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GSM Networks: Protocols, Terminology and Implementation
GSM Networks: Protocols, Terminology, and Implementation GSM Networks: Protocols, Terminology, and Implementation Gunnar Heine Artech House Boston • London Library of Congress Cataloging-in-Publication Data Heine, Gunnar [GSM—Signalisierung verstehen und praktisch anwenden English] GSM networks : protocols, terminology, and implementation / Gunnar Heine p cm — (Artech House mobile communications library) Translation of: GSM—Signalisierung verstehen und praktisch anwenden Includes bibliographical references and index ISBN 0-89006-471-7 (alk paper) Global system for mobile communications I Title TK5103.483.H4513 1998 621.3845’6—dc21 98-51784 CIP British Library Cataloguing in Publication Data Heine, Gunnar GSM networks : protocols, terminology, and implementation— (Artech House mobile communications library) Global system for mobile communications I Title 621.3’8456 ISBN 0-89006-471-7 Cover design by Lynda Fishbourne © 1998 Franzis’ Verlag GmbH Translated from GSM - Signalisierung verstehen und praktisch anwenden (Franzis’ Verlag 1998) English translation version: © 1999 ARTECH HOUSE, INC 685 Canton Street 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: 0-89006-471-7 Library of Congress Catalog Card Number: 98-51784 10 Contents 1.1 1.2 1.2.1 1.2.2 1.3 1.4 1.4.1 1.4.2 1.4.3 1.5 2.1 2.1.1 2.1.2 2.2 2.2.1 Introduction About This Book Global System for Mobile Communication (GSM) The System Architecture of GSM: A Network of Cells An Overview on the GSM Subsystems The Focus of This Book Signaling What is Signaling? How is Signaling Performed? What is Signaling Used For? 10 Representation of Messages 10 The Mobile Station and the Subscriber Identity Module 13 Subscriber Identity Module 13 The SIM as a Database 15 Advantage for the Subscriber 15 Mobile Station 17 Types of Mobile Stations 17 v vi GSM Networks: Protocols, Terminology, and Implementation 2.2.2 2.2.3 Functionality 17 Mobile Stations as Test Equipment 18 The Base Station Subsystem 19 3.1 3.1.1 Base Transceiver Station 19 3.1.2 3.2 3.2.1 Base Transceiver Station Configurations 22 Base Station Controller 25 Architecture and Tasks of the Base Station Controller 26 Transcoding Rate and Adaptation Unit 28 Function of the Transcoding Rate and Adaptation Unit 28 Site Selection for Transcoding Rate and Adaptation Unit 28 Relationship Between the Transcoding Rate, Adaptation Unit, and Base Station Subsystem 29 The Network Switching Subsystem 31 Home Location Register and Authentication Center 32 Visitor Location Register 33 The Mobile-Services Switching Center 34 Gateway MSC 36 The Relationship Between MSC and VLR 36 Equipment Identity Register 37 The OSI Reference Model 39 Reasons for Standardization 39 Layering in the OSI Reference Model 40 Data Types of the OSI Reference Model 41 Information Processing in the OSI Reference Model 42 3.3 3.3.1 3.3.2 3.3.3 4.1 4.2 4.3 4.3.1 4.3.2 4.4 5.1 5.2 5.3 5.4 Architecture and Functionality of a Base Transceiver Station 20 Contents 5.5 5.6 5.6.1 5.6.2 5.6.3 5.6.4 5.6.5 5.6.6 5.6.7 5.7 5.7.1 6.1 6.2 6.2.1 6.2.2 6.3 6.3.1 6.3.2 6.3.3 6.4 6.4.1 6.4.2 7.1 7.1.1 7.1.2 7.1.3 7.2 7.3 vii Advantages of the OSI Reference Model 42 The Seven Layers of the OSI Reference Model 43 Layer 1: The Physical Layer 43 Layer 2: The Data Link Layer 43 Layer 3: The Network Layer 44 Layer 4: The Transport Layer 44 Layer 5: The Session Layer 45 Layer 6: The Presentation Layer 45 Layer 7: The Application Layer 46 Comprehension Issues 46 An Analogy: The Move to Europe 47 The Abis-Interface 51 Channel Configurations 51 Alternatives for Connecting the BTS to the BSC 52 BTS Connection in a Serial Configuration 54 Connection of BTSs in Star Configuration 55 Signaling on the Abis-Interface 55 OSI Protocol Stack on the Abis-Interface 55 Layer 56 Layer 71 Bringing an Abis-Interface Into Service 87 Layer 87 Layer 87 The Air-Interface of GSM 89 The Structure of the Air-Interface in GSM 89 The FDMA/TDMA Scheme 89 Frame Hierarchy and Frame Numbers 90 Synchronization Between Uplink and Downlink 93 