A zero-overhead self-timed 160-ns 54-b CMOS divider

The authors describe the design of a custom integrated circuit for the arithmetic operation of division. The chip uses self-timing to avoid the need for high-speed clocks and directly concatenates precharged function blocks without latches. Internal stages form a ring that cycles without any external signaling. The self-timed control introduces no serial overhead, making the total chip latency equal just the combinational logic delays of the data elements. The ring's data path uses embedded completion encoding and generates the mantissa of a 54-b (floating-point IEEE double-precision) result. Fabricated in 1.2-μm CMOS, the ring occupies 7 mm² and generates a quotient and done indication in 45 to 160 ns, depending on the particular data operands     

无线ATM通信网中一种新的快速越区切换方案

本文根据地无线ATM通信网中快速越区切换问题的研究,提出了一种新的基于虚道路（VP）的快速越区切换方案,并通过建立简化的呼叫模型对该方案的切换性能进行了理论分析和比较,其结果表明,该方案的各项性能均比虚拟连接树（VCT）方案和永久虚连接（PVC）方案优越。     

A novel robust logo watermarking scheme using fractional M-band wavelet transform

Digital watermarking, means of hiding/inserting a message, which can be an image, audio, video or text within the digital media. This hidden/inserting message can be later being extracted or detected for a variety of purposes. In this paper, a novel multi-resolution logo watermarking scheme using fractional M-band wavelet transform (Fr-M-band-WT) is proposed. The watermark is embedded in the multiresolution Fr-M-band-WT coefficients of low frequency bands of the host image using singular value decomposition (SVD). A multi-resolution nature of Fr-M-band-WT is exploited in the process of edge detection. Experimental results of the proposed logo watermarking scheme are compared with the previously available watermarking algorithms, fractional Fourier transform (FrFT), fractional wavelet transform (FrWT). Further, the proposed watermark extraction scheme is also tested on different attacks. The results after being investigated the proposed watermarking scheme shows a significant improvement as compared to other existing methods.     

A new recombinant in-phase microstrip power divider

The theory and design aspects of n-way in-phase power divider employing Goldfarb recombinant topology are described. The merits of this divider over conventional ones are also presented here. A microstrip version of five output port power divider is designed and developed with 1.7?mm Bakelite substrate to operate in S-band. The measured values of input VSWR, insertion loss, isolation, return loss and phase difference between output ports at different frequencies in S-band for the fabricated power divider are presented and discussed.     

A robust load-sharing control scheme for parallel-connectedmultisystems

Parallel connection of inverters or converters is one useful method for solving the high power requirements. However, a load-sharing problem among parallel-connected systems is not an easy task, since crosstalk may take place among the subsystems. We develop a general methodology for solving the load sharing problem using the master-slave concept. In synthesizing the input to the slave system, we utilize system-dynamics-dependent filters. With the proposed method, we can equally distribute the load, or can give a certain offset (in load) to a specific subsystem. To show the usefulness of the proposed control scheme, we perform a simulation study with two practical systems: a current-balancing control in parallel-connected pulsewidth modulation converters and a speed and tension control for a bridle roll system in a steel mill     

A feature-based robust digital image watermarking scheme

A robust digital image watermarking scheme that combines image feature extraction and image normalization is proposed. The goal is to resist both geometric distortion and signal processing attacks. We adopt a feature extraction method called Mexican hat wavelet scale interaction. The extracted feature points can survive a variety of attacks and be used as reference points for both watermark embedding and detection. The normalized image of an image (object) is nearly invariant with respect to rotations. As a result, the watermark detection task can be much simplified when it is applied to the normalized image. However, because image normalization is sensitive to image local variation, we apply image normalization to nonoverlapped image disks separately. The disks are centered at the extracted feature points. Several copies of a 16-bit watermark sequence are embedded in the original image to improve the robustness of watermarks. Simulation results show that our scheme can survive low-quality JPEG compression, color reduction, sharpening, Gaussian filtering, median filtering, row or column removal, shearing, rotation, local warping, cropping, and linear geometric transformations.     

