JP4450738B2 - Communication control device, communication control system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To realize seamless switching between terminals during end-to-end communication in an IP-based mobile communication network. <P>SOLUTION: When the communication opposite party of a communication terminal (#3) is switched from a communication terminal (#1) to a communication terminal (#2), a correspondence table at the time of switching from the communication terminal (#1) to the communication terminal (#2) is used. In this way, a combination of HA1 and RA1 is switched to a combination of HA1 and RA2, a packet 27 becomes a configuration of a packet 37 (RA2, RA2) by referring to the correspondence table in an edge node, and the reception packet 47 (HA2, HA3) is received by the communication terminal (#2). A transmission packet 51 (HA2, HA1) of the communication terminal (#2) becomes a packet 41[RA2, RA3] via a node 17, and a reception packet becomes a reception packet 31 (HA1, HA3) in the same case as a case where the communication terminal (#1) has been an opposite party via a node 21 by referring to the correspondence table in the same way. Thus, switching of the opposite party terminal can be seamlessly performed. <P>COPYRIGHT: (C)2006,JPO&amp;NCIPI

Description

  The present invention relates to a communication control technique for seamless switching between communication terminal devices.

  In a mobile communication network such as a mobile phone system, it is important that communication can be continued even if a communication terminal moves. As a function for that purpose, for example, a mobility management function is provided. The mobility management function always tracks and detects (understands) the current location of the communication terminal so that it can respond to changes in the connection position between the communication terminal and the network due to movement of the communication terminal. It is a function to have a function to transmit properly to the connection position.

  In a next generation mobile communication network, an all-IP in which all data is transmitted and exchanged in the form of IP packets by providing a common IP backbone utilizing IP (Internet Protocol) communication technology constructed by the development of the Internet. It is assumed that the base platform will be built and used. In addition, a so-called call control separation type architecture in which data transmission functions and control functions such as call setting and routing management are clearly separated has been studied. In the architecture described above, the transport layer, which is a lower layer, is dedicated to the function of transmitting data, that is, IP packets, at high speed and efficiently, and functions such as routing (routing) control and traffic control are located in the upper layer of the transport layer. By sharing the configuration and instructing the IP packet routing, resource allocation, and the like from the upper layer to the transport layer, the entire system is increased in speed and efficiency. In the all IP-based platform, it is assumed that control signals such as call control and signaling are also transmitted in the form of IP packets.

  In a mobile communication network, transmission path switching control of a router that transmits IP packets, so-called handover control, while maintaining call connection and session connection in accordance with movement of the position of a communication terminal and change of a base station accommodated thereby Is done. In an all-IP mobile communication network in which all data to a mobile communication terminal is transmitted as IP packets, the data (IP packet) addressed to the own terminal or the partner terminal in communication is appropriately routed as the communication terminal moves. Since the address information to be changed changes, IP address rewrite control is performed following the movement of the terminal. At this time, an IP address (host address) for identifying a communication terminal is distinguished from an IP address (routing address) used for routing, and only the routing address is changed with the host address being a fixed value regardless of the movement of the terminal.

  Specifically, a correspondence table between the host address and the routing address is prepared at an edge node that is located at the edge of the network and is a boundary point where a communication terminal is connected to the network via a wireless base station or the like. With reference to the correspondence table, the host address and the routing address are mutually rewritten (see, for example, Patent Document 1).

  FIG. 8 shows a setting procedure until the communication terminal 207b as a call source sets a call connection with the communication terminal 211b as a communication partner, and the communication terminal 207b can start a session with the communication terminal 211b as a partner. FIG. 5 is a diagram illustrating a basic control method for handover when a counterpart communication terminal moves while maintaining call connection and session thereafter. FIG. 9 is a diagram illustrating a state of address rewriting for an IP packet at the time of handover.

  The communication terminal 207b located closest to the base station (3) 207a in FIG. 8 is connected to the base station (3) 207a via the base station (3) 207a based on a host address that is an IP address representing its own identity before starting communication. The location management control information is sent to the mobility management unit 203 as indicated by an arrow 300. The mobility management unit 203 uses the location management function to transmit the location registration control information from the base station 3, so that the location where the communication terminal 207b is located is indicated by a dashed circle. It is grasped that it is located in the cover area (1) 207 which is a physical range under its jurisdiction. At the same time, the anchor router (AR) 205a to which the base station 207a is connected is associated with the host address of the communication terminal 207b, assigns a routing address as route information to the communication terminal 207b, and is within the circle in FIG. As shown, the routing address is stored in its own routing table, and the routing address is registered in the mobility management unit 203. Similarly, since the communication terminal (# 1) 211b as the communication partner is registered in the mobility management unit 203 via the nearest base station (1) 211a as indicated by an arrow 301, the mobility management unit 203 The location management function recognizes that the communication terminal (# 1) 211b is located in the cover area (2) 211, and the anchor router 205b to which the base station (1) 211a is connected is connected to the communication terminal (# 1) Assign a routing address to 211b, hold it in its own routing table, and register the routing address in the mobility management unit 203 by control information as shown by an arrow 301 in FIG.

  In order for the communication terminal 207b to start communication with the communication terminal 211b, as shown by the arrow 302, first, when the user designates the telephone number of the partner communication terminal 211b by operating the button on the communication terminal 207b, etc. The communication terminal 207b designates the host address of the communication terminal 211b which is the designated communication partner, and sends control information for requesting call setting to the base station 207a having jurisdiction over the coverage area in which it is located. The base station 207a receives the call setting request and sends the call setting request control information 303 including the destination host address to the mobility management unit 203.

