NETWORK DEVICE, USER TERMINAL, COMMUNICATION CONTROL METHOD, AND PROGRAM FOR TRANSMITTING AND RECEIVING DATA USING MULTIPLE BEARERS

Abstract

To more efficiently accommodate user terminals in a mobile communication system in which one user terminal is capable of establishing a plurality of bearers for data communications.SOLUTION: A network device, which is disposed in a core network, for determining a base station respectively accommodating a plurality of bearers established by a user terminal (UE) for data communications and a gateway (GW) receives an establishment request of a bearer from a first UE via the base station, determines a predetermined GW for accommodating the bearer from among a plurality of GWs in the core network in response to the establishment request received from the first UE, instructs the determined GW to secure predetermined resources for establishing the bearer, and in response to an establishment request of a bearer received from a second UE which is different from the first UE, instructs the predetermined GW to establish the predetermined bearer between the second UE and the predetermined GW using the predetermined resources.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a network device, a user terminal, a communication control method, and a program for transmitting and receiving data using a plurality of bearers. [Background technology]

[0002] In a mobile communication system, a user terminal (UE) accesses a core network (mobile core) via a radio access network (RAN). The mobile core has a user plane (U-Plane) function for transmitting user data and a control plane (C-Plane) function for controlling mobility management, session management, and the like. The session control function of the mobile core manages user session information and establishes and releases bearers, which are communication paths. In the mobile core, the transmission of user data is performed by a gateway (GW). Bearer settings, such as the selection of a GW to which a user terminal connects for data communication, are performed by the session control function. In a fifth-generation (5G) mobile communication system, the GW is called a "User Plane Function (UPF)" and the session control function is called a "Session Management Function (SMF)". Non-Patent Documents 1 and 2 specify such a mobile communication system.

[0003] In future mobile communication systems, the volume of user data transferred is expected to increase. Non-Patent Document 3 describes a technology for performing communication using multiple bearers. Such a technology can be utilized to realize large-volume communication. In such an architecture, it is expected that a UE will establish multiple bearers with one or more base stations to perform communication. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP TS 23.501 V17.0.0, "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; System architecture for the 5G System (5GS); Stage 2 (Release 17)" [Non-Patent Document 2] 3GPP TS 23.502 V17.0.0, "3rd Generation Partnership Project; Technical Specification Group Services and System Aspects; Procedures for the 5G System (5GS); Stage 2 (Release 17)" [Non-Patent Document 3] IEEE / ACM Transactions on Networking (Volume: 14, Issue: 6, Dec. 2006), "Multi-Path TCP: A Joint Congestion Control and Routing Scheme to Exploit Path Diversity in the Internet" Summary of the Invention [Problem to be solved by the invention]

[0005] In the mobile communication system described above, for example, when bearers are added sequentially in response to detection of a bandwidth shortage, it takes a certain amount of time to establish the bearers, and therefore it may take some time before data communication such as application communication can start. For this reason, the mobile communication system can handle an increase in the volume of user data with low latency by pre-establishing multiple bearers that the UE can use, setting bearers that are not used for communication to an inactive state (standby state), and using bearers that have been transitioned from the standby state to the active state according to the volume of user data to be transferred.

[0006] Here, if the amount of user data required by the UE increases and the number of communication sessions to be established increases, the number of bearers set to idle state increases, which may reduce the number of UEs that can be accommodated by the gateway forwarding the user data.

[0007] The present invention has been made in consideration of the above-mentioned problems, and aims to provide a technique that enables more efficient accommodation of user terminals in a mobile communication system in which one user terminal can establish multiple bearers for data communication. [Means for solving the problem]

[0008] According to one aspect of the present invention, there is provided a network device disposed in a core network, which determines a base station and a gateway (GW) accommodating each of a plurality of bearers established by a user equipment (UE) for data communication, comprising: A receiving means for receiving a bearer establishment request; A control means for controlling bearers accommodated in a plurality of GWs in the core network; Equipped with The control means In response to receiving a bearer establishment request from a first UE, instruct the first GW to establish a first bearer between a first GW of the plurality of GWs and a first base station of a plurality of base stations in the core network; After establishing the first bearer, between the first GW and the first base station, Not associated with UE determining whether to establish an additional bearer; If it is determined that an additional bearer should be established, No. 2 Instruct the first GW to establish a bearer for After instructing the first GW to establish the second bearer, The receiving means receives the bearer from the first UE. addition In response to receiving the request, 2 and instructing the first base station to establish a predetermined bearer between the first UE and the first base station in association with the bearer of the first UE. A network device is provided. Effect of the Invention

[0009] According to the present invention, it is possible to provide a technique that enables more efficient accommodation of user terminals in a mobile communication system in which one user terminal can establish multiple bearers for data communication. [Brief description of the drawings]

[0010] [Figure 1] A diagram showing an example of the configuration of a mobile communication system. [Diagram 2] A block diagram showing an example of the functional configuration of a bearer control unit [Diagram 3] Block diagram showing an example of the hardware configuration of a network node [Figure 4] Block diagram showing an example of the functional configuration of a GW [Diagram 5] A sequence diagram showing an example of a bearer establishment process [Figure 6] FIG. 1 shows bearer parameters managed by the bearer information management unit. [Figure 7] A sequence diagram showing an example of a bearer release process DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0011] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more features among the multiple features described in the embodiments may be arbitrarily combined. In addition, the same reference numbers are used for the same or similar configurations, and duplicated descriptions are omitted.

[0012] In this embodiment, in order to realize high-capacity communication by a user terminal (user equipment) (UE) (for example, high-capacity communication by an application installed in the UE), the mobile communication system is configured so that the UE can establish and use multiple bearers. In this specification, a bearer refers to each section of a communication path from a gateway (GW) via a base station to a UE.