A fast IP routing lookup scheme

A major issue in router design for the next generation Internet is the fast IP address lookup mechanism. The existing scheme by Huang et al. (see Proc. IEEE INFOCOM'99, New York, NY, 1999) performs the IP address lookup in hardware in which the forwarding table can be compressed to fit into a reasonable-size SRAM, and a lookup can be accomplished in three memory accesses. We claim that with a little extra memory, it is able to further reduce the lookup time to two memory accesses     

A fast adaptive resonance suppression scheme for high-damping system using R-SDFT detection

Adaptive notch filter resonance suppression scheme is widely used in high-performance servo drivers. For high-damping system, the deviation between resonant and oscillation frequency will cause a long sustained vibration in traditional suppression schemes, which may damage the precision machine irreparably. To reduce the harm of sustained vibration, a fast adaptive notch filter scheme based on range-shifted discrete Fourier transform (R-SDFT) is proposed. Different from the traditional scheme, the new one eliminates the deviation between resonant and oscillation frequency by notch filter other than the low-pass filter, which massively simplifies the suppression process and reduces the number of oscillation frequency detection required. Meanwhile, an oscillation detection method based on R-SDFT is presented to shorten the time of the detective process through interval detection and prediction strategy. Compared with the traditional strategy, the experimental results demonstrate that the proposed adaptive suppression scheme can reduce the oscillation time by more than half.     

A fast multicast IP-routing lookup scheme

This paper proposes a fast multicast IP-routing lookup scheme, which adopts a compression bit map conception for forwarding information. The proposed scheme can achieve fast address lookup speed and reasonable forwarding table size.     

Correlation-aided distributed sample acquisition scheme for fast and robust code synchronization in cellular DS-CDMA systems

We introduce a correlation-aided distributed sample acquisition (CDSA)-based intercell synchronous direct-sequence code-division multiple-access (DS/CDMA) system for enhancing the robustness of the previously proposed distributed sample acquisition (DSA)-based system. The CDSA system incorporates the state symbol correlation process in the existing DSA process to maintain the fast acquisition performance even under very poor channel environment. For its realization, each CDSA-based mobile station stores in its memory a period of the possible state symbol sequences, which are determined by the long-period scrambling PN sequences used in the system and the sampling time parameters for the state samples. In the first stage of the synchronization procedure, the mobile station (MS) attempts to acquire the psuedo noise (PN) sequence by taking the comparison-correction based synchronization approach of the original DSA scheme. However, if it cannot acquire the synchronization until it collects a predetermined number of state symbols (e.g., a period of the state symbol sequence), then the MS determines the PN sequence timing by correlating the received symbol sequence with each shift of the prestored state symbol sequences. Performance analysis and simulation results reveal strong robustness of the CDSA-based system in low-signal-to-noise ratio, fading, and large frequency-offset channels.     

A new 3-dB power divider for millimeter-wavelengths

This paper presents a new type of 3-dB power divider that achieves wideband, low-loss, and symmetric power division. In the paper, we discuss the design considerations and present results of measurements at 10 and 100 GHz. The power divider symmetry is examined as a function of the termination loads mismatch. The simplicity of the presented divider makes it very suitable for application at millimeter and submillimeter bands. The predicted and the measured performance are in very good agreement     

A fast dynamic DC-link power-balancing scheme for a PWMconverter-inverter system

The authors propose a new power converter control scheme for a converter-inverter system. The strategy is to fully utilize the inverter dynamics in controlling the converter dynamics. The authors obtain the power dynamics for both converter and inverter systems, and control the converter power so that it matches the required inverter power exactly. Then, in the ideal case, no power flows through the DC-link capacitors and, thus, the DC-link voltage does not fluctuate even though a very small amount of the DC-link capacitance is used. In forcing the converter power to match the inverter power, the authors utilize the master-slave control concept. They control the DC-link voltage level indirectly through the stored capacitor energy in order to exploit the advantage of the linear dynamic behavior of the capacitor energy. This helps them to circumvent a complex control method in regulating the DC-link voltage. Through simulation and experimental results, the superiority of the proposed converter control scheme is demonstrated     

基于螺旋电感的Wilkinson功分器设计

Wilkinson功分器是一种常用的无源器件,随着通信设备小型化的要求越来越高,无源器件的体积成为其发展瓶颈。为解决这个问题,在分析螺旋电感主要参数及等效电路基础上,提出了一种基于π型等效1/4波长传输线原理,利用集总参数元件组成等效微带线电路的集总参数方法,设计出Si沉底上的螺旋电感和片上电容来实现微波单片集成(MMIC)电路的Wil-kinson功分器。实验表明,同等性能情况下,该方法设计的Wilkinson功分器可以有效减少Wil-kinson功分器的外形尺寸。     

