A study on switching voice traffic seamlessly between GSM and GPRS cellular networks

As cellular carriers start deploying packet data services such as General Packet Radio Service (GPRS) and 3G cellular networks, packet-switched voice services such as VoIP will be available over the cellular network in the near future. When the existing circuit-switched radio interface and the newly deployed packet-switched radio interface coexist in a cell, the mobile station user may have an option between the circuit-switched call and the VoIP call. While the circuit-switched voice offers a better call quality, the VoIP connection offers a better radio resource utilization. In this paper, we introduce dynamic QoS control schemes for voice traffic, where Class-A GPRS mobile station users can switch their ongoing GSM calls to VoIP calls and vice versa seamlessly in the SIP-enabled GSM/GPRS cellular network based on their desired quality of service. Due to the VoIP's less radio resource demand, these schemes can also be used by the base station controller to handle the dynamically changing load in a cell.