[0013] In addition, in this embodiment, two types of bearers ("active bearer" and "standby bearer") are defined as bearers that a UE can establish. An "active bearer" refers to a bearer used for data transmission. A "standby bearer" is a bearer that is established as a bearer but cannot be used for data transmission, and can be switched to an active bearer by being activated. For example, when it becomes clear that there is a shortage of bandwidth and it becomes necessary to add a bearer for data transmission, a standby bearer that has been established in advance is activated. When establishing a bearer, as described later, it is necessary to perform a process of inquiring from multiple GWs in the core network about a GW that has the processing ability to handle data transmitted and received between the UE and the GW. On the other hand, in the case of activating a standby bearer, a GW has already been determined, and it is possible to omit the process of inquiring to multiple GWs in the core network. This makes it possible to add a bearer more quickly than by establishing a new bearer. In this embodiment, multiple bearers may be established between the same combination of base station and GW.

[0014] In this way, when the number of bearers established in advance for each UE becomes large, the number of active bearers among the bearers established for each GW may become small. In such a case, the number of standby bearers relative to the number of bearers that can be established for the GW becomes large, which may result in a decrease in the throughput of user data that can be transmitted and received for each GW and a decrease in the number of UEs that can be accommodated for each GW.

[0015] For this reason, the communication system according to this embodiment shares a bearer between the GW and the base station for multiple UEs. For example, when a bearer establishment request is received from a first UE, a communication path between the first UE and the GW is established, and a shared bearer between a predetermined base station and the GW is additionally established. Then, when a bearer establishment request is received from the first UE or another UE connected to the predetermined base station, a bearer between the UE and the base station is established in association with the already established shared bearer. This can reduce the delay in establishing a bearer between the base station and the GW after receiving a bearer establishment request from the UE. This also makes it possible to quickly establish a bearer using a shared bearer without having to establish a standby bearer for each UE in advance. This can reduce the number of standby bearers that the GW holds in advance for each UE. In addition, since the shared bearer can be assigned to a different UE after release, the load on the GW can be reduced more than if multiple standby bearers were established for each UE. In this embodiment, a dedicated bearer is also established as a type of bearer dedicated to a specific UE. A dedicated bearer is a bearer for which the UE to which it is assigned is predetermined, regardless of whether it is in an active or standby state.

[0016] <Mobile communication system configuration> Fig. 1 shows an example of the configuration of a mobile communication system according to this embodiment. As shown in Fig. 1, a mobile core 30 according to this embodiment includes a mobility management function (mobility management unit) 31, a bearer control function (bearer control unit) 32, and multiple GWs 33. The bearer control unit 32 according to this embodiment is an example of a network device arranged in a core network (mobile core 30) that determines, for a UE that can be connected to multiple base stations, the base station and the GW that accommodate each of the multiple bearers that the UE establishes for data communication.

[0017] The mobile communication system includes a plurality of radio base stations (base stations). In one example, a cell-free architecture may be applied to the mobile communication system, and a plurality of access points (APs) may be applied as a configuration for providing the functions of a radio base station. The plurality of base stations 20 are connected to a mobile core 30. Therefore, the UE 10 can connect to the plurality of base stations 20, access the mobile core 30 via the connected base stations 20, and further access the data network 40.

[0018] The bearer control unit 32 is configured to manage user session information, and to establish and release bearers, which are communication paths. In this embodiment, the bearer control unit 32 establishes bearers so that the bearers used by the UE 10 for data transmission are accommodated in the base station 20 and the GW 33. The bearer control unit 32 is also configured to determine the number of dedicated bearers to be established when the UE 10 is connected, select the accommodation destination of each established bearer, and determine bearer type switching. The bearer control unit 32 also determines the GW 33 for which a shared bearer should be reserved, determines the number of shared bearers to be reserved for each GW 33, and manages the shared bearers reserved for each GW.

[0019] <Configuration of Bearer Control Unit 32> 2 is a block diagram showing an example of a functional configuration of the bearer control unit 32. As shown in FIG. 2, the bearer control unit 32 includes a control signal receiving unit 201, a GW determining unit 202, a GW control unit 203, a bearer information management unit 204, and a communication unit 205.

[0020] The control signal receiving unit 201 receives control signals including a connection request, a bearer establishment request, and a bearer release request from the UE 10. It may also receive a notification of transition to an idle state from the UE 10. The connection request is a signal that requests a connection to the mobile core 30 when the UE 10 is powered on. In this embodiment, since a dedicated bearer is established at the time of a connection request, the bearer control unit 32 treats the connection request as one of the bearer establishment requests. The bearer addition request is a signal that is transmitted when the UE 10 requests a higher throughput or in response to the start of a specific application, and requests the establishment of an additional bearer to the UE 10, and is one of the bearer establishment requests. The bearer release request is a signal that is transmitted when the throughput request is lowered or in response to the end of a specific application, and requests the release of a bearer associated with the UE 10.

[0021] The GW determination unit 202 determines the GW to be controlled based on the control signal received by the control signal receiving unit 201. For example, when a connection request is received from the UE 10, the GW determination unit 202 determines the GW 33 that accommodates the UE 10, that is, the GW 33 that establishes the dedicated bearer, and when a shared bearer is instructed to be secured by a process described later, the GW determination unit 202 determines the GW 33 that secures the shared bearer. Also, for example, when a bearer establishment request is received from the UE 10 having a dedicated bearer in a standby state, the GW 33 that secures the dedicated bearer in a standby state is specified in order to transition the dedicated bearer in the standby state to the active state. Also, for example, when a bearer establishment request is received from the UE 10 not having a dedicated bearer in a standby state, the GW determination unit 202 instructs one of the GWs 33 that secures the shared bearer to establish a bearer between the UE and the base station in association with the shared bearer. Also, when a control signal for transitioning to a power-off state or an airplane mode-on state is received from the UE 10, all the dedicated bearers in the active state for the UE 10 may be set to a standby state and all the shared bearers may be released.

[0022] The GW control unit 203 instructs the GW 33 determined by the GW determination unit 202 to control a dedicated bearer or a shared bearer. For example, the GW control unit 203 instructs the establishment, release, or transition to an active state or a standby state of a dedicated bearer or a shared bearer. When the GW control unit 203 receives a request to release a shared bearer from the UE 10, the GW control unit 203 releases the bearer between the UE 10 and the base station 20 and also instructs whether to release or maintain the bearer between the base station 20 and the GW 33. The GW control unit 203 also instructs the GW 33 determined by the GW determination unit 202 to control the shared bearer. For example, the GW control unit 203 instructs the reservation and release of a shared bearer.

