This paper presents data coding techniques for a stable single-bit noise-shaping quantizer, which has a cascade structure of a multi-bit ΣΔ modulator and a binary interpolator. The binary interpolator chooses a pre-optimized binary vector for each input sample and successively generates the chosen binary vector as an output bit stream. The binary vectors can have different lengths. The paper also proposes two methods to evaluate and bound output errors of a binary interpolator. A multi-bit ΣΔ modulator is designed to cause no overload for all possible input signals whose amplitudes are bounded to a specified level, and thus the ΣΔ modulator rigorously guarantees the stability condition. In design examples, we have evaluated Signal-to-Noise and Distortion Ratios (SNDRs) and noise spectra and then confirmed that our stable quantizers can sharply shape output noise spectra.

Quality of service (QoS) technology has been implemented and started to be applied to new applications on the next-generation Internet. However, as new applications have many kinds of features and requirements, some additional features should be added to current QoS control technology. For example, they require a definition of a single policy to operate QoS control in the management domain consistently and efficiently. Policy definition for transport layer in a domain and among domains is being discussed at IETF to set a standard process, however detailed policy corresponding to the application or contents information according to the application semantics has not been discussed. Therefore we developed QoS policy control mechanism using metadata which is defined as a structured data according to the application semantics. Though metadata and transport mechanism can be located into quite different positions in the concept of network layers, we made them successfully collaborated by defining meta policy. In this paper, we describe our approach to define a meta policy based on the requirements and information contents from the application as a high level layer concept to be able to classify the network behavior. Our approach enables to multiple QoS control and collaboration among domains. We also report of the activities in IETF and ITU-T.

Embedded-DRAM (eDRAM) power-energy estimation model is proposed for system-on-a-chip (SOC) applications. The main feature is the signal swing based analytic (SSBA) model, which improves the accuracy of the conventional SRAM power-energy models. The power-energy estimation using SSBA model shows 95% accuracy compared with the transistor level power simulation for three fabricated eDRAMs. The SSBA model combined with the high-level simulator provides fast and accurate system level power-energy estimation of eDRAM.

An LCD Driver IC includes more than 300 buffer amplifiers on a single chip. The phase compensation capacitors (on-chip Miller capacitors) for the amplifiers are more than 1000 pF and occupy a large chip area. This paper describes a two-gain-stage amplifier in which an on-chip Miller capacitor is not used for phase compensation in an LCD Driver IC. In the proposed amplifier, phase compensation is achieved only by a newly introduced zero, which is formed by the load capacitance and a phase compensation resistor connected between the output of the amplifier and the capacitive load. Designs of the phase compensation resistor and the amplifier before compensation are discussed, considering a typical load capacitance range. The test chip was fabricated. The newly introduced zero successfully stabilized the amplifier. The chip area for the amplifier was reduced by 30-40%, compared with our previously reported one. The current consumption of the amplifier was only 5 µA. The experimental results of the fabricated test chip support that the proposed amplifier is suitable to an LCD driver IC with a smaller chip area.

This paper describes low-power and low-voltage analog circuit techniques applicable to deep sub-micron LSIs in baseband and RF signal processing. The trends indicate that reductions in the supply voltage are inevitable, that power dissipation will not become sufficiently low, and that performance will improve continuously. Some circuit techniques currently being used to achieve these goals are reviewed. Next, three trial approaches are introduced. The first of these is a 1 V operational video-speed CMOS sample-and-hold IC. The second is a 1 V operational high-frequency CMOS VCO circuit. Finally, a step-down DC-DC converter IC with a 1 V output and a greater than 80% power efficiency is introduced. These approaches prove that the low-power and low-voltage operation of analog circuits can be realized without sacrificing performance.

In this paper, we propose a novel higher order time-frequency distribution (GDH) for a discrete time signal. This distribution is defined over the original discrete time-frequency grids through a delicate discretization of an equivalent expression of a higher order distribution, for a continuous time signal, in [4]. We also present a constructive design method, for the kernel of the GDH, by which the distribution satisfies (i) the alias free condition as well as (ii) the marginal conditions. Numerical examples show that the proposed distributions reasonably suppress the artifacts which are observed severely in the Wigner distribution and its simple higher order generalization.

