheme2|812|0更新时间：2025-07-16
- 摘要：Because of its predominant capability,TIN (triangulated irregular network) has been widely used in the simplification of terrains represented as height field.During the generation of TIN,selection of input points is the key to the approximation quality of simplified terrains.Usually,the input point is selected according to the importance measure on each point,so research on the calculation of importance measures has attained more and more attention.Based on analysis and comparison of traditional importance measures,we put forward a new importance measure based on local entropy.The results demonstrate that the local entropy criterion has a better performance than any traditional method.In addition,it can effectively conquer the "short sight" problem in previous methods.关键词：height field;terrain simplification;triangulated irregular network (TIN);importance measures;local entropy2|948|2更新时间：2025-07-16
- 摘要：In this paper,the common grounds and differences between E.Oja's idea of statistical principal components analysis in recursion network and S.Kung's adaptive principal components extraction (APEX) algorithm in feature extraction are pointed out.The convergence of the algorithm is proved.Simulation results demonstrate the convergence and stability of the algorithm.It is analyzed that principal components number,subimage size and learning rate have effect on the algorithm.Therefore,it is expressed that the algorithm is a valid feature extraction method with less operation in face recognition.关键词：neural networks;Image Feature Extraction;Principal Components Analysis;APEX Algorithm2|1006|6更新时间：2025-07-16
- 摘要：In order to integrate multiple decisions resulted from different but correlated criteria,a decision making mechanism based on the urn model is proposed in this paper.Applying this mechanism in image segmentation,we can decide not only thresholds of these correlated features independently but also complete segmentation and smoothing within a single process.Experiments show that the proposed mechanism is promising.关键词：decision making;image segmentation;Urn model1|948|4更新时间：2025-07-16
- 摘要：A new K-Winners-Take-All neural network:High-Speed-Winners-Take-All(HS-K-WTA) is presented.HS-K-WTA can identify the k larger elements( or k smaller ones) in a data set.The analysis results about HS-k-WTA algorithm and its complexity are given.The results show that the speed,the hardware realization,and the stability of HS-K-WTA are much better than Winstrons,especially for a lot of atoms of a data set.2|952|1更新时间：2025-07-16
- 摘要：The robust adaptive filtering is researched when the input and output signal are both corrupted by noise in this paper.On the basis of minimizing total mean square error (TMSE) and the steepest descent principle,by modifying the gradient of TMSE,a robust total least mean square (RTLMS) adaptive filter algorithm is proposed.The performance analysis compared with other algorithm demonstrates the proposed algorithm can efficiently reduce the sensitivity of the weight adjusting-tap to noise.The simulation results have also shown that the robust anti-noise performance and the stable convergence precision of the proposed algorithm are remarkably higher than other congener algorithms.And it can still keep nice convergence when a larger learning factor is used and the noise is strong.关键词：adaptive filter;total mean square error;total least mean square;modifying gradient2|924|3更新时间：2025-07-16
- 摘要：A relaxation segmentation algorithm of forward-looking infrared (FLIR) images with edge constraint is presented.An evaluation criterion based on distinct edge pixels is used to examine the segmentation results by the relaxation segmentation algorithm under different initial assignment of probabilities.Thus the good segmentation result can be achieved by automatically adapting initial assignment of probabilities to reach the optimal or suboptimal solution of the evaluation criterion.Experimental results with real FLIR images are given.关键词：image segmentation;FLIR image;relaxation technique;edge constraint2|965|7更新时间：2025-07-16
- 摘要：This paper rewrites least square criterion J(n)= ∑ n i=1 λn-i|e(i)|2,one of the optimal criteria of adaptive filtering algorithm,into matrix form,and proposes a new adaptive filtering algorithm by using recursion of generalized inverse matrix to input signal matrix instead of self-correlation matrix.Computer simulation results show this algorithm performance is better than those of other algorithms such as LMS algorithm、NLMS algorithm、FRLS algorithm、APA algorithm、Leaky-LMS algorithm and RLS algorithm.关键词：adaptive filtering algorithm;least square criterion;recursion of generalized inverse matrix2|1194|7更新时间：2025-07-16
- 摘要：Resilient function is a natural generalization of correlation immunity Boolean function.This paper discusses balanced resilient functions,with following results:a kind of structure of balanced resilient functions is presented,and therefore a method is given which constructs balanced (n+1,m,2t+1) resilient functions from balanced (n,m,2t) resilient functions;a proposition is given and proved that the resilient order of the balanced linear function equals the mini-weight of corresponding block code minus one,and the supremum of this order can often be reached by non-linear functions.关键词：information leakage;Boolean function;correlation immunity;resilient function2|931|0更新时间：2025-07-16
