Network survivability is one of the most pivotal issues in optical WDM networks. In particular, if a conduit is cut, approximately 16 terabits per millisecond can be lost in recent technology. A huge loss even by a single conduit failure fatally damages the performance and operation of the whole network. In this paper, we propose a new heuristic algorithm, called the Generalized Minimum-Cost (GMC) selection algorithm, to choose a pair of working and backup path which firstly minimizes total number of required wavelengths of working and backup path and secondly distributes lightpath request traffic into whole network links, if there are several pairs to require the same number of minimum wavelengths, in order to achieve load-balancing effect. GMC selection algorithm contains several formulas to get Working and Backup path Reservation Cost (WBRC) which can be obtained through heuristic GMC function. By using WBRC, our GMC selection algorithm achieves superior performance compared to the current Combined Min-Cost (CMC) selection algorithm and random selection algorithm in terms of the amount of wavelength consumption and blocked lightpath requests, especially on the relatively less-connected New Jersey LATA and 28-node US networks. Furthermore, we suggest a maximum number of non-blocked lightpath requests against single link failure in simulated networks for network operators to consider acceptable maximum traffic on their networks, so that they can provide 100% restoration capability in a single link failure without lightpath request blocking. We also analyze the complexity of the GMC selection algorithm and verify that the complexity of the GMC selection algorithm is lower than that of the CMC selection algorithm if the number of lightpath requests is sufficiently large.

Broadening the frequency bandwidth of antennas has been one of the major subjects concerning antenna design technologies. Two of the major subjects for microstrip antennas, which appeared in the 1970s, have also been the broadening of the frequency bandwidth and the sharing of multifrequency bands. In this paper, we describe the broadband and multiband techniques of printed antennas, and show the configurations of realized broadband and multiband antennas and their characteristics. Here, resonant-type microstrip antennas, planar monopole antennas, fractal antennas and ultra-wideband printed antennas are introduced. The optimum design techniques using a genetic algorithm are introduced for developing broadband and multiband printed antennas. The usefulness of this method is verified by the simulation and experimental results of the fabricated planar monopole antenna which has ultrawide-band characteristics.

Among recent trends in Quality of Service (QoS) provisioning in the Internet is the Differentiated Services Architecture, termed DiffServ. The successful deployment of Diffserv to provide a premium QoS guarantees to network traffic requires an effective admission control mechanism, which needs to be scalable and relatively simple to implement. In this paper we present a QoS network framework with novel and effective measurement-based resource management and admission control mechanisms. The mechanism is based on the characteristics of measured arrival and departure traffic. Those characteristics are captured via a passive monitoring. We implement the mechanism at the edge routers of a DiffServ Domain. The admission control mechanism is only executed at the edge routers and doesn't require any signaling between inner routers. The mechanism does not depend on the underlying network topology or any specifications of the cross traffic present in the domain. Therefore the mechanism is scalable. In addition, the proposed approach does not require any traffic policing mechanism at the entrance of the network. This approach can provide the statistical QoS guarantees to a variety of service classes within a DiffServ domain. We show that the proposed framework can provide a high degree of network resource sharing among multiple traffic classes while satisfying their QoS requirements. To evaluate the effectiveness of the proposed framework, we perform a set of simulations on a number of bursty video traffic sources.

In this paper, a cycle-based network recovery method for optical mesh networks is studied. The study in this paper concentrates on improving two performance requirements on network recovery: efficient spare resource utilization, and robustness for multiple failures. The proposed method uses multiple ring-covers and performs distributed link restoration using preplanned logical cycles embedded in physical mesh topologies. This method provides fast and simple recovery operation by exploiting the characteristics of ring topology and also provides efficient resource utilization by using multiple backup paths per link to improve the sharability of overall spare resources in the networks. With this method, layered reliability can be provided to network services by enabling priority-based robustness against multiple failures. The performance results reveal the trade-off between the resource efficiency for single failure and the robustness for multiple failures, and show the preconfiguration of a few logical cycles per link can provide enhanced resource efficiency and priority-based hierarchical robustness.

This paper aims to improve the performance of the soft canceller followed by simplified minimum mean-square error (SC/S-MMSE) turbo receiver for multiple-input and multiple-output space-division multiplexing/orthogonal frequency division multiplexing (MIMO-SDM/OFDM) transmission; it performs iterative parallel soft interference cancellation and MMSE filtering, and stream-wise soft-input and soft-output decoding. For this aim, we newly introduce two detection techniques: 1) serial interference cancellation, and 2) cyclic redundancy check (CRC)-assisted interference cancellation and MMSE filter tap computation. Various computer simulations are conducted to evaluate the performance enhancement obtained via the use of the two detection techniques. The computer simulation results show that this paper's proposed serial SC/S-MMSE turbo receiver with CRC achieves frame error rate (FER) performance gain over existing MIMO receivers (MMSE receiver, V-BLAST receiver, parallel SC/MMSE-matched filter (MF) turbo receiver, and parallel SC/S-MMSE turbo receiver) for QPSK, 16QAM and 64QAM modulation while keeping the comparable complexity order.