Most of the QoS-based routing schemes proposed so far focus on improving the performance of individual service classes. In a multi-class network where high priority QoS traffic coexists with best-effort traffic, routing decision for QoS sessions will have an effect on lower ones. A mechanism that allows dynamic sharing of link resources among multiple classes of traffic is needed. In this paper we propose a multi-class routing algorithm based on inter-class sharing resources among multiple class of traffic. Our algorithm is based on the concept of "the virtual residual bandwidth," which is derived from the real residual bandwidth. The virtual residual bandwidth is greater than the residual bandwidth when the load of lower priority traffic is light, and smaller when the load of lower priority traffic is heavy. The idea of our approach is simple since the routing algorithm for individual traffic doesn't change, but the only change is the definition of the link cost. We demonstrate through some extensive simulations the effectiveness of our approach when the best effort distribution is uneven and when its load is heavy. Also better performance is noticed when using topology with large number of alternative paths.

The format conversion operations between a floating-point number and an integer number and a round operation are the important standard floating-point operations. In most cases, these operations are implemented by adding additional hardware to the floating-point adder. The SR (simultaneous rounding) method, one of the techniques used to improve the performance of the floating-point adder, can perform addition and rounding operations at the same stage and is an efficient method with respect to the silicon area and its performance. In this paper, a hardware model to execute CRops (conversion and rounding operations) for the SR floating-point adder is presented and CRops are analyzed on the proposed hardware model. Implementation details are also discussed. The proposed scheme can maintain the advantages of the SR method and can perform each CRop with three pipeline stages.

In this letter we present a new way for computing generalized eigenvalue problems in engineering applications. To transform a generalized eigenvalue problem into an associated problem for solving nonlinear dynamic equations by using optimization techniques, we can determine all eigenvalues and their eigenvectors for general complex matrices. Numerical examples are given to verify the formula of dynamic equations.

For base station antenna array systems with time-division-duplex (TDD) mode, downlink channel responses are equal to uplink channel responses if the duplexing time is small, thus it is often believed that TDD mode simplies downlink beamforming problem as uplink weights can be applied for downlink directly. In this letter, we show that for TDD DS-CDMA systems, even though uplink and downlink channel responses are equal, optimal uplink weights are no longer equal to the optimal downlink ones due to asynchronous property in uplink and synchronous property in downlink, as well as different data rate traffic and QoS requirements. Computer simulations show that for asymmetric traffic, if uplink weights are used for downlink directly, downlink system capacity is less than 50% of that with optimal downlink weights.

This paper introduces an improved multistage parallel interference cancellation (PIC) technique that uses the reverse-link synchronous transmission technique (RLSTT) to improve the estimation of data at the initial stage. Because the subtraction of an interfering signal based on an incorrect bit decision quadruples the interference power for that signal, the relatively high decision bit error rate (BER) may lead to a poor cancellation or even a higher BER at the following stages. The RLSTT is a robust approach which takes into account the fact the tentative decision at the earlier stages is less reliable than the following stages and makes the earlier cancellation more reliable. The analysis demonstrates that a better transmission performance can be achieved by using the RLSTT at the initial stage of PIC.

A voltage-mode universal biquadratic filter using single current-feedback amplifier (CFA), two capacitors and three resistors is presented. The new circuit has four inputs and one output and can realize all the standard filter functions, that is, lowpass, bandpass, highpass, notch and allpass filters, without changing the circuit topology. The use of only one current-feedback amplifier simplifiers the configuration.

In this paper, a new voice personality transformation algorithm which uses the vocal tract characteristics and pitch period as feature parameters is proposed. The vocal tract transfer function is divided into time-invariant and time-varying parts. Conversion rules for the time-varying part are constructed by the classified-linear transformation matrix based on soft-clustering techniques for LPC cepstrum expressed in KL (Karhunen-Loève) coefficients. An excitation signal containing prosodic information is transformed by average pitch ratio. In order to improve the naturalness, transformation on the excitation signal is separately applied to voiced and unvoiced bands to preserve the overall spectral structure. Objective tests show that the distance between the LPC cepstrum of a target speaker and that of the speech synthesized using the proposed method is reduced by about 70% compared with the distance between the target speaker's LPC cepstrum and the source speaker's. Also, subjective listening tests show that 60-70% of listeners identify the transformed speech as the target speaker's.

