In recent years, the concept of Quality of Service (QoS) has gained attention in the network research community and its extension towards delivering QoS level assurance to sensitive applications has generally been agreed to be crucial for the longevity and usability of the Internet. On the Internet, the Differentiated Services (DiffServ) architecture is a general framework for the differentiated treatment of traffic aggregates in the core network. However, DiffServ does not extend to end-to-end QoS assurance. In this paper, we propose a simple resource-brokering scheme operating over a hierarchically connected internetwork of administratively-independent DiffServ-capable domains that is a simplified model of the Internet. The proposed asynchronous, multi-agent resource-brokering scheme operates locally but avoids conflicts globally. In this way, the traffic control reflects the underlying structure of the internetwork, introduces only a localized complexity thus scaling up well, and permits independent policies between the interconnected domains.

We suggest the method to recover the 3D shape of an object by using a color image scanner which has three light sources. The photometric stereo is traditional to recover the surface normals of objects using multiple light sources. In this method, it usually assumes distant light sources to make the optical models simple. But the light sources in the image scanner are so close to an object that the illuminant intensity varies with the distance from the light source, therefore these light sources should be modeled as the linear light sources. In this method, by using these models and two step algorithm; the initial estimation by the iterating computation and the optimization by the non-linear least square method, not only the surface normal but also the absolute distance from the light source to the surface can be estimated. By using this method, we can recover the 3D shape more precisely. In the experimental results, the 3D shape of real objects can be recovered and the effectiveness of the proposed method is shown.

We propose an efficient, low cost, multicast ATM switch which is fair to all inputs. The switch consists of a novel copy network which creates unicast packets in a fair manner, followed by a network that routes packets to their correct Address Translation Tables (ATT's) and ultimately a unicast routing network which ensures sequencing. The copy and routing networks are based on deflection routing. We show that our switch requires O(log N) stages and can be designed for any arbitrarily low level of packet loss. The theoretical results are backed up by simulations. Switching elements in both the copying and routing networks have O(1) bit complexity, making the overall bit level hardware complexity of the network O(N log N). The latency of the switch is proportional to the number of stages O(log N). Unlike other existing copy networks, our copy network drops packets in a fair manner and hence can provide quality of service (QoS) support. The switch is output queued and allows the delivery of multiple packets to the same destination during a time slot.

Recently, demand on class-of-service (CoS) has known a great increase thanks to a set of real-time applications such as Internet Telephony service. Class-Based Queuing (CBQ) is considered as an efficient queuing mechanism to guarantee CoS. ALTQ is a widely used platform for realizing CBQ. In this paper, we verify through experiments that bandwidth control of CBQ/ALTQ contains overhead for fluctuating traffic. To avoid such an overhead, we introduce dynamic bandwidth allocation scheme for real-time traffic fluctuating within fixed ranges. In the light of the limited network resources, it quickly becomes obvious that when the traffic rate exceeds the maximum available bandwidth, arriving packets will be accumulated in the router queue. As a result, the traffic delay increases and the quality of real-time applications is degraded. To cope with such a problem, we revise the RED algorithm for a large amount of traffic and propose a new packet discard algorithm that uses bandwidth as a trigger. Experiment results show that our proposal outperforms the already existing packet discard algorithms (RED, DropTail) in providing lower delay/jitter services. We show the efficiency of our proposal using a real system.

DANSE (Dynamically Adaptive Networking Service Environment) is a new architecture for adaptive network service systems. In this paper, a framework for context-aware service construction based on DANSE architecture is presented. In DANSE, any hardware, software, information, and services that are available on a network are treated as network resources. DANSE coordinates the construction of an end user's service based on the user's requests and situation or context (i.e., user's location, schedule, co-workers, etc.). To provide users with satisfactory services, it monitors user context continuously and searches for network resources that are convenient for a target user. Moreover, it detects changes in user context and invokes service construction if needed. If the desired service is not available, alternative services are automatically constructed. With those capabilities, DANSE enables ubiquitous provision of services any time, anywhere.

Recently, code division multiple access scheme with time division duplex (CDMA/TDD) has drawn considerable attention as means to realize efficient wireless multimedia communications system. In this paper, we propose two time slot allocation algorithms for CDMA/TDD systems to efficiently accommodate multimedia traffic. Assuming a practical multiple cell environment and a multimedia service model which consists of several kinds of circuit-switched and packet-switched services with different quality of services (QoSs), we evaluate the average delay (average time from call generation to channel assignment) of the CDMA/TDD system with the proposed algorithms, and compare the performance with that of CDMA with frequency division duplex (CDMA/FDD) and time division multiple access with TDD (TDMA/TDD) systems. Our computer simulation results show that the CDMA/TDD system with one of the proposed algorithms, which can effectively avoid interference among users with different QoSs, can improve the average delay performance as compared with the other systems.

