Gateway apparatus and method and communication system

1. A first gateway apparatus that is connected to a packet transfer apparatus provided on a mobile packet network and is connected to a second gateway apparatus provided on a mobile circuit switched network to perform voice communication therebetween, said first gateway apparatus comprising

a conversion section that includes:

a receiver that receives at least one of a first call control signal and a first packet that has voice data stored therein in a first predetermined protocol or first payload format from said packet transfer apparatus on said mobile packet network;

a transmitter that transmits at least one of a second call control signal and a second packet that has voice data stored therein in a second predetermined protocol or second payload format to said packet transfer apparatus;

an analysis unit that decides whether a conversion of at least one of said first call control signal, and said first predetermined protocol or said first payload format, is necessary, and decides whether a conversion of at least one of a call control signal from said second gateway apparatus into said second call control signal, and a voice signal from said second gateway apparatus into said second packet of a protocol corresponding to said packet transfer apparatus, is necessary; and

a converter that converts at least one of said first call control signal and said first predetermined protocol or said first payload format, when said analysis unit decides that a conversion thereof is necessary, into a protocol being same as a circuit switched protocol which is used when a radio network controller (RNC) on said mobile circuit switched network connects to said second gateway apparatus, for output to said second gateway apparatus, wherein

said converter receives, from said second gateway apparatus, at least one of a call control signal that uses a protocol being same as a protocol which is used when said second gateway apparatus outputs to said RNC, and said voice signal that uses said same protocol, and converts at least one protocol of said call control signal and said voice signal received, for output to said packet transfer apparatus on said mobile packet network,

wherein said second gateway apparatus connected to said RNC interconnects said mobile circuit switched network and an IMS (IP Multimedia Subsystem) network,

wherein said first gateway apparatus and said second gateway apparatus interconnect a first terminal connected to said packet transfer apparatus provided on said mobile packet network and a second terminal connected to said IMS network,

wherein said second gateway apparatus is configured to receive location information about said second terminal to determine whether or not an address of a packet to be transmitted from or received by said second gateway apparatus via said IMS network to or from said second terminal is changed according to movement of said second terminal, said second gateway apparatus controlling to change the address of said packet to be transmitted to or received from said IMS network side for switching of a destination or source route of said packet, when it is determined that the address of said packet to be transmitted to or received from said second terminal via said IMS network is changed according to movement of said second terminal,

wherein said second gateway apparatus is configured to convert a signal from said IMS network to said circuit switched protocol that is used for supply to said RNC provided on said mobile circuit switched network and transfer the converted signal to said first gateway apparatus,

wherein, when said analysis unit decides that no conversion is needed, said converter is configured to receive a circuit switching protocol frame from said second gateway apparatus and to packetize said circuit switching protocol frame into said second packet, while, when said analysis unit decides conversion is necessary, said converter is further configured to, on reception of a conversion instruction on a per channel basis from said analysis unit, convert said circuit switching protocol frame from said second gateway apparatus into a packet format of a protocol corresponding to said packet transfer apparatus, on a per channel basis, according to said conversion instruction,

said transmitter transmitting said second packet to said packet transfer apparatus.

2. The first gateway apparatus according to claim 1 , wherein said conversion section further comprises

an audio transcoder unit that converts an audio compression encoding scheme of a voice signal.

3. The first gateway apparatus according to claim 1 , wherein said conversion section further comprises

a security processing unit that strengthens a security function in order to exchange a packet with said mobile packet network.

4. The first gateway apparatus according to claim 1 , wherein said mobile packet network comprises at least one of LTE (Long Term Evolution), EPC (Evolved Packet Core), Home NodeB, and Home eNodeB.

5. The first gateway apparatus according to claim 1 , wherein said second gateway apparatus further comprises

a circuit switching equipment.

