Fiber-Optic Sensing: A Historical Perspective

Sensing via fiber optics has occupied R&D groups for over 40 years, and some important transitions into the commercial sector have been achieved. We look at the fundamental concepts involved in the various sensing approaches, and the differentiators which have led to commercial impact. We also look to the future of fiber-optic sensors.     

Design and Development of Dipole Array Antenna for Wi-Fi Applications

Wireless Personal Communications - This paper illustrates the design and development of the series-fed two-dipole-array antenna (STDA) for Wi-Fi applications. The proposed antenna consists of two...     

Communication Technology: A Societal Perspective

Historically the communications industry has been dominated by technology. Concepts such as efficiency, size, and fidelity have been the controlling factors affecting product and system design. Now, however, a wide variety of devices and systems can be provided to the consumer of communication services, assuming limited development of the relevant technologies. This requires that choices be made about what is worthwhile pursuing. Since these decisions will shape communication systems for years to come, inputs to the choice process ought to reflect considerations other than just short-run economics and technological feasibility. In particular, these choices ought to reflect societal needs. To assist in evaluating the impact of alternative communication systems on society, we propose three dimensions along which “social” values might be measured. These are: 1) ease of access to stored information, 2) scope of the interaction space common to the communicants, 3) the extent to which provisions exist to take feedback into consideration. The meaning and measurement of each dimension is explored, and a suggestion is made on how they might be applied. An example of a proposed communication system is presented that would appear to have high values along each of the three dimensions.     

Microwave Instrumentation: An Historical Perspective

Metrology is the science of measurements. When one is making a measurement, one is comparing an unknown quantity of some measure with a known (calibrated) quantity of the same measure. The equipment being used in electronics, especially in microwaves, is called instrumentation. When making measurements, using the appropriate instrumentation, the basic rules of metrology have to be observed. It is not enough to gather the data by performing the test; an evaluation of the errors involved also has to be determined. Resolution, readability, repeatability, and absolute calibration accuracy are all important factors in these considerations. It was exactly the evolution of these factors (the need for better accuracy and more data points by systems engineers) which fueled this process. When the measurement techniques fulfilled the requirements of systems designers, better, more sophisticated systems were possible to invent, which in turn posed the need for more improvements in instrumentation.     

Issue Evolution: A New Perspective on Presidential Debates

Issues may endure from campaign to campaign but their relation to the substantive areas of controversy may vary.     

Wi-Fi新技术研究与展望

以最新的几款符合draft 802.11n草案标准的Wi-Fi产品为例,详细分析了其关键技术和各自的设计特点.随后通过性能测试对比,指出Wi-Fi新设备存在的问题,对Wi-Fi设备的发展进行了总结与展望.     

宽带无线接入技术WiMAX及其与Wi-Fi对比

本文介绍了下一代宽带无线接入技术WiMAX的技术特点,并将WiMAX技术与Wi-Fi进行了对比,最后叙述了WiMAX发展面临的问题.     

Wi-Fi与移动电话:融合势在必行

随着中国中产阶层的壮大和人民富裕程度的提高,在家庭和工作中使用电脑的人数在日益增多,这个数字还在继续高速增长.而且中国的宽带用户数也是空前的.无线局域网(Wi-Fi)的移动性和便利性正在为中国的消费者所接受.同世界其它地区一样,计算机的应用和宽带网接入正在推动中国无线局域网需求的增长.同时,中国消费者已经欣然接受了手机,中国目前是全球最大的手机市场,有大约3.8亿手机用户,预计到2010年将达到7亿(易观国际2006年预测).消费者需要手机厂商和移动运营商提供技术创新产品和不断地改善服务.     

Evolution of WDM Optical IP Networks: A Cost and Energy Perspective

We review technologies and architectures for WDM optical IP networks from the viewpoint of capital expenditure and network energy consumption. We show how requirements of low cost and low energy consumption can influence the choice of switching technologies as well as the overall network architecture.      

