We discussed wireless LANs in chapter 14. Wireless technology is also used in cellular telephony and satellite networks. We discuss the former in this chapter as well as examples of channelization access methods (see Chapter 12). We also briefly discuss satellite networks, a technology that eventually will be linked to cellular telephony to access the Internet directly.
GSM (Global System for Mobile Communications), is a standard set developed by the European Telecommunications Standards Institute (ETSI) to describe technologies for second generation digital cellular networks. Developed as a replacement for first generation analog cellular networks, the GSM standard originally described a digital, circuit switched network optimized for full duplex voice telephony. The standard was expanded over time to include first circuit switched data transport, then packet data transport via GPRS (General Packet Radio Services)....
Generation Change in Cellular Systems
In Japan, mobile communications systems based on cellular technology have evolved, as illustrated in Figure 1.1. The ﬁrst-generation analog car phones were ﬁrst introduced in 1979, followed by the commercialization of the second-generation digital phones in 1993. Mobile phone subscribers have rapidly increased in number since then, owing to the liberation of terminal sales and continuous price reductions. In March 2000, the number of mobile phone subscribers outnumbered those of ﬁxed telephones.
Radio Transmission Systems
2.1 Direct Sequence Code Division Multiple Access (DS-CDMA)
2.1.1 Principles of DS-CDMA DS-CDMA is a radio-access technology that enables multiple access based on a spread spectrum system. Figure 2.1a shows how DS-CDMA works [1–3]. The transmitted data sequence is spread across the spectrum after being encoded by spreading codes, each of which is assigned uniquely to each user at a higher rate than the symbol rate of the information data.
As stated in Chapter 1, Section 1.2, requirements for International Mobile Telecommunications-2000 (IMT-2000) include system ﬂexibility, economy and conditions on data transmission speed deﬁned in numerical terms. The minimum performance requirement in terms of transmission speed is 2 Mbit/s in an indoor environment, 384 kbit/s in a pedestrian mode and 144 kbit/s in a vehicle mode.
The Introduction of International Mobile Telecommunications-2000 (IMT-2000) has enabled high-speed data transmission, laying the groundwork for full-scale multimedia communications in mobile environments. Taking into account the characteristics and limitations of radio access, multimedia processing suitable for mobile communication is required. In this chapter, signal processing, which is a basic technology for implementing multimedia communication, is ﬁrst discussed.
The Digivance Indoor Coverage Solution (ICS) is used to extend coverage to specific areas
within a building, multiple buildings, or throughout a campus environment. This digital
distributed antenna system (D-DAS) solution features unique, patented technology that
distributes wireless coverage digitally over optical fiber, making Digivance ICS the best
choice for signal quality, flexibility, and overall performance. Its digitized optical RF transport
also future-proofs in-building wireless infrastructure for higher data rate services.
The Information Technology Laboratory (ITL) at the National Institute of Standards and Technology (NIST) promotes the U.S. economy and public welfare by providing technical leadership for the Nation’s
measurement and standards infrastructure. ITL develops tests, test methods, reference data, proof of concept implementations, and technical analyses to advance the development and productive use of
This text provides the student and professional mechanical engineer with a reference text of an essentially practical nature. It is uncluttered by text, and extensive use of illustrations and tables provide quick and clear access to information. It also includes examples of detailed calculations on many of the applications of technology used by mechanical and production engineers, draughtsmen and engineering designers.
No part of this publication may be reproduced in any material form (includmg photocopying or storing in any medium by electronic means and whether or not transiently or incidentally to some other use of this publication) without the written permission of the copyright holder except in accordance with the provisions of the Copyright, Designs and Patents Act 1988 or under the terms of a licence issued by
Highly experienced physicians and biologists clearly explain the basic technical knowledge needed to use AFM and demonstrate its multifarious uses in biomedicine and the life sciences. The applications range widely from morphostructural analyses of cellular structures, to the investigation of subcellular structures, to functional investigations, and reveal a powerful new way of looking at biological samples.
An access point (AP) provides the connection between one or
more wireless client devices and a wired local area network
(LAN). The AP is usually connected to the LAN via a
Category-5 cable connection to a hub or switch. Client
devices communicate with the AP over the wireless link, giving
them access to all other devices through the hub or
switch, including a router on the other side of the hub, which
provides Internet access
Ultra wideband (UWB) has advanced and merged as a technology, and many more people are aware of the potential for this exciting technology. The current UWB field is changing rapidly with new techniques and ideas where several issues are involved in developing the systems. Among UWB system design, the UWB RF transceiver and UWB antenna are the key components. Recently, a considerable amount of researches has been devoted to the development of the UWB RF transceiver and antenna for its enabling high data transmission rates and low power consumption.
Several figures in this primer show the cumulative percent change in private health
insurance or health insurance premiums (Figures 11, 15, and 20). These cumulative
increases may vary from figure to figure because different years are used, the data
sources differ, and what is being measured varies.
In recent years, wireless and mobile communications have seen explosive growth both in terms of the number of services provided and the types of technologies that have become available. Indeed, cellular telephony, radio paging, cellular data, and even rudimentary multimedia services have become commonplace and the demand for enhanced capabilities will continue to grow into the foreseeable future [6, 12, 43, 46].
All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording, or otherwise, without the prior written permission of the publisher. This book is printed on acid-free paper. Library of Congress Cataloging-in-Publication Data Lai, W.
There has been some concern that the use of the endocervical brush can result in the
appearance of a much greater number of endocervical cells in a smear and that their
arrangement in large sheets might mimic malignancy. To avoid this problem clinicians should
inform the laboratory when an endocervical brush is used for collecting the smear.