Recently, the number of users utilizing mobile communication services has increased greatly in many information and communication fields. In the future, the number of mobile communication system users will increase even faster, until the rate of diffusion ultimately reaches that of telephones. The day that each person has his own portable mobile terminal is not so far off. Moreover, the systems will not only be used as telephones but also as mobile computing for multimedia information. Digitalization technologies of mobile communication systems needed to realize such mobile computing will be introduced in this paper.

In this paper, a new trial for the signal processing is proposed along the same line as a previous study on the extended regression analysis based on the Bayes' theorem. This method enables us to estimate a response probability property of complicated systems in an actual case when observation values of the output response are roughly observed due to the quantization mechanism of measuring equipment. More concretely, the main purpose of this research is to find the statistics of the joint probability density function before a level quantization operation which reflects every proper correlation informations between the system input and the output fluctuations. Then, the output probability distribution for another kind of input is predicted by using the estimated regression relationship. Finally, the effectiveness of the proposed method is experimentally confirmed by applying it to the actually observed input-output data of the acoustic system.

This paper proposes a novel FEC (forward error correction) scheme for high-speed wireless systems aiming at mobile computing applications. The proposed scheme combines inner nonredundant error correction with outer parallel encoding random FEC for differentially detected QPSK (quadrature phase shift keying) signals. This paper, first, examines error patterns after the differential detection with nonredundant error correction and reveals that particular double symbol errors occur with relatively high probability. To improve the outer FEC performance degradation due to the double symbol errors, the proposed scheme uses I and Q channel serial to parallel conversion in the transmission side and parallel to serial conversion in the receiving side. As a result, it enables to use simple FEC for the outer parallel encoding random FEC without interleaving. Computer simulation results show the proposed scheme employing one bit correction BCH coding obtains a required Eb/No improvement of 1.2 dB at a Pe of 10-5 compared to that with the same memory size interleaving in an AWGN environment. Moreover, in a Rician fading environment where directional beam antennas are assumed to be used to improve the degradation due to severe multipath signals, an overall Eb/No improvement at Pe of 10-5 of 3.0 dB is achieved compared to simple differential detection when the condition of delay spread of 5 nsec, carrier to multipath signal power ratio of 20 dB and Doppler frequency at 20 GHz band of 150 Hz.

An extension is made for a set of systems that have a quadratic Lyapunov function in common for the purpose of analysis and design. The nominal set of system matrices comprises stable symmetric matricies, which admit a hyperspherical Lyapunov function. Based on stability robustness results, sets of matrices are constructed so that they share the same Lyapunov function with the nominal ones.

The computers are connected with each other by the network as a result of the progress of technology in the field of the computer and network, and then all of the data to be processed are transferred quickly and at the real-time through the computer network. However the user can use the computer system at any time, the user must go to the location of the computer system to use the computer resources. The necessities for using the computer system occur anywhere and anytime in spite of the location of the computer system. For this requirement the mobile computing environment (MCE) is expected strongly. In this paper we introduce the model of MCE and discuss the need of the user authentication at entering and logging-in the network in MCE only with a user ID. We propose the method of a user ID assignment from which a server ID can be decided by a simple logical operation. Also, we propose a protocol for a user authentication in MCE and discuss the robustness of security against the various attacking on the route.

This study was conducted to assess the relationship between fatigue and pupillary responses. Pupillary responses, ECG and blood pressure were measured for 24 hours every 30 min in 8 subjects. A questionnaire was used to rate subjective feeling of fatigue. Twenty-four hours were divided equally into four 6-hour blocks. Subjective feeling of fatigue increased markedly in the fourth block, and the difference in subjective fatigue between fourth and first blocks was significant. Of nine pupillary responses, the pupil diameter was found to decrease with time. With respect to the function of the autonomic nervous system such as heart rate, systolic blood pressure and diastolic blood pressure, only heart rate was found to be sensitive to the increased subjective feeling of fatigue. A significant difference was found in the mean pupil diameter and mean heart rate between the last and first blocks. This result indicates that pupil diameter is related to fatigue and can be used to assess fatigue. Possible implications for fatigue assessment are discussed.