6. A gateway method by a first gateway apparatus that is connected to a packet transfer apparatus provided on a mobile packet network and is connected to a second gateway apparatus provided on a mobile circuit-switched network to achieve voice communication therebetween, said method comprising:

receiving at least one of a first call control signal and a first packet that has voice data stored therein in a first predetermined protocol or first payload format from said packet transfer apparatus on said mobile packet network;

transmitting at least one of a second call control signal and a second packet that has voice data stored therein in a second predetermined protocol or second payload format to said packet transfer apparatus;

deciding whether a conversion of at least one said first call control signal, and said predetermined first protocol or said first payload format, is necessary;

deciding whether a conversion of at least one of a call control signal from said second gateway apparatus into said second call control signal, and a voice signal from said second gateway apparatus into said second packet of a protocol corresponding to said packet transfer apparatus, is necessary; and

converting at least one of said first call control signal and said first predetermined protocol or said first payload format, when deciding that a conversion thereof is necessary, into a protocol being same as a circuit switched protocol which is used when a radio network controller (RNC) on said mobile circuit switched network connects to said second gateway apparatus, for output to said second gateway apparatus, said method further comprising:

receiving, from said second gateway apparatus, at least one of a call control signal that uses a protocol being same as a protocol which is used when said second gateway apparatus outputs to said RNC, and said voice signal that uses said same protocol; and

converting at least one protocol of said call control signal and said voice signal received, for output to said packet transfer apparatus on said mobile packet network,

wherein said second gateway apparatus connected to said RNC interconnects said mobile circuit switched network and an IMS (IP Multimedia Subsystem) network,

wherein said first gateway apparatus and said second gateway apparatus interconnect a first terminal connected to said packet transfer apparatus provided on said mobile packet network and a second terminal connected to said IMS network,

wherein said second gateway apparatus is configured to receive location information about said second terminal to determine whether or not an address of a packet to be transmitted from or received by said second gateway apparatus via said IMS network to or from said second terminal is changed according to movement of said second terminal, said second gateway apparatus controlling to change the address of said packet to be transmitted to or received from said IMS network side for switching of a destination or source route of said packet, when it is determined that the address of said packet to be transmitted to or received from said second terminal via said IMS network is changed according to movement of said second terminal,

wherein said second gateway apparatus converts a signal from said IMS network to said circuit switched protocol that is used for supply to said RNC provided on said mobile circuit switched network and transfers the converted signal to said first gateway apparatus,

wherein said method further comprises:

when it is decided by said first gateway apparatus that no conversion is needed, receiving a circuit switching protocol frame from said second gateway apparatus and packetizing said circuit switching protocol frame into said second packet, while,

when it is decided by said first gateway apparatus decides that conversion is necessary, converting said circuit switching protocol frame from said second gateway apparatus into a packet format of a protocol corresponding to said packet transfer apparatus, on a per channel basis; and

transmitting said packet to said second packet transfer apparatus.

7. The gateway method according to claim 6 , wherein said second gateway apparatus further comprises

a circuit switching equipment.

8. A communication system, comprising:

a packet transfer apparatus provided on a mobile packet network;

a second gateway apparatus provided on a mobile circuit-switched network; and

a first gateway apparatus that is connected to said packet transfer apparatus and is connected to said second gateway apparatus to achieve voice communication therebetween, wherein said first gateway apparatus comprises a conversion section that includes:

a receiver that receives at least one of a first call control signal and a first packet that has voice data stored therein in a first predetermined protocol or first payload format from said packet transfer apparatus on said mobile packet network;

a transmitter that transmits at least one of a second call control signal and a second packet that has voice data stored therein in a second predetermined protocol or second payload format to said packet transfer apparatus;

an analysis unit that decides whether a conversion of at least one of said first call control signal, and said first predetermined protocol or said first payload format, is necessary, and decides whether a conversion of at least one of a call control signal from said second gateway apparatus into said second call control signal, and a voice signal from said second gateway apparatus into said second packet of a protocol corresponding to said packet transfer apparatus, is necessary; and

a converter that converts at least one of said first call control signal and said first predetermined protocol or said first payload format, when said analysis unit decides that a conversion thereof is necessary, into a protocol being same as a circuit switched protocol which is used when a radio network controller (RNC) on said mobile circuit switched network connects to said second gateway apparatus, for output to said second gateway apparatus, wherein

