A vocoder-based speech synthesis system, named WORLD, was developed in an effort to improve the sound quality of real-time applications using speech. Speech analysis, manipulation, and synthesis on the basis of vocoders are used in various kinds of speech research. Although several high-quality speech synthesis systems have been developed, real-time processing has been difficult with them because of their high computational costs. This new speech synthesis system has not only sound quality but also quick processing. It consists of three analysis algorithms and one synthesis algorithm proposed in our previous research. The effectiveness of the system was evaluated by comparing its output with against natural speech including consonants. Its processing speed was also compared with those of conventional systems. The results showed that WORLD was superior to the other systems in terms of both sound quality and processing speed. In particular, it was over ten times faster than the conventional systems, and the real time factor (RTF) indicated that it was fast enough for real-time processing.

Reconfigurable architectures have emerged as an optimal choice for the hardware realization of digital signal processing (DSP) algorithms. Reconfigurable architecture is either fine-grained or coarse-grained depending on the granularity of reconfiguration used. The flexibility offered by fine-grained devices such as field programmable gate array (FPGA) comes at a significant cost of huge routing area, power consumption and speed overheads. To overcome these issues, several coarse-grained reconfigurable architectures have been proposed. In this paper, a scalable and hybrid dynamically reconfigurable architecture, HyDRA, is proposed for efficient hardware realization of computation intensive DSP algorithms. The proposed architecture is greatly influenced by reported VLSI architectures of a variety of DSP algorithms. It is designed using parameterized VHDL model which allows experimenting with a variety of design features by simply modifying some constants. The proposed architecture with 8×8 processing element array is synthesized using UMC 0.25µm and LF 150nm CMOS technologies respectively. For quantitative evaluation, the architecture is also realized using Xilinx Virtex-7 FPGA. The area and timing results are presented to provide an estimate of each block of the architecture. DSP algorithms such as 32-tap finite impulse response (FIR) filters, 16-point radix-2 single path delay feedback (R2SDF) fast fourier transform (FFT) and R2SDF discrete cosine transform (DCT) are mapped and routed on the proposed architecture.

Radar cross section (RCS) of a patch array antenna is reduced using a switchable absorption/transmission surface. The switchable surface performs as between a radar absorber and transmission surface using diodes at 9GHz. The switchable surface was applied to the radome of a patch array and its radiation pattern and RCS reduction were evaluated. The gain and the radiation pattern with the radome was equivalent to that without the radome. The RCS reduction with the radome was 25dB compared to that without the radome.

To provide basic considerations for the realization of method for suppressing the EMI from differential-paired lines on flexible printed circuits (FPC), the characteristics of the SI performance and shielding effectiveness (SE) of shielded-flexible printed circuits for differential-signaling are investigated in this paper experimentally and by a numerical modeling. Firstly, transmission characteristics of TDR measurement and frequency response of |Sdd21| are discussed, from view point of signal integrity. Secondly, as the characteristics of the SE performance for EMI, frequency responses of magnetic field are investigated. Although placement of conductive shield near the paired-lines decreases characteristics impedance, |Sdd21| for the “with Cu 5.5 µm-thickness copper shield” is not deteriorated compared with “without shield” and sufficient SE performance for magnetic field can be established. But, thin-shield deteriorates SI as well as SE performances. The frequency response of |Sdd21| at higher frequencies for the “Ag 0.1 µm” case has the steep loss roll off. A reflection loss resulted from impedance-mismatching is not dominant factor of the losses. The dominant factor may be magnetic field leakage due to very thin-conductive shield.

This paper presents a new approach for circuit matching using signatures. We have defined a signature based on topology of the fanin cones of the circuit elements. Given two circuits, first we find all the circuit elements with unique signature between the two input circuits. After that, we try to expand the matching area by our expansion rules as much as possible. We iteratively find the unique matches and expand the matching area until no further matching is possible. Our experiments on IWLS2005 benchmark suite show that our method is able to find the perfect matching between two 160,000-gate IP in 5 minutes. In addition, our method is more than one order of magnitude faster than our previous signature-based matching method, while the size of the matched area is comparable or larger.

In this paper, we propose an infrastructure-free precise positioning system by utilizing a variation of received radio broadcast signal strength against vehicle travel as fingerprints of road segments. Use of broadcast wave is considered advantageous in deployment cost and sample density that affects measurement reliability, compared to communication medium such as 802.11p-based V2X radio used in our previous paper. We also present preliminary experimental results that indicate potential of positioning at 20cm accuracy by using reception information of two FM radio channels broadcast from a station about 20km away from the test track

We present a rebound attack on the 4-branch type-2 generalized Feistel structure with an SPS round function, which is called the type-2 GFN-SPS in this paper. Applying a non-full-active-match technique, we construct a 6-round known-key truncated differential distinguisher, and it can deduce a near-collision attack on compression functions of this structure embedding the MMO or MP modes. Extending the 6-round attack, we build a 7-round truncated differential path to get a known-key differential distinguisher with seven rounds. The results give some evidences that this structure is not stronger than the type-2 GFN with an SP round function and not weaker than that with an SPSP round function against the rebound attack.

