JP5956850B2 - Mobile communication system, mobility management apparatus, and mobile communication method - Google Patents

Description

  The present invention relates to a mobile communication system, a mobile management device, and a mobile communication method capable of connecting a specific call processed with priority over a general call.

  Long Term Evolution (LTE) defines Voice over LTE (VoLTE), which enables connection of voice communication calls via an Internet protocol (IP) -based network (IP-Connectivity Access Network (IP-CAN)) Has been. In VoLTE, a procedure for handling a highly urgent emergency call such as transmission to the police or fire department with the highest priority is defined (for example, see Non-Patent Document 1).

  FIG. 1 shows a communication sequence when a mobile station (UE) issues an emergency call in the Preservation state. As shown in FIG. 1, when an emergency call is transmitted by the UE in the Preservation state, a UE requested PDN connectivity procedure is executed. The Preservation state is a state in which a communication bearer for general calls that is not an emergency call (VoLTE bearer) has been set and the radio link has been released. When an emergency call is transmitted in such a Preservation state, an emergency call communication bearer (specifically, PDN Connection) different from the general call communication bearer is set.

  In the case of the Preservation state, it is necessary to temporarily restore the radio link used for the communication bearer for general calls before setting up the communication bearer for emergency calls. Therefore, a Service Request procedure and an Initial Context Setup Request procedure are executed.

  In the Initial Context Setup Request procedure, the radio base station (eNB) transmits an Initial UE Message (Service Request) to the Mobility Management Entity (MME) based on the RRC (Service Request) transmitted from the UE (S10, S20). ). The RRC and Initial UE Message include information (RRC Establishment cause: emergency) indicating an emergency call.

  The MME refers to the Preservation state of the UE and transmits an Initial Context Setup Request to the eNB (S30), and the eNB responds to the MME with Initial Context Setup Complete (S40). By this processing, the emergency bearer communication bearer is set up between the eNB and the MME. Here, since the communication bearer for general calls is held as the Preservation state, the MME, as the E-RAB Level QoS_ARP (Allocation and Retention Policy) included in the Initial Context Setup Request, The priority of the communication bearer for general calls is set.

  Further, the MME transmits, to the S-GW, a Modify Bearer Request that requests a setting change of the communication bearer between the eNB and the serving gateway device (S-GW) according to the Service Request procedure (S50). The Modify Bearer Request includes an identifier of a communication bearer set between the eNB and the S-GW.

  In addition, when a priority call sent by a priority user (UE) determined by a contract is preferentially processed over a general call sent by a general user (UE), the procedure is almost the same as that of an emergency call. It is prescribed. FIG. 2 shows a communication sequence in the case where the priority user UE makes a voice communication call (priority call) in the Preservation state.

  As shown in FIG. 2, when a priority call is transmitted by the UE in the Preservation state, a Service Request procedure is executed, and reconfiguration of communication bearers is started based on the Preservation state (S110, S120). The RRC and Initial UE Message include information indicating that the call is a priority call (RRC Establishment cause: highPriorityAccess). The MME refers to the Preservation state of the UE and transmits an Initial Context Setup Request to the eNB (S130), and the eNB responds to the MME with Initial Context Setup Complete (S140). Further, the MME transmits, to the S-GW, a Modify Bearer Request that requests a setting change of the communication bearer between the eNB and the serving gateway device (S-GW) according to the Service Request procedure (S150). The Modify Bearer Request includes an identifier of a communication bearer set between the eNB and the S-GW.

3GPP TS 23.401 V11.0.0 Subclause 5.10.2 UE requested PDN connectivity, 3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; General Packet Radio Service (GPRS) enhancements for Evolved Universal Terrestrial Radio Access Network (E-UTRAN) access ( Release 11), December 2011

  However, the above-described conventional call processing procedures such as emergency calls and priority calls have the following problems. That is, the MME cannot identify whether the Initial Context Setup Complete received from the eNB has been transmitted with the origination of the specific call, and the specific call in the Modify Bearer Request transmitted to the S-GW. It cannot contain information indicating that

  For this reason, a specific call cannot be preferentially processed in the S-GW, and there is a possibility that the connection of the specific call fails (see the lower part of FIGS. 1 and 2).

