In this paper a straight-forward approach to extract the equivalent loop-gain of a continuous time Delta-Sigma modulator with an arbitrary DAC waveform in z-domain is presented. In this approach the arbitrary DAC waveform is approximated by the infinite number of rectangular pulse shapes. Then simply using the transformations available in literatures for a rectangular DAC pulse shape and applying superposition on each rectangular pulse shape, the loop-gain of the system is derived in z-domain.

A hardware algorithm for modular multiplication/division which performs modular division, Montgomery multiplication, and ordinary modular multiplication is proposed. The modular division in our algorithm is based on the extended Euclidean algorithm. We employ our newly proposed computation method that consists of processing the multiplier from the most significant digit first to calculate Montgomery multiplication. Finally, the ordinary modular multiplication is based on shift-and-add multiplication. Each of these three operations is carried out through the iteration of simple operations such as shifts and additions/subtractions. To avoid carry propagation in all additions and subtractions, the radix-2 signed-digit representation is employed. A modular multiplier/divider based on the algorithm has a linear array structure with a bit-slice feature and carries out n-bit modular multiplication/division in O(n) clock cycles, where the length of the clock cycle is constant and independent of n. This multiplier/divider can be implemented using a hardware amount only slightly larger than that of the modular divider.

Many parallel Fast Fourier Transform (FFT) algorithms adopt multiple stages architecture to increase performance. However, data permutation between stages consumes volume memory and processing time. One FFT array processing mapping algorithm is proposed in this paper to overcome this demerit. In this algorithm, arbitrary 2k butterfly units (BUs) could be scheduled to work in parallel on n=2s data (k=0,1,..., s-1). Because no inter stage data transfer is required, memory consumption and system latency are both greatly reduced. Moreover, with the increasing of BUs, not only does throughput increase linearly, system latency also decreases linearly. This array processing orientated architecture provides flexible tradeoff between hardware cost and system performance. In theory, the system latency is (s2s-k)tclk and the throughput is n/(s2s-ktclk), where tclk is the system clock period. Based on this mapping algorithm, several 18-bit word-length 1024-point FFT processors implemented with TSMC0.18 µm CMOS technology are given to demonstrate its scalability and high performance. The core area of 4-BU design is 2.9911.121 mm2 and clock frequency is 326 MHz in typical condition (1.8 V,25). This processor completes 1024 FFT calculation in 7.839 µs.

In recent years, the demand for multimedia mobile battery-operated devices has created a need for low power implementation of video compression. Many compression standards require the discrete cosine transform (DCT) function to perform image/video compression. For this reason, low power DCT design has become more and more important in today's image/video processing. This paper presents a new power-efficient Hybrid DCT architecture which combines Loeffler DCT and binDCT in terms of special property on luminance and chrominance difference. We use Synopsys PrimePower to estimate the power consumption in a TSMC 0.25-µm technology. Besides, we also adopt a novel quality assessment method based on structural distortion measurement to measure the quality instead of peak signal to noise rations (PSNR) and mean squared error (MSE). It is concluded that our Hybrid DCT offers similar quality performance to the Loeffler, and leads to 25% power consumption and 27% chip area savings.

Time-Division-Multiplexing (TDM) is usually aimed at digital signals, while Continuous Wave Time-Division- Multiplexing (i.e. CWTDM) presented in this paper mainly addresses the problem of multiple continuous signals to share a channel. According to the idea in Ref.[1], this paper proposes a novel method for implementing CWTDM, which can make multiple band-limited continuous signals time-division-multiplexed into one continuous signal without significantly expanding the frequency band. The new method has several important applications. In particular, it can be used to implement an on-board FDMA-CWTDM conversion to develop a new system of satellite communications with more efficient performance.

This paper addresses the parameter estimation problem of an interval-based hybrid dynamical system (interval system). The interval system has a two-layer architecture that comprises a finite state automaton and multiple linear dynamical systems. The automaton controls the activation timing of the dynamical systems based on a stochastic transition model between intervals. Thus, the interval system can generate and analyze complex multivariate sequences that consist of temporal regimes of dynamic primitives. Although the interval system is a powerful model to represent human behaviors such as gestures and facial expressions, the learning process has a paradoxical nature: temporal segmentation of primitives and identification of constituent dynamical systems need to be solved simultaneously. To overcome this problem, we propose a multiphase parameter estimation method that consists of a bottom-up clustering phase of linear dynamical systems and a refinement phase of all the system parameters. Experimental results show the method can organize hidden dynamical systems behind the training data and refine the system parameters successfully.