  Since the coverage area where the communication terminal (# 1) 211b, which is the call destination, is known in the location registration procedure described above, the mobility management unit 203 knows the base station having jurisdiction over the coverage area, ie, Control information as shown by an arrow 304 is sent to the base station (1) 211a of 8 by the call control function to notify the call, and the base station (1) 211a notifies the communication terminal (# 1) 211b by a thick arrow. Send a call setup request as shown.

  When communication terminal (# 1) 211b makes a call response to base station (1) as indicated by a thick arrow, call connection is established. At this time, in the anchor router 205b to which the base station (1) 211a is connected, the correspondence between the host address and the routing address of the communication terminal 207b that is the call source is registered and held as indicated by the arrow 305.

  Here, the mobility management unit 203 uses the route control function to control the anchor address of the communication terminal (# 1) 211b to the anchor router 205a to which the base station 3 that is the call request source is connected based on the control information indicated by the arrow 306. , The routing address is registered in the destination information of the routing table in the anchor router 205a in association with the host address of the communication terminal (# 1) 211b, as shown in the circle in FIG. 9B. Thereafter, the anchor router 205a refers to the routing table, and sets the source and destination host addresses described in the header portion of the IP packet sent from the communication terminal 207b to the communication terminal (# 1) 211b. As shown in the circle in (c) of FIG. 9, each is written in the routing address registered above. By switching, the IP packet is transferred between the routers in the transport layer based on the routing address, and can be transmitted to the destination communication terminal (# 1) 211b, and the end-to-end call connection is set. It becomes a state and communication can be started.

  As described above, as long as the communication terminal 211b of the other party is located in the cover area (2) 211, the routing address toward the base station (1) 211a can be used via the anchor router 205b. However, if the communication terminal 211b moves to the cover area (3) 215 as indicated by the white arrow in FIG. 8 (in this case, the communication terminal is the same as 211b and has not been changed, but the reference numeral 215b is used for distinction). In the routing address, the IP packet cannot reach the destination communication terminal 215b, and communication cannot be continued. Therefore, when the communication terminal 211b moves to the cover area (3) 125, as indicated by the dotted arrow 307 from the communication terminal 215b, the control information for notifying the movement is sent to the base having jurisdiction over the cover area (3) 215. Send to station (2) 215a.

  In the anchor router 205c to which the base station (2) 215a is connected, a new routing address is assigned to the communication terminal # 1, and the routing address is sent to the mobility management unit 203 by the control information as indicated by the dotted arrow 308 in FIG. Is registered, the mobility management unit 203 transmits the control information as indicated by the dotted arrow 309 to notify the anchor router 205a to which the nearest base station (3) 207a of the communication terminal 207b is connected. . The anchor router 205a updates the information in the routing table as shown in the circle of FIG. 9D, and thereafter, the header portion of the IP packet transmitted from the communication terminal 207b is replaced with the header of FIG. As shown in the circle, the updated routing table is referred to and rewritten to a new routing address, and each router in the transport layer passes through the anchor router 205c to the base station (2) 215a to which the communication terminal 207b is moved. The IP packet is transferred and communication is continued. By this handover control, the routing address of the communication terminal changes, but it is possible to perform uninterrupted communication by guaranteeing the maintenance as continuous communication without depending on the change of the routing address.

  Up to this point, call connection has mainly been described. In conventional voice calls, there is no particular distinction between a call connection and a session. However, in the case of multimedia communication or data communication, the application of the communication terminal is connected on the transmission path established at the end and end after setting the call connection. A session with is set up. This is executed by the application on the communication terminal 207b sending a session setting request to the application on the communication terminal (# 1) 211b via the service management unit 201. As a result, the service management unit 201 can manage and grasp the state of the session.

  In the above description, the position management function, call control function, route control function, and transport layer 205 of the mobility management unit 203 have been mainly described. However, in the next-generation all-IP mobile communication network, a communication terminal in the network The inclusion of session control functions is being considered. This is because it has become necessary to provide functions such as connection control and communication control according to various communication forms, modes, media, etc. from the network due to diversification and sophistication of communication. For example, in the case of making a call to the other party by specifying the quality such as the voice call or the video phone, the quality such as the resolution and bit rate of the video phone, and the terminal capability, a communication terminal that meets these requirements is selected. Functions that are insufficient for end-to-end negotiation, such as address resolution for designation and setting of transmission paths of appropriate quality (call control, route control), need to be realized by the capability of the network.

Therefore, a service management unit 201 is provided to manage and control sessions between communication terminals, and manage the processing and operation of the mobility management unit 203. That is, the service management unit 201 is configured to manage and grasp a communication state including a call connection state and a session state between the communication terminal 207b and the communication terminal 211b.
JP 2004-112727 A

  In an all-IP mobile communication network that transmits all data in IP packets, the source and destination communication terminals are identified by the IP address of the communication terminal. However, the IP address serves both as identification of the communication terminal and route control (routing) in the network. Therefore, when the communication terminal moves and the connection position to the network changes, the communication terminal is uniquely identified. This causes a conflict that the address that should be changed must be changed. That is, with the IP address assigned to the IP packet, it has been a problem that mobility management of the communication terminal is extremely difficult.

  In addition, the above-described conventional technology solves the above-described problem, but is designed only to support the movement of a communication terminal, and the communication terminal that is currently in communication is switched to another communication terminal and is interrupted. The point of continuing communication was not considered. Switching of communication terminals has been realized by managing and controlling communication between communication terminals at a higher layer rather than at the IP packet level.

