JP4684052B2 - COMMUNICATION SYSTEM, MOBILE TERMINAL DEVICE, AND VOICE HANDOVER METHOD - Google Patents

Description

  The present invention relates to a communication system, a mobile terminal device, and a voice handover method capable of realizing voice handover of a mobile terminal device such as a mobile phone at a low cost between a radio circuit switching network and a radio packet switching network.

  Nowadays, mobile devices such as mobile phones that perform voice communication by a circuit switching method in a wireless circuit switching network are widely used. On the other hand, in a packet switching network, voice communication using VoIP technology (VoIP: Voice over Internet Protocol) is possible by a packet switching method.

  Here, when a mobile phone that performs voice communication using a circuit switching method in a wireless circuit switching network moves to a packet switching network that performs voice communication using a packet switching method, the communication method used differs between the networks. Therefore, voice handover processing becomes difficult.

  Japanese Patent Application Laid-Open No. 2005-27119 (Patent Document 1) discloses a handover method that enables handover processing of a mobile terminal such as a PHS terminal in a VoIP network and allows a user of the mobile terminal to perform seamless communication. It is disclosed.

In the case of this handover method, the handover destination gateway device first acquires the IP address of the handover source gateway device from the gatekeeper device and makes an information call with the handover source gateway device. Then, by acquiring information such as an IP address and an E164 address related to the communication partner of the PHS terminal from the handover source gateway device, and using this information to transmit a Setup message to the communication partner, the handover destination gateway device and the communication partner Establish a communication line between This enables a user of a mobile terminal such as a PHS terminal to perform seamless communication in a VoIP network.
JP 2005-27119 A (pages 9 to 11: FIGS. 5 and 6)

  In recent years, a highly convenient wireless LAN environment (WLAN: Wireless Local Area Network) is being prepared. For this reason, construction of a VoIP system (VoIP: Voice over Internet Protocol) that performs voice communication by a packet switching method using this WLAN environment is being promoted, and between different networks such as the wireless circuit switching network and the packet switching network. Realization of the handover process is strongly desired.

  However, in the case of the handover method disclosed in Patent Document 1, since the gateway device has the main control function of the handover process, it is necessary to provide this function in all existing gateway devices. In addition, in order to perform handover processing between different networks such as the wireless circuit switching network and the packet switching network, it is necessary to develop a gateway device provided with the function for each network. For this reason, the installation cost and development cost of the said function increase, and there exists a problem that service realization cost becomes high as a whole.

  The present invention has been made in view of the above problems, and a communication system, a mobile terminal device, and a voice handover method capable of realizing voice handover processing between different types of networks such as a radio circuit switched network and a packet switched network with an inexpensive configuration. The purpose is to provide.

  In order to achieve the above object, the present invention provides a communication system including a mobile terminal device and a gateway device for connecting a voice call at least on the radio circuit switched network side, a mobile terminal device used therefor, and a communication method. .

In the present invention, the mobile terminal device performs communication corresponding to a radio circuit switching network and voice communication corresponding to a radio packet switching network for performing voice communication corresponding to the radio circuit switching network through the gateway device. a wireless packet-switched network communication means, at least in busy, the a movement detecting means for detecting the movement of each networks wireless circuit switched network and the wireless packet switched network, the wireless packet-switched network by the movement detecting means When a movement from the wireless circuit switching network to the wireless circuit switching network is detected, a call is made with the mobile terminal device designated as the destination via the wireless circuit switching network communication means, and based on the arrival of this call, The voice reception address of the gateway device with which the mobile terminal device is communicating is detected, and this voice reception address is used as the communication for the wireless packet switching network. A handover processing unit for transmitting to the voice communication device serving as the communication partner via the wireless packet switching network, and switching of the communication network in the voice communication device serving as the communication partner based on the voice reception address. And a network selection determining unit that switches the wireless packet switching network communication means to the wireless circuit switching network communication means in synchronization .

