This paper presents an efficient scheme for access bandwidth control for VBR (Variable Bit Rate) traffic between radio mobile terminals and their base stations in a WATM (Wireless ATM) network. After introducing the wireless ATM system model, we describe a new algorithm that enables dynamic slot allocation under TDMA/TDD (Time Division Multiple Access/Time Division Duplex) Media Access Control, making use of UPC (Usage Parameter Control) parameters and traffic characteristics. We show more efficient bandwidth utilization with our proposed algorithm, compared to other conventional algorithms. Moreover, we reveal that our algorithm improves cell transmission delays.

This paper proposes a multipath interference canceller (MPIC) for orthogonal code multiplexed channels in the W-CDMA forward link and evaluates by computer simulation the improvement in BER performance owing to the multipath interference (MPI) suppression effect obtained by the MPIC. The simulation results show that a one-stage MPIC, which removes the MPI from the common pilot channel (PICH), common control channel (CCH), and synchronization channel (SCH), achieves a sufficient MPI suppression effect, and that the required received Eb/N0 of the traffic channel (TCH) at the average BER of 10-3 using the MPIC for the common channels is decreased by approximately 6.5 dB compared to that with a matched filter (MF)-based Rake receiver (the transmit power ratio of each common channel to TCH: ΔPICH/TCH=0 dB, ΔCCH/TCH=5 dB, ΔSCH/TCH=3 dB, without fast transmit power control (TPC) and antenna diversity reception). We also show that by using MPIC, the required transmit Eb/N0 at the average BER of 10-3, when the ratio of the target Eb/I0 of the 9-interfering users to desired user is ΔInt/Des=6 dB with fast TPC, is increased by only approximately 0.6 dB compared to that when ΔInt/Des=0 dB. This implies that the preferential MPI suppression from high-rate TCHs that abates the increase in complexity in a mobile terminal is effective in increasing the link capacity in the forward link.

A noise suppression algorithm with high speech quality based on weighted noise estimation and MMSE STSA is proposed. The proposed algorithm continuously updates the estimated noise by weighted noisy speech in accordance with an estimated SNR. The spectral gain is modified with the estimated SNR so that it can better utilize the improvement in noise estimation. With a better noise estimate, a more correct SNR is obtained resulting in the enhanced speech with low distortion. Subjective evaluation results show that five-grade mean opinion scores of the new algorithm with and without a speech codec are improved by as much as 0.35 and 0.40 respectively, compared with either the original MMSE STSA or the EVRC noise suppression algorithm.

A Multiwavelength Brillouin/Erbium fibre laser which operates in long-wavelength band (L-band) is demonstrated with an approximate comb spacing of 10 GHz. The laser configuration consists of a long EDF to enable the L-band amplification and two 3-dB couplers to take a portion of the generated BEFL signal and re-inject it into the SMF to seed a cascaded BEFL line in the same direction as the first BEFL line. 20 lines including the anti-Stokes are obtained with the maximum Brillouin pump and 980 nm-pump power of 8.9 mW and 92 mW, respectively.

In this paper, we propose a new fair queueing algorithm to improve cell delay variation (CDV) for real-time service categories and to make efficient use of system resources for multimedia traffic in high speed ATM networks. The proposed algorithm is called the delay variation-based fair queueing (DVFQ) algorithm, which is based on per-VC queueing to improve CDV and fairness for each VC of real-time services such as CBR and rt-VBR. In DVFQ algorithm, we define two fairness indexes, which indicate the degree of the fairness of CDV at the rate of each VC, and the degree of impartially sharing the bandwidth between the scheduled cells for each VC. The simulation results for both heavily and lightly loaded conditions show that DVFQ algorithm provides better performances in terms of the CDV, the CDV fairness, and the service fairness than those of FCFS for real-time service.

This paper proposes an innovative Pipeline-based Maximal-sized Matching scheduling approach, called PMM, for input-buffered switches. It dramatically relaxes the limitation of a single time slot for completing a maximal matching into any number of time slots. In the PMM approach, arbitration is operated in a pipelined manner, where K subschedulers are used. Each subscheduler is allowed to take more than one time slot for its matching. Every time slot, one of the subschedulers provides the matching result. We adopt an extended version of Dual Round-Robin Matching (DRRM), called iterative DRRM (iDRRM), as a maximal matching algorithm in a subscheduler. PMM maximizes the efficiency of the adopted arbitration scheme by allowing sufficient time for the number of iterations. We show that PMM preserves 100% throughput under uniform traffic and fairness for best-effort traffic of the non-pipelined adopted algorithm, while ensuring that cells from the same virtual output queue (VOQ) are transmitted in sequence. In addition, we confirm that the delay performance of PMM is not significantly degraded by increasing the pipeline degree, or the number of subschedulers, when the number of outstanding requests for each subscheduler from a VOQ is limited to 1.