  Therefore, in the prior art, when switching communication terminals, at the IP packet transmission level, communication is temporarily interrupted / disconnected and a new communication path is set / established with the switching destination communication terminal. It was not guaranteed that there was no break (seamlessness) at the actual data transmission level.

  In addition, since control in the upper layer generally requires more processing time than control in the lower layer, there is a problem that the user feels discontinuity in real-time communication and conversational communication.

  It is an object of the present invention to perform end-to-end communication in an all-IP based mobile communication network that transmits multimedia such as voice and video, text such as mail, and other data all in the form of IP packets. It is to provide a communication control technology that realizes seamless communication terminal switching.

  In the present invention, the mobility management function in the mobile communication network, more specifically, the function of rewriting the IP address from the host address to the routing address at the edge node is also applied to the switching of the communication terminal, so that it is seamless at high speed. Communication terminal switching that can guarantee reliability. Specifically, when the communication terminal of the communication destination is switched from the communication terminal (# 1) to the communication terminal (# 2), the host address of the communication terminal (# 1) is changed to the routing address of the communication terminal (# 2) at the edge node. By preparing a correspondence table to be associated with and rewriting addresses according to this correspondence table, IP packets addressed to the communication terminal (# 1) are transmitted to the communication terminal (# 2).

  According to the present invention, seamless terminal switching can be realized during end-to-end communication in an all-IP based mobile communication network. In particular, since the mobility management function prepared in the all-IP mobile communication network is applied, it is very easy to realize the method of the present invention. In addition, it is a great advantage that switching of communication terminals can be realized only by a very simple device of devising a correspondence table for IP address rewriting.

  In order to follow the high-speed movement of the communication terminal, the address rewriting process at the edge node and the change of the correspondence table to be referred to are generally transmitted and processed in the network at a very high speed, so the same mechanism is used. This guarantees that a very high-speed communication terminal switching process can be realized.

  Furthermore, since the address rewriting process at the IP packet level is used, the communication terminal can continue to send out the IP packet without being aware that the partner communication terminal has been switched. It is guaranteed that the data is reliably transmitted to the switching destination communication terminal. That is, completely seamless communication terminal switching can be realized.

  In addition, the present invention not only realizes seamless switching between different communication terminals, but also a multi-mode that has different wireless access methods such as a cellular method and a wireless LAN even in the same communication terminal. Even when the terminal switches the access method while continuing communication, and the connection destination edge node differs depending on the access method (such as switching from an edge node for mobile phones to an edge node for wireless LAN) It is possible to exert its function.

FIG. 1 is a schematic diagram for explaining the principle of communication control according to the present invention.
In the communication system A, in the network, a correspondence table 23 is created between the host address of the communication terminal that is communicating or connected to the network and the routing address corresponding to the edge node to which the communication terminal is connected. 1 is controlled and managed. The mobility management unit 1 also performs control and management such as rewriting of the correspondence table 23 due to movement of the communication terminal. The correspondence table 23 can be referred to from the edge nodes 13, 15, and 17 to which the communication terminal is connected, and the host address and routing address in the edge nodes 13, 15, and 17 can be rewritten. It can be carried out.

  As shown in FIG. 1, when communication is established between the communication terminal (# 1) (host address = HA1) 3 and the communication terminal (# 3) (host address = HA3) 7, each host A correspondence table 23 of addresses (HA) and routing addresses (RA) is prepared. When an IP packet is sent from the communication terminal (# 3) 7 to the communication terminal (# 1) 3, the host address (IPha) of HA3 is designated as its own terminal address and HA1 is designated as the partner terminal address (27). In the edge node 15, the correspondence table 23 is referred to, and the host addresses (IPha) of the communication terminal (# 3) 7 and the communication terminal (# 1) 3 included in the IP packet are assigned to the corresponding routing addresses (IPra). (HA3 → RA3, HA1 → RA1) is performed and transferred to the IP transport unit 11. The IP transport unit 11 is composed of a group of routers having a function of transferring an IP packet by referring to an IP address, and a communication terminal (# 1) 3 is connected according to a partner terminal address (routing address IPra = RA1). Is transferred to the edge node 13 that has been processed. In the edge node 13, referring to the host address / routing address correspondence table 23, contrary to the above, processing to write back IPra to IPha (RA 3 → HA 3, RA 1 → HA 1) is performed, and IP transport The IP packet received from the unit 11 is sent to the communication terminal (# 1) 3.

  On the other hand, the same applies when an IP packet addressed to the communication terminal (# 3) 7 is transmitted from the communication terminal (# 1) 3. In the edge node 13, the communication terminal (# 1) 3 and the communication are transmitted based on the correspondence table 23. The process of rewriting the IPha of the terminal (# 3) 7 to the corresponding IPra is performed, and the IPra is written back to IPha in the edge node 15 on the communication terminal (# 3) 7 side.

  In this way, the communication terminals transmit and receive IP packets that specify the host address of themselves and the other party, and can communicate without being aware of routing within the network, that is, the current connection position of the other party communication terminal. . Conversely, the network, particularly the transport unit 11, can control and manage the transmission of IP packets using only the routing address.

  When the communication terminal moves and the connected edge node is changed, it is necessary to change the route for transferring the IP packet to the communication terminal. Therefore, a new routing address is assigned to the moved communication terminal so that the communication terminal is routed to the destination edge node, and the correspondence table of the host address and the routing address is updated. The assignment of the new routing address is managed and controlled by the mobility management unit 1, and the updated correspondence table is referred to from the edge node to which the communication terminal that is the communication partner of the moved communication terminal is connected.

