Base station device, terminal device, and communication control method

A terminal device having a first packet data network (PDN) connection established with a core network, an isolated E-UTRAN function being a function of a base station device or a gateway transferring user data when the base station device is in a first state where connectivity to the core network is lost and/or a second state where a restriction on connectivity to the core network is imposed,

• the terminal device being configured to:
• receive, from the base station device, a notification message indicating that the base station device is in the first state and/or the second state;
• detach the first PDN connection on the basis of the notification message;
• when permission information indicating that communication based on the isolated E-UTRAN function is permitted is stored,
• initiate an attach procedure by transmitting, to the base station device, an attach request message including at least the permission information;
• and
• when permission information indicating that communication based on the isolated E-UTRAN function is permitted is not stored,
• not initiate the attach procedure.

A communication control method for a base station device, comprising the steps of:

• transmitting, to a terminal device, a notification message indicating that the base station device is in a first state where connectivity to a core network is lost and/or a second state where a restriction on connectivity to the core network is imposed;
• receiving an attach request message from the terminal device;
• when the attach request message includes permission information,
• transmitting an attach permission message to the terminal device as a response to the attach request message, the permission information being permission information indicating that communication based on an isolated E-UTRAN function is permitted,
• the isolated E-UTRAN function being a function of the base station device or a gateway transferring user data when the base station device is in the first state where connectivity to the core network is lost and/or the second state where a restriction on connectivity to the core network is imposed;
• and
• when the attach request message does not include the permission information,
• transmitting an attach reject message to the terminal device as a response to the attach request message.

A communication control method for a terminal device, comprising the steps of:

• transmitting an attach request message to a base station device;
• and
• receiving an attach reject message that is a response to the attach request message and includes at least cause information indicating that establishing a connection to an isolated E-UTRAN is not permitted,
• the isolated E-UTRAN being an access network having the base station device in a first state where connectivity to a core network is lost and/or a second state where a restriction on connectivity to the core network is imposed.

A communication control method for a terminal device, comprising the steps of:

• establishing a first packet data network (PDN) connection with a core network to allow the terminal device to communicate, an isolated E-UTRAN function being a function of a base station device or a gateway transferring user data when the base station device is in a first state where connectivity to the core network is lost and/or a second state where a restriction on connectivity to the core network is imposed,
• receiving, from the base station device, a notification message indicating that the base station device is in the first state and/or the second state;
• detach the first PDN connection on the basis of the notification message;
• and
• only when at least permission information indicating that communication based on the isolated E-UTRAN function is permitted is stored,
• initiating an attach procedure by transmitting, to the base station device, an attach request message including at least the permission information.