In speech recognition, confidence annotation adopts a single confidence feature or a combination of different features for classification. These confidence features are always extracted from decoding information. However, it is proved that about 30% of knowledge of human speech understanding is mainly derived from high-level information. Thus, how to extract a high-level confidence feature statistically independent of decoding information is worth researching in speech recognition. In this paper, a novel confidence feature extraction algorithm based on latent topic similarity is proposed. Each word topic distribution and context topic distribution in one recognition result is firstly obtained using the latent Dirichlet allocation (LDA) topic model, and then, the proposed word confidence feature is extracted by determining the similarities between these two topic distributions. The experiments show that the proposed feature increases the number of information sources of confidence features with a good information complementary effect and can effectively improve the performance of confidence annotation combined with confidence features from decoding information.

In this letter, we propose three algorithms to reduce congestion for greedy forwarding, which is one of common principles in geographic routing. The new algorithms take geographic position information and network congestion metrics to balance traffic. When these algorithms are combined with well-known GPSR protocol [1], packet delivery ratio is enhanced by reducing number of lost packets in a buffer. In addition, end-to-end delay is reduced by bypassing congested nodes. These features are evaluated and analyzed through several simulation results.

This paper proposes an efficient adaptive depth-map coding scheme for generating virtual-view images in 3D-video. Virtual-view images can be generated by view-interpolation based on the decoded depth-map of the image. The proposed depth-map coding scheme is designed to have a new gray-coding-based bit-plane coding method for efficiently coding the depth-map images on the object-boundary areas, as well as the conventional DCT-based coding scheme (H.264/AVC) for efficiently coding the inside area images of the objects or the background depth-map images. Simulation results show that the proposed coding scheme, in comparison with the H.264/AVC coding scheme, improves the BD-rate savings 6.77%-10.28% and the BD-PSNR gains 0.42 dB-0.68 dB. It also improves the subjective picture quality of synthesized virtual-view images using decoded depth-maps.

This paper presents a Pulse-Width Modulation (PWM) pre-emphasis technique which utilizes time-domain information processing to increase the data rate for a given bandwidth of interconnection. The PWM pre-emphasis method does not change the pulse amplitude as for conventional FIR pre-emphasis, but instead exploits timing resolution. This fits well with recent CMOS technology trends toward higher switching speeds and lower supply voltage. We discuss multiple-valued data transmission based on time-domain pre-emphasis techniques in consideration of higher-order channel effects. Also, a new data-dependent adaptive time-domain pre-emphasis technique is proposed to compensate for the data-dependent jitter.

This paper proposes an interference avoidance technique that allows wireless device with similar frequency bands to be operated adjacent to each other for compact mobile wireless routers (MWRs). This MWR implements two devices of Wireless LAN (WLAN) and Worldwide Interoperability for Microwave Access (WiMAX). The MWR connects WLAN terminals to the backbone network by using WiMAX-WLAN relay. Generally, different frequency channels are assigned for the wireless systems assign in order not to interfere among multiple systems. However, mutual system interference is generated if the space between each device is very close and if the frequency using each system is adjacent. To suppress this interference, this paper proposes a novel interference avoidance technique that leverages IEEE802.11n Power Save Multi-Poll (PSMP). First, we clarify the conditions that raise the issues of mutual interference by experiment. Simulations are conducted to show that the proposed scheme outperforms the conventional schemes. Finally, the effectiveness of the proposed scheme is shown by the computer simulation.

In this paper, a coexistence mechanism between IEEE 802.15.4 and IEEE 802.11b, Active Channel Reservation for cOexiStence (ACROS), is proposed. The key idea underlining ACROS is to reserve the channel for IEEE 802.15.4 transmission, where IEEE 802.11 transmissions are forbidden. The request-to-send (RTS)/clear-to send (CTS) mechanism within IEEE 802.11 is used to reserve a channel. The proposed ACROS mechanism is implemented into a PC based prototype. The embedded version of ACROS is also developed to mitigate the timing drift problem in the PC-based ACROS. The efficiency of ACROS is shown using the throughput and packet error rate achieved in actual experiments.

