CONTROL DEVICE, ACCESS NETWORK NODE, CONTROL METHOD, AND COMPUTER PROGRAM

Abstract

To have AN (Access Network) nodes stably perform congestion control when an AMF (Access and Mobility Management Function) is overloaded.SOLUTION: A second control device provided separately from a first control device that instructs an access network (AN) node to start congestion control includes: an information collection unit that collects predetermined information for congestion control from the AN node and the first control device; a determination unit that determines whether congestion control is necessary based on the information collected by the information collection unit; and a transmitting unit that transmits a congestion control start message instructing the AN node to start congestion control when the determination unit determines that congestion control is necessary.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a control device, an access network node, a control method, and a computer program. [Background technology]

[0002] Technical specifications for the fifth generation mobile communication system (5G system) are described in Non-Patent Documents 1 and 2. The technical specifications for the 5G system (5G specifications) stipulate that when an Access and Mobility management Function (AMF) falls into an overload state, the AMF executes Non-Access-Stratum (NAS) level congestion control, and when an Access Network (AN) node supports overload control, the AMF suppresses the load generated by the AN node (see Non-Patent Document 1, 5.19.5 "AMF Control Of Overload").

[0003] More specifically, the AMF transmits an "NGAP OVERLOAD START" message to all or some of the AN nodes to notify the AN node that its own AMF is in an overload state. The AN node that receives the "NGAP OVERLOAD START" message recognizes that the AMF that sent the "NGAP OVERLOAD START" message is in an overload state, and regulates traffic by rejecting signals that meet specific conditions among signals addressed to the AMF that sent the "NGAP OVERLOAD START" message. The AMF can include a signal regulation probability in the "NGAP OVERLOAD START" message. The AN node can use the regulation probability included in the "NGAP OVERLOAD START" message as the signal regulation probability in congestion control. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] 3GPP, “TS 23.501”, v17.2.0 [Non-Patent Document 2] 3GPP, “TS 38.413”, v16.8.0 Summary of the Invention [Problem to be solved by the invention]

[0005] In the conventional 5G specifications described above, if the AMF suddenly becomes overloaded due to a sudden increase in traffic, the AMF may fail to send the "NGAP OVERLOAD START" message, which may prevent the AN node from properly starting congestion control.

[0006] In addition, when the AMF falls into an overload state, even if the AMF can transmit the "NGAP OVERLOAD START" message, it is difficult for the AMF to calculate an appropriate value for the barring probability of the signal. This is because it is difficult for the AMF in an overloaded state to obtain information necessary for calculating the barring probability of the signal. The information necessary for calculating the barring probability of the signal is, for example, the number of signals per unit time transmitted from the AN node to the AMF. Since the AMF in an overloaded state cannot measure the number of signals per unit time, it is difficult for the AMF to calculate an appropriate value for the barring probability of the signal.

[0007] The present invention has been made in consideration of the above circumstances, and its purpose is to enable an AN node to stably perform congestion control when the AMF falls into an overload state. [Means for solving the problem]

[0008] (1) One aspect of the present invention is a second control device provided separately from a first control device that instructs an access network node (AN node) in a mobile communication system to start congestion control, a RAN controller that controls the AN node, the RAN controller transmitting the AN node information to the RAN controller; The first control device Information to be transmitted to a core controller that controls the first control device, For congestion control Second information andand an information collecting unit that collects the No. 1 information and the second information. a determination unit that determines the necessity of the congestion control based on the The RAN controller that collected the first information or A control device comprising: a transmitter that transmits a congestion control start message to the AN node to instruct the AN node to start congestion control. (2) One aspect of the present invention is the information collected by the information collecting unit. No. 1 information and the second information A parameter determination unit that determines a parameter to be used in the congestion control based on The transmission unit is the control device of (1) above, which, when the judgment unit judges that the congestion control is necessary, transmits a message to the AN node notifying the AN node of the parameters determined by the parameter determination unit. (3) One aspect of the present invention is a control device of either (1) or (2) above, wherein the transmission unit transmits a congestion control end message to the AN node instructing it to end congestion control when the determination unit determines that the congestion control is not necessary. (4) One aspect of the present invention is the information collected by the information collecting unit. No. 1 information and the second information the control device according to any one of (1) to (3) above, further comprising a resource expansion control unit that controls to expand resources available to the first control device based on the information collected by the information collection unit after the resources available to the first control device have been expanded by the control of the resource expansion control unit, and the determination unit determines the need for the congestion control based on the information collected by the information collection unit after the resources available to the first control device have been expanded by the control of the resource expansion control unit.

