We propose Max-Plus Linear (MPL) systems with selective parameters that can describe a certain class of Timed Petri nets (TPN). In this class, selector and joint places are incorporated with Single-Input and Single-Output Timed Event Graph (SISO TEG) subnets. We confirm that the proposed controller effectively works taking into account practical constraints through a numerical example.

Environment measurement is an important issue for various applications including household robots. Pulse radars are promising candidates in a near future. Estimating target shapes using waveform data, which we obtain by scanning an omni-directional antenna, is known as one of ill-posed inverse problems. Parametric methods such as Model-fitting method have problems concerning calculation time and stability. We propose a non-parametric algorithm for high-resolution estimation of target shapes in order to solve the problems of parametric algorithms.

Illegal distribution of signed documents can be considered as one of serious problems of digital signatures. In this paper, to solve the problem, we propose three protocols concerning signature schemes. These schemes achieve not only traceability of an illegal user but also universal verifiability. The first scheme is a basic scheme which can trace an illegal receiver, and the generation and tracing of a signed document are simple and efficient. However, in this scheme, it is assumed that a signer is honest. The second scheme gives another tracing method which does not always assume that a signer is honest. Furthermore, in the method, an illegal user can be traced by an authority itself, hence, it is efficient in terms of communication costs. However, in this scheme it is assumed that there exists only a legal verification algorithm. Thus, in general, this scheme cannot trace a modified signed document which is accepted by a modified verification algorithm. The third one is a scheme which requires no trusted signer and allows a modified verification algorithm. It can trace an illegal receiver or even a signer in such a situation. All of our schemes are constructed by simple combinations of standard signature schemes, consequently, one can flexibly choose suitable building blocks for satisfying requirements for a system.

In distant-talking speech recognition, the recognition accuracy is seriously degraded by reverberation and environmental noise. A robust speech recognition technique in such environments, HMM separation and composition, has been described in. HMM separation estimates the model parameters of the acoustic transfer function using adaptation data uttered from an unknown position in noisy and reverberant environments, and HMM composition builds an HMM of noisy and reverberant speech, using the acoustic transfer function estimated by HMM separation. Previously, HMM separation has been applied to the acoustic transfer function based on a single Gaussian distribution. However the improvement was smaller than expected for the impulse response with long reverberations. This is because the variance of the acoustic transfer function in each frame increases, since the length of the impulse response of the room reverberation is longer than that of the spectral analysis window. In this paper, HMM separation is extended to estimate the acoustic transfer function based on the Gaussian mixture components in order to compensate for the greater variability of the acoustic transfer function, and the re-estimation formulae are derived. In addition, this paper introduces a technique to adapt the noise weight for each mel-spaced frequency in order to improve the performance of the HMM separation in the linear-spectral domain, since the use of the HMM separation in the linear-spectral domain sometimes causes a negative mean output due to the subtraction operation. The extended HMM separation is evaluated on distant-talking speech recognition tasks. The results of the experiments clarify the effectiveness of the proposed method.

This letter evaluates the peak-to-average power ratio (PAR) performance in a space-time block coded (STBC) multicode CDMA (MC-CDMA) system using a selected mapping (SLM) approach. The ordinary method is to apply the SLM scheme for each transmit antenna individually, while the investigated SLM-based STBC MC-CDMA system selects the transmitted sequence with the lowest average PAR over all transmit antennas concurrently. SLM-based STBC MC-CDMA system retrieves the side information very accurately at the expense of a slight degradation of the PAR performance, which can improve the overall detection performance of the STBC MC-CDMA system in the presence of erroneous side information compared to the ordinary SLM approach.

In wireless communication systems where users compete for limited bandwidth, radio resource control is essential for throughput enhancement and delay reduction. In this paper, we present a game-theoretical approach to distributed resource control in CDMA systems. Incomplete information about channel conditions is considered. The resource control problem is formulated as a noncooperative game of incomplete information, with which the existence and uniqueness of the Bayesian Nash equilibrium (BNE) of the game is investigated. Since the equilibrium is Pareto inefficient, we propose a pricing policy to the resource control game by adding a penalty price to user's transmission cost. With the adoption of the price, user's aggressive behavior is depressed, and Pareto improvement is achieved. Also the Pareto efficient BNE of the game with pricing is studied. Simulation results show that users can obtain higher throughput and lower average packet transmission delay by proper pricing policy. It is also verified that the scheme of pricing policy is robust when information of channel conditions is inaccurate.

