Radio terminal, processor and communication method

A radio terminal comprising:

• a controller configured to control traffic steering between an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and a Wireless Local Area Network (WLAN), wherein
• the controller is configured to control traffic steering from the E-UTRAN to the WLAN or from the WLAN to the E-UTRAN according to at least one of a first scheme and a second scheme,
• the traffic steering means switching traffic of the radio terminal from one network to another network,
• in the first scheme, the controller is configured to control the traffic steering with assistance of the E-UTRAN,
• in the second scheme, the controller is configured to control the traffic steering in response to an instruction from the E-UTRAN,
• the radio terminal further comprises a receiver configured to receive, from the E-UTRAN, first assistance information to be used to determine whether the radio terminal executes the traffic steering in the first scheme, the first assistance information being broadcasted by the E-UTRAN,
• the receiver is further configured to receive, from the E-UTRAN, WLAN configuration information including a timer value indicating a period over which the WLAN configuration information is held, and
• the controller is configured to:
• activate a timer corresponding to the timer value when the radio terminal transitions from an RRC connected mode to an RRC idle mode;
• hold the WLAN configuration information until the timer expires;
• and
• discard the WLAN configuration information upon expiration of the timer, wherein
• the first scheme is a scheme in which the radio terminal starts the control of the traffic steering by using the first assistance information, based on radio qualities in the WLAN and the E-UTRAN, even without an instruction from the E-UTRAN, and
• the second scheme is a scheme in which the radio terminal starts the control of the traffic steering with a traffic steering instruction from the E-UTRAN as a trigger.

A processor configured to control a radio terminal, wherein the processor is configured to perform a first process of controlling traffic steering between an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and a Wireless Local Area Network (WLAN),

• in the first process,
• the processor is configured to control traffic steering from the E-UTRAN to the WLAN or from the WLAN to the E-UTRAN according to at least one of a first scheme and a second scheme,
• the traffic steering means switching traffic of the radio terminal from one network to another network,
• in the first scheme, the processor is configured to control the traffic steering with the assistance of the E-UTRAN,
• in the second scheme, the processor is configured to control the traffic steering in response to an instruction from the E-UTRAN,
• the processor is configured to perform:
• a second process of receiving, from the E-UTRAN, first assistance information to be used to determine whether the radio terminal executes the traffic steering in the first scheme, the first assistance information being broadcasted by the E-UTRAN;
• a third process of receiving, from the E-UTRAN, WLAN configuration information including a timer value indicating a period over which the WLAN configuration information is held;
• and
• a fourth process of:
• activating a timer corresponding to the timer value when the radio terminal transitions from an RRC connected mode to an RRC idle mode;
• holding the WLAN configuration information until the timer expires;
• and
• discarding the WLAN configuration information upon expiration of the timer, wherein
• the processor is further configured to stop controlling the traffic steering according to the first scheme in response to reception of the instruction.

A communication method comprising:

• controlling, by a radio terminal, traffic steering between an Evolved-Universal Terrestrial Radio Access Network (E-UTRAN) and a Wireless Local Area Network (WLAN), wherein
• in the controlling, the radio terminal controls traffic steering from the E-UTRAN to the WLAN or from the WLAN to the E-UTRAN according to at least one of a first scheme and a second scheme,
• the traffic steering means switching traffic of the radio terminal from one network to another network,
• in the first scheme, the radio terminal controls the traffic steering with assistance of the E-UTRAN,
• in the second scheme, the radio terminal controls the traffic steering in response to an instruction from the E-UTRAN,
• the communication method further comprises:
• broadcasting, by the E-UTRAN, first assistance information to be used to determine whether the radio terminal executes the traffic steering in the first scheme;
• and
• receiving, by the radio terminal, the first assistance information from the E-UTRAN, the communication method further comprises:
• transmitting, by the E-UTRAN, WLAN configuration information including a timer value indicating a period over which the WLAN configuration information is held;
• receiving, by the radio terminal, the WLAN configuration information and the timer value from the E-UTRAN;
• activating, by the radio terminal, a timer corresponding to the timer value when the radio terminal transitions from an RRC connected mode to an RRC idle mode;
• holding, by the radio terminal, the WLAN configuration information until the timer expires;
• and
• discarding, by the radio terminal, the WLAN configuration information upon expiration of the timer, and wherein
• the communication method further comprises:
• stopping, by the radio terminal, the control of the traffic steering according to the first scheme in response to reception of the instruction.