A New Approach to Variable Selection Using the TLS Approach

The problem of variable selection is one of the most important model selection problems in statistical applications. It is also known as the subset selection problem and arises when one wants to explain the observations or data adequately by a subset of possible explanatory variables. The objective is to identify factors of importance and to include only variables that contribute significantly to the reduction of the prediction error. Numerous selection procedures have been proposed in the classical multiple linear regression model. We extend one of the most popular methods developed in this context, the backward selection procedure, to a more general class of models. In the basic linear regression model, errors are present on the observations only, if errors are present on the regressors as well, one gets the errors-in-variables model which for Gaussian noise becomes the total-least-squares (TLS) model, this is the context considered here     

A New QoS Resource Allocation Scheme Using GTS for WPANs

IEEE 802.15.4 (for low-rate Wireless Personal Area Networks??WPANs) (IEEE 802.15.4 Standard-2003) and IEEE 802.15.7 (for Short-Range Wireless Optical Communication Using Visible Light) (IEEE 802.15.7 Standard??2011) are two typical standards for WPANs that support Quality-of-Service (QoS) through a Guaranteed Time Slot (GTS) mechanism to allocate a specific duration within a superframe structure for a time division multiplexing transmission. The low bandwidth utilization problem may occur in the GTS mechanism when the allocated bandwidth is less than the available bandwidth. However, this problem has not been resolved thoroughly in any of the standard or current research thus far. This paper analyzes GTS performance in QoS-guaranteed transmission and proposes a new GTS allocation scheme named Unbalanced GTS Allocation Scheme (UGAS), which improves the bandwidth resource efficiency. Our scheme tries to solve the bandwidth under-utilization problem by using Network Calculus theory based on the fluid model and greedy algorithm. The UGAS scheme divides the Contention-Free Period into time slots of different durations to support various bandwidth requirements. Time slots are allocated using an approximation QoS model to minimize under-utilization. Compared with the standard GTS allocation scheme, UGAS makes an efficient bandwidth allocation with the QoS-guaranteed model and without breaking the standard protocol. The numerical results show that the average bandwidth utilization using UGAS can be improved by 30 % as compared with the standard scheme.     

A New MPEG-2 Rate Control Scheme Using Scene Change Detection

We propose two new rate control schemes to improve MPEG-2 rate control in view of visual quality when scene changes happen. Two proposed schemes are characterized by real-time and non real-time improvement to reduce the impact of scene changes. We also propose a new target-bit prediction method using spatial activity of pictures and present a simple and efficient scene change detection scheme using signed difference of mean absolute difference (MAD). Computer simulation results show that the proposed real-time algorithm effectively alleviates visual quality degradation after scene changes. The proposed non real-time algorithm gives maximum 2 dB improvement in peak signal-to-noise ratio (PSNR) at a scene-changed picture, compared with MPEG-2 rate control scheme and it shows better quality than the real-time one.     

一种新的自动多阈值图像分割方法

本文提出了一种新的自动阈值图像分割方法.该方法选择二维灰度直方图的最佳一维投影作为输入信息,并利用了小波变换的多尺度特征分析此投影.在大尺度下抑制噪声并自动确定分割类数,在小尺度下精确定位阈值.实验表明新方法能够自动而快速地对图像进行分割而且有较强的抗干扰能力.     

A Multi-Objective Optimization Scheme for Multicast Routing: A Multitree Approach

In this paper, we propose a multi-objective traffic engineering scheme using different distribution trees to multicast several flows. The aim is to combine into a single aggregated metric, the following weighting objectives: the maximum link utilization, the hop count, the total bandwidth consumption, and the total end-to-end delay. Moreover, our proposal solves the traffic split ratio for multiple trees. We formulate this multi-objective function as one with Non Linear programming with discontinuous derivatives (DNLP). Results obtained using SNOPT solver show that several weighting objectives are decreased and the maximum link utilization is minimized. The problem is NP-hard, therefore, a novel SPT algorithm is proposed for optimizing the different objectives. The behavior we get using this algorithm is similar to what we get with SNOPT solver. The proposed approach can be applied in MPLS networks by allowing the establishment of explicit routes in multicast events. The main contributions of this paper are the optimization model and the formulation of the multi-objective function; and that the algorithm proposed shows polynomial complexity.     

