This paper describes a new architecture-based microprocessor, a dynamically programmable parallel processor (DPPP), that consists of large numbers of simplified ALUs (sALU) as processing blocks. All sALUs are interconnected via a code division multiple-access bus interface that provides complete routing flexibility by establishing connections virtually through code-matching instead of physical wires. This feature is utilized further to achieve high parallelism and fault tolerance. High fault tolerance is realized without the limitations of conventional fabrication-based techniques nor providing spare elements. Another feature of the DPPP is its simple programmability, as it can be configured by compiling numerical formula input using the provided user auto-program interface. A prototype chip based on the proposed architecture has been implemented on a 4.5 mm 4.5 mm chip using 0.6 µm CMOS process.

This letter presents an efficient graph-based evolutionary optimization technique, and its application to the transistor-level design of multiple-valued arithmetic circuits. The key idea is to introduce "circuit graphs with colored terminals" for modeling heterogeneous networks of various components. The potential of the proposed approach is demonstrated through experimental synthesis of a radix-4 signed-digit (SD) full adder circuit.

This paper presents the performance of the Directionally Constrained Minimization of Power (DCMP) and the Zero-Forcing (ZF) in the Angular Spread (AS) environment. To obtain the optimal weights for both methods, the Extended Array Mode Vector (EAMV) is employed. It is known that the EAMV represents the instantaneous AS as well as the instantaneous DOA in the slow fading channel. As a result, it is shown that the DCMP and the ZF using the EAMV estimates can improve the Signal-to-Interference-plus-Noise Ratio (SINR) considerably, as compared with those using the Direction of Arrival (DOA) information only. At the same time, the intrinsic problems causing the performance loss in the DCMP and the ZF are revisited. From this, the reasons for the performance deterioration are analyzed, in relation with the AS, the number of samples, the number of antenna elements, and the spatial correlation coefficient of the signals. It follows that the optimal signal combining techniques using the EAMV estimates can diminish such effects.

In this paper, we propose the evolutionary algorithm-based reasoning system and its design methodology. In the proposed design methodology, reasoning rules behind the past cases in each task (in each case database) are extracted through genetic algorithms and are expressed as truth tables (we call them 'evolved truth tables'). Circuits for the reasoning systems are synthesized from the evolved truth tables. Parallelism in each task can be embedded directly in the circuits by the hardware implementation of the evolved truth tables, so that the high speed reasoning system with small or acceptable hardware size is achieved. We developed a prototype system using Xilinx Virtex FPGA chips and applied it to the gene boundary reasoning (GBR) and English pronunciation reasoning (EPR), which are very important practical tasks in the genome science and language processing field, respectively. The GBR and the EPR prototype systems are evaluated in terms of the reasoning accuracy, circuit size, and processing speed, and compared with the conventional approaches in the parallel AI and the artificial neural networks. Fault injection experiments are also carried out using the prototype system, and its high fault-tolerance, or graceful degradation against defective circuits that suits to the hardware implementation using wafer scale LSIs is demonstrated.

The optical structure of a conventional backlight illumination system used for transmissive LCD of a mobile terminal is investigated. A structured LGP based on the total internal reflection is designed and fabricated. The LGP is characterized by optical micro-deflectors (MD) and micro-reflectors (MR). The guided light inside the LGP is reflected on the MR elements and directed toward the MD elements. The coming light ray is refracted on the MD element and as a result the ray is deflected on the LGP. The emergent light on the LGP has a wide zenith angle due to the LGP surface normal. A prism sheet whose function is based on the total internal reflection is set on the LGP. The emanated light from the LGP is reflected on the surface of the prism structure and redirected toward the surface normal. The illumination cone of the novel backlight is limited to horizontal range of 17 degrees and vertical range of 11 degrees. The illumination cone on the novel structure can be shaped by optical designs of the MD and MR elements. The peak brightness on the novel backlight structure is 1.44 times that of the conventional one. In this backlight structure, only one TIR prism sheet is used and a thickness reduction of about 250 µm is achieved.