Genetic algorithms were introduced by Holland in 1975 as a method of solving difficult optimization problems by means of simulated evolution. A major drawback of genetic algorithms is their slowness when emulated by software on conventional computers. Described is an adaptation of the original genetic algorithm that is advantageous to hardware implementation along with the architecture of a hardware framework that performs the functions of population storage, selection, crossover, mutation, fitness evaluation, and survival determination. Programming of the framework is illustrated with the set coverage problem that exhibits a 6,000 speed-up over software emulation on a 100 MHz workstation.

This paper describes the relation between the structure and the capability on mesh-connected computers with orthogonal broadcasting. It is shown that algorithms of maximum finding for the two-way communication model can be performed on the one-way communication model without increasing the time complexity.

This paper describes a neuro-based optimization algorithm for three dimensional (3-D) cylindric puzzles which are problems to arrange the irregular-shaped slices so that they perfectly fit into a fixed three dimensional cylindric shape. First, the idea to expand the 2-dimensional tiling technique to 3-dimensional puzzles is described. Next, to energy function with the fitting function of each polyomino is introduced, which is available for 3-D cylindric puzzles. Furthermore our algorithm is applied to several examples using the analog neural array. Finally, it is shown that our algorithm is useful for solving 3-D cylindric puzzles.

This paper describes a new Vector Sum Excited Linear Prediction (VSELP) coder with very low complexity. The method, called regular pulse VSELP (RP-VSELP), is based on regular pulse basis vectors with mutually orthonormal property. In this Approach, a very efficient vector-sum codebook is constructed from a set of mutually orthonormal regular pulse bassis vectors and enables us to simplify the codebook search without additional degradation of synthesized speech compared with that of the conventional VSELP. The regular pulse basis vectors are explicitly orthonormalized by means of the Gram-Schmidt procedure. To enhance the speech quality of the RP-VSELP speech coder, perceptually weighted distortion measure between the input and the synthesized speech is utilized in an iterative closedloop training process of the regular pulse basis vectors. It is shown that speech quality is improved by the training process. Experimental results demonstrate that the proposed method produces the synthesized speech quality comparable to that of the VSELP scheme at the bit-rate of 4.8 Kbps.

In contrast to previous algorithms for reconfiguring processor arrays under the assumption that spare rows and columns are placed on the perimeter of the array or on fixed positions, our new algorithm employs movable and partitionable spare rows and columns. The objective of moving and partitioning spare rows and/or columns is the elimination of faulty processors each of which is blocked in all directions to spare processors. The results of our computer simulation indicate that reconfigurability can significantly be improved.

The technique of common-multiplicand multiplication, CMM, is modified and the similar approach is utilized to enhance the performance of a recently proposed fast exponentiation algorithm by exponent decomposition. On average, the improved exponentiation, its original version, and the traditional right to left binary exponentiation algorithm take 1.292m+11,1.375m+3, and 1.5m multiplications, respectively where m is the bit length of the exponent. Finally, it is shown how to improve the overall performance of an exponentiation by employing the improved exponentiation algorithm, the improved CMM algorithm , and any general purpose fast multiplication algorithm.

As enterprises use ATM networks for their private networks and as these private networks use public ATM networks for wide area communication, the need for the customers to be able to manage both private and public networks is increasing. Currently, some standardization work is being done towards providing this capability to customers. In this paper, we propose a new customer network management (CNM) system architecture for the management of both private and public ATM networks in a uniform way. The particular features of the proposed architecture lies in the efficient support of the complex hierarchical TMN manager-agent relationships at M3 and M4 interfaces, and the support of SNMP and CMIP integration. The TMN hierarchical many-to-many manager-agent relationships are realized by the utilization of a CORBA-based Shared Management Knowledge (SMK) system. We have implemented a prototype of ATM CNM system, and measured the performance for the demonstration of the suitability of the proposed architecture.

In this paper, we propose an efficient task scheduling scheme, called CTS (Class-based Task Scheduling), to obtain high performance in terms of high system utilization and low waiting times for tasks. While a better submesh allocation scheme can improve system performance, an allocation policy alone cannot improve performance significantly. This is due to the fact that the FCFS task scheduling policy leads to large external fragmentation. The CTS strategy maintains four separate queues, one for each incoming task class. This avoids the blacking property incurred in the FCFS scheduling. To reduce the external fragmentation, a job tends to wait for an occupied submesh of the same size instead of using a new submesh in the CTS strategy. Simulation results indicate that the proposed scheduling strategy improves the performance compared to the FCFS scheduling policy by reducing the average waiting delay significantly.