A New ICI Matrices Estimation Scheme Using Hadamard Sequence for OFDM Systems

The intercarrier interference (ICI) matrix for the orthogonal frequency division multiplexing (OFDM) systems usually has a fairly large dimension. The traditional least-square solution based on the pseudo-inverse operation, therefore, has its limitation. In addition, the provision of a sufficiently long training sequence to estimate the complete ICI matrix is not feasible, since it will result in severe throughput reduction. In this paper, we derive a lower bound for the mean-square estimation error among the least-square ICI matrix estimators using different training sequences and prove that the minimum mean-square error (MMSE) optimality is attained when the training sequences in different OFDM blocks are orthogonal to each other, regardless of the sequence length. We also prove that the asymptotical mean-square estimation error using the maximal-length shift-register sequences ($m$-sequences) as in the existing communication standards is 3 dB larger than that using the perfectly orthogonal sequences for ICI matrix estimation. Thus, we propose to employ the training sequences based on the Hadamard matrix to achieve a highly efficient and optimal ICI matrix estimator with minimum mean-square estimation error among all least-square ICI matrix estimators. Meanwhile, our new scheme involves only square computational complexity, while other existing least-square methods require the complexity proportional to the cube of the ICI matrix size. Analytical and experimental comparisons between our new scheme using Hadamard sequences and the existing method using$m$-sequences (pseudo-random sequences) show the significant advantages of our new ICI matrix estimator. The proposed method is most suitable for OFDM systems with large amount of subcarriers, using high order of subcarrier modulation, and designed for high-end of RF frequency band, where accurate ICI estimation is crucial.     

一种基于自适应频率估计的跳频捕获新方法

针对水声跳频通信,给出了1种基于频率估计的跳频同步捕获的捕获原理和捕获过程,捕获中采用1种简化的变专长自适应格型IIR陷波器算法估测跳频信号频率。仿真结果说明该算法在低信噪比下具有估计精度高和实时性好的特点,满足水声跳频系统捕获的要求,验证了该跳频捕获方法的优越性。     

A Novel Approach for QoS Enhancement with Revision Scheme Using SeDSR Protocol in Wireless Sensor Networks

Wireless Personal Communications - Wireless Sensor Networks (WSNs) is an emerging technology that pays more attention to the monitoring and acquiring of data in a deployed environment. Sensor...     

A New Space-Time Multiple Trellis Coded Modulation Scheme Using Transmit Symbol Phase Rotation

