This paper presents a non-scan design scheme to enhance delay fault testability of controllers. In this scheme, we utilize a given state transition graph (STG) to test delay faults in its synthesized controller. The original behavior of the STG is used during test application. For faults that cannot be detected by using the original behavior, we design an extra logic, called an invalid test state and transition generator, to make those faults detectable. Our scheme allows achieving short test application time and at-speed testing. We show the effectiveness of our method by experiments.

In this paper, the bit error rate (BER) and the outage probability are presented for a maximal ratio combining (MRC) two-dimensional (2D)-RAKE receiver operating in a correlated frequency-selective Nakagami-m fading environment with multiple access interference. A simple approximated probability distribution function of the signal-to-interference-plus-noise ratio (SINR) is derived for the receiver with multiple correlated antennas and RAKE branches in arbitrary fading environments. The combined effects of spatial and temporal diversity order, average received signal-to-noise ratio, the number of multiple access interference, angular spread, antennae spacing and multi-path Nakagami-m fading environment on the system performance are illustrated. Numerical results indicate that the performance of the 2D-RAKE receiver depends highly on the operating environment and antenna array configuration. The performance can be improved by increasing the spatio-temporal diversity gains and antenna spacing.

A new construction of sequences having both a low peak factor (crest factor) and flat power spectrum is proposed. The flat power spectrum provides zero auto-correlation except for the case of zero shift. The proposed construction is based on a systematic scheme that does not require a search, and affords sequences of length 4n(2n+1) for an arbitrary integer n.

A new analytical approach which reveals relationships between resonator parameters (unloaded Q-factor, coupling coefficient, and loaded Q-factor) and phase noise in microwave negative-resistance oscillators is presented. On the basis of Kurokawa's theory, this approach derives analytical expressions for the phase noise as a function of the resonator parameters (with particular emphasis on the coupling coefficient). Two types of negative-resistance oscillators--classified according to the manner in which the resonator is used in a circuit--are analyzed. These analyses use realistic circuit configurations and design procedures. The passive network connecting the active device and the resonator, which is shown to have important effects on the above-mentioned relationship, is taken into account. Validity of the new approach is verified through harmonic-balance simulations. The presented analytical approach can provide useful guidelines for choosing the resonator parameters, especially the value of the coupling coefficient, when designing microwave negative-resistance oscillators.

Signal integrity problem arises as one of the main issues in digital circuits manufactured by today's deep submicron technology. The coupling capacitance of neighboring lines may cause delays of circuit and it may affect the functionality of circuit. These effects are usually referred to as crosstalk. Since it requires additional design cost to fix crosstalk noise, the false aggressor nodes that cannot affect on victim node have to be eliminated. In this paper, we propose efficient heuristic algorithm that considers functional correlation for false aggressor pruning in crosstalk noise analysis. The false aggressors are detected by a path sensitization algorithm and logic implication. The efficiency of our algorithm has been verified on Benchmark circuits with a 0.18 µm standard cell library. Experimental results show an average of 5.4% false aggressor detection and an average improvement of 14.6% in the accuracy of timing analysis.

In wide-area wireless access systems such as satellite communications systems and stratospheric platform systems, electric power supplies for radio communications are realized using solar photovoltaic cells and/or fuel cells. However, the on-board weight limits restrict the number of cells that can be equipped. In addition, the transmission power of such systems is limited taking account of issues and regulations on sharing the same frequency band with other systems. Hence, both the frequency band and electric power is limited, which are crucial radio resources for those systems. Although radio channel allocation methods taking account of the frequency constraint only or the power constraint only have been proposed, radio channel allocation methods taking account of both constraints simultaneously have been insufficiently studied. This paper proposes a radio channel allocation method that provides global optimum allocation results by utilizing the linear programming method. The proposed method has features such that the method first allocates radio channels in proportion to the traffic demand distributed over the service coverage area and then maximizes the total radio channels allocated to systems. Numerical results are presented for a stratospheric platform system that covers an area of Japan, as an example, to demonstrate that the proposed method optimally allocates radio channels taking account of both constraints while efficiently allocating excess resources. In addition, whether a system reaches either the frequency or power limit can be estimated, by investigating the radio channel allocation results. Furthermore, enhanced linear programming models based on a method aiming at practical use of the radio channel allocation results in operation are also introduced. The enhanced model is demonstrated to work effectively to avoid unbalanced radio channel allocations over geographical areas. The proposed method and linear programming models are useful not only for making pre-plans but also for determining the amount of necessary frequency and power resources in designing systems.