[0009] (5) One aspect of the present invention is an access network node (AN node) in a mobile communication system, comprising: a receiving unit that receives messages regarding congestion control from both a first control device that instructs the AN node to start congestion control and a control device (second control device) that is provided separately from the first control device and is any one of (1) to (4) above; and a congestion control unit that prioritizes one of the messages regarding congestion control received from the first control device and the messages regarding congestion control received from the second control device. (6) One aspect of the present invention is the access network node of (5) above, wherein the congestion control unit changes the restriction probability for a signal that is the subject of the congestion control depending on the priority of the signal.

[0010] (7) In one aspect of the present invention, a computer of a second control device, which is provided separately from a first control device that instructs an access network node (AN node) in a mobile communication system to start congestion control, is provided for the AN node. a RAN controller that controls the AN node, the RAN controller transmitting the AN node information to the RAN controller; The first control device Information to be transmitted to a core controller that controls the first control device, For congestion control Second information and and an information gathering step of gathering the information gathered by the information gathering step. No. 1 information and the second information. a determination step of determining whether the congestion control is necessary based on the above; and when the determination step determines that the congestion control is necessary, The RAN controller that collected the first information or A sending step of sending a congestion control start message to an AN node to instruct the AN node to start congestion control.

[0011] (8) One aspect of the present invention is a computer program for causing a computer of an access network node (AN node) in a mobile communication system to execute a receiving step of receiving messages regarding congestion control from both a first control device that instructs the AN node to start congestion control and a control device (second control device) of any of (1) to (4) above that is provided separately from the first control device, and a congestion control step of prioritizing one of the congestion control messages received from the first control device and the congestion control message received from the second control device.

[0012] (9) In one aspect of the present invention, a second control device is provided separately from a first control device that instructs an access network node (AN node) in a mobile communication system to start congestion control, and the second control device a RAN controller that controls the AN node, the RAN controller transmitting the AN node information to the RAN controller; The first control device Information to be transmitted to a core controller that controls the first control device, For congestion control Second information and and the second control device collects the No. 1 information and the second information. a determination step of determining whether the congestion control is necessary based on the above; and when the determination step determines that the congestion control is necessary, the second control device The RAN controller that collected the first information or and a transmitting step of transmitting a congestion control start message to the AN node to instruct the AN node to start congestion control. (10) One aspect of the present invention is the control method of (9) above, in which the AN node prioritizes a congestion control message received from the first control device and a congestion control message received from the second control device. (11) One aspect of the present invention is a control method according to either (9) or (10) above, in which the AN node changes the restriction probability for a signal that is the subject of the congestion control depending on the priority of the signal. Effect of the Invention

[0013] According to the present invention, it is possible to obtain the effect of enabling AN nodes to stably execute congestion control when the AMF falls into an overload state. [Brief description of the drawings]

[0014] [Figure 1] FIG. 1 is a block diagram showing an example of the configuration of a control system according to an embodiment. [Diagram 2] 10 is a sequence diagram illustrating an example of a procedure of a control method in a congestion control start stage according to an embodiment. FIG. [Diagram 3] 11 is a sequence diagram illustrating an example of a procedure of a control method in a congestion control end stage according to an embodiment. FIG. [Figure 4] FIG. 11 is a sequence diagram showing a modified example of the procedure of a control method in the congestion control start stage according to an embodiment. [Diagram 5] FIG. 2 is a block diagram showing an example of a device configuration of a control system according to an embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a block diagram showing an example of the configuration of a control system 1 according to an embodiment. In Fig. 1, the control system 1 performs control related to an AN node group 10 (AN node 11) and an AMF group 20 (AMF 21) of a 5G system.

[0016] The control system 1 includes an orchestrator 3, a Radio Access Network (RAN) controller 5, and a core controller 7. The RAN controller 5 performs control related to the AMF 21. The core controller 7 performs control related to the AMF 21. The orchestrator 3 manages and controls the RAN controller 5 and the core controller 7.

[0017] The operation of the control system 1 according to this embodiment will be described below.

[0018] [Congestion control start stage] A control method at the start of congestion control in the control system 1 shown in Fig. 1 will be described with reference to Fig. 2. Fig. 2 is a sequence diagram showing an example of the procedure of the control method at the start of congestion control according to this embodiment.

