Wireless communication system, base station, mobile station, and method of wireless communication

1. A base station comprising:

a memory; and

a processor coupled to the memory and configured to:

transmit, when a state transition of a mobile station, which causes a state of the mobile station to transfer from a first state to a second state, is performed, a first message of a first control signal to the mobile station, the first control signal controlling a communication between the mobile station and the base station, and

simultaneously transmit, when a second state transition, which causes the state of the mobile station to transfer from the second state to a third state, is performed, a second message of the first control signal and a third message of a second control signal different from the first control signal to the mobile station, the second control signal controlling a communication between the mobile station and a core network.

2. The base station according to claim 1 , wherein the second message transmitted simultaneously with the third message in the second state transition includes indication information indicating a transition to the third state.

3. The base station according to claim 2 , wherein the processor is further configured to:

receive, from the mobile station, the first message including request information requesting the indication information in the first state transition, and

simultaneously transmit the second message including the indication information and the third message to the mobile station based on the request information in the second state transition.

4. The base station according to claim 1 , wherein

the first control signal is a Radio Resource Control (RRC) message, and

the second control signal is a Non-Access Startum (NAS) message.

5. The base station according to claim 1 , wherein

the first state is a RRC IDLE state,

the second state is a RRC CONNECTED state, and

the third state is a RRC INACTIVE state.

6. A mobile station comprising:

a memory; and

a processor coupled to the memory and configured to:

receive a first message of a first control signal, which causes a state of the mobile station to transfer from a first state to a second state, from a base station when a state transition is performed, the first control signal controlling a communication between the mobile station and the base station, and

simultaneously receive, when a second state transition, which causes the state of the mobile station to transfer from the second state to a third state, is performed, a second message of the first control signal and a third message of a second control signal different from the first control signal from the base station, the second control signal controlling a communication between the mobile station and a core network.

7. The mobile station according to claim 6 , wherein

the first control signal is a Radio Resource Control (RRC) message, and

the second control signal is a Non-Access Startum (NAS) message.

8. A wireless communication system comprising a first wireless communication apparatus and a second wireless communication apparatus,

the first wireless communication apparatus including:

a memory; and

a processor coupled to the memory and configured to:

transmit a first message of a first control signal to the second wireless communication apparatus when a state transition of the second wireless communication apparatus, which causes a state of the second wireless communication apparatus to transfer from a first state to a second state, is performed, the first control signal controlling a communication between the first wireless communication apparatus and the second wireless communication apparatus, and

simultaneously transmit, when a second state transition, which causes the state of the second wireless communication apparatus to transfer from the second state to a third state, is performed, a second message of the first control signal and a third message of a second control signal different from the first control signal to the second wireless communication apparatus, the second control signal controlling a communication between the second wireless communication apparatus and a core network.

9. The wireless communication system according to claim 8 , wherein

the first control signal is a Radio Resource Control (RRC) message, and

the second control signal is a Non-Access Startum (NAS) message.

10. A method of wireless communication executed by a wireless communication system including a first wireless communication apparatus and a second wireless communication apparatus, the method comprising:

transmitting a first message of a first control signal to the second wireless communication apparatus, which causes a state of the second wireless communication apparatus to transfer from a first state to a second state, when a state transition of the second wireless communication apparatus is performed, by the first wireless communication apparatus; the first control signal controlling a communication between the first wireless communication apparatus and the second wireless communication apparatus, and

simultaneously transmitting, when a second state transition, which causes the state of the second wireless communication apparatus to transfer from the second state to a third state, is performed, a second message of the first control signal and a third message of a second control signal different from the first control signal to the second wireless communication apparatus, the second control signal controlling a communication between the second wireless communication apparatus and a core network.

11. The method of wireless communication according to claim 10 , wherein

the first control signal is a Radio Resource Control (RRC) message, and

the second control signal is a Non-Access Startum (NAS) message.