  As a result, on the side of the voice communication device serving as the communication partner, the communication destination can be switched based on the transmitted voice reception address, so that the mobile terminal device is moving from the radio packet switching network to the radio circuit switching network. Even in this case, voice communication can be continuously performed.

  Further, according to the present invention, since the message can be transmitted in the same direction as the moving direction of the mobile terminal device, the wireless packet switching network and the wireless circuit switching network are wirelessly connected in a very narrow area. It is possible to move to the wireless circuit switching network after completing all processing necessary for the handover processing on the packet switching network side. For this reason, stable handover processing can be realized.

  In the above invention, the electric field strength detection means detects the electric field strength of a base station provided on the wireless circuit switching network and the electric field strength of an access point provided on the wireless packet switching network. May be.

  Then, when it is detected by the electric field strength detecting means that the electric field strength of the base station is lowered and the electric field strength of the access point is raised, the mobile terminal device transmits the radio signal from the radio circuit switching network. When the mobile terminal detects that the mobile station is moving to the packet switching network, and the electric field strength detecting means detects that the electric field strength of the base station is increased and the electric field strength of the access point is decreased, the mobile terminal A device detects that it is moving from the wireless packet switched network to the wireless circuit switched network. Thereby, the movement state of the mobile terminal apparatus between each network can be detected accurately.

  According to the present invention, in a communication system including a mobile terminal device for performing a voice call and a call control device for controlling communication connection to the mobile terminal device, different types of wireless circuit switching network and wireless packet switching network are used. Voice handover processing between networks can be realized with an inexpensive configuration.

[First embodiment]
(Overall system configuration)
A first embodiment of the present invention will be described with reference to the drawings. FIG. 1 is an explanatory diagram showing a schematic configuration of a communication system according to the present embodiment.

  In the communication system according to the present embodiment, as shown in FIG. 1, a call control device 1 (SIP server device = SIP: Session Initiation Protocol) is provided as a core (core) for voice communication by a packet switching method. Call based on SIP (Session Initiation Protocol) between the switching network 2 (IP network) and the radio circuit switching network 6 that performs voice communication by a circuit switching method between the mobile terminal device 3a such as a mobile phone or a PHS phone A WLAN packet switching network 4 (WLAN packet switching network: WLAN: Wireless Local Area) that connects to each other via a media gateway device 5 (MGW device) that performs control and performs voice communication with the packet switching network 2 by a packet switching method. Network) to each other via the router device 7.

  The core packet switching network 2 includes a radio circuit switching network 6 in which another mobile terminal device 3b performs voice communication, and a subscriber telephone network 9 in which a fixed telephone 8 performs voice communication (= general public network: PSTN: Public Switched Telephone Network) is connected via the MGW apparatus 5.

  Similarly, in the packet switching network 2 serving as the core, the WLAN packet switching network 4 in which other mobile terminal devices 3b perform voice communication, and the Internet 11 in which the personal computer device 10 performs voice communication are respectively connected to the router device 7. Connected through.

(Configuration of call control device)
As shown in FIG. 2, the call control device 1 is a network having a physical network interface, a device driver corresponding to the physical network interface, a network control function such as a dial-up function, and a basic protocol stack (TCP / UDP / IP, etc.) Call control messages are transmitted / received between the interface 21 (network I / F) and the mobile terminal device 3a, etc., and this call control message is transmitted to the mobile terminal device 3b, etc., which is the destination, to make / receive calls And a call control unit 22 for processing.

  The call control device 1 also includes a registration database 25 (registration DB) for storing location information and connection status of each user, and a location registration processing unit 23 that performs location registration processing for each user. .

  In such a call control device 1, the call control unit 22 controls to register connection state information indicating the connection state of each user in the registration database 25, and forwards the position information of each user to the position registration processing unit 23. It has become.