[0023] The bearer information management unit 204 manages parameters related to a dedicated bearer or a shared bearer, for example, by associating the bearer identifier with the bearer identifier, and manages information related to the identifier of the network device forming the bearer and information related to the state of the bearer.

[0024] FIG. 6 shows bearer information (bearer parameters) managed by bearer information management section 204 according to this embodiment.

[0025] The parameters related to the bearer include a bearer identification (ID) 601, a UE ID 602, a base station ID 603, a GW ID 604, status information 605, and a bearer type 606. The bearer identification 601 is an identifier of the bearer in the core network. The UE ID 602 ​​is identification information indicating the UE to which the bearer is assigned, and is, for example, the IP address of the UE 10. The base station ID 603 is an identifier of the base station 20 to which the UE 10 indicated by the UE ID 602 ​​is connected, and is, for example, the IP address of the base station. The GW ID 604 is identification information of the GW 33 that accommodates the bearer, and is, for example, the IP address (inner IP address) of the GW 33. The status information 605 indicates whether the bearer is in an active state or a standby state. The bearer type 606 indicates whether the bearer is a dedicated bearer or a shared bearer.

[0026] Entry 611 is an example of a dedicated bearer in an active state, entry 612 is an example of a dedicated bearer in a standby state, entry 613 is an example of a shared bearer that has been assigned to a UE 10 in an active state, entry 614 is an example of a shared bearer that has been assigned to a UE 10 in a standby state, and entry 615 is an example of a shared bearer that has not been assigned to a UE 10.

[0027] Here, the dedicated bearer and the shared bearer are assigned to the UE 10, the base station 20, and the GW 33. For this reason, bearer identification information (ID) 601, a UE ID 602, a base station ID 603, and a GW ID 604 are set. Whether the dedicated bearer and the shared bearer are in an active state or a standby state can be specified by status information 605.

[0028] On the other hand, for a shared bearer that has not been assigned to UE 10, bearer identification information (ID) 601, base station ID 603, and GW ID 604 are set, and no value is set (NULL) or a predetermined value (for example, 0) is set for UE ID 602.

[0029] In the example of FIG. 6, a flag for identifying whether the bearer is a dedicated bearer or a shared bearer is additionally managed as a parameter related to the bearer. However, it may be possible to identify whether the bearer is a dedicated bearer or a shared bearer based on the IP address range of the GW ID 604.

[0030] It should be noted that the GW 33 only needs to manage bearer parameters whose GW ID 604 matches that of the GW 33, and does not need to manage bearer parameters of other GWs 33. On the other hand, the bearer control unit 32 manages bearer parameters of multiple GWs 33 in the mobile core 30.

[0031] The GW 33 and the bearer control unit 32 share, for each bearer, the GW and bearer parameters corresponding to the GW ID 604. This enables the GW 33 to determine whether or not a shared bearer has been assigned to the UE 10.

[0032] Furthermore, the bearer control unit 32 holds the following information in the storage 304 (FIG. 3):

[0033] -GW load information -NW configuration (network configuration) information The NW configuration information is an example of network configuration information related to the base station 20 and the multiple GWs 33, and includes, for example, the NW topology, the radio link capacity, and the link capacity between the base station and the GW. The link capacity between the base station and the GW may be statically set. The GW load information may include information indicating the free capacity (free link capacity) of the GW. The GW load information may include at least one of the number of UEs 10 currently accommodated by the GW 33, the number of bearers currently accommodated by the GW 33, the communication speed of the user data communication provided by the GW 33 to the UE 10, and the number of shared bearers secured by the GW 33 and not assigned to the UE 10. The bearer control unit 32 may have the maximum number of UEs 10 that each GW 33 can accommodate, the maximum number of bearers that the GW 33 can accommodate, and the maximum communication speed of the user data communication provided by the GW 33 to the UE 10 as the NW configuration information, or may receive them as the load information.

[0034] Furthermore, the bearer control unit 32 periodically acquires and holds GW load information indicating the load occurring in the GW 33 from each GW 33. The acquisition period of the GW load information is set according to the operator's policy (for example, every 30 seconds).

[0035] In addition, each function of the bearer control unit 32 may be included in any of the network functions within the mobile core 30.

[0036] When the bearer control unit 32 is configured as a general-purpose server, as an example, it has a hardware configuration as shown in FIG. 3. Specifically, the bearer control unit 32 includes a CPU 301, a ROM 302, a RAM 303, a storage device (storage) 304 such as an HDD, and a communication interface (IF) 305. Note that network nodes other than the bearer control unit 32 may also have the hardware configuration shown in FIG. 3.

[0037] In the bearer control unit 32, for example, a program for realizing each of the above functions stored in any one of the ROM 302, the RAM 303, and the storage device 304 is executed by the CPU 301. Note that the CPU 301 may be replaced by one or more processors such as an ASIC (application-specific integrated circuit), an FPGA (field-programmable gate array), or a DSP (digital signal processor). By executing the above-described program, the CPU 301 can execute the communication control method described later with reference to FIGS. 5 and 7. The communication IF 305 is a communication interface for communicating with an external device under the control of the CPU 301. The bearer control unit 32 may have a plurality of communication IFs 305 with different connection destinations.

[0038] Note that the bearer control unit 32 may be provided with dedicated hardware for executing each function described in this specification, or may execute a part of the functions by hardware and execute the other parts by a computer that operates a program. Also, all functions may be executed by a computer and a program.

[0039] <Configuration of GW> FIG. 4 is a block diagram showing a functional configuration example of GW33. In addition to existing functions (not shown) related to the transmission of user data between the base station 20 and the data network 40, GW33 includes a load monitoring unit 401, a load notification unit 402, a communication unit 403, and a bearer management unit 404. The load monitoring unit 401 monitors the load occurring in GW33 and outputs load information indicating the load. The load notification unit 402 notifies the bearer control unit 32 of the load information output from the load monitoring unit 401 at a predetermined notification frequency. This notification frequency is set according to the operator's policy. The bearer management unit 404 establishes and releases bearers for the UEs 10 accommodated by GW33 based on the control signal received from the bearer control unit 32. In addition, the bearer management unit 404 manages the bearers established by GW33 based on the control signal received from the bearer control unit 32.

