This paper presents a performance comparison between the single-stream and the multi-stream approaches to lip synchronization of live media (voice and video). The former transmits a single transport stream of interleaved voice and video, while the latter treats the two media as separate transport streams. Each approach has an option not to exert the synchronization control at the destination, which leads to four basic schemes. On an interconnected ATM-wireless LAN, we implemented the four basic schemes with RTP/RTCP on top of UDP and two variants which exercise dynamic resolution control of JPEG video. Making the performance measurement of the six schemes, we compare them to identify and evaluate advantages and disadvantages of each approach. We then show that the performance difference between the two approaches is small and that the dynamic resolution control improves the synchronization quality.

Space Division Multiple Access (SDMA) will form an important part of the new Wideband Code Division Multiple Access (WCDMA) standard that will realize the Universal Mobile Telephone System (UMTS). This paper addresses a few issues of importance when SDMA techniques are used in a cellular CDMA system. Firstly, a brief overview of SDMA techniques are presented followed by a theoretical analysis of a SDMA/CDMA system. The analysis is focused on a single cell, multipath Rayleigh fading scenario with imperfect power control. As system performance measure Bit Error Rate (BER) is used to investigate the influence of user location, number of antennas and power control error. An important parameter in a SDMA system is the antenna array element spacing. In our analysis a Uniform Linear Array (ULA) is considered and a measure is defined to determine the optimal antenna element spacing in a CDMA cellular environment. Normally the mobile users in a cell are assumed to be uniformly distributed in cellular performance calculations. To reflect a more realistic situation, we propose a novel probability density function for the non-uniform distribution of the mobile users in the cell. It is shown that multipath and imperfect power control, even with antenna arrays, reduces the system performance substantially.

The slope of transient waveform is dominated by the characteristics of the discharging (or charging) path, including the path topology, the sizes and the states of MOS transistors. The slope value of transient waveform can be obtained by calculating the equivalent RC time constant of the evaluated cluster circuit, and it can be obtained efficiently by traversing the tree recursively. However, bottleneck effect always exists in the charging/discharging path and plays an important role on the charging/discharging behavior of the output. If neglect the effect, the waveform approximation technique used in BTS will give rise to a larger error in some cases. Therefore, we propose an algorithm to solve this problem.

This paper describes key techniques for automatic program generation of office data handling for all types of switching systems. Our office data scenario tool generates logical-physical office data conversion programs to be installed in switching systems. Also, it generates logical office data generation programs to be installed in a logical office data generation tool that converts office conditions to a logical office data file. We were able to apply this tool to all the office data types for our new switching systems, and automatically generated about 5. 5% of the total program size. This technique reduces not only the software production cost but also the bug ratio because there is no room for human error. Also, switching system programs are much more portable, since no machine-code-dependent parts are involved in office data handling. Thus, we expect that these techniques will be the basis for highly productive, reliable, and portable software platforms for the next-generation multimedia communication systems.

A new numerical procedure called asymptotic periodic waveform evaluation (APWE) for finding the steady state solution of nonlinear circuits driven by one tone periodic input signal is presented. APWE starts by constructing a virtual system which gives the same periodic steady state waveform as the original system's but with a shorter transient duration. Thus the periodic steady state (PSS) response can be obtained by simply performing transient analysis of the newly derived system for a few periods. An efficient method for solving the nonlinear equations occurred during the transient analysis is presented. To improve the convergence rate of PSS waveform, APWE is combined with extrapolation method. Some simulation results are shown.

It is urgently required to protect copyrights of digital contents since the digital contents can be easily copied without degradation of quality. In this paper, we propose a new watermarking method which spreads an ID pattern with a random sequence and embeds it throughout the spatial domain of a color image. The random sequence is a key for extracting the ID pattern. As an ID pattern is spread throughout an image, we can extract the ID pattern from a part of the image, that is clipped image. We can also confirm authenticity by extracting the same ID pattern from several parts of an image. The proposed method is robust to disturbance by noise addition and image conversion such as brightness-contrast conversion and JPEG compression.

