JP5654380B2 - Circuit switching apparatus and incoming call control method - Google Patents

Description

  The present invention relates to a circuit switching device and an incoming call control method, and more particularly to a circuit switching device and an incoming call control method for performing incoming processing for a mobile communication terminal.

  In order to cope with a rapid increase in data traffic and an increase in content capacity, LTE (Long Term Evolution) is being introduced for the purpose of speeding up, low delay, and improving frequency efficiency. In LTE, it is difficult to introduce voice (Voice over Internet Protocol; VoIP) service at an early stage due to the necessity of introducing IMS (IP Multimedia Subsystem). Therefore, introduction of a method for performing a CS-FB (CS-Fallback) operation at the time of voice outgoing / incoming calls is underway (see, for example, Non-Patent Document 1 and Non-Patent Document 2).

The CS-FB uses a 3G-CS (Circuit Switching) domain for voice service by switching from using the communication service by the LTE network to using the 3G (3rd Generation) network at the time of voice call. It is a mechanism for providing. This CS-FB will be described with reference to FIG.
Referring to FIG. 10, this system includes an MSC / VLR 1 having a function of a mobile switching center (MSC) in a 3G network and a function of a register (Visitor Location Register; VLR) for temporarily holding a subscriber profile. Corresponding to a base station controller (Radio Network Controller; hereinafter abbreviated as RNC) 2 provided corresponding to this MSC / VLR1, an MME (Mobility Management Entity) 3 functioning as an exchange in the LTE network, and MME3 And an eNodeB 4 provided. A communication service provided by this system can be used by a mobile communication terminal 5 such as a mobile phone.

  The MSC / VLR 1 performs incoming processing when there is a call from an unillustrated source, that is, an incoming call. Further, the MSC / VLR 1 is a mobile communication located in a 3G network area corresponding to a base station control device under its control among subscriber profiles stored in an unillustrated HLR (Home Location Register). Holds the subscriber profile for the terminal. By confirming this subscriber profile, it can be determined whether the mobile communication terminal is located in the 3G network or the LTE network.

The RNC 2 has a function of realizing a 3G network area in the 3G network by controlling a radio base station (not shown). The eNodeB 4 has a function of realizing an LTE network area in the LTE network.
The mobile communication terminal 5 can perform communication using LTE when located in the LTE network area, and can perform communication using 3G network when located in the 3G network area. .

  In the communication system of FIG. 10, when the mobile communication terminal 5 is located in the LTE network area and uses data communication, when a voice call is received from another communication terminal (not shown) to the mobile communication terminal 5 (S101). Then, a call is made from the MSC / VLR 1 to the mobile communication terminal 5 located in the LTE network area via the MME 3 (S102, S103). The mobile communication terminal 5 that has received the call identifies that it is an incoming voice service by CS, and returns a response to the MME 3 (S104). Thereafter, in order to switch the radio from the LTE network to the 3G network (HandOver from the LTE network to the 3G network), a radio switching instruction is transmitted from the MME 3 to the eNodeB 4 (S105).

Thus, after the radio switching from the LTE network to the 3G network is performed, a response from the mobile communication terminal 5 to the call is transmitted to the MSC / VLR 1 (S106). All subsequent processing is performed in the MSC / VLR1.
The above operation will be further described with reference to FIG. FIG. 11 is a sequence diagram showing processing upon arrival in the communication system of FIG. In FIG. 11, when a mobile communication terminal (MT) 5 is located in the LTE network area and uses data communication, a voice call from another communication terminal to the mobile communication terminal 5 occurs (S101). The mobile communication terminal 5 located in the LTE network area is called via the MSC / VLR1, MME3, and eNodeB4 (S102, S103a, S103b). The mobile communication terminal 5 that has received the call returns a response to the MME 3 via the eNodeB 4 (S104a, S104b). Thereafter, a radio switching instruction is transmitted from the MME 3 to the eNodeB 4 (S105).

  After the wireless switching from the LTE network to the 3G network is performed, a response from the mobile communication terminal 5 is transmitted to the MSC / VLR 1 via the RNC 2 (S106a, S106b). Thereafter, existing processing is performed, and a voice call is performed between a communication terminal (not shown) and the MT 5.

