In this paper we present two traffic control approaches, a circuit emulation traffic control (CETC) and an adaptive priority traffic control (APTC) for supporting voice services in ATM networks. Most voice services can be handled as CBR traffic, this causes a lot of wasted bandwidth. Sending voice through VBR (variable bit rate) may be a better alternative, because it allows the network to allocate voice bandwidth on demand. In CETC, the service discipline guarantees the quality of service (QOS) for voice circuits. Through mathematical analysis, we show that CETC features an adequate performance in delay-jitter. Moreover, it is feasible in implementation. We also present an APTC approach which uses a dynamic buffer allocation scheme to adjust the buffer size based on the real traffic need, as well as employs an adaptive priority queuing technique to handle various delay requirements for VBR voice traffic. It provides an adequate QOS for voice circuits in addition to improving the multiplexing gain. Simulation results show that voice traffic get satisfied delay performance using our approaches. It may fulfill the emerging needs of voice service over ATM networks.

A fractal image coding scheme using classified range regions is proposed. Two classes of range regions, shade and nonshade, are defined here, A shade range region is encoded by the average gray level, while a nonshade range region is encoded by IFS parameters. To obtain classified range regions, the two-stage block merging scheme is proposed. Each range region is produced by merging primitive square blocks. Shade range regions are obtained at the first stage, and from the rest of primitive blocks nonshade range regions are obtained at the second stage. Furthermore, for increasing the variety of region shape, the 8-directional block merging scheme is defined by extension of the 4-directional scheme. Also, two similar schemes for encoding region shapes, each corresponding to the 4-directional block merging scheme and the 8-directional block merging scheme, are proposed. From the results of simulation by using a test image, it was demonstrated that the variety of region shape allows large shade range regions to be extracted efficiently, and these large shade range regions are more effective in reduction of total amount of codebits with less increase of degradation of reconstructed image quality than large nonshade range regions. The 8-directional merging and coding scheme and the 4-directional scheme reveal almost the same coding performance, which is improved than that of the quad-tree partitioning scheme. Also, these two schemes achieve almost the same reconstructed image quality.

A computational cost reduction scheme for a post-distortion type nonlinear distortion compensator of OFDM signals is proposed, and compared with the conventional sub-optimum detection scheme. The proposed scheme utilizes the principle that a complex OFDM signal can be demodulated with not only both I-phase (real part) and Q-phase (imaginary part) components, but also either of them. Usually each phase of an OFDM signal exhibits different signal envelope and they are distorted differently by the nonlinearity of a power amplifier. Consequently, three output sequence patterns can be obtained at the receiver. By comparing these outputs, we can know the erroneous positions of these sequences to some extent. By the aid of this comparison, we need to evaluate only a limited number of replicas for the compensation process of the post-distortion type nonlinear distortion compensator, which results in the computational cost reduction. We have proposed four new compensation schemes based on this idea and derived their performance in terms of the bit error rate and the average number of calculations.

The field profile and effective index of a rib waveguide are calculated using an improved semivectorial beam-propagation method using the imaginary-distance procedure. Convergence behavior of the effective index is compared with that obtained by the conventional Crank-Nicholson scheme and with that derived from a Bierwirth-type formula, demonstrating the effectiveness of the present method. Field discontinuities at the interface between different materials are clearly displayed.

In this paper, we propose a new register transfer level (RT level) testability analysis method. Controllability and observability measures are defined for signal vectors based on the numbers of values they can take. The control part and the datapath part are automatically identified in the given RT level model and distinctive analysis methods are applied. We also describe a DFT point selection method based on our testability measures. In a experiment on a signal processing circuit whose gate count is 7690 including 578 FFs, almost the same fault coverage is achieved with fewer scan FFs than a conventional method based on gate level testability analysis.

In this paper, we propose a test methodology for core-based system LSIs. Our test methodology aims to decrease testing time for core-based system LSIs. In our method, every core is supplied with several sets of test vectors. Every set of test vectors guarantees sufficient fault coverage. Each set of test vectors consists of two parts. One is based on built-in self-test (BIST) and the other is based on external testing. These sets of test vectors are designed to have different ratio of BIST to external testing each other for every core. We can minimize testing time for core-based system LSIs by selecting from the given sets of test vectors for each core. The main contributions of this paper are summarized as follows. (i) BIST is efficiently combined with external testing to relax the limitation of the external primary inputs and outputs. (ii) External testing for one of cores and BISTs for the others are performed in parallel to reduce the total testing time. (iii) The testing time minimization problem for core-based system LSIs is formulated as a combinatorial optimization problem to select the optimal set of test vectors from given sets of test vectors for each core.

