最新刊期
卷 29 ， 期 10 ， 2001
- 摘要：A versatile signal model suitable for linear space-time multiuser detectors is proposed.Based on the model,a versatile linear space-time multiuser detector is presented and its optimal solution according to the linear constrained minimum variance (LCMV) criterion is deduced.The analyses of existent linear multiuser detectors demonstrate that these methods are just the special cases of the versatile detector in this paper and can only achieve the suboptimal solution.Hence their interference canceling performance is inferior to the optimal detector in this paper.Finally,numeral simulations are presented.关键词：space-time processing;linear multiuser detector;CDMA2|740|0更新时间：2025-07-16
- 摘要：Recently,multicarrier(MC) transmission schemes have been introduced into CDMA (Code division multiple access) systems to get such advantages as bandwidth efficiency,resistance to multipath fading and high data-rate transmission etc.In this paper,a new model of MC/CDMA system is proposed for forward links transmission.In the proposed systems,the user estimates all subchannels' fading amplitudes and feeds back all indices of its interested subchannels (whose fading amplitude can be accepted) to the basestation,Based on the indices information,we propose a new subchannel allocated method similar to the water-filling (WF) principle.Theoretical and simulation results show that the average performance in the proposed system can be improved compared with that only using the favorite subchannel for each user,given the condition that the random signature sequences are used.关键词：multicarrier CDMA;adaptive subchannel allocation2|665|0更新时间：2025-07-16
- 摘要：The problems of CBR(constant bit rate) traffic in ATM(Asynchronous Transfer Mode) networks are analyzed,and simple methods to calculate the cell loss ratio(CLR) and mean cell delay are derived.It is shown that on the one hand,even if a BW(bandwidth) equal to or larger than the Peak-Cell-Rate(PCR) is allocated for the CBR traffic,a large CLR may result in a small buffer system;on the other hand,with only a comparatively small buffer a very small CLR can be guaranteed when a large number of CBR sources are multiplexed.These results are important for the buffer design,BW allocation and connection admission control in ATM equipment.关键词：broadband integrated service network;asynchronous transfer mode;CBR;queueing2|968|1更新时间：2025-07-16
- 摘要：An adaptive transmission scheme based on PSAM (Pilot Symbol Assisted Modulation) and Adaptive Trellis-Coded M-ary QAM (ATCMQAM) is proposed in this paper.In the following,an analytical model of data capacity in TDMA/FDMA cellular systems is developed for the performance simulation of the scheme.It is shown by simulation result that data capacity of ATCMQAM is 1.8 times that of fixed modulation with 4PSK employed if estimation error is within 3dB and normalized moving distance in a packet period is shorter than 0.4λ with λ being carrier wave length.关键词：data capacity;adaptive transmission;TCM2|837|0更新时间：2025-07-16
- 摘要：Two types of basic reliable multicast transport protocol (ACK based and NAK based) are presented in the paper.Qualitative analysis of these two basic protocols and a modified protocol is given to exhibit their characters in scalability and bandwidth usage on a typical multicast network model.The analysis result shows that the reliable multicast transport protocol based on NAK with NAK Compression scheme consumes less bandwidth and exhibits perfect scalability.关键词：reliable multicast transport protocol;ACK/NAK;NAK compression scheme2|2688|3更新时间：2025-07-16
- 摘要：Network survivability is an important problem for WDM(Wavelength division multiplexing) transport network design.In network architecture using overlay mode,internal dependence of lightpaths could lead to the critical status that the failure of a physical fiber leaves the virtual topology unconnected.This may make the restoration of service by the higher level networks using the WDM network (such as SDH(Synchronous digital hierarchy)),ATM((Asynchronous transfer mode) or IP) impossible.It is necessary to avoid the above cases while embedding virtual topology into physical topology.VTMPD(Virtual topology mapping for protection design) algorithm proposed in this paper aims at Design Protection,considering load balance and capacity constraint of physical links simultaneously.We also compare the performance of VTMPD with the existent DAP(Disjoint alternate path) algorithm.The numerical results show that VTMPD algorithm is better than DAP algorithm.关键词：WDM networks;design protection;taboo search2|832|3更新时间：2025-07-16
- 摘要：Based on the study of Fixed Channel Assignment and Dynamic Channel Assignment,we bring up a new High Efficiency Channel Borrowing Algorithm.It employs the concept of Expected Future Channel Availability Rate to evaluate the effect of channel borrowing on adjacent cells.It includes two channel reallocation procedures to avoid collision.Computer simulation shows that this algorithm has lower Blocking Probability than BDCL(Borrowing with Directional Channel Locking).The Channel Reallocation Ratio is also lower than that of BDCL.关键词：channel assignment;channel borrowing;channel reallocation2|804|0更新时间：2025-07-16
