Recent advances in DSP systems

Some of the advances that have contributed to the realization of communication systems with programmable digital signal processors (DSPs) are described. DSP architectures are examined, covering the performance improvements resulting from advances in circuitry as well as in architecture. Architectural advances discussed are parallel processing, function generation, integrating analog circuits, and sigma-delta analog-to-digital conversion. DSP applications to high-speed modems, trellis-coded modulation, and echo cancellation are examined. The DSP implementation of a V.32 modem is described     

Recent advances in coherent optical fiber communication systems

Research and development of coherent optical fiber communications have been accelerated mainly because of the possibility of receiver sensitivity improvement reaching 20 dB, and partly because of the possibility of frequency-division multiplexing (FDM) with very fine frequency separation. In this paper, recent advances in the research on coherent optical fiber communication systems are reviewed, with emphasis on those reported in the past two years. The bit-error rate measurements so far reported are classified and investigated in four categories: PCM-ASK, PCM-FSK, PCM-PSK, and PCM-DPSK. The states-of-the-art of polarization-state stabilization techniques is also discussed.     

Recent advances in modeling response-time distributions in real-time systems

Real-time systems are an important class of process control systems that need to respond to events under time constraints, or deadlines. Such systems may also be required to deliver service in spite of hardware or software faults in their components. This fault-tolerant characteristic is especially critical in systems whose failure can cause economic disaster and/or loss of lives. This paper reports recent research in the area of analytical modeling of the three major characteristics of real-time systems: timeliness, dependability, and external environmental dependencies. The paper starts with a brief introduction to analytical modeling frameworks such as Markov models and stochastic petri nets. This is followed by an examination of advances in modeling response-time distributions, reliability, distributed messaging services, and software fault-tolerance in real-time systems.     

Recent advances in submarine optical fiber cable transmission systems in Japan

Submarine optical fiber cable transmission systems are promising successors to existing submarine coaxial cable systems. This paper will review the history and the state of the art of the submarine optical fiber cable transmission technology, and the submarine optical fiber cable transmission systems named FS-400M and OS-280M being developed by NTT and KDD, respectively, in Japan.     

Recent advances in the performance and reliability of InGaAsP LED's for lightwave communication systems

High radiance LED's are being exploited in lightwave applications where their low cost, wide temperature range of operation, and outstanding reliability outweigh the power and modulation advantages of injection laser diodes. Development activity and commercial offerings of LED's have been rapidly moving toward InGaAsP LED's to take advantage of the low attenuation and chromatic dispersion minimum at the 1.3-µm emission wavelength. This paper reviews recent advances in the performance, reliability, and system application of InGaAsP LED's.     

Reliability growth models for hardware and software systems based on nonhomogeneous Poisson processes: A survey

We summarize the reliability growth models for hardware and software systems described by a stochastic process, where the underlying stochastic process is assumed to be a nonhomogeneous Poisson process (NHPP). The background of reliability growth modelling based on an NHPP is surveyed. The Duane model, which was first postulated as a reliability growth model and is commonly used, is first explained. Secondly, the Weibull growth and modified Weibull growth models for hardware systems and the exponential type growth and gamma type growth models for error detection for software systems are discussed. The parameter estimates can be obtained by maximum likelihood estimation. Finally, the goodness-of-fit tests based on chi-square, Cramér-von Mises and Kolmogorov-Smirnov statistics are presented for the reliability growth models based on an NHPP.     

Recent advances in nonlinear optics for bio-imaging applications

Nonlinear optics, which is a subject for studying the interaction between intense light and materials, has great impact on various research fields. Since many s...     

Recent advances in rate control for video coding

In this paper, we review the recent advances in rate control techniques for video coding. The rate control algorithms recommended in the video coding standards are briefly described and analyzed. Recent advances, such as new concepts in rate-distortion modelling and quality constrained control, are presented. With these techniques, the rate control performance can be improved. The paper not only summarizes these recent rate control techniques but also provides explicit directions for future rate control algorithm design.     

Recent advances in fuzzy techniques for image enhancement

With the continued growth of multimedia and communications systems, the instrumentation and measurement fields have seen a steady increase in the focus on image data. Developing tools and techniques to enhance the quality of image data plays a very relevant role. Enhancement of noisy images, however, is not a trivial task. The filtering action should distinguish between unwanted noise (to be removed) and image details (to be preserved or possibly enhanced). Nonlinear filters based on fuzzy systems effectively complete this task, outperforming conventional methods. Fuzzy reasoning is very well suited to model the uncertainty that typically occurs when both noise cancellation and detail preservation represent very critical issues. Since 1992, the number of different approaches to fuzzy filtering has been progressively increasing. The goal of this article is to explain the basic principles of fuzzy filtering, focusing on a selection of the most significant methods     

Recent advances in process synthesis for semiconductor devices

Recently, work has been started on a new methodology, called process synthesis, that has the potential to revolutionize integrated circuit (IC) process design in the same way that ASIC and microelectronics manufacturing science and technology (MMST) revolutionized circuit design and factory operation. This paper provides an overview of process synthesis, discusses synthesis methodologies, potential roadblocks to execution of this strategy, and presents recent progress in developing this capability     

Recent advances in visible LED'S

The state of the art, including advances reported at the Specialist Conference on the technology of visible electroluminescent diodes, is reviewed.     