Object-oriented analysis methods can be grouped into data-driven and behavior-driven approaches. With data-driven approaches, object models are developed based on a list of objects and their inter-relationships, which describe a static view of the real world. With behavior-oriented approaches, a system usage scenario is analyzed before developing the object models. Although qualitative comparisons of these two types of methods have been made, there was no statistical study has evaluated them based on controlled experiments. This paper proposes the patterned object-oriented method, POOM, which is a behavior-oriented approach, and compares it to OMT, a data-driven approach, using small team experiments. The effectiveness of POOM is shown in terms of productivity and homogeneity.

We have analyzed a very short channel tunneling field effect transistor which uses new heterostructures (CoSi2/Si/CdF2/CaF2) lattice-matched to the Si substrate. In device operation, the drain current from source (CoSi2) to drain (CoSi2) through tunnel barriers (Si) and the channel (CdF2) is controlled by a gate electric field applied to the barrier between the source and the channel through the gate insulator (CaF2). Theoretical analysis shows that this transistor has characteristics similar to those of conventional metal-oxide-semiconductor field effect transistors even with channel lengths as short as 5 nm. In addition, we have estimated the theoretical response time of this transistor and showed the possibility of subpicosecond response.

The influence of loaded capacitance on the resonant frequency of a triplate-type strip resonator is investigated through numerical simulations by means of the finite-difference time-domain (FDTD) method. This type of resonator is one of the basic components of very small high-dielectric stripline filters, named laminated planar filters. Numerical results of resonant frequencies are compared with experimental results and found to be in excellent agreement, which circumstance ensures that the FDTD method can be applied to the characterization of a wide range of laminated planar microwave devices including resonators and filters. It is also found that the resonant frequency is directly related to the square root of its line capacitance when the resonator is regarded equivalently as a series LC circuit.

We discuss optimal rotation estimation from two sets of 3-D points in the presence of anisotropic and inhomogeneous noise. We first present a theoretical accuracy bound and then give a method that attains that bound, which can be viewed as describing the reliability of the solution. We also show that an efficient computational scheme can be obtained by using quaternions and applying renormalization. Using real stereo images for 3-D reconstruction, we demonstrate that our method is superior to the least-squares method and confirm the theoretical predictions of our theory by applying bootstrap procedure.

This paper proposes a novel asynchronous direct sequence/code division multiple access (DS/CDMA) communication system using analog pseudo noise (PN) sequences that have an orthogonal relation for all active users. Analog PN sequences are produced by an adaptive filter called a "code-orthogonalizing filter" (COF). In a base station receiver, the tap coefficients of the COF can be adaptively controlled "to orthogonalize" or "to approach to orthogonalize" various received PN sequences. The elements of the analog PN sequences consist of the tap coefficients of the COF. The analog PN sequence produced is assigned to the transmitter of each user in order. As a result, multiple access interference (MAI) caused by other users can be reduced considerably, and multiple access capacity increased by the proposed system compared with matched filter (MF) reception and COF reception.

M-ary/SS systems are compared with DS/SS systems applied the multicarrier systems and the RAKE receiver in the presence of AWGN, frequency selective Rayleigh fading and partial-band interference. In particular, the BER performance and SSMA capability are evaluated. Consequently, the M-ary/SSMA system using the multicarrier techniques is subject to the M-ary/SSMA system with the RAKE receiver in the presence of partial-band interference. The BER performance of the M-ary/SSMA system is better than that of the DS/SSMA system when the number of users is smaller than 20. And the spectral efficiency of the multicarrier M-ary/SSMA system is best in the four systems when JSR=20 [dB] and BER=10-3.

In this paper, the bit error rate (BER) performance of the Spread Spectrum communication with Constrained Spreading Code system is studied under the synchronous CDMA system. Particularly, BER considering the tracking error is derived by theoretical analysis. The synchronizing spreading sequence is employed to track the signals in the receiver. As the result, the BER performance is degraded by increasing the number of users. However, the BER performance can be improved by canceling the co-channel interference and by suppressing the cross-correlation value between the information spreading sequence and the synchronizing spreading sequence.