A polynomial expansion linear detector (PELD) based turbo receiver is proposed for single-carrier zero-padding block transmission (ZP-SCBT) systems over the single-input single-output (SISO) and multiple-input multiple-output (MIMO) frequency selective channels. The performance is compared with the minimum mean square error (MMSE) and match filter (MF) based turbo receivers. It is shown that the PELD-based turbo receiver provides a good trade-off between performance and complexity compared with the other two alternatives.

In a conventional method based on quadrature 2D Gabor wavelets to extract iris features, the iris recognition is performed by a 256-byte iris code, which is computed by applying the Gabor wavelets to a given area of the iris. However, there is a code redundancy because the iris code is generated by basis functions without considering the characteristics of the iris texture. Therefore, the size of the iris code is increased unnecessarily. In this paper we propose a new feature extraction algorithm based on independent component analysis (ICA) for a compact iris code. We implemented the ICA to generate optimal basis functions which could represent iris signals efficiently. In practice the coefficients of the ICA expansions are used as feature vectors. Then iris feature vectors are encoded into the iris code for storing and comparing individual's iris patterns. Additionally, we introduce a method to refine the ICA basis functions for improving the recognition performance. Experimental results show that our proposed method has a similar equal error rate as a conventional method based on the Gabor wavelets, and the iris code size of our proposed methods is five times smaller than that of the Gabor wavelets.

An adaptive transmission scheme, in which the work in [3] is extended to multiuser environment, is proposed for LDPC-coded MIMO-OFDMA cellular systems that employ FDD by considering active user selection and sub-channel power allocation. The performance of the proposed scheme is obtained from simulation and compared with that of the conventional scheme using mean SNR only. It is shown that the proposed scheme can provide up to 5.5 dB gain over the conventional scheme at the expense of only 6 more bits in feedback information.

In this paper, a three-way divider is proposed for a partially-corporate feed in an alternating phase-fed single-layer slotted waveguide array. The divider is placed at the middle of the feed waveguide and reduces the long line effects; the frequency bandwidth is doubled. It is a kind of cross junction with one input port and three output ports; most of the power is equally divided into the right and left halves of the feed waveguide while the rest of power goes straight into the center radiating waveguide. Based upon the moment method design of the three-way divider, an inductive post is introduced for wide band power dividing control to the radiating waveguide. Reflection is below -20 dB over a wide bandwidth of 24.3-26.3 GHz, and the range of power dividing ratio ranges from 1/43 to 1/4. The amplitude and the phase from the two output ports to the feed waveguide are well balanced, and the differences are less than 0.1 dB and 5.0 degrees, respectively. The MoM analysis and the wide band design are verified experimentally in the 4 GHz band.

It is known that the thickness of the λ/4 type EM wave absorber having a resistive film with the capacitive reactance is thinner than 1/4 wavelength. This paper investigates EM wave absorbers using the resistive film with capacitive reactance. We introduced the impedance into the resistive film, and then clarified the relationship between the impedance and the matching thickness in the single layer EM wave absorber. Practically, we carried out to grasp the impedance of the resistive films, which were prepared using the conductive flake powder. As the results, we have proven that the matching thickness in the single layer EM wave absorber could be realized 0.17 λ-0.09 λ in the frequency range from 2 GHz to 8 GHz by using these resistive films. We also fabricated the single resistive layer and the double resistive layers EM wave absorber using these resistive films for Dedicated Short Range Communications (DSRC) and wireless Local Area Network (LAN), in which the matching thickness could be reduced to 45% and 30%, respectively, as compared with the each absorber using the non-capacitive reactance.

This paper proposes a new detection ordering scheme, which minimizes average error rate of the MIMO system with per antenna rate control. This paper shows an optimal scheme minimizing average error rate expressed by the Q function, and simplifies the optimal scheme by using the minimum equivalent SINR scaled by modulation indices, based on approximated error rate. In spite of reduced complexity, the simplified scheme demonstrates the almost same performance as the optimal scheme. Owing to the diversity of detection ordering, the proposed scheme has over 2 dB higher SNR gain at the BER of 10-3 than the existing ordering schemes in balanced array size systems.

The minimum initial marking problem MIM of Petri nets is described as follows: "Given a Petri net and a firing count vector X, find an initial marking M0, with the minimum total token number, for which there is a sequence δ of transitions such that each transition t appears exactly X(t) times in δ, the first transition is enabled at M0 and the rest can be fired one by one subsequently." This paper proposes two heuristic algorithms AAD and AMIM + and shows the following (1) and (2) through experimental results: (1) AAD is more capable than any other known algorithm; (2) AMIM + can produce M0, with a small number of tokens, even if other algorithms are too slow to compute M0 as the size of an input instance gets very large.

