Modern video compression usually consists of ME/MC (Motion Estimation/Motion Compensation), transform, and quantization of the transform coefficients. Efficient bit allocation technique to distribute available bits to motion parameters and quantized coefficients is an important part of the whole system. A method that is very complex and/or needs buffering of many future frames is not suitable for real time application. We develop an efficient bit allocation technique that utilizes the estimated effect of allocated bits to motion parameter and quantization on the overall quality. We also propose an hierarchical block based ME/MC technique that requires less computations than classical BMA (Block Matching Algorithm) while offering better motion estimation.

A fully differential direct conversion receiver IC for W-CDMA is presented. The receiver IC consists of an LNA, a quadrature demodulator, low-pass filters (LPFs), and variable gain amplifiers (VGAs). In order to suppress DC offset, which is the most important issue in a direct conversion system, an active harmonic mixer is applied to the quadrature demodulator. Furthermore, a receiving system, including the LNA and an RF filter, adopts a differential architecture to reduce local signal leakage, which generates DC offset. Performance of the entire receiving system was evaluated and DC offset in steady state was measured at only 40 mV. Moreover, DC offset variation at the LNA gain change, which has the largest affect on the receiving performance, was limited to 70 mV, which is less than -10 dB compared to desired signal strength. It was confirmed by computer simulation that the DC offset variation at the LNA gain change did not degrade bit error rate (BER) performance at all.

This paper presents a new submesh allocation scheme for mesh connected multicomputer systems, called CFSL-TR (Classified Free Submesh List-Task Relocation), which reduces task waiting time in two aspects, shortening submesh search time and reducing the submesh allocation delay caused by external fragmentation. This scheme classifies independent free submeshes by their types: square, horizontal rectangle, or vertical rectangle. Then it searches for the best-fit submesh only from one list depending on the type of the given task, thus saving submesh searching time. If no suitable submeshes are found, it is most likely caused by external fragmentation. In such a case, our scheme relocates the tasks being executed to free submeshes and combines the newly available submesh with other fragmented ones to form a larger submesh. This allows allocation of the task, otherwise to be put on the queue, hence reducing the submesh allocation delay. Through simulation, we show that our scheme helps reduce task waiting time and that it is by far more effective to reduce the submesh allocation delay caused by external fragmentation rather than to reduce submesh search time for reduction of the task waiting time.

This letter shows the performance comparisons of several different rate scheduling schemes for non-real time data service over the uplink of burst switching-based direct sequence code division multiple access (DS/CDMA) system to support the integrated voice/data service. The closed-form solution of optimal scheduling formulation, which minimizes average transmission delay when all of the active data users are transmitting simultaneously, is presented and mathematical analyses with other rate scheduling schemes, which provide efficiency criterion of transmission delay for rate scheduling schemes, are performed. Numerical results show the analyses explicitly.

An automatic-repeat-request (ARQ) scheme for improving the system throughput efficiency is evaluated in coded multiple-input multiple-output (MIMO) transmissions. Supplementary trellis-coded modulation (TCM) code has been proposed for hybrid ARQ schemes. The free distance of the TCM after code combining can be increased by employing different TCM codes for retransmissions. The MIMO scheme offers additional flexibility in preventing successive frame errors by changing the connections between transmitters and transmit antennas upon retransmission. In this paper, an ARQ strategy employing both TCM reassignment and antenna permutation technique is investigated. It is shown through computer simulations that this ARQ scheme achieves high throughput even in severe conditions of low signal-to-noise ratio and high Rician factor over spatially and temporally correlated Nakagami-Rice fading MIMO channels.

We numerically and experimentally investigated the upgradability of the longest and the typical segments of the JIH system. Through these studies, we confirmed that a 100 GHz-spaced 25 42.7 Gbit/s transmission with the total capacity of 1 Tbit/s can be attainable even by using NRZ signal and standard FEC for the typical segments. We also found that RZ signal format was desirable for the longest segment and a further wide system margin could be expected by using adjacent channel polarization control and advanced FEC technologies.

