On Handover Procedure with Data Forwarding for Reducing Buffered User Data in Base Stations

Network-based localized mobility management is a promising approach for seamless migration of mobile network operators to service provisioning with multiple access network technologies. The tunnel-based data-forwarding approach, which is friendly to network-based localized mobility management, realizes seamless mobility, that is, no user-data loss and short disruption of mobile node (MN) communications. This approach buffers user data (packets) when an MN makes a handover. The required amount of the buffer substantially increases when a large number of MNs make handovers simultaneously. We analyze the relationship between the amount of the buffered user data, and the propagation delays of signaling messages and user data for two types of handover procedures which have been standardized in 3GPP. And then, modifications to the handover procedures are proposed in terms of reducing buffered user data. A packet-based simulation shows that the modifications can reduce the buffered user data to one-tenth at maximum. The proposal also includes a realistic architectural indication on the link delay alignment.