MINIMISATION OF HANDOVER GAP TIME IN THE CONTEXT OF S2A IP SESSION MOBILITY

摘要

The application relates to session mobility between 3GPP, such as UMTS and LTE, networks and non-3GPP, such as WLAN, access networks and in particular network-based mobility where the PDN gateway PDN GW acts as the user-plane anchor between the two. This topic is discussed in 3GPP, ongoing work item Study on S2a Mobility based On GTP & WLAN access to EPC, SaMOG, TR 23.852; and TS 23.402. Within the SaMOG Rel-12 study, a number of solutions for handover with IP address preservation have been proposed, see 3GPP TR 23.852 section 8.2. However, the current standards do not prevent that that in case of handover, the UE interface for the source path might be released before the configuration for the target path interface has been configured and the UE might not have any interface at all. Hence, the application proposes that release of the source path resources is delayed until the relevant network node has received an indication that the UE has configured its communication interface for the target path. This indication might be in the form of a timer expiry (S606; S616) or in the form of an explicit notification message (S715).