A monolithic modulator driver IC based on InP HBTs with a new circuit topology -- called a functional distributed circuit (FDC) -- for over 80-Gb/s optical transmission systems has been developed. The FDC topology includes a wide-band amplifier designed using a distributed circuit, a digital function designed using a lumped circuit, and broadband impedance matching between the lumped circuit and distributed circuit to enable both wider bandwidth and digital functions. The driver IC integrated with a 2:1 multiplexing function produces 2.6-Vp-p (differential output: 5.2 Vp-p) and 2.4- Vp-p (differential output: 4.8 Vp-p) output-voltage swings with less than 450-fs and 530-fs rms jitter at 80 Gb/s and 90 Gb/s, respectively. To the best of our knowledge, this is equivalent to the highest data rate operation yet reported for monolithic modulator drivers. When it was mounted in a module, the driver IC successfully achieved electro-optical modulation using a dual-drive LiNbO3 Mach-Zehnder modulator up to 90 Gb/s. These results indicate that the FDC has the potential to realize high-speed and functional ICs for over-80-Gb/s transmission systems.

This paper proposes and investigates a distributed adaptive contention window adjustment algorithm based on the transmission history for wireless LANs called the transmission-history-based distributed adaptive contention window adjustment (THAW) algorithm. The objective of this paper is to reduce the transmission delay and improve the channel throughput compared to conventional algorithms. The feature of THAW is that it adaptively adjusts the initial contention window (CWinit) size in the binary exponential backoff (BEB) algorithm used in the IEEE 802.11 standard according to the transmission history and the automatic rate fallback (ARF) algorithm, which is the most basic algorithm in automatic rate controls. This effect is to keep CWinit at a high value in a congested state. Simulation results show that the THAW algorithm outperforms the conventional algorithms in terms of the channel throughput and delay, even if the timer in the ARF is changed.

The success of peer-to-peer overlay networks depends on cooperation among participating peers. In this paper, we investigate the degree of cooperation among individual peers required to induce globally favorable properties in an overlay network. Specifically, we consider a resource pricing problem in a market-oriented overlay network where participating peers sell own resources (e.g., CPU cycles) to earn energy which represents some money or rewards in the network. In the resource pricing model presented in this paper, each peer sets the price for own resource based on the degree of cooperation; non-cooperative peers attempt to maximize their own energy gains, while cooperative peers maximize the sum of own and neighbors' energy gains. Simulation results are presented to demonstrate that the network topology is an important factor influencing the minimum degree of cooperation required to increase the network-wide global energy gain.

The purpose of this paper is to propose an efficient and effective design scheme to implement compact, high-performance wideband bandpass filters based on a novel compound three-line unit consisting of a stub-loaded short-circuited parallel-coupled three-line structure and two lead lines. Firstly, a simulative investigation is conducted on the transmission characteristics of the proposed coupling unit. The results show that the bandwidth of such structure can be predicted by a symmetric parallel-coupled short-circuited three-line unit, whereas the transmission zeros by a three-section stub composed of the loaded stub, one of the parallel-coupled three lines and the lead line. Accordingly, given specifications, a pseudo-elliptical filter can be designed in an novel three-coupled-line based two-step design scheme: 1. after the derivation of the new closed-form synthesis formulae, a Chebyshev ultra-wideband (UWB) filter is synthesized on a desired passband using symmetric three-line coupling units. 2. By designing the stubs and choosing the proper lengths of the lead lines, multiple transmission zeros are then introduced to improve the skirt and stopband characteristics, whereas the equiripple characteristics are kept in passband. As an example, a UWB bandpass filter covering the Japan's lower UWB band (BW: 3.1-4.8 GHz, FBW: 43%) is designed to describe the proposed design procedure. The measured filtering characteristics agree very well with the theoretical predictions, which validate the effectiveness of the proposed new coupling structure and corresponding filter design technique. In addition, the designed filters exhibit good characteristics, such as steep skirt selectivity, very wide stopbands, a compact size compared with the filter based on short-circuited three-line structure, etc.

