This paper describes the results of a series of laboratory experiments for performance evaluations of our proposed Maximum Likelihood Sequence Estimation (MLSE) based interference canceller, the Interference Canceling Equalizer (ICE), which can cancel both co-channel interference (CCI) and inter-symbol interference (ISI). To verify the feasibility of ICE for the Japanese cellular communications system, a standard of which has been released under the name of Personal Digital Cellular (PDC) system, a prototype system was constructed using 27 TI TMS320C40 Digital Signal Processor (DSP) chips. The ICE prototype works in real-time on the PDC air interface, major specifications of which are π/4 QDPSK 21 k symbols/s 3-channel time-division multiple-access (TDMA). Two-branch diversity reception is used to enhance the signal detection performance of ICE. In the experiments, BER performances were evaluated using the prototype system. Under a single-path Rayleigh fading and a single CCI condition, the ICE receiver attains the BER of less than 310-2 with the negative values of the average CIR: for fD = 5 Hz and 40 Hz, the average CIR more than -20 dB and -10 dB, respectively. Under a double-path Rayleigh fading and a single CCI condition, the ICE receiver attains the BER of less than 1.510-2 with the negative values of the average CIR: for fD = 5 Hz and 40 Hz, the average CIR more than -20 dB and -10 dB, respectively. The laboratory test results suggest that the ICE receiver has potential for system capacity enhancement.

The reverse-link of the DS-CDMA cellular system requires transmit power control (TPC) and diversity reception. This paper develops the expression of the received signal-to-interference ratio (SIR), and evaluates the outage probability using the Monte Carlo simulation to obtain the link capacity. The link capacities with received signal strength (SS)-based TPC and SIR-based TPC are compared. This paper investigates the required maximum and minimum transmit powers and the capacity gain of the SIR-based TPC over SS-based TPC as well as the effect of the diversity reception on the link capacity and transmit power. The reverse-link capacity is compared with the forward-link capacity to check the balance of capacities between both links.

For evaluating the output response fluctuation of the actual environmental acoustic system excited by arbitrary random inputs, it is important to predict a whole probability distribution form closely connected with many noise evaluation indexes Lx, Leq and so on. In this paper, a new type evaluation method is proposed by introducing lower and higher order type functional models matched to the prediction of the response probability distribution form especially from a problem-oriented viewpoint. Because of the non-negative property of the sound intensity variable, the response probability density function can be reasonably expressed in advance theoretically by a statistical Laguerre expansion series form. The system characteristic between input and output can be described by the regression relationship between the distribution parameters (containing expansion coefficients of this expression) and the stochastic input. These regression functions can be expressed in terms of the orthogonal series expansion. Since, in the actual environment, the observed output is inevitably contaminated by the background noise, the above regression functions can not be directly employed as the models for the actual environment. Fortunately, the observed output can be given by the sum of the system output and the background noise on the basis of additivity of intensity quantity and the statistical moments of the background noise can be obtained in advance. So, the models relating the regression functions to the function of the observed output can be derived. Next, the parameters of the regression functions are determined based on the least-squares error criteria and the measure of statistical independency according to the level of non-Gaussian property of the function of the observed output. Thus, by using the regression functions obtained by the proposed identification method, the probability distribution of the output reducing the background noise can be predicted. Finally, the effectiveness of the proposed method is confirmed experimentally too by applying it to an actual indoor-outdoor acoustic system.

A merged analog-digital circuit architecture is proposed for implementing intelligence in SoC systems. Pulse modulation signals are introduced for time-domain massively parallel analog signal processing, and also for interfacing analog and digital worlds naturally within the SoC VLSI chip. Principles and applications of pulse-domain linear arithmetic processing are explored, and the results are expanded to the nonlinear signal processing, including an arbitrary chaos generation and continuous-time dynamical systems with nonlinear oscillation. Silicon implementations of the circuits employing the proposed architecture are fully described.

The variabilities of device characteristics are usually regarded as a normal distribution. If we consider the variabilities over the whole wafer, however, they cannot be expressed as a normal distribution due to the existence of global systematic component. We propose a statistical model, characterizing the global systematic component according to the distance from the center of the wafer, which can express the variabilities over the whole wafer statistically.

A novel Multi-Level Partitioning (MLP) technique taking into account real-world constraints for hardware-software partitioning in Distributed Embedded Multiprocessor Systems (DEMS) is proposed. This MLP algorithm uses a gradient metric based on hardware-software cost and performance as the core metric for selection of optimal partitions and consists of three nested levels. The innermost level is a simple binary search that allows quick evaluations of a large number of possible partitions. The middle level iterates over different possible allocations of processors (that execute software) to subsystems. The outermost level iterates over the number of processors and the hardware cost range. Heuristics are applied to each level to avoid the expensive exhaustive search. The application of MLP as a recently purposed Distributed Embedded System Codesign (DESC) methodology shows its feasibility. Comparisons between real-world examples partitioned using MLP and using other existing techniques demonstrate contrasting strengths of MLP. Sharing, clustering, and hierarchical system model are some important features of MLP, which contribute towards producing more optimal partition results.

