The current Internet does not offer any quality of service guarantees or support to Internet multimedia applications such as Internet telephony and video-conferencing, due to the best-effort nature of the Internet. Their performance may be adversely affected by network congestion. Also, since these applications commonly employ the UDP transport protocol, which lacks congestion control mechanisms, they may severely overload the network and starve other applications. We present an overview of recent research efforts in developing adaptive delivery models for Internet multimedia applications, which dynamically adjust the transmission rate according to network conditions. We classify the approaches used to develop adaptive delivery models with brief descriptions of representative research work. We then evaluate the approaches based on important design issues and performance criteria, such as the scalability of the control mechanism, responsiveness in detecting and reacting to congestion, and ability to accommodate receiver heterogeniety. Some conclusions are developed regarding the suitability of particular design choices under various conditions.

This paper proposes a new distributed connection establishment scheme involving several competing network providers in a multimedia telecommunications environment. This connection establishment scheme, which is based on the concept of open competitive bidding, enables mutual selection by users and network providers. By employing this proposed scheme, both network providers and users can pursue their own objectives, according to their own bidding and awarding strategies. In this paper, a simple bidding strategy for network providers is presented, and the effectiveness of this strategy is evaluated by means of computer simulation. It is shown that each network provider can improve its profit by adopting this strategy. In this paper, an example of utility functions for users is presented, and the effectiveness of the mechanism with which users can select a network provider is also evaluated by means of computer simulation. Each user can improve his/her utility by selecting an appropriate network provider based on this utility function.

This paper discusses the classification of targets buried in the underground by radar polarimetry. The subsurface radar is used for the detection of objects buried beneath the ground surface, such as gas pipes, cables and cavities, or in archeological exploration operation. In addition to target echo, the subsurface radar receives various other echoes, because the underground is inhomogeneous medium. Therefore, the subsurface radar needs to distinguish these echoes. In order to enhance the discrimination capability, we first applied the polarization anisotropy coefficient to distinguish echoes from isotropic targets (plate, sphere) versus anisotropic targets (wire, pipe). It is straightforward to find the man-made target buried in the underground using the polarization anisotropy coefficient. Second, we tried to classify targets using the polarimetric signature approach, in which the characteristic polarization state provides the orientation angle of an anisotropic target. All of these values contribute to the classification of a target. Field experiments using an ultra-wideband (250 MHz to 1 GHz) FM-CW polarimetric radar system were carried out to show the usefulness of radar polarimetry. In this paper, several detection and classification results are demonstrated. It is shown that these techniques improve the detection capability of buried target considerably.

After a brief discussion of the demands in meshing for semiconductor process and device simulation, we present a three-dimensional Delaunay refinement technique combined with a modified advancing front algorithm.

Even though information in ATM networks is handled as fixed-sized packets (cells), packet-based scheduling is still needed in ATM networks. This letter proposes a packet-based scheduling mechanism that is based on comparison between a packet-based queue and a virtual queue that represents the queue length provided by a cell-based scheduling mechanism. Simulation results showed that this proposed scheduling allocates the bandwidth fairly to each connection.

The full-band Monte Carlo technique is currently the most accurate device simulation method, but its usefulness is limited because it is very CPU intensive. This work describes efficient algorithms in detail, which raise the efficiency of the full-band Monte Carlo method to a level where it becomes applicable in the device design process beyond exemplary simulations. The k-space is discretized with a nonuniform tetrahedral grid, which minimizes the discretization error of the linear energy interpolation and memory requirements. A consistent discretization of the inverse mass tensor is utilized to formulate efficient transport parameter estimators. Particle scattering is modeled in such a way that a very fast rejection technique can be used for the generation of the final state eliminating the main cause of the inefficiency of full-band Monte Carlo simulations. The developed full-band Monte Carlo simulator is highly efficient. For example, in conjunction with the nonself-consistent simulation technique CPU times of a few CPU minutes per bias point are achieved for substrate current calculations. Self-consistent calculations of the drain current of a 60nm-NMOSFET take about a few CPU hours demonstrating the feasibility of full-band Monte Carlo simulations.

This paper outlines the modeling requirements of integrated circuit (IC) fabrication processes that have lead to and sustained the development of computer-aided design of technology (i. e. TCAD). Over a period spanning more than two decades the importance of TCAD modeling and the complexity of required models has grown steadily. The paper also illustrates typical applications where TCAD has been powerful and strategic to IC scaling of processes. Finally, the future issues of atomic-scale modeling and the need for an hierarchical approach to capture and use such detailed information at higher levels of simulation are discussed.