  Therefore, the present invention has been made in view of such a situation, and an object of the present invention is to provide a mobile communication system, a mobile management device, and a mobile communication method that can connect an emergency call more quickly and reliably even in the Preservation state. To do.

  A first feature of the present invention includes a mobility management device that manages mobility of a mobile station and a serving gateway device, and connects a specific call that is processed with priority over other general calls originated by the mobile station The mobile management device includes a service request acquisition unit that acquires a service request generated when a specific call is transmitted from a radio base station, and information indicating a specific call When receiving a bearer setup response to the bearer setup request from the radio base station, based on the service request acquired by the service request acquisition unit, a bearer change request including specific call information indicating a specific call is provided in the serving A bearer change request transmitter for transmitting to the gateway device, wherein the serving gateway device receives the bearer received from the mobility management device. The contained to a further request based on specific call information, and summarized in that comprises a bearer modification processing unit for processing in preference to the bearer modification request general call the bearer modification request.

A second feature of the present invention is a mobility management apparatus included in a mobile communication system capable of connecting a specific call that is processed with priority over other general calls transmitted by a mobile station. When a service request acquisition unit that acquires a service request generated along with a call origination and a bearer setting response to a bearer setting request that includes information indicating a specific call are received from the radio base station, the service request A gist is provided with a bearer change request transmission unit that transmits a bearer change request including specific call information indicating a specific call to the serving gateway device based on the service request acquired by the acquisition unit.

  According to a third aspect of the present invention, there is provided a mobile communication method for connecting a specific call that is processed with priority over other general calls transmitted by a mobile station. Obtaining a service request generated along with a call, and when the mobility management apparatus receives a bearer setup response to the bearer setup request including information indicating that the call is a specific call, from the radio base station. Transmitting a bearer change request including specific call information indicating a specific call to the serving gateway device based on the service request; and the bearer change request received from the mobility management device by the serving gateway device. And processing the bearer change request in preference to the bearer change request for a general call based on the specific call information included in The the gist.

  According to the features of the present invention, it is possible to provide a mobile communication system, a mobile management device, and a mobile communication method that can connect an emergency call more quickly and reliably even in the Preservation state.

It is a figure which shows the conventional communication sequence in case a mobile station transmits an emergency call. It is a figure which shows the conventional communication sequence in case a priority user's mobile station transmits a voice communication call (priority call). 1 is an overall schematic configuration diagram of a mobile communication system 10 according to an embodiment of the present invention. It is a functional block block diagram of MME40 which concerns on embodiment of this invention. It is a functional block block diagram of S-GW50 which concerns on embodiment of this invention. It is a figure which shows the communication sequence regarding the connection of the emergency call using Emergency Indicator which concerns on embodiment of this invention. It is a figure which shows the communication sequence regarding the connection of the emergency call using QoS_ARP which concerns on embodiment of this invention. It is a figure which shows the communication sequence regarding the connection of the priority call using High Priority Indicator which concerns on embodiment of this invention. It is a figure which shows the communication sequence regarding the connection of the priority call using QoS_ARP which concerns on embodiment of this invention. It is a figure which shows the communication sequence regarding the connection of the priority call based on the example of a change of this invention. It is a figure which shows notionally an example of the context information which S-GW50 which concerns on the example of a change of this invention hold | maintains.

  Next, an embodiment of the present invention will be described. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of dimensions and the like are different from actual ones.