(Configuration of mobile terminal device)
As shown in FIG. 3, the mobile terminal device 3a (and the mobile terminal device 3b) performs voice communication using the packet switching method with the CSR-IF 31 that is an interface for the radio circuit switching network 6 that performs voice communication using the circuit switching method. It has two interfaces with the PSR-IF 32 that is an interface for the packet switching network 2 and the WLAN packet switching network 4.

  Each of the interfaces 31 and 32 includes a physical network interface, a device driver corresponding to the physical network interface, a network control function (NCU) such as a dial-up function, and a basic protocol stack (TCP / UDP / IP or the like).

  In addition, the mobile terminal device 3a includes a network selection determination unit 33 that selects an optimum interface among the interfaces 31 and 32 based on user preference, communication cost, communication quality (electric field strength), and the like, and a call control message. Is transmitted / received between the call control device 1 or the mobile terminal device 3b as a communication partner, and performs a registration / call / call processing, etc., and a heterogeneous type such as a wireless circuit switching network and a packet switching network. A handover processing unit 38 that performs voice handover processing between networks, and a media transmission / reception unit 35 that transmits and receives voice data between the mobile terminal device 3b and the like of the communication partner.

  Further, the mobile terminal device 3a includes an input / output device 36 that is an audio input / output interface including an audio terminal to which a microphone unit, a speaker unit, and the like are connected, a driver, a software interface, an AD / DA conversion unit, and the like. It includes a codec processing unit 37 that converts data transferred from the input / output device 36 and the media transmission / reception unit 35 into a format that is optimal for the corresponding module and communication partner (codec conversion processing).

  The network selection determination unit 33 is a module that switches between CSR-IF31 and PSR-IF32 in synchronization with switching of a communication network on the voice communication device side that is a communication partner for handover processing. In the handover process, the interfaces 31 and 32 are temporarily brought into the driving state at the same time, and the location registration is designated to the call control unit 34.

  The handover processing unit 38 has a function of movement detection means for detecting movement between the networks of the radio circuit switching network 6 and the WLAN packet switching network 4 at least during a call, and in the handover process, the mobile terminal device 3a and the field strength of the access point 40 provided in the WLAN packet switching network 4 shown in FIG. 1 and the field strength of the base station 41 provided in the mobile terminal device 3a and the radio circuit switching network 6 are constantly monitored. ing.

  Then, when the electric field strength of the base station 41 decreases and the electric field strength of the access point 40 increases, the handover processing unit 38 moves the mobile terminal device 3a from the wireless circuit switching network 6 to the WLAN packet switching network 4. And register the location with the call control device 1. On the other hand, when the electric field strength of the base station 41 is increased and the electric field strength of the access point 40 is decreased, the handover processing unit 38 causes the mobile terminal device 3a to change from the WLAN packet switching network 4 to the wireless circuit switching network 6. It judges that it is moving and executes the handover process.

  FIG. 4 shows a specific timing example of the handover process in the handover processing unit 38.

  As shown in FIG. 4, the communication area by the access point 40 of the WLAN packet switching network 4 and the communication area by the base station 41 of the wireless circuit switching network 6 overlap, and the communication area of each network overlaps When the mobile terminal device 3a is located in the middle of the mobile terminal device 3a, when the mobile terminal device 3a moves to the WLAN packet switching network 4 side, the electric field strength of the access point 40 increases and the electric field strength of the base station 41 decreases. Become. In this case, the handover processing unit 38 determines that the mobile terminal device 3a is moving from the area of the wireless circuit switching network 6 to the area of the WLAN packet switching network 4, and registers the location with the call control device 1. And the handover process is executed.

  Further, when the mobile terminal device 3a is located in the middle of the range where the communication areas of the networks overlap, if the mobile terminal device 3a moves to the wireless circuit switching network 6 side, the electric field strength of the base station 41 is As a result, the electric field strength of the access point 40 decreases. In this case, the handover processing unit 38 determines that the mobile terminal device 3a has moved from the area of the WLAN packet switching network 4 to the area of the radio circuit switching network 6, and cancels the location registration with respect to the call control device 1. And the handover process is executed.