The transfer function of IIR all-pass filters is a rational function of ω. However, the optimization of such a rational function using the successive projections method, which has a wider range of application than the Remez algorithm, has not been presented. In this paper, we propose designing IIR all-pass filters using the successive projections method.

IP multicast is very useful mechanism to deliver data to a large number of receivers such as interactive multimedia sessions. It can not accommodate the heterogeneity of the receivers including network heterogeneity. We propose a multicast traffic controller(s) in a router to solve such situation. A traffic controller has a filter to moderate the output data rate to a link. It makes use of Time-to-Live (TTL) threshold to specify the minimum requirement of a packet. Multimedia data are encoded into multiple layers; basic layer and enhanced layers. By associating TTLs of data layers and the threshold of the filter, we can moderate the traffic by dropping the data of less significant layer. The threshold is dynamically modified according to the local network traffic and link traffic. Our scheme also helps a network and a link(s) avoid from congestion and accommodate other types of traffic at the same time.

The architecture and control procedure for a direct conversion receiver are investigated for a linear modulation scheme. The proposed design techniques maintain receiver linearity despite various types of signal distortion. The techniques include the fast gain control procedure for receiving a control channel for air interface connection, DC offset canceling in both analog and digital stages, and 2nd-order intermodulation distortion canceling in an analog down-conversion stage. Experimental and computer simulation results on PHS (Personal Handy-phone System) parameters, showed that required linear modulation performance was achieved and thus the applicability of the proposed techniques was demonstrated.

A novel combinatorial optimization algorithm called "Gradual neural network (GNN)" is presented for NP-complete broadcast scheduling problems in packet radio (PR) networks. A PR network provides data communications services to a set of geographically distributed nodes through a common radio channel. A time division multiple access (TDMA) protocol is adopted for conflict-free communications, where packets are transmitted in repetition of fixed-length time-slots called a TDMA cycle. Given a PR network, the goal of GNN is to find a TDMA cycle with the minimum delay time for each node to broadcast packets. GNN for the N-node-M-slot TDMA cycle problem consists of a neural network with N M binary neurons and a gradual expansion scheme. The neural network not only satisfies the constraints but also maximizes transmissions by two energy functions, whereas the gradual expansion scheme minimizes the cycle length by gradually expanding the size of the neural network. The performance is evaluated through extensive simulations in benchmark instances and in geometric graph instances with up to 1000 vertices, where GNN always finds better TDMA cycles than existing algorithms. The result in this paper supports the credibility of our GNN algorithm for a class of combinatorial optimization problems.

We have demonstrated the single-chip RF front-end GaAs MMIC for the Japanese Personal Handy-phone System. It has a high efficiency HPA, a T/R switch, a LNA and a low-distortion down converter mixer. The IC employs a negative voltage generator for use of single voltage DC power supply. The HPA provides an output power of 21.5 dBm, with an ACPR of 55 dBc and an efficiency of 35%. The LNA has a noise figure of 1.6 dB and a gain of 14 dB with current of 2.3 mA. The newly developed active cascode FET mixer has a high IIP3 of 1 dBm with a high conversion gain of 10 dB and low consumption current of 2.3 mA. The IC is characterized by high performance for RF front-end of PHS handheld terminals. The IC is available in a 7.0 mm6.4 mm1.1 mm plastic package.

Following our former works on regular sampling in wavelet subspaces, the paper provides two algorithms to estimate the truncation error and aliasing error respectively when the theorem is applied to calculate concrete signals. Furthermore the shift sampling case is also discussed. Finally some important examples are calculated to show the algorithm.

We consider a system of coupled two oscillators with external force. At first we introduce the symmetrical property of the system. When the external force is not applied, the two oscillators are synchronized at the opposite phase. We obtain a bifurcation diagram of periodic solutions in the coupled system when the single oscillator has a stable anti-phase solution. We find that the synchronized oscillations eventually become in-phase when the amplitude of the external force is increased.

The change over from IPv4 to IPv6 entails a potential increase in the number of records that the Registry System must maintain. Currently, only a few Network Information Centers (NICs), controlled by Internet Assigned Number Authority (IANA), operate their Registry Systems. As they concentrates data into several Registry System, it is not scalable. This paper focuses on the scalability issue in a Registry System and Mie Advanced Registry System (MARS) is proposed. Through the collaboration of independent Registry Systems, MARS ensures data consistency as well as making it possible to access data managed by other Registry Systems. A prototype system of MARS is implemented, maintained and managed on the WIDE 6bone. Some lessen from the operation of MARS give also described.