A post-wall center-feed waveguide consisting of T-junctions is proposed for reducing the slot-free area of a parallel plate slot array antenna. The width of the slot-free area is reduced from 2.6 λ0 to 2.1 λ0. A sidelobe level in the E-plane is expected to be suppressed lower than that of the conventional center-feed antenna using cross-junctions. The method of moments with solid-wall replacement designs initially the T-junctions and HFSS including the post surfaces modifies only the reflection cancelling post. We have designed and fabricated a 61.25 GHz model antenna with uniform aperture illumination. The sidelobe level in the E-plane is suppressed to -9.5 dB while that of a conventional cross-junction type is -7.8 dB. Also, we suppress it to -13.8 dB by introducing a -8.3 dB amplitude tapered distribution in the array of the radiation slot pairs.

Beam steering of leaky wave radiation from a nonreciprocal composite right/left handed transmission line with a ferrite substrate is proposed. The nonreciprocal phase constants of the line were tuned by changing the applied DC magnetic field normal to the ferrite substrate. In the numerical simulation and the experiment, the nonreciprocal phase characteristics and leaky wave radiation are investigated for the ferrite substrate with the magnetization not only in the saturated region, but also in the unsaturated region. The numerical simulation results are in good agreement with the measurement. It is confirmed that the beam directions of the obliquely unidirectional leaky wave radiation for two different power directions are continuously tunable.

Passive optical network topology has been widely adopted in access networks due to its low-cost and yet flexible network structure. To further promote the passive optical networks, the cost reduction of optical modules is critical. Relatively expensive combination of a conventional index-coupled distributed feedback laser diode (IC-DFB-LD) and an optical isolator is commonly used for passive optical networks with transmission distance more than 30 km. Although gain-coupled DFB-LDs (GC-DFB-LD) have been widely investigated in the hope of eliminating the isolator in optical modules, their limited output power keeps them from practical use in passive optical networks. In this paper, we describe the development of 1.31 µm and 1.49 µm GC-DFB-LDs with high output power and optical feed back tolerance for isolator-free optical modules in access networks. The relative intensity noise (RIN) degradation was well suppressed below -120 dB/Hz at -8 dB optical feedback in the temperatures range from 0 to 85 from both 1.31 µm and 1.49 µm GC-DFB-LDs. Optical feedback tolerance of 1.31 µm and 1.49 µm GC-DFB-LDs were improved by more than 6 dB and 4 dB as compared with conventional IC-DFB-LDs. Dispersion power penalty after over 30 km transmission at 1.25 Gbps were achieved less than 0.3 dB and 0.7 dB under -15 dB optical feedback conditions. The proposed 1.31 µm GC-DFB-LD prototypes experimentally demonstrated 14 mW output power with over 5,000-hour operation at 85. Our devices are found to fully complying IEEE 802.3ah standard and seem to be promising for the low-cost optical modules in long-reach access network applications. The details of the device structure as well as transmission experiments are also reported.

Newly developed multi-layer inductors on GaAs three-dimensional MMICs are presented. We analyzed single-, double-, triple-, and quadruple-layer stacked-type inductors in what may be the first report on inductors on a GaAs MMIC with three or more layers. The performance of single- and multi-layer inductors was measured and calculated by electromagnetic field simulation. The multi-layer inductors produce 2-11 times higher inductance than that of conventional inductors on 2D-MMICs although they are the same size. This means that the proposed multi-layer inductors have smaller areas with the same inductances than those of conventional inductors. We also conducted the first-ever investigation of how performance factors such as parasitic capacitance, Q-factor, and self-resonant frequency are degraded in multi-layer inductors vis-a-vis those of conventional inductors. A microwave amplifier using multi-layer inductors was demonstrated and found to reduce circuit size by 20%.

Numerical simulations of the gain and phase center measurements for a pyramidal horn antenna are carried out. The electromagnetic simulation is based on the finite integration method. The gain of horn antennas varies with the distance between their apertures, even if the antennas satisfy the far-field criterion. This gain variation is shown to correspond with the ratio of the distance between the apertures to the distance between the phase centers. The experimental results also demonstrate the efficacy of considering the location of the phase center for antenna calibration.

