Introduction to GPRS - Motorola Training

CHAPTER 2 CHAPTER 3 CHAPTER 4 CHAPTER 5CHAPTER 1

Cellular Infrastructure Group

CP07INTRODUCTION TO GPRS

FOR TRAINING PURPOSES ONLY

ISSUE 1 REVISION 3

FOR TRAININGPURPOSES ONLY

ISSUE 1REVISION 3

CP07INTRODUCTION TO

GPRS

CP07INTRODUCTION TO GPRS

�MOTOROLA LTD. 2001 CP07: Introduction to GPRS


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ISSUE 1 REVISION 3

CP07Introduction to GPRS

� Motorola 1993, 1994, 1995, 1996, 1997, 1998, 1999All Rights ReservedPrinted in the U.K.

ISSUE 1 REVISION 3

�MOTOROLA LTD. 2001CP07: Introduction to GPRS


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Copyrights, notices and trademarks

CopyrightsThe Motorola products described in this document may include copyrighted Motorola computerprograms stored in semiconductor memories or other media. Laws in the United States and othercountries preserve for Motorola certain exclusive rights for copyright computer programs, including theexclusive right to copy or reproduce in any form the copyright computer program. Accordingly, anycopyright Motorola computer programs contained in the Motorola products described in this documentmay not be copied or reproduced in any manner without the express written permission of Motorola.Furthermore, the purchase of Motorola products shall not be deemed to grant either directly or byimplication, estoppel or otherwise, any license under the copyrights, patents or patent applications ofMotorola, except for the rights that arise by operation of law in the sale of a product.

RestrictionsThe software described in this document is the property of Motorola. It is furnished under a licenseagreement and may be used and/or disclosed only in accordance with the terms of the agreement.Software and documentation are copyright materials. Making unauthorized copies is prohibited bylaw. No part of the software or documentation may be reproduced, transmitted, transcribed, storedin a retrieval system, or translated into any language or computer language, in any form or by anymeans, without prior written permission of Motorola.

AccuracyWhile reasonable efforts have been made to assure the accuracy of this document, Motorolaassumes no liability resulting from any inaccuracies or omissions in this document, or from the useof the information obtained herein. Motorola reserves the right to make changes to any productsdescribed herein to improve reliability, function, or design, and reserves the right to revise thisdocument and to make changes from time to time in content hereof with no obligation to notify anyperson of revisions or changes. Motorola does not assume any liability arising out of the applicationor use of any product or circuit described herein; neither does it convey license under its patentrights of others.

Trademarks

and MOTOROLA are trademarks of Motorola Inc.UNIX is a registered trademark in the United States and other countries, licensed exclusively throughX/Open Company Limited.Tandem , Integrity , Integrity S2 , and Non-Stop-UX are trademarks of Tandem ComputersIncorporated.X Window System , X and X11 are trademarks of the Massachusetts Institute of Technology.Looking Glass is a registered trademark of Visix Software Ltd.OSF/Motif is a trademark of the Open Software Foundation.Ethernet is a trademark of the Xerox Corporation.Wingz is a trademark and INFORMIX is a registered trademark of Informix Software Ltd.SUN, SPARC, and SPARCStation are trademarks of Sun Microsystems Computer Corporation.IBM is a registered trademark of International Business Machines Corporation.HP is a registered trademark of Hewlett Packard Inc.

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General information 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Important notice 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Purpose 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . About this manual 1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cross references 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Text conventions 2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

First aid in case of electric shock 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Warning 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Artificial respiration 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Burns treatment 3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reporting safety issues 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Procedure 4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Warnings and cautions 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Warnings 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Cautions 5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General warnings 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Warning labels 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific warnings 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . High voltage 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . RF radiation 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Laser radiation 6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Lifting equipment 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Do not ... 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Battery supplies 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Toxic material 7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Human exposure to radio frequency energy (PCS1900 only) 8. . . . . . . . . . . . . . . . . . . . . . Introduction 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Definitions 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maximum permitted exposures 8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Maximum permitted exposure ceilings 9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Example calculation 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Power density measurements 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Other equipment 10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Beryllium health and safety precautions 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Health issues 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Inhalation 11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Skin contact 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Eye contact 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Handling procedures 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Disposal methods 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Product life cycle implications 12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

General cautions 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Caution labels 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Specific cautions 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fibre optics 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Static discharge 13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Devices sensitive to static 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Special handling techniques 14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Motorola GSM manual set 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Introduction 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Generic manuals 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Tandem OMC 15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Scaleable OMC 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Related manuals 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Service manuals 16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Category number 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Catalogue number 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ordering manuals 17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 1GSM Review i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Evolution of GSM 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 1 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 2 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 2+ 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Network Architecture 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Base Station System (BSS) 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mobile Station (MS) 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mobile Services Switching Centre (MSC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Home Location Register (HLR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Visitor Location Register (VLR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Equipment Identity Register (EIR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Authentication Centre (AUC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echo Canceller (EC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interworking Function (IWF) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Operations and Maintenance Centre Radio (OMC-R) 1–6. . . . . . . . . . . . . . . . . . . . . .

Interworking Function (IWF) 1–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Channel Combinations 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Timeslot Allocation 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GSM Channel Coding 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14.4 Kbps Data Rate 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Voice and Data through GSM 1–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data connection through GSM 1–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 2GPRS Outline i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Today’s use of Data 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Future Data Usage and Applications 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Industry Convergence 2–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Circuit and Packet Switching 2–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Circuit Switching 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Switching 2–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Datagrams and Virtual Circuits 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Datagrams 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Virtual Circuit 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Permanent Virtual Circuit (PVC) 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Symbian and Bluetooth 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Symbian 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bluetooth 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wireless Application Protocol 2–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS 2–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Infrastructure 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gateway GSN (GGSN) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Serving GPRS Support Node (SGSN) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Control Unit (PCU) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MSC, HLR and VLR 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS network elements 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gateway GPRS Support Node (GGSN) 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Serving GPRS Support Node (SGSN) 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Control Unit (PCU) 2–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Mobile Stations 2–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 3Terrestrial Interfaces i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the GGSN 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GPRS Tunnelling Protocol (GTP) 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . User Datagram Protocol (UDP) Header 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmission Control Protocol (TCP) Header 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internet Protocol (IP) 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the SGSN 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sub–network Dependent Convergence Protocol (SNDCP) 3–10. . . . . . . . . . . . . . . . . . . . . . . .

SNDCP Service Functions 3–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Logical Link Control (LLC) 3–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Base Station System GPRS Protocol (BSSGP) 3–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BSSGP Virtual Connection Identifier (BVCI) 3–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Frame Relay Operation 3–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 4Air Interface i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Logical Channels 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Broadcast Control Channel (PBCCH) 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Common Control Channel (PCCCH) 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Dedicated Control Channels 4–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Traffic Channels 4–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

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Allocation of Resources 4–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Release of PDCH 4–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Multiframe Structure for PDCH 4–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Downlink Resource Allocation 4–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Uplink Resource Allocation 4–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fixed Allocation 4–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dynamic Allocation 4–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Mobility Managment State Diagram 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Idle to Ready 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ready to Standby 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standby to Ready 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standby to Idle 4–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ready to Idle 4–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mobile Identity 4–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Timing Advance 4–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the BSS 4–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radio Link Control (RLC) Layer 4–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Medium Access Control (MAC) Layer 4–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Physical Layer 4–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Channel Coding Schemes 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme CS-1 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 2 (CS-2) 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 3 (CS-3) 4–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 4 (CS-4) 4–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the GPRS MS 4–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Quality of Service 4–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Precedence Class 4–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Delay Class 4–38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reliability Class 4–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 5GPRS Signalling i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Objectives 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Attach 5–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Detach 5–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PDP Context Activation 5–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MS PDP Context Activation 5–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Network-Requested PDP Context Activation 5–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Paging for GPRS Downlink Transfer 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Transfer – MS Originated 5–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Transfer – MS Terminated 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Paging 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Downlink Packet Transfer 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Release of the Resources 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Chapter 6Future Enhancements i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Objectives 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



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Mobile Evolution 6–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HSCSD 6–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Enhanced General Packet Radio Service (E–GPRS) 6–6. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Enhanced Data Rates for GSM Evolution (EDGE) 6–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UMTS 6–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

User Benefits of UMTS 6–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UMTS Future Vision 6–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Glossary of Terms i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A Glos–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B Glos–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C Glos–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

D Glos–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

E Glos–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F Glos–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G Glos–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I Glos–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L Glos–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

M Glos–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

N Glos–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P Glos–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Q Glos–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

R Glos–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

S Glos–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T Glos–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

U Glos–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

V Glos–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



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ISSUE 1 REVISION 3 General information



1

General information

Important notice

If this manual was obtained when you attended a Motorola training course, it will not beupdated or amended by Motorola. It is intended for TRAINING PURPOSES ONLY. If itwas supplied under normal operational circumstances, to support a major softwarerelease, then corrections will be supplied automatically by Motorola in the form ofGeneral Manual Revisions (GMRs).

Purpose

Motorola Global System for Mobile Communications (GSM) Technical Education manualsare intended to support the delivery of Technical Education only and are not intended toreplace the use of Customer Product Documentation.

Failure to comply with Motorola’s operation, installation and maintenanceinstructions may, in exceptional circumstances, lead to serious injury or death.

WARNING

These manuals are not intended to replace the system and equipment training offered byMotorola, although they can be used to supplement and enhance the knowledge gainedthrough such training.

About thismanual

ISSUE 1 REVISION 3General information



2

Cross references

Throughout this manual, cross references are made to the chapter numbers and sectionnames. The section name cross references are printed bold in text.

This manual is divided into uniquely identified and numbered chapters that, in turn, aredivided into sections. Sections are not numbered, but are individually named at the topof each page, and are listed in the table of contents.

Text conventions

The following conventions are used in the Motorola GSM manuals to represent keyboardinput text, screen output text and special key sequences.

Input

Characters typed in at the keyboard are shown like this.

Output

Messages, prompts, file listings, directories, utilities, and environmentalvariables that appear on the screen are shown like this.

Special key sequences

Special key sequences are represented as follows:

CTRL-c Press the Control and c keys at the same time.

ALT-f Press the Alt and f keys at the same time.

| Press the pipe symbol key.

CR or RETURN Press the Return (Enter) key. The Return key isidentified with the ↵ symbol on both the X terminal andthe SPARCstation keyboards. The SPARCstationkeyboard Return key is also identified with the wordReturn.

ISSUE 1 REVISION 3 First aid in case of electric shock



3

First aid in case of electric shock

Warning

Do not touch the victim with your bare hands until the electric circuit isbroken.Switch off. If this is not possible, protect yourself with dry insulatingmaterial and pull or push the victim clear of the conductor.

WARNING

Artificialrespiration

In the event of an electric shock it may be necessary to carry out artificial respiration.Send for medical assistance immediately.

Burns treatment

If the patient is also suffering from burns, then, without hindrance to artificial respiration,carry out the following:

1. Do not attempt to remove clothing adhering to the burn.

2. If help is available, or as soon as artificial respiration is no longer required, coverthe wound with a dry dressing.

3. Do not apply oil or grease in any form.

ISSUE 1 REVISION 3Reporting safety issues



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Reporting safety issues

Introduction

Whenever a safety issue arises, carry out the following procedure in all instances.Ensure that all site personnel are familiar with this procedure.

Procedure

Whenever a safety issue arises:

1. Make the equipment concerned safe, for example, by removing power.

2. Make no further attempt to tamper with the equipment.

3. Report the problem directly to GSM MCSC +44 (0)1793 430040 (telephone) andfollow up with a written report by fax +44 (0)1793 430987 (fax).

4. Collect evidence from the equipment under the guidance of the MCSC.

ISSUE 1 REVISION 3 Warnings and cautions



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Warnings and cautions

Introduction

The following describes how warnings and cautions are used in this manual and in allmanuals of the Motorola GSM manual set.

Warnings

Definition

A warning is used to alert the reader to possible hazards that could cause loss of life,physical injury, or ill health. This includes hazards introduced during maintenance, forexample, the use of adhesives and solvents, as well as those inherent in the equipment.

Example and format

Do not look directly into fibre optic cables or optical data in/out connectors.Laser radiation can come from either the data in/out connectors orunterminated fibre optic cables connected to data in/out connectors.

WARNING

Cautions

Definition

A caution means that there is a possibility of damage to systems, or individual items ofequipment within a system. However, this presents no danger to personnel.

Example and format

Do not use test equipment that is beyond its calibration due date when testingMotorola base stations.

CAUTION

ISSUE 1 REVISION 3General warnings



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General warnings

Introduction

Observe the following warnings during all phases of operation, installation andmaintenance of the equipment described in the Motorola GSM manuals. Failure tocomply with these warnings, or with specific warnings elsewhere in the Motorola GSMmanuals, violates safety standards of design, manufacture and intended use of theequipment. Motorola assumes no liability for the customer’s failure to comply with theserequirements.

Warning labelsPersonnel working with or operating Motorola equipment must comply with any warninglabels fitted to the equipment. Warning labels must not be removed, painted over orobscured in any way.

Specificwarnings

Warnings particularly applicable to the equipment are positioned on the equipment andwithin the text of this manual. These must be observed by all personnel at all times whenworking with the equipment, as must any other warnings given in text, on the illustrationsand on the equipment.

High voltageCertain Motorola equipment operates from a dangerous high voltage of 230 V ac singlephase or 415 V ac three phase mains which is potentially lethal. Therefore, the areaswhere the ac mains power is present must not be approached until the warnings andcautions in the text and on the equipment have been complied with.

To achieve isolation of the equipment from the ac supply, the mains input isolator mustbe set to off and locked.

Within the United Kingdom (UK) regard must be paid to the requirements of theElectricity at Work Regulations 1989. There may also be specific country legislationwhich need to be complied with, depending on where the equipment is used.

RF radiationHigh RF potentials and electromagnetic fields are present in the base station equipmentwhen in operation. Ensure that all transmitters are switched off when any antennaconnections have to be changed. Do not key transmitters connected to unterminatedcavities or feeders.

Refer to the following standards:

� ANSI IEEE C95.1-1991, IEEE Standard for Safety Levels with Respect to HumanExposure to Radio Frequency Electromagnetic Fields, 3kHz to 300GHz.

� CENELEC 95 ENV 50166-2, Human Exposure to Electromagnetic Fields HighFrequency (10kHz to 300GHz).

Laser radiationDo not look directly into fibre optic cables or optical data in/out connectors. Laserradiation can come from either the data in/out connectors or unterminated fibre opticcables connected to data in/out connectors.

ISSUE 1 REVISION 3 General warnings



7

Liftingequipment

When dismantling heavy assemblies, or removing or replacing equipment, the competentresponsible person must ensure that adequate lifting facilities are available. Whereprovided, lifting frames must be used for these operations. When equipments have to bemanhandled, reference must be made to the Manual Handling of Loads Regulations1992 (UK) or to the relevant manual handling of loads legislation for the country in whichthe equipment is used.

Do not ...... substitute parts or modify equipment.

Because of the danger of introducing additional hazards, do not install substitute parts orperform any unauthorized modification of equipment. Contact Motorola if in doubt toensure that safety features are maintained.

Battery supplies

Do not wear earth straps when working with standby battery supplies.

Toxic material

Certain Motorola equipment incorporates components containing the highly toxic materialBeryllium or its oxide Beryllia or both. These materials are especially hazardous if:

� Beryllium materials are absorbed into the body tissues through the skin, mouth, ora wound.

� The dust created by breakage of Beryllia is inhaled.

� Toxic fumes are inhaled from Beryllium or Beryllia involved in a fire.

See the Beryllium health and safety precautions section for further information.

ISSUE 1 REVISION 3Human exposure to radio frequency energy (PCS1900 only)



8

Human exposure to radio frequency energy (PCS1900 only)

IntroductionThis equipment is designed to generate and radiate radio frequency (RF) energy. Itshould be installed and maintained only by trained technicians. Licensees of the FederalCommunications Commission (FCC) using this equipment are responsible for insuringthat its installation and operation comply with FCC regulations designed to limit humanexposure to RF radiation in accordance with the American National Standards InstituteIEEE Standard C95.1-1991, IEEE Standard for Safety Levels with Respect to HumanExposure to Radio Frequency Electromagnetic Fields, 3kHz to 300GHz.

DefinitionsThis standard establishes two sets of maximum permitted exposure limits, one forcontrolled environments and another, that allows less exposure, for uncontrolledenvironments. These terms are defined by the standard, as follows:

Uncontrolled environmentUncontrolled environments are locations where there is the exposure of individuals whohave no knowledge or control of their exposure. The exposures may occur in livingquarters or workplaces where there are no expectations that the exposure levels mayexceed those shown for uncontrolled environments in the table of maximum permittedexposure ceilings.

Controlled environment

Controlled environments are locations where there is exposure that may be incurred bypersons who are aware of the potential for exposure as a concomitant of employment, byother cognizant persons, or as the incidental result of transient passage through areaswhere analysis shows the exposure levels may be above those shown for uncontrolledenvironments but do not exceed the values shown for controlled environments in thetable of maximum permitted exposure ceilings.

Maximumpermittedexposures

The maximum permitted exposures prescribed by the standard are set in terms ofdifferent parameters of effects, depending on the frequency generated by the equipmentin question. At the frequency range of this Personal Communication System equipment,1930-1970MHz, the maximum permitted exposure levels are set in terms of powerdensity, whose definition and relationship to electric field and magnetic field strengths aredescribed by the standard as follows:

Power density (S)Power per unit area normal to the direction of propagation, usually expressed in units ofwatts per square metre (W/m2) or, for convenience, units such as milliwatts per squarecentimetre (mW/cm2). For plane waves, power density, electric field strength (E) andmagnetic field strength (H) are related by the impedance of free space, 377 ohms. Inparticular,

� ��

��

where E and H are expressed in units of V/m and A/m, respectively, and S in units ofW/m2. Although many survey instruments indicate power density units, the actualquantities measured are E or E2 or H or H2.

ISSUE 1 REVISION 3 Human exposure to radio frequency energy (PCS1900 only)



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Maximumpermittedexposureceilings

Within the frequency range, the maximum permitted exposure ceiling for uncontrolledenvironments is a power density (mW/cm2) that equals f/1500, where f is the frequencyexpressed in MHz, and measurements are averaged over a period of 30 minutes. Themaximum permitted exposure ceiling for controlled environments, also expressed inmW/cm2, is f/300 where measurements are averaged over 6 minutes. Applying theseprinciples to the minimum and maximum frequencies for which this equipment is intendedto be used yields the following maximum permitted exposure levels:

Uncontrolled Environment Controlled Environment

1930MHz 1970MHz 1930MHz 1970MHz

Ceiling 1.287mW/cm2 1.313mW/cm2 6.433mW/cm2 6.567mW/cm2

If you plan to operate the equipment at more than one frequency, compliance should beassured at the frequency which produces the lowest exposure ceiling (among thefrequencies at which operation will occur).

Licensees must be able to certify to the FCC that their facilities meet the above ceilings.Some lower power PCS devices, 100 milliwatts or less, are excluded from demonstratingcompliance, but this equipment operates at power levels orders of magnitude higher, andthe exclusion is not applicable.

Whether a given installation meets the maximum permitted exposure ceilings depends, inpart, upon antenna type, antenna placement and the output power to which thisequipment is adjusted. The following example sets forth the distances from the antennato which access should be prevented in order to comply with the uncontrolled andcontrolled environment exposure limits as set forth in the ANSI IEEE standards andcomputed above.

ISSUE 1 REVISION 3Human exposure to radio frequency energy (PCS1900 only)



10

Examplecalculation

For a base station with the following characteristics, what is the minimum distance fromthe antenna necessary to meet the requirements of an uncontrolled environment?

Transmit frequency 1930MHz

Base station cabinet output power, P +39.0dBm (8 watts)

Antenna feeder cable loss, CL 2.0dB

Antenna input power Pin P–CL = +39.0–2.0 = +37.0dB (5watts)

Antenna gain, G 16.4dBi (43.65)

Using the following relationship:

� ��

��

Where W is the maximum permissible power density in W/m2 and r is the safe distancefrom the antenna in metres, the desired distance can be calculated as follows:

� ��

��

��

��

where W = 12.87 W/m2 was obtained from table listed above and converting frommW/cm2 to W/m2.

The above result applies only in the direction of maximum radiation of theantenna. Actual installations may employ antennas that have defined radiationpatterns and gains that differ from the example set forth above. The distancescalculated can vary depending on the actual antenna pattern and gain.

NOTE

Power densitymeasurements

While installation calculations such as the above are useful and essential in planning anddesign, validation that the operating facility using this equipment actually complies willrequire making power density measurements. For information on measuring RF fields fordetermining compliance with ANSI IEEE C95.1-1991, see IEEE Recommended Practicefor the Measure of Potentially Hazardous Electromagnetic Fields - RF and Microwave,IEEE Std C95.3-1991. Copies of IEEE C95.1-1991 and IEEE C95.3-1991 may bepurchased from the Institute of Electrical and Electronics Engineers, Inc., Attn:Publication Sales, 445 Hoes Lane, P.O. Box 1331, Piscattaway, NJ 08855-1331,(800) 678-IEEE or from ANSI, (212) 642-4900. Persons responsible for installation of thisequipment are urged to consult these standards in determining whether a giveninstallation complies with the applicable limits.

Other equipmentWhether a given installation meets ANSI standards for human exposure to radiofrequency radiation may depend not only on this equipment but also on whether theenvironments being assessed are being affected by radio frequency fields from otherequipment, the effects of which may add to the level of exposure. Accordingly, the overallexposure may be affected by radio frequency generating facilities that exist at the timethe licensee’s equipment is being installed or even by equipment installed later.Therefore, the effects of any such facilities must be considered in site selection and indetermining whether a particular installation meets the FCC requirements.

ISSUE 1 REVISION 3 Beryllium health and safety precautions



11

Beryllium health and safety precautions

Introduction

Beryllium (Be), is a hard silver/white metal. It is stable in air, but burns brilliantly inOxygen.