In this paper, we describe a frame synchronization method for bi-orthogonal modulation systems. In bi-orthogonal modulation systems, several bi-orthogonal sequences are used for data transmission. Frame synchronization in bi-orthogonal modulation systems is difficult because transmitted sequences can change every frame. In the proposed method, each bi-orthogonal sequence consists of two different inner sequences. Each bi-orthogonal sequence has the same arrangement of two different inner sequences. A receiver can track the frame timing by observing the arrangement of inner sequences. In this paper, we analyze the bit error rate performance that takes into account the tracking performance of a system we developed based on our method. The spectral efficiency of the proposed system in code division multiple access (CDMA) systems is also investigated. As a result, we found that the proposed system is effective in synchronous CDMA systems.

This paper investigates the optimum transmit-antenna-weight generation method for adaptive antenna array transmit diversity (AAA-TD) in the W-CDMA forward link: AAA-TD with beam and null steering (BNST), AAA-TD with beam steering (BST), or switched beam transmit diversity with fixed weights (SBTD-FW). The achievable BER performance after carrier frequency calibration in the transmit beam pattern is compared among the three methods assuming a different carrier frequency in a 2-GHz band with the carrier separation of 184.5 MHz based on computer simulations. The simulation results show that the achievable BER performance in the forward link using AAA-TD with BNST is almost identical to that using AAA-TD with BST when there are many more interfering users than there are array antennas, except for the special case when a small number of higher rate users exists in the reverse link. This is because by performing carrier frequency calibration, the directions of the beam nulls are shifted from the real directions of arrival (DOAs) of the interfering users. However, we also show that the required transmit Eb/N0 at the average BER of 10-3 using AAA-TD with BST is decreased by approximately 1.0 to 1.2 dB compared to that using SBTD-FW with 12 beams.

In this paper, we propose a frequency domain active noise control (ANC) system without a secondary path model. The proposed system is based on the frequency domain simultaneous perturbation (FDSP) method we have proposed. In this system, the coefficients of the adaptive filter are updated only by error signals. The conventional ANC system using the filtered-x algorithm becomes unstable due to the error between the secondary path, from secondary source to error sensor, and its model. In contrast, the proposed ANC system has the advantage not to use the model. In this paper, we show the principle of the proposed ANC system, and examine its efficiency through computer simulations.

This paper introduces fast methods for variable length decoding (VLD) and inverse quantization (IQ) on software MPEG-2 decoders by using Single Instruction stream Multiple Data stream (SIMD) type instructions for multimedia applications. With the VLD implementation, the VLD tables are made as small as possible so as to minimize missed cache accesses, and variable length codewords are decoded concurrently. With the IQ implementation, inverse quantization of the VLD results is performed in parallel. When these methods are used, combined clock cycles for VLD and IQ are roughly 30% shorter than those resulting from conventional methods, and this effect is especially pronounced for high bitrate streams.

Phase-based methods for estimating the frequency of a sinusoid have typically suffered from a threshold effect, where for signal to noise ratio (SNR) below the threshold, the mean squared error of the estimate rapidly increases. Furthermore, it is a significant problem that the threshold is considerably high and strongly depends on frequency. To overcome the difficulties, a Kalman-based sinusoidal estimator bank (KSEB) is proposed. In the derivation of the KSEB, a four-channel filter bank and decimation technique are effectively used. The computer simulation also demonstrates the superiority of the KSEB to the other frequency estimators.

This report describes a new methodology for the optimal placement of decoupling capacitors on the printed circuit board (PCB). This method searches the optimal position of decoupling capacitor so that the impedance characteristics at the power supply is minimized in the specified frequency range. In this method, the PCB is modeled by the PEEC method to handle the 3-dimensional structures and Krylov-subspace technique is applied to obtain efficiently the impedance characteristics in the frequency domain.

This paper described a new method to generate a spread spectrum clock for the purpose of EMI reduction. This method uses two phase-locked loops (PLL). The output of the first PLL is locked to its input of 14.318 MHz. The VCO in this PLL is used to produce 32 outputs with the same frequency and each with 11.25 degrees phase variation. A digital spread spectrum generator uses these 32 signals to generate the desired spread spectrum signal by phase hopping technique. These two circuits form a spread spectrum digital PLL (SSDPLL). The second PLL is configured as a conventional frequency synthesizer. It can be programmed to generate the desired frequencies. The second PLL also serves as a low pass filter of the output of the SSDPLL to smooth out frequency variation. This circuit was implemented with a 0.6 µm single poly CMOS process. The active areas of the SSDPLL and the synthesizer are 826396 µm2 and 790298 µm2, respectively. The total power consumption is 99 mW at 3.3 V supply. The peak power of the spread spectrum clock is reduced by 10 dBm at 14.318 MHz output with a 2.34% frequency spreading. The reduction of peak power increases with output frequency.