The model for the process of F0 contour generation, first proposed by Fujisaki and his coworkers, has been successfully applied to Standard Chinese, which is a typical tone language with a distinct feature that both positive and negative tone commands are required. However, the inverse problem, viz., automatic derivation of the model parameters from an observed F0 contour of speech, cannot be solved analytically. Moreover, the extraction of model parameters for Standard Chinese is more difficult than for Japanese and English, because the polarity of tone commands cannot be inferred directly from the F0 contour itself. In this paper, an efficient method is proposed to solve the problem by using information on syllable timing and tone labels. With the same framework as for the successive approximation method proposed for Japanese and English, the method presented here for Standard Chinese is focused on the first-order estimation of tone command parameters. A set of intra-syllable and inter-syllable rules are constructed to recognize the tone command patterns within each syllable. The experiment shows that the method works effectively and gives results comparable to those obtained by manual analysis.

Recently, low-density parity-check (LDPC) codes have attracted much attention. LDPC codes can achieve the near Shannon limit performance like turbo codes. For the LDPC codes, the reduced complexity decoding algorithms referred to as uniformly most powerful (UMP) BP- and normalized BP-based algorithms were proposed for BPSK on an additive white Gaussian noise (AWGN) channel. The conventional BP and BP-based algorithms can be applied to BPSK modulation. For high bit-rate transmission, multilevel modulation is preferred. Thus, the BP algorithm for multilevel modulations is proposed in . In this paper, we propose the BP algorithm with reduced complexity for multilevel modulations, where the first likelihood of the proposed BP algorithm is modified to adjust multilevel modulations. We compare the error rate performance of the proposed algorithm with that of the conventional algorithm on AWGN and flat Rayleigh fading channels. We also propose the UMP BP- and normalized BP-based algorithms for multilevel modulations on AWGN and flat Rayleigh fading channels. We show that the error rate performance of the proposed BP algorithm is almost identical to that of the algorithm in, where the decoding complexity of the proposed BP algorithm is less than that of the algorithm in. We also show that the proposed BP-based algorithms can achieve the good trade-off between the complexity and the error rate performance.

We apply a selective-sets resizable cache and a complete hierarchy SRAM for the high-performance and low-power RISC CPU core. The selective-sets resizable cache can change the cache memory size by varying the number of cache sets. It reduces the leakage current by 23% with slight degradation of the worst case operating speed from 213 MHz to 210 MHz. The complete hierarchy SRAM enables the partial swing operation not only in the bit lines, but also in the global signal lines. It reduces the current consumption of the memory by 4.6%, and attains the high-speed access of 1.4 ns in the typical case.

We proposed a push-pull output buffer that maintains the data transmission rate for lower supply voltages. It operates at an internal supply voltage (VDD) of 0.7-1.6 V and an interface supply voltage (VDDX) of 1.0-3.6 V. In low VDDX operation, the output buffer utilizes parasitic bipolar transistors instead of MOS transistors to maintain drivability. Furthermore forward body bias (FBB) control is provided for the level converter in low VDD operation. We fabricated a test chip with a standard 0.15 µm CMOS process. Measurement results indicate that the proposed output buffer achieves 200 Mbps operation at VDD of 0.7 V and VDDX of 1.0 V.

This paper describes the design and implementation of a testbed for predicting master/slave (M/S) programs written using Message Passing Interface (MPI) programs. The testbed, named M/S Emulator (MSE), aims at assisting developers in evaluating the performance of M/S programs and dynamic load-balancing strategies on clusters of PCs. In order to realize this, MSE predicts the communication time by using a realistic parallel computational model, an extension of the LogGPS model. This extended model improves the prediction accuracy on a large number of processors, because it captures the master's bottleneck: the overhead required for retrieving arrival messages from the slaves. Current MSE also employs a best effort emulation method for predicting the calculation time. In our experiments, MSE demonstrated an accurate prediction on clusters, especially on a larger number of nodes. Therefore, we believe that our extended model enables us to analyze the scalability of the M/S program performance.

To overcome inefficiencies on tree-based and mesh-based scheme, overlay multicast scheme for MANET has been recently proposed to provide higher packet delivery ratio than the former as well as more efficient resource usage than the latter. However, previous all overlay multicast schemes are not designed with any considerations for dense/sparse environments resulted from unlimited movement of mobile nodes. For this reason, all packets should be transmitted in the form of unicast packet so they cannot fully make use of node's broadcast capability even though some group members are densely distributed within single-hop on the same shared media. Due to above reason, this causes extra forwarding overhead, low resource utilization as well as high packet collision. In this paper, we propose a novel hybrid overlay multicast scheme, EAOM (Environment-Aware Overlay Multicast), which uses neighboring group members' information to deliver packet with low cost. In EAOM, a group member has two modes depending on the number of neighboring group members. Under dense environment, host group model in wired network is applied. While in sparse environment, packets are delivered to each receiver along overlay DDT (Data Delivery Tree) as same as previous overlay multicast schemes. Hence, EAOM can not only remove mentioned obstacles in dense environment, but also cope with network mobility very well in sparse environment. Using simulation results, we demonstrate that EAOM has good packet delivery ratio, low control overhead as well as short end-to-end delay.