With the exception of the naturally occurring Beryl ore (Beryllium Silicate), all Berylliumcompounds and Beryllium metal are potentially highly toxic.

Health issues

Beryllium Oxide is used within some components as an electrical insulator. Captivewithin the component it presents no health risk whatsoever. However, if the componentshould be broken open and the Beryllium Oxide, which is in the form of dust, released,there exists the potential for harm.

Inhalation

Inhalation of Beryllium Oxide can lead to a condition known as Berylliosis, the symptomsof Berylliosis are similar to Pneumonia and may be identified by all or any of thefollowing:

Mild poisoning causes fever, shortness of breath, and a cough that producesyellow/green sputum, or occasionally bloodstained sputum. Inflammation of the mucousmembranes of the nose, throat, and chest with discomfort, possibly pain, and difficultywith swallowing and breathing.

Severe poisoning causes chest pain and wheezing which may progress to severeshortness of breath due to congestion of the lungs. Incubation period for lung symptomsis 2–20 days.

Exposure to moderately high concentrations of Beryllium in air may produce a veryserious condition of the lungs. The injured person may become blue, feverish with rapidbreathing and raised pulse rate. Recovery is usual but may take several months. Therehave been deaths in the acute stage.

Chronic response. This condition is more truly a general one although the lungs aremainly affected. There may be lesions in the kidneys and the skin. Certain featuressupport the view that the condition is allergic. There is no relationship between thedegree of exposure and the severity of response and there is usually a time lag of up to10 years between exposure and the onset of the illness. Both sexes are equallysusceptible. The onset of the illness is insidious but only a small number of exposedpersons develop this reaction.

First aid

Seek immediate medical assistance. The casualty should be removed immediately fromthe exposure area and placed in a fresh air environment with breathing supported withOxygen where required. Any contaminated clothing should be removed. The casualtyshould be kept warm and at rest until medical aid arrives.

ISSUE 1 REVISION 3Beryllium health and safety precautions



12

Skin contact

Possible irritation and redness at the contact area. Persistent itching and blisterformations can occur which usually resolve on removal from exposure.

First aid

Wash area thoroughly with soap and water. If skin is broken seek immediate medicalassistance.

Eye contact

May cause severe irritation, redness and swelling of eyelid(s) and inflammation of themucous membranes of the eyes.

First aid

Flush eyes with running water for at least 15 minutes. Seek medical assistance as soonas possible.

Handlingprocedures

Removal of components from printed circuit boards (PCBs) is to take place only atMotorola approved repair centres.

The removal station will be equipped with extraction equipment and all other protectiveequipment necessary for the safe removal of components containing Beryllium Oxide.

If during removal a component is accidently opened, the Beryllium Oxide dust is to bewetted into a paste and put into a container with a spatula or similar tool. Thespatula/tool used to collect the paste is also to be placed in the container. The containeris then to be sealed and labelled. A suitable respirator is to be worn at all times duringthis operation.

Components which are successfully removed are to be placed in a separate bag, sealedand labelled.

Disposalmethods

Beryllium Oxide or components containing Beryllium Oxide are to be treated ashazardous waste. All components must be removed where possible from boards and putinto sealed bags labelled Beryllium Oxide components. These bags must be given to thesafety and environmental adviser for disposal.

Under no circumstances are boards or components containing Beryllium Oxide to be putinto the general waste skips or incinerated.

Product life cycleimplications

Motorola GSM and analogue equipment includes components containing Beryllium Oxide(identified in text as appropriate and indicated by warning labels on the equipment).These components require specific disposal measures as indicated in the preceding(Disposal methods) paragraph. Motorola will arrange for the disposal of all suchhazardous waste as part of its Total Customer Satisfaction philosophy and will arrangefor the most environmentally “friendly” disposal available at that time.

ISSUE 1 REVISION 3 General cautions



13

General cautions

Introduction

Observe the following cautions during operation, installation and maintenance of theequipment described in the Motorola GSM manuals. Failure to comply with thesecautions or with specific cautions elsewhere in the Motorola GSM manuals may result indamage to the equipment. Motorola assumes no liability for the customer’s failure tocomply with these requirements.

Caution labels

Personnel working with or operating Motorola equipment must comply with any cautionlabels fitted to the equipment. Caution labels must not be removed, painted over orobscured in any way.

Specific cautions

Cautions particularly applicable to the equipment are positioned within the text of thismanual. These must be observed by all personnel at all times when working with theequipment, as must any other cautions given in text, on the illustrations and on theequipment.

Fibre optics

The bending radius of all fibre optic cables must not be less than 30 mm.

Static discharge

Motorola equipment contains CMOS devices that are vulnerable to static discharge.Although the damage caused by static discharge may not be immediately apparent,CMOS devices may be damaged in the long term due to static discharge caused bymishandling. Wear an approved earth strap when adjusting or handling digital boards.

See Devices sensitive to static for further information.

ISSUE 1 REVISION 3Devices sensitive to static



14

Devices sensitive to static

Introduction

Certain metal oxide semiconductor (MOS) devices embody in their design a thin layer ofinsulation that is susceptible to damage from electrostatic charge. Such a charge appliedto the leads of the device could cause irreparable damage.

These charges can be built up on nylon overalls, by friction, by pushing the hands intohigh insulation packing material or by use of unearthed soldering irons.

MOS devices are normally despatched from the manufacturers with the leads shortedtogether, for example, by metal foil eyelets, wire strapping, or by inserting the leads intoconductive plastic foam. Provided the leads are shorted it is safe to handle the device.

Special handlingtechniques

In the event of one of these devices having to be replaced observe the followingprecautions when handling the replacement:

� Always wear an earth strap which must be connected to the electrostatic point(ESP) on the equipment.

� Leave the short circuit on the leads until the last moment. It may be necessary toreplace the conductive foam by a piece of wire to enable the device to be fitted.

� Do not wear outer clothing made of nylon or similar man made material. A cottonoverall is preferable.

� If possible work on an earthed metal surface. Wipe insulated plastic work surfaceswith an anti-static cloth before starting the operation.

� All metal tools should be used and when not in use they should be placed on anearthed surface.

� Take care when removing components connected to electrostatic sensitivedevices. These components may be providing protection to the device.

When mounted onto printed circuit boards (PCBs), MOS devices are normally lesssusceptible to electrostatic damage. However PCBs should be handled with care,preferably by their edges and not by their tracks and pins, they should be transferreddirectly from their packing to the equipment (or the other way around) and never leftexposed on the workbench.

ISSUE 1 REVISION 3 Motorola GSM manual set



15

Motorola GSM manual set

Introduction

The following manuals provide the information needed to operate, install and maintain theMotorola GSM equipment.

Generic manuals

The following are the generic manuals in the GSM manual set, these manuals arerelease dependent:

Categorynumber

Name Cataloguenumber

GSM-100-101 System Information: General 68P02901W01

GSM-100-201 Operating Information: GSM System Operation 68P02901W14

GSM-100-311 Technical Description: OMC in a GSM System 68P02901W31

GSM-100-313 Technical Description: OMC Database Schema 68P02901W34

GSM-100-320 Technical Description: BSS Implementation 68P02901W36

GSM-100-321 Technical Description: BSS CommandReference

68P02901W23

GSM-100-403 Installation & Configuration: GSM SystemConfiguration

68P02901W17

GSM-100-423 Installation & Configuration: BSS Optimization 68P02901W43

GSM-100-501 Maintenance Information: Alarm Handling atthe OMC

68P02901W26

GSM-100-521 Maintenance Information: Device StateTransitions

68P02901W57

GSM-100-523 Maintenance Information: BSS FieldTroubleshooting

68P02901W51

GSM-100-503 Maintenance Information: GSM StatisticsApplication

68P02901W56

GSM-100-721 Software Release Notes: BSS/RXCDR 68P02901W72

Tandem OMC

The following Tandem OMC manuals are part of the GSM manual set for systemsdeploying Tandem S300 and 1475:

Categorynumber


GSM-100-202 Operating Information: OMC SystemAdministration

68P02901W13

GSM-100-712 Software Release Notes: OMC System 68P02901W71

ISSUE 1 REVISION 3Motorola GSM manual set



16

Scaleable OMC

The following Scaleable OMC manuals replace the equivalent Tandem OMC manuals inthe GSM manual set:

Categorynumber


GSM-100-202 Operating Information: Scaleable OMC SystemAdministration

68P02901W19

GSM-100-413 Installation & Configuration: Scaleable OMCClean Install

68P02901W47

GSM-100-712 Software Release Notes: Scaleable OMCSystem

68P02901W74

Related manuals

The following are related Motorola GSM manuals:

Categorynumber


GSM-001-103 System Information: BSS Equipment Planning 68P02900W21

GSM-002-103 System Information: DataGen 68P02900W22

GSM-005-103 System Information: Advance OperationalImpact

68P02900W25

GSM-008-403 Installation & Configuration: Expert Adviser 68P02900W36

Service manuals

The following are the service manuals in the GSM manual set, these manuals are notrelease dependent. The internal organization and makeup of service manual sets mayvary, they may consist of from one to four separate manuals, but they can all be orderedusing the overall catalogue number shown below:

Categorynumber


GSM-100-020 Service Manual: BTS 68P02901W37

GSM-100-030 Service Manual: BSC/RXCDR 68P02901W38

GSM-105-020 Service Manual: M-Cell2 68P02901W75

GSM-106-020 Service Manual: M-Cell6 68P02901W85

GSM-201-020 Service Manual: M-Cellcity 68P02901W95

GSM-202-020 Service Manual: M-Cellaccess 68P02901W65

GSM-101-SERIES ExCell4 Documentation Set 68P02900W50

GSM-103-SERIES ExCell6 Documentation Set 68P02900W70

GSM-102-SERIES TopCell Documentation Set 68P02901W80

GSM-200-SERIES M-Cellmicro Documentation Set 68P02901W90

ISSUE 1 REVISION 3 Motorola GSM manual set



17

Category number

The category number is used to identify the type and level of a manual. For example,manuals with the category number GSM-100-2xx contain operating information.

Cataloguenumber

The Motorola 68P catalogue number is used to order manuals.

Orderingmanuals

All orders for Motorola manuals must be placed with your Motorola Local Office orRepresentative. Manuals are ordered using the catalogue number. Remember, specifythe manual issue required by quoting the correct suffix letter.

ISSUE 1 REVISION 3Motorola GSM manual set



18



i

Chapter 1

GSM Review

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 1GSM Review i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 1–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Evolution of GSM 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 1 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 2 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Phase 2+ 1–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Network Architecture 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Base Station System (BSS) 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Mobile Station (MS) 1–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mobile Services Switching Centre (MSC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Home Location Register (HLR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Visitor Location Register (VLR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Equipment Identity Register (EIR) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Authentication Centre (AUC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Echo Canceller (EC) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Interworking Function (IWF) 1–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Operations and Maintenance Centre Radio (OMC-R) 1–6. . . . . . . . . . . . . . . . . . . . . .

Interworking Function (IWF) 1–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Channel Combinations 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Timeslot Allocation 1–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GSM Channel Coding 1–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

14.4 Kbps Data Rate 1–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Voice and Data through GSM 1–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Data connection through GSM 1–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv

ISSUE 1 REVISION 3 Objectives



1–1

ObjectivesOn completion of this chapter the student should be able to:

� Explain the Evolution of GSM.

� State the functions of the GSM Network entities.

� Explain GSM Channel Coding and Data connection through GSM.

ISSUE 1 REVISION 3The Evolution of GSM



1–2

The Evolution of GSM

Phase 1

At the launch of GSM in 1991, the initial services offered were only the basicrequirements of telephony and emergency calls. Data, Short Message Service and alimited set of supplementary services were also fully defined and began to appear innetworks progressively over the following months and years.

Phase 2

Development continued with the Specifications and in 1995 they were frozen for asecond time and called the Phase 2 Specifications. Phase 2 mobile phones appeared inthe market place in the following year. The Phase 2 Specifications included the following:

� Group 3 FAX

� Half rate speech

� Enhanced full rate speech

� Hierarchical cells

� Improved cell selection and reselection

� Second cipher algorithm

� More Supplementary Services

Phase 2+

Development of the specifications still continued after Phase 2 but releases of the newspecifications were referred to as Phase 2+. The purpose of this terminology was toindicate a progression towards Third Generation Systems. Phase 2+ is not a singlerelease but a phased yearly release of developing features and services. Among themore significant developments included in Phase 2+ are:

� 14.4kbps user data

� High Speed Circuit Switched Data

� General Packet Radio Service

� SIM Application Toolkit

� Voice Group Call Service

� CAMEL (Intelligent Networks)

� Support of Optimal Routing

ISSUE 1 REVISION 3 The Evolution of GSM



1–3

Evolution of GSM

CPO7_1_1

1990 – 1995 – 1996 –

Phase 1: Phase 2: Phase 2+:

Basic Services Enhanced VoiceEnhanced ServicesIncreased Capacity Increased Data RatesIncreased User Functionality

Data Services: 300–9600 bps

SMSYour dinner is

in the dog

GSM 900Macrocells

DCS 1800Macrocells

GSM 900 Microcells

Macro cell

Microcell

PicoCells

PicoCells

Macro cell

Supplementary services:Call forwardingCall barring

Basic TelephonyEmergency

Services

ISSUE 1 REVISION 3Network Architecture



1–4

Network Architecture

Base StationSystem (BSS)

The BSS is a collective term for the RXCDR, BSC and BTSs. The philosophy behind theBSS is that it takes full responsibility for all radio aspects of GSM, removing thesefunctions from the MSC.

Base Station Controller (BSC)

A number of BTSs will be connected to and controlled by a BSC. The BSCs mainfunction is control of BTSs and switching functions.

Remote Transcoder (RXCDR)

The RXCDR provides the interface between the MSC and BSS. Speech within the PSTNis at a rate of 64 kbps and this is also true within the MSC. The RXCDR reduces this rateto 13 kbps for transmission over the Air Interface.

Base Transceiver Station (BTS)

This network element the radio transceivers that communicate with mobile phones, andantenna system and supporting hardware and software.

Mobile Station(MS)

The MS is the collective term given to the ME and SIM combination.

Mobile Equipment (ME)

This is the physical hardware of the mobile phone.

Subscriber Identity Module (SIM)

The SIM is a smart card that is inserted into the mobile phone and provides the user’sidentity. The SIM supports:

� User identification

� Location information

� Security

� Ciphering functions.

ISSUE 1 REVISION 3 Network Architecture



1–5

Network Management Centre

CPO7_1_2

RXCDR

BSC

BTS BTS BTS

Mobile Station (MS)

OMC–R

OMC–S

NMC

NSS

ISSUE 1 REVISION 3Mobile Services Switching Centre (MSC)



1–6

Mobile Services Switching Centre (MSC)The MSC is the heart of the fixed infrastructure and is effectively a telephone exchangefor GSM mobile calls. It is responsible for:

� Making the appropriate connections to establish telephone calls

� Linking the GSM network into the PSTN

� Billing

Home LocationRegister (HLR)

The HLR provides a permanent record of all subscribers who belong to the homenetwork. There is one HLR per network.

Visitor LocationRegister (VLR)

The VLR holds subscriber details temporarily whilst a user is within a particulargeographical area. The VLR therefore holds records for subscribers of the home networkand subscribers from other networks. There is usually one VLR per MSC coveringtypically the area of a ‘city’.

EquipmentIdentity Register(EIR)

The EIR is concerned with the security features of the Mobile Equipment. That is, astolen MS may be recorded in the EIR and prevented from accessing the network.

AuthenticationCentre (AUC)

The AUC is concerned with security and ciphering.

Echo Canceller(EC)

The EC will provide cancellation of up to 68 milliseconds of delay and prevent any echodue to combining of signals from 4 wires to 2 wires.

InterworkingFunction (IWF)

The IWF provides an interface between GSM and other networks involved in thetransport of user data.

Operations andMaintenanceCentre Radio(OMC-R)

The OMC-R is a centralised control point from which the performance of the network canbe remotely monitored and controlled. There will normally be one OMC-R per regionalarea on the network.

ISSUE 1 REVISION 3 Mobile Services Switching Centre (MSC)



1–7

Mobile Services Switching Centre (MSC)

CPO7_1_3

RXCDR

BSC

BTS BTS BTS

Mobile Station (MS)

MSC

IWF

EC

VLR

AUC HLR

EIR PSTN

DataNetworks

NSS

ISSUE 1 REVISION 3Interworking Function (IWF)



1–8

Interworking Function (IWF)The interconnection of the MSC with certain networks requires adaptation of the GSMtransmission peculiarities to those of the partner network. These adaptations are theInterworking Function (IWF).

In basic terms the IWF is a transmission and protocol adaptation equipment. It enablesinterconnection with networks such as PSPDNs (Packet–Switched Public DataNetworks) or Circuit–Switched Public Data Networks (CSPDNs), but also exists when thepartner network is simply the PSTN or the ISDN.

The IWF also incorporates a ‘modem bank’, which may be used when, for example, theGSM Data Terminal Equipment (DTE) exchanges data with a land DTE connected via ananalogue modem.

The IWF function can be incorporated as part of the MSC or performed by separateequipment.

ISSUE 1 REVISION 3 Interworking Function (IWF)



1–9

Interworking Function (IWF)

CPO7_1_4

MSC

IWF

EC

VLR

AUC HLR

EIR

Base Station System

Other Network

Server

ISSUE 1 REVISION 3Channel Combinations



1–10

Channel CombinationsThe different logical channels can be combined into one frame to allow a saving in thefrequency spectrum.

Common combinations include:

� Traffic Combination TCH/FACCH + SACCH

� BCCH Combination BCCH + CCCH

� DCCH Combination SDCCH + SACCH

� Combined Channel Combination BCCH + CCCH + SDCCH + SACCH

TimeslotAllocation

Some channel combinations can be sent on any timeslot but others have dedicatedtimeslots, the table opposite lists the restrictions.

ISSUE 1 REVISION 3 Channel Combinations



1–11

Combination Timeslots

CPO7_1_5

TS1 TS2 TS3 TS4 TS5 TS6 TS7

BCCHCCCH SDCCH

TS0

TFC TFC TFC TFC TFC TFC

Combination

Traffic

Broadcast

Dedicated

Combined

Timeslot

Any

0, 2, 4, 6 but 0 first

Any

0 only

ISSUE 1 REVISION 3GSM Channel Coding



1–12

GSM Channel CodingThe process of passing speech and data over the air interface is complicated andinvolves many subprocesses that are essential to GSM. Without them the received signalwould be full of errors and unintelligible, as the radio path is a very hostile environment toour sequence of ones and zeros.

Before the actual radio path characteristics are dealt with we must first look at what canbe done to the speech prior to radio transmission, the treatment of data is not exactly thesame, but is very similar. The process can be broken down into 6 simple blocks:

� Digitising and Source coding – conversion of speech into digital.

� Channel Coding – application of forward error correction techniques and blockconvolutional coding.

� Bit interleaving – spreading the information across many timeslots to improve therobustness of the radio signal to noise.

� Ciphering – security of the radio signal to eaves droppers.

� Burst Formatting – format the information into the bursts transmitted in thetimeslots.

� Modulation – positioning the information onto a carrier medium that can be usedon a radio link.

ISSUE 1 REVISION 3 GSM Channel Coding



1–13

GSM Channel Coding

CPO7_1_6

Digitising andSource Encoding

ChannelCoding Bit interleaving

BurstFormatting

Ciphering

Modulation

13 kbps 22.8 kbps 33.8 kbps

8 timeslots270.8 kbps

Tx and antennaData input

MS

ISSUE 1 REVISION 314.4 Kbps Data Rate



1–14

14.4 Kbps Data RateWe already know that GSM supports a user rate of 9.6 kbps resulting in a 12 kbps radiointerface rate and the aim of this work item was to improve on that with a minimal amountof changes to the current specifications. 14.4 kbps can be achieved by changing thepuncturing scheme used during the channel coding sequence and by transmitting 290bits (288 bits of user data) every 20ms as opposed to 240 bits. The 2 remaining bits arefor status and control information. This results in a radio interface rate of 14.5 kbpsinstead of 12 kbps but due to the puncturing scheme maintains a rate of 22.8 kbps overthe Air Interface.

ISSUE 1 REVISION 3 14.4 Kbps Data Rate



1–15

Channel Coding Sequence

CPO7_1_7

Block Code240 + 4

Half rateConvolutional Code

Puncturing488 – 32

Block Code290 + 4

Half rateConvolutional Code

Puncturing588 – 132

240 bits 244 bits 488 bits 456 bits

22.8 kbps


22.8 kbps

GSM at present – 12 kbps (9.6 kbps user rate)

Phase 2+ – 14.5 kbps (14.4 kbps user rate)

ISSUE 1 REVISION 3Voice and Data through GSM



1–16

Voice and Data through GSMThe most familiar method of transferring data to most people is by using the PSTN (tomake the connecton to the receiving party) and a modem (to make the connection to thePSTN). Although data is digital and the PSTN is digital, the ‘local loop’ connecting thefixed subscriber to the PSTN is analogue. The modem converts the digital data toanalogue in order to carry it to the PSTN.

This little bit of basic theory is very applicable to GSM simply because when a GSMsubscriber is transferring data over GSM there is a high probability that the other end ofthe link will be a PSTN connection to a modem. Other types of data transfer (e.g. a digitalconnection to a Packet Network) are very similar.

Mobile user data connection

A modem is still required because the PSTN accepts at its input, audio signals. It wouldbe reasonable to assume that the GSM network might be situated between the modemand the PSTN. This might have been possible in GSM but presented technicaldifficulties. Instead GSM was designed to fit between the laptop and the modem. Theentire GSM link is ‘inserted’ between the laptop and modem.

