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.

Optical path technology that employs both WDM/FDM and wavelength routing will play a key role in supporting future high bandwidth transport networks. WP/VWP (Wavelength Path/Virtual Wavelength Path) technologies are very effective in realizing optical path networks. In these networks, since photonic wavelengths are scarce resources, the number of wavelengths required to construct the network must be minimized. However, the wavelength assignment problem, minimizing the number of wavelengths, is an NP-complete problem. Solving this problem heuristically is an important issue for designing large-scale WP/VWP based networks that are also practical. To realize optical path networks, we need to develop path accommodation design algorithms that heuristically solve the wavelength assignment problem. This paper proposes novel path accommodation design algorithms for WP/VWP networks that minimize the number of wavelengths required. We numerically elucidate that the numbers of wavelengths required for active WPs and VWPs are almost equal. When link failure restoration is considered, they are different; more wavelengths are needed with the WP scheme than with the VWP scheme. It is also demonstrated that the proposed algorithms are applicable to a large scale network design.

A new gloss-extracting method is proposed in this study. A spatial filter with variable resolution is used for the extraction of glossiness. Various spheres and cylinders with curvature radii from 4 to mm are used as the specimens. In all samples, a strong correlation, with a correlation coefficient of more than 0.98, has been observed between psychological glossiness Gph perceived by the human eye and glossiness Gfm extracted by this method. This method is useful for plane specimens as well as spherical and cylindrical ones.

A key element in the CDMA transmission is DS spreading. Spreading in a DS/SSMA system are provided in two categories-synchronization and data. For synchronization sequences, good auto-correlation and cross-correlation properties are required in order to guarantee fast acquistion with a minimum false alarm probability. On the other hand, the auto-correlation property may not be so important in data spreading since synchronization is obtained by synchronization spreading. In this paper we provide a set of synchronization sequences and a set of data sequences--each a set of binary N-tuples--that have the necessary correlation constraints.

We describe an application of InGaAs/AlGaAs VCSELs to multiple wavelength light source for optical interconnection. A flip-chip bonding technique is used to integrate the VCSELs lasing at different wavelengths. The integrated VCSELs of different wavelengths are individually grown and processed, so that one can optimize the device characteristics and the wavelength separation or distribution for multiple wavelength interconnection systems. A 9-wavelength VCSEL array with a wavelength separation of 5 nm has been successfully fabricated.

Wavelength-division multiplexing (WDM) optical switching networks are one of most attractive technologies in optical interconnections. By combining with time-division multiplexing (TDM) and space-division multiplexing (SDM) technologies, remarkably high-throughput interconnections may be accomplished. In this paper, we propose WDM switching networks with time-division multiplexed optical signals by using free-space optics. We also propose novel WDM interconnections, including multiple-wavelength light-sources, optical fibers and wavelength-selectable detectors. We successfully confirmed basic principles for the WDM interconnections.

This paper describes an adaptively weighted code division multiplexing (AW-CDM) system, in other words, power controlled spread-spectrum multiplexing system and describes its application to hierarchical digital broadcasting of television signals. The AW-CDM, being combined with multi-resolutional video encoder, can provide such a hierarchical transmission that allows both high quality services for fixed receivers and reduced quality services for mobile/portable receivers. The carrier and the clock are robustly regenerated by using a spread-spectrum multiplexed pseudorandom noise (PN) sounder as a reference in the receiver. The PN reference is also used for Rake combining with signals via different paths, and for adaptive equalization (EQ). In a prototype AW-CDM modem, three layers of hierarchical video signals (highs: 5.91Mbps, middles: 1.50Mbps, and lows: 0.46 Mbps) are divided into a pair of 64 orthogonal spread-spectrum subchannels, each of which can be given a different priority and therefore a different threshold. In this case, three different thresholds are given. The modem's transmission rate is 9.7Mbps in the 6MHz band. Indoor transmission tests confirm that lows (weighted power layer I), middles (averaged power layer II), and highs (lightened power layer III) are retrievable under conditions in which the desired to undesired signal ratios (DURs) are respectively 0dB, 8.5dB, and 13.5dB. If the undesired signals are multipaths, these performances are dramatically improved by Rake combining and EQ. The AW-CDM system can be used for 20-30 Mbps advanced television (ATV) transmission in the 6-MHz bandwidth simply by changing the binary inputs into quaternary or octonary inputs.

