Further evolution of the GSM/EDGE radio access network

The standardization of the first releases of third-generation cellular systems was finalized in ETSI/3GPP Release 99. Two major systems in this standard are the universal mobile telecommunications system (UMTS) and the global system for mobile communication/enhanced data rates for global evolution (GSM/EDGE). UMTS has been tailored to offer thirdgeneration services—that is, high user data rates for real-time as well as traditional nonreal-time applications. The tailoring comprises both the UMTS core network and the WCDMA-based UMTS terrestrial radio access network. UMTS is currently intended for use in the designated UMTS/IMT-2000 spectrum (and possibly 1,900 MHz), whereas the aim of GSM/EDGE is to evolve GSM and TDMA to provide coverage for third-generation services in existing spectrum bands (700, 850, 900, 1,800 and 1,900 MHz), and to complement UTRAN as a fully capable radio access network that can be connected to the UMTS core network. By introducing high-level modulation in the GSM radio interface, it is expected that EDGE will successfully manage to provide support for high data rates. The next step in the GSM/EDGE evolution is to provide support for conversational and streaming service classes (real-time services). A driver of this evolution is the shift within the telecommunications world from circuit switching to packet switching. This shift is valid for traditional non-real-time data services, such as e-mail and Web browsing, as well as for real-time services, such as video conferencing and voice over IP (VoIP). The second-generation packet-switched core network (which was defined for general packet radio service, GPRS) and the current GSM/EDGE radio access network must each be modified to support real-time services. This includes adopting the Iu interface to the third-generation UMTS core network. Doing so simplifies the alignment of services that will be provided in UMTS,