TCP Redirection (TCP-R) is an extension of TCP, which maintains active TCP connections when the disconnection occurs due to IP address changes. In mobile computing environments, IP addresses may be changed frequently as the host moves across subnets or changes network devices. However, it is difficult for most stateful network applications to work continuously in that situation. There is much research to support such dynamics in the network layer, but these attempts in the IP layer tend to incur some complexity. This paper intends to investigate the end-to-end mobility support in the transport layer. We developed a simple redirection mechanism for TCP, which enables us to keep our working activities continuous without any intermediate agents for IP packet forwarding. We also show that TCP-R enables the intentional replacement of IP addresses, which is useful for certain network services. We implemented and evaluated a prototype of TCP-R. The measured performance indicates that TCP-R can realize continuous operation with minimal overhead and complexity.

This paper presents a network surveillance technique for detecting malicious activities. Based on the hypothesis that unusual conducts like system exploitation will trigger an abnormal network pattern, we try to detect this anomalous network traffic pattern as a sign of malicious, or at least suspicious activities. Capturing and analyzing of a network traffic pattern is implemented with a concept of port profiling, where measures representing various characteristics of connections are monitored and recorded for each port. Though the generation of the port profiles requires the minimum calculation and memory, they exhibit high stability and robustness. Each port profile retains the patterns of the corresponding connections precisely, even if the connections demonstrate multi-modal characteristics. By comparing the pattern exhibited by live traffic with the expected behavior recorded in the profile, intrusive activities like compromising backdoors or invoking trojan programs are successfully detected.

Under a contamination of background sound noises, it seems difficult especially in a real working situation to evaluate various type statistics of only an objective sound signal fluctuation. In many cases of the noise evaluation, some signal processing method have been employed to eliminate the effect of background sound noises by first measuring emitted sound levels. In this study, a new evaluation method of sound level fluctuation is proposed in principle on the basis of the measurement of heterogeneous physical quantity other than sound pressures or sound levels to eliminate the effect of background sound noises. Though the theoretical analysis on acoustical emission caused by a mechanical vibration seems very difficult in a working situation, the sound noise fluctuation emitted only from an objective sound source can be effectively evaluated through its related vibration measurement by employing a fairly unified stochastic method proposed on the basis of a generalized regression analysis between sound and vibration. Here, the regression coefficients are determined by employing the least squares error method to minimize the mean square of estimation error to illustrate well the sound data by means of vibration data. Finally, the effectiveness of proposed method has been experimentally applied to the sound noise evaluation of a jigsaw.

A compact new test structure using shift register circuits for extracting components of the capacitance matrix of the multi-layer interconnections has been proposed. An extraction method of the capacitance matrix is also presented. As a result of fabrication, capacitance values obtained by measurement are in good agreement with the numerical calculation. We also showed an estimation method of the measurement errors.

This paper proposes an adaptive microphone array using blind deconvolution. The method realizes an signal enhancement based on the combination of blind deconvolution, synchronized summation and DSA (Delay-and-Sum Array) method. The proposed method improves performance of estimation by the iterative operation of blind deconvolution using a cost-function based on the coherency function.

A new simple method for extracting the capacitance coupling coefficients of sub-0.5-µm flash memory cells is proposed. Different from the previously proposed methods, this method is not affected by a dopant profile of source region because a band-to-band tunneling current from the interface between the drain and the substrate is probed. Use of a reference device eliminates the necessity to make assumptions concerning the electron transport mechanism. Comparison with the other methods shows that the proposed method is simple and accurate.