said converter receives, from said second gateway apparatus, at least one of a call control signal that uses a protocol being same as a protocol which is used when said second gateway apparatus outputs to said RNC, and said voice signal that uses said same protocol, and converts at least one protocol of said call control signal and said voice signal received, for output to said packet transfer apparatus on said mobile packet network,

wherein said second gateway apparatus connected to said RNC interconnects said mobile circuit switched network and an IMS (IP Multimedia Subsystem) network,

wherein said first gateway apparatus and said second gateway apparatus interconnect a first terminal connected to said packet transfer apparatus provided on said mobile packet network and a second terminal connected to said IMS network,

wherein said second gateway apparatus is configured to receive location information about said second terminal to determine whether or not an address of a packet to be transmitted from or received by said second gateway apparatus via said IMS network to or from said second terminal is changed according to movement of said second terminal, said second gateway apparatus controlling to change the address of said packet to be transmitted to or received from said IMS network side for switching of a destination or source route of said packet, when it is determined that the address of said packet to be transmitted to or received from said second terminal via said IMS network is changed according to movement of said second terminal,

wherein, when said analysis unit decides that no conversion is needed, said converter is configured to receive a circuit switching protocol frame from said second gateway apparatus and to packetize said circuit switching protocol frame into said second packet, while, when said analysis unit decides conversion is necessary, said converter is further configured to, on reception of a conversion instruction on a per channel basis from said analysis unit, convert said circuit switching protocol frame from said second gateway apparatus into a packet format of a protocol corresponding to said packet transfer apparatus, on a per channel basis, according to said conversion instruction,

said transmitter transmitting said second packet to said packet transfer apparatus.

9. The communication system according to claim 8 , wherein said second gateway apparatus further comprises

a circuit switching equipment.

10. The gateway method according to claim 6 , comprising converting an audio compression-encoding scheme for a voice signal.

11. The gateway method according to claim 6 , comprising enhancing a security function for exchange of a packet with said mobile packet network.

12. A second gateway apparatus, wherein said second gateway apparatus is connected to a radio network controller (RNC) and a first gateway apparatus provided on a mobile circuit switched network and connected to an IMS (IP Multimedia Subsystem) network, said first gateway apparatus being connected to a packet transfer apparatus provided on a mobile packet network and configured to perform protocol conversion between said mobile circuit switched network and said mobile packet network,

wherein said second gateway apparatus is configured to convert a signal from said IMS network to a circuit switched protocol that is used for supply to said RNC and transfer the converted signal to said RNC and said first gateway apparatus,

wherein said second gateway apparatus is configured to convert a signal of said circuit switched protocol from said RNC or said first gateway apparatus to a SIP (Session Initiation Protocol) or SDP (Session Description Protocol) signal and transfer the converted signal to said IMS network, and

wherein said second gateway apparatus is configured to receive location information about said second terminal to determine whether or not an address of a packet to be transmitted from or received by said second gateway apparatus via said IMS network to or from said second terminal is changed according to movement of said second terminal, said second gateway apparatus controlling to change the address of said packet to be transmitted to or received from said IMS network side for switching of a destination or source route of said packet, when it is determined that the address of said packet to be transmitted to or received from said IMS network side is changed according to movement of said second terminal.

13. The first gateway apparatus according to claim 1 , wherein said second gateway apparatus is configured to hold a sequence number of a last packet transmitted to said IMS network side and to control a sequence number of said packet to be transmitted to said IMS network side to be changed continuously from said last packet, when the address of said packet is changed.

14. The gateway method according to claim 6 , wherein said second gateway apparatus is configured to hold a sequence number of a last packet transmitted to said IMS network side and to control a sequence number of said packet to be transmitted to said IMS network side to be changed continuously from said last packet, when the address of said packet is changed.

15. The communication system according to claim 8 , wherein said second gateway apparatus is configured to hold a sequence number of a last packet transmitted to said IMS network side and to control a sequence number of said packet to be transmitted to said IMS network side to be changed continuously from said last packet, when the address of said packet is changed.

16. The second gateway apparatus according to claim 12 , wherein said second gateway apparatus is configured to hold a sequence number of a last packet transmitted to said IMS network side and to control a sequence number of said packet to be transmitted to said IMS network side to be changed continuously from said last packet, when the address of said packet is changed.