ISSUE 1 REVISION 3 Voice and Data through GSM



1–17

Voice and data through GSM

CPO7_1_8

Data and Control

DTE

DCE

ADC

64 kbps

PSTN

Analogue 3.1 kHz

ADC

Analogue 3.1 kHz

DCE/modem

GSM

MS

DTE

DTE

ISSUE 1 REVISION 3Data connection through GSM



1–18

Data connection through GSMThe output from the laptop is a maximum of 9.6kbps of data and RS232 control signals.The control signals must also be carried to the modem and increase the bit-rate to12kbps. Typically a ‘Data Card’ inserted into a PCMCIA slot of the laptop will convertthese signals (data and control) into a 12kbps serial bit stream for connecting to a mobilephone.

The mobile phone adds on bits for error protection and transmits across the Air Interfaceat 33.8kbps. This occupies one complete timeslot, as does a normal voice link.

At the BSS (BTS/BSC) the error protection bits are removed and the 12kbps of data aretransferred to the XCDR at 16kbps (as with speech, a padding process for transfer overE1 links).

The XCDR rate adapts this to 64kbps (padding) for transfer to the MSC.

Finally the MSC relays the signal to a GSM network entity known as the interworkingfunction (IWF). This contains a Rate Adapter which will remove the 64kbps padding,reconvert the serial 12kbps into the original 9.6kbps data plus control signals and feed tothe modem (also situated in the IWF).

When connecting to other networks e.g. ISDN or a Packet Network the arrangement isvery similar but the DCE is not a modem but ISDN connector or a PacketAssembler/Dissembler (PAD). These alternative DCEs are again situated in the IWF andrate adaptation through the GSM network is unchanged.

ISSUE 1 REVISION 3 Data connection through GSM



1–19

Data connection through GSM

CPO7_1_9

BTS

BSC

RXCDR

MSCRate Adapter

IWF

12 (64)

12 (64) kbps

12 (16) kbps

12 (16) kbps

12 (33.8) kbps

9.6 kbpsData and control

PSTN

9.6 kbps

12 kbps

PCMCIA

kbpsModem

DTE

DTE

ISSUE 1 REVISION 3Data connection through GSM



1–20



i

Chapter 2

GPRS Outline

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 2GPRS Outline i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 2–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Today’s use of Data 2–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Future Data Usage and Applications 2–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Industry Convergence 2–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Circuit and Packet Switching 2–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Circuit Switching 2–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Switching 2–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Datagrams and Virtual Circuits 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Datagrams 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Virtual Circuit 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Permanent Virtual Circuit (PVC) 2–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Symbian and Bluetooth 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Symbian 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Bluetooth 2–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Wireless Application Protocol 2–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS 2–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Infrastructure 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gateway GSN (GGSN) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Serving GPRS Support Node (SGSN) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Control Unit (PCU) 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MSC, HLR and VLR 2–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS network elements 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Gateway GPRS Support Node (GGSN) 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Serving GPRS Support Node (SGSN) 2–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Control Unit (PCU) 2–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Mobile Stations 2–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv




2–1


� Explain the difference between Circuit and Packet switching.

� State how Virtual Circuits are created.

� Explain the impact of Industry convergence toward Internet Protocol (IP).

� Explain the structure and function of a WAP network.

� Identify the GPRS entities and explain their functions.

ISSUE 1 REVISION 3Today’s use of Data



2–2

Today’s use of DataGSM was designed from the ground up for data transmission as well as voice, buttake–up has been slow. Wireless data currently produces a mere 2% of GSM networkrevenues (Finland has the highest, with 5%). Yet at the same time more people arebecoming mobile and by the end of the decade they will represent 30% of the workforce.

The need for faster, cheaper, smarter and better–managed services clearly exists withthe key service being the mobile intranet i.e. secure wireless access to the corporateenvironment over the Internet.

There are four main reasons for the slow take–up of wireless data systems:

� The notebook PC/phone link was (and still is) proprietary, so the PC card isexpensive.

� Voice and data required a user to use two devices, and carrying a phone about isirrelevant to a data–centric worker.

� The transfer rate of 9.6kbit/s, albeit with robust error correction, was perceived astoo low and the cost of mobile email and faxing as too high.

� The industry was not marketing a true solution – mobile data involves aconvergence of communications and computing technologies, and until recentlyusers had to apply the glue themselves.

ISSUE 1 REVISION 3 Today’s use of Data



2–3

Today’s use of Data

� 1–3% of network traffic– Data users are mainly premium subscribers.

� SMS – a small, growing number of products.

� Difficult to use (handset, PC connection).

� Cost – circuit based technology.

� Low data rate– Speed of 9.6 kbps or 14 kbps

ISSUE 1 REVISION 3Future Data Usage and Applications



2–4

Future Data Usage and ApplicationsThe introduction of any mobile multimedia services will be driven by actual user needs.For personal communications services to reach the hoped–for penetration rates of 70–80per cent, services must have mass–market appeal: they need to be easy to use andcost–justifiable.

With the fantastic growth in Internet / Intranet usage, however, demand is alreadygrowing for higher speeds in order to access corporate resources while on the move.This type of multimedia application demands high peak bit–rates in short bursts, while theinformation is downloaded, in one direction.

Another potential multimedia application is simultaneous voice and data, for example, forPC application sharing or shared whiteboard. Although this type of application does notrequire particularly high bit-rates, it does require real–time, continuous operation becauseof its voice content.

ISSUE 1 REVISION 3 Future Data Usage and Applications



2–5

Data growth – how much and why

CP07_2_02

Consensus of forecasts is that data will form at least 20% ofGSM traffic by 2005.

This implies at least 15 x today’s data volumeSource: Motorola

90

10

20

30

40

50

60

70

80

01995 20052000

Analysis HighTele FinlandAnalysis low

ISSUE 1 REVISION 3Industry Convergence



2–6

Industry ConvergenceVoice and data are converging and starting to be carried on the same networks, butopinions vary on how quickly this is happening and what impact it will have on the IT andtelcos. Businesses are wondering what benefits it will bring and how soon they shouldadd voice to their data networks.

Today the volume of data in telecomms networks has surpassed voice, Within 4 yearsthe big US telcos are predicting that 99% of telecomms traffic will be data. Already therehave been many merges, acquisitions and alliances spanning telecomms and IT asleading companies jostle for position, once such example is the partnership betweenMotorola & Cisco.

Many of the recent merges and acquisitions have been brought about by telecommsequipment companies buying up the IT companies that make Internet Protocol (IP)telephony products. These products allow data to be carried cheaply over networksbased on the IP protocol used on the internet. They can also be used to carry Voice overIP (VOIP) by converting it into small packets of data. In this way more voice calls can besent down a single line. Examples of such acquisitions include Alcatel buying Xylan,Nortel’s purchase of Bay Networks, Lucent acquiring Ascend and Nokia buying Ipsilon.

It is estimated that full IP networks will not be deployed until 2 years time. Some of themission elements include:

� Voice gateways

� End to end control

� QoS support (except when sent over another standard e.g. ATM)

� Network management facilities

One of the main benefits to the customer is that of reduced network infrastructure costsbecause there will be no need for separate data and telecomms networks.

ISSUE 1 REVISION 3 Industry Convergence



2–7

Industry Convergence

CP07_2_07

Computer Media

IP

Telecommunication

internet access

Mobilitymultimediareal time imageselectronic mail

mobile computing High speedservices

Personalservices

Mobility

wideband data servicesvideo telephonyISDN services

TV/Radio / Data contribution& distribution

interactive video servicesvideo on demandstreaming audio

MobilityWidebandservices

···

·····

····

ISSUE 1 REVISION 3Circuit and Packet Switching



2–8

Circuit and Packet SwitchingThe advantages of transferring data using packet switching as opposed to circuitswitching have long been recognised.

Circuit switching provides a fixed bandwidth channel over a unique path from user touser for the duration of the call. It is therefore inefficient when dealing with ‘bursty’ orVariable Bit Rate (VBR) traffic (e.g. data) as the maximum required bit rate must bemaintained throughout the duration of the call therefore leaving resources under-utilisedfor much of the time.

Packet switching can be used for data traffic that is generated in bursts and is thereforeideal for Variable Bit Rate data transport. The paths taken by successive packets maynot be the same. Overhead information is added to the data to enable the network toroute it correctly and the recipient has to assemble the packets in the correct sequence.Delays are also incurred when packets queue at switches. For constant bit rate voice andvideo it can cause a relatively high delay as well as uncertain queuing delays.

GSM has, until GPRS, used circuit switched connections. A bi-directional traffic channelis established and therefore chargeable, to the user for the duration of the call whethertraffic is actually being transferred or not.

Consider as an example the inefficiency of using the Internet and downloading largequantities of data. The uplink, though barely being used, is nevertheless an availableresource, which is being charged. Packet switching divides the data into individual,limited size containers (packets) and sends them through the network alongcommunication lines being shared by other channels.

ISSUE 1 REVISION 3 Circuit and Packet Switching



2–9

Circuit and Packet Switching

It’s All Mine!

Circuit Switching

A complete resource allocatedto an individual device

Which exit did you say?

Packet Switching

Devices share the availableresources

ISSUE 1 REVISION 3Circuit Switching



2–10

Circuit SwitchingThe diagram shows separate paths (circuits) A–B and A–C that are created through aCircuit Switched Data Network (CSDN). In this example, the paths are 64kb/s channels(timeslots) provided within an E1 TDM frame that operates at 2.048 Mb/s; the timeslotsare switched at the switching nodes in order to create the required paths.

The circuits are permanently provisioned and operate at fixed data rates (64kb/s);Nx64kb/s circuits could also be provisioned for higher bandwidth applications. Note thata duplex path (i.e. A/B and B/A) is provided.

Circuit switching takes place at the OSI physical layer, and there is no provision for errorcontrol or flow control. However, circuit switched paths are protocol transparent – theyprovide basic pipes for transmission. The same DTE interface (X.21 in this example) isusually required at each end of the circuit.

Circuit switched paths are generally suitable for applications that require a fixed, shortdelay e.g. voice and video. The bandwidth available is permanently dedicated to thecircuit and the paths are non-blocking. However, this is wasteful for many dataapplications which are bursty by nature, or which involve a short request / long response.

ISSUE 1 REVISION 3 Circuit Switching



2–11

Circuit Switching

Physical

CP07_2_04

B

CA S

S

S

Physical Physical Physical Physical

CSDN

L1

ISSUE 1 REVISION 3Packet Switching



2–12

Packet SwitchingIn a Packet Switched Data Network (PSDN ), data to be transmitted is first segmentedby the source DTE into message units called packets . Each packet includes thenetwork addresses of the source and destination DTEs. On receipt of each packet, thePacket Switch Exchange (PSE) stores it while inspecting the destination address; eachPSE has a routing table specifying the outgoing link(s) to be used for each destinationnetwork address. The PSE then forwards the packet on the appropriate link at the rateof that link. This method of working is known as store–and–forward .

A number of packets may arrive simultaneously at a PSE on different incoming links forforwarding on the same outgoing link. Packets may therefore experience unpredictablylong delays. (To prevent this, a maximum length is specified for each packet).

The PSDN has a meshed topology that offers multiple alternate routes for packets. Inthe diagram, there are two alternate routes between any pair of PSEs. The PSDNtherefore provides a resilient networking service.

As packet networks use store–and–forward, the two communicating DTEs can havedifferent access speeds to the network. The transmission links between PSEs are betterutilised because users only occupy bandwidth when data is being sent and a number ofsuch users can therefore “share” the available transmission bandwidth. This technique isknown as statistical multiplexing – a statistical gain is achieved because it is unlikelythat all users will be transmitting at the same time.

On packet switched networks, error control and flow control are performed on each link.Error control ensures that packets are delivered error–free and in sequence, and flowcontrol provides a method of reducing congestion during busy periods. Overheads forthese functions are carried by each packet and employed by each PSE at OSI Layers 2and 3.

Packet switching can achieve equipment economies because many DTEs can beconnected to a single PSDN access equipment.

Packets switching matches the characteristics of many data applications (occasional,bursty transfer of data). Its statistical nature means that it is efficient. It does not offer aconstant, low–delay performance and is not therefore suitable for delay sensitiveapplications e.g. voice and video.

ISSUE 1 REVISION 3 Packet Switching



2–13

Packet Switching

CP07_2_05

Data Packet where:

c = destination address

a = source address

B

C

D

A

PSDNPSE

PSEPSE

PSE

da

a c

a c

a b

cb

a c

L3L2L1

HigherLayers

X.25LAP.B

Physical

X.25LAP.B

Physical

X.25LAP.B

Physical

X.25LAP.B

Physical

HigherLayers

X.25LAP.B

Physical

ISSUE 1 REVISION 3Datagrams and Virtual Circuits



2–14

Datagrams and Virtual CircuitsThe two types of service normally supported by a PSDN are known as datagram andvirtual circuit services.

Datagrams

The datagram service is normally used for the transmission of short, single–packetmessages. Each packet that enters the network is treated as a self–contained entity withno relationship to other packets. The packets can be therefore be forwarded overdifferent routes to the same destination. Datagrams provide a connection–less service.

Virtual Circuit

The virtual circuit service is used when a message contains multiple packets. It is aconnection–oriented service.

Before any data packets are sent, the source DTE sends a call request packet to PSE1(see diagram) containing the network address of the destination DTE and a referencenumber called the Virtual Circuit Identifier (VCI) . PSE 1 notes the VCI and forwardsthe packet through the network according to the information contained in its routing table.It assigns a new VCI to the route PSE1 – PSE2, and updates its routing table as shown.

At PSE2, another VCI is assigned to the call request packet before it is forwarded on theoutgoing link to the destination DTE. Assuming that the call is accepted, an appropriateresponse packet is returned to the calling DTE. At this point, a virtual circuit (VC )exists between the two DTEs. During the subsequent data transfer phase, all datapackets relating to the call DTE1 – DTE2 are assigned the same VCIs along the virtualcircuit. In this way, the source and destination DTEs can readily distinguish betweenpackets arriving on the same link that relate to different calls – multiple calls are therebymultiplexed on to the same link.

All packets take the same route across the network and should therefore arrive insequence. The network addresses are only required in the initial call request and callaccept packets.

PermanentVirtual Circuit(PVC)

When the data transfer phase is complete, a clear–down packet is sent and the VCIsare released. If DTE1 frequently requires to communicate with DTE2, the VC may be leftpermanently established – this is known as a PVC. This can be more economical sincethe cost of the call will usually be based on the quantity of data transferred, not theduration, although the user must pay for the PVC facility.

ISSUE 1 REVISION 3 Datagrams and Virtual Circuits



2–15

Virtual Circuits

CP07_2_06

DTE1 DTE2

VCI(1) VCI(2) VCI(3)

Virtual Circuit

PSE11 2

PSE21 2

Routing Table – PSE1

IN OUT

VCI(1) / Link(1)

VCI(2) / Link(2)

VCI(2) / Link(2)

VCI(1) / Link(1)Routing Table – PSE2

IN OUT

VCI(2) / Link(1)

VCI(3) / Link(2)

VCI(3) / Link(2)

VCI(2) / Link(1)

ISSUE 1 REVISION 3Symbian and Bluetooth



2–16

Symbian and Bluetooth

Symbian

Symbian was launched in 1998 and is a joint venture between some of the leadingmobile and PDA manufacturers (Ericsson, Motorola, Nokia, Panasonic and Psion).Symbian owns, licenses, develops and supports EPOC technology which providessoftware, application frameworks and development tools for Wireless InformationDevices such as Communicators and Smart–phones. The EPOC technology includescustomisable user interfaces, colour support, fit–for–purpose application suites,advanced Internet connectivity and PC connectivity software. It is their third–generationoperating system for mobile ROM–based computing. It is multi–tasking, 32–bit OSsupporting a pen–based GUI and networking capabilities. It is component–based and canbe scaled from relatively large configurations for a fully functional handheld computer, tosmall configurations for embedded applications. EPOC is optimised for low–power,compact machines, and long–running, mission–critical, applications.

Bluetooth

Bluetooth is an open specification for wireless communications of data and voice. It isbased on a low–cost short–range radio link, built into a 9 x 9 mm microchip, and isdesigned to replace cables which are currently used to connect peripheral terminals anddevices.

Bluetooth technology enables connection of mobile computers, digital cellular phones,handheld devices, network access points and other mobile devices via wirelessshort–range radio links unimpeded by line–of–sight restrictions. Products are likely tobecome available at the end of 1999.

Bluetooth technology will increase the ease and breadth of wireless connectivity. Userswill be able to automatically receive e–mail on their notebook computers via the digitalcellular phones in their pockets or synchronise their primary PC with their handheldcomputer.

ISSUE 1 REVISION 3 Symbian and Bluetooth



2–17

Symbian

CP07_2_08

SymbianLinks applications

BluetoothLinks devices

WAPLinks Internet

ISSUE 1 REVISION 3Wireless Application Protocol



2–18

Wireless Application ProtocolBoth the wireless data market and the Internet are evolving network technologies, whichare growing very quickly and are continuously reaching new customers. The WirelessApplication Protocol (WAP) is positioned at the convergence of these two technologiesresulting in the WAP Forums efforts to promote industry– wide specifications fortechnology useful in developing applications and services that operate over wirelesscommunication networks. An application framework and network protocols have beenspecified for wireless devices such as mobile phones, pagers and personal digitalassistants (PDAs). The effort is aimed at enabling operators, manufacturers and contentdevelopers to meet the challenges in building advanced differentiated services andimplementations in a fast and flexible manner. The WAP Forum originally consisted ofthe manufacturers Ericsson, Motorola and Nokia together with the software houseUnwired Planet but there are now many more companies with a vested interest in mobiledata systems.

WAP is being promoted as a major breakthrough that will achieve universal Internetbased information access on wireless devices and as such allow software developers tobe able to write once for all networks world–wide. In addition, operators will be able toimplement gateways that work with many brands of phones and all applications andcontent. Also, handset manufacturers will be able to make high volume, and thus lowcost handsets, which can be implemented into all networks.

The Wireless Application Environment (WAE) is undertaking to build a general–purposeapplication environment based fundamentally on the World Wide Web (www)technologies and philosophies. The WAE architecture includes all elements of the WAParchitecture related to application specification and execution. To date, the WAEarchitecture is predominately focused on the client–side aspects of WAP’s systemarchitecture, namely items relating to user agents. Such an approach has workedparticularly well with a browser (a class of user agent) model such as that used in theWWW. The Internet and the WWW were the inspiration behind significant elements ofthe WAE specification and consequently, a similar approach is used within the WAE.

ISSUE 1 REVISION 3 Wireless Application Protocol



2–19

Objectives of the WAP Forum� Bring internet content and advanced data services to cellular phones and other

wireless terminals.

� Create a global wireless specification that will work across differing wirelessnetwork technologies.

� Enable the creation of content and applications that scale across a very widerange of bearer networks and device types.

� Embrace and extend existing standards and technology wherever appropriate.

Origin Server

Content

Common GatewayInterface Scripts

CP7_2_08a

Client

WAE User Agent

Encoded Request

Encoders and Decoders

Gateway

Content

Request

Encoded Content

ISSUE 1 REVISION 3GPRS



2–20

GPRSGPRS is a set of new GSM bearer services that provides packet mode transmissionwithin the PLMN and interworks with external networks whilst not preventing the user’soperation of other GSM services.

GPRS will allow the service subscriber to send and receive data in an end–to–end packettransfer mode, without utilising network resources in circuit switched mode. This enablesa more cost effective and efficient use of network resources for applications displayingone or more of the following characteristics:

� Intermittent, bursty data transmissions, where the time between successivetransmissions greatly exceeds the average transfer delay.

� Frequent transmissions of small volumes of data (e.g. less than 500 octets)occurring at a rate of up to several transactions per minute.

� Infrequent transmissions of larger volumes of data (e.g. several kilobytes)occurring at a rate of up to several transactions per hour.

ISSUE 1 REVISION 3 GPRS



2–21

GPRS Network Entities

Frame Relay

TCP/IP Backbone

PDNTo another

PLMN

A

AbisGDS

(Motorola)

Gr

GsGb

Gn

Gn

Gn

Gp Gi

Net103_1_2

MSC

PCU

SGSN

BTS

GGSN

BSC

SGSN

BTSHLR

ISSUE 1 REVISION 3Infrastructure



2–22

InfrastructureAt present, the GSM network is based on circuit switched connections and thus radicalmodifications to the architecture will be required to support the packet switchingtechnology of GPRS. However, the primary and familiar physical characteristics of theair interface will remain largely intact although a series of new GPRS radio channels hasbeen defined.

The most significant addition to the infrastructure will be the GPRS Support Nodes(GSN) which will act “in parallel” with MSCs to supply traffic to the BSS.

Gateway GSN(GGSN)

The GGSN will interface between the BSS and various packet switched networks, (inmuch the same way that an MSC forms an interface between the BSS and the PSTN).The role of GSNs has been likened to that of “routers” in other data networks.

The GGSN can best be compared to carrying out a similar task to that of the GatewayMSC and provides the functionality of the IWF.

Serving GPRSSupport Node(SGSN)

The Serving GPRS Support Node (SGSN) offers very similar functionality to that of theMSC in a GSM network.

Packet ControlUnit (PCU)

The PCU attaches to existing the Base Station Controller (BSC).

The PCU is responsible for all functions of GPRS radio protocols and communicationswith the SGSN.

MSC, HLR andVLR

The MSC and VLR are utilised for initial registration and contacting GPRS MS’s but arenot needed when routing GPRS data. The HLR holds information about the subscriptiondetails and the AUC is required for authentication and ciphering. The EIR can be used forauthenticating MS hardware.