[0019] (Step S1) The RAN controller 5 (RAN Con.) collects information required for congestion control from the AN node 11. The core controller 7 (Core Con.) collects information required for congestion control from the AMF 21.

[0020] Examples of information required for congestion control include resource utilization rates (utilization rates of CPU (Central Processing Unit), memory, storage disk, NIC (Network Interface Card), etc.), traffic capacity, traffic volume for each signal type, signal delay, etc. Among these examples of information required for congestion control, information to be collected is set in advance in the RAN controller 5 and the core controller 7, respectively.

[0021] The information required for congestion control can be collected from logs and statistical information held within each of the AMF 21 and the AN node. Alternatively, the information required for congestion control can be collected from information generated from information held in the infrastructure (e.g., virtualization infrastructure) of each of the AMF 21 and the AN node.

[0022] For example, when the AMF 21 and the AN node 11 are constructed as CNFs (Cloud-native Network Functions) on a virtualization platform, by using a monitoring tool corresponding to the virtualization platform, information such as resource usage of the CNFs generated from information stored in the virtualization platform can be collected. Also, the traffic capacity of the CNF itself calculated from the amount of resources allocated to the CNFs on the virtualization platform can be collected. Also, information specific to the CNFs, such as the traffic volume for each signal type and signal delays, can be collected from logs and statistical information stored inside the CNFs.

[0023] (Step S2) The RAN controller 5 transmits the information necessary for congestion control collected from the AN node 11 to the orchestrator 3. The core controller 7 transmits the information necessary for congestion control collected from the AMF 21 to the orchestrator 3. The information necessary for congestion control may be transmitted to the orchestrator 3 periodically or when a specific event occurs.

[0024] The specific event is, for example, the core controller 7 detecting an abnormality in the information necessary for congestion control collected from the AMF. The orchestrator 3 that receives the information necessary for congestion control from the core controller 7 in which the abnormality detection has occurred may inquire the RAN controller 5 about the information necessary for congestion control, and may receive the information necessary for congestion control collected from the AN node 11 from the RAN controller 5.

[0025] (Step S3) The orchestrator 3 determines the necessity of congestion control in the AN node 11 based on the information necessary for congestion control received from the RAN controller 5 and the core controller 7, respectively. An example of a method for determining the necessity of congestion control in the AN node 11 is shown below.

[0026] (Example 1 of a method for determining the necessity of congestion control) If the resource usage rate of AMF21 exceeds a predetermined threshold, it is determined that congestion control is necessary in the AN node 11; on the other hand, if the resource usage rate of AMF21 does not exceed the predetermined threshold, it is determined that congestion control is not necessary in the AN node 11.

[0027] (Example 2 of a method for determining the necessity of congestion control) If the total traffic volume of signals addressed to AMF at AN node 11 exceeds the traffic capacity of AMF 21, it is determined that congestion control is necessary at AN node 11; on the other hand, if the total traffic volume does not exceed the traffic capacity of AMF 21, it is determined that congestion control is not necessary at AN node 11.

[0028] (Example 3 of a method for determining the necessity of congestion control) If delays or an increase in the response failure rate for response signals from the AMF 21 to the AN node 11 continue for a specified period or more in some or all network slices of the 5G system, it is determined that congestion control is necessary in the AN node 11; on the other hand, if delays or an increase in the response failure rate for the response signal do not continue for a specified period or more, it is determined that congestion control is not necessary in the AN node 11.

[0029] The above-mentioned examples 1, 2, and 3 of the method for determining the necessity of congestion control may be used alone or in combination.

[0030] If it is determined that congestion control is necessary in the AN node 11, the process proceeds to step S4. On the other hand, if it is determined that congestion control is not necessary in the AN node 11, the process in FIG.

[0031] (Step S4) The orchestrator 3 determines parameters to be used for congestion control in the AN node 11 based on the information required for congestion control received from the RAN controller 5 and the core controller 7, respectively. The parameters may include parameters determined by the AMF 21 in the NAS level congestion control. The parameters determined by the AMF 21 in the NAS level congestion control include, for example, the type of signal to be restricted, the probability of restricting the signal, a list of NSSAIs (Network Slice Selection Assistance Information) to be subjected to congestion control, and the probability of restricting the signal for each NSSAI.