This paper describes a new fast learning algorithm for Self-Organizing Map employing a "rough comparison winner-take-all" and its digital hardware architecture. In rough comparison winner-take-all algorithm, the winner unit is roughly and strictly assigned in early and later learning stage, respectively. It realizes both of high accuracy and fast learning. The digital hardware of the self-organizing map with proposed WTA algorithm is implemented using FPGA. Experimental results show that the designed hardware is superior to other hardware with respect to calculation speed.

In this paper, we consider the problem of multicast routing and wavelength assignment (MC-RWA) in multi-fiber all-optical WDM networks. Two main network design system comprehensively investigated here are mesh and multi-ring designs. Given the multicast traffic demands, we present new ILP formulations to solve the MC-RWA problem with an objective to determine the minimal number of fibers needed to support the multicast requests. Unlike previous studies, our ILP formulations are not only capable of finding the optimal multicast routing and wavelength assignment pattern to the light-trees, but also finding the optimal light-tree structures simultaneously. Since broadcast and unicast communications are special cases of multicast communications, our ILP models are actually the generalized RWA mathematical models of optical WDM networks. In addition to proposing the ILP models, this paper takes two main issues affecting the network capacity requirement into account, that is, the splitting degree level of optical splitters and techniques of wavelength assignment to the light-trees. Three multicast wavelength assignment techniques studied in this paper are Light-Tree (LT), Virtual Light-Tree (VLT) and Partial Virtual Light-Tree (PVLT) techniques. Due to the NP-completeness of the MC-RWA problem, the ILP formulations can reasonably cope with small and moderate networks. To work with large networks, this paper presents alternative MC-RWA ILP-based heuristic algorithms for the PVLT and LT networks and develops lower bound techniques to characterize the performance of our algorithms. Using existing large backbone networks, numerical results are reported to analyze such aspects as multiple fiber systems, the benefits of using optical splitters and wavelength converters, and the capacity difference between the mesh and multi-ring designs. Finally, this paper provides an analysis of the influence of network connectivity on the network implementation under the constraints of mesh and multi-ring design schemes.

A double surface light emission backlight that uses single light-guide plate, has been developed for illumination of two liquid-crystal displays (LCD) on its front and rear, to be used in a cellular phone. The light-guide plate has a trapezoid cross-section with arrays of optical micro deflector and micro prism on the front and the rear surfaces, respectively. Propagated light, forward and backward, inside the light-guide plate are controlled and directed toward LCDs using only two prism sheets with internal reflection characteristic, each for the front and the rear. Only three optical components and four light-emitting diodes (LEDs) are used in the new structure compared with ten components and six LEDs of the current type. Comparing with the current type, the thickness and power consumption of the new backlight are reduced by a factor of 0.59 and 0.67, respectively.

Reconfigurable logic circuitry has special importance because the popularity of Field Programmable Gate Arrays (FPGA) based applications. A reconfigurable logic based on FGMOS transistors, where a single stage can perform binary operations as well as state machines, is presented. The use of the proposed logic allows the integration of several stages into a single chip because their small area requirement, low voltage and low power characteristics.

Feedforward neural networks have been successfully developed and applied in many areas because of their universal approximation capability. However, there still remains the problem of determining a suitable network structure for the given task. In this paper, we propose a novel self-organizing neural network which automatically adjusts its structure according to the task. Utilizing both the constructive and the pruning procedures, the proposed algorithm finds a near-optimal network which is compact and shows good generalization performance. One of its important features is reliability, which means the randomness of neural networks is effectively reduced. The resultant networks can have suitable numbers of hidden neurons and hidden layers according to the complexity of the given task. The simulation results for the well-known function regression problems show that our method successfully organizes near-optimal networks.

This paper addresses the scheduling problem of a class of automated manufacturing systems with multiple resource requests. In the automated manufacturing system model, a set of jobs is to be processed and each job requires a sequence of operations. Each operation may need more than one resource type and multiple identical units with the same resource type. Upon the completion of an operation, resources needed in the next operation of the same job cannot be released and the remaining resources cannot be released until the start of the next operation. The scheduling problem is formulated by Timed Petri nets model under which the scheduling goal consists in sequencing the transition firing sequence in order to avoid the deadlock situation and to minimize the makespan. In the proposed genetic algorithm with deadlock-free constraint, Petri net transition sequence is coded and a deadlock detection method based on D-siphon technology is proposed to reschedule the sequence of transitions. The enabled transitions should be fired as early as possible and thus the quality of solutions can be improved. In the fitness computation procedure, a penalty item for the infeasible solution is involved to prevent the search process from converging to the infeasible solution. The method proposed in this paper can get a feasible scheduling strategy as well as enable the system to achieve good performance. Numerical results presented in the paper show the efficiency of the proposed algorithm.

