Protocols for ATM access networks

The development and standardization of ATM (asynchronous transfer mode) and signaling protocols for BISDN (broadband integrated services digital network) are considered. A view of both ATM and signaling protocols in which the key design guideline is service flexibility is presented. The approaches suggested are intended to create a service-independent broadband facility that is also sensitive to both service performance and network efficiency. Key issues are raised that will require serious consideration by standards groups, manufacturers, and service providers as BISDN moves toward production     

The development of broadband signalling platforms

Mao Zedong once said: "All genuine knowledge originates in direct experience." This paper describes the experiences gained through a range of development projects, all concerned with the design, development, demonstration and maintenance of real broadband signalling systems. The authors have participated in the development of a variety of systems offering broadband capabilities, all of which support some form of broadband signalling between the service user and the service provider. The process of designing and building such systems can provide invaluable insights into issues such as development methods, signalling performance, programming interface definitions, etc, none of which are apparent from purely paper-based studies or through the standards specification process.This 'coal-face' experience covers both collaborative as well as internal BT projects, with each system being subject to a wide variety of service requirements. In addition, the period of work covered by the developments described in the paper encompasses broadband signalling systems that on the one hand predate the published ITU-T standards on broadband ISDN systems and on the other include a comprehensive testbed supporting an interworking set of broadband signalling interfaces based on the appropriate signalling standards defined by both the ATM Forum as well as the ITU-T.     

Access to cable TV systems offering broadband service in the UnitedStates

Cable TV companies are in the lead in deploying broadband (and their own Internet service) to American homes. Should cable broadband networks be required, just as telephone networks have been for years, to offer their broadband customers “equal” or “reasonable” access to all Internet services? This article does not take sides. Rather, it lays out the basic facts and both sides' arguments. The article sheds light on a battle that has produced, so far, mostly a lot of heat     

Broadband cylindrical antenna with continuous resistive and concentrated capacitive loadings

A broadband cylindrical antenna with continuous resistive and concentrated capacitive loadings was constructed and investigated theoretically and experimentally. The antenna was found to have very good broadband properties, both in admittance and radiation pattern, and an efficiency considerably higher than that of purely resistive broadband cylindrical antenna.     

掺铒光纤ASE宽带光源的实验研究

掺铒光纤ASE源是一种优良的宽带光源,受到人们广泛关注.实验研究了掺铒光纤ASE宽带光源单、双程结构后向ASE输出光谱特性,当泵浦光中心波长为1480 nm时,分别考察了掺铒光纤长度、泵浦光功率对后向ASE输出平坦区间宽度和平坦度的影响.通过对两种结构下后向ASE输出光谱的分析比较发现,双程结构在L波段长波长处,尤其是1570～1620 nm波长范围,功率显著提升,从而使得ASE光谱的平坦区间宽度增大,平坦度提高.所得实验结果将为掺铒光纤ASE宽带光源的研制提供依据.     

Subcarrier multiplexed lightwave systems for broad-banddistribution

Microwave subcarrier multiplexing (SCM) is an important approach to the design of lightwave systems for broadband distribution. Recent progress in the design and performance of both analog and digital multichannel SCM systems is reviewed. The application of broadband SCM systems to both passive and optically amplified distribution networks is discussed. The discussion covers the general features of SCM systems; the electrooptic components that have been used in the system experiments described here, including laser intensity noise and noise due to intermodulation products; the carrier-to-noise ratio requirements; some multichannel FM systems experiments; and a 20-channel digital systems experiment; and a hybrid system carrying 60 FM SCM channels plus a 100-Mb/s baseband digital channel. Several approaches to broadband subscriber distribution networks are analyzed     

Signaling challenges in video dial tone networks

Residential broadband networks present new signaling challenges as compared to the more traditional telephony networks. Access signaling protocols such as DSM-CC and Q.2931 for ATM, are evolving to meet these challenges. A desirable outcome will be a solution that supports seamless interworking among the newer video applications and the more traditional applications. First we examine the new requirements that arise when considering control of VDT networks. We then provide a brief review of the capabilities and development status of each protocol. Finally, we examine possible evolution paths for the development of broadband signaling. Our primary objective is to describe a signaling evolution path that integrates the requirements of both business and residential broadband networks, thus allowing partial or total sharing of network resources in support of both types of applications     