ISSUE 1 REVISION 3 Infrastructure



2–23

GPRS Network Entities

Frame Relay

TCP/IP Backbone

PDNTo another

PLMN

A

AbisGDS

(Motorola)

Gr

GsGb

Gn

Gn

Gn

Gp Gi

Net103_1_2

MSC

PCU

SGSN

BTS

GGSN

BSC

SGSN

BTSHLR

ISSUE 1 REVISION 3GPRS network elements



2–24

GPRS network elements

Gateway GPRSSupport Node(GGSN)

The GGSN is the node that is accessed by the Packet Data Network (PDN) due toappropriate evaluation of the Packet Data Protocol (PDP) address (e.g. X.25 or IPaddress). The GGSN is linked to the external PDNs via the Gi interface or to GPRSnetworks in different Public Land Mobile Networks (PLMN) via the Gp interface. As such,the GGSN is the first point of interconnection. The GGSN may also connect to the HomeLocation Register (HLR) which allows routing information to be passed back down to theGGSN which in turn allows the Packet Data Units (PDU) to be tunnelled towards the MS.With regards to network access, the GGSN can provide message screening functionalityto assist in security as well as providing a means of collecting network data for chargingpurposes.

On the other side of the GGSN, the Gn interface provides the connection towards theServing GPRS Support Node (SGSN). PDUs will be carried on this interface by meansof encapsulation into an IP datagram. This allows both X.25 and IP PDUs to be carriedin the similar formats across the GPRS network.

Serving GPRSSupport Node(SGSN)

The SGSN is the node that is serving the MS and as such, the SGSN deals with bothmobility management and security. The SGSN will establish a PDP context to allowPDUs to be transferred between the MS and the GGSN that the MS is currently utilising.To maximise the efficiency of the connection, data compression techniques may beactivated between the SGSN and the MS.

The SGSN will connect with the MSC/VLR of the GSM network via the Gs interface.This will be used to deal with GPRS/GSM interactions when the same resource is beingutilised by both technologies. The Gd interface provides a connection towards the ShortMessage Service-Centre (SMSC) as the GPRS bearer is able to support SMSPoint–to–Point messages. If an Equipment Identity Register (EIR) is supported in thenetwork, the SGSN will link to it via the Gf interface.

Depending upon routing requirements, the PDUs will pass from the SGSN down to thePacket Control Unit (PCU) which is located at the BSS. This connection is made via theGb interface.

ISSUE 1 REVISION 3 GPRS network elements



2–25

Gateway GPRS Support Node – Functionality� Transport Layer Routing Protocol Support

� PDU Tunnelling

� Screening

� Data/Packet Counting

� Address Mapping, Routing Tables

Serving GPRS Support Node – Functionality� Mobility Management

� Ciphering

� Compression

� GSM Circuit Switched Interactions

� BSS Queue Management

� Data Packet Counting

ISSUE 1 REVISION 3Packet Control Unit (PCU)



2–26

Packet Control Unit (PCU)The new BSS functionality for GPRS mainly resides at the Packet Control Unit (PCU).The PCU includes the handling of frame relay, Network Services Signalling, BSSGPsignalling, routing of signalling messages, Radio Link Control (RLC) and Media AccessControl (MAC) preload and transferring of user data.

User data is routed to the PCU via the CCU uplink from the BTS to the BSC and thenover E1 to the PCU. At the PCU the RLC Blocks are reformulated in Logical Link Control(LLC) frames and forwarded to the SGSN.

BSSGP signalling and NS signalling shall occur between the PCU and the SGSN usingframe relay protocol. There is also signalling between existing functional process at theBSC such as the BSP and the PCU via the E1 Span, as well as between the PCU andChannel Coders.

ISSUE 1 REVISION 3 Packet Control Unit (PCU)



2–27

Packet Control Unit (PCU)

CP07_2_17a

BSC

PCU

MSC

RXCDR

A Interface

A-bis interface

GDS

BTS BTS

SGSN

� ��

ISSUE 1 REVISION 3GPRS Mobile Stations



2–28

GPRS Mobile StationsA GPRS MS can operate in one of three modes of operation. The mode of operation willdepend upon the services that the MS is attached to, i.e., only GPRS or both GSM andGPRS. The three different modes of operation are defined in terms of mobile classesand can be defined as such:–

� Class A – will support simultaneous attach, simultaneous activation, simultaneousmonitor, simultaneous invocation and simultaneous traffic. Thus the subscriberusing a Class A MS can make and/or receive calls on the two servicessimultaneously subject to the QoS requirements.

� Class B – will support simultaneous attach, simultaneous activation, simultaneousmonitor. It will, however, only support limited simultaneous invocation such thatGPRS virtual circuits will not be cleared down due to the presence of circuitswitched traffic. Under such circumstances, the GPRS virtual connection is then“busy or held”. A Class B MS will not support simultaneous traffic. The subscribercan make or receive calls on either of the two services sequentially but notsimultaneously. The selection of the appropriate service is performedautomatically.

� Class C – will support only non–simultaneous attach, i.e. alternate use only. Ifboth services are supported, then a Class C MS can make and/or receive callsfrom only the manually or default selected service. The status of the service notselected is detached or not reachable. In addition, the ability of a Class C MS toreceive and transmit SMS messages is optional.

It should be noted that non–voice only MSs do not have to (but may) support emergencycalls.

ISSUE 1 REVISION 3 GPRS Mobile Stations



2–29

GPRS MS Class Capabilities

CP07_2_18

Class A Class B Class C

User orService Provider

selects

At thesame time Automatically at

different times

Data Voice VoiceVoice DataData

ISSUE 1 REVISION 3GPRS Mobile Stations



2–30



i

Chapter 3

Terrestrial Interfaces

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 3Terrestrial Interfaces i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 3–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the GGSN 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . GPRS Tunnelling Protocol (GTP) 3–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . User Datagram Protocol (UDP) Header 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Transmission Control Protocol (TCP) Header 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Internet Protocol (IP) 3–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the SGSN 3–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Sub–network Dependent Convergence Protocol (SNDCP) 3–10. . . . . . . . . . . . . . . . . . . . . . . .

SNDCP Service Functions 3–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Logical Link Control (LLC) 3–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Base Station System GPRS Protocol (BSSGP) 3–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

BSSGP Virtual Connection Identifier (BVCI) 3–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Frame Relay Operation 3–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv




3–1


� State the GPRS Protocols.

� Explain the functions of the GPRS Protocols.

ISSUE 1 REVISION 3Activity at the GGSN



3–2

Activity at the GGSN

GPRS TunnellingProtocol (GTP)

The GPRS Tunnelling Protocol (GTP) is used between the GPRS Support Nodes(GSN)within the GPRS backbone network. This protocol provides a ’tunnel’ or path, forthe signalling and data transfer procedures necessary for the transfer of multi–protocolpackets.

Two planes are specified for the GTP:

The Signalling Plane – GTP specifies a tunnel control and management protocol thatallows the SGSN to provide GPRS network access for a MS. Signalling is used to create,modify and delete tunnels.

The Transmission Plane – GTP uses the tunnelling mechanism to provide a service forcarrying user data packets. The choice of path is dependent on whether the user data tobe tunnelled required a reliable link or not.

The GTP is only implemented by the GGSN and the SGSN and as such no other entityneed be aware of GTP. In fact, the GPRS MS connected to the SGSN will be unawareof the presence of GTP.

ISSUE 1 REVISION 3 Activity at the GGSN



3–3

GPRS Application Protocols

CPO7_4_1

GSM RF

LLC

SNDCP

IP/X.25

MS

GSM RF

NetworkService

L1 Bis

BSS

L1 Bis

NetworkService

BSSGP

LLC

L1

L2

IP

TCP/UDP

GTP

SGSN

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSN

MAC

Application

RLC

MAC

Relay

RelayRLC BSSGP

SNDCP

Um Gb Gn Gi




3–4

At the GGSN, the next stage is the encapsulation of the T–PDU with either UDP or TCP.Currently, UDP is the only path protocol defined to transfer GTP signalling messages andis the recommended choice for the establishment of a connectionless path forconnectionless T–PDUs. For reliable connection orientated paths, TCP is used forT–PDUs. It should be noted that both UDP and TCP use the services of IP.

User DatagramProtocol (UDP)Header

The UDP Header was discussed earlier and comprises of a Source Port, DestinationPort, Length Indicator and Checksum. With regards to signalling request messages, theUDP Destination Port is set to 3386 which is reserved currently for GTP. The SourcePort will be locally allocated by the sending SGN. For signalling response messages, theDestination Port will be the same as the Source port for the corresponding requestmessage and the Source Port will be set once again to 3386. In the case ofencapsulated T–PDUs in connectionless mode, the UDP Destination Port will be set to3386 and the Source Port will once again be locally allocated.

The signalling message or T–PDU along with the UDP Header is then passed down tothe IP layer where an IP header is added.

TransmissionControl Protocol(TCP) Header

Once again, the TCP Header has already been discussed earlier. In the case of T–PDUs(Transport layer Packet Data Units) being tunnelled across the Gn interface, theDestination Port will be set to 3386 and the Source port will be set locally by the sendingGSN. This, too, will be passed down to the IP Layer where once again, an IP Header willbe added.

Internet Protocol(IP)

In the GPRS Phase 1, IPv4 will be the networking technology upon which GTP tunnellingshall be based. The IP address used for routing purposes will be independent of the”Public” Internet and as such be considered as a GPRS Intranet linking all the GSNs inthe network. Therefore, when encapsulated data is passed down to the IP Layer fromeither UDP or TCP, the source and destination IP addresses will correspond to the IPaddress of the subsequent GSNs to which the data/signalling message should betunnelled. This information is carried in the IP header and routing is determined inaccordance with standard IPv4 practices.




3–5

Internet Protocol (IP) Encapsulation

CPO7_4_2

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSNGn

IPUDP/TCP

GTP PDU

UDP/TCP

GTP PDU

GTP PDU

PDU




3–6

In summary, a packet from an external data network will be encapsulated at the GGSNwith the GTP Header, UDP or TCP Header and IP Header. If the resulting IP datagramis larger than the Maximum Transfer Unit (MTU) on the first link, fragmentation of the IPdatagram will occur. This will be performed by the GGSN. It is desirable that the IPdatagram be no larger than the path MTU value to ensure a quicker and more reliableconnection. If fragmentation does occur, it is the IP Layer of the SGSN that willreassemble the fragments of the initial datagram before passing up the data to eitherTCP or UDP.




3–7

Internet Protocol (IP) Encapsulation

CPO7_4_3

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSNGn

IPUDP/TCP

GTP PDU

UDP/TCP

GTP PDU

GTP PDU

PDU

ISSUE 1 REVISION 3Activity at the SGSN



3–8

Activity at the SGSNData and signalling messages arrive at the SGSN via the Gn interface. The IPdatagrams are collected by the IP Layer and are reassembled if fragmentation hasoccurred either at the GGSN or at any subsequent IP router along the Gn interface. Anyadditional processes are carried out at this layer before the payload is passed up toeither UDP or TCP. The use of IP is indicated in the Type Field in the IP Header and isdependent upon whether a connectionless or connection orientated path is required.

At the UDP/TCP layer, more processes are carried out such as determining thechecksum value before this payload is passed up to GTP. Once again, the exactdestination to which the payload is sent in GTP is determined by the Destination Portaddress.

At the GTP Layer, the GTP Header is stripped off resulting in the PDU being ready foronward transmission across the Gb interface towards the BSS. As such, the PDU canbe said to have been tunnelled across the Gn interface.

To traverse across the Gb interface, the PDU requires further modification. This iscarried out by the Sub–network Dependent Convergence Protocol (SNDCP), the LogicalLink Control (LLC) Protocol and the Base Station System GPRS Protocol (BSSGP)before being carried towards the BSS via a Frame Relay network. Therefore, to explainthe actions of the SGSN, we shall once again discuss the role of the above protocols withregards to a PDU traversing the GPRS network.

ISSUE 1 REVISION 3 Activity at the SGSN



3–9


CPO7_4_4

GSM RF

LLC

SNDCP

IP/X.25

MS

GSM RF

NetworkService

L1 Bis

BSS

L1 Bis

NetworkService

BSSGP

LLC

L1

L2

IP

TCP/UDP

GTP

SGSN

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSN

MAC

Application

RLC

MAC

Relay

RelayRLC BSSGP

SNDCP

Um Gb Gn Gi

ISSUE 1 REVISION 3Sub–network Dependent Convergence Protocol (SNDCP)



3–10

Sub–network Dependent Convergence Protocol (SNDCP)Network layer protocols are intended to be capable of operating over services derivedfrom a wide variety of sub–networks and data links. GPRS supports several networklayer protocols providing protocol transparency for the users of the service. Introductionof new Network Layer protocols will, therefore, be possible without changing any of thelower GPRS protocols. Therefore, all functions related to the transfer of Network LayerProtocol Data Units (N–PDUs) are carried out in a transparent way by the GPRS networkentities – SNDCP.

The set of protocol entities sitting above SNDCP consists of commonly used networkprotocols. These all use the same SNDCP entity, which then performs multiplexing ofdata coming from different sources before being sent via the services, provided by theLLC Layer. The Network Service Access Point Identifier (NSAPI) acts as an index forthe appropriate Packet Data Protocol (PDP) which is using the services of SNDCP. Eachactive NSAPI uses the services provided by the SAPI in the LLC Layer and as suchseveral NSAPIs may be associated with the same SAPI.

ISSUE 1 REVISION 3 Sub–network Dependent Convergence Protocol (SNDCP)



3–11

Sub–network Dependent Convergence Protocol (SNDCP)

CPO7_4_5

Packet DataProtocol

Packet DataProtocol

Packet DataProtocol

SN–PDU

N–PDU

LLC

SNDCP

NSAPI

SAPI

ISSUE 1 REVISION 3SNDCP Service Functions



3–12

SNDCP Service FunctionsThe following functions are performed by SNDCP:

� Transmission and reception of N–PDUs in acknowledged and unacknowledgedLLC mode. In acknowledged mode, the receipt of data shall be confirmed at theLLC layer, and the data shall be transmitted and received in order per NSAPI. Inunacknowledged mode, the receipt of data shall not be confirmed at the SNDCPlayer nor at the LLC layer.

� Transmission and reception between the MS and SGSN of variable–lengthN–PDUs.

� Transmission and reception of N–PDUs between the SGSN and MS according tothe negotiated QoS profile.

� Segmentation and reassemble. The outputs of the compression functions aresegmented to the maximum length of LL–PDU. This is independent of theparticular Network Layer protocol being used.

� Transfer of the minimum amount of data possible between the SGSN and MSthrough compression techniques.

� Compression of redundant protocol control information (e.g. TCP/IP header) at thetransmitting entity and decompression at the receiving entity. Compression may beperformed independently for each QoS delay class and precedence class. Ifseveral network layers use the same QoS delay class and precedence class, thenone common compressor may be used for these network layers.

ISSUE 1 REVISION 3 SNDCP Service Functions



3–13

SNDCP Service Functions

SNDCPHeader

CP07_4_6

ControlCompression

DataCompression

Segmentation

SN–DATA PDU/SN–UNIDATA PDU

SNDCP

Networklayer

SNDCP

LLC LLCFrame

Header Data

Segmented N–PDU

LLC Header SN–DATA PDU/SN–UNIDATA PDU FCS

N–PDU

ISSUE 1 REVISION 3Logical Link Control (LLC)



3–14

Logical Link Control (LLC)The LLC Layer provides a highly reliable logical connection between the SGSN and theMS and as such spans both the Gb and Um interfaces. In addition, the LLC has beendesigned to be independent of the underlying radio interface protocols in order to allowfor the introduction of alternative GPRS radio solutions at a later date.

The Logical Link Control layer supports:

� Service primitives allowing the transfer of SNDCP Protocol Data Units (SN–PDUs)between the Subnetwork Dependent Convergence layer and the Logical LinkControl layer.

� Procedures for transferring LL–PDUs between the MS and SGSN.

� Procedures for unacknowledged point–to–point delivery of LL–PDUs between theMS and the SGSN.

� Procedures for acknowledged, reliable point–to–point delivery of LL–PDUsbetween the MS and SGSN.

� Procedures for point–to–multipoint delivery of LL–PDUs from the SGSN to the MS.

� Procedures for detecting and recovering from lost or corrupted LL–PDUs.

� Procedures for flow control of LL–PDUs between the MS and the SGSN.

� Procedures for ciphering of LL–PDUs. The procedures are applicable to bothunacknowledged and acknowledged LL–PDU delivery.

The layer functions are organised in such a way that ciphering resides immediatelyabove the RLC/MAC layer in the MS and immediately above the BSSGP layer in theSGSN.

ISSUE 1 REVISION 3 Logical Link Control (LLC)



3–15

Logical Link Control (LLC) Frame

CP07_4_7

1 1–36 n#

3 Octets

# Maximum = 1520 octets

AddressField

ControlField Information Field FCS

ISSUE 1 REVISION 3Base Station System GPRS Protocol (BSSGP)



3–16

Base Station System GPRS Protocol (BSSGP)The protocol architecture, which lies between the BSS and the SGSN, is based uponFrame Relay, which utilises virtual circuits allowing data to be multiplexed from severalMSs. Sitting on top of the Frame Relay protocols is another GPRS specific protocolcalled the Base Station System GPRS Protocol (BSSGP).

The primary functions of the BSSGP include the provision of radio–related information,which is to be used by the Radio Link Control (RLC), and Medium Access Control (MAC)functions. In addition, the BSSGP must also provide the functionality to enable twophysically distinct nodes, an SGSN and a BSS, to operate node management controlfunctions.

The figure opposite illustrates the users of BSSGP. Here we can see that it is not onlythe Logical Link Control (LLC) that utilises BSSGP but also GPRS Mobility Management(GMM) and Network Management (NM) at the SGSN.

The functions of GMM deal with paging and radio status requests, whilst the NMfunctions deal with such aspects as flow control and resets.

At the BSS, a Relay (RL) provides the functions for controlling the transfer of LLC framesbetween the RLC/MAC Layer and the BSSGP Layer.

ISSUE 1 REVISION 3 Base Station System GPRS Protocol (BSSGP)



3–17

Base Station System GPRS Protocol (BSSGP) Interfaces

CPO7_4_8

Relay GMM NM NMGMMLLC

BSSGP

Network ServiceNetwork Service

BSSGPRLC/MAC

Service Model in a BSS Service Model in a SGSN

ISSUE 1 REVISION 3BSSGP Virtual Connection Identifier (BVCI)



3–18

BSSGP Virtual Connection Identifier (BVCI)BSSGP Virtual Connections (BVC) provide communication paths between the BSSGPentities at the SGSN and the BSS. Each BVC is used in the transport of the BSSGPPDUs between peer Point–To–Point (PTP) functional entities and peer signallingfunctional entities. A PTP functional entity is responsible for PTP user data transmissionand as such there is one PTP functional entity per cell.

Each BVC is identified by means of a BSSGP Virtual Connection Identifier (BVCI) whichhas end–to–end significance across the Gb interface and as such, each BVCI is uniquebetween two Network Service (NS) entities. At the SGSN, the BVCIs associated withPTP functional entities are dynamically configured where as for signalling functions, theBVCIs are configured statically and set to 0000 hex.

ISSUE 1 REVISION 3 BSSGP Virtual Connection Identifier (BVCI)



3–19

Gb addressing

CP07_4_9

BSS #1

BSS #2

PTPCell 1

PTPCell 2

PTPCell 1

Signalling

Signalling

BVCI=2

BVCI=3

NSEI=1

BVCI=0

BVCI=2

BVCI=0

NSEI=2

NS–VCI=a

NS–VCI=b

NS–VCI=c

NS–VCI=d

NS–VCI=e

NS–VCI=f

DLCI=16

DLCI=137

DLCI=51

DLCI=43

DLCI=16

DLCI=259

Bea

rer

Cha

nnel

= 5

E1

Bea

rer

Cha

nnel

= 6

E1

DLCI=98

DLCI=17

DLCI=16

DLCI=21

DLCI=302

DLCI=511

NS–VCI=a

NS–VCI=b

NS–VCI=e

NS–VCI=c

NS–VCI=d

NS–VCI=f

SGSN

BVCI=2

BVCI=3

BVCI=0

NSEI=1

BVCI=2

BVCI=0

NSEI=2

Framerelaynetwork

Bearer Channel = 1

E1

Bearer Channel = 2

E1

Bearer Channel = 3

E1

Bearer Channel = 4

E1

ISSUE 1 REVISION 3Frame Relay Operation



3–20

Frame Relay OperationFrame Relay provides virtual connections between devices attached to the network, witheach of the virtual circuits being uniquely identified at each frame relay interface by aData Link Connection Identity 2 octet (DLCI). In practice, the frame is relayed on a DLCIto the first Frame Relay Switch and there, a number of processes are carried out:

� Frame Check Sequence (FCS) analysed

� Frame Length checked

� DLCI checked

If any of the above processes are not carried out successfully, the link is refusedotherwise, the DLCI is accepted. The Frame Relay Switch then looks at the routing tableto determine the correct route upon which to relay the frame. The DLCI is then changedto reflect the new DLCI value for the new link. As a result, the FCS, which works acrossthe address as well as the information field, is recalculated.

In the case of GPRS, Permanent Virtual Circuit (PVCs) are used to map the variousinputs at a SGSN to the outputs at the BSS and visa versa.

Circuits between users should be treated as Network Service Virtual Circuits (NS–VC)which have a specific Network Service Virtual Circuits Identify (NS–VCI).

