In this paper, we consider the problem of multicast routing and wavelength assignment (MC-RWA) in multi-fiber all-optical WDM networks. Two main network design system comprehensively investigated here are mesh and multi-ring designs. Given the multicast traffic demands, we present new ILP formulations to solve the MC-RWA problem with an objective to determine the minimal number of fibers needed to support the multicast requests. Unlike previous studies, our ILP formulations are not only capable of finding the optimal multicast routing and wavelength assignment pattern to the light-trees, but also finding the optimal light-tree structures simultaneously. Since broadcast and unicast communications are special cases of multicast communications, our ILP models are actually the generalized RWA mathematical models of optical WDM networks. In addition to proposing the ILP models, this paper takes two main issues affecting the network capacity requirement into account, that is, the splitting degree level of optical splitters and techniques of wavelength assignment to the light-trees. Three multicast wavelength assignment techniques studied in this paper are Light-Tree (LT), Virtual Light-Tree (VLT) and Partial Virtual Light-Tree (PVLT) techniques. Due to the NP-completeness of the MC-RWA problem, the ILP formulations can reasonably cope with small and moderate networks. To work with large networks, this paper presents alternative MC-RWA ILP-based heuristic algorithms for the PVLT and LT networks and develops lower bound techniques to characterize the performance of our algorithms. Using existing large backbone networks, numerical results are reported to analyze such aspects as multiple fiber systems, the benefits of using optical splitters and wavelength converters, and the capacity difference between the mesh and multi-ring designs. Finally, this paper provides an analysis of the influence of network connectivity on the network implementation under the constraints of mesh and multi-ring design schemes.

This paper proposes a bandwidth allocation algorithm and a demand accommodation algorithm guaranteeing utility max-min fairness under bandwidth constraints. We prove that the proposed algorithms can fairly split network resources among connections and achieve call admission control considering the fairness among different types of applications. We then formulate three different network design problems to maximize the total utility of all customers, the number of users accommodated in the network, and the average utility of the customers accommodated in the network. To solve the problems, we extend the conventional network design algorithms considering utility max-min fair share, and numerically evaluate and compare their performance. Finally, we summarize the best algorithms to design the utility max-min fair share networks considering the operation policy of network providers.

All-optical switching is of considerable interest, since it enables the construction of large-capacity networks with protocol- and bit-rate-independent transmission. In this paper, we determine the most desirable of three all-optical architectures for a backbone network, by comparing the following architectures: the wavelength-routed network, the slotted wavelength-routed network, and the optical burst switching network. After proposing an optical path accommodation algorithm that minimizes the total fiber length, we evaluate the total network cost in order to compare the availability of the first two architectures. We then compare the architectures in terms of the burst blocking probability in order to clarify the effectiveness of the third architecture.

Recently, there have been a number of studies on wavelength division multiplexing (WDM) systems designed to increase transmission capacity and flexibility. This has in turn made it necessary to design the optical loss for optical fiber networks over a wide wavelength range. However, there is no general optical loss design method that allows us to employ for an optical fiber network over a wide wavelength range. In this paper, we propose a novel optical loss design and estimation method based on multiple regression analysis and statistical loss design technology for designing new optical fiber networks and for upgrading those that have already been installed. We show that the method can be used for highly accurate optical loss design and estimation from the O- to the L-band (1260 nm to 1625 nm), except for the E-band, by using easily obtainable optical loss values at wavelengths of 1310 and 1550 nm, which are usually used for communication. Moreover, we also show that the accuracy of our proposed method can be improved by selecting proper additional predictor wavelengths.

A novel method is presented to the symbolic computation of Noise Figure (NF) of transistor circuits. Several computationally efficient macromodels of BJTs and MOSFETs by using nullors, are introduced. To demonstrate the suitability of the proposed method, the fully-symbolic expression of NF of a CMOS current-mirror is computed, and the total output noise-voltage is compared with HSPICE simulations. The calculated NF and the simulated noise are in good agreement. Finally, the method is extended to compute NF of a CMOS translinear circuit biased in weak inversion.

Even in embedded processors, the accuracy in a branch prediction significantly affects the performance. In designing a branch predictor, in addition to accuracy, microarchitects should consider area, delay and power consumption. We propose two techniques to reduce the power consumption; these techniques do not requires any additional storage arrays, do not incur additional delay (except just one MUX delay) and never deteriorate accuracy. One is to look up two predictions at a time by increasing the width (decreasing the depth) of the PHT (Prediction History Table). The other is to reduce unnecessary accesses to the BTB (Branch Target Buffer) by accessing the PHT in advance. Analysis results with Samsung Memory Compiler show that the proposed techniques reduce the power consumption of the branch predictor by 15-52%.

This paper presents a novel design procedure for class E oscillator. It is the characteristic of the proposed design procedure that a free-running oscillator is considered as a forced oscillator and the feedback waveform is tuned to the timing of the switching. By using the proposed design procedure, it is possible to design class E oscillator that cannot be designed by the conventional one. By carrying out two circuit experiments, we find that the experimental results agree with the calculated ones quantitatively, and show the validity of the proposed design procedure. One experimental measured power conversion efficiency is 90.7% under 6.8 W output power at an operating frequency 2.02 MHz, the other is 89.7% under 2.8 W output power at an operating frequency 1.97 MHz.