223～235 MHz频段离散载波聚合宽带系统频率使用可行性分析

为提高223~235 MHz频段频谱的使用效率,满足行业用户宽带应用需求,在该频段引入了离散窄带载波聚合宽带系统。为解决系统间电磁兼容问题,对宽带系统和带内窄带无线数据传输系统进行了单站干扰分析和集总干扰分析,还对宽带系统和带外广播电视系统进行了确定性计算干扰分析。最后,基于干扰计算结果提出了频率使用的可行性建议。     

Exact solution for the characteristic impedance of rectangularcoaxial cone transmission line

The exact and approximate expressions for the characteristic impedance of a rectangular coaxial cone transmission line are obtained using the conformal mapping method. The formula is exact and simple, so, it enables the characteristic impedance of a broadband transverse electromagnetic (TEM) cell to be calculated accurately and easily. This broadband TEM wave cell, has increasing applications in both electromagnetic interference and electromagnetic compatibility measurements     

High speed integrated electronics for communications systems

The functions necessary in broadband communications systems at speeds above 50 Mb/s are discussed. The types of components and functionality that are needed for access to networks and for the transmission and routing of traffic within networks are identified. Integrated circuit components used for customer-network access, network multiplexing, and switching are reviewed. It is shown that currently available digital VLSI technology is capable of achieving both the speeds and the levels of integration necessary to allow broadband network access even to residential subscribers     

走向宽带

发展宽带是国家的长远需要,既能应对当前的国际金融危机,又着眼长远,是适应未来发展需要、走向信息社会的重要战略。宽带也是全业务运营的关键,运营商必须从固定接入与移动接入双管齐下地打造全业务宽带接入。中国需要制订国家宽带发展战略,来引领中国宽带基础设施的建设。     

Broadband high-efficiency circularly polarized active antenna and array for RF front-end application

This paper presents a broadband high-efficiency circularly polarized (CP) active integrated antenna, and a broadband CP active array at 2 GHz. To realize the broadband CP antenna, a circular patch is aperture coupled by crossed slots in the ground plane, which are fed by an L-shaped microstrip feed line below the ground. The antenna is designed to serve the functions of both a radiator and a harmonics-terminated load for class-E high-efficiency power-amplifier (PA) integration. The broadband CP active antenna is realized by directly integrating the broadband CP antenna with the class-E PA. It achieves a 9% bandwidth (1.84-2.01 GHz) for axial ratio (AR) below 3 dB, and a 12% bandwidth for power-added efficiency (PAE) over 60%. To form the broadband CP active array, four active antenna elements are sequentially rotated, and each element is directly integrated with broadband class-E PA. A low-cost printed-circuit-board technology is employed in fabrication and a pseudomorphic high electron-mobility transistor is used. A peak drain efficiency of 71.5% for the class-E amplifier is measured at 1.95 GHz. The active array achieves a peak-effective radiated power of 39.7 dBm, and PAE is over 50% within a 22.6% bandwidth (1.72-2.16 GHz). The AR is below 3 dB over a 27% bandwidth (1.72-2.26 GHz).     

Modeling and design of GaAs MESFET control devices for broad-bandapplications

Closed-form expressions are developed for the small-signal parameters of broadband GaAs control MESFETs. The theoretical conducting-state resistance and nonconducting-state capacitance are compared with experimental data and demonstrate the usefulness of the models. Additionally, the power-handling capability of these devices is considered and the various limitations in both conducting and nonconducting states are described. The models show that self-aligned-gate devices (SAGFETs) have a broadband cutoff-frequency figure of merit as much as twice that of conventional MESFETs, although the voltage-handling capability of the SAGFET is considerably inferior     

Wireless Local Loop

Wireless local loop systems are available to provide both broadband and narrowband services to customers. Narrowband systems are generally either based on cordless or mobile standards, or a manufacturer's proprietary technology. They are generally designed to offer voice-band services although some are capable of delivering ISDN. The broadband systems are either circuit or cell based. These systems usually operate at millimetre-wave frequencies where a line-of-sight path is required between the customer and a central base-station. Services are typically leased line, ATM and LAN interconnect.     