  As described above, since the communication terminal performs processing only in the network without being conscious of the change of the routing address accompanying movement, it is free to change the routing address of the communication terminal appropriately and flexible. Processing is possible.

  For example, when switching the communication partner of the communication terminal (# 3) 7 from the communication terminal (# 1) 3 to the communication terminal (# 2) 5, the communication terminal (# 1) 3 indicated by reference numeral 25 → the communication terminal (# 2) A correspondence table for 5 switching is created. More specifically, in the correspondence table 25, the host address of the communication terminal (# 1) 3 before switching is associated with the routing address of the communication terminal (# 2) 5 after switching.

  The address rewriting operation in FIG. 1 will be described. Before the communication terminal is switched, that is, when the communication terminal (# 3) 7 is communicating with the communication terminal (# 1) 3, first, the communication terminal (# 3) In the transmission packet 27 sent from 7 to the edge node 15, HA1 is converted to RA1 and HA3 is converted to RA3 in the edge node 15 (33). The packet 33 is transferred in the IP transport unit 11 according to the RA 1 and reaches the edge node 13. At the edge node 13, RA 1 is rewritten to HA 1 and RA 3 is rewritten to HA 3 with reference to the correspondence table (23), converted into a received packet 43, and received by the communication terminal (# 1) 3. The transmission packet 45 transmitted from the communication terminal (# 1) 3 with the host address HA1 in the opposite direction to the edge node 13 is rewritten into a packet 35, and the edge node 15 stores the correspondence table (23). The address is written back again with reference to the received packet 31 and received by the communication terminal (# 3) 7.

  Here, when the terminal in communication is switched from the communication terminal (# 1) 3 to the communication terminal (# 2) 5, the correspondence table is switched to that indicated by reference numeral 25. As a result, the pair of HA1 and RA1 becomes a pair of HA1 and RA2, and the address of the packet 27 is rewritten as the packet 37 (RA3, RA2) by referring to the correspondence table 25 in the edge node 15. In the IP transport unit 11, the packet 37 is transferred to the edge node 17 to which the communication terminal (# 2) 5 is connected according to RA 2 that is the transmission destination address. When the edge node 17 receives the packet 37, the address is rewritten with reference to the correspondence table (23), and the received packet 47 (HA2, HA3) is received by the communication terminal (# 2) 5.

  The address of the transmission packet 51 (HA2, HA3) of the communication terminal (# 2) 5 is similarly rewritten in the edge node 17 by referring to the correspondence table 23 to become the packet 41 (RA2, RA3). Transferred to the edge node 15, the address is rewritten with reference to the correspondence table (25) in the edge node 15, and the received packet 31 (HA 1, HA 1, HA, It is transmitted to the communication terminal (# 3) 7 as HA3). In this way, the address rewriting and the correspondence table change are automatically executed in the network under the control of the mobility management unit 1 so that the communication terminal (# 3) 7 is the destination terminal. Since it is possible to continue to transmit and receive packets whose host address of the communication partner is HA1, without being aware of the fact that the terminal has been switched, seamless terminal switching can be realized.

  Actually, various forms are conceivable for the communication terminal that performs communication and the connection form of the communication terminal of the switching destination to the network, that is, the relationship with the edge node connected to each communication terminal. For example, 1) When communication terminals (# 1) 3, (# 2) 5, and (# 3) 7 are connected to different edge nodes, 2) communication terminals (# 1) 3, (# 2) 5, (# 3) 7 are all connected to the same edge node 3) Communication terminals (# 1) 3 and (# 2) 5 are the same, (# 3) 7 is connected to a different edge node 4) (# 1) 3 and (# 3) 7 are the same, (# 2) 5 is connected to different edge nodes 5) (# 2) 5 and (# 3) 7 are the same , (# 1) 3 is for different edge nodes.

  In each case, the position and operation where address rewriting is performed are different, but as an example, in the case of the above 3) with reference to FIGS. 2 to 4, that is, communication terminals (# 1) 3 and (# 2 ) 5 is the same, and (# 3) 7 is an operation example when connected to another edge node. In the following, an operation example when the IP packet 27 is transmitted from the communication terminal (# 3) 7 will be described, but the same can be considered for the IP packet transmitted in the reverse direction.

  As shown in FIG. 2, before switching, the correspondence between the host address and the routing address corresponds to the edge node 13 and the edge node 15 respectively connected to the communication terminal (# 1) 3 and the communication terminal (# 3) 7. Tables 57 and 53 are prepared. Based on the correspondence tables 57 and 53, the host node and the routing address are rewritten at each edge node 13 and 15, and the IP packet is transmitted. The IP address 27 of the communication terminal (# 3) 7 (HA1, HA3) (1: IP packet transmission) is rewritten at the edge node 15 based on the correspondence table 53 (2: IP address rewriting). , HA1 is converted to RA-x1 and HA3 is converted to RA-y3. In the IP transport unit 11, the address part is transmitted as a packet 33 having RA-x1 and RA-y3 (3: IP packet transmission), and the edge In the node 13, RA-x1 is converted to HA1 and RA-y3 is converted to HA3 based on the correspondence table 57 (4: IP address write-back). Accordingly, the communication terminal (# 1) 3 receives the packet 43 (HA1, HA3) (5: IP packet reception). In this example, the communication terminal (# 1) 3 is connected to the edge node 13 and the communication terminal (# 3) 7 is connected to the edge node 15.