ISSUE 1 REVISION 3 Frame Relay Operation



3–21

Gb addressing

CP07_4_9

BSS #1

BSS #2

PTPCell 1

PTPCell 2

PTPCell 1

Signalling

Signalling

BVCI=2

BVCI=3

NSEI=1

BVCI=0

BVCI=2

BVCI=0

NSEI=2

NS–VCI=a

NS–VCI=b

NS–VCI=c

NS–VCI=d

NS–VCI=e

NS–VCI=f

DLCI=16

DLCI=137

DLCI=51

DLCI=43

DLCI=16

DLCI=259

Bea

rer

Cha

nnel

= 5

E1

Bea

rer

Cha

nnel

= 6

E1

DLCI=98

DLCI=17

DLCI=16

DLCI=21

DLCI=302

DLCI=511

NS–VCI=a

NS–VCI=b

NS–VCI=e

NS–VCI=c

NS–VCI=d

NS–VCI=f

SGSN

BVCI=2

BVCI=3

BVCI=0

NSEI=1

BVCI=2

BVCI=0

NSEI=2

Framerelaynetwork

Bearer Channel = 1

E1

Bearer Channel = 2

E1

Bearer Channel = 3

E1

Bearer Channel = 4

E1

ISSUE 1 REVISION 3Frame Relay Operation



3–22



i

Chapter 4

Air Interface

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 4Air Interface i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 4–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Logical Channels 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Broadcast Control Channel (PBCCH) 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Common Control Channel (PCCCH) 4–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Dedicated Control Channels 4–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Traffic Channels 4–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Allocation of Resources 4–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Release of PDCH 4–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Multiframe Structure for PDCH 4–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Downlink Resource Allocation 4–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Uplink Resource Allocation 4–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Fixed Allocation 4–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Dynamic Allocation 4–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Mobility Managment State Diagram 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Idle to Ready 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ready to Standby 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standby to Ready 4–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Standby to Idle 4–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Ready to Idle 4–18. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mobile Identity 4–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Timing Advance 4–22. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the BSS 4–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Radio Link Control (RLC) Layer 4–24. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Medium Access Control (MAC) Layer 4–26. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

The Physical Layer 4–28. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Channel Coding Schemes 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme CS-1 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 2 (CS-2) 4–30. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 3 (CS-3) 4–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Coding Scheme 4 (CS-4) 4–32. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Activity at the GPRS MS 4–34. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Quality of Service 4–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Precedence Class 4–36. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Delay Class 4–38. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Reliability Class 4–40. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv




4–1


� State the GPRS Logical Channels.

� State the types and explain the Resource Allocation methods.

� Explain how Timing Advance is achieved in the GPRS system.

� State the Coding Schemes and Quality of Service criteria.

ISSUE 1 REVISION 3Logical Channels



4–2

Logical ChannelsA new set of logical channels has been defined for use with GPRS.

PacketBroadcastControl Channel(PBCCH)

The PBCCH broadcasts packet data system information and follows the same predefinedrules for mapping onto physical channels as the BCCH. The existence of the PBCCH isindicated on the BCCH and should it not be allocated then the packet system informationwill be in the BCCH.

Packet CommonControl Channel(PCCCH)

The Packet Common Control Channel (PCCCH)

The PCCCH is very similar in make up to the CCCH and when not allocated in a cell,packet transfer can be initiated by the CCCH.

Packet Random Access Control Channel (PRACH)

The PRACH is uplink only, and is used by an MS to initiate uplink transfer for sendingdata or signalling information. The access burst used on the PRACH is also used toobtain timing advance information.

Packet Paging Channel (PPCH) Downlink only

The PPCH is used to page an MS prior to a MS terminated data transfer. The PPCHuses paging groups to allow for Discontinuous Reception (DRX) and follows exactly thesame predefined rules as is done by the PCH. MS’s in both circuit switching and packetswitching modes can be paged although this is only applicable for GPRS MS’s class Aand B. Further to this an MS engaged in a packet switched transfer can be paged on aPacket Associated Control Channel (PACCH).

Packet Access Grant Channel (PAGCH)

The PAGCH is downlink only and is used during the establishment of packet transfer tosend resource assignment messages. Should the MS be currently involved in a packettransfer then the resource assignment messages can be sent on the PACCH.

Packet Notification Channel (PNCH)

The PNCH is downlink only to send a Point to Multipoint-Multicast (PTM-M) notification toa group of MS’s prior to the PTM-M packet transfer taking place. This notification is inthe form of a resource assignment message. Insert SYS02_1_13b with the addition ofthe GPRS channels below.

ISSUE 1 REVISION 3 Logical Channels



4–3

GSM Control Channels

CPO7_3_01

LOGICALCHANNELS

DEDICATEDCHANNELS

COMMONCHANNELS

TRAFFICCHANNELS

BROADCASTCHANNELS

COMMONCONTROLCHANNELS

DEDICATEDCONTROLCHANNELS

FCCH BCCHSCH AGCHRACHPCH FACCHSACCHSDCCH TCH/HTCH/F

GPRS Specific Logical Channels

CPO7_3_02

LOGICALCHANNELS

DEDICATEDCHANNELS

COMMONCHANNELS

TRAFFICCHANNELS

BROADCASTCHANNELS


PBCCH PPCH PDTCH

Broadcast

PRACH PAGCH PNCHPaging Random

AccessAccessGrant

NotificationPACCH PTCCH

ResourceAssignment

TimingAdvance

DataTraffic

Channel


ISSUE 1 REVISION 3Logical Channels



4–4

PacketDedicatedControl Channels

Packet Associated Control Channel (PACCH)

PACCH conveys signalling information related to an MS, e.g. acknowledgements andPower control information. It also carries resource assignment and reassignmentmessages, comprising the assignment of a capacity for a PDTCH(s) and for furtheroccurrences of PACCH. The PACCH shares resources with the PDTCHs that arecurrently assigned to one MS. An MS that is currently involved in packet transfer can bepaged for circuit switched services on PACCH.

Packet Timing advance Control Channel (PTCCH) (uplink and downlink)(U/D)

� Uplink – Random access bursts are used to allow estimation of timing advance.

� Downlink – Transmits timing advance information to several MSs.

One PTCCH/D is paired with several PTCCH/U’s.

Packet TrafficChannels

Packet Data Traffic Channel (PDTCH).

Used for data transfer and is mapped directly onto one physical channel. Temporarilydedicated to one MS or a group of MSs. One MS may use multiple PDTCHs in parallelfor individual packet transfer. Up to eight PDTCHs, each with different timeslots, can beallocated to one MS at the same time or to a group of MS’s in the case ofPoint-to-Multipoint-Multicast messages (PTM-M).

ISSUE 1 REVISION 3 Logical Channels



4–5

Logical Channel Directions

CPO7_3_03

PBCCH

PTCCH PACCH PDTCH

PRACH PPCH PNCHPAGCH

Packet Broadcast Control Channel (PBCCH)

Packet Common Control Channels (PCCCH)

Packet Dedicated Control Channels Packet Traffic Channel

ISSUE 1 REVISION 3Allocation of Resources



4–6

Allocation of ResourcesA cell supporting GPRS may allocate resources on one or several physical channels inorder to support the GPRS traffic. Those physical channels shared by the GPRS MS’sare taken from a common pool of physical channels available in the cell. This allocationof physical channels to circuit switched services and GPRS is carried out dynamicallyaccording to the ‘capacity on demand’ principles.

The ‘capacity on demand’ principles refer to the fact that PDCH’s need not bepermanently allocated in order to support GPRS and the way in which the networkallocates available resources as required.

Common control signalling that is required by GPRS in the initial phase of packet transferis conveyed on the PCCCH, when allocated, or on the CCCH. This saves on GPRSspecific capacity for the operator. Should the last available PCCCH be allocated then theMS would perform cell re-selection.

At least one PDCH, acting as the master, carries the PCCCH as well as PDTCH andPACCH. Other PDCH’s, acting as slaves, are used for user data transfer and fordedicated signalling.

Release of PDCH

The fast release of PDCH is an important feature to enable the dynamic sharing of thephysical radio resources between packet and circuit switched servics. To enable thisthree PDCH release options are available:

� Wait for all assignments to terminate on that PDCH.

� Individuaklly notify all the users that have assignments on that PDCH.

� Broadcast the notification about de-allocation.

ISSUE 1 REVISION 3 Allocation of Resources



4–7

GPRS Timeslot Configurations

CPO7_3_08

0

1

2

3

4

5

6

7

Example A Example B Example C

BCCH

CARRIER

CARRIER

2BCCH

CARRIER

CARRIER

2BCCH

CARRIER

CARRIER

2

SW

SW

SW

SW

SW

SW

SW

SW

TCH

TCH

TCH

TCH

TCH

TCH

TCH

BCCHSW

SW

SW

RES

RES

RES

RES

RES

TCH

TCH

TCH

TCH

TCH

TCH

TCH

BCCHTCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

TCH

SW

SW

RES

RES

RES

BCCH

ISSUE 1 REVISION 3Multiframe Structure for PDCH



4–8

Multiframe Structure for PDCHThe multiframe structure for PDCH consists of 52 TDMA frames, divided into 12 blocksof 4 frames (radio blocks) and 4 idle frames. This multiframe can be looked at as two 26frame multiframes on the GSM network, numbered from 0 to 51. It has a duration of240ms and 25.5 multiframes are counted as a superframe.

ISSUE 1 REVISION 3 Multiframe Structure for PDCH



4–9

TDMA Frame

CP07_3_5

0 1 2 3 4 5 6 7 0 1 072 3 4 5 6 1 072 3 4 5 6

B0 B1 B2 B3 B4 B5 B6 B7 B8 B9 B10 B11I I

NBNBNBNB

1 072 3 4 5 6

Radio Block

TDMA frame

240ms

NBNB NB

T T

ISSUE 1 REVISION 3Downlink Resource Allocation



4–10

Downlink Resource AllocationDownlink resources are allocated to the MS via the Packet Downlink Assignmentmessage. This message will detail all the timeslots that the MS may receive data on forthis particular transaction.

Each complete data transfer is allocated a Temporary Block Flow (TBF), known by itsidentifier, the Temporary Flow Identifier (TFI). The TFI is part of each Uplink/DownlinkRLC Data Block and is composed of 7 bits in the Uplink and 5 bits in the Downlink.

The TFI for a particular MS is also specified in the Packet Downlink Assignmentmessage.

The MS then has to receive and decode all the RLC/MAC blocks on its allocatedtimeslots to ascertain if the TFI contained in the block is the TFI allocated to the MS.When the MS identifies a block containing its allocated TFI the MS will decode andprocess the data block.

ISSUE 1 REVISION 3 Downlink Resource Allocation



4–11

Downlink RLC data block with MAC header

CP07_3_Downlink

Bit

Payload Type RRBP S/P USFPR TFI FBI

EEM

BSNLength indicator

8 234567 1MAC header

Octet 1Octet 2Octet 3 (optional)...

Length indicator EM Octet M (optional)Octet M+1.

.

.

Octet N-1Octet N(if present)

RLC data

spare spare

.

.

.

Uplink RLC data block with MAC header

CP07_3_Uplink

Bit

Payload Type Countdown Value SITFI TI

EEM

BSNLength indicator

8 234567 1MAC headerOctet 1Octet 2Octet 3 (optional)...

Length indicator EM Octet M (optional)Octet M+1 \Octet M+2 } (optional)

Octet M+4 /Octet M+3 /

Octet M+5..

TLLI

spare spare

.

.

.

R

RLC data .Octet N-1Octet N(if present)

ISSUE 1 REVISION 3Uplink Resource Allocation



4–12

Uplink Resource AllocationAllocation of resources on the Uplink is vital, as the data transmissions from 2 MS couldcollide.

There are 2 methods of implementing Uplink Resource allocation at present.

1. Fixed Allocation of Uplink Resources.

2. Dynamic Allocation of Uplink Resources.

Fixed Allocation

Fixed allocation use the Packet Uplink Assignment message to communicate a detailedfixed uplink resource allocation to the MS. The fixed allocation consists of a start frame,timeslot assignment and blocks assignment. The MS waits until the start frame and thentransmits on radio blocks on those assigned.

This information is passed to the MS in the form of an ALLOCATION_BITMAP, whichrepresents uplink radio blocks, each bit representing one radio block or an entire blockperiod. Each bit indicated whether the mobile station is permitted to transmit during thecorresponding uplink radio block or radio block period.

An MS receiving a fixed allocation can transmit on the uplink without having to monitorthe downlink to see if blocks are free (this is normally indicated by the USF).

If the current allocation is not sufficient, the MS may request additional resources in oneof the assigned uplink blocks. The number of blocks an MS requests in the initial andsubsequent allocation requests can only account for the number of data and controlblocks it intends to send. The MS cannot request additional blocks for the retransmissionof erroneous blocks.

ISSUE 1 REVISION 3 Uplink Resource Allocation



4–13

PDTCH Fixed Allocation

CP07_3_6

B0 B1 IB2 B3 B4 B5 I B8B7B6 B10I B9 IB11

B0 B1 B2 I B3 B4 B5 I B8B7B6 B10I B9 IB11

TS0 TS3TS2TS1 TS7TS6TS5TS4

= MS assigned blocks + timeslots

ISSUE 1 REVISION 3Uplink Resource Allocation



4–14

DynamicAllocation

The dynamic allocation of Uplink resources is based upon the use of the Uplink StateFlag (USF). The USF forms part of each downlink Data or Control Block that is sent.

The USF is transmitted in the downlink to indicate an ‘invitation to transmit’ to mobiles. Amobile is allocated a number of uplink time-slots (shared with other mobiles) and each istold when they may be allowed to transmit. Although up to the maximum 8 time-slotsmay be allocated, this would require the phone to have a duplexer.

The USF has a fixed length of 3 bits, so that up to 7 MS can be distinguished on aparticular timeslot. A MS having multiple timeslots allocated may have different USFsallocated for each timeslot.

A USF value of ’111’ is used to denote that the next uplink block is reserved forPRACH’s.

Once the MS detects its USF in the downlink RLC Data Blick it will transmit on the nextuplink block or the next 4 uplink blocks dependent upon the value of theUSF_GRANULARITY.

The USF_GRANULARITY is also included in the Packet Uplink Assignment. TheUSF_GRANULARITY has two values, ’0’ and ’1’.

If the USF_GRANULARITY is set to ’0’ the MS will transmit on the next uplink blockfollowing the appearance of its USF value.If the USF_GRANULARITY is set to ’1’ the MS will transmit on the next four uplink blocksfollowing the appearance of its USF.

In the diagram opposite two MS’s have been allocated uplink resources dynamically.

MS 1 will look for a USF value of 5 on timeslot 6 and a USF value of 3 on timeslot 7.

MS 2 will look for a USF value of 4 on timeslot 6 and a USF value of 2 on timeslot 7.

Following the appearance of these respective values each MS will transmit on the nextavailable uplink block.

ISSUE 1 REVISION 3 Uplink Resource Allocation



4–15

PDTCHs Dynamic Allocation

CPO7_3_07

5 5 5 4 5 5 4 4

5 5 5 4 4455

3 3 2 2 3 3 2 2

3 3 2 2 3 3 2 2

I I

II

I I

I

I

I I

I

II

I

II

DL

DL

UL

UL

TS6

TS7

FCS

BH Information BCS BH Information BCS BH Information BCS

Information FieldFH

NB NB NB NB

LLC

RLC/MAC

ISSUE 1 REVISION 3GPRS Mobility Managment State Diagram



4–16

GPRS Mobility Managment State DiagramLooking at the state diagram, it can be seen that the model is similar at both the MobileStation (MS) and the Serving GPRS Support Node (SGSN).

Idle to Ready

When moving from an Idle State to a Ready State a mobile must first perform a GPRSAttach. If successful this will make the mobile known to the network, i.e. SGSN. Ifunsuccessful the mobile will fall back to the Idle State.

Following the attach sequence a MM context is said to be active at the MS and theSGSN.

Once in the Ready State, a PDP context may be activated which allows the MS toestablish a packet data session with the associated packet data networks (PDNs). Inparticular this will associate a PDN address within the MS and the GGSN.

With a valid PDP context it is possible to transfer Protocol Data Units (PDUs). Once thetransmission of PDUs has finished then a Ready Timer is started (which starts with adefault value, but may be changed by the SGSN). Both the MS and SGSN should beusing the same value.

Whilst in this state the MS will perform both Cell and Routing Area updates.

Ready toStandby

A move from a Ready State to Standby State will follow the expiry of the Ready Timer ora ‘Force to Standby’ from an MS or SGSN.

Alternatively if a problem is encountered on the RLC/MAC interface, then the MS couldenter the Standby State.

Whilst in this state only Routing Area Updates will be performed.

Standby toReady

Once there are PDUs to transmit/receive the MS and SGSN will enter the Ready State.To enable this a PDP context must have been activated.

ISSUE 1 REVISION 3 GPRS Mobility Managment State Diagram



4–17

GMM State Models for MS and SGSN

CPOy_3_09

GPRSAttach GPRS

Detach

PDUtransmission

Ready timerexpiry orforce tostandby

Idle

Ready

Standby

GPRSAttach

GPRSDetach

or CancelLocation

PDUreception

Ready timer expiry orforce to standby orabnormal RLCcondition

Idle

Ready

Standby

Standby timerexpiry or CancelLocation

Standbytimer expiry

ISSUE 1 REVISION 3GPRS Mobility Managment State Diagram



4–18

Standby to Idle

Once in the Standby State a second timer is started and when this expires or a MAPmessage, ‘Cancel Location’ is received from the HLR, then the return to the Idle State isperformed and the MM context are removed from the MS, SGSN, and GGSN.

Ready to Idle

Either a GPRS detach or a ‘Cancel location’ would change the state from Ready to Idleand in doing so, both MM and PDP contexts would be removed as the MS is no longerconnected to the GPRS network.

ISSUE 1 REVISION 3 GPRS Mobility Managment State Diagram



4–19

GMM State Models for MS and SGSN

CPOy_3_09

GPRSAttach GPRS

Detach

PDUtransmission

Ready timerexpiry orforce tostandby

Idle

Ready

Standby

GPRSAttach

GPRSDetach

or CancelLocation

PDUreception

Ready timer expiry orforce to standby orabnormal RLCcondition

Idle

Ready

Standby

Standby timerexpiry or CancelLocation

Standbytimer expiry

ISSUE 1 REVISION 3Mobile Identity



4–20

Mobile IdentityThe mobile equipment is still identified at the highest level by its own unique IMSI, as thisis used to identify individual records in the location registers.

However, ETSI have defined a new identifier, the P-TMSI (Packet-TMSI) which is knownto the SGSN (which is the supporting node for the mobile equipment in the GPRSnetwork).

The P-TMSI is in turn used by the mobile equipment to derive another value, theTemporary Logical Link Identifier (TLLI) as seen opposite.

The TLLI can be derived from one of three sources:

1. A Local TLLI derived using the P-TMSI from the SGSN, as it is already attached tothe system.

2. A Foreign TLLI as seen by the currently attached SGSN, as this TLLI wasgenerated as a result of a connection to another SGSN and the mobile as movedinto a cell supported by the current (or new) SGSN.

3. A random TLLI could be chosen by the mobile in the absence of a valid PTMSI inorder to determine a TLLI value.

ISSUE 1 REVISION 3 Mobile Identity



4–21

Mobile Identity

CPO7_3_11

Identity

IMSIP-TMSI

TLLITLLI

””

GPRSNetwork

P-TMSI

TLLI

MS

ISSUE 1 REVISION 3Timing Advance



4–22

Timing AdvanceThe MSs initial Timing Advance (TA) is calculated on the Access Burst as for GSM.

The estimated timing advance value is passed to the MS via the Packet ImmediateAssignment. The MS uses this value until continuous timing advance provides a newvalue.

In continuous timing advance the mobile sends in a special access burst in an idle slot forthe network to derive the timing advance. In the downlink the network sends a timingadvance via the Packet Associated Control Channel (PACCH), which is transmittedduring the idle timeslots of the 52 frame multiframe.

Timing Advance Index (TAI) gives the MS the position to send the access burst.

For example TAI = 1 refers to idle timeslot 2. The network will then update the MS timingadvance in the next Timing Advance Message and also the next 3 TA messages. TheMS only has to read the message once.

ISSUE 1 REVISION 3 Timing Advance



4–23

Timing Advance

B0 B1 B2 0 B3 B4 B5 1 B6 B7 B8 2 B9 B10 B11 3

DownlinkB0– B11 = Radio blocks idle bursts are numbered from 0 to 31

TA message 4

Downlink52-multiframe number n+1Uplink

TA message 1

TA=2


TA message 1

TA=4


TA message 2

TA=6

Downlink52-multiframe number n+4Uplink TA=2

TA message 2

TA=8


TA message 3

TA=10


TA message 3

TA=12


TA message 3

TA=14

52-multiframe number n:Uplink TA=0

TA = 1

TA = 3

TA = 5

TA = 7

TA = 9

TA = 11

TA = 13

TA = 15

TA message 1

TA message 1

TA message 2

TA message 2

TA message 3

TA message 3

TA message 4

TA message 4

CPO7_3_12

B0 B1 B2 4 B3 B4 B5 5 B6 B7 B8 6 B9 B10 B11 7

B0 B1 B2 8 B3 B4 B5 9 B6 B7 B8 10 B9 B10 B11 11

B0 B1 B2 12 B3 B4 B5 13 B6 B7 B8 14 B9 B10 B11 15

B0 B1 B2 16 B3 B4 B5 17 B6 B7 B8 18 B9 B10 B11 19

B0 B1 B2 20 B3 B4 B5 21 B6 B7 B8 22 B9 B10 B11 23

B0 B1 B2 24 B3 B4 B5 25 B6 B7 B8 26 B9 B10 B11 27

B0 B1 B2 28 B3 B4 B5 29 B6 B7 B8 30 B9 B10 B11 31

ISSUE 1 REVISION 3Activity at the BSS



4–24

Activity at the BSSData and signalling messages arrive at the BSS via the Gb interface and by using theNetwork Service / Frame Relay. The frames arriving at the Packet Control Unit (PCU)pass through BSSGP where the information and signalling messages are separated intoLLC frames, GPRS Mobility Management (GMM) information and Network Management(NM) information.

With regards to data and signalling messages destined for the GPRS MS, the LLCframes pass through a Relay entity (LLC Relay) before entering the Radio Link Control(RLC) and Medium Access Layer (MAC), respectively.

The RLC/MAC layer provides services for information transfer over the physical layer ofthe GPRS interface. These functions include backward error correction proceduresenabled by selective retransmission of erroneous blocks of data. The MAC functionarbitrates access to the shared medium between a multitude of MSs and the GPRSnetwork.

Radio LinkControl (RLC)Layer

The RLC function is responsible for the transfer of PDUs from the LLC layer and theMAC function, segmentation/re-assembly of LLC PDUs into/from RLC data blocks andbackward error correction.

