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Improved channel estimation method for TD-SCDMA systems

Hunan Daxue Xuebao/Journal of Hunan University Natural Sciences 2008年第3期35卷 72-75页

作者： Luo, Zhi-Nian Zhang, Wen-Jun Li, Ren-Fa College of Computer and Communication Hunan Univ. Changsha 410082 China Institute of Image Communication and Information Processing Department of Electronic Engineering Shanghai Jiaotong Univ. Shanghai 200240 China

An improved channel estimation method based on the Steiner low cost channel estimator was presented, which was used in TD-SCDMA (Time Division-Synchronous Code Division Multiple Access) cellular mobile radio systems. As additive noise has great effect on its performance for Steiner channel estimator, the proposed method employs the time correlated post processing with a threshold filter to reduce channel noise and compensate the channel variation. Simulation has shown that the system performance is considerably improved, which can obtain a performance enhancement of 2 dB even in the high speed vehicle circumstance.

关键词： Mobile radio systems

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SVM based ASM for facial landmarks location

SVM based ASM for facial landmarks location

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8th IEEE International Conference on computer and Information Technology (CIT 2008), vol.1

作者： Chunhua Du Qiang Wu Jie Yang Zheng Wu Institute of Image Processing and Pattern Recognition Shanghai Jiaotong University Shanghai China Department of Computer Systems University of Technology Sydney Australia

Finding a new position for each landmark is a crucial step in active shape model (ASM). Mahalanobis distance minimization is used for this finding, provided there are enough training data such that the grey-level profiles for each landmark follow a multivariate Gaussian distribution. However, this condition could not be satisfied in most cases. In this paper, a new method support vector machine (SVM) based ASM (SVMBASM) is proposed. It approaches the finding task as a small sample size classification problem, and uses SVM classifier to deal with this problem. Moreover, considering imbalanced dataset which contains more negative instances (incorrect candidates for new position) than positive instances (correct candidates for new position), a multi-class classification framework is adopted. Performance evaluation on SJTU face database show that the proposed SVMBASM outperforms the original ASM in terms of the average error as well as the average frequency of convergence.

关键词： Active shape model (ASM) Support vector machine (SVM) Multi-class classification Facial landmark New position

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Local Quaternionic Gabor Binary Patterns for color face recognition

Local Quaternionic Gabor Binary Patterns for color face reco...

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International Conference on Acoustics, Speech, and Signal processing (ICASSP)

作者： Wei Lu Yi Xu Xiaokang Yang Li Song Institute of Image Communication and Information Processing Department of Electronic Engineering Shanghai Jiaotong University Shanghai China Institute for Computer Science University of Freiburg Germany

In this paper, a novel color face recognition method is proposed based on local binary patterns (LBP) of quaternionic Gabor features (QGF). By introducing quaternion Gabor analysis into image representation, we make full use of the interrelationship among different color channels to enhance the performance of the face recognition system. Moreover, the QGF are used to encode the positions and attributes of the face elements. Non-parametric transformation is then imposed on these QGF using LBP method to obtain the robustness against variations of pose, illumination and facial expressions. Compared with the monochromatic face recognition systems, which nowadays dominate the marketplace and research field, this approach materializes the strong potential use of color face recognition system by establishing invariant quaternion wavelet features of color images. The experimental results on the open face database testify the validity of the proposed method under severe noise corruption and distinct variations of scale, illumination and facial expressions.

关键词： Face recognition Quaternions image color analysis Lighting image analysis Performance analysis image representation Robustness Colored noise image databases

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Automatic defogging method for image based on the physical model

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Yi Qi Yi Biao Xue Bao/Chinese Journal of Scientific Instrument 2008年第SUPPL. 2期29卷 371-375页

作者： Zhang, Xiuqiong Gao, Zhisheng Yuan, Hongzhao Institute of Image and Graph College of Computer Science Sichuan University Chengdu 610064 China Department of Computer Science Leshan Teacher's College Leshan 614004 China School of Mathematics and Computer Engineering Xihua University Chengdu 610039 China

An automatic defogging method based on the dichromatic atmospheric scattering model is presented in this paper to avoid the inconvenience by using interactive method. At first, the vanishing point is detected automatically using the Hough transform. The pixel value at the vanishing point is a threshold to segment the sky region. The final defogged image is obtained by using the depth heuristics. The result of many experiments shows that this method prior to the histogram equalization and multi-scale Retinex in the restraining noise and producing good color rendition.