  Here, the correspondence relationship between the host address and the routing address in the correspondence tables 57 and 53 is the same, and the correspondence table 53 and the one referred to by the edge node 13 are shown as the correspondence table 57. Are stored in the referring edge nodes. That is, the correspondence table 53 is stored in the edge node 15 and the correspondence table 57 is stored in the edge node 13. The mobility management unit 1 manages the correspondence tables 57 and 53 in an integrated manner, and manages and controls them so as to ensure their consistency.

  Next, when the communication terminal (# 3) 7 is switched from the communication terminal (# 1) 3 to the communication terminal (# 2) 5, the user on the communication terminal (# 1) 3 side communicates. The network service management unit 51 is requested to switch the communication terminal used for communication from the communication terminal (# 1) 3 to the communication terminal (# 2) 5, or the communication terminal (# 1) When it is determined that switching from 3 to the communication terminal (# 2) 5 is performed or any terminal switching is determined, as shown in FIG. Terminal switching is instructed (6: terminal switching instruction (# 1 → # 2)).

  In this case, prior to switching, the communication terminal (# 2) 5 must already be connected to the network and registered for location, and its host address and routing address must be managed and registered in the correspondence table 71. If not yet registered, the communication terminal (# 2) 5 is connected to the network, the routing address RA-x2 is assigned to the communication terminal (# 2) 5 by the mobility management unit 1 and the edge node 13, and the host address HA2 Is newly created and set in the correspondence table 71 (7; communication terminal correspondence table setting). At this time, the edge node 13 notifies the mobility management unit 1 of the routing address RA-x2 of the communication terminal (# 2) 5.

  Next, the mobility management unit 1 changes the routing address RA-x1 corresponding to the host address HA1 of the communication terminal (# 1) 3 to the routing address RA-x2 of the communication terminal (# 2) 5. Notify the edge node 15 to which the terminal (# 3) 7 is connected (8: NW side correspondence table rewrite notification).

  Upon receiving the update notification, the edge node 15 updates the entry of the host address HA1 of the communication terminal (# 1) 3 in the correspondence table 63 as shown in the correspondence table 65. Here, the update notification may include control information indicating that the update is temporary or transient accompanying switching of the communication terminal. In this case, the correspondence table 65 is temporary. It can be managed and stored with information indicating that it is. Thereafter, the destination host address HA1 described in the IP packet addressed to the communication terminal (# 1) 3 transmitted from the communication terminal (# 3) 7 is referred to by the edge node 15 with reference to the correspondence table 65. It is changed as packet 37 (RA-x2, RA-y3). Here, since the communication terminal (# 2) 5 is connected to the same edge node 13 as the communication terminal (# 1) 3, the routing addresses RA-x2 and RA-x1 are both in the transport unit 11. The address is controlled so as to be transferred to the edge node 13. Accordingly, this packet 37 is transferred to the edge node 13 as in the case of addressing to the communication terminal (# 1) 3, and the routing address RA as shown in the packet 73 based on the correspondence table 71 in the edge node 13. The IP address is written back from -x2 to the host address HA2 (13), and is transmitted to the communication terminal (# 2) 5 as a packet 47 (14). When the communication terminal switching process is completed, the communication terminal (# 3) 7 recognizes that the communication partner (# 3) 7 has switched to the communication terminal (# 2) 5. When the packet addressed to the communication terminal (# 2) 5 is transmitted, the temporary correspondence table 65 in which the routing address is changed may be deleted. Here, the correspondence table 65 is preferably managed and stored clearly indicating that it is temporary. As a result, processing such as deletion later can be simplified (described later with reference to FIG. 4).

  The mobility management unit 1 makes an entry corresponding to the host address (HA1) of the communication terminal (# 1) 3 with respect to the related edge node, that is, the edge node 15 to which at least the communication terminal (# 3) 7 is connected. Is notified and changed to the routing address (RA-x2) of the communication terminal (# 2) 5.

  As described above, the packet addressed to the communication terminal (# 1) 3 (HA1) transmitted from the communication terminal (# 3) 7 is transmitted to the communication terminal (# 2) 5 (RA). The destination is rewritten to -x2). On the communication terminal (# 2) 5 side, the routing address (RA-x2) is written back to the host address (HA2) of the communication terminal (# 2) 5 with reference to the correspondence table 71.

  Up to this point, the communication terminal switching is in a transitional state, so that the communication terminal (# 3) 7 recognizes that the partner communication terminal has been switched, and sends a packet addressed to the communication terminal (# 2) 5 (HA2). Then, the entry of HA1 in the correspondence table 63 and the correspondence table 65 can be deleted. Note that the edge node 13 on the communication terminal (# 1) 3 / communication terminal (# 2) 5 side does not need to change the correspondence table and perform special processing when the communication terminal is switched.

  Next, resetting after switching will be described with reference to FIG. Up to the above processing, the IP packet transfer path and destination are only temporarily changed by making the host address of the communication terminal (# 1) 3 correspond to the routing address of the communication terminal (# 2) 5. . The service management unit 51 also notifies the communication terminal (# 3) 15 that the communication partner switches from the communication terminal (# 1) 3 to the communication terminal (# 2) 5. Receiving this notification, the communication terminal (# 3) 15 recognizes that the communication partner has been switched, and thereafter designates the packet addressed to the communication terminal (# 2) 5, specifically the host address of the transmission destination HA2. Packet 27 is sent out.