Network applications such as FTP, WWW, Mirroring etc. are presently operated with little or no knowledge about the characteristics of the underlying network. These applications could operate more efficiently if the characteristics of the network are known and/or are made available to the concerned application. But network characteristics are hard to come by. The IP Performance Metrics working group (IETF-IPPM-WG) is working on developing a set of metrics that will characterize Internet data delivery services (networks). Some tools are being developed for measurements of these metrics. These generally involve active measurements or require modificationsin applications. Both techniques have their drawbacks. In this work, we show a new and more practical approach of estimating network characteristics. This involves gathering and analyzing the network's experience. The experience is in the form of traffic statistics, information distilled from management related activities and ubiquitously available logs (squid access logs, mail logs, ftp logs etc. ) of network applications. An analysis of this experience provides an estimate of the characteristics of the underlying network. To evaluate the concept we have developed and experimented with a system wherein the network characteristics are generated by analyzing the logs and traffic statistics. The network characteristics are made available to network clients and administrators by Network Performance Metric (NPM) servers. These servers are accessed using standard network management protocols. Results of the evaluation are presented and a framework for efficient operation of network operations, using the network characteristics is outlined.

Auctions are a critical element of the electronic commerce infrastructure. But for real-time applications, auctions are a potential problem - they can cause significant time delays. Thus, for most real-time applications, sealed-bid auctions are recommended. But how do we handle tie-breaking in sealed-bid auctions? This paper analyzes the use of multi-round auctions where the winners from an auction round participate in a subsequent tie-breaking second auction round. We perform this analysis over the classical first-price sealed-bid auction that has been modified to provide full anonymity. We analyze the expected number of rounds and optimal values to minimize communication costs.

This paper proposes a new robust adaptive beamformer applicable to microphone arrays. The proposed beamformer is a generalized sidelobe canceller (GSC) with a variable blocking matrix using coefficient-constrained adaptive filters (CCAFs). The CCAFs, whose common input signal is the output of a fixed beamformer, minimize leakage of the target signal into the interference path of the GSC. Each coefficient of the CCAFs is constrained to avoid mistracking. In the multiple-input canceller, leaky adaptive filters are used to decrease undesirable target-signal cancellation. The proposed beamformer can allow large look-direction error with almost no degradation in interference-reduction performance and can be implemented with a small number of microphones. The maximum allowable look-direction error can be specified by the user. Simulation results show that the proposed beamformer, when designed to allow about 20of look-direction error, can suppress interference by more than 17 dB.

We have investigated the operation of a reflection type magnetostatic wave signal-to-noise enhancer in detail. It has good enhancement characteristics, low insertion loss, and low operating power. It is also composed of a transducer using a ceramic substrate having a high dielectric constant and an LaGa-YIG film with low saturation magnetization to enable direct operation in the 400-MHz band (the IF band of current DBS receivers). Enhancement of 8 dB was achieved over a 40-MHz bandwidth. Although its operating frequency range depends critically on device temperature, we can compensate for the temperature dependence by adjusting the bias magnetic field. Experiments showed that the enhancer improved the received carrier-to-noise ratio by 2 to 3 dB, providing good noise reduction in DBS reception.

In a mobile computing environment, in which communication channels are limited and have low-bandwidths, mobile transactions are long-lived and frequently disconnected with their wireless network in processing. Such peculiarities of mobile transactions make existing transaction scheduling schemes inadequate and raise new challenging research problems. In this paper, we propose a new scheduling scheme called OTS/MT (Optimistic Timestamp Scheme for Mobile Transactions) for mobile transaction scheduling. OTS/MT is based on an optimistic approach that is suitable for low data contention, and prevents indefinite postponement and cascading delay which are major drawbacks of the existing optimistic concurrency control scheme and the timestamp ordering scheme. In addition, the OTS/MT algorithm is inherently a deadlock-free scheduling scheme. In order to schedule mobile transactions, OTS/MT postpones the detection of conflict between mobile transactions until transaction commit time to improve the performance deterioration of TO. In this paper, we attempt to show that this application of optimism to TO is justified by way of simulation.

A trinary-phased array, in which a phase quantization unit of phase shifters is 120 degrees is examined. The phase quantization unit of 120 degrees is the roughest value in practical phased array applications. Despite its rough phase quantization, the sidelobe level of less than -9 dB is attained by a genetic algorithm approach.

In order to reduce state explosion problem, techniques such as symbolic state space traversal and partial order reduction have been proposed. Combining these two techniques, however, seems difficult, and only a few research projects related to this topic have been reported. In this paper, we propose handling single place zero reachability problem of Petri nets by using both partial order reduction and symbolic state space traversal based on ZBDDs. We also show experimental results of several examples.