- 摘要：In cellular mobile communications system,the performance of location management scheme has great influence on the service quality of system.This paper proposes a state-based dynamic location management scheme.In which,the location area size is decided according to the user's movement state.Experimenal result shows its performance is much better than the conventional scheme,near to the schemes based on user's characters.Besides,it needs not to change the current location update procedure and paging procedure,and has not any signaling cost adding.It has a great prospect of engineering application.关键词：mobile communications;mobility management;location management2|870|0更新时间：2025-07-16
- 摘要：The Extended self-similar model(ESS)is a general fractional Brownian motion(fBm) model.Its multiscale Hurst parameters have relations with roughness.In the meantime,it doesn't require the roughness to be scale-invariant as fractal dimensions do.The multiscale Hurst parameters can discriminate a large number of natural textures and are suitable to be used for texture classification.Its structure function is based on the difference of the gray levels at some scale.This can be defined by the difference of the lower subband signal.Because wavelet transform has the ability of reducing the noise,the derived features performed better.Our experiments show that higher rate of correct classification to SPOT image is obtained.In the meantime it shows that the texture's self-similarity is more evident in lower subband than that in gray level.关键词：Hurst parameter;wavelet transform;feature extraction;texture classification2|1188|3更新时间：2025-07-16
- 摘要：This paper focuses on the influence of soft decision decoding on multilevel coding (MLC) schemes with different mapping strategies over Rayleigh fading channels.Based on Capacity Rule,8ASK MLC systems are constructed using punctured convolutional codes.The formulations for computing the soft decision metrics with Channel State Information (CSI) are presented for multistage decoding (MSD) and the performance comparisons are made for soft- and hard-decision.The error propagation resulted from the lower level is also discussed.The results can present some references for the optimal design of MLC in fading channels.关键词：soft-decision Viterbi decoding;MLC(Multi-level Coding);MSD(Multi-stage Decoding);mapping;fading channels2|809|0更新时间：2025-07-16
- 摘要：Turbo Interleaver has lacked systemic designing theory and explicit optimum criterion all the time.In this paper,the theory fundament will be discussed, and a multi-grade Math Model is to be founded from two aspects,code-weight analysis and correlativity analysis,in the meanwhile, optimum criterion of mono-interleaver—function S6 is put forward.On the above basis,a novel weight-reverse interleaver is designed for the third-generation mobile communication system ,IMT2000,and computer simulation shows that its performance is excellent,both theory analysis and experiment simulation prove that it is much superior to mother-interleaver that is widely exploited at present in 3GPP standard (3G TS 25.212 V3.3.0).关键词：Turbo code;weight-reverse interleaver2|1092|2更新时间：2025-07-16
- 摘要：This paper analyzes the system capacity of the cdma2000 and then provides a conclusion about the relationship between the data ratio adjustment and the system capacity.For the first time,introduce the service time into the system capacity.Consider the integrated influence of the data ratio and the service time and propose the evidence and scope of the ratio adjustment.The proposed conclusion proves that the system capacity is not always increased with the decrease of the data ratio.Thus it correct the error of the conventional notions.The simulation results show that selecting the data ratio based on the theoretic conclusions could minimize the Outage probability and then get the maximum system capacity.关键词：ratio adjustment;CDMA2000;system capacity;service time2|725|0更新时间：2025-07-16
- 摘要：By studying the problems of localizing magnetic target based on single motion scalar magnetometer and based on two motion scalar magnetometers in detail,the authors indicate that magnetic target's position parameters can not be completely ensured by adopting single motion scalar magnetometer ,and present a universal method of localizing magnetic target.The method first searches position parameters in the rough by adopting modified evolution strategy and then finds precision parameters by using simplex method.Testing experiment results indicate the effectivity and large localization area of the method.Since the method need not know magnetic moment in advance,it is practical.In addition,the method can be directly applied to solve the problem of localizing magnetic target based on vector magnetometer after a few modifications.关键词：magnetic target;localizing;nonlinear programming2|1324|10更新时间：2025-07-16
- 摘要：Due to the uncertainty of the application circumstance,it is difficult to describe the noise statistics of integrated navigation system accurately.This may cause the general Kalman filter unstability and even divergence.The common solving method is to estimate covariance matrix Q and R directly by adaptive filter.But the problem is that the increase of equations will cause heavy calculation,thus real-time cannot be ensured.This paper presents a new method to estimate states by ARMA model adaptive parameters identification to solve gain K,at the same time research an anti-saturation algorithm for the error covariance.Computer simulation was carried out according to the analysis and design of the INS/GPS integrated navigation covariance.Computer simulation was carried out according to the analysis and design of the INS/GPS integrated navigation system based on information fusion,and the results show this method is very useful for improving the accuracy and calculation speed of the system.关键词：Information fusion;integrated navigation;adaptive filter;alterable gain;anti-saturation2|1102|3更新时间：2025-07-16