The processes observed in a sound environment inevitably contain additional external noise of arbitrary distribution. Furthermore, the actual sound environment system exhibits various types of linear and non-linear characteristics, and it often contains an unknown structure. In this paper, a method for estimating the input signal for a sound environment system with unknown structure and additive noise of arbitrary probability distribution is proposed by introducing a system model of the conditional probability type. The effectiveness of the proposed theoretical method is confirmed experimentally by applying it to the actual problem of input estimation of the sound environment.

This paper presents a multi-thread evolutionary programming (MEP) technique that is composed of global, local, and minimal search units. An appropriate search routine is called depending on the current situation and the individuals are updated by using the selected routine. In each search routine, the individuals are updated with a normalized relative fitness function to improve the robustness of the algorithm. The proposed method is applied to the problem of backing up a truck-and-trailer system to a loading dock. A fuzzy logic controller is designed for a truck-and-trailer backer-upper system and the MEP algorithm is used to optimize the representative parameters of the fuzzy logic controller. The simulation results show that the proposed controller performs well even under a large variety of initial positions.

This paper proposes a new hybrid active noise control (ANC) system without the estimation of the secondary path filter in advance. The algorithm of the feedforward part of the proposed method is based on the simultaneous equations method and the feedback part employs the filtered-X LMS algorithm. The estimation of the secondary path filter is obtained in the operation of the feedforward part and it is used in the feedback part. When the secondary path changes in the operation of the system, the proposed system can follow to this change. In the simulation example which treats the colored measurement noise, the fine noise reduction performance is obtained.

This paper deals with the problem of autoregressive (AR) spectral estimation from a finite set of noisy observations without a priori knowledge of additive noise power. A joint technique is proposed based on the high-order and true-order AR model fitting to the observed noisy process. The first approach utilizes the uncompensated lattice filter algorithm to estimate the parameters of the over-fitted AR model and is one-pass. The latter uses the noise compensated low-order Yule-Walker (LOYW) equations to estimate the true-order AR model parameters and is iterative. The desired AR parameters, equivalently the roots, are extracted from the over-fitted model roots using a root matching technique that utilizes the results obtained from the second approach. This method is highly accurate and is particularly suitable for cases where the system of unknown equations are strongly nonlinear at low SNR and uniqueness of solution from the LOYW equations cannot be guaranteed. In addition, fuzzy logic is adopted for calculating the step size adaptively with the cost function to reduce the computational time of the iterative total search technique. Several numerical examples are presented to evaluate the performance of the proposed scheme in this paper.

A broadcast distribution system (BDS) is a system for the distribution of digital contents over broadcast channel where the data supplier broadcasts the contents in encrypted form and gives each subscriber a decoder containing a secret decryption key. A traitor is a subscriber who offers the information which allows to decrypt the broadcast. When a pirate decoder is captured, if at least one traitor can be identified from it, a BDS is said to be traitor-tracing. If the data supplier can prevent subscribers from obtaining the contents without recalling their decoders, a BDS is said to be subscriber-excluding. In this paper, we propose an efficient BDS which is both subscriber-excluding and traitor-tracing. We use similar mathematics to a threshold cryptosystem. In the proposed BDS, the maximum number of excluded subscribers reaches the maximum number of traitors in a coalition for which at least one traitor can be identified. We prove that the proposed BDS is secure against ciphertext-only attack if and only if ElGamal cryptosystem is secure against the attack and the discrete logarithm problem is hard. The proposed BDS is the first one which satisfies all the following features: Both subscriber-excluding and traitor-tracing, identifying all the traitors, black box tracing and public key system.

This paper surveys the research topics and results on nonlinear theory and its applications which have been achieved in Japan or by Japanese researchers during the last decade. The paticular emphasis is placed on chaos, neural networks, nonlinear circuit analysis, nonlinear system theory, and numerical methods for solving nonlinear systems.

ID-based key sharing scheme is one of the important topics in Key management, and the Key Predistiribution System (KPS) is one of the major divisions of such key sharing schemes. In KPS, in order to share a common key between the participants, one of the participants need to simply feed-in his partner's identifier value into their secret-algorithm. In contrast to its such remarkable property and its high contribution to the field of key management for digital signature, it has downsides as well. In this paper, we propose an efficient signature scheme on the KPS infrastructure that can overcome such difficulties that are faced. It is shown that if an ID-based key sharing system belonging to KPS is provided, the new digital signature scheme can be used straightforwardly. Moreover, this signature scheme is proven to be secure if the discrete logarithm is reasonably complex. There already exists other digital signature scheme which are also based on KPS, but they contain inevitable flaws: its verifier is restricted and a tamper resistant module(TRM) is required. Our method resolved these problems. In our signature scheme, it is an ensured fact that, all signatures are authenticated by any entity, which is based on the inherence behavior of key generator and not of some common key. Moreover, TRM is not required in our scheme. In order to describe our new scheme, a new concept of "one-way homomorphism" is introduced.

