This paper presents a new and robust technique for a coarse frequency offset estimation in OFDM system. As an evaluation of the proposed algorithm, we apply it to Eureka 147 DAB system. The proposed coarse frequency offset estimation algorithm is based on the differential detection technique between adjacent subcarriers to eliminate the phase shift effects of symbol timing offset and fractional frequency offset. Coarse frequency offset is determined from the correlation outputs between a received intercarrier differential phase reference symbol and several locally generated but frequency shifted intercarrier differential phase reference symbols. The performance of our estimation algorithm is evaluated by means of computer simulation and compared with that of previous proposed algorithms for DAB transmission modes I, II, III and IV. Simulation results show that the proposed algorithm generates extremely accurate estimates with a low complexity irrespective of the symbol timing offset.

In this paper, we report on design and fabrication of the pipelined digital correlator (PDC) for the opto-electronic discrete correlation processor (OEDCP). The OEDCP consists of optical fan-in and fan-out interconnection systems and several number of PDC's with optical I/O ports. The OEDCP achieves high processing performance with sophisticated combination of optics and electronics. We design and fabricate a prototype of the PDC which is the processing engine of the OEDCP. For the prototype, the pixel number of the input and the output images is 88 and that of the kernel is 33. The designed chip is composed of approximately 10,000 transistors. Operation of the fabricated chip was verified using test vectors.

FDMA/TDMA non-geostationary earth orbit satellite systems (Non-GEOS) generally require a pre-planned pool of radio resource, i.e., frequency and time slot plan (FTSP), for each gateway earth station (GES) prior to the real-time channel assignment by the multiple GES's sharing the resources harmoniously. The time-variant nature of those systems implies that a dynamic FTSP planning method is crucial to the operation to cope with the time-variant traffic demand and the inter-beam interference condition. This paper proposes and compares three algorithms (Serial-numbering, DP-based, and Greedy algorithms) mixed with two strategies (concentrated- and spread-types) for the resource allocation. The numerical evaluation demonstrates that Greedy algorithm with the spread-type strategy is very effective and promising with feasible calculation time for the FTSP generation.

We propose the analytical calculation method of average packet success probability of CDMA Slotted ALOHA systems, which derives accurate probability, and that is applicable to the system with any spreading codes and any amplitude distributions. In the method, we consider the bit-to-bit dependence of amplitude of signals, used spreading sequences, relative timing delays, and relative carrier phases. This bit-to-bit dependence is the case that the parameters above mentioned are constant for a slot time. By using the method to obtain the average packet success probability, we derive useful throughput performance of CDMA Slotted ALOHA systems on fading channel, and show that the normalized throughput becomes worse in the case of larger spreading factor.

Generally, a siren of ambulance is used to let drivers know that an ambulance is approaching. Although the siren system is effective to alert the drivers and pedestrians, the sound of siren is noisy in a cabin of ambulance. In this paper, an active noise control (ANC) system to control the sound of siren using headset is proposed. The proposed ANC system selectively controls only the sound of siren, and other sound such as speech is not affected at all. The achieved attenuation level by the proposed ANC system is more than 20 dB.

The paper proposes a transmitter diversity scheme with a desired signal selection for the mobile communication systems in which the severe cochannel interference (CCI) is assumed to occur at the base station. The feature of the proposed scheme is that the criterion of the downlink branch selection is based on the desired signal power estimated by the correlation between the received signal and the unique word at the matched filter. Moreover, the unique word length control method according to the instantaneous SIR is applied to the proposed scheme, taking account of the uplink transmission efficiency. Computer simulation results show that the proposed scheme provides the better performance than the conventional transmitter diversity in the severe CCI environments, and that the unique word length control method applied to the proposed scheme decreases the unique word length without the degradation of the transmission quality, comparing with the fixed unique word length method.

In this paper, we investigate the performance of Fast Reservation Protocols (FRP) for burst-level bandwidth allocation in ATM networks. FRP schemes can be classified into delayed transmission (DT) and immediate transmission (IT) methods according to reservation procedure. Moreover, according to the responsibility for negative acknowledgment (NAK) cell generations when burst blocking occurs, FRP schemes can be further classified into blocking node NAK (BNAK) and destination node NAK (DNAK) schemes. We analize the FRP schemes with different reservation and NAK methods for single node and multihop network models, respectively. We then discuss the dependence of performance for each FRP scheme on propagation delay, peak rate, and the number of hops.