TANAKA Taketsuma et al. “CS Fallback function to realize cooperation between LTE and 3G circuit switching service” NTT DOCOMO Technical Journal VOL. 17 NO. 3, [online], October 2009, NTT DOCOMO, [Search February 17, 2011], Internet <URL: http://www.nttdocomo.co.jp/binary/pdf/corporate/technology/ rd / technical_journal / bn / vol17_3 / vol17_3_015jp.pdf> 3GPP TS 23.272 Circuit Switched fallback in Evolved Packet System; Stage 2

When CS-FB is adopted, if the subscriber profile is held in the MSC / VLR 1, the above-described operation is performed, and an incoming voice call can be received even during communication by the LTE network.
By the way, a subscriber profile may be lost due to a failure or maintenance work of the MSC / VLR1, and a state in which the subscriber profile is not held in the MSC / VLR1 may occur. Even if such a situation occurs, the subscriber profile is restored during the subsequent location registration. That is, since the location registration of the mobile communication terminal is periodically performed, the subscriber profile is held in the MSC / VLR 1 at the time of location registration.

However, the subscriber profile is not held in MSC / VLR 1 until the next location registration timing after the subscriber profile is not held due to MSC / VLR 1 failure or maintenance work. Will do. If there is an incoming call while this state continues, there is a problem that the incoming call cannot be relieved.
The present invention has been made to solve the above-mentioned problems of the background art, and its purpose is to maintain a subscriber profile in the MSC / VLR due to failure, maintenance work, etc. in a communication system adopting CS-FB. An object of the present invention is to provide a circuit switching apparatus and an incoming call control method capable of normally processing an incoming call even in a state where the incoming call is not performed.

The circuit switching apparatus according to the present invention, when there is an incoming call request to the 3G network area corresponding to the base station control apparatus under its own apparatus, an address acquisition request for acquiring the address of the MME that is an exchange in the LTE network area And an incoming call control unit that performs incoming call processing on the LTE network area using the acquired address when the address of the MME is acquired in response to the address acquisition request. The address acquisition request transmission unit at least after the disappearance of the subscriber profile held by the own device and before the next location registration request after the disappearance by the mobile communication terminal subject to the incoming call request. The address acquisition request is transmitted . According to this configuration, an incoming call can be processed normally even in a state where the subscriber profile is not held in the MSC / VLR due to failure or maintenance work.

  The incoming call control unit may also perform incoming processing for the 3G network area when performing incoming processing for the LTE network area. In this way, the incoming call process can be continued regardless of which network is present.

In the incoming call control method according to the present invention, when there is an incoming call request to the 3G network area, the first step of determining whether or not the address of the MME, which is an exchange in the LTE network area, is used to perform incoming call processing ( For example, corresponding to step S2 in FIG. 8 and the second step of making an inquiry to the HLR when the address of the MME is not held as a result of the determination in the first step (for example, in FIG. 8). And a third step (for example, corresponding to steps S5 and S7 in FIG. 8) for performing an incoming call process on the LTE network area using the address of the MME obtained in the second step. look including the door, the second step is at least, after the disappearance of the subscriber profile held in the own device, the move target of the incoming request Characterized in that it is performed during the previous next position registration after the loss due to the communication terminal requests. According to this method, an incoming call can be processed normally even in a state where the subscriber profile is not held in the MSC / VLR due to failure or maintenance work.

  In the third step, when the incoming process for the LTE network area is performed, the incoming process for the 3G network area may be performed in parallel (for example, corresponding to step S7 ′ in FIG. 8). . In this way, the incoming call process can be continued regardless of which network is present.

  According to the present invention, when there is an incoming call in a state where the profile held in the MSC / VLR is lost, the HLR is inquired for the in-service MME information, and the call is performed based on the acquired information. Incoming calls can be rescued.

It is a block diagram which shows the structure of the communication system containing the circuit switching apparatus by embodiment of this invention, and the case where a 3G network is called. 1 is a block diagram showing a configuration of a communication system including a circuit switching device according to an embodiment of the present invention and a case where a call is made to an LTE network. FIG. It is a block diagram which shows the function structural example of the circuit switching apparatus by embodiment of this invention. It is a sequence diagram which shows the operation | movement in the case of performing a call to 3G network in the communication system of FIG. FIG. 3 is a sequence diagram showing an operation when a call is made to the LTE network in the communication system of FIG. 2. It is a block diagram which shows the structure of the communication system containing the circuit switching apparatus by other embodiment of this invention. It is a sequence diagram which shows operation | movement of the communication system of FIG. It is a flowchart which shows the outline | summary of a process of the communication system of FIG. 1 and FIG. It is a flowchart which shows the outline | summary of a process of the communication system of FIG. It is a figure explaining the outline | summary of the incoming call function in CS-FB. It is a sequence diagram which shows the outline | summary of CS-FB process.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the drawings referred to in the following description, the same parts as those in the other drawings are denoted by the same reference numerals.
(Embodiment)
In the circuit switching apparatus according to the embodiment of the present invention, when a call is received when CS-FB is introduced, it is confirmed whether the subscriber profile is held in the MSC / VLR. If the subscriber profile is retained as a result of this confirmation, calling (paging) is performed according to the contents of the subscriber profile.
However, when it is determined that the subscriber profile is not held in the MSC / VLR when there is an incoming call, the subscriber profile is restored by the MSC / VLR. This restoration process is a process of inquiring of the subscriber profile to the HLR and holding the acquired subscriber profile in the MSC / VLR.

