UE and communication control method for UE

A User Equipment (UE), comprising:

• a controller configured to:
• send a Protocol Data Unit (PDU) session establishment request message,
• start a first timer on a per Single Network Slice Selection Assistance information (S-NSSAI) basis with a first back-off timer value in a case that a first cause value to start the first timer and the first back-off timer value are included in a Protocol Data Unit (PDU) session establishment reject message received from a core network, the S-NSSAI being identified within a Public Land Mobile Network (PLMN),
• start a second timer on a per S-NSSAI and Data Network Name (DNN) basis with a second back-off timer value in a case that a second cause value to start the second timer and the second back-off timer value are included in the PDU session establishment reject message received from the core network, the S-NSSAI being identified within a PLMN,
• start a third timer on a per DNN basis with a third back-off timer value in a case that a third cause value to start the third timer and the third back-off timer value are included in the PDU session establishment reject message received from the core network, the first cause value, the second cause value, and the third cause value being different each other,
• send another PDU session establishment request message in a case that the first cause value to start the first timer and the first back-off timer value indicating zero are included in the PDU session establishment reject message received from the core network,
• send another PDU session establishment request message in a case that the second cause value to start the second timer and the second back-off timer value indicating zero are included in the PDU session establishment reject message received from the core network, and
• send another PDU session establishment request message in a case that the third cause value to start the third timer and the third back-off timer value indicating zero are included in the PDU session establishment reject message received from the core network;
• wherein the first cause value indicates that a specific slice is congested, the second cause value indicates that a specific slice and a DNN are congested, and the third cause value indicates that a DNN is congested.