It is well known that based on the structure of a transversal filter, the RLS equaliser provides the fastest convergence in stationary environments. This paper addresses an adaptive transversal equaliser which has the potential to provide more faster convergence than the RLS equaliser. A comparison is made with respect to computational complexity required for each update of equaliser coefficients, and computer simulations are demonstrated to show the superiority of the proposed equaliser.

The transmission S-parameter, S21, between dipole elements on a rectangular finite ground plane is calculated by the MoM with planar-segments in the horizontally and vertically polarized configurations. Supposed a 1/10 scaling, the frequency range is selected 0.15-0.8 GHz. The size of the finite ground plane is 40 cm 100 cm. The dipole-element length is 18.8 cm (half-wavelength at 0.8 GHz). The distance between dipole elements is 30 cm. The results are compared to the calculated results with the conventional MoM-GTD hybrid method and also the measured results with a TRL-calibrated network analyzer. It makes clear that the MoM-GTD hybrid method is not applicable to a small ground plane in the vertically polarized configuration. The results calculated by the MoM with planar-segments agree well to the measured results both in the horizontal and vertical polarizations. The results show that the size of the finite ground plane for the vertical polarization should be much larger than for the horizontal polarization.

This paper describes the results of a series of laboratory experiments for performance evaluations of our proposed Maximum Likelihood Sequence Estimation (MLSE) based interference canceller, the Interference Canceling Equalizer (ICE), which can cancel both co-channel interference (CCI) and inter-symbol interference (ISI). To verify the feasibility of ICE for the Japanese cellular communications system, a standard of which has been released under the name of Personal Digital Cellular (PDC) system, a prototype system was constructed using 27 TI TMS320C40 Digital Signal Processor (DSP) chips. The ICE prototype works in real-time on the PDC air interface, major specifications of which are π/4 QDPSK 21 k symbols/s 3-channel time-division multiple-access (TDMA). Two-branch diversity reception is used to enhance the signal detection performance of ICE. In the experiments, BER performances were evaluated using the prototype system. Under a single-path Rayleigh fading and a single CCI condition, the ICE receiver attains the BER of less than 310-2 with the negative values of the average CIR: for fD = 5 Hz and 40 Hz, the average CIR more than -20 dB and -10 dB, respectively. Under a double-path Rayleigh fading and a single CCI condition, the ICE receiver attains the BER of less than 1.510-2 with the negative values of the average CIR: for fD = 5 Hz and 40 Hz, the average CIR more than -20 dB and -10 dB, respectively. The laboratory test results suggest that the ICE receiver has potential for system capacity enhancement.

We evaluate the BER performance of the OFDM system with the one-tap equalizer bank under the two-ray multipath channel with the frequency offset by the simple Gaussian analysis method and by a proposed modified Gaussian analysis method. The proposed analysis method considers two adjacent inter-channel interferences, separately, and models the other inter-channel interferences as a Gaussian noise. It is shown that the proposed analysis method affords much closer results to the simulations than those by the simple Gaussian analysis method, when the frequency offset exists.

This paper presents an error resilient H.263 video compression scheme over noisy channels. The start codes in the H.263 bit stream syntax, which inherently provide the resynchronization functionality for error handling, may cause significant error damage if they are incorrectly decoded. Therefore, we develop a video segment regulation algorithm at the decoder to efficiently identify and correct erroneous start codes and block addresses. In addition, the precise error tracking technique is used to further reduce the error propagation effects. After performing the video segment regulation, the decoder can report the exact addresses of detected corrupt blocks back to the encoder via a feedback channel. With these negative acknowledgments, the encoder can precisely calculate and trace the propagated errors by examining the backward motion dependency for each pixel in the current encoding frame. With this precise tracking strategy, the error propagation effects can be terminated completely by INTRA refreshing the affected blocks. Simulation results show that the proposed scheme yields significant video quality improvements over the motion compensated concealment by gains of 4.1 to 6.2 dB PSNRs at bit rate around 35 kbps in error-prone DECT environments. In particular, this scheme complies with the H.263 standard and has the advantages of low memory requirement and low computation complexity that are suitable for practical real-time implementation.