- 摘要：The effects of the channel order and tails on the performance of subspace-based blind signature waveform estimation method in asynchronous DS-CDMA systems are analyzed in theory,and the simulations are carried out.First,we present a signature waveform decomposition model,which means partitioning the signature waveform into the mth-order significant part and the tails,and the corresponding mth-order subspace method is obtained.Secondly,by using matrix perturbation theory,we prove the decomposition validation,which shows that the signature waveform estimation of the mth-order subspace method is close to the mth-order significant part.Finally,from the stable degree of matrix eigenvalue decomposition,the decomposition criterion is derived,which points out that we should avoid modeling the tails and adopt the channel order as small as possible.The simulation results support our theoretical analysis.关键词：DS-CDMA;blind channel estimation;subspace2|632|0更新时间：2025-07-16
- 摘要：The shortcoming of the existing high availability system in network management environment (NMS) is pointed out.New concepts of high availability connectivity and high availability management field in NMS are proposed.Basic concept of software bus is analyzed.The link model,implementation model and network implementation model of software bus are presented.A high availability connectivity software bus based on message mechanism is designed and implemented.This model has been used in National Mobile Network Management System of China successfully.关键词：network management;high availability connectivity;software bus2|839|2更新时间：2025-07-16
- 摘要：A theoretical model of the trash algorithm is established in this paper based on our previous works of simulation study.In this model,all interested parameters of the Trash can be easily derived from given system settings.Simulation shows that this model is a useful practical model in its precision and simplicity.The relations between average queue lengths vs.loss rate of RED (Random early discard),are also studied and solved in this paper.关键词：TCP friendly flow protection;fair queue;RED;buffer management2|981|0更新时间：2025-07-16
- 摘要：The discrete multitone (DMT) modulation/demodulation is the standard transmission technique in the application of asymmetric digital subscriber lines (ADSL).Although the DMT can achieve higher data rate compared with other modulation/demodulation schemes,its computational complexity is too high,especially to compute the modulation/demodulation kernel FFT/IFFT.Hence,a lattice algorithm based on the time-recursive approach is presented,which is very suitable to run in programmable DSP.The algorithm requires only 11% number of multipliers and 9% number of adders compared with the direct implementation(N=256),so it improves greatly ADSL reality and applicability.关键词：DMT(discrete multitone);FFT/IFFT;lattice architecture algorithm2|710|0更新时间：2025-07-16
- 摘要：Information hiding is a new area in the research of information security.It is significantly distinguished from encryption.Subliminal channel existing in some digital signature schemes is a kind of secure channel used for transmitting hidden information.But the information transmitted through this subliminal channel is very limited.Supraliminal channel is a newly presented secure channel used in the case that the receiver and the transmitter share no key ahead of their communication.Supraliminal channel can avoid man-in-the-middle attack.Supraliminal information may be treated as public key for the protection of the subsequent hidden information.Information theoretic analyses are made for the security of the two sorts of information hiding technique.Some security conditions are given.关键词：information hiding;subliminal channel;supraliminal channel;information theory2|867|0更新时间：2025-07-16
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Distillation of Unconditionally-Secure Secret-Key Against Active Adversaries Based on Smooth Entropy
摘要：This paper investigates the distillation of unconditionally-secure secret-key against active adversaries over an insecure and not even authentic channel based on smooth entropy.First we discuss unconditionally secure authentication where the common key is only partially secret,then the authentication method is used to secret-key agreement against active opponents and obtains the size of the secret-key with some probability.关键词：smooth entropy;secret-key agreement;authentication2|975|1更新时间：2025-07-16 - 摘要：The problem of adaptive decoding of space-time trellis code (STTC) on the mobile wireless channels is considered in this paper.After analyzing the maximum likelihood sequence detection (MLSD) of STTC transmission burst with no periodically inserted pilot symbols,we show that per-survivor processing (PSP) can be used to obtain a practical approximated MLSD in this situation.Based on this,a PSP decoder with self-tuning Least-Mean-Square channel tracking is proposed with the advantage that there are only fading rate independent parameters to be pre-determined.Computer simulation results are included to support our development.关键词：PSP;space-time trellis code (STTC);maximum likelihood sequence detection (MLSD)2|743|1更新时间：2025-07-16