Standardization of Propagation Models for Terrestrial Cellular Systems: A Historical Perspective

Propagation models constitute a fundamental building block of wireless communications research. Before we build and operate real systems, we must understand the science of radio propagation, and develop channel models that both reflect the important propagation processes and allow a fair comparison of different systems. In the past five decades, wireless systems have gone through five generations, from supporting voice applications to enhanced mobile broadband. To meet the ever increasing data rate demands of wireless systems, frequency bands covering a wide range from 800 MHz to 100 GHz have been allocated for use. The standardization of these systems started in the early/mid 1980s in Europe by the European Telecommunications Standards Institute with the advent of Global System for Mobile Communications. This motivated the development of the first standardized propagation model by the European Cooperation in Science and Technology (COST) 207 working group. These standardization activities were continued and expanded for the third, fourth, and fifth generations of COST, as well as by the Third Generation Partnership Project, and the International Telecommnunication Union. This paper presents a historical overview of the standardized propagation models covering first to fifth-generation systems. In particular, we discuss the evolution and standardization of pathloss models, as well as large and small-scale fading parameters for single antenna and multiple antenna systems. Furthermore, we present insights into the progress of deterministic modelling across the five generations of systems, as well as discuss more advanced modelling components needed for the detailed simulations of millimeter-wave channels. A comprehensive bibliography at the end of the paper will aid the interested reader to dig deeper.

     

A Review of WDM Technology and Applications

The rapid growth in demand for high-capacity telecommunication links, and the speed limitation of single-wavelength links, has resulted in an extraordinary increase in the use of wavelength-division multiplexing (WDM) in advanced lightwave networks. In this work we review the basic concepts of WDM, describe its key features and why network providers are using it, review the enabling technologies, discuss the basic operating characteristics and their associated parameters, and show how WDM is being used worldwide in both terrestrial and undersea installations. Included in this are discussions on management functions that are needed for monitoring the status and health of WDM networks.     

IoT Technology,Applications and Challenges: A Contemporary Survey

Wireless Personal Communications - Internet of things (IoT) is a very unique platform which is getting very popular day by day. The very reason for this to happen is the advancement in technology...     

5G技术演进对通信基础设施的影响及解决建议

深入分析和探究5G(第五代移动通信)网络技术,提出5G技术在演进过程中将面临的诸如站点获取、基站机房和天面、电源获取、承载网络等挑战。针对这些挑战深入分析,探究其产生的原因,提出应对挑战的方案建议。例如,针对站点获取的挑战提出应该遵循"宏微协同,异频组网"的原则;针对基站机房和天面的挑战提出"点亮"小基站与超密集组网的建议;针对电源获取的挑战提出"智能化能耗调节,动态休眠"的建议。     

对网络演进相关问题的思考

最近两年,世界主流电信运营商陆续发布了自身网络的演进战略。其核心都是基于SDN、NFV和云化数据中心等IT技术构建的新一代电信网络基础设施。在这些新技术的部署过程中,文章分析各种IT技术运用到电信网络存在的局限性,概括电信网络演进中的IT化趋势,提出网络演进应当优化使用各种IT技术,更加注重网络的自动化运维。     

TRILOGUE系统的技术与应用

本文简要叙述Ｃｏｍｖｅｒｓｅ技术公司ＴＲＩＬＯＧＵＥ系统提供的增值业务技术及功能，主要有话音信箱、改号通知、信息服务、传真邮件、呼叫卡、远程接入及计费等。     

Quad Band Printed Antenna for Wi-Fi,WLAN, C-band and WiMAX Applications

Wireless Personal Communications - Software Defined Networks (SDNs) is an emerging concept in network architectures, which divides the network operations into two, control and data, layers. In this...     

Monolithic Microwave Integrated Circuits: An Historical Perspective

Monolithic microwave integrated-circuit (MMIC) technology as it exists today has evolved from events that occurred during the middle-to-late 1950's and early 1960's. These events are reconstructed through a review of the published literature, government contract reports and proposals, U.S. patents, and private communications with individuals directly involved in early MMIC development. No single point in time can be viewed as that historical moment when the idea of an MMIC was formalized; rather, the idea evolved over a period of time as a direct result of the successful development of analog and digital IC's and the push by the military services (primarily the Air Force at Wright Patterson) to apply semiconductor technology in defense systems, the evolutionary period is presented in chronological order and includes a discussion of the role played by the Molecular Electronics for Radar Applications program. Early development activities were pursued, with both silicon and GaAs used as the monolithic material. These activities, the early problems encountered with both materials, and the influence the problems had in molding today's technology are described.