The current state of development of the television broadcasting system of the future is described with regard to LSI development. It is no need to say that television broadcasting systems are very huge and require a large number of inexpensive LSI's. Hi-Vision broadcasting has already been started in Japan. In the United States, a digital terrestrial broadcasting system (ATV) will be standardized in the near future. On the other hand, the situation in Europe remains unclear but MPEG-2 is now in the stage of system finarizing. We also hear much about "multimedia" but the concept of multimedia broadcasting still requires a lot of time to be translated into reality. Some important current technical topics and related basic technologies are also described in this paper. They include DCT, Hybrid DCT coding, error correcting coding, coded modulation, and improvement of the MUSE system. Finally, the discussion considers the relationship between system development and VLSI technology and the importance of mutual understanding between VLSI engineers and system designers. Some possible requirements for VLSI development are also stated.

We prove that the maximum likelihood estimator for estimating 3-D motion from noisy optical flow is not optimal", i.e., there is an unbiased estimator whose covariance matrix is smaller than that of the maximum likelihood estimator when a Gaussian noise distribution is assumed for a sufficiently large number of observed points. Since Gaussian assumption for the noise is given, the maximum likelihood estimator minimizes the mean square error of the observed optical flow. Though the maximum likehood estimator's covariance matrix usually reaches the Cramér-Rao lower bound in many statistical problems when the number of observed points is infinitely large, we show that the maximum likelihood estimator's covariance matrix does not reach the Cramér-Rao lower bound for the estimation of 3-D motion from noisy optical flow under such conditions. We formulate a superior estimator, whose covariance matrix is smaller than that of the maximum likelihood estimator, when the variance of the Gaussian noise is not very small.

Experimental optical gain characteristics of an erbium-doped fiber amplifier have not been explained well by conventional laser schemes in the case of two-channel amplification. Modified simple laser schemes including cross relaxation among degenerate levels were valid for the explanation of the optical gain dependence on input signal power and on the erbium-doped fiber length.

Different signature codes in an optical code division multiple access (CDMA) network have been known to demonstrate different performances. The performance of different signature codes in an optical CDMA network was analyzed here in this paper by including the performance evaluation for the synchronization process which was not considered previously. Both auto- and cross-correlation properties of the signature codes were found to be important. In addition, the performance comparison of (n, w1, 1, 1), (n, w2, 2, 1) optical orthogonal codes (OOC's), and (n, w3, w3, 1) extended prime code demonstrated that an (n, w2, 2, 1) OOC could accommodate more users than the other two.

Creating a bandwidth abundant B-ISDN requires the further development of path technologies. Optical path cross-connect nodes (OXCs) will be required that offer very high levels of expandability. The present limited traffic demands must be efficiently supported while permitting easy step-wise expansion in capacity. This paper proposes two OXC architectures that offer high modularity with regard to incoming/outgoing links or the number of multiplexed wavelengths in each link. This paper briefly reviews, for optical path realization, the wavelength path (WP) and the virtual wavelength path (VWP) techniques. The proposed OXC architectures provide flexibility and minimum investment to encourage introduction but support incremental network growth and investment to match traffic demand. The architectures make it easy to upgrade a WP network to a VWP network, simply by replacing some optical components. It is also shown that the proposed OXC architectures ensure effective optical signal detection after a long-haul optical fiber transmission because they minimizes signal power losses within the OXC. Therefore, the proposed OXC architecture can be applied to global area networks. The proposed OXC architectures will play a key role in realizing the optical path infrastructure for the future bandwidth abundant B-ISDN.

This paper describes a noise resistant algorithm for estimating 3-D rigid motion from optical flow. We first discuss the problem of constructing the objective function to be minimized. If a Gaussian distribution is assumed for the niose, it is well-known that the least-squares minimization becomes the maximum likelihood estimation. However, the use of this objective function makes the minimization procedure more expensive because the program has to go through all the points in the image at each iteration. We therefore introduce an objective function that provides unbiased estimators. Using this function reduces computational costs. Furthermore, since good approximations can be analytically obtained for the function, using them as an initial guess we can apply an iterative minimization method to the function, which is expected to be stable. The effectiveness of this method is demonstrated by computer simulation.