[0040] <Function of UE> In the mobile communication system of this embodiment, the UE 10 has the following functions. When starting a large-capacity communication such as communication by an application (hereinafter referred to as "app"), the UE 10 transmits a bearer establishment request for establishing one or more base stations and a plurality of bearers to the mobile core 30. The UE 10 includes the following information in the request message to be transmitted.

[0041] - The desired number of bearers - A list of base stations to which the UE 10 can connect The desired number of bearers may be, for example, the communication speed required by the UE 10, or the difference between the communication speed required by the UE 10 and the current communication speed. That is, when the bearer control unit 32 receives a bearer establishment request, it is only necessary to be able to specify the number of bearers to be established.

[0042] The list of base stations to which the UE 10 can connect includes the identification information of one or more base stations 20 received by the UE 10 and information indicating communication quality such as the reference signal strength received from the base station. In one example, the list of base stations to which the UE 10 can connect may include information indicating the data transmission band between the UE 10 and the base station 20.

[0043] Also, UE10 transmits a connection request to the core network via one base station when starting up or when the in-flight mode is off. The connection request includes the identifier of UE10. Using the connection request, the bearer control unit 32 allocates one or more dedicated bearers as permanent active bearers to UE10. In one example, one dedicated bearer in the active state and one or more dedicated bearers in the standby state may be allocated.

[0044] When establishing a bearer, UE10 receives from the mobile core 30 the expected communication speed value for each bearer and stores it. If UE10 determines that it cannot achieve the expected communication speed value saved by the current active bearer, such as when starting an application that performs high-capacity communication, it notifies the bearer control unit 32 of the mobile core 30 to that effect. Due to this notification, the bearer control unit 32 starts the bearer addition process for UE10 (in the procedure of FIG. 5 described later).

[0045] Also, an application installed on UE10 (hereinafter also referred to as the "terminal application") has a desired communication speed set. The terminal application has a function of cooperating with UE10 and including information indicating the desired communication speed in the request message when transmitting a bearer establishment request.

[0046] <Flow of Bearer Establishment Process> Subsequently, with reference to FIG. 5, the connection process and bearer addition process of UE10 in the mobile communication system according to the present embodiment will be described.

[0047] First, in S501, UE10 transmits a connection request for connecting to the mobile communication system to the base station 20 triggered by powering on or turning off the in-flight mode. The connection request can detect a broadcast signal transmitted from the base station 20 and identify the parameters for connecting to the base station 20 included in the broadcast signal. The base station 20 transfers the received connection request to the bearer control unit 32.

[0048] Next, the bearer control unit 32 inquires about the load of the GW 33 in order to establish a permanent dedicated bearer in S502. In S503, the GW 33 generates the above-mentioned load information such as the number of currently connected UEs 10, and transmits a load information response including the load information to the bearer control unit 32 in S504.

[0049] The bearer control unit 32 that has acquired the load information determines which GW 33 should accommodate the UE 10 based on the load information of the GW 33 received in S504 (S505). For example, in S505, the bearer control unit 32 may determine to accommodate the UE 10 in a GW 33 that has a small free capacity (free link capacity), a small number of UEs 10 currently accommodated, a small number of bearers currently accommodated, or a small communication speed of user data communication provided to the UE 10.

[0050] Next, in S506, the bearer control unit 32 transmits a bearer establishment request for establishing a bearer between the UE and the base station to the base station 20. This bearer establishment request includes a bearer ID, a bearer type (active bearer or standby bearer), a GW ID, and an expected communication speed. Note that if the base station 20 rejects the bearer establishment request, the following S507 and S508 are skipped.

[0051] In S507, the base station 20 transmits a bearer establishment request to the UE 10. This bearer establishment request includes a bearer ID and a bearer type. The UE 10 stores the bearer ID at the timing of receiving the bearer establishment request. The UE 10 can transmit a bearer release request, which will be described later, based on the stored information. In addition, when a standby bearer is established, the UE 10 can use the bearer ID to transmit a bearer activation request.

[0052] In S508, the UE 10 attempts to establish a bearer in accordance with the received bearer establishment request, and transmits a bearer establishment response indicating the result to the base station 20. If the bearer establishment is successful, this bearer establishment response includes a bearer ID and a bearer establishment result. In response to receiving the bearer establishment response from the UE 10, the base station 20 transmits a bearer establishment response indicating the result of the bearer establishment between the UE and the base station to the bearer control unit 32 in S509. Here, if the bearer establishment between the UE and the base station fails, the following S510 and S511 are skipped.

[0053] Next, in S510, the bearer control unit 32 transmits a bearer establishment request for establishing a bearer between the base station and the GW to the GW 33. This bearer establishment request includes a bearer ID, a bearer type, and a base station ID.

[0054] In S511, the GW 33 attempts to establish a bearer according to the received bearer establishment request, and transmits a bearer establishment response indicating the result to the bearer control unit 32. If the bearer establishment is successful, the bearer establishment response includes a bearer ID and a bearer establishment result. If the bearer establishment fails due to the cause of the GW 33, the bearer establishment response also includes a cause value indicating that fact.

[0055] When the bearer is established, the bearer control unit 32 notifies the UE 10 in S512 that the bearer has been established. The notification in S512 includes the bearer ID and the result of the bearer establishment.

[0056] In this manner, by establishing the bearer in steps S506 to S512, the UE 10 can connect to the mobile communication network and can receive data communication services with an external network via the GW 33.

[0057] As described above, when multiple dedicated bearers are established when the UE 10 is connected, the processes of S506 to S512 are repeated. For example, when multiple dedicated bearers are established when the UE 10 is connected, the processes of S506 to S512 are repeated for each UE-base station corresponding to the dedicated bearer. Here, when multiple dedicated bearers are established when the UE 10 is connected, all of the established bearers may be transitioned to a standby state. Also, when the UE 10 establishes multiple bearers, a combination of multiple base stations 20 and multiple GWs 33 may be used.