Space-time multiple trellis coded modulation (ST-MTCM) has been introduced in order to achieve maximum transmit diversity gain and larger coding gain with the existence of parallel paths. In our previous research, we designed a new coded modulation scheme for ST-MTCM which simultaneously maximizes the coding gain and diversity gain utilizing Hadamard Matrix giving the maximum determinant. This scheme, however, cannot achieve full transmit rate. In this paper, we extend our research so as to achieve full rate transmission as well as maximum coding and diversity gain. In addition, Super-Orthogonal Space-Time Trellis Code (SO-STTC) is well known for its high coding gain, full diversity gain and full transmit rate. Even though our proposed scheme is essentially the same as SO-STTC, we show in this paper that our proposed code design is different from SO-STTC, and achieves better performance. Our proposed code design utilizes transmit symbol phase rotation at a certain time slot so as to avoid same path transition in trellis, which occurs with conventional SO-STTC scheme. We design codes with different way of phase rotation for different MPSK modulation scheme, and simulation results show the improvements of our proposed codes for MPSK modulation with different number of states. Susu Jiang was born in Jilin, China, in 1979. She received the B.E. and M.S. degrees in electrical and computer engineering from Yokohama National University, Yokohama, Japan, in 2001 and 2003, respectively. She is currently working toward the Ph.D. degree in electrical and computer engineering at Yokohama National University, Yokohama, Japan. Her research interests include space-time coding, channel coding in wireless communications, and information theory. She is a student member of the IEICE and IEEE. Ryuji Kohno received the Ph.D. degree from the University of Tokyo in 1984. Dr. Kohno is currently a Professor of the Division of Physics, Electrical and Computer Engineering, Yokohama National University. In his currier he was a director of Advanced Telecommunications Laboratory of SONY CSL during 1998–2002 and currently a director of UWB Technology institute of National Institute of Information and Communications Technology (NICT). In his academic activities, he was elected as a member of the Board of Governors of IEEE Information Theory (IT) Society in 2000 and 2003. He has played a role of an editor of the IEEE Transactions on IT, Communications, and Intelligent Transport Systems (ITS). He is a fellow of IEICE, vice-president of Engineering Sciences Society of IEICE and has been the Chairman of the IEICE Technical Committee on Spread Spectrum Technology, that on ITS, and that on Software Defined Radio (SDR). Prof. Kohno has contributed for organizing many international conferences, such as an chair-in honor of 2002 & 2003 International Conference of SDR (SDR'02 & SDR'03), a TPC co-chair of 2003 International Workshop on UWB Systems (IWUWBS'03), and a general co-chair of 2003 IEEE International Symposium on IT (ISIT'03), that of Joint UWBST&IWUWB'04 and so on. He was awarded IEICE Greatest Contribution Award and NTT DoCoMo Mobile Science Award in 1999 and 2002, respectively.     

一个利用模糊预测的ATM广域网流量控制算法

本文提出了一个采用模糊预测的ＡＴＭ广域网流量控制算法,该算法包括二个部分,即非受控业务量的模糊预测和网络带宽的动态分配,在预测部分,提出了一组模糊判决规则和相关的隶属函数,在带宽分配地对ＡＴＭ广域网传输时延长的特点,把模糊预测与本文作者在文献「１」中所提出的ＳＥＲ流量控制机制相结合,保证了带分配的公平性和链路的高利用率,仿真结果表明,带宽分配具有公平性,链路利用率达到设计目标、交换节点处缓冲队列很     

新的基于身份的签密方案

利用椭圆曲线上的双线性对,提出一个基于身份的签密方案。在新方案中,接收者收到一个签密消息,在验证该消息签名的合法性后,再对消息进行恢复。在安全性方面,新方案具有机密性、不可伪造性、公开可验证性、鲁棒性;在计算量和通信成本方面,新方案中只需要进行1次模指数运算、2次双线性对运算和1次双线性对预运算,签密产生的密文长度为2｜G1｜＋｜m｜,总成本比已有的基于身份的签密方案耗费少,从而有效实现了对消息的认证和保密。     

IIR Filter Adaptation Using Branch-and-Bound: A Novel Approach

Adaptive infinite impulse response (IIR) filters provide significant advantages over equivalent finite impulse response (FIR) implementations because they are able to more accurately model physical plants that have pole-zero structures. Additionally, they are typically capable of meeting performance specifications using fewer filter parameters. This savings in parameters, which can be as much as 5–10 times, leads to the use of fewer multiplier blocks and therefore, lower power consumption. Despite these advantages, adaptive IIR filters have not found widespread use because the associated mean squared error (MSE) cost function is multimodal and therefore, significantly difficult to minimize. Additionally, the filter can become unstable during adaptation. These two properties pose several problems for adaptive algorithms, causing them to be sensitive to initial conditions, produce biased solutions, unstable filter configurations or converge to local minima. These problems prevent the widespread use of adaptive IIR filters in practice and if such filter structures are to become more practical, new, innovative solutions are required. This paper proposes a new algorithm for minimizing the MSE cost function of adaptive IIR filters aimed at addressing some of the aforementioned issues. We adopt the approach of using a Branch-and-Bound algorithm, which is an exhaustive search method, and employ interval arithmetic for all computations. Simulation results show that the resulting algorithm is viable and competitive and, when compared with a number of existing state-of-the-art algorithms, outperforms them in terms of the MSE of the final point.      