  In the present embodiment, by detecting the electric field strength of the access point 40 and the base station 41 in this way on the mobile terminal device 3a side, movement between networks can be constantly monitored, and the level of electric field strength increases. It is determined that the mobile terminal device 3a is moving to the other network, and the handover process is executed.

(Overview of handover processing)
In the communication system of such an embodiment, the call control device 1 holds a voice reception address corresponding to each interface of the CSR-IF 31 and the PSR-IF 32 of the mobile terminal device 3a. When the mobile terminal device 3a moves from the wireless circuit switching network 6 to the WLAN packet switching network 4, the mobile terminal device 3a performs location registration with respect to the call control device 1, and the mobile terminal device 3a performs wireless circuit switching from the WLAN packet switching network 4. When moving to the network 6, location registration is performed with respect to the call control device 1 via the MGW. As a result, the call control device 1 can centrally grasp the movement of the mobile terminal device 3a between the networks. The call control device 1 also grasps the state of the call as the mobile terminal device 3a moves between networks.

  When the mobile terminal device 3a detects movement between networks during a call, the mobile terminal device 3a starts handover processing. In this handover process, the call control device 1 mediates exchange of each SDP information (SDP: Session Description Protocol) of the mobile terminal device 3a and the mobile terminal device 3b that is the communication partner of the mobile terminal device 3a in this example. And do it. This SDP information includes the IP address / port number at which each mobile terminal device 3a, 3b receives a voice packet, codec information, and the like.

(Handover process when moving to WLAN packet switching network)
FIG. 5 shows a schematic diagram of the handover process of the communication system of the first embodiment when the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4.

  In FIG. 5, the mobile terminal device 3a (MN) sets the electric field strength for the WLAN packet switching network 4 and the radio circuit switching network 6 as described above during a call with the mobile terminal device 3b (CN) that is a communication partner. It is detected that the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4 by means such as detection.

  Then, a transmission packet including a voice reception address and a port number used in the WLAN packet switching network 4 currently performing communication is formed, and this is transmitted via the call control device 1 as shown in step S111 of FIG. The data is transmitted to the mobile terminal device 3b that is the communication partner.

  The mobile terminal device 3b that has received the transmission packet switches the communication destination from the MGW device 5 to the mobile terminal device 3a based on the voice reception address and the port number included in the transmission packet, as shown in step S112. As a result, communication using the WLAN packet switching network 4 of the mobile terminal device 3a and the mobile terminal device 3b is started.

  When communication using the WLAN packet switching network 4 is started, the mobile terminal device 3a communicates with the mobile terminal device 3b formed via the wireless circuit switching network 6 as shown in step S113. Disconnect the line. As a result, the handover process when the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4 is completed.

(Handover processing when moving to a wireless circuit switched network)
Next, FIG. 6 shows a schematic diagram of the handover process of the communication system of the first embodiment when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6.

  In FIG. 6, the mobile terminal device 3a (MN) sets the electric field strength for the WLAN packet switching network 4 and the wireless circuit switching network 6 as described above during a call with the mobile terminal device 3b (CN) that is a communication partner. When detecting that the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6 by means such as detecting, the mobile terminal via the CSR-IF 31 as shown in step S121 The device 3a is designated as the destination and a call is made.

  As a result, a call from the mobile terminal device 3a arrives at the mobile terminal device 3a via the MGW device 5 of the radio circuit switching network 6 (= that the call originated by itself) Become).

  Next, based on this incoming call, the mobile terminal device 3a forms a transmission packet including route information such as the voice reception address of the MGW device 5 with which the mobile terminal device 3a is communicating, and sends this to step S122. As shown, the PSR-IF 32 is used to transmit from the WLAN packet switching network 4 via the call control device 1 to the mobile terminal device 3b serving as a communication partner.