  In such a state, the temporary correspondence table 65 is unnecessary, and conversely, if the correspondence table is held forever, a completely different terminal connected to the edge node 15 can communicate with the communication terminal # 1 (3 ) May cause inconvenience that they are erroneously transferred to the communication terminal (# 2) 5 when calling or transmitting data. Therefore, in order to quickly return to the steady state, as shown in FIG. 4, the mobility management unit 1 resets the correspondence table, specifically, deletes the entry of the communication terminal # 1 or routes the host address HA1. An instruction is given to restore the address to be associated with the address RA-x1 (16: deletion of correspondence table of terminal # 1), and the call connection of the communication terminal (# 1) 3 is released (15: disconnection). Thereafter, address rewriting is performed by referring to the correspondence table between the host address and the routing address between the communication terminal (# 3) 7 and the communication terminal (# 2) 5 as in the state before switching (17: IP Packet transmission, 18: IP address rewriting, 19: IP packet transmission, 20: IP address write-back, 21: IP packet reception).

  The switching destination communication terminal (# 2) 5 may be connected to the network and registered in advance (that is, the correspondence table between HA2 and RA-x2 is managed and registered in the mobility management unit 1 and the edge node 13). When the switching from the communication terminal (# 1) 3 is confirmed, it is connected to the network (that is, the correspondence table between HA2 and RA-x2 is newly created and set in the mobility management unit 1 and the edge node 13) You may do it.

  In addition, in order to reduce the transmission load of control information on the network, the processing load, the storage capacity of the correspondence table at the edge node, each edge node communicates with the communication terminal connected to the edge node and the communication terminal. It is preferable that only the address rewriting correspondence table regarding the other party is notified, managed, and stored. That is, when the communication terminal (# 2) 5 is connected to an edge node different from the communication terminal (# 1) 3, the address rewriting of the edge node to which the communication terminal (# 2) 5 is connected is supported. In the table, there is no entry of the communication terminal (# 3) 7 (HA3) as the communication partner. Therefore, when it is determined that the communication terminal (# 2) 5 communicates with the communication terminal (# 3) 7 by switching the communication terminal, the mobility management unit 1 is connected to the communication terminal (# 2) 5. The edge node is instructed and controlled to create an entry that associates the host address HA3 of the communication terminal (# 3) 7 with the routing address RA-y3.

  The above operation will be described as a communication procedure with reference to FIG. Currently, data transmission is performed between the communication terminal (# 3) 7 and the communication terminal (# 1) 3 (111). Here, when the communication terminal (# 1) 3 switches to the communication terminal (# 2) 5 by a user operation or the like, a terminal switching request signal is sent to the service management unit 51 (113). The service management unit 51 determines whether or not it is necessary to switch the communication terminal based on a terminal switching request signal (113) from the communication terminal or a determination in the network (115). The mobility management unit 1 determines, for example, a route instructed from the service management unit 51 based on the decision of switching of the communication terminal in the service management unit 51 and the ID (including identification information and host address) of the communication terminal before and after switching. In accordance with the setting instruction (117), it is determined that the communication terminal (# 1) 3 which is the communication partner of the communication terminal (# 3) 7 is switched to the communication terminal (# 2) 5, and the address rewrite correspondence table 53 is changed to a new one. The correspondence table 65 is created and controlled so as to be referenced from the edge node of the transport unit. When the change of the correspondence table is completed, the mobility management unit 1 returns a response 121 to the route change instruction to the service management unit 51. Based on the above processing, by changing the address correspondence table, data transmission between the communication terminal (# 3) 7 and the communication terminal (# 2) 5 becomes possible. Next, a session is established between the service management unit 51 and the communication terminal (# 2) 5 (123, 125), and communication and data between the communication terminal (# 3) 7 and the communication terminal (# 2) 5 are established. Transmission is enabled (130), and the communication terminal is switched. The session management unit 51 disconnects the session with the communication terminal (# 1) 3 before switching (131), and releases the communication terminal (# 1) 3 from the communication state. Following or simultaneously with the session establishment with the communication terminal (# 2) 5, the service management unit 51 notifies the communication terminal (# 3) 7 of the communication partner (# 2) by the terminal switching notification (127). ) Notify switching to 5. When the communication terminal (# 3) 7 recognizes that the communication partner has been switched, that is, when the subsequent data is ready to be sent to the communication terminal (# 2) 5, the terminal switching notification is sent to the service management unit 51. (129). From this point onward, the process transitions from the terminal switching to the so-called steady state, and data transfer between the communication terminal (# 3) 7 and the communication terminal (# 2) 5 is established and executed. (133).

  Next, referring to FIG. 5 and FIG. 6, among the examples of the connection forms described above, 1) Communication terminals (# 1) 3, (# 2) 5, and (# 3) 7 are connected to different edge nodes. The processing in the case of being performed will be described more specifically. As shown in FIG. 5, the mobile communication system according to the present embodiment includes a mobility management unit 1, a communication terminal (# 3) 7, a counterpart communication terminal (# 1) 3, a communication terminal (# 2) 5, Edge nodes (EN) 15a, 13a, 17a directly connected to the respective communication terminals 7, 3, 5 respectively. The edge node 15 a has a terminal side routing table 91 and an NW (network) side routing table 93. A transmission packet 27a is sent from the communication terminal (# 3) 7 having the host address HA3 to the communication terminal (# 1) 3 having the host address HA1. At this time, the host side routing table 91 and the NW side routing table 93 are used to rewrite the host addresses HA1 and HA3 included in the packet 27a to the corresponding routing addresses RA1 and RA3 in the edge node 15a (packet 33a). . Then, in the edge node 13a, the address of the packet 33a is rewritten as the packet 43a (HA1, HA3) using the terminal side routing table 97 and the NW side routing table 101, and the communication terminal (# 1) 3 is rewritten. Received. The packet 45a transmitted from the communication terminal (# 1) 3 is rewritten into the packet 35a by using the terminal side routing table 97 and the NW side routing table 101 at the edge node 13a, and further, the edge node 13a. In 15a, the address is rewritten using the terminal side routing table 91 and the NW side routing table 93, and sent as the received packet 31a to the communication terminal (# 3) 7 of the host address HA3. When switching the communication terminal (# 1) 3 to the communication terminal (# 2) 5, the mobility management unit 1 instructs the edge node 15a to rewrite the NW side routing table to 95 (1), and the edge node When the routing table setting (103, 105) to the communication terminal (# 3) 7 is performed for 17a, the route of the packet 27a transmitted from the communication terminal (# 3) 7 to the communication terminal (# 1) 3 is communicated. The route is changed so as to be transferred from the terminal (# 3) 7 to the communication terminal (# 2) 5 (3), and the route from EN3 (15a) to EN1 (13a) is disconnected (4). .

