Enhanced circuit switched data for real time services over GSM

The deployment of the HSCSD (high speed circuit switched data) is starting in GSM networks. This brings multislot capability to GSM and significantly enhances the available data rates together with the introduction of the 14.4 kbps per time slot data rate. The next step in the evolution of the real-time GSM services is the enhanced circuit switched data (ECSD) which is being developed in ETSI as GSM Phase 2+ work item (EDGE Phase I) parallel to enhanced general packet radio service (EGPRS). The ECSD radio interface deploys 8-PSK modulation in addition to GMSK and thus enables higher data throughput per time slot. The ECSD type radio interface can also be seen as a candidate in the development of real-time services for the evolving mobile networks. This paper focuses on the ECSD concept and presents its essential features as they are defined at the moment, before finalisation of the standard.