DS-41 and UMTS intersystem roaming

Currently, two 3rd-generation CDMA (code division multi access) systems have been standardized. The UMTS (Universal Mobile Telecommunication System) adopts W-CDMA (wideband CDMA) direct spread (DS) air interface and the cdma2000 system adopts the cdma2000 multicarrier (MC) air interface. Currently the UMTS system is connected to a GSM-MAP based network protocol and the cdma2000 system is connected to an ANSI-41 based network protocol. There are ongoing harmonization efforts to cross-connect the W-CDMA DS to the ANSI-41 based network (the "DS-41" air interface) and the cdma2000 MC to the GSM-MAP based network (the "MC-MAP" air interface). The DS-41 air interface uses the physical layer, link layer and the radio resource control of W-CDMA DS but uses the mobility management and call control of the cdma2000 system. On the other hand, the MC-MAP uses the physical layer, link layer and the radio resource control of cdma2000 MC but uses the mobility management and the call control of the W-CDMA DS. This paper discusses the necessary DS-41 modifications, particularly with respect to the authentication procedure. This paper also considers the authentication procedures during roaming between the DS-41 and the UMTS systems. Call flows are presented to support the studies.