This paper presents a variable rate transmission scheme suitable for bandlimited meteor burst channel. Meteor Burst Communication (MBC) is a unique type of radio communication, which is primarily used for non-realtime remote data collection. In the paper, along with conventional BPSK and QPSK modulations, QAM and M-ary Bi-orthogonal modulations are analyzed for software modem implementation in an MBC system. Performance of the modulation methods is presented for both static AWGN channel and meteor burst channel. The proposed scheme for variable rate transmission dynamically estimates the MBC channel and varies the modulation type of a software modem, to control the transmission rate between bursts. The scheme dynamically selects a modulation type and packet length that will maximize the average throughput of the system. Performance of the scheme is analyzed and compared with conventional fixed rate modems. A practical implementation for software modem is suggested that uses a common core modulator/demodulator structure.

A new architecture and methods for an enhanced autonomous decentralized production system (EADPS) are described. This EADPS was developed to ensure high flexibility of production systems consisting of intelligent devices based on the autonomous decentralized system model and to guarantee the time used for communication to simultaneously maintain high productivity. The system architecture of the EADPS guarantees the time by managing groups of nodes and the priorities in these groups. A bit-arbitration method is used to prevent collision of messages. The nodes autonomously check the waveforms in the network and terminate transmission when the nodes with a higher priority are transmitting. A parallel-filtering method is used to speed up message acceptance. The nodes check the identifiers of the messages using parallel-filtering circuits and each node determines autonomously where a message should be accepted or not. Implementing the system architecture and these methods as circuits and integrating the circuits into a chip using system LSI technologies resulted in low-cost implementation of the system. Experimental evaluation demonstrated the effectiveness of this system.

RC6 is a common-key block cipher that was proposed as one of the AES candidates. Although any weakness of RC6 in the use of the confidentiality is not known, Saarinen pointed out the existence of almost equivalent keys in RC6 with 176-byte keys. This means that the Davies-Meyer hash function based on RC6 with 176-byte keys is not a good collision-resistance function. However, Saarinen could not find a precise collision of it. In this paper, we propose a practical method for obtaining a collision of the Davies-Meyer hash function based on RC6-32/20/176. In other words, there exist equivalent user supplied keys in RC6-32/20/176, and it is possible to obtain them practically. This means that the essential key space of RC6-32/20/176 is smaller than the space provided by 176-byte keys. Our computer simulation shows that a collision can be found in about 100 minutes. We should notice that the result of this paper does not affect the security of the AES version of RC6 because RC6-32/20/176 discussed in this paper is different from the parameter of the AES version.

An improved arithmetic coding which provides an encoder with finite calculation precision for source sequences over a countable alphabet is presented. Conventional arithmetic coding theoretically has infinite precision for real variables. However any algorithm implemented on a computer has finite precision. This implies that conventional arithmetic codes can only encode sequences over a finite alphabet. The improved arithmetic coding presented here has a computational complexity which is roughly proportional to the length of the source sequence for a given source.

The even-odd transform (EOT) converts a complex sequence set into another one with even and odd correlation distributions exchanged. The Fukumasa-Kohno-Imai transform (FKIT) converts a real-valued sequence set into a complex one with improved generalized even-odd-equivalent (EOE) correlation distributions. In this work, the EOT is generalized for asynchronous M-PSK/CDMA. A subclass of the generalized EOTs coincides with the FKITs. New bounds on the correlation gains achievable by the FKITs are then derived.

In this paper, we propose an approach to solve the power control issue in a DS-CDMA cellular system using genetic algorithms (GAs). The transmitter power control developed in this paper has been proven to be efficient to control co-channel interference, to increase bandwidth utilization and to balance the comprehensive services that are sharing among all the mobiles with attaining a common signal-to-interference ratio(SIR). Most of the previous studies have assumed that the transmitter power level is controlled in a constant domain under the assumption of uniform distribution of users in the coverage area or in a continuous domain. In this paper, the optimal centralized power control (CPC) vector is characterized and its optimal solution for CPC is presented using GAs in a large-scale DS-CDMA cellular system under the realistic context that means random allocation of active users in the entire coverage area. Emphasis is put on the balance of services and convergence rate by using GAs.

We study the reliability functions or the minimum r-achievable rates of the lossless coding for the general sources in the sense of Han-Verdu, where r means the exponent of the error probability. Han has obtained formulas for the minimum r-achievable rates of the general sources. Our aim is to give alternative expressions for the minimum r-achievable rates. Our result seems to be a natural extension of the known results for the stationary memoryless sources and Markov sources.

