WIRELESS COMMUNICATIONSWIRELESS COMMUNICATIONS
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`AND NETWORKSAND NETWORKS
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`SeCOND EDITIONSeCOND EDITION
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`
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`Williant StallingsWilliant Stallings
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`•Upper Saddle River, NJ 07458•Upper Saddle River, NJ 07458
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`Page 1 of 3
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`LG Electronics Exhibit 1012
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`Library of Congress Cataloging-in-Publication Data on file
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`Vice President and Editorial Director, ECS:
`MarciaJ Horton
`Publisher: Alan Apt
`Associate Editor: TOni D. Holm
`Editorial Assistant: Patrick Lindner
`Vice President and Director of Production and
`Manufacturing, ESM: David W Riccardi
`Executive Managing Editor: Vince OJBrien
`Managing Editor: Camille Trentacoste
`Production Editor: Rose Kernan
`Cover Photo: Brand X Pictures
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`Director of Creative Services: Paul Belfanti
`Art Director: Heather Scott
`Cover Designer: Tamara Newnam
`Managing Editor,AV Management
`and Production: Patricia Burns
`Art Editor: Gregory Dulles
`Manufacturing Manager: Trudy Pisdotti
`Manufacturing Buyer: Lynda Castillo
`Marketing Manager: Pamela Hersperger
`Marketing Assistant: Barrie Reinhold
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`• •
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`© 2005,2002 Pearson Education, Inc.
`Pearson Prentice Hall
`Pearson Education, Inc.
`Upper Saddle River, NJ 07458
`
`All rights reserved. No part of this book may be reproduced, in any form or by any means, without permission
`in writing from the publisher.
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`Pearson Prentice Hall® is a trademark of Pearson Education, Inc.
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`The author and publisher of this book have used their best efforts in preparing this book. These efforts include the
`development, research, and testing of the theories and programs to determine their effectiveness. The author and
`publisher make no warranty of any kind, expressed or implied, with regard to these programs or the documentation
`contained in this book. The author and publisher shall not be liable in any event for incidental or consequential
`damages in connection with, or arising out of, the furnishing, performance, or use of these programs.
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`Printed in the United States ofAmerica
`10987654321
`
`ISBN: 0-13-191835-4
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`Pearson Education Ltd., London
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`Pearson Education Singapore, Pte. Ltd.
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`Pearson Education Inc., Upper Saddle River, NewJersey
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`Page 2 of 3
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`10.1 / PRINCIPLES OF CELLULAR NETWORKS 277
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`3. In spread spectrum (SS) systems using code division multiple access (CDMA), it
`is desirable to equalize the received power level from all mobile units at the BS.
`This is crucial to system performance because all users have the same frequency
`allocation.
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`Cellular systems use the two kinds of power control. Open-loop power
`control depends solely on the mobile unit, with no feedback from the BS, and is
`used in some SS systems. In SS systems, the BS continuously transmits an unmod(cid:173)
`ulated signal, known as a pilot. The pilot allows a mobile unit to acquire the tim(cid:173)
`ing of the forward (BS to mobile) CDMA channel and provides a phase
`reference for demodulation. It can also be used for power control. The mobile
`unit monitors the received power level of the pilot and sets the transmitted
`power in the reverse (mobile to BS) channel inversely proportional to it. This
`approach assumes that the forward and reverse link signal strengths are closely
`correlated, which is generally the case. The open-loop approach is not as accurate
`as the closed-loop approach. However, the open-loop scheme can react more
`quickly to rapid fluctuations in signal strength, such as when a mobile unit
`emerges from behind a large building. This fast action is required in the reverse
`link of a CDMA system where the sudden increase in received strength at the BS
`may suppress all other signals.
`Closed-loop power control adjusts signal strength in the reverse (mobile to
`BS) channel based on some metric of performance in that reverse channel, such as
`received signal power level, received signal-to-noise ratio, or received bit error
`rate. The BS makes the power adjustment decision and communicates a power
`adjustment command to the mobile unit on a control channel. Closed-loop power
`control is also used to adjust power in the forward channel. In this case, the mobile
`unit provides information about received signal quality to the BS, which then
`adjusts transmitted power.
`Table 10.2 shows the power classes used in the GSM standard, which is a
`TDMA standard and is discussed in Section 10.3. GSM defines eight classes of base
`station channels and five classes of mobile stations, according to their power output.
`Adjustments in both directions are made using closed-loop power control.
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`Mobile Station Power
`(watts)
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`20
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`8 5
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`Table 10.2 GSM Transmitter Classes
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`Power. Class
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`Page 3 of 3