The RLC data block consists of an RLC Header, and RLC Data Field and spare bits.Each RLC data block may be encoded using any of the available channel codingschemes CS-1, CS-2, CS-3 and CS-4 and as such, will effect the degree ofsegmentation and subsequent re-assembly. If the contents of an LLC PDU do not fill anentire RLC data block, the beginning of the next LLC PDU will be used to fill theremaining bit positions. However, if the LLC PDU was the last in the current transmissionblock, the RLC data block will be completed by the insertion of spare bits.

The structure of the RLC Data Blocks are dependent upon the transmission direction; i.e.Uplink or Downlink.

ISSUE 1 REVISION 3 Activity at the BSS



4–25


CPO7_3_13

GSM RF

LLC

SNDCP

IP/X.25

MS

GSM RF

NetworkService

L1 Bis

BSS

L1 Bis

NetworkService

BSSGP

LLC

L1

L2

IP

TCP/UDP

GTP

SGSN

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSN

MAC

Application

RLC

MAC

Relay

RelayRLC BSSGP

SNDCP

Um Gb Gn Gi

ISSUE 1 REVISION 3Medium Access Control (MAC) Layer



4–26

Medium Access Control (MAC) LayerThe main function of the MAC layer is the control of multiple MSs sharing a commonresource on the GPRS air interface. The RLC data block is passed down to the MAClayer where a MAC header is added.

The format of the MAC header is dependent upon the direction of data transfer. Thefields in the MAC header are:-

USF – Uplink State Flag is used to indicate which MS is allocated the GPRS resource.

S/P – Supplementary/Polling bit is used to indicate whether the RRBP field is active.

RRBP – Relative Reserved Block Period is used to specify that a single uplink block is being used as a Packet Associated Control Channel (PACCH).

Payload Type – defines the type information in the payload area, that is either data or signalling.

SI – Stall Indicator is used to signal whether the transmission has stalled.

Countdown Value – is sent by the mobile (uplink) to the network so that it can calculate the number of radio blocks remaining in the current uplink allocation of resources.

R – Retry bit which indicates whether the MS transmitted the Channel.

ISSUE 1 REVISION 3 Medium Access Control (MAC) Layer



4–27

Medium Access Control (MAC) Layer

PayloadType

CPO7_3_14

PayloadType

Countdown Value SI R

RRBP

RLC/MAC Block

Uplink

RLC Data Block

RLC/MAC Block

RLC/MAC Control Block

Downlink

8 7 6 5 4 3 2 1

S/P USF

8 1234567

SpareRLC Data UnitRLC HeaderMAC Header

MAC Header ControlHeader

RLC/MAC Signalling Information

ISSUE 1 REVISION 3The Physical Layer



4–28

The Physical LayerThe Physical Layer can be subdivided into two layers, the Physical RF Layer and thePhysical Link Layer. The Physical RF Layer performs modulation of the physicalwaveforms and demodulation of the received wave form into a sequence of bits whichare transferred to the Physical Link Layer.

The Physical Link Layer provides the services for information transfer over a physicalchannel between the MS and the GPRS network. Functions at this layer include:

� Forward Error Correction (FEC) coding which allows for the detection andcorrection of transmitted code words and the indication of code words whichcannot be corrected.

� Rectangular interleaving of one radio block over four bursts in consecutive TDMAframes.

� Procedures for detecting physical link congestion.

� Synchronisation procedures in addition to adjusting timing advance parameters.

� Monitoring and evaluation procedures for radio link signal quality.

� Cell selection and re-selection procedures.

� Transmitter power control procedures.

� Battery power conservation procedures such as Discontinuous Reception (DRx).

ISSUE 1 REVISION 3 The Physical Layer



4–29


CPO7_4_1

GSM RF

LLC

SNDCP

IP/X.25

MS

GSM RF

NetworkService

L1 Bis

BSS

L1 Bis

NetworkService

BSSGP

LLC

L1

L2

IP

TCP/UDP

GTP

SGSN

L1

L2

IP

TCP/UDP

GTP

IP/X25

GGSN

MAC

Application

RLC

MAC

Relay

RelayRLC BSSGP

SNDCP

Um Gb Gn Gi

ISSUE 1 REVISION 3Channel Coding Schemes



4–30

Channel Coding SchemesFour different channel coding schemes have been defined for GPRS.

Coding SchemeCS-1

For Coding Scheme 1 (CS-1), 40 bits are used for the Block Check Sequence (BCS) toincrease protection. These and USF (3 bits), Header and Data (181 bits). In addition, 4tail bits are passed through a 1/2 rate convolutional encoder resulting in a ‘protocol’ 456bit payload.

Therefore, when using CS-1, the data rate is equal to:

181bits/20ms

= 9.05kbps

Coding Scheme 2(CS-2)

For Coding Scheme 2 (CS-2) only 16 bits are used for the BCS but in this case, a CRCcode is used. Other differences between CS-2 and CS-1 include the use of a 6 bit USFto increase robustness during transmission over the air interface. Once again 4 tail bitsare added to the sequence prior to passing through a 1/2 rate convoluted encoder. Theresult of this is a bit stream of 588 bits /20ms but this needs to be reduced to 456 bits tobring it in line with GSM burst structures. Therefore, 132 bits are punctured and thissequence is seen in the diagram overleaf. It should be noted that the USF bits (12 bitsafter encoding) are not punctured.

Therefore, when using CS-2, the data rate is equal to:

268 bits/20ms

= 13.4kbps

ISSUE 1 REVISION 3 Channel Coding Schemes



4–31

Coding Scheme CS-1

USF Header and data BCS 224 bits

4 tail bits rate 1/2 convolutional coding

+

456 bits

3 181 40

6

Coding Scheme CS-2

USF Header and data BCS 294 bits

4 tail bits rate 1/2 convolutional coding

588 bits

6 268 16

12

12

456 bits

Puncturing (132 bits) - see below

. . . . . .15 17 18 19 20 21 22 23 587 5881 2 16

Punctured bits

First Last

(Except 12 specific bits)

ISSUE 1 REVISION 3Channel Coding Schemes



4–32


The process used in CS-3 is almost identical to that of CS-2 other than the degree ofpuncturing.

In this case, the Header and Data is made up of 312 bits and after encoding (with USF,BCS and tail bits) the result is 676 bits. This is punctured once again to the 456 bitsrequired by the GSM burst structure. The puncturing sequence used can be seenopposite.

Therefore, when using CS-3, the data rate will be equal to:

312 bits/20ms

= 15.6kbps


For Coding Scheme 4 (CS-4) there is no FEC applied to the data and as such, there ismore capacity for user information. In this case, we see that the BCS is made up of16bits, using a CRC code and the USF has been extended to 12 bits for robustness.Therefore, using this scheme it is possible to carry 428 bits of header and data.

Thus, the data rate for CS-4 is equal to:

428 bits/20ms

= 21.4kbps

ISSUE 1 REVISION 3 Channel Coding Schemes



4–33

Coding Scheme CS-3

CP07_3_CS3

USF BCSHeader and Data

12

4 tail bitsrate 1/2 convolutional coding

338 bits

676 bits

6 312 16

456 bits

12

Puncturing (220 bits)

1 2 15 16 17 21 22 23. . . . . .First Last

Punctured bits

. . . 27 28 29 . . .669 670 671 672673 674 675 676

Coding Scheme CS-4

CP07_3_CS4

USF BCSHeader and Data

12

No Coding

456 bits

456 bits

12 428 16

+

ISSUE 1 REVISION 3Activity at the GPRS MS



4–34

Activity at the GPRS MSAt the GPRS MS, the PDUs pass through the protocol stack in the reverse order. Thefour consecutive air interface bursts are re-assembled and passed to the RLC/MACLayer. Once all the RLC data blocks for a particular LLC PDU have been received, theLLC frame is re-assembled and passed up to the LLC Layer. Here, the FCS is calculatedand any re-transmissions are activated if necessary, otherwise the payload area ispassed up to the SNDCP layer.

ISSUE 1 REVISION 3 Activity at the GPRS MS



4–35

Activity at the GPRS MS

CP07_3_18

GSM RF

MAC

RLC

LLC

SNDCP

IP/X.25

Application

Burst Burst Burst Burst


MACRLC

RLC DATA

RLC

RLC DATA

Segmented / re-assembly

PDU

Segmented PDU FCSSNDCPLLC

Segmented PDUSNDCP

ISSUE 1 REVISION 3Quality of Service



4–36

Quality of ServiceA Quality of Service (QoS) profile is associated with each PDP context and is consideredto be a single parameter with multiple data transfer attributes. These are defined as:

� Precedence Class

� Delay Class

� Reliability Class

� Peak Throughput Class

� Mean Throughput Class

There are many possible QoS profiles defined by these various attributes and as such, aPLMN may only support a limited number.

During the QoS profile negotiation, it is possible for an MS request a value for each of theQoS attributes, including the HLR stored subscribed default values.

Quality of service parameters are usually negotiated at subscription or during call set-up.

The network will negotiate each attribute to a level that is in accordance with theavailable GPRS resources.

PrecedenceClass

The Service Precedence indicates the relative importance of maintaining the servicecommitments under abnormal conditions such as congestion or limited resources. ThePrecedence Class defines 3 different levels: High, Normal and Low.

ISSUE 1 REVISION 3 Quality of Service



4–37

QoS Profile

Precedence Class - High/Normal/Low

Delay - 4 Delay Classes

Reliability Defined - 5 Classes

Throughput - Peak & Mean

ISSUE 1 REVISION 3Delay Class



4–38

Delay ClassAlthough GPRS is not defined as a ‘store and forward’ system, it does have inherentdelays within its equipment and the supporting protocols. The amount by which SDUsmay be delayed in the network is specified as one of four classes as shown in the figureopposite.

The delays specified do include the following:-

� radio channel access delay (uplink or downlink)

� radio channel transit delay (uplink/downlink)

� GPRS–network delay (multiple hops)

But is NOT inclusive of external network delays.

Whilst the mean transfer delay is specified for the different classes, a 95-percentile delayis also specified, which is the maximum time delay that 95-percent of SDUs will bedelivered across the interface (as opposed to specifying a time delay for 100%transmission).

Delay is measured from:

� the Gi interface for the fixed network

and/or

� the R interface associated with a MS

ISSUE 1 REVISION 3 Delay Class



4–39

Delay Class

CP07_3_19

Delay (maximum values)SDU size: 128 octets SDU size: 1024 octets

Delay Class

1. (Predicitive)

4. (Best Effort)

3. (Predicitive)

2. (Predicitive)

Unspecified

95 percentileDelay (sec)

<375

<75

<7

Mean TransferDelay (sec)

<75

<15

<2

95 percentileDelay (sec)

<250

<25

<1.5

Mean TransferDelay (sec)

<0.5

<50

<5

ISSUE 1 REVISION 3Reliability Class



4–40

Reliability ClassData reliability is defined in terms of residual error rates for the following cases:

� Probability of data loss

� Probability of data delivered out of sequence

� Probability of duplicate data delivery

� Probability of corrupt data

The Reliability Class specifies the requirements of the various network protocol layers ofGTP, LLC and RLC. The transmissin modes associated with these layers are used todefine the 5 Reliability Classes.

ISSUE 1 REVISION 3 Reliability Class



4–41

Reliability Class

CP07_3_20

ReliabilityClass

Traffic TypeRLC BlockMode

LLC DataLLC FrameMode

GTP Mode

1

2

3

4

5

Acknowledged

Unacknowledged

Unacknowledged

Unacknowledged

Unacknowledged

Acknowledged

Acknowledged

Unacknowledged

Unacknowledged

Unacknowledged

Protected

Unprotected

Protected

Protected

Protected

Acknowledged

Acknowledged

Acknowledged

Unacknowledged

Unacknowledged

Non real-time traffic, error-sensitive application that cannotcope with data loss.

Non real-time traffic, error-sensitive application that can copewith infrequent data loss.

Non real-time traffic, error-sensitive application that can copewith data loss, GMM/SM and SMS.

Real-time traffic, error-sensitiveapplication that can cope withdata loss.

Real-time traffic, error non-sensitive application that cancope with data loss.

Note: For real-time traffic, the QoS profile also requires appropriate settings for delay and throughput




4–42

ISSUE 1 REVISION 3 Reliability Class



4–43

Peak and Mean

CPO7_3_21

123456789

8 kb/s16 kb/s32 kb/s64 kb/s128 kb/s256 kb/s512 kb/s1,024 Mb/s2,048 Mb/s

Currently supportedby GPRS

UMTS

123456789

101112131415161718

31

0.22 bits/s0.44 bits/1.11 bits/s2.22 bits/s4.4 bits/s11.1 bits/s22.2 bits/s44 bits/s111 bits/s222 bits/s440 bits/s1.11 kb2.22 kb4.4 kb11.1 kb22.2 kb44 kb111kb/s

Best effort

+ 1 extra called

Peak

Mean




4–44



i

Chapter 5

GPRS Signalling

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 5GPRS Signalling i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 5–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Attach 5–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

GPRS Detach 5–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

PDP Context Activation 5–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . MS PDP Context Activation 5–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Network-Requested PDP Context Activation 5–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Paging for GPRS Downlink Transfer 5–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Transfer – MS Originated 5–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Packet Transfer – MS Terminated 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Packet Paging 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Downlink Packet Transfer 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Release of the Resources 5–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv




5–1


� Explain the GPRS Attach/Detach signalling.

� Explain the GPRS Paging signalling for downlink transfer.

� Explain the GPRS PDP Context activation procedure.

� Explain the GPRS MS Packet transfer procedure.

ISSUE 1 REVISION 3GPRS Attach



5–2

GPRS AttachThe procedure as shown opposite details a combined GPRS and IMSI attach. Takingeach state in turn:

1. The MS initiates the procedure by issuing an ‘Attach Request’

2. The New SGSN sees from the RAI sent by the MS that it was previously attachedto the Old SGSN, therefore the New SGSN sends an ‘Identity Request’ messageto the Old SGSN. The response back from the Old SGSN will include the IMSIand Authentication Triplets.

3. If the MS is unknown to the New and Old SGSNs, then an ‘Identity Request’ issent, and the response should contain its IMSI.

4. Authentication and ciphering procedures may be initiated to ensure MS and datasecurity.

5. A further check can be made of the MS against its IMEI.

6. If the SGSN has changed since the MNS was last attached to the network, theRouting Area (RA) update is needed:

a. The SGSN sends an ‘Update Location’ to the HLR.

b. The HLR send ‘Cancel Locatoin’ to Old SGSN.

c. The Old SGSN acknowledges before removing Mobility Managmenet (MM)and PDP contexts.

d. The HLR saends ‘Inserts Subscriber Information’ to the New SGSN.

e. The New SGSN acknowledges and creates a new MM context.

f. HLR updates its own records and returns an akcnowledgement to the New SGSN.

7. The VLR is updated if the Gs interface is installed.

a. The SGSN sends a ‘Location Updating Request’ message to the VLR.

b. If the LA update is inter-MSC:

� The new VLR sends ‘Update Location’ to the HLR.

� The HLR sends a ‘Cancel Location’ to the old VLR.

� The old VLR acknowledges with ‘Canel Location Ack’.

� The HLR sends ‘Insert Subscriber Data’ to the new VLR.

� The VLR acknowledges with ‘Insert Subscription Data Ack’.

c. After finishing the inter-MSC location update procedures, the HLR responds with ‘Update Location Ack’ to the new VLR.

d. The VLR responds with ‘Location Updating Accept’ to the SGSN.

8. The SGSN sends an ‘Attach Accept’ to the MS.

9. If P-TMSI or VLR TMSI was changed, the MS acknowledges the received TMSI(s)with ‘Attach Complete’.

10. If VLR TMSI was changed, the SGSN confirms the VLR TMSI re-allocation bysending ‘TMSI Reallocatoin Complete to the VLR.

11. If the ‘Attach Request’ cannot be accepted, the SGSN returns an ‘Attach Reject’message to the MS.

ISSUE 1 REVISION 3 GPRS Attach



5–3

Attach

CP07_5_1

MS BSS Old SGSN GGSN EIRNew

MSC/VLR HLROld

MSC/VLR1. Attach Request

2. Identification Request

2. Identification Response

3. Identity Request

3. Identity Response4. Authentication

5. IMEI Check

6a. Update Location

6b. Cancel Location

6c. Cancel Location Ack

6e. Insert Subscriber Data Ack6f. Update Location Ack

7a. Location Updating Request

8. Attach Accept

9. Attach Complete

7h. Location Updating Accept

10. TMSI Reallocation Complete

7b. Update Location

7c. Cancel Location Ack

7d. Cancel Location Ack

7e. Insert Subscriber Data

7f. Insert Subscriber Data Ack7g. Update Location Ack

6d. Insert Subscriber Data

New SGSN

ISSUE 1 REVISION 3GPRS Detach



5–4

GPRS DetachWith respect to the diagrams shown opposite we should consider the three defineddetach procedures.

The top diagram on the opposite page details the Detach procedure that is initiated bythe MS.

1. The MS initiates by sending Detach Request

2. If GPRS detach then the PDP context needs to be deleted in the GGSN.

3. If IMSI detach, the SGSN sends IMSI detach to the VLR.

4. If the MS wants to remain IMSI attached and is doing a GPRS detach, the SGSNsends a ‘GPRS Detach’ indication message to the VLR. The VLR removes theassociation with the SGSN and handles paging and locatin updating without goingvia the SGSN.

5. If the Switch Off parameter indicated that the MS was being switched off, then the‘Detach Accept’ is not sent.

If the detach is initiated by the SGSN, then the sequence is similar to that above, exceptthat the initial message detailed in 1 above is started by the SGSN. Stages 2 and 4above are used as shown in the middle diagram on the opposite page.

The detach sequence could be started by the HLR as shown in bottom diagram on theoppsite page, by the use of a ‘Cancel Location’ MAP message. Following the ‘CancelLocation’ message, the procedure is much the same as for the SGSN initiated Detachprocedure.

ISSUE 1 REVISION 3 GPRS Detach



5–5

Detach

CP07_5_2

SGSN GGSN MSC/VLR HLR

5. Detach Accept

1. Detach Request

2. Delete PDP Context Request

2. Delete PDP Context Response

3. IMSI Detach Indication

4. GPRS Detach Indication

SGSNMS BSS GGSN MSC/VLR HLR

4. Detach Accept

1. Detach Request



3. IMSI Detach Indication

SGSNBSS GGSN MSC/VLR HLR

2. Detach Request


4. GPRS Detach Indication

1. Cancel Location

6. Cancel Location Ack


5. Detach Accept

BSSMS

MS

ISSUE 1 REVISION 3PDP Context Activation



5–6

PDP Context Activation

MS PDP ContextActivation

1. The MS sends an ‘Activate PDP Context Request’ message to the SGSN. TheMS uses the PDP Address field in this message to indicate whether it requires theuse of a static PDP address or whether it requires the use of a dynamic PDPaddress. The MS leaves PDP address empty to request a dynamic PDP address.The MS may use the Access Point Name field to select a reference point to acertain external network. Access Point Name is a logical name referring to theexternal packet data network that the subscriber wishes to connect to.

2. Security functions may be executed. The Security function:

Guards against unauthorised GPRS service usage (authentication and servicerequest validation)

Provides user identity confidentiality (temporary identifiction and ciphering)

Provides user data confidentiality (ciphering)

3. The SGSN validates the ‘Activate PDP Context Request’.

If no GGSN address can be derived then the SGSN rejects the PDP contextactivation request.

If a GGSN address can be derived, the SGSN creates a TID for the requestedPDP context by combining the IMSI stored in the MM context with the NSAPIreceived from the MS. If the MS requests a dynamic address, then the SGSN letsa GGSN allocate the dynamic address. The SGSN sends a ‘Create PDP ContextRequest’ message to the affected GGSN.

The GGSN creates a new entry in its PDP context table. The new entry allows theGGSN to route PDP PDUs between the SGSN and the external PDP network. TheGGSN then returns a ‘Create PDP Context Response’ message to the SGSN. The‘Create PDP Context’ messages are sent over the GPRS backbone network.

4. The SGSN inserts the NSAPI along with the GGSN address in its PDP context. Ifthe MS has requested a dynamic address, the PDP address received from theGGSN is inserted in the PDP context. The SGSN selects a Radio Priority Levelbased on QoS Negotiated, and returns an ‘Activate PDP Context Accept’ messageto the MS. The SGSN is now able to route PDP PDUs between the GGSN and theMS.

ISSUE 1 REVISION 3 PDP Context Activation



5–7

MS PDP Context Activation

CP07_5_4

MS SGSN GGSN

1. Activate PDP Context

3. Create PDP Context

2. Security Functions

4. Activate PDP Context

3. Create PDP Context

Request

Accept

Request

Response

ISSUE 1 REVISION 3Network-Requested PDP Context Activation



5–8

Network-Requested PDP Context ActivationThis procedure allows the GGSN to initiate the activation of a PDP context. Whenreceiving a PDP PDU the GGSN checks if a PDP context is established for that PDPaddress. If no PDP context has been previously established the GGSN may try to deliverthe PDP PDU by initiating this procedure. To support Network-Requested PDP ContextActivation the GGSN has to have static PDP information about the PDP address.

The network operator may implement the following techniques to prevent unnecessaryenquires to the HLR:

� Implementation of the Mobile station Not Reachable for GPRS flag (MNRG)technique in GGSN, SGSN, and HLR that will prevent the GGSN from trying tocontact the MS when it’s switched off or out of coverage area.

� The GGSN may reject or discard PDP PDU’s as a result of previous unsuccessfuldelivery attempts.

� The GGSN may store the address of the SGSN with which the GGSN establishedthe last PDP context. This would prevent an enquiry to the HLR.

The Successful Network-Requested PDP Context Activation is illustrated on theopposing page and the steps are as follows:

1. When receiving a PDP PDU the GGSN determines if the Network-Requested PDPContext Activation procedure has to be initiated. The GGSN may store subsequentPDU’s received for the same PDP address.