  Accordingly, specific dimensions and the like should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

(1) Overall Schematic Configuration of Mobile Communication System FIG. 3 is an overall schematic configuration diagram of the mobile communication system 10 according to the present embodiment. As shown in FIG. 3, a mobile station 20 (hereinafter referred to as UE20), a radio base station 30 (hereinafter referred to as eNB30), a mobility management device (hereinafter referred to as MME40), a serving gateway device 50 (hereinafter referred to as S-GW50), a PDN gateway device 60 (hereinafter referred to as P-GW60) and a policy / billing control device (hereinafter referred to as PCRF70). The mobile communication system 10 may include a home subscriber server (HSS), and the P-GW 60 includes an IP-based external network (packet data network) such as an IP multimedia core network subsystem (IMS). Connected.

  The MME 40 is an exchange that accommodates the eNB 30 and manages mobility of the UE 20 by providing mobility control, a bearer control function, and the like. The S-GW 50 is a visited packet switch that accommodates a 3GPP (LTE) access system. The P-GW 60 is a connection point with the IMS platform, and is a packet switch that performs IP address assignment, packet transfer to the S-GW 50, and the like. Further, the P-GW 60 executes QoS control, bearer setting control, and the like in cooperation with the PCRF 70. The PCRF 70 is a logical node that executes control for QoS and charging for user data transfer.

  The mobile communication system 10 can connect a specific call that is processed with priority over other voice communication calls (general calls) originated by the UE 20. Specifically, the specific call includes an emergency call such as a call to the police or a fire department, and a priority call sent by a priority user UE defined in a contract or the like.

(2) Functional Block Configuration of Mobile Communication System Next, a functional block configuration of the mobile communication system 10 will be described. FIG. 4 is a functional block configuration diagram of the MME 40. FIG. 5 is a functional block configuration diagram of the S-GW50.

(2.1) MME40
As illustrated in FIG. 4, the MME 40 includes a state holding unit 41, a service request acquisition unit 43, and a bearer change request transmission unit 45.

  The state holding unit 41 holds the state of the communication bearer for general calls set between the UE 20 and the MME 40. Specifically, the state holding unit 41 holds the Preservation state in which a communication bearer for general calls that is not an emergency call (VoLTE bearer) has been set and the radio link is released.

  The service request acquisition unit 43 acquires a service request generated with an emergency call from the eNB 30. Specifically, the service request acquisition unit 43 receives an Initial UE Message (Service Request) transmitted from the eNB 30. The Initial UE Message (Service Request) includes information (RRC Establishment cause: emergency) indicating an emergency call.

  The bearer change request transmission unit 45 receives a bearer setting response to the bearer setting request including information indicating that the call is a specific call from the radio base station. Specifically, the bearer change request transmission unit 45 receives an Initial Context Setup Complete (bearer setup response) in response to an Initial Context Setup Request (bearer setup request) including information indicating a specific call.

  When receiving the Initial Context Setup Complete for the Initial Context Setup Request including information indicating the specific call, the bearer change request transmitting unit 45 is based on the Initial UE Message (Service Request) acquired by the service request acquiring unit 43. Then, a bearer change request including specific call information indicating a specific call is transmitted to the S-GW 50. Specifically, the bearer change request transmission unit 45 transmits a Modify Bearer Request (bearer change request) including specific call information to the S-GW 50.

  The bearer change request transmission unit 45 can transmit a Modify Bearer Request with the emergency indicator (specific call identifier) indicating the specific call as specific call information. Note that the bearer change request transmission unit 45 can transmit a Modify Bearer Request including an Emergency Indicator regardless of the state of the communication bearer for general calls held by the state holding unit 41.

  Further, the bearer change request transmission unit 45 uses, as specific call information, QoS_ARP (service quality information) indicating that the quality of service applied to the communication bearer set in accordance with the Initial Context Setup Request is higher than that of a general call. A Modify Bearer Request can be sent. Specifically, the bearer change request transmission unit 45 indicates that the priority is higher than the general call as QoS_ARP regardless of the state of the communication bearer for the general call held by the state holding unit 41. "Is set.

(2.2) S-GW50
As shown in FIG. 5, the S-GW 50 includes a state holding unit 51, a bearer change request receiving unit 53, and a bearer change processing unit 55.

