A major drawback in OFDM systems is that the transmit-signal exhibits a high Peak-to-Average Power Ratio (PAPR) which causes nonlinear distortion at the output of power amplifier. To achieve high efficiency in OFDM systems, it is important to suppress PAPR of the transmit signal. In IEEE802.16e (mobile WiMAX) based systems, it is desirable to employ a simple PAPR reduction method such as clipping & filtering (C&F) or peak windowing (PW). The purpose of this paper is to evaluate PAPR reduction performance of C&F and PW and compare them in an IEEE802.16e based OFDM system. In addition, we also show a repeated PW method which reduces PAPR by repeatedly applying a smooth window function to the transmit signal. Computer simulation results show that the repeated PW can achieve almost the same PAPR reduction performance as that of the repeated C&F with significantly lower computational complexity.

EIRP measurement in the direction of maximum radiation has not always been valid to estimate the radiated power from radio equipments integrated with antennas, for example, integrated radiator with antennas shaped like the notebook-sized PC. Therefore, it is recommended that total radiated power (TRP) from equipment under test (EUT) should be estimated by integrating measured EIRPs on the whole surface of the unit sphere. In this paper, a conventional and some novel sampling methods for the TRP estimation, which were proposed to reduce the number of measurement points, are examined by using a measured EIRP data set and compared with each other. For a simulated radio equipment shaped like a notebook-sized PC, it is found that the equi-area and generalized spiral points methods are superior to the equi-angle method in terms of reducing the number of the measurement points and orthogonal three planes method is another candidate in terms of saving measurement time unless the pattern radiated from EUT is not so complicated.

Recently, assuming ideal brick-wall transmit filtering, we proposed a frequency-domain block signal detection (FDBD) with maximum likelihood detection employing QR decomposition and M-algorithm (called QRM-MLD) for the reception of single-carrier (SC) signals transmitted over a frequency-selective fading channel. QR decomposition (QRD) is applied to a concatenation of the propagation channel and discrete Fourier transform (DFT). However, a large number of surviving paths is required in the M-algorithm to achieve sufficiently improved bit error rate (BER) performance. The introduction of filtering can achieve improved BER performance due to larger frequency diversity gain while keeping a lower peak-to-average power ratio (PAPR) than orthogonal frequency division multiplexing (OFDM). In this paper, we develop FDBD with QRM-MLD for filtered SC signal reception. QRD is applied to a concatenation of transmit filter, propagation channel, and DFT. We evaluate BER and throughput performances by computer simulation. From performance evaluation, we discuss how the filter roll-off factor affects the achievable BER and throughput performances and show that as the filter roll-off factor increases, the required number of surviving paths in the M-algorithm can be reduced.

A new structure to improve channel capacity of short-range MIMO is proposed. The proposed structure consists of back reflector and side reflector. FDTD simulation demonstrates a role of back reflector and side reflector. The back reflector increases all eigen values. The side reflector equalizes eigen value distribution. Consequently, the proposed structure enhances the channel capacity.

Energy conservation is an important issue in mobile ad hoc networks (MANET), where the terminals are always supplied with limited energy. A new routing protocol is presented according to the study on the influence of low-energy nodes in ad hoc networks. The novel routing protocol (energy sensing routing protocol, ESRP) is based on the energy sensing strategy. Multiple strategy routing and substitute routing are both adopted in this paper. Referring to the level of the residual energy and the situation of energy consumption, different routes are chosen for packets transmission. The local maintenance is adopted, which can reduce packets retransmission effectively when the link breaks. We focus on the network lifetime most in all performances. The evaluation is done in comparison with other routing protocols on NS2 platform, and the simulation results show that this routing protocol can prolong the network lifetime and balance energy consumption effectively.

This paper introduces an interactive expression editing system that allows users to design facial expressions easily. Currently, popular example-based methods construct face models based on the examples of target face. The shortcoming of these methods is that they cannot create expressions for novel faces: target faces not previously recorded in the database. We propose a solution to overcome this limitation. We present an interactive facial-geometric-feature animation system for generating expressions of novel faces. Our system is easy to use. By click-dragging control points on the target face, on the computer screen display, unique expressions are generated automatically. To guarantee natural animation results, our animation model employs prior knowledge based on various individuals' expressions. One model prior is learned from motion vector fields to guarantee effective facial motions. Another, different, model prior is learned from facial shape space to ensure the result has a real facial shape. Interactive animation problem is formulated in a maximum a posterior (MAP) framework to search for optimal results by combining the priors with user-defined constraints. We give an extension of the Motion Propagation (MP) algorithm to infer facial motions for novel target faces from a subset of the control points. Experimental results on different facial animations demonstrate the effectiveness of the proposed method. Moreover, one application of our system is exhibited in this paper, where users create expressions for facial sketches interactively.