  Thereafter, the exchange of packets between the communication terminal (# 3) 7 and the communication terminal (# 2) 5 is performed between the edge node EN3 (15a) and the edge node EN2 (17a). The terminal side routing table 103 and the NW side routing table 105 of the edge node EN2 (17a), the terminal side routing table 91 of the edge node EN3 (15a), and the rewritten NW side routing table 95 are used as a communication terminal ( # 3) Packets between 7 and the communication terminal (# 2) 5 are exchanged smoothly. FIG. 6 is a diagram illustrating a situation after switching and resetting. Through the exchange shown in FIG. 5, as shown in FIG. 6, the data transmission from the communication terminal (# 3) 7 to the communication terminal (# 1) 3 is not performed, and the communication terminal (# 3) 7 communicates with the communication terminal ( # 2) Communication continues with route to # 5. At this time, the mobility management unit 1 resets the NW side routing table (6). In other words, the table 95 in which the IPha of the NW side routing table is HA1 and IPra is RA2 is deleted, and only the table 95a corresponding to HA2 is used. When the communication terminal (# 3) 7 recognizes that the communication partner has been switched to the communication terminal (# 2) 5, the host address as shown in the transmission packet 27b and the reception packet 31b from the communication terminal (# 3) 7 The HA is changed to designate HA2 instead of HA1. Thereby, the switching and resetting based on the terminal change are completed.

  In the above-described embodiment, the case where the host node and the routing address are converted at the edge node for both the source address and the destination address has been described. However, only the destination address may be converted. . In this case, the effect of simplifying the address rewriting process at the edge node can be obtained. Since it is a destination address that needs to be referred to at a minimum when transferring a packet in the transport unit, and it is not always necessary to refer to a transmission source address, the present invention can be configured even if only the destination address is converted. The function of changing the transmission path to the switching destination communication terminal at the time of switching the communication terminal is not impaired. However, since the packet sent from the switching destination communication terminal # 2 (HA2) is not subject to rewriting at the edge node, the communication terminal # 2 remains the HA2 designated by the communication terminal # 2. Received on # 3. Therefore, when the communication terminal # 3 is switched to the communication terminal of the communication partner, it is configured to be able to receive and process the packet whose transmission source is HA2, or recognize that the communication partner has switched to the communication terminal # 2. Until then, it is necessary to devise such as deferring transmission from communication terminal # 2.

  As described above, according to the communication control technique according to the present embodiment, since the mobility management function prepared in the all-IP mobile communication network is applied, it is very easy to realize terminal switching. In addition, it is a great advantage that switching of communication terminals can be realized by a very simple step of rewriting the IP address correspondence table. Since it is a simple process, it is possible to follow the high-speed movement of the communication terminal. In other words, the address rewriting process at the edge node and the modification of the correspondence table referred to for that process are transmitted and processed in the network at a very high speed. Therefore, using the same mechanism as this is a communication terminal switching process. It guarantees high speed.

  Furthermore, since the address rewriting process at the IP packet level is used, the communication terminal can continue to send out the IP packet without being aware that the partner communication terminal has been switched. It is guaranteed that the data is reliably transmitted to the switching destination communication terminal. That is, completely seamless communication terminal switching can be realized.

  In addition, the present invention not only realizes seamless switching between different communication terminals, but also a multi-mode that has different wireless access methods such as a cellular method and a wireless LAN even in the same communication terminal. In the case of switching the access method while continuing communication with the terminal, when the edge node of the connection destination differs depending on the wireless access method (such as switching from the edge node for mobile phone to the edge node for wireless LAN) It is possible to exert its function. In the above description, this can be realized if the communication terminal # 1 and the communication terminal # 2 are the same communication terminal.

  In the above-described embodiment, the application relating to the portable terminal such as the cellular phone and the PDA has been described. However, application to various home appliances using these communication functions is also possible.

  The present invention can be applied to control technology for electronic devices having various communication terminals and communication functions.

It is the schematic for demonstrating the principle of the communication control technique of this invention. It is a figure which shows the state before switching of the communication terminal in the communication system by embodiment of this invention. It is a figure which shows the state at the time of the switching of the communication terminal in the communication system by this Embodiment. It is a figure which shows the state after switching of the communication terminal in the communication system by this Embodiment. It is a figure which shows the mode at the time of the switching of the communication terminal in the communication system by a present Example. It is a figure which shows the mode after switching and resetting of the communication terminal in the communication system by a present Example. It is a figure which shows the example of a communication procedure in the communication system by a present Example. It is a figure which shows the example of whole structure of the conventional communication system. It is a conceptual diagram of the address rewriting in the conventional communication system.