In Adleman's Function Field Sieve algorithm solving the discrete logarithm problem in a finite field, it is assumed that a random bivariate polynomial in the certain class is absolutely irreducible with high probability. In this letter we point out that if we use Cab type random polynomials then we always get absolutely irreducible polynomials. We can also simplify the calculation of a product of many rational functions on a curve that belongs to the field of definition by the use of a Cab curve.

Optical frontend and distributed amplifier IC modules, both containing GaAs heterojunction-bipolar-transistors (HBT), have been developed for 40 Gb/s optical receiver. To achieve high-speed operations, the elements in the modules including the IC and signal lines, were designed to achieve a wider bandwidth with lower electrical reflection. The influence of a bonding-wire inductance was taken into particular account in optimizing the parameters of the ICs. The optical frontend, consisting of a waveguide pin-photodiode and an HBT preamplifier IC, exhibits a transimpedance gain of 43 dBΩ and a bandwidth of 31 GHz. The distributed amplifier IC module achieves a gain of 9 dB and a bandwidth of 39 GHz. A 40-Gb/s optical receiver constructed with these modules exhibited a high receiver sensitivity of -28. 2 dBm for a 40-Gb/s optical return-to-zero signal.

In this paper, the bit error rate (BER) of 16 differential amplitude phase shift keying (16DAPSK) modems in future mobile communication system is derived analytically. The channel employed in this paper is the frequency-selective and fast Rayleigh fading channel, corrupted by cochannel interference (CCI) and additive white Gaussian noise (AWGN). Exact expressions for the probability distributions of the differential phase and amplitude ratio are derived for the BER calculation. The BER and optimum boundary are obtained for various channel conditions. In addition, the results for the BER in the presence of CCI are provided.

In this paper, we propose a method to detect a road sign from a road scene image in the daytime. In order to utilize color feature of sign efficiently, color distribution of sign is examined, and then color similarity map is constructed. Additionally, color similarity shown on the map is incorporated into image energy of an active net model. A road sign is extracted as if it is wrapped up in an active net. Some experimental results obtained by applying an active net to images are presented.

Recently, we proposed a low power consumption FIR switched-capacitor filter constructed with capacitors having capacitances in proportion to square roots of transfer function coefficient values. It is referred to as an FIR semi-parallel cyclic type (SPCT) filter. In this paper, we present IIR SPCT filter. It needs only a single operational amplifier, hence being low power consumption. The IIR SPCT filter has smaller total capacitance than one of the IIR parallel cyclic type (PCT) filter and better high frequency response than one of the IIR transfer function coefficient ratio (TCR) filter. As a whole, the IIR SPCT filter has middle performance of the IIR PCT and TCR filters for the total capacitance, the number of types of clock pulses, and high frequency response.

This paper describes an efficient SPICE netlist reduction method, which enables collective simulation of large circuits. The method reduces a SPICE netlist to only those devices which affect the simulation results. Parts of the netlist can be significantly reduced in size, with relatively discrepancies arising between the original SPICE simulation and the reduced SPICE simulation. The authors' reduction method is more general than previous works, since it reduces circuits using the features of MOS transistors. According to experimental results, reduction rates can range from 1/2 to 1/223. Depending on the reduction, the time taken time to run a SPICE simulation was reduced by between one and two oder of magnitude. Using this method and working on the reduced netlist, SPICE could even handle netlist for very large circuits which it could not ordinarily handle. The simulation error between the original SPICE simulation and the reduced SPICE simulation was about 3.5%.

SiGe HBTs with doping level inversion, that is, a higher dopant concentration in the base than in the emitter, are realized based on the double-polysilicon self-aligned transistor scheme by means of selective epitaxy performed in a production CVD reactor. The effects of the Ge profile in the base on the transistor performance are explored. The fabricated HBT with a 12-27% graded Ge profile demonstrates a maximum cutoff frequency of 88 GHz, a maximum oscillation frequency of 65 GHz, and an ECL gate delay time of 13.8 ps.