Superquantile-Based Learning: A Direct Approach Using Gradient-Based Optimization

Journal of Signal Processing Systems - We consider a formulation of supervised learning that endows models with robustness to distributional shifts from training to testing. The formulation hinges...     

采用小波变换的立体匹配:一种基于相位的方法

本义提出了一种采用小波变换基于相位的立体匹配算法。该算法引入多分辨率分析思想,借助小波变换的Ｍａｌｌａｔ算法,采用金字塔式的多尺度匹配结构,从而显著地提高了匹配效率。同时,该算法利用平滑性约束条件实现了相位不稳定区域视差的自适应插值,保证了良好的匹配效果。立体象对的测试结果表明了该算法的有效性。     

Matrix Coded Modulation: A New Non-coherent MIMO Scheme

This paper describes a new space-time coding scheme for non-coherent multi-antenna Multi-Input Multi-Output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require Channel State Information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal Frequency Division Multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the Differential Space-Time Modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.     

Matrix Coded Modulation: A New Non-coherent MIMO Scheme

This paper describes a new space-time coding scheme for non-coherent multi-antenna multi-input multi-output (MIMO) systems. This new MIMO scheme merges error-correcting and space-time coding functions by transmitting invertible matrices, so this scheme has been called “Matrix Coded Modulation” or “MCM”. Coherent systems require channel state information (CSI) at the transmitters and/or at the receivers, and their performances strongly depend on the channel estimation. For example, in systems using Orthogonal frequency division multiplexing, the channel estimation requires the insertion of pilot-symbols in the transmitted frame which implies a spectral efficiency loss of the global system that increase with the number of transmit antennas. The existing non-coherent schemes such as the differential space-time modulation leads to performance degradation compared to coherent systems in which perfect CSI is assumed. Decoding in the MCM scheme is performed iteratively, based on a specified detection criteria. In the proposed MCM scheme, decoding can be achieved with or without CSI at the receiving antennas. As the space-time coding function is merged with the error-correcting code, the euclidean distances distribution between modulated signals based on the detection criteria is strongly linked to the Hamming weights distribution of the channel error-correcting code used in the MCM scheme. Moreover, a low-complexity decoding algorithm is described and compared to the existing differential schemes.     

一种新的3－D小波变换图像编码方法

基于图像序列三维小波变换的视频编码技术是一种很有潜力的编码方法．本文针对目前实际中采用的三维小波变换只是一种准三维变换，不能提供对变换结果的统一描述等不足，推导了信号真正的三维小波变换的有关理论及其实现方法．在此基础上，我们将这种三维小波变换方法用于视频图像的编码，模拟结果表明这种编码结构具有良好性能，值得进一步的深入研究．     

Robust Scene-Based Digital Video Watermarking Scheme Using Level-3 DWT: Approach,Evaluation, and Experimentation

This paper presents a robust digital video-watermarking system for copyright and copy protection. The proposed method applies the combination of discrete wavelet transform (DWT) and scene-change-detector. For better understanding, this approach can be presented in the form of four stages. The first stage is finding the frame where the watermark is to be inserted. The analysis of watermarking using the level-3 decomposition of LL subband withDWTis described in the second stage. Transparency and the robustness have been analyzed under fifteen different attacks in the third stage. Improvement in the robustness and transparency, as compare to watermarking using different levels of LL subband is calculated in terms of the normalized correlation and the structural similarity index in the fourth stage. The experimental result reveal that the proposed method yields the extracted watermark image and watermarked video of good quality and can sustain different image processing, JPEG compression and geometrical attacks. Empirical results prove the improvement in the performance as the decomposition level increases from level-1 to level-3. Comparative analysis with the existing schemes proves the improved robustness, better imperceptibility and the reduced computational time of the proposed scheme.