Réseaux cellulaires

Modern telecommunications networks generally use packet data transmission, while voice is transmitted in circuit mode. GSM (Global System for Mobile Communications) cellular networks, initially designed to carry mobile telephony and, secondarily, data in circuit mode, have been offering packet mode transmission since 2002, thanks to a major development: GPRS (General Packet Radio Services). Without having to change all the equipment on the existing GSM infrastructure network, by adding two new pieces of equipment, the GGSN and the SGSN, transmission speeds of up to 171 kbits/s can be achieved instead of 14.4 kbits/s in circuit mode, with controlled quality of service and the new possibility of simultaneous voice and data usage. A change of modulation (8PSK instead of GSMK) makes it possible to go even further, leading to the EDGE/GPRS network concept, a declared alternative, at least for a few years, to third-generation networks such as UMTS.

A table giving the meaning of the acronyms and abbreviations used can be consulted at the end.