Video on demand is regarded as one of the most important applications in future broadband networks. Although several trial runs in various parts of the world do not bring instant success, its inherent requirements for bandwidth and bounded delay make it a suitable candidate for studying various networks and protocols in real-time applications. Recently, the Hybrid Fiber Coaxial (HFC) networks emerged as network architecture for bringing broadband services to the home. The co-axial cable network uses a tree-like architecture and requires complex protocols for synchronizing and sharing uplink communications among many users. This paper proposes that a dual bus network may be a simpler and cost effective alternative. We implement an interactive VOD (IVOD) system as an example to demonstrate its simplicity and suitability as a community network. The system uses client/server architecture with guaranteed bandwidth and bounded delays. Simulations are conducted to test the network load and response time for different number of users. The results indicate its feasibility and the delay time can be further reduced by releasing bandwidth during the pause operation.

In order to lessen overflow or underflow problem in numerical computation, several new floating-point arithmetics have been proposed. The significant advantage of these new arithmetics is that a number can be represented in a wider range since the fields of exponent and mantissa are changed depending on the magnitude of number. The main issues of these arithmetics are how to find the boundary between exponent and mantissa as well as to convert the formats between new floating-point arithmetic and fixed-point arithmetic quickly. In this paper, a CAM-based array converter based on the Universal Representation of Real number (URR) floating-point arithmetic is described. Using match retrieval device CAM, the detection of the boundary can be accomplished faster than conventional circuits. Arranging the basic cells into iterative array structure, the fast separation/connection operation is achieved. The speed, area and power consumption of the converter is estimated.

We propose an information integration architecture for a man-machine interface to construct a new agent-based Computer Supported Cooperative Work (CSCW) system. The system acts as a clerk in cooperative work giving users the advantage of using cooperative work space. The system allows users to do their work in the style of an ordinary meeting because spontaneous expressions of speech and gestures by users are detected by sensors so that they can be integrated with a task model at several levels to create suitable responses in a man-machine interface. As a result, users can dedicate themselves to mutually understand other meeting members with no awareness of direction to the CSCW system. In this paper, we describe the whole system and its information integration architecture for the man-machine interface including, the principle of functions, the current status of the system and future directions.

This paper presents both new analytical and new numerical solutions to the problem of generating waveforms exhibiting a low peak-to-peak factor. One important application of these results is in the generation of pseudo-white noise signals that are commonly uses in multi-frequency measurements. These measurements often require maximum signal-to-noise ratio while maintaining the lowest peak-to-peak excursion. The new synthesis scheme introduced in this paper uses the Discrete Fourier Transform (DFT) to generate pseudo-white noise sequence that theoretically has a minimized peak-to-peak factor, Fp-p. Unlike theoretical works in the literature, the method presented here is based in purely discrete mathematics, and hence is directly applicable to the digital synthesis of signals. With this method the shape of the signal can be controlled with about N parameters given N harmonic components. A different permutation of the same set of offset phases of the "source harmonics" creates an entirely different sequence.

This paper proposes an object oriented face region detection and tracking method using range color information. Range segmentation of the objects are obtained from the complicated background using disparity histogram (DH). The facial regions among the range segmented objects are detected using skin-color transform technique that provides a facial region enhanced gray-level image. Computationally efficient matching pixel count (MPC) disparity measure is introduced to enhance the matching accuracy by removing the effect of the unexpected noise in the boundary region. Redundancy operations inherent in the area-based matching operation are removed to enhance the processing speed. For the skin-color transformation, the generalized facial color distribution (GFCD) is modeled by 2D Gaussian function in a normalized color space. Disparity difference histogram (DDH) concept from two consecutive frames is introduced to estimate the range information effectively. Detailed geometrical analysis provides exact variation of range information of moving object. The experimental results show that the proposed algorithm works well in various environments, at a rate of 1 frame per second with 512 480 resolution in general purpose workstation.

This paper proposes a new method for dynamically controlling the clock speed of a processor in order to reduce power consumption without decreasing system performance. It automatically tunes the processor's speed by monitoring its activities and avoiding useless work so as not to exhaust the battery energy. Experiments with performance bottlenecks caused by disk activities show that the proposed method is very effective in comparison with the traditional one, in which the processor's speed is fixed.

This paper describes methods of tracking of moving objects in a cluttered background by integrating optical flow, depth data, and/or uniform brightness regions. First, a basic method is introduced which extracts a region with uniform optical flow as the target region. Then an extended method is described in which optical flow and depth are fused. A target region is extracted by Baysian inference in term of optical flow, depth and the predicted target location. This method works only for textured objects because optical flow or depth are extracted for textured objects. In order to solve this problem, uniform regions in addition to the optical flow are used for tracking. Realtime human tracking is realized for real image sequences by using a real time processor with multiple DSPs.