In this letter a low-complexity and low-power realization of the 2D discrete-cosine-transform and its inverse (DCT/IDCT) is presented. A VLSI circuit based on the Chen algorithm with the distributed arithmetic approach is described. Furthermore low-power design techniques, based on clock gating and data driven switching activity reduction, are used to decrease the circuit power consumption. To this aim, input signal statistics have been extracted from H.263/MPEG verification models. Finally, circuit performance is compared to known software solutions and dedicated full-custom ones.

Call demand suddenly and greatly increases in the aftermath of a major disaster, because people want to check on their families and friends in the stricken area. Many call attempts in mobile cellular systems are blocked due to the limited radio frequency resources. In this paper, as a solution to this problem, limiting the holding time of calls is investigated and a dynamic holding time limit (DHTL) method, which varies the holding time limit dynamically based on the number of call attempts, is proposed. The effect of limiting the holding time is investigated first using a computer simulation with a constant and heavy traffic load model. This simulation shows that the average holding time of calls is decreased as the holding time limit is reduced. But it also shows limiting the holding time decreases the number of calls blocked and forced call terminations at handover considerably. Next, a simple estimation method for the holding time limit, which reduces the blocking rate to the normal rate for increasing call demand, is described. Finally, results are given of a simulation, which show that the DHTL method keeps good performance for a sudden and great traffic load fluctuation condition.

In this paper, a novel method of clock feedthrough reduction in CMOS autozeroed operational amplifiers with three-phase clock operation is presented. The operational amplifiers in the method are configured by two autozeroed-gain stages. The differential input stage and the second output gain stage are autozeroed individually by a three-phase clock for autozeroing. The three-phase clock is provided so as to finish the compensation period of the input stage earlier than the end of the second stage compensation period. This operation makes it possible to absorb affection of clock feedthrough in the input stage with the second stage. As a result, residual error of offset compensation is much reduced by the voltage gain of the first stage. The effect of the two-stage autozeroing has been confirmed with SPICE simulation and fabricated CMOS circuit. The results of SPICE simulation showed that the two-stage autozeroed operational amplifier has significant advantage as compared to conventional configuration. Affection of clock feedthrough is reduced to about 1/50 in the two-stage configuration. Fabricated CMOS circuit also showed high potential of the two-stage autozeroed operational amplifier for feedthrough reduction. It has been proven experimentally that the two-stage autozeroing is an effective design approach to reduce clock feedthrough error in CMOS autozeroed operational amplifiers.

In this paper, we propose the code orthogonalizing filter (COF) based adaptive array antenna using sample matrix inversion with common correlation matrix (CCM-SMI) of time domain signals for multicarrier DS/CDMA systems. The conventional array antenna system calculates the weight using the correlation matrix of individual subcarrier's signals. On the other hand, our proposed system calculates the weight using the correlation matrix of time domain signals before FFT operation, so it can reduce the calculation time and the complexity of weight calculation than the conventional scheme, to maintain the system performance. Moreover, we consider the code orthogonalizing filter to reduce the demerit of adaptive array antenna system using sample matrix inversion algorithm with common correlation matrix that requires heavy computational complexity while the signal environment frequently changes. Our proposed system obtains more accurate channel response vector using COF than that of the conventional CCM-SMI based on the matched filter, without increasing the matrix size. The performance is evaluated in term of bit error probability. From the analysis and simulation results, it is shown that our proposed scheme achieves better BER performance than that of the conventional system.

In order to clarify the receiver sensitivity of remote keyless entry systems operating at 314 MHz, the radiation characteristics of a cabin antennas must be studied. For this purpose, electromagnetic simulations are very useful but the multiple reflected waves present in the cabin must be accurately estimated. No prior study examined the radiation characteristics of cabin antennas. This paper introduces an accurate simulation method. A MM (Method of Moments) simulator is selected because it can simulate multiple reflected waves. Initial studies are being performed to find the calculation requirements and ensuring convergence of multiple reflected wave structures. Next, calculation requirements for car analyses such as convergence parameters and computer abilities are studied. The calculation time is 11 hours by a personal computer. 1.1 GB of RAM is also needed. Many calculated results such as three-dimensional radiation patterns and induced currents on the car's body are obtained. The radiation pattern varies with antenna position, and polarization changes are shown. In order to ensure that the results are accurate, measurements are made on a one seventh scale model of a car. The good agreement of measured and calculated results verifies the validity of the simulation method. The influence of multiple reflected waves on the radiation patterns is also experimentally studied. The conclusion is that the MM method is shown to be useful in estimating the radiation pattern of cabin antennas. Interesting calculation results are also shown.

Dual-Banyan is a buffered banyan asynchronous transfer mode (ATM) switch encompassing bifurcated queueing as its buffering strategy. This paper describes an efficient analytical model, based on iterative calculations, for performance evaluation of the Dual-Banyan switch under uniform and non-uniform traffic patterns with much less time than the simulation. The efficiency of the given model is verified through a comparison with simulation results. Another benefit of our model is the possibility to adopt it in any non-uniform incoming traffic. At last, we compare performance of Dual-Banyan switch and Input Buffer Banyan, and show that Dual-Banyan switch has significant better performance levels.