[0032] The orchestrator 3 can obtain the traffic volume (number of signals) per unit time for each signal type in the AN node 11 by the RAN controller 5. The orchestrator 3 can also obtain the traffic capacity of the AMF 21 by the core controller 7. This allows the orchestrator 3 to calculate, for example, a value x that satisfies the following formula (1) as an appropriate value for the signal restriction probability.

[0033] "D×(1-x)≦C" (1) C is the traffic capacity (the number of signals that can be processed per unit time) of the AMF 21. D is the total number of signals per unit time transmitted from the AN node 11 to the AMF 21 when congestion control is not performed in the AN node 11. In addition, the orchestrator 3 determines the AN node 11 that will perform congestion control and the AMF 21 that will be the target of the congestion control (the AMF 21 that will be the destination of a signal that the AN node 11 will regulate by congestion control).

[0034] (Step S5) The orchestrator 3 transmits a congestion control instruction message to the RAN controller 5. The congestion control instruction message includes information such as the AN node 11 that performs the congestion control, the AMF 21 that is the target of the congestion control, and parameters used for the congestion control in the AN node 11.

[0035] (Step S6) Upon receiving the congestion control instruction message from the orchestrator 3, the RAN controller 5 transmits a congestion control start message to the AN node 11 that performs the congestion control indicated in the instruction message, instructing the AN node 11 to start congestion control. The congestion control start message includes information such as the AMF 21 that is the target of congestion control and parameters used for congestion control in the AN node 11.

[0036] (Step S7) When the AN node 11 receives the congestion control start message from the RAN controller 5, the AN node 11 sets the AMF 21 that is the target of congestion control indicated in the congestion control start message as the target of congestion control, and starts congestion control using the parameters used for congestion control included in the congestion control start message. This congestion control is the same operation as the congestion control executed by an AN node that receives a "NGAP OVERLOAD START" message specified in the 5G specifications from the AMF 21 that is the target of congestion control.

[0037] Note that, when the AN node 11 has already started congestion control (i.e., congestion control is being performed on the AMF 21), if the AN node 11 receives a new congestion control start message, the AN node 11 may follow the newly received congestion control start message. In this case, the AN node 11 may overwrite the parameters used for the congestion control that has already started with the parameters used for the congestion control included in the newly received congestion control start message.

[0038] [Congestion control end stage] A control method in the congestion control ending stage in the control system 1 shown in Fig. 1 will be described with reference to Fig. 3. Fig. 3 is a sequence diagram showing an example of the procedure of the control method in the congestion control ending stage according to this embodiment.

[0039] The AN node 11 is in a state of congestion control in which the AMF 21 is the target of congestion control.

[0040] (Step S21) The RAN controller 5 collects information necessary for congestion control from the AN node 11. The core controller 7 collects information necessary for congestion control from the AMF 21. The collection of the information necessary for congestion control is similar to step S1 in FIG. 2 described above.

[0041] (Step S22) The RAN controller 5 transmits the information necessary for congestion control collected from the AN node 11 to the orchestrator 3. The core controller 7 transmits the information necessary for congestion control collected from the AMF 21 to the orchestrator 3. The transmission of the information necessary for congestion control to the orchestrator 3 is similar to step S2 in FIG. 2 described above.

[0042] (Step S23) The orchestrator 3 determines the necessity of congestion control in the AN node 11 based on the information necessary for congestion control received from the RAN controller 5 and the core controller 7. The method of determining the necessity of congestion control is the same as that of step S3 in FIG. 2 described above.

[0043] If it is determined that congestion control is necessary in the AN node 11, the process proceeds to step S4. The process thereafter is the same as that after step S4 in Fig. 2. On the other hand, if it is determined that congestion control is not necessary in the AN node 11, the process proceeds to step S24.

[0044] (Step S24) The orchestrator 3 transmits an instruction message to end congestion control to the RAN controller 5. The instruction message to end congestion control includes information such as the AN node 11 that ends congestion control and the AMF 21 that is the target of congestion control termination.

[0045] (Step S25) Upon receiving the congestion control end instruction message from the orchestrator 3, the RAN controller 5 transmits a congestion control end message instructing the AN node 11 to end the congestion control indicated in the instruction message to end the congestion control. The congestion control end message includes information such as the AMF 21 that is the target of congestion control end.