In the face of constant malicious attacks to network-connected software systems, software vulnerabilities need to be discovered early in the development phase. In this paper, we present AspFuzz, a state-aware protocol fuzzer based on the specifications of application-layer protocols. AspFuzz automatically generates anomalous messages that exploit possible vulnerabilities. The key observation behind AspFuzz is that most attack messages violate the strict specifications of application-layer protocols. For example, they do not conform to the rigid format or syntax required of each message. In addition, some attack messages ignore the protocol states and have incorrect orders of messages. AspFuzz automatically generates a large number of anomalous messages that deliberately violate the specifications of application-layer protocols. To demonstrate the effectiveness of AspFuzz, we conducted experiments with POP3 and HTTP servers. With AspFuzz, we can discover 20 reported and 1 previously unknown vulnerabilities for POP3 servers and 25 reported vulnerabilities for HTTP servers. Two vulnerabilities among these can be discovered by the state-awareness of AspFuzz. It can also find a SIP state-related vulnerability.

This paper presents a circuit that improves supply noise rejection using an active inductor circuit. Compared to the conventional designs, the proposed supply noise suppression circuit has better characteristics such as low current consumption and small die size with noise rejection. The circuit was fabricated using 0.13 µm UMC CMOS technology. The experimental results showed that the supply noise was suppressed by 61% with only an increase in size of 20.0 µm 2.5 µm, and the current consumption was under 2 mA.

This paper presents an ultra-wideband amplifier embedded with band-pass filter design. The scattering parameters of a frequency-domain GaAs field effect transistor are converted into z-domain representations by employing the weighted linear least squares method. A least squares scheme is employed to obtain characteristic impedances of transmission line elements that form the amplifier having a flat gain in the passband and good fall-off selectivity in the stopband. Experimental results illustrate the validity of the proposed design method.

High-power protection switch utilizing a new stub/line selectable configuration is presented. By employing the proposed circuit topology, the insertion loss at receiving mode and the power handling capability at transmitting mode can be independently designed. Therefore, the proposed circuit is able to achieve low insertion loss at receiving mode while keeping high-power performance at transmitting mode. To verify this methodology, MMIC switch has been fabricated in Ka-band. The circuit has achieved the insertion loss of 2 dB, the isolation of 25 dB, and the power handling capability of 40 dBm at 5% bandwidth.

In this paper, we propose a spatially adaptive gradient-projection algorithm for the H.264 video coding standard to remove coding artifacts using local statistics. A hybrid method combining a new weighted constrained least squares (WCLS) approach and the projection onto convex sets (POCS) approach is introduced, where weighting components are determined on the basis of the human visual system (HVS) and projection set is defined by the difference between adjacent pixels and the quantization index (QI). A new visual function is defined to determine the weighting matrices controlling the degree of global smoothness, and a projection set is used to obtain a solution satisfying local smoothing constraints, so that the coding artifacts such as blocking and ringing artifacts can be simultaneously removed. The experimental results show the capability and efficiency of the proposed algorithm.

A switched-capacitor integrator based on dynamic source follower amplifiers has been proposed. Integrator operation has been confirmed and analyzed by assuming 0.18-µm CMOS technology. The integrator can reduce the number of elements considerably compared with conventional ones using operational amplifiers. As a result, the power dissipation of proposed integrator can be reduced to approximately one-eighth that of conventional integrators. The integrator is applied to a second-order ΔΣ modulator, and its successful operation has been confirmed by transistor-level circuit simulation.

We propose a polarization mode dispersion (PMD) design for high-speed wavelength-division multiplexing (WDM) backbone network systems based on field PMD measurements on installed optical fibers for long-term commercial use. Implementing a high-speed network system on an installed fiber requires measuring PMD, because the PMD characteristics of most installed fibers are unknown. For enhanced practicality, we must be able to precisely evaluate PMD characteristics precisely with just one measurement. To understand the statistical properties of measured PMD values, we use the Jones Matrix Eigenanalysis (JME) method to conduct long-term (12 months) PMD measurements on installed fibers. We statistically analyze the measurement results and confirm that the measured values match the theory that considers the accuracy of the measurement instrument. This enables a PMD design of desired outage probability based on PMD measurements of installed fibers. We also carry out a 43-Gb/s return-to-zero differential quadrature phase shift keying (RZ-DQPSK) signal transmission with high PMD fibers in order to confirm the effectiveness of our PMD design. The PMD values of the in-line amplifier transmission line are settled so as to meet the worst value of the design. We confirm that 43-Gb/s RZ-DQPSK signals are stably transmitted at the design value.

This paper presents a Multiple-Input Multiple-Output (MIMO) propagation model for independent and identically distributed (i.i.d.) channels in the mixture of none-Line-of-Sight (NLOS) and Line-of-Sight (LOS) environments. The derived model enables to evaluate the system statistical characteristics of Signal-to-Noise-Ratio (SNR) for MIMO transmission based on Maximal Ratio Combing (MRC). An application example applying the model in 22 configuration to ITS Inter-Vehicle Communication (IVC) system is introduced. We clarify the effectiveness of the proposed model by comparisons of both computer simulations and measurement results of a field experiment. We also use the model to show the better performance of SNR when applying MIMO to IVC system than SISO and SIMO.

