Gateway device, mobile terminal, mobile communication method, and program

1. A gateway device configured to connect a packet transfer device on a mobile high-speed network and a radio network controller on a mobile circuit-switched network via an IP multimedia subsystem (IMS) network, the gateway device comprising:

a reception device configured to receive a request signal for changing a bit rate of audio from the packet transfer device;

one or more processing devices configured to convert an audio compressed-and-encoded bit stream, stored in a packet transmitted from the packet transfer device or the radio network controller, into a bit rate requested in the request signal when the gateway device receives the request signal for changing the bit rate of audio at the transmission and reception device; and

a transmission device configured to transmit the converted bit stream to the radio network controller or the packet transfer device.

2. The gateway device according to claim 1 , wherein

when the reception device of the gateway device receives from the packet transfer device the request signal for changing a bit rate of audio that is transmitted from a mobile terminal connected to the mobile high-speed network, the one or more processing devices converts the audio compressed-and-encoded bit stream stored in the packet transmitted from the packet transfer device into the bit rate transmittable and receivable by the mobile terminal connected to the radio network controller and the transmission device transmits the converted bit stream to the radio network controller.

3. The gateway device according to claim 2 , wherein

the reception device receives the request signal transmitted from the packet transfer device via a session control device on the IMS network.

4. The gateway device according to claim 2 , wherein

when the reception device receives the packet transfer request signal, the transmission device notifies the packet transfer device or the session control device of an acknowledgement.

5. The gateway device according to claim 1 , wherein when the reception device of the gateway device receives from the packet transfer device the request signal for changing the bit rate of audio that is transmitted to a mobile terminal connected to the mobile high-speed network, the one or more processing devices converts the audio compressed-and-encoded bit stream transmitted from the radio network controller into the bit rate requested in the request signal and the transmission device transmits the converted bit stream to the packet transfer device.

6. The gateway device according to claim 5 , wherein

the reception device receives the packet transfer request signal transmitted from the packet transfer device via a session control device on the IMS network.

7. The gateway device according to claim 5 , wherein

when the reception device receives the packet transfer request signal, the transmission device notifies the packet transfer device or the session control device of an acknowledgement.

8. The gateway device according to claim 1 , wherein

the reception device receives the request signal transmitted from the packet transfer device via a session control device on the IMS network.

9. The gateway device according to claim 8 , wherein

when the reception device receives the packet transfer request signal, the transmission device notifies the packet transfer device or the session control device of an acknowledgement.

10. The gateway device according to claim 1 , wherein

when the reception device receives the request signal, the transmission device notifies the packet transfer device or the session control device of an acknowledgement.

11. The gateway device according to claim 1 , wherein

when congestion is caused in the mobile high-speed network, the request signal is transmitted by a mobile terminal connected to the mobile high-speed network.

12. The gateway device according to claim 11 , wherein

an occurrence of congestion in the mobile high-speed network is detected by an eNodeB device on the mobile high-speed network.

13. The gateway device according to claim 12 , wherein

the eNodeB device uses explicit congestion notification-congestion experienced (ECN-CE) information to notify a mobile terminal of the occurrence of congestion.

14. The gateway device according to claim 1 , wherein

the request signal is encoded in a codec mode request (CMR) format that meets the requirements defined in Request for Comment (RFC) 3267.

15. The gateway device according to claim 1 , wherein

the mobile high-speed network including the packet transfer device from which the gateway device receives the request signal comprises long term evolution (LTE) or evolved packet core (EPC).

16. A mobile communication system, comprising:

a gateway device that connects a packet transfer device on a mobile high-speed network and a radio network controller on a mobile circuit-switched network via an IP multimedia subsystem (IMS) network; and

a first mobile terminal, connected to the mobile high-speed network and executing audio communication with a second mobile terminal connected to the mobile circuit-switched network via the gateway device, wherein

when the gateway device receives from the packet transfer device a request signal for changing a bit rate of audio, the gateway device converts an audio compressed-and-encoded bit stream, stored in a packet transmitted from the packet transfer device or the radio network controller, into a bit rate requested in the request signal and transmits the converted bit stream to the radio network controller or the packet transfer device, and

upon receiving the converted bit stream, the packet transfer device or the radio network controller forwards the converted bit stream to the first mobile terminal or the second mobile terminal.

17. A mobile communication method, comprising:

connecting, by a gateway device, a packet transfer device on a mobile high-speed network and a radio network controller on a mobile circuit-switched network via an IP multimedia subsystem (IMS) network;

receiving, by the gateway device from the packet transfer device, a request signal for changing a bit rate of audio;

converting, by one or more processing devices of the gateway device, an audio compressed-and-encoded bit stream, stored in a packet transmitted from the packet transfer device or the radio network controller, into a bit rate requested in the request signal; and

transmitting the converted bit stream to the radio network controller or the packet transfer device.

18. The mobile communication method according to claim 17 ,

wherein when the gateway device receives from the packet transfer device the request signal for changing the bit rate of audio that is transmitted to a mobile terminal connected to the mobile high-speed network, the audio compressed-and-encoded bit stream transmitted from the radio network controller is converted, by the one or more processing devices of the gateway device, into the bit rate requested in the request signal, and the converted bit stream is transmitted to the packet transfer device.

19. The mobile communication method according to claim 17 ,

wherein when the gateway device receives from the packet transfer device the request signal for changing the bit rate of audio that is transmitted from a mobile terminal connected to the mobile high-speed network, the audio compressed-and-encoded bit stream stored in the packet transmitted from the packet transfer device is converted, by the one or more processing devices of the gateway device, into the bit rate that is transmittable and receivable by a mobile terminal connected to the radio network controller, and the converted bit stream is transmitted by the gateway device to the radio network controller.