This paper presents a high-speed, low-complexity VLSI architecture based on the modified Euclidean (ME) algorithm for Reed-Solomon decoders. The low-complexity feature of the proposed architecture is obtained by reformulating the error locator and error evaluator polynomials to remove redundant information in the ME algorithm proposed by Truong. This increases the hardware utilization of the processing elements used to solve the key equation and reduces hardware by 30.4%. The proposed architecture retains the high-speed feature of Truong's ME algorithm with a reduced latency, achieved by changing the initial settings of the design. Analytical results show that the proposed architecture has the smallest critical path delay, latency, and area-time complexity in comparison with similar studies. An example RS(255,239) decoder design, implemented using the TSMC 0.18 µm process, can reach a throughput rate of 3 Gbps at an operating frequency of 375 MHz and with a total gate count of 27,271.

This letter proposes a novel design approach for optimal contourlet filter banks based on the parametric 9/7 filter family. The Laplacian pyramid decomposition is replaced by optimal 9/7 filter banks with rational coefficients, and directional filter banks are activated using a pkva 12 filter in the contourlets. Moreover, based on this optimal 9/7 filter, we present an image denoising approach using a contourlet domain hidden Markov tree model. Finally, experimental results show that our approach in denoising images with texture detail is only 0.20 dB less compared to the method of Po and Do, and the visual quality is as good as for their method. Compared with the method of Po and Do, our approach has lower computational complexity and is more suitable for VLSI hardware implementation.

Noise coupling on the power distribution networks (PDN) or between PDN and signal traces is becoming one of the main challenges in designing above GHz high-speed digital circuits. Developing an efficient and accurate modeling method is essential to understand the noise coupling mechanism and then solve the problem afterwards. In addition, development of new noise mitigation technology is also important for future high-speed circuit systems. In this invited paper, a novel modeling methodology that is based on the physics-based equivalent circuit model will be introduced, and an example of multiple layer PCB circuits will be modeled and validated with good accuracy. Based on the periodic structure concept, several new electromagnetic bandgap structures (EBG), such as coplanar EBG, photonic crystal power layer (PCPL), and ground surface perturbation lattice (GSPL), will be introduced for the mitigation of power/ground noise. The trade/offs of all these structures will be discussed.

This paper presents a novel algorithm for Nearest Neighbor (NN) classifier. NN classification is a well-known method of pattern classification having the following properties: * it performs maximum-margin classification and achieves less than twice the ideal Bayesian error, * it does not require knowledge of pattern distributions, kernel functions or base classifiers, and * it can naturally be applied to multiclass classification problems. Among the drawbacks are A) inefficient memory use and B) ineffective pattern classification speed. This paper deals with the problems A and B. In most cases, NN search algorithms, such as k-d tree, are employed as a pattern search engine of the NN classifier. However, NN classification does not always require the NN search. Based on this idea, we propose a novel algorithm named k-d decision tree (KDDT). Since KDDT uses Voronoi-condensed prototypes, it consumes less memory than naive NN classifiers. We have confirmed that KDDT is much faster than NN search-based classifier through a comparative experiment (from 9 to 369 times faster than NN search based classifier). Furthermore, in order to extend applicability of the KDDT algorithm to high-dimensional NN classification, we modified it by incorporating Gabriel editing or RNG editing instead of Voronoi condensing. Through experiments using simulated and real data, we have confirmed the modified KDDT algorithms are superior to the original one.

We have so far proposed a speaking-aid system for laryngectomees using a statistical voice conversion technique. In the proposed system, artificial speech articulated with extremely small sound source signals is detected with a Non-Audible Murmur (NAM) microphone, and then, the detected artificial speech is converted into more natural voice in a probabilistic manner. Although this system basically allows laryngectomees to speak while keeping the external source signals silent, it is still questionable how much these new sound source signals affect the converted speech quality. In this paper, we investigate the impact of various sound source signals on voice conversion accuracy. Various small sound source signals are designed by changing the spectral envelope and the waveform power independently. We conduct objective and subjective evaluations. The results of these experimental evaluations demonstrate that voice conversion accepts 1) various sound source signals with different spectral envelopes and 2) large degree of power of the sound source signals unless the power of speaking parts is almost equal to that of silence parts. Moreover, we also investigate the effectiveness of enhancing auditory feedback during speaking with the extremely small sound source signals.