Mobile technologies GSM

Overview

The technology behind the Global System for Mobile communication (GSMTM) uses Gaussian Minimum Shift Keying (GMSK) modulation a variant of Phase Shift Keying (PSK) with Time Division Multiple Access (TDMA) signalling over Frequency Division Duplex (FDD) carriers. The physical layer is specified in 3GPPTM TS 45.001 and the logical channels in 3GPPTM TS 45.002. The modulation is specified in 3GPPTM TS 45.004.

Although originally designed for operation in the 900 MHz band, it was soon adapted for 1800 MHz. The introduction of GSM into North America meant further adaptation to the 800 and 1900 MHz bands. Over the years, the versatility of GSM has resulted in the specifications being adapted to many more frequency bands to meet niche markets. A full list can be found in 3GPPTM TS 45.005.

GSM was designed principally for voice telephony, but a range of bearer services was defined (a subset of those available for fixed line Integrated Services Digital Networks, ISDN), allowing circuit-switched data connections at up to 9600 bits/s. At the time of the original system design, this rate compared favourably to those available over fixed connections. However, with the passage of time, fixed connection data rates increased dramatically. The GSM channel structure and modulation technique did not permit faster rates, and thus the High Speed Circuit-Switched Data (HSCSD) service was introduced in the GSM Phase 2+.

In the course of the next few years, the General Packet Radio Service (GPRS) was developed to allow aggregation of several carriers for higher speed, packet-switched applications such as always-on internet access. The first commercial GPRS offerings were introduced in the early 2000s.

Meanwhile, investigations had been continuing with a view to increasing the intrinsic bit rate of the GSM technology via novel modulation techniques. This resulted in Enhanced Data-rates for Global Evolution (EDGE), which offers an almost three-fold data rate increase in the same bandwidth.

The combination of GPRS and EDGE brings system capabilities into the range covered by the International Telecommunication Unions IMT-2000 (third generation) concept, and some manufacturers and network operators consider the EDGE networks to offer third generation services.

GSM radio technology is specified in the 3GPPTM TS 45.-series specifications. The overall GSM network architecture is described in 3GPPTM TS 23.002 and a complete list of Technical Specifications for GSM systems is given in 3GPPTM TS 41.101.



Standards

The following is a list of recently published and frequently downloaded standards. Please use the ETSI Work Programme to find further related standards.

Standard No.Standard Title
3GPPTM TS 45.001 Physical layer on the radio path; General description
3GPPTM TS 45.002 Multiplexing and multiple access on the radio path
3GPPTM TS 45.005 Radio transmission and reception
3GPPTM TS 23.002 Network architecture
3GPPTM TS 41.101 Technical Specifications and Technical Reports for a GERAN-based 3GPPTM system