Single cell reuse of the same frequency, which is possible in DS-CDMA cellular systems, yields the option of site diversity to increase link capacity. In this letter, a generalized case of site diversity transmission is considered where multiple base stations (BS's) are involved in weighted transmissions with constant total transmit power to a target mobile station (MS). A general equation of conditional bit error rate (BER) is derived based on the model of weighted transmissions combined with antenna diversity reception and rake combining. It turns out theoretically that the optimum set of weights to maximize forward link capacity makes site selection diversity transmission (SSDT) the best performer. This theoretical analysis is confirmed by performance evaluation based on the Monte-Carlo simulation.

This paper presents a closed form expression of an exact average bit error rate (BER) for a time-division duplex (TDD) transmit diversity scheme employing maximal ratio combining (MRC) over time selective flat Rayleigh fading channels. In the proposed analysis, the feed back delay which degrades the BER performance is taken into account. The results are generally applicable to an arbitrary modulation scheme, as well as an arbitrary number of transmitting branches. To confirm the validity of the proposed analysis, the theoretical results are compared with the simulated ones.

This paper proposes a new angular measurement system to a moving target in the presence of clutter. We apply MUSIC (MUltiple SIgnal Classification) to the outputs of a Doppler filter bank consisting of quadrature mirror filter (QMF). The comparison between QMF and the short time Fourier transform (STFT) as a preprocessor of MUSIC is also discussed. DOA estimation performance by QMF-MUSIC is nearly equal to that of STFT-MUSIC. On the other hand, QMF-MUSIC overcomes STFT-MUSIC in the aspect of computational cost. In a specific example in this paper, the proposal QMF bank by Daubechies (4th order) wavelet requires 80% fewer the number of multiplications and 25% fewer the number of additions than the FFT-based STFT filter bank.

In this paper, a detailed model of a hybrid dual-stage Raman/erbium-doped fiber (EDF) amplifier is presented. This model takes into account the impact of double Rayleigh backscattering (DRB) noise, amplified spontaneous emission (ASE) noise and Kerr-nonlinearity induced impairments in the amplification process. Using this model, we present a comprehensive analysis of the operation of hybrid dual-stage Raman/EDF amplifiers under above impairments. We show that under fixed total gain conditions for the amplifier module, high Raman gain causes the introduction of increased DRB noise to the amplified signals whereas low Raman gain causes the introduction of high ASE noise power through EDF amplifier. Therefore a balance between the Raman amplifier gain and EDF amplifier gain is required for optimal operation. These observations are then combined to show an optimization process, which could be applied to improve the design of hybrid dual-stage Raman/EDF amplifiers.

This paper proposes an iterative parallel genetic algorithm with biased initial population to solve large-scale combinatorial optimization problems. The proposed scheme employs a master-slave collaboration in which the master node manages searched space of slave nodes and assigns seeds to generate initial population to slaves for their restarting of evolution process. Our approach allows us as widely as possible to search by all the slave nodes in the beginning period of the searching and then focused searching by multiple slaves on a certain spaces that seems to include good quality solutions. Computer experiment shows the effectiveness of our proposed scheme.

In 2002, Zhu et al. proposed a password authenticated key exchange protocol based on RSA such that it is efficient enough to be implemented on most of the target low-power devices such as smart cards and low-power Personal Digital Assistants in imbalanced wireless networks. Recently, YEH et al. claimed that Zhu et al.'s protocol not only is insecure against undetectable on-line password guessing attack but also does not achieve explicit key authentication. Thus they presented an improved version. Unfortunately, we find that YEH et al.'s password guessing attack does not come into existence, and that their improved protocol is vulnerable to off-line dictionary attacks. In this paper we describe our observation in details, and also comment for the original protocol on how to achieve explicit key authentication as well as resist against other existent attacks.

Spring-mass systems are widely used in computer animation to model soft objects. Although the systems can be numerically solved either by explicit methods or implicit methods, it has been difficult to obtain stable results from explicit methods. This paper describes detailed discussion on stabilizing explicit methods in spring-mass simulation. The simulation procedures are modeled as a linear digital system, and system stability is mathematically defined. This allows us to develop theories of simulation stability. The application of these theories to explicit methods allows them to become as stable as implicit methods. Furthermore, a faster explicit method is proposed. Experiments confirm the theories and demonstrate the efficiency of the proposed methods.

Dynamic power supply noise measurements with resolutions of 100 ps and 100 µV for 100 ns and 1 V ranges are performed at various operating frequencies up to 400 MHz on multiple points in a low power register file and SRAM for product chips by using on-chip noise detectors. The measurements show that the noises are clearly emphasized in frequency domains by the interaction of circuit operations and bias network's AC transfers. A proposed design methodology that covers a fast SPICE simulator and parasitic extractors can predict dynamic noises from power supplies, ground, well, and substrate interactions to provide robustness to the design of low power body bias control circuitry.

