Predictive Discarding of Registration for Fast Recovery of IMS-based Services

摘要

This paper proposes a method for fast reovery of IP Multimedia Subsystem (IMS) -based services, when the network connectivity after the network faults and disaster is recovered. IMS has been standardized for service stratum of fixed and mobile network. Because a large amount of user terminals (UTs) are assumed to use the IMS-based services, the scalability of the IMS nodes which treat signaling messages becomes an important issue. To use the IMS-based services, UTs need to send Register messages defined in Session Initiation Protocol to the IMS nodes. The network recovery scenario leads the IMS nodes heavily-loaded, because a large amount of Register messages arrive at the IMS nodes. They cannot quickly return the response, and UTs retransmits the Register messages. These messages encourage the load in the IMS nodes and delay the registration process of more UTs, because the IMS nodes redundantly process them. This paper proposes a predictive discarding for the fast recovery of IMS-based service. The proposed method discards the Register messages which the response will not arrive within the retransmission timer. The proposed method measures the round-trip time of Register messages, predict the round-trip time of the arrival Register messages, and decides whether the Register messages are discarded or not from that round-trip time. This paper shows the validness of the predictive discarding, compared to the existing works tackling the scalability issues of the IMS nodes.