This paper proposes the design and implementation of a real-time image compressor using 2-Dimensional Discrete Wavelet Transform (2DDWT), which targets an FPGA as its platform. The image compressor uses Daubechies' bi-orthogonal DWT filters (9, 7) and 16-bit fixed-point data formats for wavelet coefficients in the internal calculation. The target image is NTSC 640240 pixels per field whose color format is Y:Cb:Cr = 4:2:2. We developed for the 2DDWT a new structure with four Multipliers and Accumulators (MACs) for real-time operations. We designed and used a linear fixed scalar quantizer, which includes the exceptional treatment of the coefficients whose absolute values are larger than the quantization region. Only a Huffman entropy encoder was included due to the hardware overhead. The quantizer and Huffman encoder merged into a single functional module. Due to the insufficient memory space of an FPGA, we utilized external memory (SDRAM) as the working and memory storage space. The proposed image compressor maps into an APEX20KC EP20K600CB652-7 from Altera and uses 45% of the Logic Array Block (LAB) and 9% of the Embedded System Block (ESB). With a 33 MHz clock frequency, the proposed image compressor shows a speed of 67 fields per second (33 frames per second), which is more than real-time operation. The resulting image quality from reconstruction is approximately 28 dB in PSNR and its compression ratio is 29:1. Consequently, the proposed image compressor is expected to be used in a dedicated system requiring an image-processing unit.

Software rejuvenation is a preventive and proactive solution that is particularly useful for counteracting the phenomenon of software aging. In this paper, we consider both the periodic and non-periodic software rejuvenation policies under different dependability measures. As is well known, the steady-state system availability is the probability that the software system is operating in the steady state and, at the same time, is often regarded as the mean up rate in the system operation period. We show that the mean up rate should be defined as the mean value of up rate, but not as the mean up time per mean operation time. We derive numerically the optimal software rejuvenation policies which maximize the steady-state system availability and the mean up rate, respectively, for each periodic or non-periodic model. Numerical examples show that the real mean up rate is always smaller than the system availability in the steady state and that the availability overestimates the ratio of operative time of the software system.

The purpose of this paper is to present a rapid prototyping flow for the development of a wireless LAN system. The proposed system flow that was used for the development of the prototype is based on the use of UML (Unified Modeling Language). The UML and its real-time extensions are used to help the development phases of the prototype, mainly in the specification, co-simulation and validation of the design. The target of the development that was carried out with the application of the UML-based methodology is the implementation of an access point for a HIPERLAN/2 wireless network. Apart from the presentation of the UML-based system design methodology the paper also presents the application of the methodology for the implementation of the system prototype, the detailed software development and the results of the development.

This paper discusses the orbital motion and elevation properties of a quasi-zenith satellite system using circular orbits. The satellites are deployed on inclined geosynchronous orbits with identical sub-satellite loci on earth. The satellites trace the locus at even intervals. This satellite system can provide mobile satellite communications and navigation services at very high elevations to middle-latitude regions. In general, the orbital parameters of the satellite system are determined by numerical simulation to maximize the minimum elevation angle in areas where satellite services are to be provided. However, an understanding of the properties of the orbit and consequent elevation properties are important for efficient constellation design. This paper formulates the orbital motion of inclined geosynchronous circular orbits, including the relative motion to the rotating earth. Although elliptical orbit constellations are also possible and can gain higher elevation, only circular orbits, which can be accurately formulated without using an analytically unsolvable Kepler's equation, are discussed in this paper. Elevation properties are evaluated using the geocentric angle between the sub-satellite point and an arbitrary point in the intended service area. This angle is a typical parameter that can be derived as a single-valued function of the elevation at a specific point. Optimum orbital parameters for an intended service area can be easily estimated without numerical simulation using the results of the evaluation described in this paper. These results can also be used to infer whether a circular-orbit constellation is applicable to an intended service area.

In this paper, two efficient VLSI architectures for biorthogonal wavelet transform are proposed. One is constructed by the filter bank implementation and another is constructed by the lifting scheme. In the filter bank implementation, due to the symmetric property of biorthogonal wavelet transform, the proposed architecture uses fewer multipliers than the orthogonal wavelet transform. Besides, the polyphase decomposition is adopted to speed up the processing by a factor of 2. In the lifting scheme implementation, the pipeline-scheduling technique is employed to optimize the architecture. Both two architectures are with advantages of lower implementation complexity and higher throughput rate. Moreover, they can also be applied to realize the inverse DWT efficiently. Based on the above properties, the two architectures can be applied to time-critical image compressions, such as JPEG2000. Finally, the architecture constructed by the lifting scheme is implemented into a single chip on 0.35 µm 1P4M CMOS technology, and its area and working performance are 5.005 5.005 mm2 and 50 MHz, respectively.