Recently, multi-user multiple-input multiple-output (MU-MIMO) systems are being widely studied. For interference cancellation, MU-MIMO commonly uses spatial precoding techniques. These techniques, however, require the transmitters to have perfect knowledge of the downlink channel state information (CSI), which is hard to achieve in high mobility environments. Instead of spatial precoding, a collaborative interference cancellation (CIC) technique can be implemented for these environments. In CIC, mobile stations (MSs) collaborate and share their received signals to increase the demultiplexing capabilities. To obtain efficient signal-exchange between collaborating users, signal selection can be implemented. In this paper, a signal selection scheme suitable for a QRM-MLD algorithm is proposed. The proposed scheme uses the minimum Euclidean distance criterion to obtain an optimum bit error rate (BER) performance. Numerical results obtained through computer simulations show that the proposed scheme is able to provide BER performance near to that of MLD even when the number of candidates in QRM-MLD is relatively small. In addition, the proposed scheme is feasible to implement owing to its low computational complexity.

A novel computational method based on a combination of the method of moments in the complex frequency domain and the fast inverse Laplace transform is proposed for solving time-domain electromagnetic problems. Using our proposed method, it is easy to estimate and control the computational error, and the observation time can be selected independently. We investigate canonical scattering problems and verify these advantages.

Transfer learning extracts useful information from the related source domain and leverages it to promote the target learning. The effectiveness of the transfer was affected by the relationship among domains. In this paper, a novel multi-source transfer learning based on multi-similarity was proposed. The method could increase the chance of finding the sources closely related to the target to reduce the “negative transfer” and also import more knowledge from multiple sources for the target learning. The method explored the relationship between the sources and the target by multi-similarity metric. Then, the knowledge of the sources was transferred to the target based on the smoothness assumption, which enforced that the target classifier shares similar decision values with the relevant source classifiers on the unlabeled target samples. Experimental results demonstrate that the proposed method can more effectively enhance the learning performance.

In interactive audio services, users can render audio objects rather freely to match their desires and the spatial audio object coding (SAOC) scheme is fairly good both in the sense of bitrate and audio quality. But rather perceptible audio quality degradation can occur when an object is suppressed or played alone. To complement this, the SAOC scheme with Two-Step Coding (SAOC-TSC) was proposed. But the bitrate of the side information increases two times compared to that of the original SAOC due to the bitrate needed for the residual coding used to enhance the audio quality. In this paper, an efficient residual coding method of the SAOC-TSC is proposed to reduce the side information bitrate without audio quality degradation or complexity increase.

As semiconductor technologies have advanced, the reliability problem caused by soft-errors is becoming one of the serious issues in LSIs. Moreover, multiple component errors due to single soft-errors also have become a serious problem. In this paper, we propose a method to synthesize multiple component soft-error tolerant application-specific datapaths via high-level synthesis. The novel feature of our method is speculative resource sharing between the retry parts and the secondary parts for time overhead mitigation. A scheduling algorithm using a special priority function to maximize speculative resource sharing is also an important feature of this study. Our approach can reduce the latency (schedule length) in many applications without deterioration of reliability and chip area compared with conventional datapaths without speculative resource sharing. We also found that our method is more effective when a computation algorithm possesses higher parallelism and a smaller number of resources is available.

This paper describes two speed-up techniques for Boolean matching of LUT-based circuits. One is one-hot encoding technique for variables representing input assignments. Though it requires more variables than existing binary encoding technique, almost all added clauses using one-hot encoding are binary clauses, which are suitable for efficient Boolean constraint propagation. The other is CEGAR (counter example guided abstraction refinement) technique which reduces the CPU time significantly. With both techniques, we can solve Boolean matching problem with 9 input function in 20 milliseconds on average, which is faster than the existing algorithms more than one order of magnitude.

Ternary content addressable memory (TCAM), which can store 0, 1, or X in its cells, is widely used to store routing tables in network routers. Negative bias temperature instability (NBTI) and positive bias temperature instability (PBTI), which increase Vth and degrade transistor switching speed, have become major reliability challenges. This study analyzes the signal probability of routing tables. The results show that many cells retain static stress and suffer significant degradation caused by NBTI and PBTI effects. The bit flipping technique is improved and proactive power gating recovery is proposed to mitigate NBTI and PBTI effects. In order to maintain the functionality of TCAM after bit flipping, a novel TCAM cell design is proposed. Simulation results show that compared to the original architecture, the bit flipping technique improves read static noise margin (SNM) for data and mask cells by 16.84% and 29.94%, respectively, and reduces search time degradation by 12.95%. The power gating technique improves read SNM for data and mask cells by 12.31% and 20.92%, respectively, and reduces search time degradation by 17.57%. When both techniques are used, read SNM for data and mask cells is improved by 17.74% and 30.53%, respectively, and search time degradation is reduced by 21.01%.