In this paper, a novel pass-transistor logic with an efficient level restoration circuit, named Power Saved Pass-transistor Logic (PSPL), is proposed. It is shown how, through the use of regenerative feedback with pMOS switches, we reduce the power consumption and propagation delay compared to conventional pass-transistor logic. To demonstrate the performance of PSPL, a 5454-bit multiplier is designed. For speed and power optimization, the multiplier uses high compression-rate compressors without Booth Encoding, and a 108-bit conditional sum adder with separated carry generation block. The measured multiplication time was 13. 5 ns in a 0. 6 µm single-poly triple-metal 3. 3 V CMOS process. Furthermore, a sequential circuit of a low power 7-bit serial counter is designed and fabricated in a 0. 6 µm single-poly triple-metal 3. 3 V CMOS process. The measured operating speed was 250 MHz.

A new identification algorithm based on output over-sampling scheme is proposed for a IIR model whose input signal can not be available directly. By using only an output signal sampled at higher rate than unknown input, parameters of the IIR model can be identified. It is clarified that the consistency of the obtained parameter estimates is assured under some specified conditions. Further an efficient recursive algorithm for blind parameter estimation is also given for practical applications. Simulation results demonstrate its effectiveness in both system and channel identification.

This paper describes code assignment and the multicode sense scheme for an inter-vehicle CDMA communication network. When considering an inter-vehicle broadcasting CDMA communication network, spreading code assignment and notification problems arise. In such a CDMA network, the use of common codes is a solution. Then an objective function of common code assignment in an IVCN is formulated as a combinatorial optimization problem. In addition, a multicode sense (MCS)/CDMA system is proposed as a simple code assignment scheme. Computer simulations show that the MCS/CDMA system can autonomously perform spatial rearrangement of the common codes using only local information that each vehicle can obtain by sensing the code channels.

In this paper, we present a numerical design method for two-dimensional (2-D) FIR linear-phase (LP) quincunx filter banks (QFB) with equiripple magnitude response and perfect reconstruction (PR). The necessary conditions for the filter length of analysis filters are derived. A dual affine scaling variant (DASV) of Karmarkar's algorithm is employed to minimize the peak ripples of analysis filters and an approximation scheme is introduced to satisfy the PR constraint for the 2-D filter banks (FB). The simulation examples are included to show the effectiveness of this proposed design technique.

This paper presents a variant of the "Third-Order Recursion (TOR)" method for bispectral estimation of transfer-function parameters of a non-minimum-phase all-poles system. The modification is based on the segmentation of system-output data into coupled records, instead of independent records. It consists of considering the available data at the left and the right of each record as not null and taking them as the data corresponding to the preceding and succeeding record respectively. The proposed variant can also be interpreted as a "Constrained Third-Order Mean (CTOM)" method with a new segmentation in overlap records. Simulation results show that this new segmentation procedure gives more precise system parameters than the TOR and CTOM methods, to be obtained. Finally, in order to justify the use of bispectral techniques, the influence of added white and colored Gaussian noise on the parameter estimation is also considered.

Since IIR filters have lower computational complexity than FIR filters, some design methods for IIR filter banks have been presented in the recent literatures. Smith et al. have proposed a class of linear phase IIR filter banks. However this method restricts the order of the numerator to be odd and has some drawbacks. In this paper, we present two design methods for linear phase IIR filter banks. One is based on Lagrange-Multiplier method, and optimal IIR filter banks in least squares sense are obtained. In an other approach, IIR filter banks with the maximum number of zeros are derived analytically.

In mobile communications, power is a very important factor and nonlinear amplification of power amplifiers cannot be avoided due to their high power efficiency. This article presents the performance of π/2-shift BPSK modulation scheme used in DS/SS/CDMA wireless communications over multipath Rayleigh fading channel and compares the performance with the performance of conventional BPSK and offset QPSK CDMA systems. The performance parameters: Out-of-Band power, average Bit Error Rate (BER) and Spectral Efficiency have been evaluated. In order to obtain improved performance on fading channels, a RAKE receiver has been employed. Finally it is shown that π/2-shift BPSK outperforms conventional BPSK and offset QPSK in the presence of nonlinear amplification.