  The mobile terminal device 3b that has received this transmission packet switches the communication destination from the mobile terminal device 3a to the MGW device 5, as shown in step S123, based on the voice reception address included in the transmission packet. Thereby, communication using the radio circuit switching network 6 of the mobile terminal device 3a and the mobile terminal device 3b is started, and handover is performed when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the radio circuit switching network 6. The process ends.

(Handover process flow of mobile terminal device)
The flowchart of FIG. 7 shows the flow of handover processing in such a mobile terminal device 3a.

  In the flowchart of FIG. 7, when it is detected in step S131 that communication is being performed with the mobile terminal device 3b, the call control unit 34 of the mobile terminal device 3a moves through the wireless circuit switching network 6 in step S132. It is determined whether or not communication with the terminal device 3b is being performed, and whether or not communication with the mobile terminal device 3b is being performed via the WLAN packet switching network 4 is determined in step S139. If it is determined that the mobile terminal device 3b is communicating with the mobile terminal device 3b via the wireless circuit switched network 6, the process proceeds to step S133, and the mobile terminal device 3b is determined to be communicating with the mobile terminal device 3b via the WLAN packet switched network 4. If so, the process proceeds to step S140.

  In step S133 and step S140, the call control unit 34 of the mobile terminal device 3a moves the mobile terminal device 3a from the wireless circuit switching network 6 to the WLAN packet switching network 4 based on the electric field strength for each of the networks 4 and 6 described above. It is determined whether or not the mobile terminal apparatus 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6. If it is determined that the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4, the process proceeds to step S134, and the mobile terminal device 3a is transferred from the WLAN packet switching network 4 to the wireless circuit switching network 4. If it is determined that the mobile network has moved to the exchange network 6, the process proceeds to step S141.

  When it is determined that the mobile terminal device 3a has moved from the wireless circuit switching network 6 to the WLAN packet switching network 4 and the process proceeds to step S134, it is used in the WLAN packet switching network 4 that is currently communicating. A transmission packet including the voice reception address and the port number is formed, and in step S135, the transmission packet is transmitted to the mobile terminal device 3b which is a communication partner via the call control device 1.

  The mobile terminal device 3b that has received the transmission packet switches the communication destination from the MGW device 5 to the mobile terminal device 3a based on the voice reception address and the port number included in the transmission packet, and the switching of the communication destination is completed. A response signal indicating that it has been transmitted is transmitted to the mobile terminal device 3a. As a result, communication using the WLAN packet switching network 4 of the mobile terminal device 3a and the mobile terminal device 3b is started.

  Next, in step S136 and step S138 of the flowchart of FIG. 7, the call control unit 34 of the mobile terminal device 3a determines whether or not the response signal is returned from the mobile terminal device 3b within a predetermined time. . If the response signal is returned from the mobile terminal device 3b within a predetermined time, the call control unit 34 of the mobile terminal device 3a proceeds to step S137 and is formed via the wireless circuit switching network 6. The communication line with the mobile terminal device 3b is disconnected. As a result, the handover process when the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4 is completed.

  If the response signal is not returned from the mobile terminal device 3b within a predetermined time, the call control unit 34 of the mobile terminal device 3a determines that a time-out has occurred, proceeds to step S148, and performs predetermined error processing. Execute.

  Next, when it is determined in step S140 that the mobile terminal device 3a has moved from the WLAN packet switching network 4 to the wireless circuit switching network 6, the process proceeds to step S141. The voice reception address and the like of the mobile terminal device 3b that is performing communication are acquired, and the process proceeds to step S142.

  In step S142, the call control unit 34 of the mobile terminal device 3a makes a call via the CSR-IF 31 with the mobile terminal device 3a as a transmission destination. As a result, a call from the mobile terminal device 3a arrives at the mobile terminal device 3a via the MGW device 5 of the wireless circuit switching network 6.