ATM交换机设计

本文提出一种宽带交换的新设计思想,它以异步传送模式为前提,能够保证各种宽带和窄带业务的综合交换。     

Broadband to the home (BTTH): architectures, access methods, andthe appetite for it

The demand for high-volume data transfer to the home for interactive multipurpose residential multimedia applications (such as tele-education, interactive on-demand entertainment, home shopping, browsing the World Wide Web to retrieve up-to-date information) and telecollaboration, including telecommuting to work, are continuously increasing. Technological advances and the 1996 Telecommunications (Deregulation) Act allow both telephone and television service providers to compete in each other's territory for providing broadband services to the home (BTTH). BTTH refers to broadband data services which may or may not use a high bandwidth link. It essentially gives the end user an impression or feeling that megabit-rate data transmission is occurring to/from the terminal, so the benefits of broadband services are enjoyed at the most convenient time within the comforts of home. It can be achieved for example, by using twisted pair copper wire telephone line using various types of digital subscriber line (xDSL) modems installed at both ends of the line. Issues and challenges of BTTH are discussed, in addition to describing future position(s) of the traditional service providers     

Wirefree in Patmos

This paper describes the author's involvement in an effort aimed at providing broadband Internet connectivity to the island of Patmos, a small island in the southeast Aegean sea. Different approaches to deploying WiFi are explored for the purpose of providing the convenience of always-on networking to all the physical spaces people frequent, both indoor and outdoor, thus providing cheap ubiquitous broadband Internet connectivity in places that very often have no other way to get that kind of service.     

Broadband Photoresponse Enhancement of a High‐Performance t‐Se Microtube Photodetector by Plasmonic Metallic Nanoparticles

Broadband responsivity enhancement of single Se microtube (Se‐MT) photodetectors in the UV–visible region is presented in this research. The pristine Se‐MT photodetector demonstrates broadband photoresponse from 300 to 700 nm with peak responsivity of ≈19 mA W^?1 at 610 nm and fast speed (rise time 0.32 ms and fall time 23.02 ms). To further enhance the responsivity of the single Se‐MT photodetector, Au and Pt nanoparticles (NPs) are sputtered on these devices. In contrast to only enhancement of responsivity in UV region by Pt NPs, broadband responsivity enhancement (≈600% to ≈800%) of the Se‐MT photodetector is realized from 300 to 700 nm by tuning the size and density of Au NPs. The broadband responsivity enhancement phenomena are interpreted by both the surface modification and surface plasmon coupling. The experimental results of this work provide an additional opportunity for fabricating high‐performance UV–visible broadband photodetectors.     

Technologies towards broadband ISDN

It is argued that it is vital to form a sound strategy for developing broadband integrated services digital network (BISDN) technology and services and deploying them in the field, so that smooth migration from the existing network is accelerated. Three major steps in this context are to expand fiber networks into the subscriber loop area to provide broadband capabilities everywhere, to construct a universal digital network that facilitates smooth evolution from the existing network to the broadband network of the future through deployment of (SDH) synchronous digital hierarchy transmission systems, and to integrate both services and network components through introduction of asynchronous transfer mode (ATM) technologies. Development efforts now being carried out at Fujitsu and Fujitsu Laboratories along this line are described, and the impact on network construction and service offerings is indicated     

A broad-band printed circuit hybrid ring power divider

The design of a broadband ring power divider that provides substantial improvement in coupling and phase characteristics over a wide frequency range compared to that of a conventional hybrid ring is presented. It is shown that the new power divider design can be easily constructed using realizable impedances and is applicable to both equal and unequal power divisions. Experimental verification of the broadband power divider was achieved in a stripline configuration at Ku-band for an equal power divider and a 3-dB power divider. Close agreement was observed between theoretical and experimental results for both of the power dividers. The usable bandwidth of the broadband power divider is approximately 45%. It is concluded that this broadband power divider is particularly suited for a narrowband low-sidelobe antenna array beam-forming network, for it provides substantially improved amplitude and phase characteristics, a requirement for low-sidelobe array antennas, and good isolation between output ports