Inter-system handover using legacy interface

摘要

Techniques for performing inter-system handover are described. An Access Gateway (AGW) sends a message requesting handover of a user equipment (UE) from a first radio access network (RAN) to a second RAN. The message is sent to an Inter Access System (inter-AS) Anchor for the first RAN communicating with an SGSN for the second RAN via a Gn interface. The Inter-AS Anchor and SGSN exchange messages via the Gn interface, and the Inter-AS Anchor forwards the messages to the AGW to handover the UE from the first RAN to the second RAN. The SGSN sees the Inter-AS Anchor as another SGSN for the handover and as a GGSN after the handover. This allows the inter-system handover to be achieved with an inter-SGSN SRNS relocation procedure used for handover between two SGSNs, which reduces impact on the SGSN to support the inter-system handover.