[0058] Next, in S513, the bearer control unit 32 determines whether or not to instruct the establishment of a shared bearer for the GW33 with which the UE10 has established a dedicated bearer. The process of S513 includes a process of determining whether or not to establish a shared bearer between any of the GW33 and any of the base stations. For example, a shared bearer may be established as a backup communication path for the base station 20 and the GW33 with which the dedicated bearer has been established based on the connection request of S501. As described above, whether or not the bearer control unit 32 instructs the GW33 to secure a shared resource may be determined based on a combination of the following parameters.

[0059] - Number of bearers per UE accommodated n t - Average communication speed per UE10 currently accommodated by GW33 c a -Maximum number of UEs that can be accommodated in GW33a t - The number of UEs 10 currently accommodated by GW 33 t -The maximum overall data communication speed that the GW33 can provide to the UE g -The overall data communication speed currently provided by GW33a g - Number of base stations connected to GW33 b - The connection frequency r of UE 10 in a given period t - The frequency s of bearer establishment requests transmitted from UE 10 accommodated by GW 33 in a given period t - The frequency t of bearer release requests transmitted from UE 10 accommodated by GW 33 in a given period t - Proportion of active bearers among bearers accommodated by GW33 -Number of shared bearers that have not been assigned to UE 10 accommodated by GW 33 Number of shared bearers not assigned to UE 10 per base station For example, the number of bearers per UE is n t If n is large, it is likely that many bearers will be allocated to the newly connected UE. Therefore, the number of bearers per UE accommodated, n t If the ? ? is greater than a predetermined threshold, it may be determined to indicate establishment of a shared bearer.

[0060] In addition, the average total communication speed per UE10 is c a Even if the average total communication speed per UE 10 is large, it is possible that the communication speed of the newly connected UE 10 will also be high. a If the ? ? is greater than a predetermined threshold, it may be determined to indicate establishment of a shared bearer.

[0061] In addition, the maximum number of UEs that can be accommodated in GW33 is a t When is large, the number of UEs 10 currently accommodated by the GW 33, u t When a is small, it is considered that the load processing capacity of the GW 33 is sufficient. Therefore, the upper limit a t is greater than a predetermined threshold, or the number of UEs 10 currently accommodated by the GW 33, u t If the maximum data communication speed t g is greater than a certain threshold, or the data communication speed currently provided by GW33 is gIf the difference is smaller than a predetermined threshold, the bearer control unit 32 may also determine to instruct the establishment of a shared bearer.

[0062] In addition, the number of base stations connected to GW33 is n b is smaller than a predetermined threshold, the connection frequency r t is greater than a predetermined threshold, the frequency s at which a bearer establishment request is transmitted from a UE 10 accommodated by the GW 33 in a predetermined period t is greater than a predetermined threshold, the frequency t t is smaller than a predetermined threshold, or the ratio of active bearers among the bearers accommodated by the GW 33 is larger than a predetermined threshold, the probability that establishment of a shared bearer is requested is also considered to be high. In such a case, the bearer control unit 32 may determine to instruct establishment of a shared bearer.

[0063] Furthermore, if a large number of shared bearers not assigned to UE 10 are established in some base stations, there is a possibility that processing resources will be wasted, such as the base station 20 being unable to accommodate the UE 10 due to limitations on the number of bearers. For this reason, the bearer control unit 32 may make the number of shared bearers not assigned to UE 10 equal for each base station 20. Furthermore, the base station 20 may determine a base station for establishing a shared bearer such that the number of shared bearers not assigned to UE 10 relative to the number of bearers that the base station 20 can establish with the GW 33 falls within a predetermined range.

[0064] In one example, the number of shared bearers not assigned to the UE may be determined for each GW 33 by combining the above parameters. For example, the lower limit number of shared bearers that the GW 33 reserves in advance may be set to 1. b The number of shared bearers that the GW 33 should reserve and that are not assigned to the UE 10 is b n of b n = max[l b , min{u b ,f 1 n t(c a -u t )a t (t g -a g )n b r t s t / t t}] Here, max[a,b] is a function that selects the larger value of a and b, and min[a,b] is a function that selects the smaller value of a and b. 1 is a coefficient that specifies the amount of shared bearer to be reserved for each mobile communication system. In one example, <f 1 <1.

[0065] Next, in S514, the bearer control unit 32 requests the GW33 to establish a shared bearer. The shared bearer reservation instruction transmitted in S514 includes the bearer ID and base station ID determined by the bearer control unit 32. The GW33 that receives the shared bearer reservation instruction in S514 establishes a shared bearer with the base station corresponding to the base station ID included in the shared bearer establishment request, and transmits a shared bearer reservation response to the bearer control unit 32 in S515. The reservation response includes information indicating the reserved shared bearer. For example, when the inner IP address of the GW33 is reserved as the shared bearer, the reserved IP address may be notified. Next, in S516, the bearer control unit 32 and the GW33 store information indicating the established bearer as a bearer parameter, and update the bearer information. At the time of S516, since the allocation to the UE10 has not been performed, the UE ID has not been set as shown in entry 615 in FIG. 6. Furthermore, the GW33 increases the number of bearers established by the GW33 in the load information of the GW33. In one example, the GW33 may update other parameters of the load information based on the established shared bearer. For example, the GW33 may update the load information by reducing the communication speed that can be provided by the secured shared bearer from the free link capacity of the GW33. This allows the GW33 side to secure in advance a communication band that can be used for the shared bearer when the UE10 is connected.

[0066] Thereafter, when the UE 10 determines that a bearer needs to be added because, for example, execution of a specific application or stop of an increase in the window size of TCP communication has occurred, the UE 10 transmits a request to add a bearer to the bearer control unit 32 in S517. As described above, a shared bearer using a shared resource can be used by multiple UEs 10. For this reason, in this embodiment, the description will be given assuming that a request to add a bearer is issued by an already connected UE 11. However, the request to add a bearer may be transmitted by the UE 10.