An energy-efficient power-aware design is highly desirable for DSP functions that encounter a wide diversity of operating scenarios in battery-powered wireless sensor network systems. Addressing this issue, this letter presents a low-power power-aware scalable pipelined Booth multiplier that makes use of dynamic-range detection unit, sharing common functional units, ensemble of optimized Wallace-trees and a 4-bit array-based adder-tree for DSP applications.

This paper proposes a backlight module which drives multiple cold-cathode fluorescent lamps (CCFLs) with a current mirror technique to equalize the driving current for each lamp. We first adopt a half-bridge parallel-resonant inverter as the main circuit and use a single-input, multiple-output transformer to drive the multi-CCFLs. Next, we introduce current-mirror circuits to create a new current-sharing circuit, in which its current reference node and the parallel-connected multi-load nodes are used to accurately equalize all CCFLs' driving current. This will balance each lamp's brightness and, consequently, improve the picture display quality of the related liquid crystal display (LCD). This paper details the design concept for each component value with the assistance of an actual design example. The results of the example are examined with its actual measurements, which consequently verify the correctness of the proposed control strategy.

Because of the large scale of wireless sensor networks, the configuration needs to be done autonomously. In this paper, we present Scalable Data Collection (SDC) protocol, a tree-based protocol for collecting data over multi-hop, wireless sensor networks. The design of the protocol aims to satisfy the requirements of sensor networks that every sensor transmits sensed data to a sink node periodically or spontaneously. The sink nodes construct the tree by broadcasting a solicit packet to discover the child nodes. The sensor receiving this packet decides on an appropriate parent to which it will attach, it then broadcasts the same packet to discover its child nodes. Through this process, the tree is created autonomously without any flooding of the routing packets. SDC avoids periodic updating of routing information but the tree need to be reconstructed upon node failures or adding of new nodes. The states required on each sensor are constant and independent of network size, therefore SDC scales better than the existing protocols. Moreover, each sensor can make forwarding decisions regardless of the knowledge on geographical information. We evaluated the performance of SDC by using the ns-2 simulator and comparing with Directed Diffusion, DSR, AODV, and OLSR. The simulation results demonstrate that SDC achieves much higher delivery ratio, shorter delay, as well as high scalability in various scenarios.

Driving methods for TFT-OLEDs are explained with their features and classified from the viewpoints of grayscale methods and uniformizing methods. This classification leads us to a novel proposal using time ratio grayscale and current uniformization. This driving method maintains current uniformity and simultaneously overcomes charging shortage of the pixel circuit for low grayscale levels and current variation due to the shift of operating points. Tolerance toward degraded characteristics, linearity of grayscale and luminance uniformity against degraded characteristics are confirmed using circuit simulation.

This paper proposes two space-time joint channel parameter estimation and signal detection algorithms for downlink DS-CDMA systems with multiple-input-multiple-output (MIMO) wireless multipath fading channels. The proposed algorithms initially use the space-time MUSIC to estimate the DOA-delays of the multipath channel. Based on these estimated DOA-delays, a space-time channel decoupler is developed to decompose the multipath downlink channel into a set of independent parallel subchannels. The fading amplitudes of the multipath can then be estimated from the eigen space of the output of the space-time channel decoupler. With these estimated channel parameters, signal detection is carried out by a maximal ratio combiner on a pathwise basis. Computer simulations show that the proposed algorithms outperform the conventional space-time RAKE receiver while having the similar performance compared with the space-time minimum mean square error receiver.

In 2002, Zhu et al. proposed a password-based authenticated key exchange protocol based on RSA. Zhu et al. claimed the protocol is efficient for the low-power devices in wireless networks. Unfortunately, Yeh et al. pointed out that Zhu et al.'s protocol was weak against undetectable on-line password guessing attack. Not only that, Zhu et al.'s protocol does not achieve explicit key authentication. At the same time, Yeh et al. proposed an improved method. However, in this paper, we shall point out that Yeh et al.'s improvement is vulnerable to the off-line password guessing attack. At the same time, we shall propose a solution to resist the above attack.

In this paper, we propose a new concept of receiver structure with diversity reception technique to realize multi-service simultaneous reception, which shares diversity branches between receiving communication services. In the proposed receiver structure, each diversity branch selects the receiving services dynamically according to channel states, and each communication service is always selected by at least one branch to realize multi-service simultaneous reception. A basic algorithm is also described to select combinations of a diversity branch and a receiving communication service. The total number of branches decreases and the effective number of branches per communication service increases, by sharing the branches between communication services in the proposed receiver. Simulation results are shown that the proposed diversity receiver achieves both complexity reduction and performance improvement.