This paper proposes "Multipath Control and Proactive Control" to realize a robust QoS control system for mobile multimedia communication in an IP-based cellular network. In this network, all kinds of traffic will share the same backbone network. This requires a QoS system that differentiates services according to the required quality. Though DiffServ is thought to be a promising technique for achieving QoS, an effective path control scheme and a technique that is suitable enough for rapid traffic changes are not yet available. Our solution is multipath control using linear optimization combined with proactive control using traffic anomaly detection. Simulation results show that multipath control and proactive control improve system performance in terms of throughput and packet loss when rapid traffic change takes place.

For multiple-channel active noise control (ANC) systems, distributed systems consisting of more than one controller are useful. In this paper, we propose a performance improvement algorithm for the distributed multiple-channel ANC system based on the simultaneous equations method. In the proposed algorithm, no estimation of error paths is required. This algorithm can provide good performance in canceling primary noises with auto-/cross-correlations and achieve stable noise reduction under a change of the error paths.

In this letter, we study a hybrid Multimedia-on-Demand (MoD) system which provides broadcast, batch and interactive services. An analytical model for such an MoD system is provided. Numerical results show that with proper design, the system can provide better performance than those systems which only provide any subset of two services.

In this paper, we propose a circuit configuration for the low-frequency second-order active RC BPF (band pass filter) which has stable high Q. This proposed circuit is a high Q low-frequency one with a small capacitance, which is realized by applying an output capacitance multiplier to the circuit. Then a detailed circuit analysis is performed for the proposed circuit. From the simulation results of fo and Q for various combinations of circuit element values, we can confirm that the circuit realization of a center frequency of several Hz is possible by employing chip condensers of dozens of nF. The bread-board circuit of this configuration is confirmed to have small temperature dependences of fo and Q by the experiment. It is also clarified from detailed noise analysis and noise measurement that the circuit noise is sufficiently maintained at a low level.

A feedforward-based active shielding technique for digital noise suppression is more preferred for its capability of reducing the noise on the entire area inside the guard ring. In order to compensate for the variation of substrate parameters, an automatic control scheme to tune the gain of the active shield circuit is proposed. Simulation results show the effectiveness of the proposed system in reducing the digital noise regardless of circuit layout. Simulation results also show that noise suppression improvement from passive guard ring to active shield with tuning is 20 dB or one tenth while that from active shield without tuning to active shield with tuning is 12 dB.

Hypersequential programming is a new method of concurrent-program development in which the original concurrent program is first serialized, then tested and debugged as a set of sequential programs (scenarios), and finally restored into the target concurrent program by parallelization. Both high productivity and reliability are achieved by hypersequential programming because testing and debugging are done for the serialized versions and the correctness of the serialized programs is preserved during the subsequent parallelization. This paper proposes scenario-based hypersequential programming for reactive multitasking systems that have not only concurrency and nondeterminacy, but also interruption and priority. Petri nets with priority are used to model reactive systems featuring interruption and priority-based scheduling. How reactive systems are made highly reliable by this approach is explained and the effectiveness of the approach is demonstrated through the example of a telephone terminal control program.

Recently, various types of traffic have increased on the Internet with the development of broadband networks. However, it is difficult to guarantee QoS for each traffic type in current network environments. Moreover, it has been reported that bandwidth can be allocated to flows unfairly, and this can be an important issue for QoS guarantees. Therefore, we have proposed a flow-based queue management scheme, called Dual Metrics Fair Queueing (DMFQ), to improve the fairness and QoS per flow. DMFQ discards arrival packets by considering not only the arrival rate per flow but also the flow succession time. In addition, we have confirmed the effectiveness of DMFQ through several computer simulations. In this paper, we implement DMFQ with hardware for high-speed operation. Concretely, we propose the design policies and show the hardware design results.

Active Queue Management (AQM) can maintain smaller queuing delay and higher throughput by purposefully dropping packets at the intermediate nodes. Most of the existing AQM schemes follow the probability dropping mechanism originated from Random Early Detection (RED). In this paper, we develop a novel packet dropping mechanism for AQM through designing a two-category classifier based on the Fisher Linear Discriminate approach. The simulation results show that the new scheme outperforms other well-known AQM schemes, such as RED, AdaptiveRED, AVQ, PI, REM etc., in the integrated performance. Additionally, our mechanism is simple since it requires few CPU cycles, which makes it suitable for the high-speed routers.

