Nowadays, when we speak of GSM, we usually mean ªoriginalº GSM ± also known as GSM900 since 900 MHz was the original frequency band. To provide additional capacity and enable higher subscriber densities, two other systems were added later: GSM1800 (also DCS1800) and GSM1900 (also PCS 900). | sfâLùJ VOL 2 Pocket Guide Wandel Goltermann Communications Test Solutions g Pocket Guide for Fundamentals and GSM Testing Publisher Wandel Goltermann GmbH Co Elektronische Meßtechnik RO. Box 1262 D-72795 Eningen . Germany e-mail solutions@ http Author Marc Kahabka CONTENTS 1 Mobility - The magic word . 3 2 GSM overview . 5 3 GSM system architecture. 7 4 Interfaces and protocols .11 5 The air interface Logical channels on the air Traffic channels on the air Signaling channels on the air interface .18 Burst Protocols on the air 6 The Abis interface .24 The TRAU Protocols on the Abis 7 The A interface . 30 Protocols on the A 8 MSC-based MSC protocols .33 9 Call 10 Test and measurement problems in GSM . 37 11 Outlook .46 12 GSM 13 Bibliography . 51