Explanation of symbols

A ... communication system, 1 ... mobility management unit, 3, 5, 7 ... communication terminal, 13, 15, 17, 21 ... edge node, 23, 25 ... correspondence table.

Claims (13)

Control of communication between at least first to third communication terminals that can be connected to each other in a network, and data transmitted from the first communication terminal at a first edge node connected to the first communication terminal Based on a first address correspondence table holding a correspondence relationship between a host address of a second communication terminal as a destination and a routing address indicating a transfer path for transmitting data to the second communication terminal, at least Control to rewrite the host address of the second communication terminal specified as the destination address in the data packet sent from the first communication terminal to the routing address of the second communication terminal, and follow the movement of the communication terminal The mobile communication system includes a mobility management unit that controls the change of the data transfer path in the network and continues communication. Te,
When the mobility management unit switches the communication partner with the first terminal from the second communication terminal to the third communication terminal without interrupting communication, the mobility management unit performs the first in the first address correspondence table. A mobile communication system, wherein the host address of the second communication terminal is rewritten so as to be associated with the routing address of the third communication terminal. Controls communication between at least first to third communication terminals connectable to each other in a network, and a destination of data transmitted from the first communication terminal at a first edge node connected to the first communication terminal Based on a first address correspondence table that holds a correspondence relationship between a host address of the second communication terminal and a routing address indicating a transfer path for transmitting data to the second communication terminal, Control to rewrite the host address of the second communication terminal specified as the destination address in the data packet transmitted from one communication terminal to the routing address of the second terminal, and follow the movement of the communication terminal Between the application of the communication terminal and the mobility management unit that continues the communication by controlling the change of the data transfer path in the network A mobile communication system comprising a session management unit which controls the session indicating the communication status,
When one of the communication terminals is switched from the second communication terminal to the third communication terminal without interrupting communication with the communication partner with the first communication terminal, the communication terminal switches the communication terminal. Making a request to the session management unit, the session management unit requesting the mobility management unit to control to change a data transmission path based on switching of the communication terminal, and the mobility management unit A mobile communication system, wherein the address correspondence table is rewritten so that the host address of the second communication terminal is associated with the routing address of the third communication terminal.   The first address correspondence table after the rewriting is a correspondence table that is temporarily created when a communication partner is switched from the second communication terminal to the third communication terminal. The mobile communication system according to claim 1 or 2.   A second address correspondence table that holds the correspondence between the host address and routing address of the third communication terminal that is the switching destination is created, and the first rewritten after the switching process of the communication destination terminal is completed. The mobile communication system according to claim 1 or 2, wherein the mobile communication system returns to a steady state by performing control to delete the address correspondence table.   4. The mobile communication system according to claim 3, wherein information indicating that the first address correspondence table after rewriting is temporary is provided and managed and stored.   When the third communication terminal is not connected or unregistered with respect to the network, the routing address corresponding to the second edge node to which the third communication terminal is connected is selected when the communication terminal is switched. 6. The mobile communication system according to claim 1, wherein the mobile communication system is assigned to three communication terminals, and a correspondence table between the host address of the third communication terminal and the routing address is created and set. .   Each of the first and second edge nodes manages and stores only a correspondence table related to a communication terminal connected to the edge node and a counterpart communication terminal communicating with the communication terminal. The mobile communication system according to any one of claims 1 to 6.   Controls communication between at least first to third communication terminals connectable to each other through a network, and allows communication partners with the first communication terminal to communicate with each other from the second communication terminal to the third communication terminal without interrupting communication. A mobility management unit that performs communication management for switching to a host of a second communication terminal that is a destination of data transmitted from the first communication terminal in a first edge node connected to the first communication terminal A host address of the second communication terminal included as a destination address in at least a data packet transmitted from the first communication terminal based on a first address correspondence table that holds a correspondence relationship between an address and a routing address Is changed to the routing address of the second communication terminal, and the communication partner is switched from the second communication terminal to the third communication terminal. When doing so, the communication control device having a mobility manager, wherein the rewriting as to be associated with the routing address of the said first address table with a host address of the second communication terminal third communication terminal. Provided between the communication terminal and the network,
Controls communication between at least first to third communication terminals connectable to each other through a network, and allows communication partners with the first communication terminal to communicate with each other from the second communication terminal to the third communication terminal without interrupting communication. The host address and routing address of the second communication terminal that is at least the transmission destination stored in the first edge node connected to the first communication terminal based on the instruction of the mobility management unit that performs communication management to switch to An address correspondence table that is created from a first address correspondence table that holds a correspondence relationship between the routing address and the routing address corresponding to a host address of the third communication terminal. Node device.   10. The edge node manages and stores only a correspondence table related to a communication terminal connected to the edge node and a counterpart communication terminal communicating with the communication terminal. Edge node device. Between at least the first to third communication terminals that can be connected to each other through the network, the communication partner with the first communication terminal of the transmission source can be transmitted from the second communication terminal to the third communication terminal without interrupting communication. A communication control method for switching to a communication terminal,
In response to a switching request signal from the second communication terminal, the routing is based on a first address correspondence table that holds a correspondence relationship between at least a destination host address and a routing address related to the first communication terminal. A communication control method comprising a step of creating a second address correspondence table in which an address is changed to a routing address corresponding to a host address of the third communication terminal.   Based on the second address correspondence table, at least a host address of the second communication terminal specified as a destination address in a data packet transmitted from the first communication terminal is routed to the second communication terminal. 12. The communication control method according to claim 11, wherein control is performed to rewrite the address, and a destination of a transmission packet from the first communication terminal is changed to the third communication terminal.   The program for making a computer perform the step of Claim 11 or 12.

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