We introduce an image contour clustering method based on a multiscale image representation and its application to image compression. Multiscale gradient planes are obtained from the mean squared sum of 2D wavelet transform of an image. The decay on the multiscale gradient planes across scales depends on the Lipshitz exponent. Since the Lipshitz exponent indicates the spatial differentiability of an image, the multiscale gradient planes represent smoothness or sharpness around edges on image contours. We apply vector quatization to the multiscale gradient planes at contours, and cluster the contours in terms of represntative vectors in VQ. Since the multiscale gradient planes indicate the Lipshitz exponents, the image contours are clustered according to its gradients and Lipshitz exponents. Moreover, we present an image recovery algorithm to the multiscale gradient planes, and we achieve the skech-based image compression by the vector quantization on the multiscale gradient planes.

In this paper, we study the optimal allocation of multimedia files in distributed network systems. In these systems, the files are shared by users connected with different servers geographically separated, and each file must be stored in at least one of servers. Users can access any files stored in any servers connected with high-speed communication networks. Copies of the files accessed frequently are to be stored in several servers that have databases. So, it is one of the most important problems how to assign the files to servers in view of costs and delays. Considering these problems in heterogeneous network environments, we present a new system model that covers wide range of multimedia network applications like VOD, CALS, and so on. In these systems, it is obvious that there is trading-off relationship between costs and delays. Our objective is to find the optimal file allocation such that the total cost is minimized subject to the total delay. We introduce a 0-1 integer programming formulation for the optimization problem, and find the optimal file allocation by solving these formulae.

In this paper, the performances of texture classification based on pyramidal and uniform decomposition are comparatively studied with and without feature selection. This comparison using the subband variance as feature explores the dependence among features. It is shown that the main problem when employing 2-D non-separable wavelet transforms for texture classification is the determination of the suitable features that yields the best classification results. A Max-Max algorithm which is a novel evaluation function based on genetic algorithms is presented to evaluate the classification performance of each subset of selected features. It is shown that the performance with feature selection in which only about half of features are selected is comparable to that without feature selection. Moreover, the discriminatory characteristics of texture spread more in low-pass bands and the features extracted from the pyramidal decomposition are more representative than those from the uniform decomposition. Experimental results have verified the selectivity of the proposed approach and its texture capturing characteristics.

Adaptive estimation of nonstationary sinusoidal signals or quasi-periodic signals in additive noise is of essential importance in many diverse engineering fields, such as communications, biomedical engineering, power systems, pitch detection in transcription and so forth. So far, Kalman filtering based techniques, recursive least square (RLS), simplified RLS (SRLS) and LMS algorithms, for examples, have been developed for this purpose. This work presents in detail a performance analysis for the SRLS algorithm proposed recently in the literature, which is used to estimate an enhanced sinusoid. Its dynamic and tracking properties, noise and lag misadjustments are developed and discussed. It is found that the SRLS estimator is biased, and its misadjustments are functions of not only the noise variance but also, unpleasantly, of the signal parameters. Simulations demonstrate the validity of the analysis. Application of the SRLS to a real-life piano sound is also given to peek at its effectiveness.

Evaluating analytically computer architecture performance is mostly cheap and quick. However, existing analytical performance evaluation techniques usually have a difficult and time-consuming modeling process. Moreover, existing techniques do not support well the capability for finding the bottleneck and its cause of a target system being evaluated. To address the above problems and to enhance analytical performance evaluation technology, in this paper we propose a software tool that accepts system models described in a specification language, generating an executable program that performs the actual performance evaluation. The whole approach is built on a subsystem-oriented performance evaluation tool, which is, in turn, based on a formal subsystem-oriented performance evaluation technique and a subsystem specification language.

The paper obtains an algorithm to estimate the irregular sampling in wavelet subspaces. Compared to our former work on the problem, the new estimate is relaxed for some wavelet subspaces.

A constant modulus adaptive array algorithm is derived using analysis and synthesis filter banks to permit adaptive digital beamforming for wideband signals. The properties of the CMA adaptive array using the filter banks are investigated. This array would be used to realize adaptive digital beamforming when this is difficult by means of ordinary (that is, non-subband) processing due to the limited speed of signal processor operations. As an actual application, we present a beamspace adaptive array structure that combines the analysis and synthesis filter banks with RF-domain multibeam array antennas, such as those utilizing optical signal processing.