The ATM-ABR service category provides minimum cell rate (MCR) guarantees and robust connections even with insufficient network resources. Recently proposed rate-management algorithms for supporting multimedia applications over ABR mainly aim at minimizing the cell loss and delay. However, jitter is also an important element of QoS for multimedia applications. In this paper, we focus our attention on the arrival point of the critical cell corresponding to the end of data packet and propose a simple cell scheduling scheme for source node to reduce the jitter on application level over the ATM-ABR service class. In our proposed method, critical cells are delayed intentionally and the packet stream at application level becomes smooth. We verify the effectiveness of our proposed algorithm by an analytical model and simulation. From those results, we find that our proposed scheduling algorithm is effective in reducing the application level jitter even when the tagged cell stream is transmitted along the path with multiple nodes.

This paper presents a framework for modeling and mixed-mode simulation of circuits/interconnects and electromagnetic (EM-) radiations. The proposed framework investigates the signal integrity in VLSI chips, packages and wiring boards at the GHz-band level, and verifies the electromagnetic interference (EMI) and the electromagnetic compatibility (EMC) of high-speed systems. In our framework, the frequency characteristics of interconnects and EM-radiations are extracted by the full-wave FDTD simulation. The macromodels of interconnects are synthesized as SPICE subcircuits, and the impulse responses of EM-radiations are stored in the database. Once the macromodels are synthesized, the circuit simulation with the consideration of EM-effects can be performed by using SPICE. The EM-field distributions can be also easily calculated by taking convolutions of pre-simulated EM impulse responses and the SPICE results.

A scalable MOSFET parasitic model has been studied using 0.13 µm standard CMOS process. The model consisted of a core BSIM3v3 transistor model and parasitic resistor, capacitor, inductor, and diode. All parasitic components' values were automatically calculated by transistor geometrical parameters, only gate length (Lg), gate width (Wg), and gate multiple numbers (Mg), and some fixed process parameters such as sheet resistance of each part of diffusion layer. This model was confirmed for 0.25 µm to 0.5 µm gate length, 10 to 40 gate multiples with 5 µm gate finger width (Wf), 0.8 V to 1.5 V gate-source voltage (|Vgs|) with 0.6 V threshold voltage (|Vth|), and 1.0 V to 2.5 V drain-source voltage (|Vds|) from the viewpoint of small signal. The measured s-parameter and simulated one are in fairly good agreement in 200 MHz to 20 GHz frequencies range. This model is very simple, scalable, and convenient for RF circuit designers without difficult parameter setting.

A term rewriting system which effectively preserves recognizability (EPR-TRS) has good mathematical properties. In this paper, a new subclass of TRSs, layered transducing TRSs (LT-TRSs) is defined and its recognizability preserving property is discussed. The class of LT-TRSs contains some EPR-TRSs, e.g., {f(x)f(g(x))} which do not belong to any of the known decidable subclasses of EPR-TRSs. Bottom-up linear tree transducer, which is a well-known computation model in the tree language theory, is a special case of LT-TRS. We present a sufficient condition for an LT-TRS to be an EPR-TRS. Also reachability and joinability are shown to be decidable for LT-TRSs.

Mobility management is a core issue in IP/LEO satellite network related research. The LEO system consists of wide network of moving satellites providing connectivity to any place on the earth. It implies that the system must support numerous wireless connections under high-mobility conditions. Existing mobility management protocols like Mobile IP suppose that two types of identities, indicating a unique name and position in the network, are dynamically bound in each handover. However, in the IP/LEO system, handovers are mainly caused by fast moving satellites, not moving nodes. As a result, quite a few binding update requests are generated during a short period by the moving satellites; this makes mobility management difficult. In this paper, we propose a new mobility management method that separates binding updates from handovers by using geographical location of the nodes. We evaluate the proposed method and show its effectiveness.

Based on a modified step-by-step decoding procedure, a high-speed pipelined Reed-Solomon decoder is presented. The decoder requires only the delay time of three 2-input XOR gates for decoding each coded symbol. The decoder can be operated in a bit rate of Gbits/sec order and thus suitable for the very high speed data transmission systems.