- 摘要：The quantification pattern for the MAP decoding algorithm of Turbo codes is studied.The effect of the bound,level and other parameters for quantification are discussed. The good performance of nonuniform quantification is claimed and a reasonable quantificational method is obtained.关键词：Turbo codes;MAP algorithm;quantification;nonuniform quantification2|1738|4更新时间：2025-07-16
- 摘要：A Normal Least Mean Square adaptive filtering algorithm with rotating factor (NLMS-RF) is proposed and its performance and geometry property is analyzed in this paper.Furthermore,it is extend to a multi-channel Affine Projection Algorithm with rotating factor (APA-RF) for stereophonic echo cancellation.The computational complexity of the NLMS-RF is much lower than that of Sankaran's (1999),and the computational complexity of the APA-RF is as much as that of Benesty's (1996).As compared with Benesty's (1996) and Sankaran's (1999),the NLMS-RF and APA-RF is of faster convergence and more accuracy respectively.The simulation in MATLAB indicates its efficiency.关键词：stereo echo cancellation;adaptive algorithm;rotating factor2|893|8更新时间：2025-07-16
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An Improved Flexible Signal Segmentation Algorithm and Automatic Speech Voiced-unvoiced Segmentation
摘要：To the existing problems of the flexible segmentation algorithm proposed by Wang Yongzhong,et al.,in this paper,we make some improvements,and apply the new improved algorithm to automatic speech voiced-unvoiced segmentation.A great deal of numerical simulations and practical data processing show that this new algorithm assuredly solves several problems of the binary-based segment algorithm and the segment algorithm proposed by Wang Yongzhong,and achieves adapted effective segmentation for speech signal.The criterion of distinguishing voiced from unvoiced speech segments proposed by Wesfreid,et al.is adopted,and the new improved algorithm is also applied to automatic speech voiced-unvoiced segmentation.It not only obtains ideal segmentation result,but also there are not much more redundancy segmentations.关键词：segmentation;binary tree;best basis;local cosine transform;speech signal;voiced-unvoiced2|740|1更新时间：2025-07-16 - 摘要：Image quality evaluation is an important field of image processing,but classical image quality evaluation method can not represent knowledge perceived by human eyes.In this paper,we propose that in the case of distorted image processing,the perceptive information of image is increasing while Shannon information is decreased. We define some perceptive parameters,such as the change of texture character,histogram,frequency spectrum,knowledge of image,and we calculate the perceptive information using sigmoid function.The results show that the perceptive information is valid and reasonable.关键词：image quality evaluation;neural;perceptive information3|1660|8更新时间：2025-07-16
- 摘要：In this paper,an new method for progressive image content understanding based on multi-level image description model is proposed,aiming at overcoming the considerable gap between low-level image features and high-level image semantics in the field of image retrieval.In the proposed image content description model,image contents are analyzed and extracted in different levels,reaching at omnidirectional image content description.In addition,the transition from low level to high level is exactly a progressive image understanding.In this paper,a new algorithm for object understanding is proposed,which is based on pre-knowledge and is context-driven,in order to extract image semantics.As a practical instance,discussion about combining the proposed method into content-based image retrieval is also given.关键词：image description model;semantics;object understanding;image retrieval2|947|6更新时间：2025-07-16
- 摘要：The Set Partitioning in Hierarchical Trees (SPIHT) coding method is extended to 3D video coding in this paper.The extended SPIHT (ESPIHT) is proposed.This method creates an embedded compressed bit stream that can be truncated to achieve a desired bit rate or a desired video quality.Furthermore,motion estimation and motion compensation are needless in this method.By theoretical analysis and a lot of simulations,it can be found that ESPIHT is very effective for video sequence coding,but its compression effectiveness is somewhat reduced when the complicated video sequence is coded.关键词：video compression;wavelet transformation;set partitioning in hierarchical trees(SPIHT);3D-SPIHT;embedded compressed bit stream2|1018|4更新时间：2025-07-16
