Method for reselecting bearer binding and event report function

A method for a Bearer Binding and Event Report Function (BBERF) relocation in a local breakout roaming scenario, which is used in a process of the BBERF relocation after establishing a first Internet Protocol (IP) Connectivity Access Network (IP-CAN) session for a User Equipment (UE) and establishing a first gateway control session, a first Gx session, an S9 session and a first subsession of the S9 session which are used to perform policy control to said first IP-CAN session in an Evolved Packet System (EPS), said method comprising:

• establishing a second gateway control session between a destination BBERF and a visited Policy and Charging Rules Function (PCRF);
• and
• if an IP-CAN session modification indication message sent by a Policy and Charging Enforcement Function (PCEF) is received, said visited PCRF linking said first Gx session that said IP-CAN session modification indication message requests to modify to said second gateway control session and said first subsession according to session identity information;
• or
• if an IP-CAN session establishment indication message sent by said PCEF is received, said visited PCRF linking a second Gx session that said IP-CAN session establishment indication message requests to establish to said second gateway control session and said first subsession according to session identity information.

A system for a Bearer Binding and Event Report Function (BBERF) relocation comprising:

• a first processor and a first storage device in a network element that a visited Policy and Charging Rule Function (PCRF) is located, a second processor and a second storage device in a network element that a home PCRF is located, and a third processor and a third storage device in a network element that a Policy and Charging Execution Function (PCEF) is located, a forth processor and a forth storage device in a network element that a BBERF is located, each storage device for storing processor executable instructions that when executed by the corresponding processor cause the corresponding processor to perform the steps in the following function entities:
• after establishing a first IP Connectivity Access Network (IP-CAN) session for a User Equipment (UE) in an Evolved Packet System (EPS) and establishing a first gateway control session, a first Gx session, an S9 session and a first subsession of the S9 session that are used to perform policy control to the first IP-CAN session, and in a process of the BBERF relocation in a local breakout roaming scenario:
• the PCEF is configured to:
• send an IP-CAN session modification indication message or an IP-CAN session establishment indication message to the visited PCRF;
• the BBERF is configured to:
• establish a second gateway control session between the BBERF and the visited PCRF when the BBERF is a destination BBERF;
• the visited PCRF is configured to:
• link said first Gx session that said IP-CAN session modification indication message requests to modify to said second gateway control session and said first subsession according to session identity information;
• or link a second Gx session that said IP-CAN session establishment indication message requests to establish to said second gateway control session and said first subsession according to session identity information;
• the home PCRF is configured to:
• newly make a policy for a user or modify a policy for a user, and provide the policy to said visited PCRF through said first subsession.

A policy and charging rule function (PCRF), comprising a processor and a storage in a network element that a visited PCRF is located, the storage device for storing processor executable instructions that when executed by the processor cause the processor to perform the steps in the visited PCRF in a breakout roaming scenario, wherein in a process of a Bearer Binding and Event Report Function (BBERF) relocation after establishing a first Internet Protocol (IP) Connectivity Access Network (IP-CAN) session for a User Equipment (UE) and establishing a first gateway control session, a first Gx session, an S9 session and a first subsession of the S9 session which are used to perform policy control to said first IP-CAN session in an Evolved Packet System (EPS),

• the visited PCRF is configured to:
• establish a second gateway control session with a destination BBERF;
• and
• receive an IP-CAN session modification indication message sent by a Policy and Charging Enforcement Function (PCEF), and link said first Gx session that said IP-CAN session modification indication message requests to modify to said second gateway control session and said first subsession according to session identity information;
• or
• receive an IP-CAN session establishment indication message sent by said PCEF, and link a second Gx session that said IP-CAN session establishment indication message requests to establish to said second gateway control session and said first subsession according to session identity information.