Several kinds of capacitor-less DRAM cells based on planar SOI-MOSFET technology have been proposed and researched to overcome the integration limit of the conventional DRAM. In this paper, we propose the Floating Body type DRAM cell array architecture with the Vertical MOSFET and discuss its basic operation using a 3-D device simulator. In contrast to previous planar SOI-MOSFET technology, the Floating Body type DRAM with the Vertical MOSFET achieves a cell area of 4F2 and obtain its floating body cell by isolating the body from the substrate vertically by the bottom-electrode. Therefore, the necessity for a SOI substrate is eliminated. In this paper, the cell array architecture of Floating Body type 1T-DRAM is proposed, and furthermore, the basic memory operations of read, write, and erase for Vertical type 1 transistor (1T) DRAM in the 45 nm technology node are shown. In addition, the retention and disturb characteristics of the Vertical type 1T-DRAM are discussed.

Multiple antenna is introduced into spectrum sensing in cognitive radios recently. However, conventional multiple antenna spectrum sensing schemes exploited only space diversity. In this paper, we propose a new multiple antenna sensing scheme based on space and time diversity (MASS-BSTD). First, the primary user signal to be sensed is over-sampled at each antenna, and signal samples collected at the same time instant from different antennas are stacked into a column vector. Second, each column vector is utilized to estimate space correlation matrix that exploits space diversity, and two consecutive column vectors are utilized to estimate time correlation matrix that exploits time diversity. Third, the estimated space correlation matrix and time correlation matrix are combined and analyzed using eigenvalue decomposition to reduce information redundancy of signals from multiple antennas. Lastly, the derived eigenvalues are utilized to construct the test statistic and sense the presence of the primary user signal. Since the proposed MASS-BSTD exploits both space diversity and time diversity, it achieves performance gain over the counterparts that only exploit space diversity. Furthermore, the proposed MASS-BSTD requires no prior information on the primary user, the channel between primary user transmitter and secondary user receiver, and is robust to noise uncertainty. Theoretical analysis and simulation results show that the proposed MASS-BSTD can sense the presence of primary user signal reliably.

In this study, we propose a method to reduce the mutual coupling between two J-shaped folded monopole antennas (JFMAs), which cover the IEEE 802.11 b/g (2400-2484 MHz) band. First, the change in mutual coupling with the spacing between the two antenna elements is investigated by considering two feeding models, and the effects of changes in the coupling on the antenna efficiency are studied. Subsequently, we try the method to reduce mutual coupling, the method involves the use of a bridge line that links the two antennas. The mutual coupling can be significantly reduced and the total antenna efficiency can be improved by linking two shorting strips with the bridge line. In a past study, we had found that in the case of L-shaped folded monopole antennas (LFMAs), the mutual coupling and antenna efficiency vary with the linking location on the bridge line. Moreover, we compare the characteristics of the LFMA and JFMA and show that the JFMA is effective when miniaturized.

A fifth-order switched-capacitor (SC) complex filter was implemented in 0.2-µm CMOS technology. A novel SC integrator was developed to reduce the die size and current consumption of the filter. The filter is centered at 24.730.15 kHz (3δ) and has a bandwidth of 20.260.3 kHz (3δ). The image channel is attenuated by more than 42.6 dB. The in-band third-order harmonic input intercept point (IIP3) is 17.3 dBm, and the input referred RMS noise is 34.3 µVrms. The complex filter consumes 350 µA with a 2.0-V power supply. The die size is 0.578 mm2. Owing to the new SC integrator, the filter achieves a 27% reduction in die size without any degradation in its characteristics, including its noise performance, compared with the conventional equivalent.

Gate delay evaluation is always a vital concern for high-performance digital VLSI designs. As the feature size of VLSIs decreases to the nano-meter region, the work to obtain an accurate gate delay value becomes more difficult and time consuming than ever. The conventional methods usually use iterative algorithms to ensure the accuracy of the effective capacitance Ceff, which is usually used to compute the gate delay with interconnect loads and to capture the output signal shape of the real gate response. Accordingly, the efficiency is sacrificed. In this paper, an accurate and efficient approach is proposed for gate delay estimation. With the linear relationship of gate output time points and Ceff, a polynomial approximation is used to make the nonlinear effective capacitance equation be solved without iterative method. Compared to the conventional methods, the proposed method improves the efficiency of gate delay calculation. Meanwhile, experimental results show that the proposed method is in good agreement with SPICE results and the average error is 2.8%.

For the easy design of very small normal-mode helical antennas (NMHAs), an equation that helps determine the self-resonant structures of these antennas is developed. For this purpose, the expression for the capacitance of an NMHA is established. The accuracy of this design equation is confirmed by comparing the results obtained using the equation with the simulation results.