Authenticated Key Establishment (AKE) protocols enable two entities, say a client (or a user) and a server, to share common session keys in an authentic way. In this paper, we review the previous AKE protocols, all of which turn out to be insecure, under the following realistic assumptions: (1) High-entropy secrets that should be stored on devices may leak out due to accidents such as bugs or mis-configureations of the system; (2) The size of human-memorable secret, i.e. password, is short enough to memorize, but large enough to avoid on-line exhaustive search; (3) TRM (Tamper-Resistant Modules) used to store secrets are not perfectly free from bugs and mis-configurations; (4) A client remembers only one password, even if he/she communicates with several different servers. Then, we propose a simple leakage-resilient AKE protocol (cf.[41]) which is described as follows: the client keeps one password in mind and stores one secret value on devices, both of which are used to establish an authenticated session key with the server. The advantages of leakage-resilient AKEs to the previous AKEs are that the former is secure against active adversaries under the above-mentioned assumptions and has immunity to the leakage of stored secrets from a client and a server (or servers), respectively. In addition, the advantage of the proposed protocol to is the reduction of memory size of the client's secrets. And we extend our protocol to be possible for updating secret values registered in server(s) or password remembered by a client. Some applications and the formal security proof in the standard model of our protocol are also provided.

A design optimization of active shield circuit using noise averaging method is proposed. The relation between the averaged noise and the design parameters of the active shield circuit such as circuit gain and on-chip layout is examined. A simple design guideline is also provided. Simulation results show that the active shield circuit designed by the proposed optimization method gives a better noise suppression performance of about 28% than the conventional one.

In this paper, we describe an accelerative current-programming method for active matrix OLED (AM-OLED) display. This new method uses common source configuration, "Acceleration Control" line and some mechanisms to prevent the programming current from flowing through OLED device. It would solve the basic problem of the current-programming pixel circuit: a long programming period, especially at the dark gray-level. The proposed method accelerates the current programming process at any gray levels, and it would be the solution for the problem.

An active shield circuit which effectively reduces the substrate noise on the entire area inside the guard ring regardless of the noise source position is proposed. Simulation result shows that the proposed circuit can reduce the noise level to -85 dB while a conventional guard ring gives -52 dB.

We develop a method of dimensioning and managing the bandwidth of a link on which TCP flows from access links are aggregated. To do this, we extend the application of the processor-sharing queue model to TCP performance evaluation by using flow statistics. To handle various factors that affect actual TCP behavior, such as round-trip time, window-size, and restrictions other than access-link bandwidth, we extend the model by replacing the access-link bandwidth with the actual file-transfer speed of a flow when the aggregation link is not congested. We only use the number of active flows and the link utilization to estimate the file-transfer speed. Unlike previous studies, the extended model based on the actual transfer speed does not require any assumptions/predeterminations about file-size, packet-size, and round-trip times, etc. Using the extended model, we predict the TCP performance when the link utilization increases. We also show a method of dimensioning the bandwidth needed to maintain TCP performance. We show the effectiveness of our method through simulation analysis.

We consider delivering interactive dramas. A viewer interacts with a contents provider by answering multiple-choice questions and the answers to these questions influence the plot of delivered story. All possible plots can be represented by a directed graph such that every plot corresponds to some path of the graph. A delivery should be controlled according to the directed graph such that each viewer's history of answered choices forms a path of the graph. On the other hand, because some character of a viewer is known to a contents provider from his history of choices, a viewer tries to prevent even a contents provider from linking choices made by him. In this paper, we introduce unlinkable delivery for an interactive drama and propose such a delivery system for interactive dramas that viewer's choices are unlinkable and delivery is controlled according to the directed graph.