  Next, in step S143, the call control unit 34 of the mobile terminal device 3a transmits a transmission packet including route information such as the voice reception address of the MGW device 5 with which the mobile terminal device 3a is communicating based on the incoming call. Is transmitted from the WLAN packet switching network 4 to the mobile terminal device 3b as the communication partner via the call control device 1 in step S144.

  The mobile terminal device 3b that has received this transmission packet switches the communication destination from the mobile terminal device 3a to the MGW device 5 based on the voice reception address included in the transmission packet. Thereby, communication using the radio circuit switching network 6 of the mobile terminal device 3a and the mobile terminal device 3b is started.

  Next, when switching the communication path, the mobile terminal apparatus 3b serving as the communication partner transmits a response signal indicating that the switching of the communication path is completed to the mobile terminal apparatus 3a. In step S145 and step S147, the call control unit 34 of the mobile terminal device 3a determines whether or not the response signal is returned from the mobile terminal device 3b within a predetermined time. If the response signal is returned from the mobile terminal device 3b within a predetermined time, the call control unit 34 of the mobile terminal device 3a proceeds to step S146 and is formed via the WLAN packet switching network 4. The communication line with the mobile terminal device 3b is disconnected. As a result, the handover process when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6 is completed.

  If the response signal is not returned from the mobile terminal device 3b within a predetermined time, the call control unit 34 of the mobile terminal device 3a determines that a time-out has occurred, proceeds to step S148, and performs predetermined error processing. Execute.

(Effect of embodiment)
As is clear from the above description, the communication system according to the present embodiment is configured so that the mobile terminal device 3a transmits a WLAN packet from the wireless circuit switching network 6 during a call between the mobile terminal device 3a and the mobile terminal device 3b that is the communication partner. When movement to the switching network 4 is detected, the mobile terminal device 3a forms a transmission packet including the voice reception address and port number used in the WLAN packet switching network 4 that is currently communicating, To the mobile terminal device 3b.

  The mobile terminal device 3b that has received this transmission packet switches the communication destination from the MGW device 5 to the mobile terminal device 3a based on the voice reception address and the port number included in the transmission packet, so that the mobile terminal device 3a The handover process when moving from the circuit switched network 6 to the WLAN packet switched network 4 is completed.

  Further, during the call, when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6, the mobile terminal device 3a makes a call specifying the mobile terminal device 3a as a destination. Do. As a result, a call from the mobile terminal device 3a arrives at the mobile terminal device 3a via the MGW device 5 of the wireless circuit switching network 6.

  Based on this incoming call, the mobile terminal device 3a forms a transmission packet including route information such as the voice reception address of the MGW device 5 with which the mobile terminal device 3a is communicating, and transmits this packet from the WLAN packet switching network 4. The data is transmitted to the mobile terminal device 3b as a communication partner via the call control device 1.

  The mobile terminal device 3b that receives the transmission packet switches the communication destination from the mobile terminal device 3a to the MGW device 5 based on the voice reception address included in the transmission packet, so that the mobile terminal device 3a The handover process when moving from 4 to the wireless circuit switched network 6 is completed.

  As described above, the communication system according to the present embodiment performs handover processing mainly using the mobile terminal devices (the mobile terminal device 3a and the mobile terminal device 3b). Without adding a function, a handover function between different networks can be realized using a standard function of the existing call control device 1. Therefore, a communication system that realizes handover processing between different types of networks can be provided at low cost.

[Second Embodiment]
Next, a communication system according to a second embodiment of the present invention will be described. In the communication system of the above-described embodiment, when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6, the mobile terminal device 3a itself (the mobile By receiving the incoming call to the terminal device 3a), the voice reception address in the wireless circuit switching network 6 is detected and notified to the mobile terminal device 3b of the communication partner.