In this paper, we consider QoS-guaranteed wavelength allocation for WDM networks with limited-range wavelength conversion. In the wavelength allocation, the pre-determined number of wavelengths are allocated to each QoS class depending on the required loss probability. Moreover, we consider two wavelength selection rules and three combinations of the rules. We analyze the connection loss probability of each QoS class for a single link using continuous-time Markov chain. We also investigate the connection loss probability for a uni-directional ring network by simulation. In numerical examples, we compare connection loss probabilities for three combinations of selection rules and show how each combination of selection rules affects the connection loss probability of each QoS class. Furthermore, we show how wavelength conversion capability affects the connection loss probability. It is shown that the proposed allocation with appropriate wavelength selection rule is effective for QoS provisioning when the number of wavelengths is large. We also show the effective combination of wavelength selection rules for the case with small wavelength conversion capability.

Uplink synchronous transmission has been proposed to improve the uplink capacity of DS-CDMA systems by means of canceling interference from the main paths of other intra-cell users. A significant capacity gain has been reported in a single cell environment. This Letter further investigates the uplink capacity in a multiple cell environment, where two crucial factors are taken into account, namely code shortage problem and soft handover. The impacts of the target Eb/Io and the other-to-own cell interference ratio, together with the number of channelisation codes, are discussed mathematically and then, confirmed through system level simulations with more realistic parameters.

An information retrieval (IR) system with query expansion on a low-cost high-performance PC cluster environment is implemented. We study how query performance is affected by query expansion and two declustering methods using two standard Korean test collections. According to the experiments, the greedy method shows about 20% enhancement overall when compared with the lexical method.

This paper presents the architecture and design of the video CODEC circuit that can compress and reconstruct 4:2:2 color VGA video images in real time. Our circuit is based on two-dimensional DWT and inter-frame compression technique. For low-power real-time operation, we modified the traditional Mallat's sub-band coding method to reduce the amount of computation and memory access required in two-dimensional DWT. We also incorporated inter-frame compression technique into our CODEC circuit to enhance the compression capability. To avoid an intensive computation required in motion detection, we encoded only the macro blocks in the current frame which are different from those in the same location of the previous frame to exploit the fact that the background image does not change much in DVR system. We fabricated the CODEC chip using 0.35 µm 3.3 V CMOS standard cell process and applied it to the 16-channel DVR security system.

The present paper proposes differential transmission line structures on Si ULSI. Interconnect structures are examined using numerical results from a two-dimensional electromagnetic simulation (Ansoft, 2D Extractor). The co-planar and diagonal-pair lines are found to have superior characteristics for gigahertz signal propagation through long interconnects. The proposed diagonal-pair line can reduce the crosstalk noise and interconnect resource concurrently.

This paper proposes a novel method of identifying the design parameters for a practical implementation of the fair queueing discipline, which is capable of class-level delay control. The notion of class weight is introduced at first, and then the session weights are determined. This two-phase approach is favorable in terms of the scalability;that is, the overall complexity is dependent upon the number of classes only. We propose a packet scheduler referred to as the DPS (Delay-centric Processor Sharing) scheme which employs those design parameters to deliver class-wise delay bound services. The associated admission policy for delay guarantee is also derived. System analysis and derivation of the parameters have their origins in the understanding of the so-called system equation, which describes the dynamics of the class-level service share. The proposed design parameters are QoS-aware in that they are consistently refined depending on the system status. Several numerical and simulation results show that the DPS scheme is advantageous over other ones in terms of both resource efficiency and the robustness. Concerning the scalability, we show that an alternative tagging process of the DPS scheme is implementable with O(1) complexity with no significant degradation in delay performance.

There have been many researches on indexing and querying XML data. One of the important themes is how to efficiently process XML query represented by path expression. The most straightforward approach to process these queries is to traverse the hierarchy of XML document by top-down or bottom-up manner. However it may be fairly inefficient because the overhead of traversing the XML data can be high. In addition, most of the proposed indexing and retrieval schemes assume static environment where there are no updates on the parts of XML data. In this paper we propose a novel indexing and query processing scheme that can process both XML query represented by path expression efficiently and dynamic updates on XML data promptly. Experimental results show that our proposed scheme achieves better performance than that of the previous ones.

