Handover control system, user terminal, signaling relay apparatus, and session control apparatus
The invention discloses a technique to adequately control a handover of a user terminal in a data communication network and to decrease the number of signalings. According to this technique, when address of a user terminal (UE ( 101 )) is not changed after a handover, UE ( 101 ) transmits a session update signaling message to carry out update processing of application session to P-CSCF 1 ( 121 ) corresponding to a location before the handover via P-CSCF 2 ( 123 ) corresponding to a location after the handover. P-CSCF 1 ( 121 ) transfers a session update signaling message to S-CSCF/AS ( 125 ) by using setup of signaling relating to UE ( 100 ) before the handover. At S-CSCF/AS ( 125 ), the application session is updated by using registration information of UE ( 100 ) before the handover.
1. A method of updating an IP multimedia subsystem (IMS) session comprising:
when a user terminal performs a handover from a first access network to a second access network, wherein an address of the user terminal is not changed, and an entity supporting signaling of the IMS session is changed from a first Proxy Call Session Control Function (P-CSCF) to a second P-CSCF:
the second P-CSCF receives an IMS session update message including a flag indicating that registration of a new IMS session is not made and an information element relating to the first P-CSCF from the user terminal, updates the IMS session update message, and transmits the IMS session update message to the first P-CSCF, the first P-CSCF and the second P-CSCF being entities supporting signaling of the IMS session;
the first P-CSCF receives the IMS session update message from the second P-CSCF, and transmits the IMS session update message to a Serving Call Session Control Function (S-CSCF); and
the S-CSCF receives the IMS session update message from the first P-CSCF, and updates the IMS session based on the IMS session update message using signaling of a setup of said user terminal, wherein the setup is performed before said handover.
2. The method according to claim 1 , wherein the updating the IMS session update message by the second P-CSCF includes adding address information of the second P-CSCF.
3. The method according to claim 1 , wherein the updating the IMS session by the S-CSCF includes updating address information of the second P-CSCF.
4. A system of updating an IP multimedia subsystem (IMS) session comprising:
a user terminal;
a first Proxy Call Session Control Function (P-CSCF) and a second P-CSCF, the first and second P-CSCFs being entities supporting signaling of the IMS session; and
a Serving Call Session Control Function (S-CSCF),
wherein, when a user terminal performs a handover from a first access network to a second access network, wherein an address of the user terminal is not changed, and an entity supporting signaling of the IMS session is changed from a first Proxy Call Session Control Function (P-CSCF) to a second P-CSCF:
the second P-CSCF is configured to receive an IMS session update message including a flag indicating that registration of a new IMS session is not made and an information element relating to the first P-CSCF form the user terminal, to update the IMS session update message, and to transmit the IMS session update message to the first P-CSCF, the second P-CSCF being an entity supporting signaling of the IMS session;
the first P-CSCF is configured to receive the IMS session update message from the second P-CSCF, and to transmit the IMS session update message to the S-CSCF; and
the S-CSCF configured to receive the IMS session update message from the first P-CSCF, and to update the IMS session based on the IMS session update message using signaling of a setup of said user terminal, wherein the setup is performed before said handover.
5. The system according to claim 4 , wherein the updating the IMS session update message by the second P-CSCF includes adding address information of the second P-CSCF.
6. The system according to claim 4 , wherein the updating the IMS session by the S-CSCF includes updating address information of the second P-CSCF.