This paper describes the multiple access performance of parallel combinatory spread spectrum (PC/SS) communication systems in nonfading and Rayleigh fading multipath channels. The PC/SS systems can provide the high-speed data transmission capability by transmitting multiple pseudo-noise sequences out of a pre-assigned sequence set. The performance is evaluated in terms of average bit error rate (BER) by numerical computation. In nonfading white gaussian channel, the PC/SS systems are superior to conventional direct sequence spread spectrum (DS/SS) systems under the identical spreading factor condition. In Rayleigh fading channel, the performance of the PC/SS system without diversity is poorer than that of the DS/SS system. By including the explicit and implicit diversity, the performance of the PC/SS system becomes better than that of conventional DS/SS systems. A longer spreading sequence is assignable to a PC/SS system having the spreading factor equal to that in the conventional DS/SS system. Hence, the error control coding is easily. It is found that the PC/SS systems including diversity and Reed-Solomon coding improves the multiple access performance.

In case of object recognition using 3-D configuration data, the scale and poses of the object are important factors. If they are not known, we can not compare the object with the models in the database. Hence we propose a strategy for object recognition independently of its scale and poses, which is based on Hopfield neural network. And we also propose a strategy for estimation of the camera motion to reconstruct 3-D configuration of the object. In this strategy, the camera motion is estimated only with the sequential images taken by a moving camera. Consequently, the 3-D configuration of the object is reconstructed only with the sequential images. And we adopt the multiple regression analysis for estimation of the camera motion parameters so as to reduce the errors of them.

This paper presents a theoretically best algorithm within the framework of our image noise model for reconstructing 3-D from two views when all the feature points are on a planar surface. Pointing out that statistical bias is introduced if the least-squares scheme is used in the presence of image noise, we propose a scheme called renormalization, which automatically removes statistical bias. We also present an optimal correction scheme for canceling the effect of image noise in individual feature points. Finally, we show numerical simulation and confirm the effectiveness of our method.

This paper describes a flexible point-to-multipoint access protocol for the fiber-optic passive double star (PDS) system. To provide various types of services, and permit flexibility in changing transport capacity, a time division multiple access (TDMA) scheme for the PDS system is considered. Dynamic time slot multiplexing based on TDMA is proposed to provide required time slots efficiently according to service changes. The effectiveness of dynamic time slot multiplexing is calculated and compared to fixed time slot multiplexing for telephony services. A TCM/TDMA frame structure and an access protocol enabling dynamic time slot multiplexing are proposed. ONU bandwidth is dynamically assigned by using a set of pointers. The ONU access protocol causes no interruption to operating ONUs on the same PDS system during the configuration or reconfiguration of an ONU. The access time is analyzed to estimate the performance of the access protocol. The probability density of access time is calculated for the number of ONUs connected. The calculation results indicate that a PDS system can accommodate up to around 60 ONUs within the maximum access time specified by ITU-T. The experimental results also agree fairly well with the theoretical values.

A novel wireless multimedia network employing a time division duplex CDMA/TDMA scheme is proposed. The network connects mobile multimedia terminals to an ATM based LAN through a radio central unit, and provides both uplink and downlink with unbalanced data rates in the same frequency band. The uplink (from a mobile terminal to a radio central unit) employs a CDMA scheme to transmit low speed human interface signals (-2.4kbit/s), and the downlink employs a TDMA scheme to transmit high speed video signals (-24Mbit/s). The data rates of both links are independent from that of the LAN. The uplink also employs a RAKE receiver and a forward error correction (FEC) scheme using a BCH code in order to reduce bit errors caused by multipath fading. To mitigate channel degradation caused by the near-far problem and multipath fading, a transmission power control (TPC) method for both links and a channel equalizer (CEQ) for the downlink are proposed. The control signals for the TPC and the CEQ are estimated from the impulse response of the channel which is extracted as the output of the matched filters in the CDMA receiver. Theoretical analyses are performed to evaluate the bit error rate (BER) characteristics of the proposed network. The BER performance is derived for a general multipath fading condition modeled by the Nakagami-m distribution and a typical delay profile. Numerical calculation using recent propagation measurements shows the bit error rates of both uplink and downlink to be less than 10-6 when both of the TPC and the CEQ are employed if there are some specular components in the received signals. This excellent performance can cut a way to realize a mobile multimedia terminal for customer premises. Furthermore, the configuration of the mobile terminal is quite simple even if the high speed TDMA signals are received over a multipath fading channel.

This paper presents the concept of k-FR circuits. The controllability of such a circuit is high due to its special structure. It is shown that all stuck-at faults and stuck-open faults in a k-FR circuit can be detected and located by k(k1)1 test vectors under the highly observable condition which assumes the output of every gate to be observable. k is usually two or three. This paper also presents an algorithm for converting an arbitrary combinational circuit into a k-FR circuit. A k-FR circuit is easy to test when using technologies such as the electron-beam probing, the current measurement, or the CrossCheck testability solution.