激光光学研究的进展

对激光光学研究的进展作了综述。提出一些在光束描述和传输变换中值得进一步研究的问题,并作了简略分析。     

Recent advances in magnetic resonance

The author describes some advances in magnetic resonance imaging which have been made in approximately the last two years. These are in general areas of improved speed of image acquisitions, improved spatial resolution, selective imaging of blood vessels, and reduction of image artifact     

Recent advances in cognitive communications

This article describes recent advances in cognitive communications. We combine the concepts of signal processing, communications, pattern classification, and machine learning to make dynamic use of the spectrum, such that the emanated signals do not interfere with the existing ones. Unlike other programs such as neXt Generation communications of the Defense Advanced Research Projects Agency, where radio scene analysis is performed to find the spectrum holes or the white space, we make use of the white, as well as the gray space for non- interfering signal transmission. We examine the possibility of employing machine perception and autonomous machine learning technologies to the autonomous design and analysis of air interfaces. The underlying premise is that a learning module will facilitate adaptation in the standard classification process so that the presence of new types of waveforms can be detected, features that best facilitate classification of the previously and newly identified signals can be determined, and waveforms can be generated by using the basis-set orthogonal to the ones present in the environment. Incremental learning and prediction allows knowledge enhancement as more snapshots of data are processed, resulting in improved decisions. Some of the contributions of this project include technological advances in signal detection, feature identification, signal classification, sub-space tracking, adaptive waveform design, machine learning, and prediction.     

Recent advances in the production

Emphasis has been directed toward consistent and reproducible fiber characteristics, among them optical attenuation, dispersion, dimensional tolerances, numerical aperture and strength. Actual performance of an optical communication system will depend upon control and reproducibility of these properties to small tolerances fiber-to-fiber. Strength considerations also have received increased emphasis because of the need for long length, strong fibers. Average tensile strength in excess of 1.4 × 10⁴ N/mm² can be routinely obtained as measured by short gage length test samples. However, the useful strength of a fiber is determined by the rare flaw distribution for the fiber. Improvements in the long length strength value will be realized through process improvements and control, as well as new coatings to preserve the inherent fiber strength through subsequent processing operations. Continuous in-line screen tests insure minimum tensile strength values for all fibers. Typical properties and tolerances for commercially available step and graded index fibers are presented and discussed relative to the significances of the properties.     

Recent advances in VLSI layout

The current status of VLSI layout and directions for future research are addressed, with emphasis on the authors' own work. Necessary terminology and definitions and, whenever possible, a precise formulation of the problems are provided. Placement and floorplanning for both the sea-of-gates and building-block designs are examined. The former emphasizes the connectivity specification, whereas the latter must also consider module shape and size. Global routing based on a method of successive cuts on a chip is discussed. This is a hierarchical top-down approach that is useful for both of the above designs. A two-dimensional detailed routing problem and the rip-up and rerouting problem are also discussed. The field of computational geometry and its application to layout-in particular, to gridless routing and compaction-are reviewed, and layout engines are considered     

New advances of high-level synthesis for efficient and reliable hardware design

The spectacular CMOS technology scaling will continue to evolve and dominate the semiconductor industry. This will lead to tens of billions of transistors integrated on a single chip by the year 2020. However, one significant problem is that the design productivity for complex designs has been lagging behind. In addition to several proposed techniques for dealing with the widening productivity gap, e.g., IP reuse and integration, virtual platform modeling, formal verification and others, high-level synthesis (HLS) has been touted as an important solution as it can significantly reduce the number of man-hours required for a design by raising the level of design abstraction. However, existing HLS solutions have limitations, and studies show that the design quality of HLS can be inferior compared to that of manual RTL design. In this paper, we will present a set of new techniques developed recently to drastically improve HLS solutions, which not only improve the traditional design metrics such as circuit performance and energy efficiency but also emerging metrics such as hardware security and robustness. We will also discuss how HLS can collaborate with other techniques to provide a holistic design methodology that can enable the delivery of high-quality designs with much less design cost and much faster time-to-market.     

Recent advances in long-wavelength semiconductor lasers for opticalfiber communication

A brief history of the semiconductor laser and a short tutorial on its basic operating principles are given. Some key criteria for semiconductor lasers to be used in advanced systems are discussed. Various advanced laser structures (including single-frequency, high-speed and wavelength tunable lasers, laser transmitter optoelectronic integrated circuits, and coherent receiver photonic integrated circuits) are presented together with their performance characteristics     

Recent advances in cellular wireless communications

Testimonies of “wireless catching up with wireline” have begun. An information superhighway system is envisioned to fulfill the plethora of demand for wireless communications and the need for multimedia networks with multiservice requirements. The revolution in this technology will eventually free us, as communication users, from being tied down to a particular fixed location in a telephone network to person-to-person communications, via pocket-sized terminals, at an affordable price. This article briefly surveys the state of the art, standards, and technological growth experienced in mobile cellular (terrestrial and satellite) communications since the days of the ingenious inventions of Alexander Graham Bell and Guglielmo Marconi, over a century ago. Subsequently, we describe some emerging technological trends that can improve the capacity of third-generation systems and future outlooks for PCS networks in the next millennium