This letter proposes a low-power tournament branch predictor, in which the number of accesses to the branch predictors (local predictor or global predictor) is reduced. Analysis results with Samsung Memory Compiler show that the proposed branch predictor reduces the power consumption by 24-45%, compared to the conventional tournament branch predictor, not requiring any additional storage arrays, not incurring any additional delay and never harming accuracy.

Application area of mixed signal technology is currently expanded to digital communication, networking, and digital storage systems from conventional digital audio and video systems. Digital consumer electronics are emerged and their markets are extremely increased. Rapid progress of integrated circuit technology has enabled a system level integration on a SoC. Thus mixed signal SoC becomes a majority in LSI industry. Almost all the analog functions should be realized by CMOS technology on SoC, yet some difficulties such as a low transconductance, a large mismatch voltage, and a large 1/f noise should be solved. CMOS device has been considered as a poor device for the analog use, however in reality, it has attained a remarkable progress for analog applications. CMOS device has a variety of circuit techniques to address its own issues and also has an analog performance that increases rapidly with technology scaling. The mixed signal SoC needs a new development strategy and design methodology that covers from system level to device level for addressing tough needs for a shorter development time, a lower cost, and a higher design quality. The optimizations over analog and digital and over system to device must be established for the development success. Difficulty of low voltage operation of further scaled CMOS in analog circuits will be the most serious issue. This results in the saturation of performance and increase of cost. The system level optimization over analog and digital, digital calibration and compensation, and the use of sigma-delta modulation method will give us the solution.

A new approach to optical clock distribution utilizing optical waveguide interconnect technology is introduced. In this paper, we develop a new algorithm for design and optimization of embedded optical clock distribution networks for printed wiring boards. The optimization approach takes into account bending and propagation losses of optical waveguides. Less than 26.1 psec in signal timing skew is obtained for a signal flight time of 614.38 psec. About 15% reduction in optical power consumption is also obtained over clock nets routed with existing (optical) methods.

DNA Sequence Design Problem is a crucial problem in information-based biotechnology such as DNA computing. In this paper, we introduce a powerful design strategy for DNA sequences by refining Random Generator. Random Generator is one of the design strategies and offers great advantages, but it is not a good algorithm for generating a large set of DNA sequences. We propose a Two-Step Search algorithm, then show that TSS can generate a larger set of DNA sequences than Random Generator by computer simulation.

Connectedness oriented communication denotes a mode of communication in which the activities of communication are more important than the contents of communication. It is targeted at maintaining and enhancing human social relationships. As our lifestyles and societies are shifting along with the progress of Information Technology, communication media that are connectedness oriented will play an important role. In this paper we propose a media called FaintPop, which is an example of such new media that are suitable for connectedness oriented communication. It is a communication media designed for a community, with which the sense of connectedness can be shared among members. Furthermore, it provides a general overview of the communication activities occurring in the community. We discuss several principles and points in designing the media, especially about the interaction of the users. Results and findings from the experiment using the media are reported.

The utilization of EXOR gates often decreases the number of gates needed for realizing practical logical networks, and enhances the testability of networks. Therefore, logic synthesis with EXOR gates has been studied. In this paper we propose a new logic representation: an ESPP (EXOR-Sum-of-Pseudoproducts) form based on pseudoproducts. This form provides a new three-level network with EXOR gates. Some functional classes in ESPP forms can be realized with shorter expressions than in conventional forms such as the Sum-of-Products. Since many practical functions have the properties of such classes, the ESPP form is useful for making a compact form. We propose a heuristic minimization algorithm for ESPP, and we demonstrate the compactness of ESPPs by showing our experimental results. We apply our technique to some logic function classes and MCNC benchmark networks. The experimental results show that most ESPP forms have fewer literals than conventional forms.

As various mobile communication systems have developed, dramatically integrated wireless network, where users can communicate seamlessly via several wireless access systems, have become expected. At present, there are many studies of integrated wireless network, but no study of a network design method. Therefore, in this paper, we discuss a network design method for integrated wireless networks. Because of the handover procedure, the network design where adjacent base stations are connected to the same router, regardless of radio system type, is simply considered. However, in such a design, where mobile users crowd into a particular area and users' access to the base stations located there increases, the load of these accesses is centralized to the single router. To overcome this problem, we propose a new network design wherein the base stations of heterogeneous wireless communication systems, the service areas of which overlap, are connected to a different router. In the proposed network design, although users' accesses are concentrated on the base stations located in a particular area, users in that area can be assigned bandwidth of several upper links according to the access conditions of the base stations in neighboring areas. Finally, we show the excellent performance of the proposed design by simulation experiments.

This paper presents a Quiet-Noisy scan technique for low power delay fault testing. The novel scan cell design provides both the quiet and noisy scan modes. The toggling of scan cell outputs is suppressed in the quiet scan mode so the power is saved. Two-pattern tests are applied in the noisy scan mode so the delay fault testing is possible. The experimental data shows that the Quiet-Noisy scan technique effectively reduces the test power to 56% of that of the regular scan. The transition fault coverage is improved by 19.7% compared to an existing toggle suppression low power technique. The presented technique requires very minimal changes in the existing MUX-scan Design For Testability (DFT) methodology and needs virtually no computation. The penalties are area overhead, speed degradation, and one extra control in test mode.