The effect of lot size change and test processing logistics on VLSI manufacturing final test process efficiency and cost due to the transition of from conventional 5 or 6 inches to 300 mm (12 inches) in wafer size is evaluated through simulation analysis. Simulated results show that a high test efficiency and a low test cost are maintained regardless of arrival lot size in the range of the number of 300 mm wafers per lot from 1 to 25 and the content of express lots in the range of up to 50% by using WEIGHT+RPM rule and the right final test processing logistics. WEIGHT+RPM rule is the rule that considers the jig and temperature exchanging time, the lot waiting time in queue and also the remaining processing time of the machine in use. The logistics has a small processing and moving lot size equal to the batch size of testing equipment.

A new frame-based packet scheduling discipline designed for variable length packets is discussed. This algorithm extends a weighted round robin scheduling so that it can serve each queue fairly even if the length of packets varies. It can also handle burstiness by one of its important properties which we call "elasticity." In this paper, an overview of the proposed algorithm is described, and then it is systematically analyzed in terms of several important performance parameters: throughput, work complexity and elasticity. The proposed algorithm is evaluated by simulation and compared with the normal weighted round robin with regard to throughput and delay performance, thereby validating fairness of the algorithm with various types of traffic. Focusing on the complexity of the scheduling algorithm, we further propose and evaluate an improved version of the proposed algorithm, which provides the same properties with lower work complexity.

The optimistic consistency scheme has been established with respect to data consistency and availability in distributed systems. The nomadic data consistency model using version vectors to support data versioning for data synchronization and concurrent conflict detection is suitable for an optimistic replication system that supports large-scale wireless networks. This paper describes the architecture and its data consistency model using data versioning and its access domain control targeted for nomadic data sharing systems, such as collaborative works using database and messaging, and the data transfer optimizations of the model. We evaluate our data versioning scheme comparing with a traditional data versioning and the data transfer optimization by estimation and measurement assuming a mobile worker's job. We generate arithmetic formulas for data transfer estimation using the optimizing techniques and apply them to large-scale data sharing configurations in which collaboration groups are dynamically formed and data is exchanged in each group. The data versioning with an access domain increases flexibility in data sharing configurations, such as mobile collaboration systems and client/server type mobile systems. We confirmed that the combination of the general optimizations and the access domain configurations based on our data consistency model is applicable for large-scale mobile data sharing systems.

Network applications such as FTP, WWW, Mirroring etc. are presently operated with little or no knowledge about the characteristics of the underlying network. These applications could operate more efficiently if the characteristics of the network are known and/or are made available to the concerned application. But network characteristics are hard to come by. The IP Performance Metrics working group (IETF-IPPM-WG) is working on developing a set of metrics that will characterize Internet data delivery services (networks). Some tools are being developed for measurements of these metrics. These generally involve active measurements or require modificationsin applications. Both techniques have their drawbacks. In this work, we show a new and more practical approach of estimating network characteristics. This involves gathering and analyzing the network's experience. The experience is in the form of traffic statistics, information distilled from management related activities and ubiquitously available logs (squid access logs, mail logs, ftp logs etc. ) of network applications. An analysis of this experience provides an estimate of the characteristics of the underlying network. To evaluate the concept we have developed and experimented with a system wherein the network characteristics are generated by analyzing the logs and traffic statistics. The network characteristics are made available to network clients and administrators by Network Performance Metric (NPM) servers. These servers are accessed using standard network management protocols. Results of the evaluation are presented and a framework for efficient operation of network operations, using the network characteristics is outlined.

This paper shows the applicability of the integral equation formulation of the measured equation of invariance (IE-MEI) to two-dimensional dielectric scatterers. That is, a relationship between the scattered electric and magnetic fields, which is derived from the new formulation of the IE-MEI, is applicable to lossless dielectric materials as well as perfect electric conductors (PEC). In addition, we show that the IE-MEI does not suffer from internal resonance problems. These two facts are validated by numerical examples for a circular cylinder and a square cylinder illuminated by Transverse Magnetic (TM) plane wave or a TM line source very close to the scatterers. The numerical results calculated by the IE-MEI agree well with the ones by moment methods that employ combined field formulations with exact boundary conditions.