This paper studies the problem of reconstructing a planar surface from stereo images of multiple feature points that are known to be coplanar in the scene. We present a direct method by applying maximum likelihood estimation based on a statistical model of image noise. The significant fact about our method is that not only the 3-D position of the surface is reconstructed accurately but its reliability is also computed quantitatively. The effectiveness of our method is demonstrated by doing numerical simulation.

This paper describes the imaging method for a human forearm in the microwave transmission CT at 3GHz. To improve the spatial resolution, the correction method of the diffraction effects is adopted and the high directivity antennas are used. A cross-sectional image of the human forearm is obtained in vivo.

With a view toward the improvement of life-saving rate, the advancement of emergency radio system was attempted. The telemetry technique was introduced to the mobile communication from a running ambulance. A system was newly developed which enables us to transmit the information of an emergency patient from an ambulance to an emergency room of a hospital. This system can transmit an audio signal, physiological signals such as an ECG and a blood oxygen level, as well as a color image. In the experiment, the feasibility of this technique was verified. In the test of its practical usefulness, the following points were evaluated using a mobile telephone line and an emergency radio link. With the regular condition of the communication link, the stability of signal transmission was reasonably well. The fidelity of the transmitted signal was satisfactory for the use of an emergency medicine.

This paper presents a newly developed analytical method which evaluates the virtual path bandwidth control effects for a general topology ATM (Asynchronous Transfer Mode) transport network. The virtual path concept can enhance the controllability of path bandwidth. Required link capacity to attain a specified call blocking probability can be reduced by applying virtual path bandwidth control. This paper proposes an analytical method to evaluate the call blocking probability of a general topology ATM network, which includes many virtual paths, that is using virtual path bandwidth control. A method for the designing link capacities of the network is also proposed. These methods make it possible to design an optimum transport network with path bandwidth control. Finally, a newly developed approximation technique is used to develop some analytical results on the effects of dynamic path bandwidth control are provided to demonstrate its effectiveness.

This paper investigates a different method of speaker adaptation for Mandarin syllable recognition. Based on the minimum classification error (MCE) criterion, we use the generalized probabilistic decent (GPD) algorithm to adjust interatively the parameters of the hidden Markov models (HMM). The experiments on the multi-speaker Mandarin syllable database of Telecommunication Laboratories (T.L.) yield the following results: 1) Efficient speaker adaptation can be achieved through discriminative training using the MCE criterion and the GPD algorithm. 2) The computations required can be reduced through the use of the confusion sets in Mandarin base syllables. 3) For the discriminative training, the adjustment on the mean values of the Gaussian mixtures has the most prominent effect on speaker adaptation. 4) The discriminative training approach can be used to enhance the speaker adaptation capability of the maximum a posteriori (MAP) approach.

A parallel blower system is quite familiar in hydraulic machine systems and quite often employed in many process industries. It is dynamically dual to the fundamental functional element of digital computer, that is, the flip-flop circuit, which was extensively studied by Moser. Although the global dynamic behaviour of such systems has significant bearing upon system operation, no substantial study reports have hitherto been presented. Extensive research concern has primarily been concentrated upon the local stability of the equilibrium point. In the paper, a piecewise linear model is used to analytically and numerically investigate its manifold global dynamic behaviour. To do this, first the Poincar map is defined as a composition boundary map, each of which is defined as the point transformation from the entry point to the end point of any trajectory on some boundary planes. It was already shown that, in some parameter region, the system exhibits the so-called chaotic states. The chaos generating process is investigated using the above Poincar map and it is shown that the map contains the contracting, stretching and folding operations which, as we often see in many cases particularly in horse shoe map, produce the chaotic states. Considering the one dimensional motions of the orbits by such Poincar map, that is, the stretching and folding operations, a one dimensional approximation of the Poincar map is introduced to more closely and exactly study manifold bifurcation processes and some illustrative bifurcation diagrams in relation to system parameters are presented. Thus it is shown how many types of bifurcations like the Hopf, period doubling, saddle node, and homoclinic bifurcations come to exist in the system.

Three-dimensional vocal tract shapes of a male, a female and a child subjects are measured from magnetic resonance (MR) images during sustained phonation of Japanese vowels /a, i, u, e, o/. Non-uniform dimensional differences in the vocal tract shapes of the subjects are quantitatively measured. Vocal tract area functions of the female and child subjects are normalized to those of the male on the basis of non-uniform and uniform scalings of the vocal tract length and compared with each other. A comparison is also made between the formant frequencies computed from the area functions normalized by the two different scalings. It is suggested by the comparisons that non-uniformity in the vocal tract dimensions is not essential in the normalization of the five Japanese vowels.

This paper reviews very high-speed optical signal processing technology based on the instantaneous characteristic of optical nonlinearities. Focus is placed on 100-Gbit/s optical time-division multiplexing (TDM) transmission systems. The key technologies including ultrashort optical pulse generation, all-optical multiplexing/demultiplexing and optical timing extraction techniques are alse described together with their major issues and future prospects.