[0067] The bearer addition request transmitted in S517 includes identification information of the UE 11. In one example, the bearer addition request may include information indicating either an active state or a standby state as a state of the bearer to be added. Also, the bearer addition request may include information indicating the number of bearers to be added by the UE 11.

[0068] The bearer control unit 32 that has received the bearer addition request determines the GW33 that will establish a bearer with the UE 11 in S518. In one example, the GW33 that will establish a bearer with the UE 11 may be determined based on load information of the GW33 that has already established a dedicated bearer with the UE 11. In another example, the GW33 that will establish a bearer with the UE 11 may be determined based on load information of the GW33 from among the GW33 that has not established a bearer with the UE 11. In another example, the GW33 may be determined based on the type of application that the UE 11 is running.

[0069] 5, UE 11 is illustrated as transmitting the bearer addition request to the same base station as UE 10, but UE 11 may transmit the bearer addition request to a base station 21 different from UE 10. In this case, if the base station 21 that receives the bearer addition request from UE 11 and GW 33 have secured a shared bearer that has not been assigned to a UE, a bearer between the base station 21 and UE 11 can be established in association with the shared bearer.

[0070] Next, the bearer control unit 32 selects one of the shared bearers associated with the ID of the determined GW33, identifies the bearer ID, and executes the bearer establishment process described with reference to S506 to S512 in S519. Here, in S519, a bearer establishment request including a bearer ID of a bearer parameter corresponding to the shared bearer secured in S514 is transmitted, so that the GW33 can be instructed to establish the shared bearer. In one example, in S519, the processes corresponding to S510 and S511 may be omitted, and instead, a control signal requesting an update of the bearer parameter may be transmitted from the bearer control unit 32 to the GW33. In addition, the bearer control unit 32 transmits a bearer establishment request between the UE and the base station to the base station 20, including information specifying a shared bearer between the base station and the GW33. As a result, the base station 20 forms an IP tunnel by connecting the bearer between the UE and the base station and the bearer between the base station and the GW. That is, the bearer control unit 32 associates the UE 10 with the shared bearer and establishes a bearer between the UE and the base station in association with the shared bearer, thereby making it possible to establish a communication path using the shared bearer.

[0071] This makes it possible to instruct the establishment of a communication path between the UE 10 and the GW 33 using a shared bearer. That is, after receiving a bearer establishment request, a communication path between the UE 10 and the GE 33 can be established without the process of establishing a bearer between the base station and the GW, so that a processing delay can be suppressed.

[0072] Furthermore, the shared bearer can be used for different UEs 10. This allows the GW 33 and the bearer control unit 32 to reduce the number of bearers established for each UE.

[0073] As described above, the bearer control unit 32 according to this embodiment establishes a bearer between the base station and the GW that is not associated with the UE in advance, and when a bearer establishment request is received from the UE after the bearer is established, the bearer control unit 32 instructs the base station to establish a bearer between the UE and the base station in association with the bearer between the base station and the GW that is not associated with the UE. This makes it possible to establish a communication path from the UE to the GW with less delay than when a bearer between the base station and the GW is established after a bearer establishment request is received from the UE. In addition, compared to a configuration in which a bearer is established in advance for each UE, a bearer that can be shared by multiple UEs can be reused, and therefore the number of bearers accommodated by the GW can be reduced.

[0074] In the present embodiment, the bearer control device 32 has been described as determining whether or not to establish a shared bearer in the GW 33 at the timing of receiving a connection request from the UE 10. However, the bearer control device 32 may determine whether or not to establish a shared bearer at any timing, for example, may determine whether or not to establish a shared bearer for the GW 33 that has transmitted the load information at the timing of receiving load information from the GW 33. Alternatively, the bearer control device 32 may determine whether or not to establish a shared bearer when receiving a bearer addition request from the UE 10.

[0075] <Bearer release process> Next, the bearer release process will be described with reference to FIG.

[0076] First, in S701, the UE 10 transmits a bearer release request to the bearer control unit 32 when the UE 10 is powered off, airplane mode is turned on, a predetermined application is terminated, or the like is used as a trigger. The bearer release request includes identification information of the UE 10. In one example, the bearer release request includes the bearer ID to be released. Alternatively, a control signal requesting the release of all bearers may be transmitted.

[0077] Upon receiving a bearer release request, the bearer control unit 32 identifies the bearer to be released based on the bearer release request at S702, and the GW 33 that accommodates the bearer. For example, when a release request including a bearer ID is received at S701, the GW 33, base station 20, and UE 10 corresponding to the bearer ID can be identified based on the bearer parameters stored in the storage 304. In another example, the release request from the UE 10 may not include a bearer ID and may include the identification information of the UE 10. In this case, the bearer control unit 32 may determine to release the bearers having a UE ID that matches the identification information of the UE 10 in a predetermined order. For example, shared bearers may be preferentially released, or bearers accommodated by a GW 33 in a high load state may be preferentially released based on the load information of the GW 33. In the example after S702, the processing when it is determined to release a bearer established using a shared bearer will be described.

[0078] When it is determined at S702 to release the bearer between the UE 10 and the GW 33, the bearer control unit 32 determines whether to release the shared bearer or keep it reserved. In other words, the bearer control unit 32 that has received the bearer release request determines whether to release all sections from the UE to the GW or only the section between the UE and the base station among the sections from the UE to the GW. For example, for the GW 33 that accommodates the shared bearer associated with the bearer between the UE and the base station for which release is requested, the bearer control unit 32 determines the number of shared bearers to be reserved as described in S513. Then, when the number of currently reserved shared bearers not associated with the UE is greater than the number of shared bearers to be reserved, it may be determined to release the bearer between the UE and the base station and the associated shared bearer. On the other hand, when the amount of currently reserved shared bearers not associated with the bearer between the UE and the base station is less than or equal to the number of shared bearers to be reserved, it may be determined to release the bearer between the UE and the base station but maintain the shared bearer.

[0079] Below, the processing of S704 to S710 is bearer release processing A when it is determined that the bearer between the UE and base station is to be released and the shared bearer is to be released as well, and the processing of S714 to S720 is bearer release processing B when it is determined that the bearer between the UE and base station is to be released but the shared bearer between the base station and GW is to be maintained.