A new source model for MoM analysis by using sinusoidal reaction matching technique is proposed for linear antenna analysis. This source model assumes a constant feeding gap and uniform electric field distribution inside the gap. The analysis results are compared with the results of the conventional models and measurement. It is found that the new model can incorporate the effect of the length of driving gap and is more accurate and more stable than that from the conventional source models. The proposed source model is simple and easy to use. This source model, together with the full kernel formulation, makes it possible to analyze the linear dipole antennas with no limitation of ratio of segment length to radius.

We propose herein a motion detection artificial vision model which uses analog electronic circuits. The proposed model is comprised of four layers. The first layer is a differentiation circuit of the large CR coefficient, and the second layer is a differentiation circuit of the small CR coefficient. Thus, the speed of the movement object is detected. The third layer is a difference circuit for detecting the movement direction, and the fourth layer is a multiple circuit for detecting pure motion output. When the object moves from left to right the model outputs a positive signal, and when the object moves from right to left the model outputs a negative signal. We first designed a one-dimensional model, which we later enhanced to obtain a two-dimensional model. The model was shown to be capable of detecting a movement object in the image. Using analog electronic circuits, the number of connections decrease and real-time processing becomes feasible. In addition, the proposed model offers excellent fault tolerance. Moreover, the proposed model can be used to detect two or more objects, which is advantageous for detection in an environment in which several objects are moving in multiple directions simultaneously. Thus, the proposed model allows practical, cheap movement sensors to be realized for applications such as the measurement of road traffic volume or counting the number of pedestrians in an area. From a technological viewpoint, the proposed model facilitates clarification of the mechanism of the biomedical vision system, which should enable design and simulation by an analog electric circuit for detecting the movement and speed of objects.

In the past, enhancement techniques for the end-to-end quality of a networked application were studied by looking at each individual layer. Examples of such techniques include the error resilience/concealment methods in the application layer, the FEC/ARQ in the transport layer, and the Quality of Service (QoS) techniques in the network layers. However, an integrated approach that would look across all related layers had yet to be investigated. This paper proposes an approach that combines priority-aware video packetization, adaptively used layered FEC, and QoS controlled networks such as IntServ and DiffServ in order to provide an efficient end-to-end quality in layered streaming video. The combination is more efficient in terms of a simple network price mechanism, that is, in getting the best end-to-end quality under a given total cost constraint. Our proposed approach in DiffServ with video packet (VP) data-splitting and layered FEC guarantees minimal service quality in a scalable and cost effective manner without introducing resource reservation. For video, we also propose performance metrics such as corrupted/frozen frame ratio (CFR, FFR). These provide objective metrics like PSNR as well as a measurement for subjective perceptions. Our approach, which combines related layers such as video coding, transport, and network, has yielded results that have proven to be more cost-effective and practical than the supporting network QoS.

A four-pole quasi-elliptic function bandpass filter is designed and fabricated using a miniaturized microstrip square Stepped Impedance Resonator (SIR). The Nonuniform Finite Difference Time Domain (NUFDTD) method is used to design the resonator and to calculate the coupling coefficients of three basic structures. Theoretical and experimental results are presented. This filter is not only compact size but also has a wide upper stop band.

This paper introduces a way to realize high-pass, band-stop and all-pass transfer functions using two-integrator loop structure consisting of loss-less and lossy integrators. The basic circuit configuration is constructed with five Operational Transconductance Amplifiers (OTAs) and two grounded capacitors. It is shown that the circuit can realize their circuit transfer functions by choosing the input terminals, and that the circuit parameters can also be independently set by the transconductance gains with the proportional block. Although the basic circuit configuration has been known, it seems that the feature for realizing the high-pass, the band-stop and the all-pass transfer functions makes the structure more attractive and useful. An example is given together with simulated results by PSPICE.

In the FDTD simulation of microwave circuits, a device in very small size compared with the wavelength is often handled as a lumped element, but it may still occupy more than one cell instead of a wire structure without volume routinely employed in classical extended FDTD algorithms. In this paper, two modified extended FDTD algorithms incorporating a lumped element occupying more than one cell are developed directly from the integral form of Maxwell's equations based on the assumption whether displacement current exists inside the region where a device is present. If the displacement current exists, the modified extended FDTD algorithm can be represented as a Norton equivalent current-source circuit, or otherwise as a Thevenin equivalent voltage-source circuit. These algorithms are applied in the microwave line loaded by a lumped resistor and an active antenna to illustrated the efficiency and difference of the two algorithms.