- 摘要：Bit-plane structure coding and predictive coding are both efficient methods in wavelet compression.In this paper,the correlation of wavelet coefficients in all subbands is studied,a new algorithm named Predictive Bit-plane Wavelet coding is proposed,and the choice of the prediction function is studied.Experiment results show that the PBW algorithm is very effective.关键词：prediction;bit-plane;subband2|831|0更新时间：2025-07-16
- 摘要：A new technique is developed for the data fusion of two images.Two spatially registered images with differing spatial resolutions and color content are merged by modifying the spectral intensity component and then reconstructing the fusion image by means of the inverse IHS transform.The intensity component is modified by a best transform curve,which is obtained by evolutionary strategies,and is closer to the intensity component of multispectral image and is closer to the high resolution image in the meantime.Experimental comparisons show that the method proposed in this paper performs better in preserving spatial resolutions and color content than that of traditional IHS transform technique and wavelet transform fusion method.关键词：image fusion;IHS transform;evolutionary strategies2|1113|0更新时间：2025-07-16
- 摘要：A new blind source separation algorithm called DBBSS (Density Based Blind Source Separation) is proposed.Instead of using nonlinear functions,the DBBSS algorithm use nonparametric kernel density estimation to directly estimate the score functions of the signals.The key advantage of the proposed method over many existing blind source separation algorithms is its ability to separate hybrid mixtures that contain both super-Gaussian and sub-Gaussian sources.The DBBSS algorithm is also very simple in implementation.Simulations show good performance of the proposed algorithm.关键词：blind source separation;independent component analysis;probability density estimation2|1187|5更新时间：2025-07-16
- 摘要：Support vector machine is new machine learning technique developped from the middle of 1990s.Being different from traditional neural network,it is based on structure risk minimization principle,while the latter on empirical risk minimization principle.A large number of experiments have shown that,comparing with traditional neural network,support vector machine has not only simpler structure,but also better performances,especially better generalization ability.In this paper,some new developments on support vector machine are introduced so as to draw our attention.关键词：support vector machine;pattern recognition;algorithm3|1587|23更新时间：2025-07-16
- 摘要：Multirate scheme in WCDMA (Wideband Code Division Multiple Access) deals with how to multiplex several services with different rates and Quality of Service (QoS) in a flexible and efficient way,and is a distinct characteristic in the 3G mobile communication systems.Rate Matching Algorithm is the key algorithm in Multirate scheme.This paper,according to the latest WCDMA (FDD) multirate scheme of 3GPP(3G partnership project),presents detailed comparison and analysis of rate matching algorithm in the uplink/downlink,and carries out some preliminary discussion about its possible improvement.关键词：WCDMA;multirate scheme;rate matching2|2236|0更新时间：2025-07-16
- 摘要：In this paper,a new model of channel assignment based on the carrier-to-interference ratio (CIR) of the uplinks in cellular mobile networks is presented.Compared with the classical compatibility matrix model,the new model is more accurate and is adequate for analyzing the interference adaptive channel assignment scheme.For comparison purpose,an improved genetic algorithm developed from the genetic algorithm and Tabu search for solving the channel assignment problem (CAP) is also proposed.Both analysis and simulation show that the new model can describe practical systems more precisely,and can lead to more efficient resource utilization when employed to solve CAP.关键词：combinatorial optimization;optimization model;channel assignment;cellular system;mobile communications2|808|0更新时间：2025-07-16
- 摘要：According to the practical demands of the ATM passive optical network,we analyse the dc-coupled burst mode receiver.The result demonstrates that the burst-mode receiver based on dynamic peak-detector is unable to be applied because of larger network capacity penalty and sensitivity penalty,but the burst-mode receiver based on local peak-detector can meet the network demand.关键词：ATM-PON;burst-mode receiver;TDMA2|905|0更新时间：2025-07-16
- 摘要：A highly effective method based on factorization for designing two-channel perfect reconstruction (PR) filter banks is presented in this paper.First,the PR condition of two-channel filter banks and Euclidean complementary (EC) polynomials are studied.Second,a solution for EC is obtained by constructing a polyphase matrix with a constant determinant based on factorization.Next the design procedures of the method is described.Final some examples are given to illustrate that the method is effective.关键词：factorization;perfect reconstruction;Euclidean algorithm;two-channel filter banks2|1575|2更新时间：2025-07-16
