Network node and communication method
View Patent ↗A network node whereby there is no loss of communication quality and the call interruption time can be shortened to continue communication even when the codec used by one terminal during communication changes. In MSC/MGW for forwarding data between two terminals when one of the two terminals performing communication in a first network transfers to a second network different from the first network, a codec detector detects both a first codec used by one terminal in the first network and a second codec used by one terminal in the second network. When the first codec is a codec having a mode compatible with the second codec, an RTP payload generator switches the codec of data transmitted from one terminal to the compatible mode of the first codec, thereby generating data for the other terminal, and a transmitter transmits the data for the other terminal to the other terminal.
1. A communication system, comprising:
a network node;
a first terminal which supports a first codec; and
a second terminal,
wherein the first codec supports a codec A compatible mode and a codec A non-compatible mode, the first codec being a new codec and codec A having a dedicated payload format,
the codec A compatible mode is compatible with a second codec and the codec A non-compatible mode is non-compatible with the second codec, the second codec being a legacy codec,
the first terminal and the second terminal negotiate the codec A non-compatible mode in a session negotiation to select the codec A non-compatible mode to be used for the communication between the first terminal and the second terminal when the communication starts, and
when the network node detects that the negotiated codec A non-compatible mode of the first terminal is switched to the codec A compatible mode or the second codec in the communication between the first terminal and the second terminal, the network node transmits a signal for the second terminal to switch the negotiated codec A non-compatible mode of the second terminal to the codec A compatible mode by a payload format of the first codec, and the second terminal switches the negotiated codec A non-compatible mode of the second terminal to the codec A compatible mode based on the signal.
2. The communication system according to claim 1 ,
wherein when the network node detects that the negotiated codec A non-compatible mode of the first terminal is switched to a third codec, the third codec being not any of the codec A compatible mode and the second codec in the communication after the codec A non-compatible mode is selected by the session negotiation, the first terminal and the second terminal re-negotiate a codec to be used for the communication.
3. The communication system according to claim 1 ,
wherein the payload format is common for the codec A compatible mode and the codec A non-compatible mode.
4. The communication system according to claim 1 ,
wherein the signal is transmitted by a Real-time Transport Protocol (RTP).
5. The communication system according to claim 1 ,
wherein the signal is included in a Session Description Protocol (SDP) offer.
6. The communication terminal, comprising:
a negotiator that negotiates a codec A non-compatible mode to be used for communication with a first terminal when the communication starts, wherein codec A has a dedicated payload format;
a receiver that receives a signal for switching the negotiated codec A non-compatible mode of the terminal to a codec A compatible mode by a payload format of the first codec; and
a generator that switches the negotiated codec A non-compatible mode to the codec A compatible mode based on the signal,
wherein the codec A compatible mode and the codec A non-compatible mode are supported by a first codec which is a new codec,
the second codec is a legacy codec, and
the codec A compatible mode is compatible with the second codec and the codec A non-compatible mode is non-compatible with the second codec.
7. The communication terminal according to claim 6 , further comprising:
a transmitter that transmits a data which is encoded using the codec A compatible mode by using the payload format of the first codec.
8. The communication terminal according to claim 6 ,
wherein the negotiator that selects a preferential mode, which is one of the codec A compatible mode and the codec A non-compatible mode, based on information described in a Session Description Protocol (SDP) offer and answers or information incorporated beforehand in software.
9. The communication terminal according to claim 6 ,
wherein the payload format is common for the codec A compatible mode and the codec A non-compatible mode.
10. The communication terminal according to claim 6 ,
wherein the signal is transmitted by a Real-time Transport Protocol (RTP).
11. The communication terminal according to claim 6 ,
wherein the signal is included in a Session Description Protocol (SDP) offer.
12. The communication terminal according to claim 6 ,
wherein the signal is transmitted from a network node.
13. The communication method, comprising:
negotiating a codec A non-compatible mode to be used for communication with a first terminal when the communication starts, wherein codec A has a dedicated payload format;
receiving a signal for switching the negotiated codec A non-compatible atoll mode of the terminal to a codec A compatible mode by a payload format of the first codec; and
switching the negotiated codec A non-compatible mode to the codec A compatible mode based on the signal,
wherein the codec A compatible mode and the codec A non-compatible mode are supported by a first codec which is a new codec,
the second codec is a legacy codec, and
the codec A compatible mode is compatible with the second codec and the codec A non-compatible mode is non-compatible with the second codec.
14. The communication method according to claim 13 , further comprising:
transmitting a data that is encoded using the codec A compatible mode by using the payload format of the first codec.
15. The communication method according to claim 13 , further comprising:
selecting a preferential mode, which is one of the codec A compatible mode and the codec A non-compatible mode, based on information described in a Session Description Protocol (SDP) offer and answers or information incorporated beforehand in software.
16. The communication method according to claim 13 ,
wherein the payload format is common for the codec A compatible mode and the codec A non-compatible mode.
17. The communication method according to claim 13 ,
wherein the signal is transmitted by a Real-time Transport Protocol (RTP).
18. The communication method according to claim 13 ,
wherein the signal is included in a Session Description Protocol (SDP) offer.
19. The communication method according to claim 13 ,
wherein the signal is transmitted from a network node.
20. The communication method in a communication system, including at least a first terminal which supports a first codec, and a second terminal, wherein the first codec supports a codec A compatible mode and a codec A non-compatible mode, the first codec being a new codec, codec A has a dedicated payload format, the codec A compatible mode is compatible with a second codec and the codec A non-compatible mode is non-compatible with the second codec, the second codec being a legacy codec, the method comprising:
negotiating the codec A non-compatible mode in a session negotiation to select the codec A non-compatible mode to be used for the communication between the first terminal and the second terminal when the communication starts;
when detecting the negotiated codec A non-compatible mode of the first terminal is switched from the codec A non-compatible mode to the codec A compatible mode or the second codec in the communication between the first terminal and the second terminal, transmitting a signal for the second terminal to switch the negotiated codec A non-compatible mode of the second terminal to the codec A compatible mode by a payload format of the first codec; and
switching the negotiated codec A non-compatible mode of the second terminal to the codec A compatible mode based on the signal.