This paper presents a 0.5Vdd-step pumping method for Dickson-type charge-pump circuits that achieve high overall efficiency, including regulator circuitry, even at large output currents, and these circuits are targeted at mobile equipment applications. We have designed positive and negative charge-pump circuits which use a 0.5Vdd-step pumping method, are implemented with advanced control functions, and are fabricated with our custom CMOS process. Measured results showed that efficiency of a 2.5-stage positive charge-pump circuit before regulation is more than 93% (power supply Vdd=5 V, output voltage Vout=16.9 V 3.5Vdd, output current Iout=4 mA), and that of a 1.5-stage negative charge-pump circuit is 93% (power supply Vdd=5 V, output voltage Vout=-7.2 V -1.5Vdd, output current Iout=4 mA).

A dual-polarized multimode CDMA based local multipoint distribution system (LMDS) is presented. The twisted sector concept and narrowed sector cell are proposed to improve the system performance. Inter-cell interference is analyzed and discussed for the downstream direction based on hexagonal cell architecture. The bit error rate (BER) performance of a multimode CDMA scheme is investigated in terms of the worst case for high order modulation. The simulation results show that the proposed cell structure obtains better power efficiency and makes the multimode CDMA scheme feasible in LMDS deployment.

A three inputs and single output voltage-mode universal biquadratic filter using only two operational transconductance amplifiers (OTAs) and two capacitors is presented. The new circuits offer several advantages, such as employing the minimum number of active and passive components (two OTAs and two capacitors), the versatility to synthesize highpass, bandpass, lowpass, notch and allpass responses without component matching conditions, high input impedance for bandpass and lowpass filter realizations and good sensitivities performance.

This paper describes a simple, inexpensive technique for intentionally broadening and flattening the spectrum of a DC-DC converter (switching regulator) to reduce Electro-Magnetic Interference (EMI). This noise spectrum broadening technique involves intentionally introducing pseudo-random dithering of control clock timing, which can be achieved by adding simple digital circuitry. This technique can significantly reduce noise power spectrum peaks at the DC-DC converter output. For our test case circuit, measurements showed that noise power was reduced by 5.7 dBm at the main peak, by 15.6 dBm at the second peak and by 12.8 dBm at the third peak. This simple, inexpensive technique can be applied to most conventional switching regulators by adding simple digital circuitry, and without any modification of the design of other parts.

In 1999, Araki et al. proposed a convertible limited verifier signature scheme. In this letter, we propose a universal forgery attack on their scheme. We show that any one can forge a valid signature of a user UA on an arbitrary message.

As multimedia and high-speed traffic become more popular on the Internet, the various traffic requiring different qualities of service (QoS) must co-exist. In addition, classified services based on Diff-Serv (Differentiated Service), MPLS (Multi-Protocol Label Switching), etc., have come into wide use. Today's Internet environment requires routers to perform control mechanisms in order to guarantee various QoSs. In this paper, we propose a smart buffer management scheme for the Internet router that uses hierarchical priority control with port class and flow level. Furthermore, since the proposed scheme must operate at very high speed, we first propose several design policy for high speed operation and the hardware implementation is performed in VHDL code. Implementation results show that the proposed scheme can scale with high-speed link, achieving the maximum rate of 4.0 Gbps by using the 3.5 µm CMOS technology.

Class-based delay differentiation model has been recently proposed as a part of relative differentiated services frameworks, and it is shown that the model can provide delay differentiation without admission control and end-to-end resource reservation. In this paper, however, we observe that there can be inconsistent delay differentiation caused by different size of packets. We propose packet size-based delay differentiation model and show that packet size-based queueing is effective to achieve equal delay within a class and provide consistent delay differentiation between classes through simulations. Simulation results also show that the proposed model improves jitter characteristics of CBR flows.

In fractal image coding, for each range block, the best matching domain block is identified, and information from the best matching domains and range blocks are transmitted to the decoder for image reconstruction. In this paper, the similarity between range blocks and domain blocks is evaluated according to their centers of gravity. The number of searched domain blocks are reduced by limiting the candidates for the best matching domain blocks to those domain blocks whose similarity to the range block are high. Using simulation experiments, the number of candidates for the best matching domain blocks were reduced to about 10-23% of the current method. Thus, our proposed method had significantly reduced the number of searched domain blocks below the current method and at the same time it turns out that degradation of the reconstructed image was seldom observed.