HAND-OVER METHOD AND APPARATUS BETWEEN DIFFERENTIAL SYSTEMS

摘要

A handover method and device between different systems are provided to allow a UE(User Equipment) to use an IP(Internet Protocol) address, which the UE has received in an UMTS(Universal Mobile Telecommunication Service) existing system, as it is when performing handover between an E-UMTS(Enhanced-UMTS) system and the existing UMTS system without changing an existing SGSN(Serving GPRS Support Node), an RNC(Radio Network Controller), or a node B. A UE, which performs communication through an E-UMTS, measures signal strength from a UMTS system, and transmits a measurement report message including the measured signal strength to the E-UMTS system. When the measured signal strength included in the measurement report message is greater than a particular threshold value, it is determined to perform handover from the E-UMTS system to the UMTS system. As the handover is determined, an E-CN(Core Network) of the E-UMTS system establishes a tunnel for user data with a CN node of the UMTS system. After the tunnel is established, the E-UMTS system transmits a handover command message to the UE. The UE is connected with the UMTS system in response to the handover command message. User data related to the UE is transferred through the tunnel between the E-CN of the E-UMTS system and the CN node of the UMTS system.