(Communications system)
The operation of the communication system using the MSC / VLR which is the circuit switching device will be described with reference to FIGS. In FIG. 1, when there is an incoming call via another MSC (not shown) (S101), when it is determined that the subscriber profile is not held, the restore process is started, and the MSC / VLR1 to the HLR6. The subscriber profile is queried (S101a). Specifically, an inquiry about the MME address corresponding to the subscriber number of the mobile communication terminal to be received is made. If it is confirmed from the response to this inquiry (S101b) that there is no MME address (not stored) in the HLR 6, a call is made from the MSC / VLR1 to the 3G network area (S107). That is, a call is made to the mobile communication terminal 5 located in the 3G network area via the RNC 2. This call itself is an existing process. When a response is transmitted from the mobile communication terminal 5 to the call (S108), the MSC / VLR 1 receives the response and authenticates the mobile communication terminal 5. Thereafter, the mobile communication terminal 5 can perform voice communication by existing processing.

  In FIG. 2, when an incoming call is received via another MSC (not shown) (S101), if it is determined that the subscriber profile is not held, the restore process is started, and the MSC / VLR1 to the HLR6 In the same manner as in FIG. 1, the subscriber profile is queried (S101a). If it is confirmed by the response to this inquiry (S101b) that the HLR 6 has an MME address (stored), a call request (Paging Req) to the MME 3 is transmitted using the acquired MME address (S102). ). As a result, a call is made to the mobile communication terminal 5 located in the LTE network area via the eNodeB 4 (S103). In response to this call, when a response is transmitted from the mobile communication terminal 5, the MSC / VLR 1 receives the response via the RNC 3 (S106). Thereafter, the mobile communication terminal 5 can perform voice communication.

(MSC / VLR)
Here, a functional configuration example of the MSC / VLR 1 will be described with reference to FIG. In order to realize the processing described with reference to FIG. 1, the MSC / VLR 1 stores, as shown in FIG. 3, the storage unit 11 that stores various types of information and the HLR to acquire the address of the MME. Communication processing between the address acquisition request transmitting unit 12 that transmits a request for acquiring a subscriber profile, the incoming call control unit 13 that performs incoming processing for the LTE network area using the address acquired from the HLR, and communication processing with other devices. And a communication control unit 14 for controlling. This MSC / VLR 1 has an MSC function for circuit switching and a VLR function in which a part of information held in the HLR is temporarily held.

  In the storage area of the storage unit 11, there is a subscriber profile holding unit 11 a for holding a subscriber profile which is profile information about the subscriber of the mobile communication terminal. If the MME address is held in the subscriber profile holding unit 11a, it can be determined that the mobile communication terminal is located in the LTE network area. On the other hand, if the MME address is not held in the subscriber profile holding unit 11a, it can be determined that the mobile communication terminal is not located in the LTE network area.

(Operation of communication system)
Here, the operation of the communication system according to the present embodiment will be described with reference to FIGS. 4 and 5.
FIG. 4 is a sequence diagram showing the operation of the communication system according to the present embodiment in the case of FIG. In FIG. 4, when an incoming call is received via another MSC (not shown) (S101), the MSC / VLR1 inquires of the subscriber profile to the HLR 6 (S101a). Specifically, the MME address is inquired. If it is confirmed from the response (S101b) to the inquiry that the HLR 6 does not have an MME address, the MSC / VLR 1 calls the mobile communication terminal 5 located in the 3G network area via the RNC 2 (S107a). , S107b). In response to this call, when a response is transmitted from the mobile communication terminal 5 to the MSC / VLR 1 via the RNC 2 (S108a, S108b), the MSC / VLR 1 authenticates the mobile communication terminal 5, and thereafter, the existing processing is performed. Through the above processing, the mobile communication terminal 5 can perform voice communication.

  FIG. 5 is a sequence diagram showing the operation of the communication system according to the present embodiment in the case of FIG. In FIG. 5, when an incoming call is received via another MSC (not shown) (S101), the MSC / VLR 1 inquires of the subscriber profile to the HLR 6 (S101a). Specifically, the MME address is inquired. If it is confirmed by the response to this inquiry (S101b) that the HLR 6 has an MME address, the MSC / VLR 1 transmits a paging request (Paging Req) to the MME 3 using the MME address (S102).