- 摘要：With the rapid increasing of image data,an effective and efficient image retrieval system is needed for finding useful images in large databases or on Internet.Because of the complexity of images,the traditional information retrieval techniques,which are based on value and/or text comparison,are not sufficient.Then the research is shifted to the techniques of content-based image retrieval (CBIR).In this paper,some key issues on CBIR are discussed:image features extraction,similarity measures,the expression of query conditions,retrieval techniques in compressed-domain,the performance evaluation,and so on.Some future research directions are also given in the conclusion.关键词：content-based image retrieval;query by example(QBE);image retrieval in compressed-domain;multimedia techniques5|4994|27更新时间：2025-07-16
- 摘要：Protection Switching Time (PST) is an important metric on evaluating the performances of protection methods in mesh WDM network.This paper provides three types of arithmetic model of PST for dedicated-path protection,shared-path protection and shared-link protection separately.And then some optimal strategies and available solutions are provided on the base of analyzing several principal issues affecting PST.Result of this paper has some reference value for correctly choosing protection method.关键词：wavelength division multiplexing;mesh network;survivability;network protection and restoration;protection switching time2|1118|0更新时间：2025-07-16
- 摘要：Video object segmentation is the key issue in the MPEG-4 International Standard.This paper presents a new method for MPEG-4 video object segmentation from complicated scenes.In this method, the method of template matching and the object tracking method based on the motion estimation and compensation are combined.After the segmentation mask of the current frame has been generated by the motion estimation and compensation,the object colors in the initial frame are the same as the template and the object is detected in the object boundary area by template matching.So the object contour is refined.This object tracking method is able to solve the problems of occlusion and complicated scenes efficiently to certain extent and also tracks objects from an initial frame over any long time.3|986|3更新时间：2025-07-16
- 摘要：Fracatal image coding which can emplog parameters of the dynamic processes of iteration to represent the static image data and break through the theoretical bound of entropy coding has now received wide attention.In this paper,the fractal image coding is employed to compress the multispectral remote sensing images.Making use of the properties of the multispectral remote sensing images,some improvememts are made to the fast fractal image coding method based on the quadtree partitioning.The compression ratio and the coding speed were both improved by sharing the same quadtree partitioning of the range blocks with other different image bands and,in the same time,reducing the size of the searching and matching space of the affine transform by utilizing the spectral correlation of the multispectral remote sensing images.The experimental results show that the performance of the fast fractal coding method based on quadtree partitioning was significantly improved by incorporating our scheme.Satisfactory experimental results are obtained.2|981|2更新时间：2025-07-16
- 摘要：In this paper,we reviewed the art of e-cash in brief,and improved the Brands' e-cash system based on the restrictive blind signature.In our new e-cash system,the withdrawal date and expiry date,prescribed by the bank are embedded in the withdrawn e-cash.Users cannot alter these information later,the bank only needs to keep all used and undue e-cash in his database to trace the double-spender.Thus it reduces the storage level and improves the querying efficiency of the bank to detect double-spending.关键词：blind signature;restrictive blind signature;signature of proof of knowledge2|1458|5更新时间：2025-07-16
- 摘要：First,with a counterexample we point out in this paper an error in HU's method for calculating the core of an information system in the context of rough set based on the discernibility matrix defined therein.Then,we present a new discernibility matrix definition together with a method for the computation of the core and prove the correctness of the method.关键词：rough set;discernibility matrix;core2|1588|157更新时间：2025-07-16
- 摘要：The stability of Hopfield neural network is the foundation of the network's applications.The stability of asymmetric discrete Hopfield neural network is mainly studied and some new simple stability conditions are given in serial,parallel and partially parallel updating mode.The obtained results generalize some existing results.关键词：discrete Hopfield neural networks;stability;energy function2|1743|5更新时间：2025-07-16
- 摘要：A new admission control algorithm for the virtual clock packet scheduling algorithm is proposed in this paper.The existing admission control scheme of the virtual clock algorithm does not consider the circumstances when sessions are set up and torn down.This may worsen packet delay property.Based on the reference model of virtual clock algorithm,the new algorithm prescribe the condition when the bandwidth can be released and allocated.Theoretical and simulation results show this algorithm can fully guarantee the delay property of virtual clock algorithm.The idea of this algorithm can also be applied to other admission control scheme of packet scheduling algorithm.关键词：admission control algorithm;packet scheduling algorithm;delay2|719|0更新时间：2025-07-16
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