协同集成设计环境的通信支持若干问题研究

首先提出了一种直接建立在现有CAD应用内核之上的进程间通信模型,并通过实验研究对此进行了验证。然后提出了支持协同集成设计的通信协议集的一种基本框架。最后研究了对工程中大规模复杂CAD图形数据进行协议映射和动态传输的基本方法。实践证明,比现有交换数据文件和传输应用界面方法,在网络通信的时间/空间效率上具有显著优势。*     

Tools for the computer-aided design of multigigahertzsuperconducting digital circuits

The realization of large integrated circuits depends upon the application of computer-aided design (CAD) tools. This paper summarizes the results of a survey of CAD tools targeting superconducting digital electronics. Five categories of tools: circuit simulators, circuit optimizers, layout tools, inductance estimators, and logic simulators are discussed in detail. Within each category, a comparison of several currently available CAD tools is presented, and a tool which has been adapted for use or developed at the University of Rochester is discussed in greater detail. In addition, tools for timing analysis as well as integrated design environments that permit the effective data interchange among various tools and support libraries of design models are discussed. Future tools for timing optimization, automated logic synthesis, and automated layout synthesis are shown to be necessary for the design of superconducting circuits at the very large scale of integration (VLSI) level of integration. Trends regarding changes in the requirements for effective CAD tools are discussed, and expected improvements to existing tools and features of new tools currently under development are presented     

线性ASIC和线性／数字ASIC的CAD／CAT实验性研究

ASIC(Application Specific Integrated Circuits),专用集成电路——随着微电子工业IC制造技术的发展和CAD/CAT工具的成功应用,产品迅速增加,其应用范围已深入到各行各业。线性ASIC,线性/数字混合型ASIC在整个ASIC领域的比例也在迅速增长,应用范围迅速扩大。在ASIC发展过程中,CAD/CAT技术起着关键的作用,国内外有较多的系统可供使用,但要充分发挥作用还需要结合IC制造工艺实践作大量实验性研完工作。本文结合我所具体情况和工作实践,讨论进行线性ASIC和线性/数字混合型ASIC的CAD/CAT实验性研究的内容,并介绍开展的有关工作。     

Advanced digital receiver principles and technologies for PCS

The synergy between digital radio communications and VLSI signal processing is revolutionizing the design of wireless terminals. Driving this synergy are certain fundamental paradigms in modern communication theory, digital signal processing, and VLSI design. The authors discuss the modern centers-of-gravity model, which they believe is emerging as the basis for the successful design and implementation of advanced digital communication systems. Central to this model are design principles that enable engineers to systematically derive digital receiver structures and explore algorithm and architecture trade-offs using sophisticated tools. Digital signal processing technology is critical in the implementation of these digital receiver structures efficiently. Finally, CAD tools for digital communications system design and design space exploration are shown to be of crucial importance in the efficient execution of these designs     

Enhancing the efficiency of digital control system using the diversity radio reception

Possibilities of enhancing the operation efficiency of a digital control system (DCS) in systems of space-diversity radio reception have been considered. The specified systems are simulated by a queuing system with different types of priorities. The main tasks of DCS synthesis were also determined.     

Simulation and modeling: simulating optical interconnects

The computer-aided design tool can be used in choosing design parameter values that help lower the cost and increase reliability. Good tools are also necessary to minimize the length of the design cycle to bring products to market in a timely manner. Some tools exist that can be used for simulating and designing optical interconnects, but they are intended for electronics and are used for lack of tools more suitable for their unique needs. Currently, no computer-aided design tools encompass all the simulation methodologies required to address the design needs of optical interconnects. After reviewing briefly the various CAD tools that are available, the authors discuss in more detail two tools developed recently: iSMILE (illinois Simulator for the Modeling of Integrated-circuit Level Elements), a CAD tool for the rapid development and simulation of new circuit-level optoelectronics models; and iFROST (illinois FibeR-optic and Optoelectronic Systems Toolkit), a high-level simulator of digital lightwave links     