  On the other hand, in the communication system of this embodiment, when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6, the mobile terminal device 3a can communicate with itself via the WLAN packet switching network 4. By making a call to itself (the mobile terminal device 3a), a voice reception address in the wireless circuit switching network 6 is detected and notified to the mobile terminal device 3b of the communication partner.

  In the above-described embodiment and the second embodiment, the operation is the same as when the mobile terminal device 3a is moving from the wireless circuit switching network 6 to the WLAN packet switching network 4, and the mobile terminal device 3a Only the operation when moving from the WLAN packet switching network 4 to the wireless circuit switching network 6 is different. Therefore, only the operation when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6 will be described below, and redundant description will be omitted.

(Handover process when moving to a radio circuit switched network in the second embodiment)
FIG. 8 shows a schematic diagram of a handover process when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6 in the communication system of the second embodiment. In FIG. 8, the mobile terminal device 3a (MN) sets the electric field strength for the WLAN packet switching network 4 and the radio circuit switching network 6 as described above during a call with the mobile terminal device 3b (CN) which is a communication partner. By detecting that the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6, the mobile terminal device 3a is designated as the destination, and the WLAN packet switching network 4 is Make a call via. As a result, a call from the mobile terminal device 3a arrives at the mobile terminal device 3a via the WLAN packet switching network 4 (= your own call will arrive at itself).

  At this time, the mobile terminal device 3a recognizes that the incoming call is an incoming call via its own WLAN packet switching network 4, and that the incoming call other than its own call is in handover. For that reason, the incoming call is rejected.

  Next, based on this incoming call, the mobile terminal device 3a forms a transmission packet including route information such as a voice reception address of the MGW device 5 with which the mobile terminal device 3a is communicating, and performs WLAN packet exchange The data is transmitted from the network 4 via the call control device 1 to the mobile terminal device 3b that is a communication partner.

  The mobile terminal device 3b that has received this transmission packet switches the communication destination from the mobile terminal device 3a to the MGW device 5 based on the voice reception address included in the transmission packet. Thereby, communication using the radio circuit switching network 6 of the mobile terminal device 3a and the mobile terminal device 3b is started, and handover is performed when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the radio circuit switching network 6. The process ends.

(Effect of the second embodiment)
As is clear from the above description, in the communication system of the second embodiment, when the mobile terminal device 3a is moving from the WLAN packet switching network 4 to the wireless circuit switching network 6, the mobile terminal device 3a By making an incoming call to itself (the mobile terminal device 3a) via the switching network 4, a voice reception address in the wireless circuit switching network 6 is detected and notified to the mobile terminal device 3b of the communication partner.

  As a result, the same effect as that of the above-described embodiment can be obtained, and since the message can be transmitted in the same direction as the moving direction of the mobile terminal device 3a, the WLAN packet switching network 4 and the wireless circuit switching network 6 are When the WLAN packet switching network 4 is in contact with a small area, all the processing necessary for the handover processing is completed before moving to the radio circuit switching network 6. For this reason, stable handover processing can be realized.

It is a figure which shows an example of the network structure of the communication system used as embodiment to which this invention is applied. It is a block diagram of a call control device provided in the communication system of the embodiment. It is a block diagram of a mobile terminal device used in the communication system of the embodiment. It is a figure for demonstrating the detection operation | movement of the network used as the movement destination of the mobile terminal device used for the delivery system of embodiment. FIG. 4 is a schematic diagram for explaining a handover process executed when a mobile terminal apparatus is moving from a radio circuit switching network to a WLAN packet switching network in the communication system according to the embodiment. FIG. 4 is a schematic diagram for explaining a handover process executed when a mobile terminal apparatus moves from a WLAN packet switching network to a wireless circuit switching network in the communication system according to the embodiment. It is a flowchart for demonstrating the hand-over process between the heterogeneous networks in the communication system used as embodiment. 7 is a schematic diagram for explaining a handover process executed when a mobile terminal apparatus moves from a WLAN packet switching network to a wireless circuit switching network in a communication system according to a second embodiment. FIG.

