Enhanced voice over IP support in GPRS and EGPRS

In this paper we discuss the applicability of GPRS and EGPRS for the transmission of voice packets in an end-toend packet switched scenario. We assume typical Voice over IP (VoIP) applications spanning between a fixed and a mobile terminal. As the transmission delay of the voice packets has most impact on the perceived Quality of Service (QoS), it has been put into focus of our investigations. The studies have been aided by an end-to-end simulation environment modeling the protocol stack applied in (E)GPRS. The first assessments performed were dedicated to obtain performance figures of standard (E)GPRS systems carrying VoIP data. In a second step, the mechanisms and procedures having most relevance to the transmission delay in (E)GPRS are identified and improvements are proposed. These improvements start from smaller modifications of the standard system and end at modifications of the multiplexing schemes applied on the radio interface. As we will see, the typical transmission delay of (E)GPRS is thus stepwise improved at the expense of increased modifications of the system.