- 摘要：In this paper,the basic principle of LD-CELP (Low-Delay Code Excited Linear Prediction) Algorithm is introduced.Based on a detailed analysis of the vector quantization of the algorithm,an improved scheme is proposed to increase the coding speed of LD-CELP algorithm.It is shown by simulation experiments that with the improved scheme,the coding speed has been doubled,while the SNR has decreased by about 1.2dB which is small enough to guarantee the quality of the coding.关键词：LD-CELP algorithm;vector quantization;speech coding2|915|0更新时间：2025-07-16
- 摘要：Some important performances of multiwavelets are summarized,and pre-processing of several multiwavelets are proposed.An image compression example is given,with satisfactory effects.The results show that the multiwavelet transform of Opt-recl has non-boundary distortion,and can obtains high peak signal-to-noise ratio (PSNR).关键词：multiwavelet;prefilter;balanced multiwavelet;image compression2|1100|6更新时间：2025-07-16
- 摘要：This article puts forward a more efficient arithmetic for image recognition.We combine anti-noise and reduce-dimension performance of Radon transform and multi-resolution analysis of ZC(zero crossing) fingerprint graph and use BT(binary tree) as a tool for ZC fingerprint graph expression.Thus we put forward a distinguish method,and it acquired a better effect in image recognition.关键词：image recognition;Radon transform;ZC fingerprint graph;binary tree2|907|0更新时间：2025-07-16
- 摘要：An improved wavelet watermarking algorithm based on chaotic property is proposed.The random sequence acted as watermark is generated using chaotic function model.Since the chaotic random sequence is sensitive to initial value,different random sequence causes different watermark,which makes digital watermark be unique.Therefore it is impossible for an attacker to forge digital watermark and to detect repudiately.The embedded watermark is robust to compression and noise addition etc.关键词：chaotic property;wavelet transform;digital watermarking;copyright protection2|1136|7更新时间：2025-07-16
- 摘要：In virtue of the actions of a signal upon harmonic oscillator and harmonic oscillator array,the instantaneous energy density spectrum of a signal is defined.Furthermore,definitions of the instantaneous energy,the power density spectrum,the power,the energy density spectrum and the total energy of a signal are introduced.Properties of power density spectrum and the relationships between the power density spectrum and other physical quantities are presented.关键词：signal;instantaneous energy spectrum;power density spectrum;time-frequency analysis2|669|1更新时间：2025-07-16
- 摘要：A one-dimensional iterative chaotic map with infinite collapses which has bigger Lyapunov exponents is proposed.The locations and lengths of its periodic windows shown in bifurcation diagram are analyzed.Ideal chaotic model can be produced by selecting parameter of the map properly.The model proposed also has stronger inner randomicity after testing its even distribution characteristics.关键词：chaotic map with infinite collapses;Lyapunov exponent;periodic windows;test2|1000|0更新时间：2025-07-16
- 摘要：In this paper,the parameters of scattering centers with frequency dependence for 2-D radar target in the colored Gaussian noise are extracted as the high-resolution target feature vectors for ATR.Moreover,the extraction method developed is not restricted by high SNR threshold and Rayleigh resolution limits of radar.Eight stages ATR scheme based on the complex model is also proposed by using hybrid algorithm.Finally,an illustrative example is given.关键词：inverse scattering;radar target modeling;automatic target recognition2|846|2更新时间：2025-07-16
- 摘要：An effective searching algorithm based on a new idea,difference-adjusted,and a fast algorithm for calculating square root are presented to factorize large integer n=pq(p、q are large primes) in some conditions.Consequently,a great deal of weakness existing in the cryptosystem based on the factorization are found and it is very difficult to avoid selecting them in practice.It can be well used in the analysis of the secure in the public key cryptosystem based on the factorization.关键词：factoring;cryptography;RSA2|1313|1更新时间：2025-07-16
- 摘要：For the existing nonstationary spatial characteristics of radio frequency interference (RFI) in high frequency (HF) radar,Fabrizio came up with an interference rejection method.Nevertheless,the method ignored its side effects on the coherent integration of target signals.This effect is analyzed in this paper.On the basis of the analysis a novel array pattern synthesis algorithm is proposed and further applied to the adaptive interference cancellation in HF radar.Simulation results show that the performance of HF radar is greatly improved.关键词：HF radar;interference rejection;array pattern synthesis2|1455|6更新时间：2025-07-16
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