This paper describes, for the first time, the circuit design considerations and measurements of core building blocks that support a 1.9-GHz-band (Band I) BiFET MMIC three-power-mode power amplifier (PA) for WCDMA handset applications. The blocks are a reference voltage (Vref) generator, a control logic circuit, and ESD protection circuits. Our proposed Vref-generator, based on a current-mirror topology, can successfully suppress Vref variation against threshold voltage (Vth) dispersion in the FET as well as current gain dispersion in the HBT. On-wafer measurements over several wafer lots show that the standard deviation of Vref is as small as 18 mV over a Vth dispersion range from -0.6 V to -1.0 V. As a result, the measured quiescent current dispersion in the HPM is also suppressed to less than 5.4 mA, despite the fact that the average quiescent current is relatively high, at 81.3 mA. Several simulations reveal that small decoupling capacitances of approximately 1 pF added to the gate control lines of RF switch FETs ensure stable operation of the control logic even if an undesired RF coupling is present between an RF signal path and the gate lines. An empirical and useful design approach for ESD protection using HBT base-collector diodes allows easy and precise estimation of the HBM ESD robustness. With the above building blocks, a 3 mm × 3 mm PA was designed and fabricated by an in-house BiFET process. Measurements conducted under the conditions of a 3.4-V supply voltage and a 1.95-GHz WCDMA modulated signal are as follows. The PA delivers a 28.3-dBm output power (Pout), a 28.2-dB power gain (Gp), and 40% PAE while restricting the ACLR1 to less than -42 dBc in the HPM. In the MPM, 17.4 dBm of Pout, 15.9 dB of Gp, and 25.3% of PAE are obtained, while in the LPM, the PA delivers 7 dBm of Pout, 11.7 dB of Gp, and 13.9% of PAE. The HBM ESD robustness is 2 kV.

With the increase of network components connected to the Internet, the need to ensure secure connectivity is becoming increasingly vital. Intrusion Detection Systems (IDSs) are one of the common security components that identify security violations. This paper proposes a novel multilevel hybrid classifier that uses different feature sets on each classifier. It presents the Discernibility Function based Feature Selection method and two classifiers involving multilayer perceptron (MLP) and decision tree (C4.5). Experiments are conducted on the KDD'99 Cup and ISCX datasets, and the proposal demonstrates better performance than individual classifiers and other proposed hybrid classifiers. The proposed method provides significant improvement in the detection rates of attack classes and Cost Per Example (CPE) which was the primary evaluation method in the KDD'99 Cup competition.

The current high efficiency video coding (HEVC) standard is developed to achieve greatly improved compression performance compared with the previous coding standard H.264/AVC. It adopts a quadtree based picture partition structure to flexibility signal various texture characteristics of images. However, this results in a dramatic increase in computational complexity, which obstructs HEVC in real-time application. To alleviate this problem, we propose a fast coding unit (CU) size decision algorithm in HEVC intra coding based on consideration of the depth level of neighboring CUs, distribution of rate distortion (RD) value and distribution of residual data. Experimental results demonstrate that the proposed algorithm can achieve up to 60% time reduction with negligible RD performance loss.

As the semiconductor technology continues to develop, hundreds of cores will be deployed on a single die in the future Chip-Multiprocessors (CMPs) design. Three-Dimensional Network-on-Chips (3D NoCs) has become an attractive solution which can provide impressive high performance. An efficient and deadlock-free routing algorithm is a critical to achieve the high performance of network-on-chip. Traditional methods based on deterministic and turn model are deadlock-free, but they are unable to distribute the traffic loads over the network. In this paper, we propose an efficient, adaptive and deadlock-free algorithm (EAR) based on a novel routing selection strategy in 3D NoC, which can distribute the traffic loads not only in intra-layers but also in inter-layers according to congestion information and path diversity. Simulation results show that the proposed method achieves the significant performance improvement compared with others.

The finite-difference time-domain (FDTD) method has been widely used in recent years to analyze the propagation and scattering of electromagnetic waves. Because the FDTD method has second-order accuracy in space, its numerical dispersion error arises from truncated higher-order terms of the Taylor expansion. This error increases with the propagation distance in cases of large-scale analysis. The numerical dispersion error is expressed by a dispersion relation equation. It is difficult to solve this nonlinear equation which have many parameters. Consequently, a simple formula is necessary to substitute for the dispersion relation error. In this study, we have obtained a simple formula for the numerical dispersion error of 2-D and 3-D FDTD method in free space propagation.

This paper investigates a frame aggregation (FA) technique in the medium access control (MAC) layer for downlink multi-user multiple input multiple output (MU-MIMO) channels in wireless local area networks (WLANs), and proposes a high-efficient FA scheme that ehances system performance: transmission performance and fairness in communication between mobile terminals (MTs). The proposed FA scheme employs novel criteria for selecting receiving MTs and wireless frame setting with a frame size adaptation mechanism for MU-MIMO transmissions. The proposed receiving MT selection gives higher priority to the MTs expecting higher throughput in the next MU-MIMO transmission and having large amount transmission data while reducing signaling overhead, leading to improvements in system throughput and fairness in communication. The proposed wireless frame setting, which employs hybrid A-MSDU/A-MPDU FA, achieves frame error rate (FER) better than the requirement from communication services by using A-MSDU frame size adaptation. Through system-level simulation, the effectiveness of the proposed scheme is validated for downlink MU-MIMO channels in WLANs.