文档介绍：Voice over
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Voice over
Frank Ohrtman
Artech House
Boston • London
Library of Congress Cataloging-in-Publication Data
Ohrtman, Frank.
Voice over Ohrtman.
p. cm.
Includes bibliographical references and index.
ISBN 1-58053-677-8 (alk. paper)
1. IEEE (Standard) 2. telephony. I. Title.
2004
’12—dc22 2004041074
British Library Cataloguing in Publication Data
Ohrtman, Frank
Voice over .—(Artech House munications library)
1. telephony 2. munication systems 3. munications
systems 4. IEEE (Standard)
I. Title
’845
ISBN 1-58053-677-8
Cover design by Gary Ragaglia
© 2004 ARTECH HOUSE, INC.
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Norwood, MA 02062
All rights reserved. Printed and bound in the United States of America. No part of this book
may be reproduced or utilized in any form or by any means, electronic or mechanical, including
photocopying, recording, or by any information storage and retrieval system, without permission
in writing from the publisher.
All terms mentioned in this book that are known to be trademarks or service marks have been
appropriately capitalized. Artech House cannot attest to the accuracy of this information. Use of
a term in this book should not be regarded as affecting the validity of any trademark or service
mark.
International Standard Book Number: 1-58053-677-8
**********
To Michelle Otte
Contents
1 Overview of 1
Access 1
Switching 2
Transport 2
: Bypassing the Local Loop 3
Reference 4
2 : Alternative Access 5
How Does WiFi Work? 5
How Data Is Transmitted Via Wireless Technology 6
The Significance of Spread Spectrum Radio 8
Variants 8
FHSS () 9
DSSS 11
Orthogonal Frequency-Division Multiplexing 11
Carrier Multiplexing 13
MAC Concepts and Architecture 13
MAC Layer Ser