关键词： Hough transforms

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Introducing an incremental learning method for fuzzy descriptor models to identify nonlinear singular systems

Introducing an incremental learning method for fuzzy descrip...

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2008 Mediterranean Conference on Control and Automation, MED'08

作者： Mirmomeni, M. Lucas, C. Shafiee, M. Araabi, B.N. Control and Intelligent Processing Center of Excellence School of Electrical and Computer Eng. University of Tehran Tehran Iran Electrical Engineering Department Amirkabir University of Technology Tehran Iran School of Cognitive Sciences Institute for Studeils in Theoretical Physice and Mathematics Tehran Iran

ISBN: (纸本)9781424425051

Singular systems have been the subject of interest over the last two decades due to their many practical applications. But it has to be said that system identification of such system is still a challenging area because of the difficulty of identification of such systems for their complex structures. In addition, it seems that by developing a useful method for identification of singular system, one can use the useful property of such systems in describing the natural complex phenomena. This paper presents a novel methodology for identifying nonlinear singular systems from empirical data. Singular systems are idealized models for systems with slow and quick modes of change. However, their identification is a challenging problem even for the linear case. A new learning method, generalized locally linear model tree (GLoLiMoT) algorithm is introduced. The contribution of this paper is to provide a method for adjusting the parameters of fuzzy descriptor model, e.g. the splitting ratio and the standard deviation, the number of locally linear neurons or the number of linear singular systems for the consequent part in fuzzy descriptor model as well as the order of the singular system. By these modifications an accurate model of nonlinear singular system is obtained which is compared with several other methods in two case studies. Results depict the power of the proposed approach in describing nonlinear complex phenomena. © 2008 IEEE.

关键词： Trees (mathematics)

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Space-Time-Frequency Characterization of Non-Isotropic MIMO Mobile-to-Mobile Multicarrier Ricean Fading Channels

Space-Time-Frequency Characterization of Non-Isotropic MIMO ...

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International Wireless Communications and Mobile Computing Conference, IWCMC

作者： Xiang Cheng Cheng-Xiang Wang David I. Laurenson Hsiao-Hwa Chen Athanasios V. Vasilakos Joint Research Institute of Signal and Image Processing Heriot-Watt University Edinburgh UK Joint Research Institute of Signal and Image Processing University of Edinburgh Edinburgh UK Department of Engineering Science National Cheng Kung University Tainan Taiwan Department of Computer and Telecommunications Engineering University of Western Macedonia Koza-gun Greece

ISBN: (纸本)9781424422012

This paper proposes a new space-time-frequency (STF) correlation model based on the two-ring model with both single- and double-bounced rays for miltiple-input multiple- output (MIMO) mobile-to-mobile (M2M) multicarrier ricean fading channels in a non-isotropic scattering environment. The proposed model allows us to study the correlation functions (CFs) between any two sub-channels with different carrier frequencies of MIMO M2M Ricean fading channels. The derived STF CF and the corresponding space-Doppler-frequency (SDF) power spectral density (PSD) have generic closed-form expressions including many existing CFs and PSDs as special cases. Based on the derived SDF PSD, the resulting doppler PSD is investigated in more detail in terms of some important parameters. Our numerical evaluations show the impacts of different parameters of the propagation environment on the doppler PSD. More importantly, we find that the shapes of the Doppler PSD are completely different according to single- or double-bounced rays for M2M channels, while they are exactly the same for fixed- to-mobile (F2M) channels. Finally, it is worth mentioning that some interesting observations obtained from these numerical results can be considered as the guidance for further proposing more realistic M2M channel models and building up future measurement campaigns.

关键词： MIMO Scattering Fading Doppler effect Antennas Correlation OFDM

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A Generic Geometrical-Based MIMO Mobile-to-Mobile Channel Model

A Generic Geometrical-Based MIMO Mobile-to-Mobile Channel Mo...

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International Wireless Communications and Mobile Computing Conference, IWCMC

ISBN: (纸本)9781424422012

In this paper, a generic and adaptive geometrical- based stochastic reference model is proposed for multiple-input multiple-output (MIMO) mobile-to-mobile (M2M) Ricean fading channels. The proposed model employs a combined two-ring model and elliptical-ring model, where the received signal is constructed as a sum of the line-of-sight (LoS), single-, and double-bounced rays with different energies. This makes the model sufficiently generic and therefore includes many existing channel models as special cases. Importantly, the model can easily be adapted to a variety of M2M propagation environments, e.g., outdoor macro-, micro, and pico-cells taking into account different vehicle traffic densities, by adjusting model parameters. From the proposed model, the space-time (ST) correlation function (CF) and the corresponding space-Doppler (SD) power spectral density (PSD) of any two sub-channels are derived for a two-dimensional (2D) non-isotropic scattering environment. Finally, some numerical results are presented and compared with measured results. The close agreement between the theoretical and empirical curves verifies the utility of the proposed model.

