On reducing packet buffering for network-based fast handover cooperating with IMS

For seamless mobility in networks that use Proxy Mobile IPv6, Proxy Fast Mobile IPv6 (PFMIPv6) is being standardized. The predictive handover mode of PFMIPv6 can minimize packet loss by forwarding user data from the old mobile access gateway (MAG) to the new MAG to which the mobile terminal (MT) makes a handover and by buffering the forwarded data at the new MAG until the MT is attached to the new MAG. In the case where handover is prolonged, the user data delivered after the MT attachment results in a large delay and jitter, and could be treated as actual packet loss. We propose a novel data buffering scheme to reduce the amount of buffered user data along with the application requirements which IP Multimedia Subsystem (IMS) provides. Our scheme discards the forwarded user data in the case where the user data has large jitter, and where discarding has no substantial impact on the quality of the application. A packet-based simulation to evaluate the proposal shows that the buffered user data are reduced by up to 50% compared with unlimited buffering. The proposed scheme does not require any change to the PFMIPv6 procedure, which is an advantage in terms of implementation.