A passive branched optical network unified for broadcasting and communication utilizing a set of Fabry-Perot etalons with different cavity lengths is proposed and its basic operation including thermal stability of broadcasting channel is demonstrated. It is confirmed that a high transmission frequency in common for a pair of fiber Fabry-Perot etalons is always found however environmental temperature changes.

We present a distributed protocol for achieving totally unbiased global coin flipping in the presence of an adversary. We consider a synchronous system of n processors at most t of which may be corrupted and manipulated by a malicious adversary, and assume a complete network where every two processors are connected via a private channel. Our protocol is deterministic and assumes a very powerful adversary. Although the adversary cannot eavesdrop, it is computationally unbounded, capable of rushing and dynamic. This is the same model that is adopted in Yao's global coin flipping protocol, which we use as the base of our protocol. Our protocol tolerates almost n/3 processor failures and terminates in t+4 rounds. The resilience of our protocol is greatly improved from that of Yao's protocol at the slight expense of running time, which is only added just two rounds.

Efficient ID-based key sharing schemes are desired worldwide in order to obtain secure communications on the Internet and other related networks, and Key Pre-distribution System (KPS) is one of the majority of such key sharing schemes. The remarkable property of KPS, is that, user need only input the partner's identifier to the secret KPS-algorithm in order to share a key between them. Although this is just a small part of many advantages KPS has in terms of efficiency, an enormous amount of memory is always required to achieve perfect security. While the conventional KPS methods can establish communication links between any pair of entities in a communication system, in most of the practical communication environment, such as in a broadcast system, not all links will be required. In this article, we achieved a desirable method to remove the unnecessary communication links between any pair of entities in a communication system. In our scheme, required memory size per entity was just proportional to the number of entities of the partner's, while that in conventional KPS, it is proportional to the number of entities of the whole communication system. As an example, if an entity communicates with only 1/r others, the memory requirement is reduced to 1/r of the conventional KPS's. Furthermore, it was proven that the obtained memory size was optimum. Overall, our scheme confirmed greater efficiency to achieve secure communication particularly suited in large-scale networks.

A single-chip MPEG-2 video, audio, and system encoder LSI has been developed. It performs concurrent real-time processing of MPEG-2 422P@ML video encoding, 2-channel Dolby Digital or MPEG-1 audio encoding, and system encoding that generates a multiplexed transport stream (TS) or a program stream (PS). Advanced hybrid architecture, which combines a high performance VLIW media-processor D30V and hardwired video processing circuits, has been adopted to satisfy the demands of both high flexibility and enormous computational capability. A unified control scheme has been newly proposed that hierarchically manages adaptive task priority control over asynchronous video, audio, and system encoding processes in order to achieve real-time concurrent processing using a single D30V. Dual dedicated motion estimation cores consisting of a coarse ME core (CME) for wide range searches and a fine ME core (FME) for precise searches have been integrated to produce high picture quality while using a small amount of hardware. Adopting these features, a single-chip encoder has been fabricated using 0.25-micron 4-layer metal CMOS technology, and integrated into a 14.2 mm 14.2 mm die with 11 million transistors.

System LSI is a new principal product of semiconductor industry and also a key component of Information Technology (IT). Design of a system LSI contains two different characteristics, system design and LSI design. It is keen issue to establish a design methodology of system LSIs in which designers have much freedom on their design from system level to device level and also can control various design parameters to optimize their design. In this paper, considerations on markets of system LSIs and requirements from each application are summarized. Some proposals on new directions of design methodology are also surveyed.

Nowadays, when people colloquially use the word "wireless," they almost always mean a portable telephone. Over the last 10 years, there has been tremendous growth in the mobile communications markets not only in Japan but also worldwide. For these 10 years, the most popular service has been dominated by voice communication. However, modern mobile communications systems are shifting their focus from solely voice communication to electronic mailing and Internet access. From now, we will evolve into a wireless multimedia society, where a combination of mobile communications and the Internet will play an important role. Wireless technology is the core of mobile communications systems. This article, which focuses on wireless technology, looks at how mobile communications systems have evolved over the last 10 years and looks to the future of advanced wireless technologies that will be necessary to realize a true wireless multimedia society in the coming decade.

For distributed multimedia applications, the development of adaptive QoS (quality of service) management mechanisms is needed to guarantee various and changeable end-to-end QoS requirements. In this paper, we propose an adaptive QoS management framework based on multi-agent systems. In this framework, QoS management mechanisms are divided into two phases, the flow establishment and renegotiation phase and the media-transfer phase. An adaptation to system resource changes and various user requirements is accomplished by direct or indirect collaborations of the agents in each phase. In the flow establishment and renegotiation phase, application agents determine optimal resource allocation with QoS negotiations to maximize the total users' utility. In the media-transfer phase, stream agents collaborate to adjust each stream QoS reactively. In addition, personal agents help a novice user to specify stream QoS without any a priori knowledge of QoS. To make the interworking of agents tractable, a QoS mapping mechanism is needed to translate the QoS parameters from level to level, since the expression of QoS differs from level to level. As an example of multimedia application based on the proposed framework, a one-way video system is designed. The experimental results of computer simulation show the validity of the proposed framework.