  Thereafter, the MME 3 calls the mobile communication terminal 5 located in the LTE network area via the eNodeB 4 (S103a, S103b). In response to this call, when the mobile communication terminal 5 returns a response to the MME 3, a radio switching instruction is transmitted from the MME 3 to the eNodeB 4, and radio switching from LTE to 3G is performed (not shown). Thereafter, when a response is transmitted from the mobile communication terminal 5, the MSC / VLR 1 is received via the RNC 3 (S106a, S106b). Thereafter, existing processing is performed, and the mobile communication terminal 5 can perform voice communication.

As described above, when there is an incoming call in a state where the profile held in the MSC / VLR is lost, the HLR is inquired of the in-service MME information (MME address), and the call is performed based on the acquired information. Thus, the incoming call can be rescued.
(Other embodiments)
By the way, when the incoming process for the LTE network area described with reference to FIGS. 2 and 5 is performed, the incoming process for the 3G network area may be performed in parallel. The operation in that case will be described with reference to FIG.

  In FIG. 6, when there is an incoming call via another MSC (not shown) (S101), if it is determined that the subscriber profile is not held, the restore process is started, and the MSC / VLR1 to the HLR6. The subscriber profile is queried (S101a). Specifically, an inquiry about the MME address corresponding to the subscriber number of the mobile communication terminal to be received is made.

  If it is confirmed from the response (S101b) to this inquiry that the HLR 6 has (stored) the MME address, the MSC / VLR 1 transmits a paging request (Paging Req) to the MME 3 using the acquired MME address. (S102). As a result, a call is made to the mobile communication terminal 5 located in the LTE network area via the eNodeB 4 (S103). In parallel with the transmission of the call request to the MME 3, the MSC / VLR 1 calls the mobile communication terminal 5 located in the 3G network area via the RNC 2 (S107).

  In this way, when performing incoming processing for the LTE network area, if the incoming processing for the 3G network area is also performed in parallel, the MSC / VLR 1 can receive a response from the mobile communication terminal 5 (S106). In addition, a response is returned from the mobile communication terminal 5 to the MME 3 (S104), and after the wireless switching from LTE to 3G is performed, the MSC / VLR 1 can receive the response from the mobile communication terminal 5 (S108). That is, regardless of whether the mobile communication terminal 5 is located in the 3G network or the LTE network, the mobile communication terminal 5 can receive a call from the MSC / VLR 1 (S103, S107) and perform voice communication. it can.

In order to realize the above processing, the incoming call control unit 13 in the MSC / VLR 1 described with reference to FIG. 3 should perform incoming processing in parallel to the LTE network area and the 3G network area. That's fine.
Furthermore, it demonstrates with reference to a sequence diagram. FIG. 7 is a sequence diagram showing an operation in the case of FIG. 6 of the communication system according to the present embodiment.

In FIG. 7, when an incoming call is received via another MSC (not shown) (S101), the MSC / VLR 1 inquires of the subscriber profile to the HLR 6 (S101a). Specifically, the MME address is inquired.
If it is confirmed from the response (S101b) to this inquiry that the HLR 6 has an MME address (stored), the MSC / VLR 1 transmits a call request (Paging Req) to the MME 3 using the acquired MME address. (S102). As a result, the MSC / VLR 1 calls the mobile communication terminal 5 located in the LTE network area via the eNodeB 4 (S103a, S103b). In parallel with the transmission of the call request to the MME 3, the MSC / VLR 1 calls the mobile communication terminal 5 located in the 3G network area via the RNC 2 (S107a, S107b).

In response to these calls, the mobile communication terminal 5 performs the process A when it is in the LTE network area or the process B when it is in the 3G network area.
In the process A in the case of being in the LTE network area, the mobile communication terminal 5 returns a response to the MME 3 via the eNodeB 4 in response to the call from the MME 3 (S104a, S104b). Thereafter, a radio switching instruction is transmitted from the MME 3 to the eNodeB 4 (S105).

After the radio switching from LTE to 3G is performed, a response from the mobile communication terminal 5 is transmitted to the MSC / VLR 1 via the RNC 2 (S106a, S106b). Thereafter, existing processing is performed, and a voice call is performed between a communication terminal (not shown) and the MT 5.
On the other hand, in the process B in the case of being in the 3G network area, the mobile communication terminal 5 returns a response to the MSC / VLR1 via the RNC2 in response to the call from the MSC / VLR1 (S108a, S108b). ). Thereafter, existing processing is performed, and a voice call is performed between a communication terminal (not shown) and the MT 5.