Physical Versus Logical Channels 94 Logical-Channel Configuration 94 viii GSM Networks: Protocols, Terminology, and Implementation 7.3.1 7.3.2 7.4 7.5 7.5.1 7.5.2 Mapping of Logical Channels Onto Physical Channels 95 Possible Combinations 97 Interleaving 100 Signaling on the Air Interface 101 Layer LAPDm Signaling 101 Layer 107 Signaling System Number 125 8.1 8.2 8.3 8.3.1 8.3.2 8.3.3 8.4 8.4.1 The SS7 Network 125 Message Transfer Part 126 Message Types in SS7 127 Fill-In Signal Unit 127 Link Status Signal Unit 128 Message Signal Unit 128 Addressing and Routing of Messages 130 8.4.2 8.5 8.5.1 Example: Commissioning of an SS7 Connection 132 Error Detection and Error Correction 133 Send Sequence Numbers and Receive Sequence Numbers (FSN, BSN, BIB, FIB) 135 BSN/BIB and FSN/FIB for Message Transfer 135 SS7 Network Management and Network Test 138 SS7 Network Test 139 Possible Error Cases 140 Format of SS7 Management Messages and Test Messages 142 Messages in SS7 Network Management and Network Test 142 Signaling Connection Control Part 153 Tasks of the SCCP 153 8.5.2 8.6 8.6.1 8.6.2 8.6.3 8.6.4 9.1 Example: Determination of DPC, OPC, and SLS in a Hexadecimal Trace 131 Contents 9.1.1 9.1.2 9.2 9.3 9.3.1 9.3.2 9.3.3 9.4 10 10.1 10.2 10.2.1 10.2.2 10.2.3 10.2.4 11 11.1 11.1.1 11.1.2 11.1.3 11.1.4 11.2 11.2.1 11.2.2 11.2.3 ix Services of the SCCP: Connection-Oriented Versus Connectionless 154 Connection-Oriented Versus Connectionless Service 154 The SCCP Message Format 156 The SCCP Messages 158 Tasks of the SCCP Messages 158 Parameters of SCCP Messages 159 Decoding a SCCP Message 167 The Principle of a SCCP Connection 167 The A-Interface 171 Dimensioning 171 Signaling Over the A-Interface 173 The Base Station Subsystem Application Part 173 The Message Structure of the BSSAP 174 Message Types of the Base Station Subsystem Management Application Part 176 Decoding of a BSSMAP Message 183 Transaction Capabilities and Mobile Application Part 185 Transaction Capabilities Application Part 185 Addressing in TCAP 186 The Internal Structure of TCAP 187 Coding of Parameters and Data in TCAP 189 TCAP Messages Used in GSM 198 Mobile Application Part 208 Communication Between MAP and its Users 209 MAP Services 211 Local Operation Codes of the Mobile Application Part 214 x GSM Networks: Protocols, Terminology, and Implementation 11.2.4 12 12.1 12.1.1 12.1.2 12.2 12.3 12.3.1 12.3.2 12.4 12.4.1 12.4.2 12.5 12.5.1 12.5.2 12.5.3 13 13.1 13.1.1 13.1.2 13.2 13.2.1 13.2.2 13.3 13.3.1 13.4 13.5 13.5.1 Communication Between Application, MAP, and TCAP 220 Scenarios 225 Location Update 227 Location Update in the BSS 227 Location Update in the NSS 227 Equipment Check 227 Mobile Originating Call 233 Mobile Originating Call in the BSS 233 Mobile Originating Call in the NSS 233 Mobile Terminating Call 244 Mobile Terminating Call in the BSS 244 Mobile Terminating Call in the NSS 244 Handover 251 Measurement Results of BTS and MS 251 Analysis of a MEAS_RES/MEAS_REP 255 Handover Scenarios 256 Quality of Service 275 Tools for Protocol Measurements 275 OMC Versus Protocol Analyzers 276 Protocol Analyzer 278 Signaling Analysis in GSM 280 Automatic Analysis of Protocol Traces 280 Manual Analysis of Protocol Traces 284 Tips and Tricks 285 Identification of a Single Connection 285 Where in the Trace File to Find What Parameter? 287 Detailed Analysis of Errors on Abis Interface and A-Interface 287 Most Important Error Messages 291 Contents 13.5.2 xi Error Analysis in the BSS 296 Glossary 303 About the Author 405 Index 407 ... contain references to GSM and International Telecommunication Union (ITU) Recommendations, which in turn allow for further research GSM Networks: Protocols, Terminology, and Implementation For the... system and when? How is such an indication interpreted? What are the potential sources of errors? GSM Networks: Protocols, Terminology, and Implementation A word on coding of parameters and messages... via an interface called the Abis-interface The GSM Networks: Protocols, Terminology, and Implementation BSC takes care of all the central functions and the control of the subsystem, referred to