A digital noncoherent demodulation scheme is presented for reception of Gaussian frequency shift keying (GFSK) signals with small modulation index. The proposed differential demodulator utilizes oversampled signals to estimate the symbol timing and to compensate the frequency offset. The performance of the proposed receiver is evaluated in terms of the bit-error rate (BER). Numerical results show that the proposed demodulator provides performance comparable to that of conventional baseband differential demodulator, while significantly reducing the implementation complexity suitable for single chip integration with direct conversion radio frequency module. Finally the performance of the proposed receiver is improved by adding a simple decision feedback module.

We have developed a super-fast response OCB (Optically self-Compensated Birefringence) mode TFT-LCD by using capacitively coupled driving method (CC driving method). Response time with this driving method has been improved by the twice or more compared with that of a conventionally driven TFT-LCD. Even at a low temperature, 0 degree, this panel can response within one field time, 16.7 ms, between every gray scale levels. We developed a prototype OCB mode LCD with newly designed compensation films, that achieved a wide viewing angle characteristic of 160 degrees horizontally and 140 degrees vertically under the condition of that the contrast ratio exceeds 10:1.

In this paper, we present a new signal frequency estimation method based on the sinusoidal additive synthesis model. In the proposed method, frequencies in both the signal and noise are estimated with several delay times by using an expanded linear prediction (LP) method, and assuming that the signal is stationary and noise is unstationary in short record length. Frequencies in the signal are extracted according to their dependence on different delays. The frequency estimation can be accomplished with short record length even in the case where the number of frequency components in the signal is unknown. And it is capable of estimating the frequencies of a signal in the presence of noise. Furthermore, the proposed method estimates the parameters with less computation and high estimation accuracy. Simulation results are provided to confirm the effectiveness of the proposed method. The comparison of estimation accuracy between the proposed method and the analysis by synthesis (ABS) method is shown with the corresponding Cramer-Rao lower bound. And the frequency resolution of this method is also shown.

We examine diagnosis of processor array systems formed as two-dimensional grids, with boundaries, and either four or eight neighbors for each interior processor. We employ a parallel test schedule. Neighboring processors test each other and report the results. Our diagnostic objective is to find a fault-free processor or set of processors. The system may then be sequentially diagnosed by repairing those processors tested faulty according to the identified fault-free set. We establish an upper bound on the maximum number of faults that can be sustained without invalidating the test results under worst case conditions. We give test schedules and diagnostic algorithms that meet the upper bound as far as the highest order term. We compare these near optimal diagnostic algorithms to alternative algorithms--both new and already in the literature.

Recently, an efficient algorithm has been proposed for finding all solutions of systems of nonlinear equations using inverses of approximate Jacobian matrices. In this letter, an effective technique is proposed for improving the computational efficiency of the algorithm with a little bit of computational effort.

This paper presents an intelligent routing algorithm, called Q-Agents, which bases its actions only on the agent-environment interaction. This algorithm combines properties of three learning strategies (Q-learning, dual reinforcement learning and learning based on ant colony behavior), adding to them two further mechanisms to improve its adaptability. Hence, the proposed algorithm is composed of a set of agents, moving through the network independently and concurrently, searching for the best routes. The agents share knowledge about the quality of the paths traversed through indirect communication. Information about the network and traffic status is updated by using Q-learning and dual reinforcement updating rules. Q-Agents were applied to a model of an AT&T circuit-switched network. Experiments were carried out on the performance of the algorithm under variations of traffic patterns, load level and topology, and with addition of noise in the information used to route calls. Q-Agents suffered a lower number of lost calls than two algorithms based entirely on ant colony behavior.

This paper proposes an automatic dispersion equalization system using extracted clock power monitoring in order to facilitate the field installation of high-speed time-division multiplexed (TDM) systems over existing fiber cables. The proposed scheme adjusts the dispersion of a variable-dispersion equalizer so as to maximize the extracted clock power level. This scheme has a simple configuration, needs no communication channel between the transmitter and the receiver, and is sensitive to parameters such as initial chirping and fiber input power. The clock power dependence on the fiber dispersion is theoretically analyzed assuming that the return-to-zero (RZ) format is used and that pulse broadening is small compared to the bit duration. We show that the clock power is maximized when the dispersion-induced waveform distortion is minimized. Numerical simulations show that the proposed scheme is effective with the non-return-to-zero (NRZ) format and for the case that the optimum total dispersion deviates from zero due to initial and/or self-phase modulation (SPM)-induced chirping. The operation of the proposed automatic equalization system is experimentally confirmed in 20-Gbit/s transmission using both RZ and NRZ formats. Moreover, a 40-Gbit/s transmission experiment over 200 km of dispersion-shifted fiber (DSF) is successfully demonstrated using the proposed equalization scheme.