It is one of the difficulties in enterprise modeling that we must deal with many fragmented pieces of knowledge provided by various domain-experts, which are usually based on mutually different viewpoints of them. This paper presents a formal approach to integrate those pieces into enterprise-wide model units using Rough Set Theory (RST). We focus on business processes in order to recognize and identify the constituents or units of enterprise models, which would compose the model expressing the various aspects of the enterprise. We defined five model unit types of "resource," "organization," "task," "function," and "behavior. " The first three types represent the static aspect of the enterprise, whereas the last two types represent the dynamic aspect of it. Those units are initially elicited from each domain-expert as his/her own individual model units, then they are integrated into enterprise-wide units using RST. Our approach is methodology-free, and any methodologies can include it in their early stage to identify what composes the enterprise.

It is always difficult to monitor stringent cell loss ratio (CLR), e.g. 10-9, in asynchronous transfer mode (ATM) networks, because its measurement period is too long for real-time measurement. In this paper, we propose new performance monitoring mechanisms for stringent CLR. We consider virtual ATM switches whose resources are much smaller than the real system and thus much higher CLRs will be obtained within a relatively short measurement period. By applying some regression methods in the CLRs obtained from the virtual system, we can estimate the actual CLR of the real system quite accurately and our performance monitoring mechanisms will be operated based on the estimation. Through the numerical examples, our mechanisms are not only more accurate than the traditional methods, but also have shorter measurement periods compared with direct measurement.

This paper proposes a new adaptation-mode control (AMC) for a robust adaptive microphone array with an adaptive blocking matrix (RAMA-ABM). The proposed AMC is based on cross correlations of two microphone signals and uses a state machine for controlling the adaptation to avoid target-signal cancellation. Evaluation with sound data obtained in different acoustic environments demonstrates that the noise reduction by the proposed AMC is 3 dB better than that by the AMC based on the SNR estimate. Subjective listening tests show that the quality of the output signal by the proposed AMC is comparable to or even better than those by the conventional AMCs.

In this paper, we propose a lower bound for the minimum distance of [n,k] linear codes which are specified by generator matrices whose rows are k vectors of a given sequence of n linearly independent vectors over a finite field. The Feng-Rao bound and the order bound give the lower bounds for the minimum distance of the dual codes of the codes considered in this paper. We show that the proposed bound gives the true minimum distance for Reed-Solomon and Reed-Muller codes and exceeds the Goppa bound for some L-type algebraic geometry codes.

This paper deals with the problem of autoregressive (AR) spectral estimation from a finite set of noisy observations without a priori knowledge of additive noise power. A joint technique is proposed based on the high-order and true-order AR model fitting to the observed noisy process. The first approach utilizes the uncompensated lattice filter algorithm to estimate the parameters of the over-fitted AR model and is one-pass. The latter uses the noise compensated low-order Yule-Walker (LOYW) equations to estimate the true-order AR model parameters and is iterative. The desired AR parameters, equivalently the roots, are extracted from the over-fitted model roots using a root matching technique that utilizes the results obtained from the second approach. This method is highly accurate and is particularly suitable for cases where the system of unknown equations are strongly nonlinear at low SNR and uniqueness of solution from the LOYW equations cannot be guaranteed. In addition, fuzzy logic is adopted for calculating the step size adaptively with the cost function to reduce the computational time of the iterative total search technique. Several numerical examples are presented to evaluate the performance of the proposed scheme in this paper.

In this report, a design method of neural networks for limit cycle generator is described. First, the constraint conditions for the synaptic weights, which are given by the linear inequalities, are derived from the dynamics of neural networks. Next, the linear inequalities are solved by the linear programming method. The synaptic weights and other parameters are determined by the above solutions. Furthermore, neuro-based limit cycle generator is designed with analog electronic circuits and simulated by Spice. Finally, we confirm that our design method is efficient and practical for the design of neuro-based limit cycle generator.

A new adaptive multichannel filtering approach is introduced and analyzed in this paper. The technique is simpler and more appropriate than traditional approaches that have been addressed by means of groupwise vector ordering information. These filters are a two-stage filters based on rational functions (RF) using fuzzy transformations of the Euclidean and angular distances among the different vectors to adapt to local data in the color image. The output is the result of vector rational operation taking into account three fuzzy sub-function outputs. Simulation studies indicate that the filters are computationally attractive and have excellent performance such as edge and details preservation and accurate chromaticity estimation.

Simple and scalable device-modeling techniques for inductors and capacitors are described. All model parameters are calculated from geometric parameters of the device, process parameters of the technology, and a substrate resistance parameter. Modeling techniques for other devices, such as resistors, varactor diodes, pads and MOSFETs, are also described. Some simulation results using the proposed device-modeling techniques are compared with measured results and they indicate adequacy of the proposed device-modeling techniques.