2. The GGSN may send a ‘Send Routeing Information for GPRS’ message to theHLR. If the HLR determines that the request can be served, it acknowledges themessage to the GGSN.

3. If the SGSN address is present the GGSN sends a ‘PDU Notification Request’message to the SGSN indicated by the HLR. Otherwise, the GGSN sets theMNRG flag for that MS. The SGSN returns a ‘PDU Notification Response’message to the GGSN in order to acknowledge that it shall request the MS toactivate the PDP context indicated with PDP Address.

4. The SGSN sends a ‘Request PDP Context Activation’ message to request the MSto activate the indicated PDP context.

5. The PDP context is activated with the PDP Context Activation procedure,described earlier.

ISSUE 1 REVISION 3 Network-Requested PDP Context Activation



5–9

Network-Requested PDP Context Activation

CP07_5_6

MS SGSN GGSN

1. PDP PDU

2. Send Routing Info

2. Send Routing Info

for GPRS

4. Request PDP

for GPRS Ack

HLR

Context Activation

3. PDU Notification Request

3. PDU Notification Response

5. PDP Context Activation Procedure

ISSUE 1 REVISION 3Paging for GPRS Downlink Transfer



5–10

Paging for GPRS Downlink TransferAn MS has to be paged by the SGSN before a downlink transfer can occur. The pagingprocess is shown opposite and detailed below:

1. The SGSN receives Protocol Data Units (PDU’s) for an MS from the network andpages the MS.

2. The SGSN sends a ‘BSSGP Paging Request’ to the BSS serving the MS.

3. The BSS pages the MS with one ‘Paging Request’ message in each cell belongingto the addressed routeing area,

4. Upon receipt of the paging message, the MS shall respond with either any singlevalid LLC frame (e.g., a Receive Ready or Information frame) that implicitly isinterpreted as a page response message by the SGSN. When responding, the MSchanges MM state to READY.

5. Upon reception of the LLC frame, the BSS adds an identifier of the cell and sendsthe LLC frame to the SGSN. The SGSN shall then consider the LLC frame to bean implicit paging response message and stop the paging response timer.

ISSUE 1 REVISION 3 Paging for GPRS Downlink Transfer



5–11

GPRS Paging Area

CP07_5_3

MS BSS SGSN

1. PDP PDU

2. Paging Request

3. GPRS Page Request

4. Any LLC Frame

5. Any LLC Frame

ISSUE 1 REVISION 3Packet Transfer – MS Originated



5–12

Packet Transfer – MS OriginatedAn MS initiates a packet transfer by making a Packet Channel Request on PRACH orRACK The network responds on PAGCH or AGCH respectively. It is possible to use oneor two phase packet access method.

In the one phase access, the Packet Channel Request is responded by the network withthe Packet Immediate Assignment reserving the resources on PDCH(s) for uplinktransfer of a number of Radio blocks. The reservation is done accordingly to theinformation about the requested resources that is comprised in the Packet ChannelRequest. On RACH, there is only one cause value available for denoting GPRS and thenetwork can assign uplink resources on 1 or 2 PDCH’s. On PRACH, the Packet ChannelRequest may contain more adequate information about the requested resources and,consequently, uplink resources on one or several PDCH’s can be assigned by using thePacket Immediate Assignment message.

In the two phase access, the Packet Channel Request is responded with the PacketImmediate Assignment which reserves the uplink resources for transmitting the PacketResource Request. The Packet Resource Request message carries the completedescription of the requested resources for the uplink transfer. Thereafter, the networkresponds with the Packet Resource Assignment reserving resources for the uplinktransfer.

The ‘Packet Immediate Assignment’ and the ‘Packet Resource Assignment’ messagesinclude Timing Advance (TA) and Power Control (PC) information.

If there is no response to the ‘Packet Channel Request’ within predefined time period, theMS makes a retry after a random backoff time.

The ‘Packet Uplink Assignment’ message includes the list of PDCH’s and thecorresponding USF value for a particular MS. A unique TFI is also allocated and isincluded in each RLC data and control block relating to that TBF. The MS monitors theUSF’s on the allocated PDCH’s and transmits Radio Blocks on those, which currentlybear the USF value reserved for use by that particular MS.

Because each Radio Block includes an identifier (TFI), all received Radio Blocks arecorrectly associated with a particular LLC frame and a particular MS, which makes theprotocol highly robust. Therefore, by altering the state of the USF, different PDCH’s canbe ‘opened’ or ‘closed’ dynamically for certain MS’s thus providing a flexible reservationmechanism.

The channel reservation algorithm can also be implemented on an assignment basisallowing individual MS’s to transmit for a predetermined amount of time withoutinterruptions.

The MS may also be able to use the uplink resources for as long as there is queued datasitting above on the RLC/MAC Layer. This can comprise of a number of LLC frames.

ISSUE 1 REVISION 3 Packet Transfer – MS Originated



5–13

MS originated packet transfer

CP07_5_7

PACKET CHANNEL REQUEST (PRACH or RACH)

IMMEDIATE ASSIGNMENT (PAGCH or AGCH)

PACKET RESOURCE REQUEST (PACCH)

PACKET RESOURCE ASSIGNMENT (PACCH)

NetworkMS

ISSUE 1 REVISION 3Packet Transfer – MS Terminated



5–14

Packet Transfer – MS Terminated

Packet Paging

The Network initiates packet transfer to an MS that is in Standby state by sending a‘Packet Paging Request’ on the downlink PPCH or PCH. The MS responds to the‘Packet Paging Request’ by initiating a procedure for page response. The RLC/MAC‘Packet Paging Response’ message contains TLLI, as well as a complete LLC frameincluding also TLLI. After the ‘Packet Paging Response’, the mobility management stateof the MS is Ready.

Downlink PacketTransfer

Transmission of a packet to an MS in the Ready state is initiated by the Network usingthe ‘Packet Resource Assignment’ message. In case there is PCCCH allocated in thecell, the ‘Packet Resource Assignment’ is transmitted on PAGCH. In case there is noPCCCH allocated in the cell, the ‘Packet Resource Assignment’ is transmitted on AGCH.The ‘Packet Resource Assignment’ message includes the list of PDCH(s) that will beused for downlink transfer as well as the PDCH carrying the PACCH. The TimingAdvance and Power Control information is also included, if available. Otherwise, the MSmay be requested to respond with an Access Burst.

Multiplexing the Radio blocks destined for different MS’s on the same PDCH downlink isenabled with an identifier, e.g. TFI, included in each Radio Block. The interruption of datatransmission to one MS is possible. The network sends the Radio blocks belonging toone Temporary Block Flow on downlink on the assigned downlink channels.

The sending of ‘Packet Ack/Nack’ is obtained by the occasional network initiated pollingof the MS. The MS sends the ‘Packet Ack/Nack’ message in a reserved Radio Block thatis allocated together with polling. Unassigned USF value is used in the downlink RadioBlock that corresponds to the reserved uplink Radio blocks. Further, if the MS wants tosend some additional signalling or uplink data, it may be indicated in the ‘PacketAck/Nack’ message.

Release of theResources

The release of the resources is initiated by the network by terminating the downlinktransfer and polling the MS for a final ‘Packet Ack/Nack’.

It is possible for the network to change the current downlink assignment. The first way toobtain that would be to terminate the current Temporary Block Flow, and after the MSstarts to monitor the PCCCH, initiate a new one with a new assignment. The secondmethod would be to explicitly change the downlink assignment by using the ‘PacketResource Reassignment’ which then has to be acknowledged by the MS in an immediatereserved block period on the uplink.

The handling of TFI and USF is steered with the same timer that runs on both the MSand the network side after the last RLC Data Block is sent to the MS. When it expires,the current

assignment becomes invalid for the MS and both USF and TFI can be reused by thenetwork.

Further, USF and TFI may be reused already upon the reception of the final ‘PacketAck/Nack’ from the MS.

ISSUE 1 REVISION 3 Packet Transfer – MS Terminated



5–15

MS terminated packet transfer

CP07_5_8

PACKET PAGING REQUEST (PPCH or PCH)

PACKET CHANNEL REQUEST (RACH or PRACH)

PACKET IMMEDIATE ASSIGNMENT (PAGCH or AGCH)

UPLINK TBF – LLC FRAME (PACCH)

MS NetworkPAGING

CP07_5_9

PACKET RESOURCE ASSIGNMENT

MS NetworkRESOURCE

PACCH

AGCHPAGCH

ASSIGNMENT

CP07_5_10

DATA BLOCK

MS NetworkDATA

Temporary Packet Ack/Nack

DATA BLOCK (polling)

DATA BLOCK

DATA BLOCK

DATA BLOCK

TRANSFER

ISSUE 1 REVISION 3Packet Transfer – MS Terminated



5–16



i

Chapter 6

Future Enhancements

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Chapter 6Future Enhancements i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Objectives 6–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Mobile Evolution 6–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

HSCSD 6–4. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Enhanced General Packet Radio Service (E–GPRS) 6–6. . . . . . . . . . . . . . . . . . . . . . . . . . . .

Enhanced Data Rates for GSM Evolution (EDGE) 6–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UMTS 6–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

User Benefits of UMTS 6–14. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

UMTS Future Vision 6–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv




6–1


� Explain the concept of HSCSD.

� Explain the concept of E–GPRS and EDGE.

� Explain the benefits of UMTS and how they will be introduced.

ISSUE 1 REVISION 3Mobile Evolution



6–2

Mobile EvolutionUMTS is an ETSI term for a Third Generation (3G) mobile telecommunication service.Over recent years, mobile telephony evolutions have become known as:

First Generation

In the early 1980s the First Generation were the Worlds first public mobile telephoneservices such as AMPS (US), TACS (UK) and NMT (Scandinavia). These systems wereanalogue, provided national coverage (though from complete in most cases) and offeredlimited services.

Second Generation

GSM is by far the World’s primary Second Generation system. Designed by a joint effortfrom manufacturers, regulators and service suppliers from many (European) countries,GSM became a European and then a global standard. CDMA systems now under thecollective term of cdmaOne are the other major Second Generation technology. Globally,arguments about which was superior became largely academic because GSM wasdeployed first (early 1990s) and rapidly gained universal acceptance (with the exceptionof the US and Japan). CDMA has been launched more recently (mid 1990s) and hasshown remarkable uptake and growth. In late 1998 there are an estimated 12 millionCDMA users and over a 100 million GSM users.

Second Generation Systems offer:

� Open standards (arguable for CDMA)

� Digital technology

� (near) National coverage and roaming

� Voice and data (limited rates)

� Supplementary Services

Third Generation

The World’s leading telecommunication authorities such as the InternationalTelecommunications Union (ITU), ETSI and others are formulating specifications for thenext generation of mobile telecommunication devices and networks. Within ETSI thisnetwork is known as the Universal Mobile Telecommunication System – UMTS and isdata focused.

ISSUE 1 REVISION 3 Mobile Evolution



6–3

Mobile Evolution

CP07_6_1

2G

3G

Packet dataSupport

GSMOperator

GSM 900GSM 1800

GPRS EDGE

UMTS

ISSUE 1 REVISION 3HSCSD



6–4

HSCSDIt is intended that HSCSD will use the 14.4kbps channel coding option and that it willadditionally use multiple timeslots. To see how this might operate requires a basicknowledge of the physical structure of a traffic channel on the Air interface.

The uplink and downlink of a GSM traffic channel take place on different frequencies.Also the uplink and downlink timeslots occur at different times in the 8 time–slot frame.Additionally when engaged in a traffic channel a GSM mobile station must constantly bemonitoring downlink power levels from neighbouring cells as part of the handoverprocess. Over an 8 time–slot frame therefore a mobile will:

� Receive a downlink burst

� Transmit an uplink burst

� Monitor a downlink transmission from a neighbouring cell

2 Timeslots

One restriction that HSCSD places upon multiple timeslot links is that the time–slotsallocated must be consecutive.

As can be seen from the diagram the use of two timeslots is relatively simple toimplement. The mobile is still able to run through its standard routine of receive,transmit, monitor a neighbour within an 8 time–slot frame. With 3 or more time–slotsbeing used there is an overlap between the receive and transmit times andimplementation of this involves substantial hardware changes in the mobile station., i.e.the use of a RF duplexor. (at first sight it looks as if there is no overlap when using 3time–slots but there is due to the timing advance applied to the uplink).

ISSUE 1 REVISION 3 HSCSD



6–5

HSCSD

CP07_6_2

Mobile Rx

Mobile Tx

Data Rate – 28.8 kbps

0 765432107654321

0 765432107654321

Measurea

Neighbour

Measurea

Neighbour

ISSUE 1 REVISION 3Enhanced General Packet Radio Service (E–GPRS)



6–6

Enhanced General Packet Radio Service (E–GPRS)It is proposed that EGPRS will offer eight additional coding schemes. The lower layers ofthe user data plane, which has been specifically designed for GPRS operation isreflected in the protocol, stack comprising Physical, RLC/MAC and LLC layers. While theLLC layer can be used without modifications when EDGE functionality is introduced, it isnecessary to modify the RLC/MAC layer to support features such as efficient multiplexingand link adaptation. The basic modifications needed for EDGE consider the form of thedata blocks that are being transferred across the radio interface. For EGPRS, severalcombinations of interleaving and coding have been proposed where as in the currentGPRS proposals, the interleaving depth is set to four bursts.

Link adaptation offers mechanisms for choosing the best modulation and codingalternative for the current radio link. In GPRS, only the coding scheme can be alteredbetween two consecutive LLC frames however, with EGPRS a refined link adaptationconcept can be utilised which allows both coding and modulation schemes to be changedto suit the given radio link.

In addition, link adaptation should allow seamless switching between the two modulationschemes to such an extent that in EGPRS, the Uplink State Flag (USF) information canbe modulated using B–O–QAM and the user data by Q–O–QAM. B–O–QAM is usedhere for the broadcast purposes and facilitates the characteristics of being robust andtherefore available in the whole GSM coverage area.

Six coding schemes have been specified for 8PSK with regards E–GPRS and these canbe seen opposite. It is assumed that each communication link will be able to choose themodulation and coding combination that achieves the highest throughput for thatparticular link quality. For example, users with a low C/I ratio will be allowed to perform alink adaptation towards GMSK as opposed to 8PSK. This link adaptation betweenGMSK and 8PSK should be seamless since both modulation schemes utilise the samesymbol rate of 270.833ksps.

ISSUE 1 REVISION 3 Enhanced General Packet Radio Service (E–GPRS)



6–7

Enhanced General Packet Radio Service (E–GPRS)

CP07_6_3

Service Name

EGPRS PCS–1

EGPRS PCS–6

EGPRS PCS–5

EGPRS PCS–4

EGPRS PCS–3

EGPRS PCS–2

Code Rate

0.326

1.00

0.829

0.756

0.596

0.496

Modulation

8PSK

8PSK

8PSK

8PSK

8PSK

8PSK

Gross Rate

69.2kbp

69.2kbp

69.2kbp

69.2kbp

69.2kbp

69.2kbp

RadioInterface Rate*

22.8kbps

69.2kbps

57.35kbps

51.6kbps

41.25kbps

34.3kbps

* The ratio interface rate includes signalling overhead in the RLC/MAC layer

ISSUE 1 REVISION 3Enhanced Data Rates for GSM Evolution (EDGE)



6–8

Enhanced Data Rates for GSM Evolution (EDGE)Enhanced Data Rates for GSM Evolution (EDGE) is a proposed modification to themodulation scheme utilised by GSM (i.e. Gaussian Minimum Shift Keying). This changewill drastically increase the bit rates available to end users for the purpose of datatransfer. It is envisaged that the enhanced modulation techniques will make it possible tomaintain a good quality link by automatically adapting to the radio interference conditionsand thereby provide the highest possible rate. The exact implementation and technicaldetails are still being discussed in various ETSI feasibility studies but there are certainfactors that one can almost assume to be near completion.

Two additional modulation schemes have been proposed and these are QuaternaryOffset Quadrature Amplitude Modulation (Q–O–QAM) and Binary Offset QuadratureAmplitude Modulation (B–O–QAM). These two new modulation schemes will both resultin symbol rates of 361.111 kbps but Q–O–QAM will offer a higher bit rate as it supports 2bits / symbol.

Wherever possible, EDGE adopts the GSM standards so as to minimise the changesrequired by manufactures and operators who wish to support this new technology. Thisincludes maintaining the same frequency plan, meaning that 200kHz will still separatecarriers. In addition, the TDMA structure supported by GSM will remain intact at eighttimeslots per frame. Also, the relationship between logical and physical channels willremain unchanged.

The feasibility study carried out by ETSI on EDGE proposes that it will be able to supportboth circuit switched services: transparent and non–transparent in addition to the packetbased GPRS. These three new services will be called:

ECSD T Enhanced Circuit Switched Data – Transparent.

ECSD NT Enhanced Circuit Switched Data – Non–transparent.

EGPRS Enhanced General Packet Radio Service.

ISSUE 1 REVISION 3 Enhanced Data Rates for GSM Evolution (EDGE)



6–9

EDGE and GSM Comparison

CP07_6_4

UMTS (2Mbps)

EDGE

EGPRS

GPRS

HSCSD

GSM Data 9.6kbps

Packet Data

Circuit Switched Data

GSM Data 14.4kbpsData Rates

ISSUE 1 REVISION 3UMTS



6–10

UMTSUMTS (Universal Mobile Telecommunications System) is the European member of theIMT–2000 family of Third Generation cellular mobile standards.

UMTS will enter the market at a time when fixed–mobile integration is becoming a reality,the telecoms, computer and media industries have converged on Internet Protocol (IP)as a shared standard and data accounts for a significant proportion of the traffic carriedby mobile networks.

UMTS Requirements include:

� Small, low cost pocket terminals

� Worldwide roaming

� A single system for residential, Office, Cellular and Satellite environments

� High Speed Data

Vehicular 144 kb/s

Pedestrian 384 kb/s

Indoor 2Mb/s

UMTS will support data rates of up to 2Mb/s and new multimedia applications over a newwideband air interface based on CDMA techniques. Services will be supported by a widerange of terminals tailored to the requirements of voice, data and multimedia services.

ISSUE 1 REVISION 3 UMTS



6–11

UMTS System Configuration

CP07_6_5

PSTN GMSC

MSC

SGSN

GGSN

Internet

PSDN

BSC

RNC

BTS

Node B

Packet Switched up to 2 Mbit/s

Circuit Switched up to 64kbit/sA

VASServer

HLRAUC

Gb

ISSUE 1 REVISION 3UMTS



6–12

UMTS will encompass more than just cellular systems, evolving from GSM andembracing fixed networks and other wireless and wireline access technologies. Serviceswill be globally available, delivered over the mobile, satellite or fixed networks thatprovides the best accessibility for the consumer’s specific location.

The current vision of most operators is that UMTS will exist as “islands of coverage” withdata services supported by GPRS in areas of lower traffic density. If data demand issufficient it may be economical to upgrade such areas to EDGE, rather than deployW–CDMA. Despite the apparent attractions of deploying EDGE as an incrementalsolution, operators will need to deploy UMTS––as only W–CDMA can support the hightraffic densities encountered in the core of mature networks.

The initial release of the EDGE standard is aimed at increasing the capacity and speedof GPRS data services. The second phase of the EDGE standard will support packetvoice using Voice over IP (VoIP) techniques.

ISSUE 1 REVISION 3 UMTS



6–13

UMTS Islands of Coverage

CPO7_6_6

EDGE

GSM/GPRS

W–CDMAMed QoS

W–CDMAHigh QoS

ISSUE 1 REVISION 3User Benefits of UMTS



6–14

User Benefits of UMTSIn line with subscribers’ increasing expectations of GSM systems, UMTS will of courseprovide a very high quality of service in all environments. This will be further enhanced bythe implementation of the Adaptive Multi–Rate (AMR) codec.

In addition, users will benefit from:

Seamless global roaming

The implementation of the Virtual Home Environment will give users the same seamlessservice regardless of serving network type. This means that users can access theirpersonalised service profile through any network from any terminal, optimise the displayof information and simplify access to the key services that they use most. Thisprogrammable personality will be stored in the SIM card, and this will allow the sameuser interface to be available on any phone anywhere in the world.

High speed data services

The UMTS network will provide cost–effective data transmission with the flexibility toremain on–line at all times, whilst only paying for the amount of data received ortransmitted. Terminals will always be connected to the network, e–mails could bereceived as soon as they are sent and access to the Intranet and Internet will beimmediately available all the time with no set–up delay. All this will be available at evenhigher data rates than those offered by GPRS systems.

Multimedia services

New multimedia services will include video conferencing, interactive entertainment, andvideo transport in the case of an emergency or disaster. Multimedia technology will alsomake it possible to offer electronic magazines or newspapers complete with graphics andvideo clips.

New innovative applications

The involvement of new Value Added Service Providers in the UMTS commercial modelprovides the opportunity for a wide range of new applications to be offered. Examples aresupplementary features for traditional voice callers such as location based services.

Telematics

Building on GPRS services, UMTS will support machine to machine communications inapplications such as vending machine monitoring.

Increased integration between fixed and mobile telephony services

The increased integration of these services offers users both an increase in ease of useand increased affordability.

Increased choice of services

The opening up of the market for service provision and the simplification of servicecreation will provide users with an increased range of services from which to select. Theincrease in competition in the market is also expected to ensure that these services areoffered to the user at an affordable.

ISSUE 1 REVISION 3 User Benefits of UMTS



6–15

UK3G Vision

CPO7_6_7

Home–Cell

In–Building

Urban

Pico–CellMicro–CellMacro–Cell

Suburban

Global

Satellite

Audio/visTerminal

ISSUE 1 REVISION 3UMTS Future Vision



6–16

UMTS Future VisionThe UMTS core network will be based upon a broadband network carrying IP–basedtraffic. An ATM network could provide the quality of service necessary for reliable andefficient transport of multimedia data. Due to the need to support legacy interconnectoptions to the cell site for many years, Frame Relay remains an attractive option tomaximise the efficiency of the BTS backhaul links.