Recent technical advances in WDM (Wavelength Division Multiplexing) technologies suggest that their practical application is imminent. By adopting WDM technologies in the transport network, a bandwidth abundant B-ISDN could be realized cost-effectively. This requires the introduction of WDM technologies, especially into the path layer. This paper explores optical path cross-connect (OPXC) nodes that offer very high levels of expandability because existing traffic demands, which are rather limited, must be efficiently supported while permitting easy step-wise expansion in capacity. This paper highlights modularity with regard to incoming/outgoing links. The OPXC architecture that offers the highest modularity is elaborated, and its transmission characteristics, optical loss and switching power consumption are evaluated. This paper also examines OPXC architecture considering the interface needed to connect electrical path cross-connects. The proposed OPXC architectures provide flexibility and minimum investment to encourage the early introduction of B-ISDN and also supports incremental network growth to match traffic demand. The design of OPXC parameters in terms of transmission performance is shown to ensure the applicability of the proposed OPXC architecture to long-haul optical fiber transmission networks. This is made possible with the low optical component losses offered by the OPXC. The proposed OPXC architectures will, therefore, be applied not only to regional networks, but also to global area networks. Thus they will play a key role in realizing the optical path infrastructure for the future bandwidth abundant B-ISDN.

With the foreseen growth of communication capacity, further capacity and flexibility enhancements are required for future transport networks. Photonic switching is expected to be a key technology to solve the potential bottleneck, which could be found in transport network nodes. This paper first explains the "Optical Fiber Freeway" concept, as an example of future transport networks. Following this, the possible optical transport network structure using photonic switching technologies, for realizing the Optical Fiber Freeway concept, is explained. An Optical CrossConnect (OXC) and optical Add/Drop Multiplexer (ADM) are key components. Examples of recent development of photonic switching systems toward these targets are also reviewed. An OXC using photonic Space-Division (SD) switching technology has been proposed and demonstrated. This type of OXC will realize flexible reconfiguration and optical hitless switching, and it can meet the introduction of Wavelength Division Multiplexing (WDM) technique. Line failure restoration operation at 2.4Gb/s has been successfully demonstrated. An optical packet network with a slotted ring/bus structure using a wavelength address technique has been proposed as a packet/cell based optical ADM. The experimental system employs a practical media access control system as well as a fast-wavelength switched transmitter suppressing thermally induced wavelength drift. Cell communication at 622Mb/s has been demonstrated with the experimental system. These results show that hardware technologies have been developed steadily. With a future study on an all optical network management scheme, a high capacity and flexible optical network would be realized.

The intermodulation distortion (IMD) due to laser diode (LD) nonlinearity of an asynchronous direct-sequence code division multiple access (DS/CDMA) system in optical transmission is analyzed. A third-order polynomial without memory is used to present LD nonlinearity. In DS/CDMA systems, only one harmonic of the third-order inter-modulation term falls on the signal frequency band and influences the system performance. The average distortion is derived with only the information of autocorrelation functions. The results are useful for CDMA system design and performance analysis. With LD nonlinearity it is necessary to select an optimal modulation index that provides a maximum signal-to-noise ratio (SNR). The analytical method is applicable to other general nonlinearities in CDMA systems.

This paper concerns the issue of learning strategies for problem solvers from trace data. Many works on Explanation Based Learning have proposed methods for speeding up a given problem solver (or a Prolog program) by optimizing it on some subspace of problem instances with high probability of occurrences. However, in the current paper, we discuss the issue of identifying a target strategy exactly from trace data. Learning criterion used in this paper is the identification in the limit proposed by Gold. Further, we use the tree pattern language to represent preconditions of operators, and propose a class of strategies, called decision list strategies. One of the interesting features of our learning algorithm is the coupled use of state and operator sequence information of traces. Theoretically, we show that the proposed algorithm identifies some subclass of decision list strategies in the limit with the conjectures updated in polynomial time. Further, an experimental result on N-puzzle domain is presented.

In this paper, we propose a new framework for global traffic control in ATM networks which aims to maximize resource utilization and to guarantee the reliable congestion control. To do this, we first propose Global Traffic Control (GTC) mechanism which is based on harmonious cooperation of each traffic control function. GTC measures real bandwidth utilization to compensate inaccuracy of the declared mean cell rate and it also monitors cell losses to manage input traffic load when a network approaches congestion state. We also propose new adaptive connection admission control (CAC) algorithms which calculate cell loss performance of related function blocks in a switch node using only a declared peak cell rate and an estimated mean cell rate. We measure only the mean cell rate of the aggregate cell stream in a link to estimate the mean cell rate of each virtual channel connection. We adopt a peak cell rate spacer at the User Network Interface (UNI) to compensate a cell delay variation (CDV). We will also present an approximation technique to estimate a queue length distribution of a general queue. As this technique requires negligible calculation time, it can meet the stringent requirement on the connection set-up time.

Complexity of Boolean functions satisfying the propagation criterion (PC), an extended notion of the perfect nonlinearity, is discussed on several computation models. The following topics are investigated: (i) relationships between the unateness and the degree of the PC, (ii) the inversion complexity of perfectly nonlinear Boolean functions, (iii) the formula size of Boolean functions that satisfy the PC of degree 1, (iv) the area-time-square complexity of VLSI circuits computing perfectly nonlinear Boolean functions, (v) the OBDD size perfectly nonlinear Boolean functions.