[0080] In S704, the bearer control unit 32 transmits a bearer release request to the base station 20. The bearer release request includes a bearer ID. In S705, the base station 20 transfers the bearer release request to the UE 10 corresponding to the bearer ID. In S706, the UE 10 transmits a bearer release response in response to the bearer release request, and releases the bearer by deleting the bearer information corresponding to the bearer ID included in the bearer release request from the list of bearers stored in the UE 10. In S707, the base station 20 transmits the bearer release response to the bearer control unit 32. As a result, the bearer between the UE and the base station is released.

[0081] Next, in S708, the bearer control unit 32 transmits a bearer release request to the GW 33 associated with the bearer ID, and the GW 33 transmits a bearer release response to the bearer control unit 32 in S709.

[0082] When receiving the shared bearer release response in S709, the bearer control unit 32 and the GW 33 delete the entry corresponding to the released shared bearer from the bearer parameters stored in the storage 304.

[0083] When the shared bearer is released, the bearer control unit 32 transmits a bearer release notification to the UE 10 in S710.

[0084] Next, the processing of S711 to S712 is the same as S701 and S702, so the description will be omitted. In S713, the bearer control unit 32 releases the bearer between the UE and the base station, but decides to maintain the shared bearer between the base station and the GW. In this case, the bearer release processing B of S714 to S720 is executed.

[0085] In the bearer release process B, the processes of S714 to S717 are similar to those of S704 to S707 in the bearer release process A, and therefore a description thereof will be omitted. Next, in S718, the bearer control unit 32 notifies the GW 33 that the bearer between the UE and the base station has been released. Upon receiving the notification, the GW 33 transmits a notification response to the bearer control unit 32 in S719 without releasing the shared bearer. In this case, the bearer control unit 32 and the GW 33 release the association of the bearer requested to be released with the UE as shown in 615 in FIG. 6, but do not delete the entry.

[0086] The UE 10 that has received the bearer release notification in S720 deletes the shared bearer that has been requested to be released from the list of bearers stored in the UE 10. This allows the GW 33 side to maintain the shared bearer while releasing the association of the bearer between the UE 10 and the base station. In one example, the bearer control unit 32 and the GW 33 may set the bearer corresponding to the notification to a standby state.

[0087] <Other embodiments> The network device (bearer control unit 32) according to the above embodiment can be realized by a computer program for causing a computer to function as a network device. The computer program can be stored in a computer-readable storage medium and distributed, or can be distributed via a network.

[0088] In this embodiment, the mobile core is described as being capable of establishing a dedicated bearer and a shared bearer. However, only a shared bearer may be established. In such a case, the bearer control unit 32 that receives a connection request from the UE 10 establishes a plurality of bearers between the UE 10 and the GW 33, and when a bearer release request is received from the UE 10, determines whether or not to release the bearer between the base station and the GW as a shared bearer for each bearer, and when a bearer addition request is received from another UE, may establish a bearer between the UE and the base station in association with the bearer between the base station and the GW. In such a case, the bearer control unit 32 and the GW 33 may not manage the bearer type as bearer information. That is, the bearer control unit 32 may allocate a shared bearer to a connection request transmitted from the UE 10, or may allocate a shared bearer to a bearer addition request transmitted from the UE 10.

[0089] In this embodiment, the bearer control unit 32 establishes a shared bearer not associated with the UE between GW33 and a predetermined base station 20, and has been described as associating the UE with the shared bearer in response to a bearer establishment request from the UE10 and establishing a bearer between the UE and the base station. In one example, the bearer control unit 32 may pre-reserve the shared resources used to establish a shared bearer with the base station, and establish a bearer using the shared resources in response to a bearer establishment request from the UE. For example, the shared resources are at least one of an IP address and an occupied communication band. The bearer control unit 32 transmits an instruction to reserve shared resources by specifying a bearer ID, and GW33 transmits the reserved IP address associated with the bearer ID to the bearer control unit 32 as a response. That is, in S514 and S515 of FIG. 5, an instruction to reserve shared resources is transmitted and a response to the instruction to reserve shared resources is exchanged. Then, the bearer control unit 32 and GW33 store the bearer ID and the IP address as bearer information. In this case, the bearer ID and the IP address, which are shared resources, are not associated with the UE10 and the base station 20. When the bearer control unit 32 determines to use the shared resources, the bearer control unit 32 transmits a bearer establishment request to GW33 by specifying the bearer ID corresponding to the shared resources and the base station 20 that establishes the bearer. GW33 that has received the establishment request establishes a bearer with the base station 20 specified in the establishment request and the bearer ID specified. Thereby, the time for the bearer control unit 32 to acquire the load information of GW33 in response to a bearer establishment request from the UE10 can be reduced. Also, when releasing a bearer while reserving the shared resources, GW33 releases the bearer but stores that the IP address has been assigned to the bearer or stores that the communication band is in use. Then, when instructed to establish a bearer using the shared resources, the bearer is established using the resources. Thereby, when receiving a bearer establishment request, there is no need for the bearer control unit 32 to check whether GW33 has resources to establish a bearer. Also, the shared resources can be shared between the GW and the base station, and the number of bearers established between the GW and the base station can be reduced.

[0090] The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention. [Explanation of symbols]

[0091] 10: UE, 20: AP, 30: Mobile core, 31: Mobility management function, 32: Bearer control unit, 33: GW

Claims

1. A network device disposed in a core network, which determines a base station and a gateway (GW) accommodating each of a plurality of bearers established by a user terminal (UE) for data communication, A receiving means for receiving a bearer establishment request; A control means for controlling bearers accommodated in a plurality of GWs in the core network; Equipped with The control means In response to receiving a connection request from a first UE, instruct the first GW to establish a first bearer between the first GW of the plurality of GWs and a first base station of a plurality of base stations in the core network; After establishing the first bearer, determine whether to establish an additional bearer between the first GW and the first base station, the additional bearer being not associated with a UE; Instruct the first GW to establish a second bearer when it is determined that an additional bearer is to be established; Instructing the first GW to establish the second bearer, and then instructing the first base station to establish a predetermined bearer between the first UE and the first base station in association with the second bearer in response to receiving a bearer addition request from the first UE by the receiving means. A network device comprising:

2. The control means In response to receiving a connection request from a second UE different from the first UE by the receiving means, determine whether to establish an additional bearer not associated with the UE between the first GW and the first base station; Instruct the first GW to establish the second bearer when it is determined that an additional bearer is to be established; 2. The network device according to claim 1, further comprising: a first base station that is connected to the first GW and that is connected to the first base station, and that is connected to the first UE and the first base station, and that is connected to the first base station and that is connected to the first GW and the first base station, in response to receiving a request to add a bearer from a first UE at the receiving means after instructing the first GW to establish the second bearer.