Computer-aided design of analog and mixed-signal integratedcircuits

This survey presents an overview of recent advances in the state of the art for computer-aided design (CAD) tools for analog and mixed-signal integrated circuits (ICs). Analog blocks typically constitute only a small fraction of the components on mixed-signal ICs and emerging systems-on-a-chip (SoC) designs. But due to the increasing levels of integration available in silicon technology and the growing requirement for digital systems to communicate with the continuous-valued external world, there is a growing need for CAD tools that increase the design productivity and improve the quality of analog integrated circuits. This paper describes the motivation and evolution of these tools and outlines progress on the various design problems involved: simulation and modeling, symbolic analysis, synthesis and optimization, layout generation, yield analysis and design centering, and test. This paper summarizes the problems for which viable solutions are emerging and those which are still unsolved     

The DCS as a Universal Digital Cross-Connect System

Existing DCS (digital cross-connect system) technology performs a subset of the digital cross-connect functions required in telecommunications networks. It must be used in tandem with other cross-connection systems such as DSX's (digital signal cross-connect systems) and DF's (distributing frames). It is these two technologies which provide most of the interconnection functions for digital facilities and equipment from the interoffice, subscriber loop, and central office parts of a network. Hence, if the DCS is to serve as a more universal digital cross-connect system, it must be enhanced to provide functions now performed by DSX's and DF's. This paper proposes expansion of DCS functions to incorporate some (or all) of the capabilities of the DSX and DF at discrete bit rates of the digital transmission hierarchy. Functional requirements, technology alternatives, planning/engineering issues, and operations/maintenance considerations are discussed.     

Digital optical networks using photonic integrated circuits (PICs) address the challenges of reconfigurable optical networks

To reduce costs and simplify operations, carriers are deploying flexible optical networks that can be easily reconfigured and managed remotely. This article provides an overview of typical all-optical reconfigurable optical add/drop multiplexer (ROADM) systems and their associated network issues. We describe a novel digital optical network architecture based on digital ROADM systems, which use photonic integrated circuits (PICs) to overcome many of these issues. Digital ROADM systems use monolithic PICs to integrate over 60 discrete optical components, including lasers, modulators and detectors, into a single pair of optical components, allowing cost-effective optical-electrical-optical conversion at every node. This also allows key functions such as service reconfiguration, add/drop and protection to be implemented in the digital domain, and enables de-coupling of service provisioning from optical link engineering, termed bandwidth virtualization. Finally, key deployment, reliability and operational metrics for PIC-based digital ROADM systems are presented.     

基于SCA的软件无线电SoPC设计

软件通信体系架构为实现具有开放性、标准化、模块化的通用软件无线电平台提供了规范。为了实现无线通信系统的小型化,采用软硬件协同设计的方法构建了基于SCA的软件无线电SoPC系统,该系统实现了波形组件的动态配置和部署,以及硬件组件的部分重构。同时它具有效率高,体积小,功耗低,功能强的优点,具有很好的应用前景。     

A Position-Based Clustering Technique for Ad Hoc Intervehicle Communication

Intervehicle communication is a key technique of intelligent transport systems. Ad hoc networking in the vehicular environment was investigated intensively. This paper proposes a new clustering technique for large multihop vehicular ad hoc networks. The cluster structure is determined by the geographic position of nodes and the priorities associated with the vehicle traffic information. Each cluster elects one node as its cluster head. The cluster size is controlled by a predefined maximum distance between a cluster head and its members. Clusters are independently controlled and dynamically reconfigured as nodes move. This paper presents the stability of the proposed cluster structure, and communication overhead for maintaining the structure and connectivity in an application context. The simulation is performed with comparative studies using CORSIM and NS-2 simulators.     