Fairness is one of the most important features of a rate allocation strategy. Proportional fairness criterion has been recently proposed by F. P. Kelly and his colleagues. In this paper, we have proposed a two-level hierarchical technique which allocates proportionally-fair rates to the network elastic users. Part of the network links which are used commonly by the end-users and are congestion prone, constitute the higher (first) level of the hierarchy. In this level, the users with common path in the network are grouped as virtual users. End-users and remaining network links constitute the lower (second) level of hierarchy. To improve the convergence rate of the algorithm, a combination of Jacobi method and fuzzy techniques is deployed in the higher level of hierarchy. Implementing such fast algorithms in the higher level (which is topologically simpler than the whole network), reduces the computational complexity with respect to the use of such algorithms in the whole network. Additionally, the lower level penalty function computation is done once in each N iterations, which reduces the computational complexity furthermore. The simulation results show that the proposed algorithm outperforms that of Kelly in the convergence speed.

The effect of feedback delay and channel estimation error on closed-loop transmit diversity (CTD) systems is investigated in time-selective Rayleigh fading channels. Based on a minimum mean square error (MMSE) channel estimator, the variance of the estimation error is formulated in terms of fading index and the number of transmit antennas. A bit error rate (BER) expression for the CTD system is analytically derived as a function of channel estimation error, feedback delay, and fading index. It is shown that the BER performance of the CTD system improves as the length of training symbols increases and/or the frame length decreases. In the CTD system, more accurate channel estimation scheme is required to achieve its full gain as the number of employed transmit antennas increases. It is also found that the CTD system is applicable to the slowly moving channel environments, such as pedestrians, but not for fast moving vehicles.

An efficient data transmission interface for VLSI systems, Multi-Bit Parallel Code Division Multiple Access (MB/P-CDMA) interface, has been designed with 0.35 µm CMOS technology. The proposed interface achieves 1.12 Gb/s data rate (80 MHz, 8 bit bus) using multi-bit transmission at each clock per transmitter. The proposed CDMA interface ensures higher speed operation than conventional interface even in noisy environments. Each of the transmitters and receivers occupies the die area of 290 360 µm2 and 240 280 µm2, respectively.

Many simulated annealing algorithms use the Cauchy neighbors for fast convergence, and the conventional method uses the product of n one-dimensional Cauchy distributions as an approximation. However, this method slows down the search severely as the dimension gets high because of the dimension-wise neighbor generation. In this paper, we analyze the orthogonal neighbor characteristics of the conventional method and propose a method of generating symmetric neighbors from the n-dimensional Cauchy distribution. The simulation results show that the proposed method is very effective for the search in the simulated annealing and can be applied to many other stochastic optimization algorithms.

This paper investigates a random-interleaver-based approach to space-time coding. The basic principle is to employ a good forward error correction (FEC) code and transmit randomly interleaved codewords over an antenna array. A low-cost estimation technique is considered. The complexity involved grows only linearly with the number of transmit antennas. Near-capacity performance can be achieved with moderate complexity.

Direct manipulation by hand is an intuitive and simple way of positioning objects in an immersive virtual environment. However, this technique is not suitable for making precise adjustments to virtual objects in an immersive environment because it is difficult to hold a hand unsupported in midair and to then release an object at a fixed point. We therefore propose an alternative technique using a virtual 3D gearbox widget that we have designed, which enables users to adjust values precisely. We tested the technique in a usability study along with the use of hand manipulation and a slider. The results showed that the gearbox was the best of the three techniques for precise adjustment of small targets, in terms of both performance data and subject preference.

In this paper, a novel carrier-sense multiple-access (CSMA) scheme for UWB ad-hoc network is proposed and evaluated. UWB is a kind of spread spectrum communication and it is possible to detect the distance between the nodes. With this positioning capability of the UWB systems, DS-CDMA (DS-UWB) scheme with variable spreading factor is used. In this paper, a novel CSMA scheme that employs the correlation of the spreading code is proposed.

We propose use of QR factorization with sort and Dijkstra's algorithm for decreasing the computational complexity of the sphere decoder that is used for ML detection of signals on the multi-antenna fading channel. QR factorization with sort decreases the complexity of searching part of the decoder with small increase in the complexity required for preprocessing part of the decoder. Dijkstra's algorithm decreases the complexity of searching part of the decoder with increase in the storage complexity. The computer simulation demonstrates that the complexity of the decoder is reduced by the proposed methods significantly.