  The state holding unit 51 holds the state of the communication bearer for general calls set between the eNB 30 and the S-GW 50. Specifically, the state holding unit 41 holds the Preservation state in which a communication bearer for general calls that is not an emergency call (VoLTE bearer) has been set and the radio link is released.

  The bearer change request receiving unit 53 receives the Modify Bearer Request transmitted by the MME 40.

  The bearer change processing unit 55 processes the Modify Bearer Request with priority over the Modify Bearer Request of the general call based on the specific call information included in the Modify Bearer Request received by the bearer change request receiving unit 53 from the MME 40. Specifically, based on the Emergency Indicator or QoS_ARP included in the bearer change processing unit 55, the bearer change processing unit 55 sets Modify Bearer Request including the Emergency Indicator and QoS_ARP to “emergency” (priority). The existing Modify Bearer Request is processed with priority over other Modify Bearer Requests.

(3) Operation of Mobile Communication System Next, the operation of the mobile communication system 10 will be described. Specifically, a communication sequence related to connection of an emergency call and a priority call that is a voice communication call processed with priority over other general calls will be described.

(3.1) Operation example 1 (emergency call / emergency indicator)
FIG. 6 shows a communication sequence related to emergency call connection using Emergency Indicator. In the following, portions different from the conventional communication sequence shown in FIG. 1 will be mainly described, and descriptions of portions similar to the conventional communication sequence will be omitted as appropriate.

  As illustrated in FIG. 6, the MME 40 receives an Initial UE Message (Service Request) including RRC Establishment cause: emergency from the eNB 30 (S220). Based on the RRC Establishment cause: emergency included in the Initial UE Message (Service Request) received from the eNB 30, the MME 40 recognizes that the Initial UE Message (Service Request) is generated with an emergency call.

  Moreover, when MME40 receives Initial Context Setup Complete, which is a response to Initial UE Message (Service Request), from eNB30, Initial UE Message (Service Request) corresponding to the received Initial Context Setup Complete is generated along with an emergency call. Based on the fact that it is recognized, a Modify Bearer Request including an Emergency Indicator is transmitted to the eNB 30 (S250). Note that the MME 40 can transmit a Modify Bearer Request including an Emergency Indicator regardless of the state of the communication bearer for general calls held as the Preservation state.

  The S-GW 50 that has received the Modify Bearer Request processes the Modify Bearer Request with priority over other Modify Bearer Requests based on the Emergency Indicator.

(3.2) Operation example 2 (emergency call / QoS_ARP use)
FIG. 7 shows a communication sequence related to emergency call connection using QoS_ARP. As illustrated in FIG. 7, the MME 40 receives an Initial UE Message (Service Request) including RRC Establishment cause: emergency from the eNB 30 (S320). Based on the RRC Establishment cause: emergency included in the Initial UE Message (Service Request) received from the eNB 30, the MME 40 recognizes that the Initial UE Message (Service Request) is generated with an emergency call.

  When MME40 receives Initial Context Setup Complete, which is a response to Initial UE Message (Service Request), from eNB30, Initial UE Message (Service Request) corresponding to the received Initial Context Setup Complete is generated along with an emergency call. Based on recognizing that there is QoS_ARP: Modify Bearer Request including emergency is transmitted to eNB 30 (S350).

  The S-GW 50 that has received the Modify Bearer Request processes the Modify Bearer Request with priority over other Modify Bearer Requests based on the Emergency Indicator.

(3.3) Operation example 3 (Priority call / High Priority Indicator use)
FIG. 8 shows a communication sequence related to connection of a priority call using the High Priority Indicator. As shown in FIG. 8, the processing up to step S450 is substantially the same as in the first operation example.

  When MME40 receives Initial Context Setup Complete, which is a response to Initial UE Message (Service Request), from eNB30, Initial UE Message (Service Request) corresponding to the received Initial Context Setup Complete is generated along with the priority call. Recognize that there is. Specifically, the MME 40 is based on the fact that the communication bearer for the priority call has been set as the Preservation state or that the received Initial UE Message (Service Request) includes RRC Establishment cause: highPriorityAccess. Recognize that the received Initial Context Setup Complete was generated with a priority call.