关键词： Adaptation model MIMO Numerical models Fading Computational modeling Vehicles Antennas

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Using neurofuzzy models and spectral analysis for prediction of the exotic phenomena with catastrophic jumps

Using neurofuzzy models and spectral analysis for prediction...

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International Conference on Computational Science and Its Applications, ICCSA 2008

作者： Mirmomeni, Masoud Lucas, Caro Araabi, Babak Nadjar Control and Intelligent Processing Center of Excellence Electrical and Computer Eng. Department University of Tehran Tehran Iran National Foundations of Elite Tehran Iran Young Researches Club Azad University Tehran Iran School of Cognitive Sciences Institute for Studies in Theoretical Physics and Mathematics Tehran Iran

ISBN: (纸本)3540698388

Catastrophe theory is a mathematical technique for the analysis of system equations, defining the jump phenomena and sudden changes caused by smoothed alterations in the situation. This theory has been used several times to describe many exotic phenomena in different domain of science such as biology and physics. On the other hand, recent technological progress entails high risk levels. Such progress in 21st century has made human life increasingly dependent on technologies which exotic phenomena with catastrophic behaviors seem to be a threat for them. It is meaningful to develop a long-term predictor for modern technologies to avoid such exotic phenomena. In this study, a long-term predictor based on neurofuzzy models and spectral analysis as a powerful method to describe complex phenomena is proposed as an alarm system to avoid unexpected catastrophic events. Results depict the power of this alarm system to protect technologies from undesirable sudden and catastrophic changes. © 2008 Springer-Verlag Berlin Heidelberg.

关键词： Spectrum analysis

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Extraction of complex wavelet features for iris recognition

Extraction of complex wavelet features for iris recognition

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International Conference on Pattern Recognition

作者： Xiaofu He Pengfei Shi Department of Computer Science and Technology East China Jiao Tong University Shanghai China Institute of Image Processing and Pattern Recognition Shandong Jiaotong University Shanghai China

ISBN: (纸本)9781424421749

This paper presents a new feature extraction method for iris recognition. Since two dimensional complex wavelet transform (2D-CWT) does not only keep wavelet transformpsilas properties of multiresolution decomposition analysis and perfect reconstruction, but also adds its new merits: approximate shift invariance, good directional selectivity for 2-D image, and limited redundancy, which are useful for iris feature extraction. So, a set of high frequency 2D-CWT coefficients are selected as features for iris recognition. The phase information of the coefficients is used for feature encoding and Hamming distance is adopted for classification. Experimental results show that the proposed algorithm can get good recognition rate.

关键词： Iris recognition Feature extraction Wavelet analysis Wavelet transforms image resolution image analysis image reconstruction Two dimensional displays Frequency Encoding

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An Improved Landweber Method for Restoration of Aero-Optically Degraded images

An Improved Landweber Method for Restoration of Aero-Optical...

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International Conference on computer Science and Software Engineering

作者： Wenxia Yang Chao Cai Mingyue Ding Chengping Zhou Key Laboratory for Image Processing and Intelligence Control of the Ministry of Education Institute of IPRAI Huazhong University of Science and Technology Wuhan China Department of Mathematics Wuhan University of Technology Wuhan China

ISBN: (纸本)9781424439027

Aero-optic effects cause distortions, including blurring, vibration, deformation and spatial shifting, of the objects in the image obtained by the infra-red sensor. Contributions of this paper are in the following two aspects. First, the correctness of the theoretical point spread function (PSF) representing the aero-optic effects, which had been derived in our previous research, is validated experimentally. Second, in order to restore the aero-optically degraded images, an improved Landweber iteration method is proposed, where, instead of being fixed, the relaxation factor is updated adaptively at each iteration. Experiments have been carried out and results demonstrate that the proposed method introduces improved restoration results with better convergence.

关键词： image restoration Degradation Infrared imaging Aircraft Educational technology Infrared sensors computer science Software engineering Chaos Laboratories

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