As the Internet proliferates, there has been a growing interest in supporting multiparty collaborative applications. It has led to the emergence of many-to-ma ny reliable multicast. Congestion control is a key task in reliable multicast along with error control. However, existing tree-based congestion control schemes such as TRAMCC and MTCP are designed for one-to-many reliable multicast and have some drawbacks when they are used for many-to-many reliable multicast. We propose an efficient congestion control mechanism, MTRMCC, for tree-based many-to-many reliable multicast protocols. The proposed scheme is based on the congestion windowing mechanism and a rate controller is used in addition. The feedback for error recovery is exploited for congestion control as well to minimize the overhead at the receivers. The ACK timer and the NACK timers are set dynamically reflecting the network traffic changes. The rate regulation algorithm in the proposed scheme is designed to help the flows sharing the same link to achieve the fair share quickly. The performance of the proposed scheme is evaluated using network simulator ns-2. The simulation results show that the proposed scheme outperforms TRAMCC in terms of intra-session fairness and supports responsiveness, TCP-friendliness, and scalability.

In this paper we give the necessary and sufficient conditions for 2-dimensional discrete-time systems described by the signum function to be stable.

This paper deals with the method for generation of maximal-period sequences which are designed by properly quantizing the variable state of a class of one-dimensional piecewise-linear onto maps. We confirmed that the proposed method enables us to generate many maximal-period sequences from such maps including De-Bruijn cases.

In order to perform the registration of virtual objects in vision-based augmented reality systems, the estimation of the relation between the real and virtual worlds is needed. This paper presents a three-point vision-based registration method for video see-through augmented reality systems using binocular cameras. The proposed registration method is based on a combination of monocular and stereoscopic registration methods. A correction method that performs an optimization of the registration by correcting the 2D positions in the images of the marker feature points is proposed. Also, an extraction strategy based on color information is put forward to allow the system to be robust to fast user's motion. In addition, a quantification method is used in order to evaluate the stability of the produced registration. Timing and stability results are presented. The proposed registration method is proven to be more stable than the standard stereoscopic registration method and to be independent of the distance. Even when the user moves quickly, our developed system succeeds in producing stable three-point based registration. Therefore, our proposed methods can be considered as interesting alternatives to produce the registration in binocular augmented reality systems when only three points are available.

Recent growth in computer communications has led to an increased requirement for high-speed backbone networks. In such high-speed networks, the principle adopted for a time-sensitive flow control mechanism should be that of autonomous decentralized control. In this mechanism, each node in a network manages its local traffic flow only on the basis of the local information directly available to it, although it is desirable that the individual decisions made at each node lead to high performance of the network as a whole. In our previous studies, we have investigated the behavior of local packet flows and the global performance achieved when a node is congested, and proposed the diffusion-type flow control model. However, since we used a simple and homogeneous network model in the evaluation, the results cannot be generalized. In this paper, we propose an extension of the diffusion-type flow control model in order to apply it to networks with inhomogeneous configurations. We show simulation results for two cases: different propagation delays and multiple bottlenecks. Both results show that the proposed diffusion-type flow control achieves high and stable performance even if the network is congested.

In story-based communication, where a message is conveyed in story form, it is important to embody the story with expressive materials. However, it is quite difficult for users to create rich multimedia contents using multimedia editing tools. This paper proposes a web-based multimedia environment, SPOC (Stream-oriented Public Opinion Channel), aiming at helping non-skillful people to convert their stories into TV-like programs very easily. The system can produce a digital camera work for graphics and video clips as well as generate an agent animation automatically according to a narration text. Findings in evaluation experiments showed that SPOC is easy-to-use and easy-to-learn for novice users. Given a short instruction, the subjects not only mastered the operations of the software, but also succeeded in creating highly original programs. In subjective evaluation, the subjects answered that they enjoyed using the software without feeling difficulty. These results suggest that this system reduces user's cost in making a program, and encourages communication in a network community.

This paper proposes a novel feature selection method for the fuzzy neural networks and presents an application example for 'personalized' facial expression recognition. The proposed method is shown to result in a superior performance than many existing approaches.