Leakage power is predicted to become dominant in the total operation power as the transistor technology gets advanced. Even in the current technology, dramatic increase of leakage power at elevated temperature is a big problem. Burn-in testing, which is typically performed at 125, is facing at difficulties such as throughput degradation or thermal runaway due to increase of leakage power. Reducing leakage power at operation time is essential to solve these problems. We propose a novel approach to make use of an enable signal of a gated-clock technique for reducing active leakage power. A sleep transistor is provided between combinational logic circuits and the ground, and is controlled by the enable signal. When state transitions do not occur in Finite-State-Machines (FSM's), the enable signal becomes low and the state flip-flops keep the data. At the same time, the sleep transistor is turned off so that combinational logic gates are electrically disconnected from the ground to reduce leakage. Simulation results have shown that the proposed scheme reduces active leakage power by 30-60% in 0.18 µm technology. The total power was reduced by 20% at the maximum at 125. It was also found that performance degradation was tolerable for burn-in testing.

Since the TCP is the transport protocol for most Internet applications, evaluation of TCP throughput is important. In this paper, we establish a framework of evaluating TCP throughput by simple measurement. TCP throughput is generally measured by sending TCP traffic and monitoring its arrival or using data from captured packets, neither of which suits our proposal because of heavy loads and lack of scalability. While there has been much research into the analytical modeling of TCP behavior, this has not been concerned with the relationship between modeling and measurement. We thus propose a lightweight method for the evaluation of TCP throughput by associating measurement with TCP modeling. Our proposal is free from the defects of conventional methods, since measurement is performed to obtain the input parameters required to calculate TCP throughput. Numerical examples show the proposed framework's effectiveness.

Loss compensation in a RF CMOS active inductor with using a capacitor is proposed. This simple compensation technique yields a negative conductance characteristic that can compensate for the constant internal loss of active devices. Simulation results show that the inductor obtains a maximum Q-value of 1.2E8, an inductance value in the range of 50 nH to 450 nH, and a 1.4E-6 Ω of minimum total equivalent loss in the range of 0.6 GHz to 1.3 GHz.

In IP-based mobile networks, a few of mobility agents (e.g., home agent, foreign agent, etc.) are used for mobility management. Recently, Hierarchical Mobile IPv6 (HMIPv6) was proposed to reduce signaling overhead and handoff latency occurred in Mobile IPv6. In HMIPv6, a new mobility agent, called mobility anchor point (MAP), is deployed in order to handle binding update procedures locally. However, the MAP can be a single point of performance bottleneck when there are a lot of mobile node (MNs) performing frequent local movements. This is because the MAP takes binding update procedures as well as data packet tunneling. Therefore, it is required to control the number of MNs serviced by a single MAP. In this paper, we propose a load control scheme at the MAP utilizing an admission control algorithm. We name the proposed load control scheme proactive load control scheme to distinct from the existing load control schemes in cellular networks. In terms of admission control, we use the cutoff priority scheme. We develop Markov chain models for the proactive load control scheme and evaluate the ongoing MN dropping and the new MN blocking probabilities. As a result, the proactive load control scheme can reduce the ongoing MN dropping probability while keeping the new MN blocking probability to a reasonable level.

In this paper we present a new type of CMOS Time-of-Flight (TOF) range image sensor based on CMOS Active Pixel Sensor (APS) techniques. The TOF sensor features high-speed and efficient photo-charge transfer that is essential in range imaging. The rapid and efficient charge transfer is made possible by the use of a high-gain inverting amplifier and capacitors connected alternatively to the feedback path. This leads to the cost-effective implementation of the system. The analysis of simulation results suggests that the proposed technique can achieve a sufficient range resolution of millimeters to centimeters depending on the maximum measured range, if the noise is dominated by photon shot noise.

In this paper, we propose a fast fractal image coding based on LMSE (least mean square error) analysis and subblock feature. The proposed method focuses on efficient search of contrast scaling, position of its matched domain block, and isometric transform for a range block. The contrast scaling and the domain block position are searched using a cost function that comes from the LMSE analysis of the range block and its fractal-approximated block. The isometric transform is searched using 2 2 blocks formed with the averages of subblocks of range block and domain block. Experimental results show that the encoding time of a conventional fractal image coding with our search method is 25.6-39.7 times faster than that with full search method at the same bit rate while giving PSNR decrement of 0.2-0.7 dB with negligible deterioration in subjective quality. It is also shown that the encoding time of a conventional fractal image coding with our search method is 3.4-4.2 times faster than Jacquin's fractal image coding and is superior by maximum 0.8 dB in PSNR. It also yields reconstructed images of better quality.