This paper focuses on recovering from processor transient faults in pipelined multiprocessor systems. A pipelined machine may employ out of order execution and branch prediction techniques to increase performance, thus a precise computation state would not be available. We propose an efficient scheme to maintain the precise computation state in a pipelined machine. The goal of this paper is to implement checkpointing and rollback recovery utilizing the technique of precise interrupt in a pipelined system. Detailed analysis is included to demonstrate the effectiveness of this method.

The demand for data communication over Personal Handy-phone System (PHS) is expected to rapidly increase in the near future. Some applications based on the circuit-switched services have been recently developed. However, the packet-switched service is better than the circuit-switched service for personal data communications in terms of the flexible utilization of radio resources. In this paper, we propose PHS with packet data communications system (PHS-PD), which has four system concepts; (i) to supprot the Internet access, (ii) to realize compatibility with circuit-switching services, (iii) to share the common radio channels with circuit-switched calls, and (iv) to utilize idle time slots for packet data. Moreover, a novel packet channel structure for sharing radio resources with circuit-switched calls is introduced. Although packet data are transferred using common radio resources, the proposed channel structure prevents any degradation in call loss performance of the circuit-switching service. An evaluation of the maximum packet transmission rate shows that PHS-PD can offer a data communication rate of 20.1 kbps even if circuit-switched calls are in progress. Furthermore, up to 83.6 kbps is possible if circuit-switched calls are quiescent. It is also shown that enough capacity for a practical e-mail service can be ensured by PHS-PD even if the degradation of throughput performance due to packet collisions on random access channels is considered.

A new method is proposed for recovering an unknown source signal ,which is observed through two unknown channels characterized by non-minimum phase FIR filters. Conventional methods cannot estimate the non-minimum phase parts and recover the source signal. Our method is based on computing the eigenvector corresponding to the smallest eigenvalue of the input correlation matrix and using the criterion with the multi-channnel inverse filtering theory. The impulse responses are estimated by computing the eigenvector for all modeling orders. The optimum order is searched for using the criterion and the most appropriate impulse responses are estimated. Multi-channel inverse filtering with the estimated impulse responses is used to recover the unknown source signal. Computer simulation shows that our method can estimate nonminimum phase impulse responses from two reverberant signals and recover the source signal.

Microwave oven interference much degrades the performance of digital radio communication systems, and, in order to obtain a good error performance under microwave oven interference environment, the digital radio communication systems should be newly designed for microwave oven interference environment. In this paper, using the Middleton's canonical class-A impulsive noise model, we propose a statistical model of microwave oven interference and discuss the performance improvement achieved by an optimum reception based on this statistical model. As the results, although the first order statistic of microwave oven interference can be modeled by class-A impulsive noise, because of the burst high level interference, the performance of optimum receiver designed for class-A noise cannot achieve a good error performance under microwave oven interference environment. In order to eliminate the effect of burst high level interference, we introduce sample interleave scheme and show that the performance of optimum receiver can be much improved by using sample interleave scheme.

This paper describes cellular spaces (or cellular automata) with capabilities of parallel self-reproduction and of parallel universal simulation of other cellular spaces. It is shown that there is a 1-dimensional cellular space U, called a parallel universal simulator, that can simulate any given 1-dimensional cellular space S in the sense that if an initial configuration of U has a coded information of both the local function and an initial configuration of S, then U has the same computation result that S has and the computation time of U is proportional to that of S. Two models of nontrivial parallel self-reproduction are also shown. One model is based on "state-exchange" method, and the other is based on a fixed point program of the parallel universal simulator.

Some kind of practical problems such as security verification of cryptographic protocols can be described as a problem to accomplish a given purpose by using limited operations and limited materials only. To model such problems in a natural way, unification problems under constrained substitutions have been proposed. This paper is a collection of results on the decidability and the computational complexity of a syntactic unification problem under constrained substitutions. A number of decidable, undecidable, tractable and intractable results of the problem are presented. Since a unification problem under constrained substitutions can be regarded as an order-sorted unification problem with term declarations such that the number of sorts is only one, the results presented in this paper also indicate how the intractability of order-sorted unification problems is reduced by restecting the number of sorts to one.