Hypercomplex coefficient digital filters provide several attractive advantages such as compact realization with reduced system order, inherent parallelism. However, they also possess a drawback in that a multiplier requires a large amount of computations. This paper proposes a computationally efficient implementation of digital filters whose coefficient is a type of hypercomplex number; a bicomplex number. By decomposing a bicomplex multiplier into two parallel complex multipliers, we show that hypercomplex digital filters can be implemented as two parallel complex digital filters. The proposed implementation offers more than a 60% reduction in the count of real multipliers.

A digital calibration technique, which corrects errors due to capacitor mismatch in pipelined ADC and directly measures the error coefficients using the ADC INL plot, is described. The proposed technique can be applied for various types of pipelined ADC architectures. Test results using an implemented 10-bit pipelined ADC show that the ADC achieves a peak signal-to-noise-and-distortion ratio of 56.5 dB, a peak integral non-linearity of 0.3 LSB, and a peak differential non-linearity of 0.3 LSB using the digital calibration.

This paper describes an effective technique for coding QCIF video sequences based on a JPEG2000 codec. In the proposed method, multiple frames are combined into one large picture. The larger picture enables images to be coded more efficiently. Image quality is further improved by combining the frames symmetrically. The video sequence is efficiently coded by adapting the time correlation of the video sequences to spatial correlation. We demonstrated the effectiveness of this method by encoding QCIF video sequences using JPEG2000.

A novel formulation for the Scalar-field approach of Integral Equation formulation of the Measured Equation of Invariance (SIE-MEI) is derived from the scalar reciprocity relation to solve the scalar Helmholtz equation. The basics of this formulation are similar to IE-MEI method for the electromagnetic (EM) problem. The surface integral equation is derived from reciprocity relation and on-surface MEI postulates are used. As a result it generates a sparse linear system with the same number of unknowns as of Boundary Element Method (BEM) and keeps the merits in minimum storage memory requirements and CPU time consumption for computing the final matrix. IE-MEI method has been proposed for two-dimensional (2D) electromagnetic problem, but three-dimensional (3D) problem is very difficult to be extend. This scalar-field approach of IE-MEI method is identical to electromagnetic in 2D, but easily extended to the 3D scalar-field scattering problem contrary to EM problem. The numerical results of sphere and cube are verified with some rigorous or numerical solutions, which give excellent agreement.

A new modified maximum likelihood (ML) algorithm for frame synchronization in discrete multitone VDSL transmission system is presented. Computer simulation results are included to show its improvement in Et/N0 of each tone in the received data. This algorithm estimates the frame boundary at the initial transition edge rather than at the middle peak of a shortened twisted-pair channel response. The timing margin degradation caused by precursor intersymbol interference (ISI) can be reduced significantly, especially at the sub-channel loaded with more bits.

A hybrid data transmission technique for multimedia satellite broadcasting is proposed. The main-channel data and sub-channel data are simultaneously transmitted using QPSK modulation and 2ASK modulation, respectively, but the latter modulation timing is offset by half the main-channel QPSK symbol length in time. The BER performance in a Gaussian channel, the transmission bandwidth, and the transmit power peak factor are theoretically analyzed for various impulse responses of the sub-channel transmit filter. It is found that the use of the sub-channel transmit filter having a sine impulse response minimizes the sub-channel BER while keeping the transmission bandwidth and the transmit power peak factor lower than those of CAPSK transmission.

In CDMA systems, power control strategy is the most important issue since the capacity of the system is only interference-limited. For a better understanding of the effects of Forward Link Power Control Strategy (FLPCS) on the outage probability in fading environments, this paper has presented a theoretical analysis of forward link in a CDMA cellular system by introducing the τ-th power of distance driven control strategy. Based on the power control, the capacity and outage probability of the system are estimated and discussed. In particular, we consider the impact of fading environments and investigate the "hole" phenomenon. Based on our numerical results, the "hole" points are at the upper bounds of where it is possible to ensure minimization of the maximum value of total Interference-to-Signal Ratio (ISR). At those upper bound points, at least, the power control strategy leads to approximately threefold the capacity compared to the case without power control strategy. It can be concluded that the forward link without power control strategy is a very heavy restriction for the capacity of the CDMA system, especially in environments of significant fading.