In variable-length coding, the probability of codeword length per source letter being above (resp. below) a prescribed threshold is called the overflow (resp. the underflow) probability. In this paper, we show that the infimum achievable threshold given the overflow probability exponent r always coincides with the infimum achievable fixed-length coding rate given the error exponent r, without any assumptions on the source. In the case of underflow probability, we also show the similar results. From these results, we can utilize various theorems and results on the fixed-length coding established by Han for the analysis of overflow and underflow probabilities. Moreover, we generalize the above results to the case with overflow and underflow probabilities of codeword cost.

A universal channel decoder for a given family of channels is a decoder that can be designed without prior knowledge of the characteristics of the channel. Nevertheless, it still attains the same random coding error exponent as the optimal decoder tuned to the channel. This paper investigates the duality between universal channel decoders and universal source encoders. First, for the family of finite-state channels, we consider a sufficient condition for constructing universal channel decoders from universal source encoders. Next, we show the existence of a universal channel code that does not depend on the choice of the universal decoder.

Performance of parallel concatenated trellis-coded modulation (turbo TCM) with Ungerboeck type constituent codes with maximum likelihood decoding over the AWGN channel is analyzed by extending the method of performance evaluation proposed by Benedetto et al. for binary turbo codes with uniform interleaving. Although a performance evaluation of turbo TCM has been proposed, the system model discussed in the proposal has some auxiliary interleavers only necessary for the evaluation. This paper removes such auxiliaries. Since the direct extension of Benedetto's method for turbo TCM needs huge memories for computation, an efficient numerical evaluation method is proposed in order to reduce the memory requirement. Based on the analysis, the relation between bit error rate and interleaver size is discussed. The analyzed performance is compared with simulation results of iterative decoding of turbo TCM.

The sub-recursive least squares (sub-RLS) algorithm estimates the coefficients of adaptive filter under the least squares (LS) criterion, however, does not require the calculation of inverse matrix. The sub-RLS algorithm, based on the different principle from the RLS algorithm, still provides a convergence property similar to that of the RLS algorithm. This paper first rewrites the convergence condition of the sub-RLS algorithm, and then proves that the convergence property of the sub-RLS algorithm successively approximates that of the RLS algorithm on the convergence condition.

Single-hop communication methods of the current wireless network cannot meet new demands in new domains, especially ITS (Intelligent Transport Systems). Even though the ad-hoc network architecture is expected to solve this problem, but the nature of a dynamic topology makes this routing hard to be realized. This paper introduces a new ad-hoc routing algorithm, which is inspired by [1]. In their system, some control agents explore the network and update routing tables on their own knowledge. Using these routing tables, other agents deliver messages. They considered the feasibility of the agent-based routing system, but did not refer to an efficient algorithm. In this paper, we consider that algorithm without increasing network load. We propose multiple entries for each destination in the routing table to store much more information from agents and evaluating them to make better use of information, which succeeded in raising the network connectivity by about 40% by simulation.

In 2000, Wang et al. proposed a new (t,n) threshold signature scheme with (k,l) threshold shared verification. Meanwhile, integrating the idea of message recovery, they also proposed a (t,n) threshold authenticated encryption scheme with (k,l) threshold shared verification. However, this article will show that both proposed schemes are insecure, because any malicious attacker can obtain the group secret keys from two valid threshold signatures. Thus, the attacker may solely forge or verify a threshold signature. An improvement to overcome the attacks is proposed.

This paper proposes a bandwidth division type parallel combinatory (PC) spread spectrum (SS) modulation scheme. In the proposed system, a given system bandwidth for the conventional single-carrier PC-SS system is divided into H subbands, and H PC-SS signals are transmitted in parallel. We evaluate the frame error rate (FER) of the proposed system under the asynchronous CDMA environment. We show that the proposed scheme provides a smaller FER than the single-carrier PC-SS system for a given information bit rate. We also show that the proposed scheme attains a higher information bit rate than the single-carrier PC-SS system for a given FER.

The reduction of the drain current for InGaAs/AlGaAs pseudomorphic high electron mobility transistors (PHEMTs) has been observed due to the RIE-damage induced under the gate region. However, it has been found that the drain current can be recovered after the gate-drain reverse current stress even at room temperature. The recovery rate of the drain current strongly depends on the gate-drain reverse current density. The activation energy of the recovery rate has been confirmed to decrease from 0.531 eV to 0.119 eV under the gate-drain reverse current stress. This phenomenon can be understood as a recombination enhanced defect reaction of holes generated by the avalanche breakdown. The non-radiative recombination of holes at the defect level is believed to enhance the recovery of the RIE-damage.