The key changes in the UMTS architecture are that:

� The NSS has moved to an efficient packet–based transport, using low–coststandard packet switches to route the call and signalling traffic. This also requireschanges to the peripherals, such as the voice mail system, which now operates ina packet–based voice–transcoded (and thus higher voice quality) mode.

� The transcoding and data–interworking functions have moved to the periphery ofthe network, where it connects with other networks.

In the future UMTS network, the functions required to control the mobile network areserver based and the underlying broadband network carries out the switching functions.The core platforms are built upon a common hardware and software architecture allowingfunctions to be distributed as required.

ISSUE 1 REVISION 3 UMTS Future Vision



6–17

UMTS Future Vision

CPO7_6_8

ServiceProvider

ServiceMgmt

HLR, SLRGMSC

CAMEL ServerSIM Server

PSTN TIPHONPDN

CircuitGateway

GGSNPacket

Gateway

BSC/RNCServer

UMTSBTS

DualModeBTS

GSMBTS

NMCBroadband

Network

CorporateBTS

In–BuildingSystem

ApplicationServer

UMTSServer

TIPHON = Telephony and Internal ProtocolHarmonization over Networks

ISSUE 1 REVISION 3UMTS Future Vision



6–18



i

Glossary of Terms

ISSUE 1 REVISION 3



ii

ISSUE 1 REVISION 3



iii

Glossary of Terms i. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

A Glos–1. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

B Glos–2. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

C Glos–3. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

D Glos–5. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

E Glos–6. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

F Glos–7. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

G Glos–8. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

I Glos–9. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

L Glos–10. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

M Glos–11. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

N Glos–12. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

P Glos–13. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

Q Glos–15. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

R Glos–16. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

S Glos–17. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

T Glos–19. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

U Glos–20. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

V Glos–21. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .

ISSUE 1 REVISION 3



iv

ISSUE 1 REVISION 3 A



Glos–1

AOn completion of this chapter the student should be able to:

AA Anonymous Access

APN Access Point Name

ATM Asynchronous Transfer Mode

access delay: The value of elapsed time between an access request and a successfulaccess (source: ITU–T X.140).

access protocol: a defined set of procedures that is adopted at an interface at a specifiedreference point between a user and a network to enable the user to employ the servicesand/or facilities of that network (source: ITU–T I.112).

accuracy: A performance criterion that describes the degree of correctness with which afunction is performed. (The function may or may not be performed with the desiredspeed.) (source: ITU–T I.350).

ISSUE 1 REVISION 3B



Glos–2

BBCS Block Check Sequence

BEC Backward Error Correction

BH Block Header

BSSGP Virtual Connection (BVC): An end–to–end virtual communication path betweenremote Network Service user entities.

BSSGP Virtual Connection Identifier (BVCI): The identifier of a BVC, having end–to–endsignificance across the Gb interface.

Block period: A block period is the sequence of four timeslots on a PDCH used to conveyone radio block.

BG Border Gateway

BSSAP+ Base Station System Application Part +

BSSGP Base Station System GPRS Protocol

basic service: The telecommunication services excluding the supplementary services(source: GSM 01.04).

bearer service: A type of telecommunication service that provides the capability for thetransmission of signals between user–network interfaces (source: GSM 01.04, ITU–TI.112).

best effort service: A service model which provides minimal performance guarantees,allowing an unspecified variance in the measured performance criteria.

ISSUE 1 REVISION 3 C



Glos–3

CCS Coding Scheme

CU Cell Update

CCU Channel Codec Unit

CGI Cell Global Identification

CS Circuit Switched

CLNP Connectionless network protocol

CLNS Connectionless network service

CONS Connection–oriented network service

calling user: Entity which originates a call to the General Packet Radio Service (GPRS).

connectionless service: A service which allows the transfer of information among serviceusers without the need for end–to–end call establishment procedures (source: ITU–TI.113).

connectionless–mode transfer:

”The terms ’message’, ’datagram’, ‘transaction mode’ and’connection–free’ have been used in the literature to describe variations on the samebasic theme: the transmission of a unit of data in a single, self–contained operationwithout establishing, maintaining, and releasing a connection.”

”(Connectionless–mode transmission) is the transmission of a single unitof data from a source service–access–point to one or more destinationservice–access–point(s) without establishing a connection. A connectionless–modeservice allows an entity to initiate such a transmission by the performance of a singleservice access.

In contrast to a connection, an instance of the use of aconnectionless–mode service does not have a clearly distinguishable lifetime. In addition,the connectionless–mode service, unless otherwise explicitly determined, has thefollowing fundamental characteristics:

a) no dynamic peer–to–peer agreement is involved in an instance of the service;

b) all of the information required to deliver a unit of data (destination address, quality ofservice selection, options, etc.) is presented to the layer providing theconnectionless–mode service, together with the user data to be transmitted, in a singleservice access. The layer providing the connectionless–mode service is not required torelate this access to any other service access.

As a result of these fundamental characteristics it may also be true that

c) each unit of data transmitted is entirely self–contained and can be routedindependently;

d) copies of a unit of data can be transmitted to a number of destination addresses.”

NOTE: Connectionless–mode transfer normally implies that the service a)does not provide confirmed delivery of SDUs, b) does not guarantee delivery of SDUs, c)does not guarantee maintenance of SDU sequencing and d) does not guaranteeelimination of SDUs.

ISSUE 1 REVISION 3C



Glos–4

connection–mode transfer:

”A connection is an association established for the transfer of databetween two or more peer–entities. This association is established between thepeer–entities themselves and between each entity and the next lower layer. The ability toestablish a connection and to transfer data over it is provided to the entities in a givenlayer by the next lower layer as a connection–mode service. An instance of the use of aconnection–mode service by peer–entities proceeds through three distinct phases ofoperation:

a) connection establishment;

b) data transfer; and

c) connection release.”

NOTE: Connection–mode transfer normally implies that the service a)provides confirmed delivery of SDUs, b) provides ordered, in–sequence delivery of SDUsand c) will not duplicate SDUs.

conversational service: An interactive service which provides for bi–directionalcommunication by means of real–time (no store–and–forward) end–to–end informationtransfer from user to user (source: ITU–T I.113).

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Glos–5

DDNS Domain Name System

demand service: A type of telecommunication service in which the communication path isestablished almost immediately, in response to a user request effected by means ofuser–network signalling (source: GSM 01.04, ITU–T I.112).

dependability: A performance criterion that describes the degree of certainty (or surety)with which a function is performed regardless of speed or accuracy, but within a givenobservational interval (source: ITU–T I.350).

destination user: Entity to which calls to the General Packet Radio Service (GPRS) aredirected.

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Glos–6

Eextra SDU delivery probability: The ratio of total (unrequested) extra service data units(SDUs) to total service data units received by a destination user in a specified sample(source: ITU–T X.140).

NOTE: the term ”user information unit” has been replaced by the term ”servicedata unit”.

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Glos–7

Ffunctional group: A set of functions that may be performed by a single equipment(source: ITU–T I.112).

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Glos–8

GGGSN Gateway GPRS Support Node

GMM/SM GPRS Mobility Management and Session Management

GSN GPRS Support Node

GTP GPRS Tunnelling Protocol

GPRS General packet radio service

GSN GPRS support node

GPRS MS class

The term GPRS MS class refers to the different mobile station implementations and thedifferent modes of operation possible for GPRS, see GSM 02.60. In this ETS, theexpression that a mobile station belongs to a certain GPRS MS class (A, B or C) is usedto denote the case that a mobile station is currently operating according to the RRprocedures specified for the particular GPRS MS class.

The GPRS MS class, to which a mobile station belongs, depends on the GSM servicesto which the mobile station is currently attached, i.e., GSM GPRS services, GSM circuitswitched services including SMS, or both, and to the extent a simultaneous invocation ofthese services is possible. The GPRS MS class a mobile station belongs to may shift intime.

GPRS multislot class

The term GPRS multislot class refers to the different mobile station capabilities totransmit and receive on different combinations of multiple PDCHs. The multislot classesare defined in GSM 05.02. Note that the mobile station may indicate different multislotclasses for circuit mode services and for GPRS (see GSM 04.08). Different multislotclass mobile stations are capable of supporting different medium access modes.

guaranteed service: A service model which provides highly reliable performance, withlittle or no variance in the measured performance criteria.

GTP–Flow: A GTP flow is defined by the unidirectional virtual aggregation ofG–PDUs and/or signalling messages related to one or more GTP tunnels. A GTP flow isidentified by a Flow Label included in the GTP header. The meaning of the Flow Label istransparent for the transmitter side, only the receiver may evaluate the Flow Label.

GTP tunnel: A GTP tunnel is defined by two associated PDP Contexts in differentGSN nodes and is identified with a Tunnel ID. A GTP tunnel is necessary to forwardpackets between an external packet data network and a MS user.

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Glos–9

IIP Internet protocol

IETF Internet Engineering Task Force

IPv4 Internet Protocol version 4

IPv6 Internet Protocol version 6

ISP Internet Service Provider

interactive service: A service which provides the means for bi–directional exchange ofinformation between users. Interactive services are divided into three classes of services:conversational services, messaging services and retrieval services (source: ITU–T I.113).

interface: The common boundary between two associated systems (source: GSM 01.04,ITU–T I.112).

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Glos–10

LLLC Logical Link Control

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Glos–11

MMAC Medium Access Control

MNRF Mobile station Not Reachable Flag

MNRG Mobile station Not Reachable for GPRS flag

MNRR Mobile station Not Reachable Reason

mean bit rate: A measure of throughput. The average (mean) bit rate available to theuser for the given period of time (source: ITU–T I.210).

mean transit delay: The average transit delay experienced by a (typically) large sample ofPDUs within the same service category.

messaging service: An interactive service which offers user–to–user communicationbetween individual users via storage units with store–and–forward, mailbox and/ormessage handling, (e.g., information editing, processing and conversion) functions(source: ITU–T I.113).

mobile station: Equipment intended to access a set of GSM PLMN telecommunicationservices. Services may be accessed while the equipment capable of surface movementwithin the GSM system area is in motion or during halts at unspecified points (source:GSM 01.04).

mobile termination: The part of the mobile station which terminates the radiotransmission to and from the network and adapts terminal equipment capabilities to thoseof the radio transmission (source GSM 01.04).

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Glos–12

NNSDU Network service data unit

NGAF Non–GPRS Alert Flag

NS Network Service

Network Service Virtual Connection (NS–VC): An end–to–end virtual communication pathbetween Network Service peer entities.

Network Service Virtual Connection (NS–VCI) Identifier: The identifier of an NS–VChaving end–to–end significance across the Gb interface.

Network Service Virtual Link (NS–VL): A virtual communication path between the BSS orthe SGSN and the intermediate network, or between the BSS and the SGSN in case ofdirect point–to–point configuration.

Network Service Virtual Link Identifier (NS–VLI): The identifier of an NS–VL, having localsignificance at the BSS or SGSN.

Network Service Virtual Connection Group: Groups NS–VCs together which providecommunication between the same peer NS entities. This grouping has local significanceat the BSS or SGSN.

NSAPI Network layer Service Access Point Identifier. For each SN–PDU theNSAPI is an index to the PDP context of the PDP that is using the services provided bythe SNDCP layer.

NSS Network SubSystem

network connection: An association established by a network layer between two users forthe transfer of data, which provides explicit identification of a set of network datatransmissions and agreement concerning the services to be provided by the set (source:ITU–T X.213 / ISO–IEC 8348).

network operator: Entity which provides the network operating elements and resourcesfor the execution of the General Packet Radio Service (GPRS).

network service data unit (NSDU): A unit of data passed between the user and theGPRS network across a Network Service Access Point (NSAP).

network termination: A functional group on the network side of a user–network interface(source: ITU–T I.112).

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Glos–13

PPACCH Packet Associate Control Channel

PAGCH Packet Access Grant Channel

PBCCH Packet Broadcast Control Channel

PC Power Control

PCCCH Packet Common Control Channel

PDCH Packet Data Channel

PDTCH Packet Data Traffic Channel

PDU Protocol Data Unit

PL Physical Link

PNCH Packet Notification Channel (for PTM–M on PCCCH)

PPCH Packet Paging Channel

PRACH Packet Random Access Channel

P–TMSI Packet TMSI

PCU Packet Control Unit

PDCH Packet Data CHannel

PDN Packet Data Network

PDP Packet Data Protocol, e.g., IP or X.25 [33]

PDU Protocol Data Unit

PPF Paging Proceed Flag

PTM Point To Multipoint

PTP Point To Point

PVC Permanent Virtual Circuit

PLMN Public land mobile network

Packet idle mode: (only applicable for mobile stations GPRS of class A, B or C): In thismode, the mobile station is prepared to transfer LLC PDUs on packet data physicalchannels. The mobile station is not allocated any radio resource on a packet dataphysical supporting channel; it listens to the PBCCH and PCCCH or, if those are notprovided by the network, to the BCCH and the CCCH.

Packet transfer mode: (only applicable for mobile stations supporting GPRS of class A, Bor C): In this mode, the mobile station is prepared to transfer LLC PDUs on packet dataphysical channels, see clause 5. The mobile station is allocated radio resource on one ormore packet data physical channels for the transfer of LLC PDUs.

packet: An information unit identified by a label at layer 3 of the OSI reference model(source: ITU–T I.113). A network protocol data unit (NPDU).

packet data protocol (PDP): Any protocol which transmits data as discrete units knownas packets, e.g., IP, or X.25.

packet transfer mode: Also known as packet mode. A transfer mode in which thetransmission and switching functions are achieved by packet oriented techniques, so as

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Glos–14

to dynamically share network transmission and switching resources between amultiplicity of connections (source: ITU–T I.113).

peak bit rate: A measure of throughput. The maximum bit rate offered to the user for agiven time period (to be defined) for the transfer of a bursty signal (source: ITU–T I.210).(The maximum user information transfer rate achievable by a user for a single servicedata unit transfer.)

PLMN Operator: Public Land Mobile Network operator. The entity which offers a GPRS.

point–to–point (PTP): A value of the service attribute ”communication configuration”,which denotes that the communication involves only two network terminations.

point–to–point (PTP) service: A service type in which data is sent from a single networktermination to another network termination.

predictive service: A service model which provides reliable performance, but allowing aspecified variance in the measured performance criteria.

protocol: A formal set of procedures that are adopted to ensure communication betweentwo or more functions within the within the same layer of a hierarchy of functions (source:ITU–T I.112).

protocol data unit (PDU): In the reference model for OSI, a unit of data specified in an(N)–protocol layer and consisting of (N)–protocol control information and possibly(N)–user data (source: ITU–T X.200 / ISO–IEC 7498–1).

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Glos–15

QQoS Quality of service

quality of service: The collective effect of service performances which determine thedegree of satisfaction of a user of the service (ITU–T E.800). The set of performanceparameters that can be directly observed and measured at the point at which the serviceis accessed by the user. There are three criteria by which performance is measured:speed, accuracy and dependability (source: ITU–T I.350).

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Glos–16

RRA Routeing Area

RAC Routeing Area Code

RAI Routeing Area Identity

RLC Radio Link Control

Radio block: A radio block is the sequence of four normal bursts carrying one RLC/MACprotocol data unit. (The one exception is a radio block occasionally used on PACCHconsisting of a sequence of four access bursts, each carrying a repetition of one shortRLC/MAC block.)

RLC/MAC block: A RLC/MAC block is the protocol data unit exchanged betweenRLC/MAC entities, see clause 10.

RLC/MAC control block: A RLC/MAC control block is the part of a RLC/MAC blockcarrying a control message between RLC/MAC entities.

RLC data block: A RLC data block is the part of a RLC/MAC block carrying user data orupper layers’ signalling data.

reference configuration: A combination of functional groups and reference points thatshows possible network arrangements (source: GSM 01.04, ITU–T I.112).

reference point: A conceptual point at the conjunction of two non–overlapping functionalgroups (source: GSM 01.04, ITU–T I.112).

residual error rate: A parameter describing service accuracy. The frequency of lostSDUs, and of corrupted or duplicated network SDUs delivered at the user–networkinterface.

retrieval service: An interactive service which provides the capability of accessinginformation stored in data base centres. The information will be sent to the user ondemand only. The information is retrieved on an individual basis, i.e., the time at which aninformation sequence is to start is under the control of the user (source ITU–T I.113).

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Glos–17

SSAP Service access point

SVC Switched virtual circuit

SDU Service data unit

SGSN Serving GPRS Support Node

SM Short Message

SM–SC Short Message service Service Centre

SMS–GMSC Short Message Service Gateway MSC

SMS–IWMSC Short Message Service Interworking MSC

SN–PDU SNDCP PDU

SNDC SubNetwork Dependent Convergence

SNDCP SubNetwork Dependent Convergence Protocol

SDU error probability: The ratio of total incorrect service data units (SDUs) to totalsuccessfully transferred service data units plus incorrect service data units in a specifiedsample (source: ITU–T X.140).

NOTE: the source document term ”user information unit” has been replaced bythe term ”service data unit”.

SDU loss probability: The ratio of total lost service data units (SDUs) to total transmittedservice data units in a specified sample (source: ITU–T X.140).


SDU misdelivery probability: The ratio of total misdelivered service data units (SDUs) tototal service data units transferred between a specified source and destination user in aspecified sample (source: ITU–T X.140).


SDU transfer delay: The value of elapsed time between the start of transfer andsuccessful transfer of a specified service data unit (SDU) (source: ITU–T X.140).


SDU transfer rate: The total number of successfully transferred service data units (SDUs)in a transfer sample divided by the input/output time for that sample. The input/outputtime is the larger of the input time or the output time for the sample (source: ITU–TX.140).


service access point (SAP): In the reference model for OSI, the points through whichservices are offered to an adjacent higher layer (source: GSM 01.04, ITU–T X.200 /ISO–IEC 7498–1).

service attribute: A specified characteristic of a telecommunication service (source:ITU–T I.112). NOTE: the value(s) assigned to one or more service attributesmay be used to distinguish that telecommunications service from others.

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Glos–18

service bit rate: The bit rate that is available to a user for the transfer of user information(source: ITU–T I.113).

service category or service class: A service offered to the users described by a set ofperformance parameters and their specified values, limits or ranges. The set ofparameters provides a comprehensive description of the service capability.

service data unit (SDU): In the reference model for OSI, an amount of information whoseidentity is preserved when transferred between peer (N+1)–layer entities and which is notinterpreted by the supporting (N)–layer entities (source: ITU–T X.200 / ISO–IEC 7498–1).

service delay: The time elapsed from the invocation of the service request, to thecorresponding service request indication at the Service Receiver, indicating the arrival ofapplication data.

service model: A general characterisation of services based upon a QoS paradigm,without specifying the actual performance targets.

service provider: Entity which offers the General Packet Radio Service (GPRS) forsubscription. The network operator may be the service provider.

service receiver: The entity which receives the service request indication primitive,containing the SDU.

service request: This is defined as being one invocation of the service through a servicerequest primitive.

service requester: The entity which requests the initiation of a GPRS operation, through aservice request.

service subscriber: Entity which subscribes to the General Packet Radio Service (GPRS)service.

signalling: The exchange of information specifically concerned with the establishment andcontrol of connections, and with management, in a telecommunications network (source:ITU–T I.112).

simultaneous use of services: The concurrent use of a GSM circuit–mode service (voiceor data) and GSM packet–mode services (GPRS) by a single mobile station.

speed: A performance criterion that describes the time interval required to perform afunction or the rate at which the function is performed. (The function may or may not beperformed with the desired accuracy.) (source: ITU–T I.350).

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Glos–19

TTA Timing Advance

TBF Temporary Block Flow

TFI Temporary Frame Identity

Temporary Block Flow (TBF): A Temporary Block Flow (TBF) is a physical connectionused by the two RR peer entities to support the unidirectional transfer of LLC PDUs onpacket data physical channels.

TCAP Transaction Capabilities Application Part

TCP Transmission Control Protocol

TID Tunnel Identifier

TRAU Transcoder and Rate Adaptor Unit

TLLI Temporary link level identity

teleaction service: A type of telecommunication service that uses short messages,requiring a low transmission rate, between the user and the network (source: ITU–TI.112).

telecommunication service: That which is offered by a PLMN operator or service providerto its customers in order to satisfy a specific telecommunication requirement. (source:GSM 01.04, ITU–T I.112). Telecommunication services are divided into two broadfamilies: bearer services and teleservices (source: ITU–T I.210).

teleservice: A type of telecommunication service that provides the complete capability,including terminal equipment functions, for communication between users according toprotocols established by agreement between Administrations (source: GSM 01.04,ITU–T I.112).

terminal equipment: Equipment that provides the functions necessary for the operation ofthe access protocols by the user (source: GSM 01.04). A functional group on the userside of a user–network interface (source: ITU–T I.112).

throughput: A parameter describing service speed. The number of data bits successfullytransferred in one direction between specified reference points per unit time (source:ITU–T I.113).

transit delay: A parameter describing service speed. The time difference between theinstant at which the first bit of a protocol data unit (PDU) crosses one designatedboundary (reference point), and the instant at which the last bit of the PDU crosses asecond designated boundary (source: ITU–T I.113).

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Glos–20

UUDP User Datagram Protocol

Uplink State Flag (USF): The Uplink State Flag (USF) is used on PDCH channel(s) toallow multiplexing of uplink Radio blocks from different mobile stations.

user access or user network access: The means by which a user is connected to atelecommunication network in order to use the services and/or facilities of that network(source: GSM 01.04, ITU–T I.112).

user–network interface: The interface between the terminal equipment and a networktermination at which interface the access protocols apply (source: ITU–T I.112).

user–user protocol: A protocol that is adopted between two or more users in order toensure communication between them (source: ITU–T I.112).

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Glos–21

Vvariable bit rate service: A type of telecommunication service characterised by a servicebit rate specified by statistically expressed parameters which allow the bit rate to varywithin defined limits (source: ITU–T I.113).

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Glos–22

Documents

Introduction to GPRS - Motorola Training