3. 3. The network device according to claim 1, wherein the control means, when determining to establish an additional bearer, establishes a plurality of the second bearers not associated with a UE between at least one of the plurality of GWs and at least one of the plurality of base stations.

4. Further comprising an acquisition means for acquiring load information indicating a load occurring in each of the plurality of GWs from each GW, 4. The network device according to claim 1, wherein the control means determines the first GW and the first base station for establishing the second bearer based on the loads of each of the plurality of GWs acquired by the acquisition means.

5. The control means The amount of resources for establishing a bearer reserved by each of the plurality of GWs; The maximum number of UEs that each of the plurality of GWs can accommodate; The number of UEs accommodated in each of the plurality of GWs; The average communication speed of UEs accommodated in each of the plurality of GWs, The frequency of bearer establishment requests received from UEs accommodated by each of the plurality of GWs in a predetermined period of time; The frequency of bearer release requests received in a predetermined period from UEs accommodated by each of the plurality of GWs; The maximum communication speed of the entire data communication that each of the plurality of GWs can provide; The overall data communication speed currently provided by each of the plurality of GWs, and The number of base stations connected to each of the plurality of GWs, The network device according to claim 4, characterized in that it determines which GW to instruct to establish a bearer not associated with the UE based on at least one of the above.

6. 6. The network device according to claim 4 or 5, characterized in that after the control means establishes the predetermined bearer between the first UE and the first base station, it determines whether to release the second bearer in response to a bearer release request received from the first UE.

7. 7. The network device according to claim 6, wherein when the control means receives a bearer release request from the first UE, the control means determines whether to release the second bearer based on the number of bearers between the first GW and the plurality of base stations that are not associated with the UE and that are secured by the first GW.

8. The control means The amount of resources for establishing a bearer reserved by the first GW; The maximum number of UEs that the first GW can accommodate; The number of UEs accommodated by the first GW; The average communication speed of the UE accommodated by the first GW; The frequency of bearer establishment requests received from UEs accommodated by the first GW in a predetermined period of time; The frequency of bearer release requests received from UEs accommodated by the first GW in a predetermined period of time; The maximum communication speed of the entire data communication that the first GW can provide The overall data communication speed currently provided by the first GW; and The number of base stations connected to the first GW, 8. The network device according to claim 7, wherein the network device determines whether to release the second bearer based on at least one of the above.

9. 9. The network device according to claim 8, wherein the load information includes at least any of the following: an available link capacity of each of the plurality of GWs; a number of UEs accommodated by each of the plurality of GWs; a number of active bearers established by each of the plurality of GWs; and a number of bearers between the first GW and a base station that are not associated with a UE and that are secured by each of the plurality of GWs.

10. A network device disposed in a core network, which determines a base station and a gateway (GW) accommodating each of a plurality of bearers established by a user terminal (UE) for data communication, A receiving means for receiving a bearer establishment request from the UE via the base station; A control means for controlling bearers accommodated in a plurality of GWs in the core network; Equipped with The control means In response to a bearer establishment request received from a first UE by the receiving means, a predetermined GW for accommodating a bearer is determined from among the plurality of GWs, a command is issued to the predetermined GW to establish a bearer between the first UE and the predetermined GW, and a command is issued to the predetermined GW to secure a predetermined resource that is not associated with either the UE or a base station for establishing a bearer; In response to receiving a bearer establishment request from a second UE different from the first UE, instruct to establish a predetermined bearer between the second UE and the predetermined GW using the predetermined resource. A network device comprising:

11. 11. The network device according to claim 10, wherein the predetermined resource for establishing a bearer is an IP address or an occupied communication band of the predetermined GW in the core network.

12. A user equipment (UE) that establishes a plurality of bearers for data communication under the control of a network device disposed in a core network including a plurality of base stations and a plurality of gateways (GWs), A transmission means for transmitting a bearer establishment request to the network device; a communication means for performing data communication using the plurality of bearers established in response to the establishment request; Equipped with The network device comprises: In response to receiving a bearer establishment request from the UE, instruct the first GW to establish a first bearer between a first GW of the plurality of GWs and a first base station of a plurality of base stations in the core network; After establishing the first bearer, determine whether to establish an additional bearer between the first GW and the first base station, the additional bearer being not associated with a UE; Instruct the first GW to establish a second bearer when it is determined that an additional bearer is to be established; instructing, in response to receiving a bearer addition request from a first UE, to establish a predetermined bearer between the first UE and the first base station in association with the second bearer. A user terminal comprising:

13. A communication control method executed by a network device disposed in a core network, the method determining a base station and a gateway (GW) accommodating each of a plurality of bearers established by a user terminal (UE) for data communication, the method comprising: In response to receiving a bearer establishment request from a first UE, instructing a first GW to establish a first bearer between a first GW of the plurality of GWs and a first base station of a plurality of base stations in the core network; After establishing the first bearer, determining whether to establish an additional bearer between the first GW and the first base station, the additional bearer being not associated with a UE; instructing the first GW to establish a second bearer if it is determined that an additional bearer should be established; Instructing the first base station to establish a predetermined bearer between the first UE and the first base station in association with the second bearer in response to receiving a bearer addition request from a first UE after instructing the first GW to establish the second bearer; A communication control method comprising:

14. A program for causing a computer included in a network device to execute each step of the communication control method according to claim 13.

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