A robust self-calibrating transmission scheme for on-chip networks

Systems-on-Chip (SoC) design involves several challenges, stemming from the extreme miniaturization of the physical features and from the large number of devices and wires on a chip. Since most SoCs are used within embedded systems, specific concerns are increasingly related to correct, reliable, and robust operation. We believe that in the future most SoCs will be assembled by using large-scale macro-cells and interconnected by means of on-chip networks. We examine some physical properties of on-chip interconnect busses, with the goal of achieving fast, reliable, and low-energy communication. These objectives are reached by dynamically scaling down the voltage swing, while ensuring data integrity-in spite of the decreased signal to noise ratio-by means of encoding and retransmission schemes. In particular, we describe a closed-loop voltage swing controller that samples the error retransmission rate to determine the operational voltage swing. We present a control policy which achieves our goals with minimal complexity; such simplicity is demonstrated by implementing the policy in a synthesizable controller. Such a controller is an embodiment of a self-calibrating circuit that compensates for significant manufacturing parameter deviations and environmental variations. Experimental results show that energy savings amount up to 42%, while at the same time meeting performance requirements.     

Incremental algorithm-a new fast backprojection scheme for parallel beam geometries

A fast backprojection scheme for parallel beam geometries is proposed. Known as the incremental algorithm, it performs backprojection on a ray-by-ray (beam-by-beam) basis rather than the pixel-by-pixel backprojection in the conventional algorithm. By restructuring a conventional backprojection algorithm, the interdependency of pixel computations (position and value) is transformed to a set of incremental relations for a beam, where a beam is a set of pixels enclosed by two adjacent rays in 2-D computed tomography (CT), and a set of voxels enclosed by four adjacent rays in 3-D CT. To minimize the overhead of searching for the next pixels, a searching flow technique has been developed to implement the first-order and second-order incremental relations for 2-D and 3-D CTs, respectively. The values of all the pixels in each beam (except the first pixel) are computed with additions only, the key idea of the proposed backprojection scheme. The incremental algorithm has been implemented on two different machines and compared to B.F. Shepp and L.A. Logan's (1974) algorithm. The present implementation results show the superiority of this approach over the conventional algorithm.     

OBS网络中支持实时业务的管道机制

在分析光突发交换网络时延的基础上,提出了一种有效支持实时业务的管道机制.在边缘节点与核心节点之间建立通信管道.实时业务的突发控制包通过管道的核心节点时,不需要被处理,其处理时间为零,因而减少了偏置时间和网络时延.同时也降低了核心节点处理突发控制包的次数,降低了核心节点的实现复杂度.仿真结果表明,管道机制能有效降低实时业务的端对端时延.     

A tunable CMOS Wilkinson power divider using active inductors

This paper presents the design and implementation of a tunable CMOS Wilkinson power divider using active inductors. Compared to a conventional active inductor topology, the proposed active inductor features higher inductance tuning range, higher self-resonant frequency, and lower power consumption by introducing two additional transistors. Benefitting from the superior inductor, the low-loss Wilkinson power divider is practical while maintaining a wide tuning range. The design consuming 10.2 mW demonstrates an insertion loss of 0.67 dB, a return loss of 27 dB, and an isolation of 22.6 dB at 8 GHz. Moreover, the tuning range of the circuit is between 5.8 GHz and 10.4 GHz, rendering a 4.6 GHz bandwidth. The active chip size of the lumped design is merely 0.25 mm × 0.15 mm.     

采用小波变换的鲁棒隐形水印算法

本文提出了一种小波域透明图像水印算法,算法将一个二进制随机水印信号内嵌到一组按重要性选出的小波系数中,为了使透明水印具有较高的鲁棒性,内嵌过程将水印信号将为量化噪声嵌入小波零树编码的数字图像,实验获得了良好的结果。     

A robust cluster-based dynamic-super-node scheme for hybrid peer-to-peer network

Hybrid peer-to-peer (P2P) system can improve the performance of the entire system using super-peer. But it is difficult to measure a peer's capability exactly and ensure high reliability of the network. This paper proposes a scheme to solve these problems. Firstly, we present a hybrid P2P network in which the upper layer is Chord network and the lower layer is cluster. Then we provide a strategy to measure a peer's capability so that a cluster can be organized to be a sorting network in which peers are classified into three types dynamic-super-node (DSN), backup-node (BN) and ordinary-node (ON). In a cluster, DSN and BNs are strongly connected. And based on this, we present an algorithm DSN flood min (DSNFM) to select DSN BN and maintain consensus of the cluster. Furthermore, we do a reliability analysis of the cluster based on churn rate of the network and gathered three rules of thumb from our simulations.