  The MME 40 transmits a Modify Bearer Request including the High Priority Indicator to the S-GW 50 based on recognizing that the received Initial Context Setup Complete is generated with a priority call (S450).

  The S-GW 50 that has received the Modify Bearer Request processes the Modify Bearer Request with priority over other Modify Bearer Requests based on the High Priority Indicator.

(3.4) Operation example 4 (priority call / QoS_ARP use)
FIG. 9 shows a communication sequence related to priority call connection using QoS_ARP. As shown in FIG. 9, the processing up to step S550 is substantially the same as in the operation example 3.

  When MME40 receives Initial Context Setup Complete, which is a response to Initial UE Message (Service Request), from eNB30, Initial UE Message (Service Request) corresponding to the received Initial Context Setup Complete is generated along with the priority call. Recognize that there is. Specifically, in the same manner as in the operation example 3, the MME 40 has already set a communication bearer for a priority call as a Preservation state, or includes RRC Establishment cause: highPriorityAccess in the received Initial UE Message (Service Request). Based on the above, it is recognized that the received Initial Context Setup Complete is generated with the priority call.

  The MME 40 transmits a Bearer QoS: Modify Bearer Request including priority to the S-GW 50 based on recognizing that the received Initial Context Setup Complete is generated with a priority call (S550).

  The S-GW 50 that has received the Modify Bearer Request processes the Modify Bearer Request with priority over other Modify Bearer Requests based on the Bearer QoS: priority included in the Modify Bearer Request.

(4) Modified Example Next, a modified example of the operation by the MME 40 and the S-GW 50 described above will be described. FIG. 10 shows a communication sequence related to the priority call connection according to this modification. As shown in FIG. 10, the processing up to step S650 is substantially the same as in the operation example 4 and the like.

  Upon receiving Initial Context Setup Complete, which is a response to the Initial UE Message (Service Request), from the eNB 30, the MME 40 acquires the EPS Bearer ID associated with the Initial Context Setup Complete. Since the EPS Bearer ID is held in the Preservation state, the MME 40 acquires the EPS Bearer ID based on the held information.

  The MME 40 (bearer change request transmission unit 45) transmits a Modify Bearer Request including the acquired EPS Bearer ID to the S-GW 50 (S650).

  The S-GW 50 that has received the Modify Bearer Request determines whether the Modify Bearer Request should be processed with priority based on the EPS Bearer ID included in the Modify Bearer Request. Specifically, based on the context information held by the S-GW 50, it is determined whether or not the Modify Bearer Request should be processed with priority.

  FIG. 11 is a diagram conceptually illustrating an example of context information held by the S-GW 50. As shown in FIG. 11, the S-GW 50 is applied to a tunnel endpoint identifier (TEID) used for setting a communication bearer, an EPS Bearer ID for identifying the communication bearer, and the communication bearer. Service quality (EPS Bearer QoS) etc. can be held for each UE, for example.

  The S-GW 50 refers to the ARP (Allocation and Retention Policy) and QCI (Quality Class Indicator) values, which are EPS Bearer QoS values, and determines whether or not the received Modify Bearer Request should be processed with priority. When the ARP value is set to “priority”, the S-GW 50 processes the Modify Bearer Request with priority over other Modify Bearer Requests.

(4) Operation / Effect According to the mobile communication system 10, even in the Preservation state, the Emergency Bearer Request transmitted from the MME 40 to the S-GW 50 includes an Emergency Indicator or High Priority Indicator, and QoS_ARP is set to “Emergency” or “Priority”. Can be set. Alternatively, based on the EPS Bearer ID included in the Modify Bearer Request, the S-GW 50 can determine whether or not the Modify Bearer Request is associated with the transmission of a priority call.