Explanation of symbols

1 ... Call control device
2 ... Packet switched network
3a… Mobile terminal device
3b… Mobile terminal device
4 ... WLAN packet switching network
5 ... Media gateway device (MGW device)
6 ... Wireless network
7 ... Router device
8 ... landline telephone
9 ... Subscriber telephone network (PSTN network)
10 ... Personal computer equipment
11 ... Internet
21 ... Network interface
22 ... Call controller
23… Location registration processing part
25… Registration database
31 ... Interface for WLAN packet switching network
32… Interface for wireless circuit switching network
33 ... Network selection judgment part
34 ... Call controller
35 ... Media transceiver
36 ... Input / output devices
37 ... Codec processing section
38 ... Handover processing section

Claims (3)

A mobile terminal device;
A gateway device for connecting a voice call at least on the wireless circuit switching network side;
The mobile terminal device
A communication means for wireless circuit switching network for performing voice communication corresponding to the wireless circuit switching network;
A communication means for wireless packet switching network for performing voice communication corresponding to the wireless packet switching network;
Movement detecting means for detecting movement between each of the wireless circuit switched network and the wireless packet switched network at least during a call;
When movement from the wireless packet switching network to the wireless circuit switching network is detected by the movement detecting means , a call is made with the mobile terminal device designated as the destination via the wireless circuit switching network communication means. In addition, based on the incoming call, the voice reception address of the gateway device with which the mobile terminal device is communicating is detected, and the voice reception address is detected using the wireless packet switching network communication means. A handover processing unit for transmitting to the voice communication device as the communication partner via a network;
A network selection determination unit for switching from the wireless packet switching network communication means to the wireless circuit switching network communication means in synchronization with switching of the communication network in the voice communication device as the communication partner based on the voice reception address; communication system that characterized the. A communication means for wireless circuit switching network for performing voice communication corresponding to the wireless circuit switching network;
A communication means for wireless packet switching network for performing voice communication corresponding to the wireless packet switching network;
Movement detecting means for detecting movement between each of the wireless circuit switched network and the wireless packet switched network at least during a call;
When movement from the wireless packet switching network to the wireless circuit switching network is detected by the movement detecting means , a call is made with the mobile terminal device designated as the destination via the wireless circuit switching network communication means. In addition, based on the incoming call, the voice reception address of the gateway device with which the mobile terminal device is communicating is detected, and the voice reception address is detected using the wireless packet switching network communication means. A handover processing unit for transmitting to the voice communication device as the communication partner via a network;
A network selection determination unit for switching from the wireless packet switching network communication means to the wireless circuit switching network communication means in synchronization with switching of the communication network in the voice communication device as the communication partner based on the voice reception address; mobile terminal said. A communication means for wireless circuit switching network for performing voice communication corresponding to the wireless circuit switching network;
A communication means for wireless packet switching network for performing voice communication corresponding to the wireless packet switching network;
A voice handover method using a mobile terminal device comprising movement detecting means for detecting movement between each of the wireless circuit switched network and the wireless packet switched network at least during a call,
At least during a call, the movement detecting means detects movement from the wireless packet switched network to the wireless circuit switched network; and
In the step, the step of performing the radio when the movement from the packet switched network to the wireless circuit switched network is detected, the call specifying the mobile terminal device via the communication means for the wireless circuit switched network to the destination When,
In the mobile terminal device, detecting the voice reception address of the gateway device with which the mobile terminal device is communicating based on the incoming call;
Transmitting the voice reception address to the voice communication device as the communication partner via the wireless packet switching network using the wireless packet switching network communication means ;
Switching from the wireless packet switching network communication means to the wireless circuit switching network communication means in synchronization with switching of the communication network in the voice communication device as the communication partner based on the voice reception address. A voice handover method characterized by the above.

Images