In this paper, we first discuss on a framework for a 3D image display system which is the combination of passive sensing and active display technologies. The passive sensing enables to capture real scenes under natural condition. The active display enables to present arbitrary views with proper motion parallax following the observer's motion. The requirements of passive sensing technology for 3D image displays are discussed in comparison with those for robot vision. Then, a new stereo algorithm, called SEA (Stereo by Eye Array), which satisfies the requirements is described in detail. The SEA uses nine images captured by a 33 camera array. It has the following features for depth estimation: 1) Pixel-based correspondence search enables to obtain a dense and high-spatial-resolution depth map. 2) Correspondence ambiguity for linear edges with the orientation parallel to a particular baseline is eliminated by using multiple baselines with different orientations. 3) Occlusion can be easily detected and an occlusion-free depth map with sharp object boundaries is generated. The feasibility of the SEA is demonstrated by experiments by using real image data.

We can understand and recover a scene even from a picture or a line drawing. A number of methods have been developed for solving this problem. They have scarcely aimed to deal with scenes of multiple objects although they have ability to recognize three-dimensional shapes of every object. In this paper, challenging to solve this problem, we describe a method for deciding configurations of multiple objects. This method employs the assumption of coplanarity and the constraint of occlusion. The assumption of coplanarity generates the candidates of configurations of multiple objects and the constraint of occlusion prunes impossible configurations. By combining this method with a method of shape recovery for individual objects, we have implemented a system acquirig a three-dimensional information of scene including multiple objects from a monocular image.

Mode separation of a multiplex mode in a mode-division multiplexing system is studied. The clear, desired single-mode pattern, which is separated from the multiplex mode by using a holographic filter, is observed in the experiment.

The paper describes the architecture and the simulated performances of a memory-based chip that emulates human cortical processing in early visual tasks, such as texture segregation. The featural elements present in an image are extracted by a convolution block and subsequently processed by the cortical chip, whose neurons, organized into three layers, gain relational descriptions (intelligent processing) through recurrent inhibitory/excitatory interactions between both inter-and intra-layer parallel pathways. The digital implementation of this architecuture directly maps the set of equations determining the status of the cortical network to achieve an optimal exploitation of VLSI technology in neural computation. Neurons are mapped into a memory matrix whose elements are updated through a programmable computational unit that implements synaptic interconnections. By using 0.5 µm-CMOS technology, full cortical image processing can be attained on a single chip (2020 mm2 die) at a rate higher than 70 frames/second, for images of 256256 pixels.

An approach to estimate the information of moving objects is described in terms of their kinetic and static properties such as 2D velocity, acceleration, position, and the size of each object for the features of motion snd shape. To obtain the information of motion/shape of multiple objects, an advanced contour matching scheme is developed, which includes the synthesis of edge images and the analysis of object shape with a high matching confidence as well as a low computation cost. The scheme is composed of three algorithms: a motion estimation by an iterative triple cross-correlation, an image synthesis by shifting and masking the object, and a shape analysis for determining the object size. Implementing fuzzy membership functions to the object shape, the scheme gets improved in accuracy of capturing motion and shape of multiple moving objects. Experimental result shows that the proposed method is valid for several walking men in real scene.

This paper studies the effect of frequency re-using patterns on the channel capacity in the forward link of orthogonal code division multiple access (CDMA) cellular systems. The received carrier-to-interference ratio (CIR) determined by computer simulation shows that re-using the same frequency channel on every third sector (3-sector layout) provides superior channel capacity than does every-sector re-use (1-sector layout).

This paper proposes a new method to determine the shape of a surface by learning the mapping between three image irradiances observed under illumination from three lighting directions and the corresponding surface gradient. The method uses Phong reflectance function to describe specular reflectance. Lambertian reflectance is included as a special case. A neural network is constructed to estimate the values of reflectance parameters and the object surface gradient distribution under the assumption that the values of reflectance parameters are not known in advance. The method reconstructs the surface gradient distribution after determining the values of reflectance parameters of a test object using two step neural network which consists of one to extract two gradient parameters from three image irradiances and its inverse one. The effectiveness of this proposed neural network is confirmed by computer simulations and by experiment with a real object.