  For this reason, even in the S-GW 50, a specific call such as an emergency call or a priority call can be processed with priority, and the possibility that the connection of the specific call will fail can be greatly reduced.

  Furthermore, in the present embodiment, the state of the communication bearer for general calls held in the MME 40, specifically, a Modify Bearer Request (bearer change request) including an Emergency Indicator or a High Priority Indicator, regardless of the Preservation state, or A Modify Bearer Request with QoS_ARP set to “Emergency” or “Priority” can be transmitted. For this reason, even if it is a Preservation state, possibility that the connection of a specific call will fail can be reduced.

(5) Other Embodiments As described above, the content of the present invention has been disclosed through one embodiment of the present invention. However, it is understood that the description and drawings constituting a part of this disclosure limit the present invention. should not do. From this disclosure, various alternative embodiments will be apparent to those skilled in the art.

  For example, in the above-described embodiment, a Bearer change request including Emergency Indicator or High Priority Indicator or Modify Bearer Request with QoS_ARP set to “Emergency” or “Priority” is transmitted regardless of the Preservation state. Such processing is not necessarily essential. That is, even when not in the Preservation state, the communication sequences according to the above-described operation examples 1 to 4 and the modification example may be executed.

  In the above-described embodiment, the voice communication call according to VoLTE has been described as an example. However, the application range of the present invention is not limited to the voice communication call. For example, the concept of an emergency call or a priority call can be considered in data communication. For example, in the case of a priority user based on contract information, the above-described voice communication call and data communication call are handled with priority over general user calls (general calls). The emergency call is generally only a voice communication call, but an emergency data communication service concept is also conceivable. For example, it is conceivable to acquire location information of a mobile station that has made an emergency call (voice communication) or to acquire data stored in the mobile station.

  As described above, the present invention naturally includes various embodiments that are not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

  The present invention may be expressed as follows. The first feature of the present invention includes an MME 40 (mobile management device) that manages the mobility of UE 20 (mobile station), and an S-GW 50 (serving gateway device), from other general calls originated by the mobile station Is a mobile communication system 10 (mobile communication system) capable of connecting a specific call processed with priority, and the mobility management device is configured to transmit an Initial UE Message ( Service Request) (Service Request Acquisition Unit) 43 (Service Request Acquisition Unit) and Initial Context Setup Complete (bearer setup request) for Initial Context Setup Request (bearer setup request) including information indicating a specific call Specific call information (for example, Emergency Indica) indicating that the call is a specific call based on the service request acquired by the service request acquisition unit when the response is received from the radio base station tor) including a bearer change request transmitting unit 45 (bearer change request transmitting unit) that transmits a bearer change request to the serving gateway device, the serving gateway device responding to the bearer change request received from the mobility management device. The gist is provided with a bearer change processing unit 55 (bearer change processing unit) that processes the bearer change request in preference to the bearer change request for a general call based on the specific call information included.

  In the first aspect of the present invention, the bearer change request transmission unit transmits the bearer change request with the emergency call or high priority indicator (specific call identifier) indicating the specific call as the specific call information. Also good.

  In the first feature of the present invention, the bearer change request transmission unit includes QoS_ARP (service quality) indicating that the service quality applied to the communication bearer set in accordance with the bearer setting request is higher than that of the general call. The bearer change request with the information) as the specific call information may be transmitted.

  In the first aspect of the present invention, the system includes a state holding unit 41 (state holding unit) that holds a state of the communication bearer for general calls set between the mobile station and the mobility management device. The change request transmission unit may transmit the bearer change request including the specific call information regardless of the state of the general call communication bearer held by the state holding unit.

A second feature of the present invention is a mobility management apparatus included in a mobile communication system capable of connecting a specific call that is processed with priority over other general calls transmitted by a mobile station. When a service request acquisition unit that acquires a service request generated along with a call origination and a bearer setting response to a bearer setting request that includes information indicating a specific call are received from the radio base station, the service request A gist is provided with a bearer change request transmission unit that transmits a bearer change request including specific call information indicating a specific call to the serving gateway device based on the service request acquired by the acquisition unit.