The impact of SONET digital cross-connect system architecture ondistributed restoration

The viability of distributed control restoration using digital cross-connect systems (DCS) depends on its capability for restoring services within specified time requirements, and its economics for providing restoration compared to other alternatives. The authors report a Bellcore study for the impact of the DCS architecture on distributed restoration. This study concludes that currently proposed distributed control DCS self-healing schemes may not meet the 2 second restoration objective for large metropolitan local exchange carrier's networks, regardless of the distributed algorithm used, if the present DCS system architecture which uses serial message processing and serial path cross-connection remains unchanged. They also discuss several DCS architecture enhancement options, including a parallel processing/cross-connect DCS architecture, which may improve the service restoration time     

A passive protected self-healing mesh network architecture andapplications

The self-healing mesh network architecture using digital cross-connect systems (DCSs) is a crucial part of an integrated network restoration system. The conventional DCS self-healing networks using logical channel protection may require a large amount of spare capacity for network components (such as DCSs) and may not restore services fast enough (e.g., within 2 s). The authors propose a passive protected DCS self-healing network (PPDSHN) architecture using a passive protection cross-connect network for network protection. For the PPDSHN architecture, network restoration is performed in the optical domain and is controlled by electronic working DCS systems. Some case studies have suggested that the proposed PPDSHN architecture may restore services within a two-second objective with less equipment cost than the conventional DCS self-healing network architecture in high-demand metropolitan areas for local exchange carrier networks. The proposed PPDSHN architecture may apply to not only the centralized and distributed control DCS network architectures, but also asynchronous, SONET and ATM DCS networks. Transparency of line rates and transmission formats makes the PPDSHN network even more attractive when network evolution is a key concern of network planning     

Reconfigurable bandpass sigma–delta modulator with programmable NTF for low-IF multi-mode receivers

A new reconfigurable bandpass sigma–delta modulator (BPSDM) structure is proposed for low-IF multi-mode wireless systems. The proposed modulator can be reconfigured to operate in different signal bandwidths and at different signal-to-noise ratios by rearranging and optimizing the order of the noise transfer function of the loop while still maintaining stability. Compared with conventional multi-mode BPSDM, employing cascade structures and multi-bit sub-ADCs, the proposed modulator features many attractive advantages, such as (1) avoiding coefficient mismatch between analog and digital components in cascade structures, (2) avoiding DAC non-linearities that are otherwise introduced by commonly used dynamic element matching techniques, and (3) improving and varying the dynamic range performance while meeting the requirements of different wireless standards.     

A compact dual band planar branched monopole antenna for DCS/2.4-GHz WLAN applications

A compact dual band planar antenna for a digital communication system (DCS)/2.4-GHz WLAN application is presented. The two resonant modes of the proposed antenna are associated with various length of the monopoles, in which a longer arm contributes for the lower resonant frequency and a shorter arm for higher resonant frequency. The experimental results show that the designed antenna can provide excellent performance for DCS/2.4-GHz WLAN systems, including sufficiently wide frequency band, moderate gain, and nearly omnidirectional radiation coverage. The outcome of the experimental results along with the design criteria are presented in this letter.     

Mathematical analysis of dynamic channel selection in indoor mobilewireless communication systems

Dynamic channel selection (DCS) is an algorithm for flexible resource sharing in mobile radio systems. The digital enhanced cordless telecommunications (DECT) standard implements a version of DCS based on time as well as frequency multiplexing. In this paper, mathematical models are developed to evaluate the probabilities of channel availability, desired carrier power, and the carrier-to-interference ratio (CIR) for a constant traffic load. These results can be used to compute the call setup blocking probability. The models reported in this study are based on a decentralized DCS according to the DECT standard specifications. The results show that blocking due to availability of a channel (resource blocking), not interference blocking, generally is the most important factor in overall call blocking. Furthermore, it is seen that resource blocking is sensitive to the implementation of portable sets. Also, with homogeneous static traffic, this type of DCS ran be as good as fixed channel allocation (FCA) with respect to resource blocking