(Modification)
In the communication system described above, the case where the MSC function and the VLR function are realized by the same device has been described, but these functions may be realized by different devices.
In the communication system described above, the case where the MSC / VLR and the RNC correspond one-to-one has been described. However, a plurality of RNCs may correspond to the MSC / VLR.
In the communication system described above, the case where the MME and the eNodeB correspond one-to-one has been described. However, a plurality of eNodeBs may correspond to the MME.

(Incoming call control method)
In the MSC / VLR of the communication system described with reference to FIGS. 1 to 5, the following incoming call control method is adopted. That is, as shown in FIG. 8, it is determined whether there is an incoming call (step S1). If there is an incoming call, it is determined whether the subscriber profile is held (step S2). If the subscriber profile is held, CS-FB processing is performed (step S3). On the other hand, if the subscriber profile is not held, an inquiry is made to the HLR (step S4), and if there is no MME address (if it is not acquired), a call is made to the 3G network (step S5 → S6). . On the other hand, if the MME address is acquired by inquiry to the HLR, a call is made to the LTE network (steps S5 → S7).

As described above, the MME address is acquired from the HLR before the call is made, and the incoming call processing is performed via the MME, so that even when the mobile communication terminal is located in the LTE network area, the incoming call processing is performed. Can continue.
In the MSC / VLR of the communication system described with reference to FIG. 6 and FIG. 7, the following incoming call control method is adopted. That is, as shown in FIG. 9, it is determined whether there is an incoming call (step S1). If there is an incoming call, it is determined whether the subscriber profile is held (step S2). If the subscriber profile is held, CS-FB processing is performed (step S3). On the other hand, if the subscriber profile is not held, an inquiry is made to the HLR (step S4), and if there is no MME address (if it is not acquired), a call is made to the 3G network (step S5 → S6). . On the other hand, if the MME address is acquired by inquiry to the HLR, a call is made to the LTE network and the 3G network (step S5 → S7 ′).
As described above, by making a call to both the LTE network and the 3G network, it is possible to continue the processing by the incoming call regardless of which area the mobile communication terminal is in.

(Summary)
If the subscriber profile held in the MSC / VLR is lost due to a failure or maintenance work, an inquiry to the HLR is made before making a call in order to solve the problem that voice incoming calls cannot be relieved for the mobile station in LTE communication. And by making a call according to the acquired MME address, the processing by the incoming call can be continued.

  It should be noted that the scope of the present invention is not limited to the illustrated and described exemplary embodiments, but includes all embodiments that provide the same effects as those intended by the present invention. Further, the scope of the invention is not limited to the combinations of features of the invention defined by the claims, but may be defined by any desired combination of particular features among all the disclosed features. .

  The present invention can be used in a circuit switching apparatus that performs incoming processing on a mobile communication terminal.

1 MSC / VLR
2 RNC
3 MME
4 eNodeB
5 Mobile communication terminal 6 HLR
11 Storage Unit 11a Subscriber Profile Holding Unit 12 Address Acquisition Request Transmitting Unit 13 Incoming Control Unit 14 Communication Control Unit

Claims (4)

An address acquisition request transmitter for transmitting an address acquisition request for acquiring the address of the MME that is an exchange in the LTE network area when there is an incoming call request to the 3G network area corresponding to the base station controller under its own device If, when acquiring the address of the MME by the response to the address acquisition request, using the obtained address, seen including a receiving controller, the performing call processing for the LTE network area,
The address acquisition request transmission unit at least after the loss of the subscriber profile held by the own device and before the next location registration request after the loss by the mobile communication terminal that is the target of the incoming call request, A circuit switching device characterized by transmitting an address acquisition request .   The circuit switching device according to claim 1, wherein the incoming call control unit also performs incoming call processing on the 3G network area in parallel with incoming call processing on the LTE network area. A first step of determining whether or not the address of the MME, which is an exchange of the LTE network area, used to perform the incoming call processing when there is an incoming call request to the 3G network area, and the determination by the first step As a result, when the address of the MME is not held, a second step of making an inquiry to the HLR and an incoming call processing for the LTE network area using the address of the MME acquired by the second step are performed. and a third step seen including,
The second step is executed at least after the disappearance of the subscriber profile held by the own device and before the next location registration request after the disappearance by the mobile communication terminal subject to the incoming call request. An incoming call control method.   4. The incoming call control method according to claim 3, wherein in the third step, the incoming call processing for the 3G network area is also performed in parallel with the incoming call processing for the LTE network area.

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