  According to a third aspect of the present invention, there is provided a mobile communication method for connecting a specific call that is processed with priority over other general calls transmitted by a mobile station. Obtaining a service request generated along with a call, and when the mobility management apparatus receives a bearer setup response to the bearer setup request including information indicating that the call is a specific call, from the radio base station. Transmitting a bearer change request including specific call information indicating a specific call to the serving gateway device based on the service request; and the bearer change request received from the mobility management device by the serving gateway device. And processing the bearer change request in preference to the bearer change request for a general call based on the specific call information included in The the gist.

10 ... Mobile communication system
20 ... UE
30 ... eNB
40 ... MME
41 ... State holding part
43 ... Service Request Acquisition Department
45 ... Bearer setting request transmitter
50 ... S-GW
51 ... State holding part
53 ... Bearer change request receiver
55 ... Bearer change processing part
60 ... P-GW
70… PCRF

Claims (5)

A mobile communication system that includes a mobility management device that manages mobility of a mobile station and a serving gateway device, and is capable of connecting a specific call that is processed with priority over other general calls originated by the mobile station,
The mobility management device
A service request acquisition unit for acquiring a service request generated when a specific call is transmitted from a radio base station;
When a bearer setup response to a bearer setup request including information indicating that the call is a specific call is received from the radio base station, a specification indicating that the call is a specific call based on the service request acquired by the service request acquisition unit A bearer change request transmission unit that transmits a bearer change request including call information to the serving gateway device ;
A state holding unit that holds the preservation state in which the communication bearer for the general call set between the mobile station and the mobility management device has been set and the radio link is released. With
The serving gateway device, based on the specific call information included in the bearer change request received from the mobility management device, processes the bearer change request with priority over the general call bearer change request. equipped with a,
The bearer change request transmission unit, regardless of the Preservation state of the communication bearer for the general call held by the state holding unit, the mobile communication system that sends the bearer modification request including the specific call information.   The mobile communication system according to claim 1, wherein the bearer change request transmission unit transmits the bearer change request using a specific call identifier indicating a specific call as the specific call information.   The bearer change request transmission unit uses the quality of service information indicating that the quality of service applied to the communication bearer set with the bearer setting request is higher than that of the general call as the specific call information. The mobile communication system according to claim 1, wherein the request is transmitted. A mobility management device included in a mobile communication system capable of connecting a specific call processed with priority over other general calls originated by a mobile station,
A service request acquisition unit for acquiring a service request generated when a specific call is transmitted from a radio base station;
When a bearer setup response to a bearer setup request including information indicating that the call is a specific call is received from the radio base station, a specification indicating that the call is a specific call based on the service request acquired by the service request acquisition unit a bearer modification request transmitting unit that transmits the bearer modification request including the call information to the service over Bing gateway device,
A state holding unit that holds the preservation state in which the communication bearer for the general call set between the mobile station and the mobility management device has been set and the radio link is released. equipped with a,
The bearer change request transmission unit, regardless of the Preservation state of the communication bearer for the general call held by the state holding unit, the specific call information mobile management device that sends the bearer modification request including the. A mobile communication method for connecting a specific call processed in preference to other general calls originated by a mobile station,
The mobility management device acquiring a service request generated with a specific call from the radio base station;
The mobility management device holds the Preservation state in which the communication bearer for the general call set between the mobile station and the mobility management device has been set and the radio link is released; ,
When the mobility management device receives a bearer setup response to the bearer setup request including information indicating that the call is a specific call from the radio base station, the mobile management device indicates the specific call based on the acquired service request sending a bearer modification request including the call information to the service over Bing gateway device,
The serving gateway device processing the bearer change request in preference to the bearer change request for a general call based on the specific call information included in the bearer change request received from the mobility management device. See
In the step of transmitting the bearer change request, the mobile communication method of transmitting the bearer change request including the specific call information regardless of a preservation state of the general-purpose communication bearer that is held .

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