The dictionary definition of telecommunications is ‘communication over long distance by cable, telegraph, telephone or broadcasting’, but since its initiation over 100yearsagothingshavemovedrapidly.Telecommunicationsisnowaverycomplex industrywithmanydifferentpressures,operatinginahighlydynamic environment.It is best viewed as part of a wider industry known as information and communication technology (ICT). The purpose of this chapter is to explain where telecommunication fits in, to highlight some of the complexities – hopefully to simplify them – and to position the industry in today’s dynamic business environment.
标签： Telecommunications Understanding Business
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Once upon a time, cellular wireless networks provided two basic services: voice telephony and low-rate text messaging. Users in the network were separated by orthogonal multiple access schemes, and cells by generous frequency reuse patterns [1]. Since then, the proliferation of wireless services, fierce competition, andthe emergenceof new service classes such as wireless data and multimediahave resulted in an ever increasing pressure on network operators to use resources in a moreefficient manner.In the contextof wireless networks,two of the most common resources are power and spectrum—and, due to regulations, these resources are typically scarce. Hence, in contrast to wired networks, overprovisioning is not feasible in wireless networks.
标签： Maximization Nonconvex Wireless Utility Systems in
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n the first part of this book, we give an introduction to the basic applications of wireless com- munications, as well as the technical problems inherent in this communication paradigm. After a brief history of wireless, Chapter 1 describes the different types of wireless services, and works out their fundamental differences. The subsequent Section 1.3 looks at the same problem from a different angle: what data rates, ranges, etc., occur in practical systems, and especially, what combination of performance measures are demanded (e.g., what data rates need to be transmitted over short distances; what data rates are required over long distances?) Chapter 2 then describes the technical challenges of communicating without wires, putting special emphasis on fading and co-channel interference. Chapter 3 describes the most elementary problem of designing a wireless system, namely to set up a link budget in either a noise-limited or an interference-limited system. After studying this part of the book, the reader should have an overview of different types of wireless services, and understand the technical challenges involved in each of them. The solutions to those challenges are described in the later parts of this book.
标签： Communications Wireless Edition 2nd
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During the past three decades, the world has seen signifi cant changes in the telecom- munications industry. There has been rapid growth in wireless communications, as seen by large expansion in mobile systems. Wireless communications have moved from fi rst-generation (1G) systems primarily focused on voice communications to third-generation (3G) systems dealing with Internet connectivity and multi-media applications. The fourth-generation (4G) systems will be designed to connect wire- less personal area networks (WPANs), wireless local area networks (WLANs) and wireless wide-area networks (WWANs).
标签： Communications Networking Wireless
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Mobile radio communications are evolving from pure telephony systems to multimedia platforms offering a variety of services ranging from simple file transfers and audio and video streaming, to interactive applications and positioning tasks. Naturally, these services have different constraints concerning data rate, delay, and reliability (quality-of-service (QoS)). Hence, future mobile radio systems have to provide a large flexibility and scal- ability to match these heterogeneous requirements.
标签： Communications Wireless Channels MIMO over
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The explosion in demand for wireless services experienced over the past 20 years has put significant pressure on system designers to increase the capacity of the systems being deployed. While the spectral resource is very scarce and practically exhausted, the biggest possibilities are predicted to be in the areas of spectral reuse by unlicensed users or in exploiting the spatial dimension of the wireless channels. The former approach is now under intense development and is known as the cogni- tive radio approach (Haykin 2005).
标签： Multi-Antenna Wireless Channels Modeling
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Electrostatic discharge (ESD) events can have serious detrimental effects on the manufacture and performance of microelectronic devices, the systems that contain them, and the manufacturing facilities used to produce them. Submicron device technologies, high system operating speeds, and factory automation are making ESD control programs a critical factor in the quality and reliability of ESD-sensitive products.
标签： Management Program ESD
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This text, ESD Basics: From Semiconductor Manufacturing to Product Use was initiated on the need to produce a text that addresses fundamentals of electrostatic discharge from the manufacturing environment to today’s products. As the manufacturing world evolves, semi- conductor networks scale, and systems are changing, the needs and requirements for reliabi- lity and ESD protection are changing. A text is required that connects basic ESD phenomena to today’s real world environment.
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Applications of microelectromechanical systems (MEMS) and microfabrica- tion have spread to different fields of engineering and science in recent years. Perhaps the most exciting development in the application of MEMS technol- ogy has occurred in the biological and biomedical areas. In addition to key fluidic components, such as microvalves, pumps, and all kinds of novel sensors that can be used for biological and biomedical analysis and mea- surements, many other types of so-called micro total analysis systems (TAS) have been developed.
标签： Applications Technologies Bio-MEMS and
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The planarization technology of Chemical-Mechanical-Polishing (CMP), used for the manufacturing of multi- level metal interconnects for high-density Integrated Circuits (IC), is also readily adaptable as an enabling technology in MicroElectroMechanical Systems (MEMS) fabrication, particularly polysilicon surface micromachining. CMP not only eases the design and manufacturability of MEMS devices by eliminating several photolithographic and film issues generated by severe topography, but also enables far greater flexibility with process complexity and associated designs. T
标签： mechanical polishing Chemical
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