Circuit partition, retiming and state reordering techniques are effective in reducing power consumption of circuits. In this paper, we propose a partition architecture and a methodology to reduce power consumption when designing low power IP, named PRC (Partition and Reordering Circuit). The circuit reordering synthesis flow consists of three phases: first, evenly partition the circuit based on the Shannon expansion; secondly encode the output vectors of each partition to build an equivalent functional logic. Finally, apply reordering algorithm to reorganize the logic function to reduce power consumption and decrease area cost. The validity of our architecture is proven by applying it to MCNC benchmark with simulation environment.

A new partitioning configuration that divides a given network into overlapped protection areas is investigated. If two working sub-paths are in the adjacent different working areas, their corresponding protection sub-paths can share a wavelength on the link that belongs to the overlap between two adjacent protection areas. The objective of overlapping is to increase sharing of the protection sub-paths that belong to the adjacent protection areas. The performances of resource utilization and recovery time are improved without any significant degradation of other performances.

We propose a new orthogonal frequency division multiplexing transmission scheme using orthogonal code multiplexing. This scheme makes all modulation symbols have the same reliability even in a frequency selective fading channel, through a distributed transmission of each symbol over the whole effective subcarriers using a distinct orthogonal code. As an appropriate set of orthogonal multiplexing codes, we use the set of discrete Fourier transform code sequences that hold the orthogonality irrespective of the length. Using this set, we also can greatly reduce the peak-to-average-power ratio (PAR) of the resulting signal. Simulation results show that the proposed scheme can significantly reduce the required signal-to-noise ratio at a given bit error rate over the existing schemes. The scheme can maintain the PAR within a reasonable range of about 6 dB even up to 512 subcarriers and works well even with PAR clipping of 1.5 dB.

In this paper we study a classical firing squad synchronization problem on a model of fault-tolerant cellular automata that have possibly some defective cells. Several fault-tolerant time-efficient synchronization algorithms are developed based on a simple freezing-thawing technique. It is shown that, under some constraints on the distribution of defective cells, any cellular array of length n with p defective cell segments can be synchronized in 2n - 2 + p steps.

In this paper a new adaptive multi-input multi-output (MIMO) channel estimation and multiuser detection algorithm based kernel space iterative inversion is proposed. The functions of output signals are mapped from a low dimensional space to a high dimensional reproducing kernel Hilbert space. The function of the output signals is represented as a linear combination of a set of basis functions, and a Mercer kernel function is constructed by the distribution function. In order to avoid finding the function f(.) and g(.), the correlation among the output signals is calculated in the low dimension space by the kernel. Moreover, considering the practical application, the algorithm is extended to online iteration of mixture system. The computer simulation results illustrated that the new algorithm increase the performance of channel estimation, the global convergence, and the system stability.

Coefficient-based test (CBT) is introduced for detecting parametric faults in analog circuits. The method uses pseudo Monte-Carlo simulation and system identification tools to determine whether a given circuit under test (CUT) is faulty.

The capabilities of reliable computations in one-dimensional cellular automata are investigated by means of the Early Bird Problem. The problem is typical for situations in massively parallel systems where a global behavior must be achieved by only local interactions between the single elements. The cells that cause the misoperations are assumed to behave as follows. They run a self-diagnosis before the actual computation once. The result is stored locally such that the working state of a cell becomes visible to its neighbors. A non-working (defective) cell cannot modify information but is able to transmit it unchanged with unit speed. We present an O(n log (n) log (n))-time fault-tolerant solution of the Early Bird Problem.

The partially rotational scan (PRS) technique greatly reduces the amount of data needed for n-detection testing. It also enables at-speed testing using low-speed testers. We designed tester intellectual properties (tester IP) with PRS for Viper and COMET II processors. When PRS was applied to a Viper processor, we obtained test data that provided the same fault coverage as with a set of automatic test pattern generation (ATPG) test vectors, although the amount of test data was 16% that of the ATPG. When the PRS technique was applied to a COMET II processor with full-scan design, we obtained test data that provided the same fault coverage as with a set of ATPG test vectors, although the amount of test data was 10% that of the ATPG. We also estimated hardware overhead and test time.