Anycast refers to the transmission of data from a source node to (any) one member in the group of designed recipients in a network. When the physical network and the set of anycast requests are given, the WDM anycast routing problem (WARP) is to find a set of light-paths, one for each source, for anycasting messages to one of the member in the anycast destination group such that not any path using the same wavelength passes through the same link. The goal of the WARP is to minimize the number of used wavelengths. In this paper, the WARP is formulated and studied, since WARP is NP-hard, several heuristic algorithms and a hybrid method which combines heuristic and simulated annealing techniques are proposed to solve it. These algorithms are used to find the close-to-optimal solution. Simulated results show that the proposed algorithms are able to achieve good performance.

This paper presents an approach of logic mapping into LUT-Array-Based PLD where Boolean functions in the form of the sum of generalized complex terms (SGCTs) can be mapped directly. While previous mapping approach requires predetermined variable ordering, our approach performs mapping and variable reordering simultaneously. For the purpose, we propose a directed acyclic graph based on the multiple-valued decision diagram (MDD) and an algorithm to construct the graph. Our algorithm generates candidates of SGCT expressions for each node in a bottom-up manner and selects the variables in the current level by evaluating the sizes of SGCT expressions directly. Experimental results show that our approach reduces the number of terms maximum to 71 percent for the MCNC benchmark circuits.

In this paper, a Dynamic Voltage and Frequency Management (DVFM) scheme introduced in a microprocessor for handheld devices with wideband embedded DRAM is reported. Our DVFM scheme reduces the power consumption effectively by cooperation of the autonomous clock frequency control and the adaptive supply voltage control. The clock frequency is controlled using hardware activity information to determine the minimum value required by the current processor load. This clock frequency control is realized without special power management software. The supply voltage is controlled according to the delay information provided from a delay synthesizer circuit, which consists of three programmable delay components, gate delay, RC delay and a rise/fall delay. The delay synthesizer circuit emulates the critical-path delay within 4% voltage accuracy over the full range of process deviation and voltage. This accurate tracking ability realizes the supply voltage scaling according to the fluctuation of the LSI's characteristic caused by the temperature and process deviation. The DVFM contributes not only the dynamic power reduction, but also the leakage power reduction. This microprocessor, fabricated in 0.18 µm CMOS embedded DRAM technology achieves 82% power reduction in a Personal Information Management scheduler (PIM) application and 40% power reduction in a MPEG4 movie playback application. As process technology shrinks, the DVFM scheme with leakage power compensation effect will become more important realizing in high-performance and low-power mobile consumer applications.

We propose a novel approach for designing a low power datapath in wireless communication systems. Especially, we focus on the digital FIR filter. Our proposed approach can reduce the power consumption and the circuit area of the digital FIR filter by optimizing the bitwidth of the each filter coefficient with keeping the filter calculation accuracy. At first, we formulate the constraints about keeping accuracy of the filter calculations. We define the problem to find the optimized bitwidth of each filter coefficient. Our defined problem can be solved by using the commercial optimization tool. We evaluate the effects of consuming power reduction by comparing the digital FIR filters designed in the same bitwidth of all coefficients. We confirm that our approach is effective for a low power digital FIR filter.

A novel CMOS LC oscillator architecture combining an LC tuned oscillator and a ring structure is presented as a new design topology to deliver improved phase noise for multiphase applications. The relative enhancement in the phase noise is estimated using a linear noise modeling approach. A three-stage LC-ring oscillator fabricated in a 0.6 mm CMOS technology achieves measured phase noise of -132 dBc/Hz at 600 kHz offset from a 900 MHz carrier and dissipates 20 mW with a 2.5 V power supply.

Programmable Logic Controller (PLC) has been widely used in the industrial control. Inherently, the PLC-based system is a class of Hybrid Dynamical System (HDS) in which continuous state of the plant is controlled by the discrete logic-based controller. This paper firstly presents the formal algebraic model of the PLC-based control systems which enable the designer to formulate the various kinds of optimization problem. Secondly, the optimization problem of the 'sensor parameters,' such as the location of the limit switch in the material handling system, the threshold temperature of the thermostat in the temperature control system, is addressed. Finally, we formulate this problem as Mixed Logical Dynamical Systems (MLDS) form which enables us to optimize the sensor parameters by applying the Mixed Integer Programming.

In this paper a novel dielectric resonator (DR) bandpass filter (BPF) with flexible arrangement of attenuation poles is proposed. This DR filter is similar to a conventional DR filter except adding a microstrip line below a DR, which not only shifts the location of attenuation poles, but also improves skirt characteristics. The duplexer with the proposed DR BPF has been yielded better isolation and sharper skirt behavior than that with a conventional DR filter. The implemented duplexer has shown a good performance and been well agreed with the simulation.