A study on improving the performance of the real-coded genetic algorithm for electromagnetic inverse scattering of two-dimensional perfectly conducting cylinders is presented. Three schemes, namely, the penalty function approach, the closed cubic B-splines local shape function approach and the adaptive hybrid algorithm approach are proposed to deal with the problem. These schemes can be used separately or be combined to improve the performance. Numerical examples validate the schemes.

Common-mode (CM) radiation from a cable attached to a conducting enclosure has a typical dipole-type antenna structure, in which an equivalent noise voltage source located at the connector excites the attached cable against the enclosure to produce radiated emissions. Based on this mechanism, a simple method for predicting the CM radiation from the cable/enclosure structure was proposed. The method combines an equivalent dipole approximation with sinusoidal current distribution and CM current measurement at a specified location on the cable. Its validity was examined in comparison with the far-field measurement and finite-difference time-domain (FDTD) modeling. The predicted resonance frequencies and CM radiation levels were validated with engineering accuracy, i.e., within 30 MHz and 6 dB, respectively, from the measured and FDTD-modeled results in the frequencies above 150 MHz.

We propose using a soft decision-directed least-mean-square algorithm in a code-aided equalization scheme for fading channels. Soft-output Viterbi algorithm (SOVA) is modified and applied to strengthen the second-stage equalizer adaptation in the scheme. Simulation results are presented for bit error rate performance in a multipath environment for various normalized fade rates. The proposed equalizer scheme is shown to provide significant bit error rate improvement compared to conventional equalization schemes.

Both tiers are assumed to share the same frequency band. Unlike a single tier cell environment, interference components to be considered in a hierarchical cell environment include the inter-tier interference as well as the intra-cell and the inter-cell interference. The numerical results show that the transmission power ratio between the macro cell and the micro cell affects the forward link capacity. And the results also show that the macro cell capacity increases as the mobile moves toward the edge of the macro cell. Moreover, soft handoff makes it possible to obtain a higher forward link capacity in the handoff region.

A novel self-alignment process using the surface tension of the liquid resin for assembly of electronic or optoelectronic devices in 3-D space has been proposed. The vertical alignment can be controlled by using of metal sphere, reducing the necessary precise process control such as solder volumes and external forces, and allowing large tolerances in liquid volume and misalignment. Lateral alignment could be also achieved by making the liquid resin constrained on the 3-dimensional pads on chip and substrate. This study focused on the principle of self-alignment and final alignment accuracy. In addition, the possibility of self-alignment process was verified by analytic numerical method and scaled-up experiment. An average alignment accuracy of less than 0.25 µm has been obtained. It is thought that this process is effective for assembly simply at low process temperature, low cost and without flux in future assembly techniques.

This paper presents a new method of designing a dither matrix based on simulated annealing. An obtained dither matrix (halftone screen/mask) is appropriate for press printing. Because of several physical reasons, halftoning for press printing is more difficult than halftoning for electronic displays, or ink-jet printers. Even if stochastic dispersed-dot screening (so-called FM-screening) is one of the best solutions for halftoning, that is not appropriate for press printing. On the other hand, classical periodic clustered-dot screening (so-called AM-screening) is more important and is widely used even now. We recognize unfavorable quality of AM-screening, but we can not ignore its productive stability in printing section. The proposed halftone dither matrix has aperiodic clustered-dot pattern, and size of cluster can be controlled by a weighting parameter of a cost function. We will obtain a dither matrix which consists of clustered-dots. Some characteristics of the design algorithm and halftoned images are investigated in detail. As a result, the fact that an obtained dither matrix is superior to AM-screen and comparable to FM-screen in visual quality, and the matrix is comparable to AM-screen and superior to FM-screen in press printability is confirmed.

New methods for digital image watermarking based on the characteristics of vector quantization (VQ) are proposed. In contrast with conventional watermark embedding algorithms to embed only one watermark at a time into the original source, we present one algorithm to embed multiple watermarks for copyright protection. The embedding and extraction processes are efficient for implementing with conventional VQ techniques, and they can be accomplished in parallel to shorten the processing time. After embedding, embedder would output one watermarked reconstruction image and several secret keys associated with the embedded watermarks. These secret keys are then registered to the third party to preserve the ownership of the original source in order to prevent the attackers from inserting counterfeit watermarks. Simulation results show that under no attacks, the embedded watermarks could be perfectly extracted. If there are some intentional attacks in our simulation, all the watermarks could survive to protect the copyrights. Therefore, we are able to claim the robustness, usefulness, and ease of implementation of our algorithm.

The purpose of this study is to show the chaotic features of rhythmic joint movement. Depending on the experimental conditions, one (or both) elbow angle(s) was (were) measured by one (or two) goniometer(s). Pacing was provided for six different frequencies presented in random order. When the frequency of the pace increased, the fractal dimension and first Lyapunov exponent tended to increase. Moreover, the first Lyapunov exponent obtained positive values for all of the observed data. These results indicate that there is chaos in rhythmic joint movement and that the larger the frequency, the more chaotic the joint movement becomes.