[0046] (Step S26) When the AN node 11 receives the congestion control end message from the RAN controller 5, it ends the congestion control for the AMF 21 that is the target of congestion control end indicated in the congestion control end message. The end of the congestion control is the same operation as the congestion control executed by an AN node that receives an "NGAP OVERLOAD STOP" message defined in the 5G specifications from the AMF 21 that is the target of congestion control end.

[0047] [Modification of congestion control start stage] A modified example of the control method at the start of congestion control in the control system 1 shown in Fig. 1 will be described with reference to Fig. 4. Fig. 3 is a sequence diagram showing a modified example of the procedure of the control method at the start of congestion control according to this embodiment.

[0048] In this variant of the congestion control initiation phase, before the orchestrator 3 determines the need for congestion control in the AN node 11, it attempts to improve the overload state of the AMF 21 by expanding the resources of the AMF 21.

[0049] (Step S41) The RAN controller 5 collects information necessary for congestion control from the AN node 11. The core controller 7 collects information necessary for congestion control from the AMF 21. The collection of the information necessary for congestion control is similar to step S1 in FIG. 2 described above.

[0050] (Step S42) Based on the information necessary for congestion control collected from AMF 21(#1), the core controller 7 judges whether or not to expand the resources available to AMF 21(#1). In this judgment, the core controller 7 judges that AMF 21(#1) will expand the resources available to AMF 21(#1) when a predetermined condition indicating an overload state or a sign of an overload state of AMF 21(#1) is satisfied, and on the other hand, judges that AMF 21(#1) will not expand the resources available to AMF 21(#1) when the condition is not satisfied.

[0051] When the core controller 7 determines that the resources available to the AMF 21 should be expanded, the core controller 7 performs control to expand the resources available to the AMF 21. For example, the core controller 7 increases the resources allocated to the AMF 21 (#1) (scale-up). For example, the core controller 7 builds an additional AMF 21 (#2) (scale-out). Then, the process proceeds to step S43.

[0052] (Step S43) The RAN controller 5 collects information necessary for congestion control from the AN node 11. The core controller 7 collects information necessary for congestion control from the AMFs 21 (#1) and (#2). The collection of information necessary for congestion control is similar to that in step S1 of FIG. 2 described above.

[0053] (Step S44) The RAN controller 5 transmits the information necessary for congestion control collected from the AN node 11 to the orchestrator 3. The core controller 7 transmits the information necessary for congestion control collected from the AMFs 21 (#1) and (#2) to the orchestrator 3. The transmission of the information necessary for congestion control to the orchestrator 3 is similar to step S2 in FIG. 2 described above.

[0054] (Step S45) The orchestrator 3 determines the necessity of congestion control in the AN node 11 based on the information necessary for congestion control received from the RAN controller 5 and the core controller 7. The method of determining the necessity of congestion control is the same as that of step S3 in FIG. 2 described above.

[0055] If it is determined that congestion control is necessary in the AN node 11, the process proceeds to step S4. The process thereafter is the same as that after step S4 in Fig. 2. On the other hand, if it is determined that congestion control is not necessary in the AN node 11, the process in Fig. 4 ends.

[0056] The above is a description of each operation in the congestion control start stage, the congestion control end stage, and the modified example of the congestion control start stage of the control system 1 according to this embodiment.

[0057] In addition, the AN node 11 may receive messages related to congestion control from both the RAN controller 5 and the AMF 21. Specifically, the AN node 11 may receive a congestion control start message or a congestion control end message from the RAN controller 5, while receiving an “NGAP OVERLOAD START” message or an “NGAP OVERLOAD STOP” message from the AMF 21.

[0058] The AN node 11 prioritizes either the message regarding congestion control received from the RAN controller 5 or the message regarding congestion control received from the AMF 21.

[0059] For example, an on / off control of a RAN controller priority flag may be provided for the AN node 11. In this on / off control, the AN node 11 turns on the RAN controller priority flag when it receives a congestion control start message from the RAN controller 5, and turns off the RAN controller priority flag when it receives a congestion control end message from the RAN controller 5. When the RAN controller priority flag is on, the AN node 11 follows the message regarding congestion control received from the RAN controller 5.

[0060] For example, the AN node 11 may be set in advance to follow the message regarding congestion control received from the RAN controller 5 when the content of the message regarding congestion control received from the RAN controller 5 differs from the content of the message regarding congestion control received from the AMF 21. As a result, the AN node 11 follows the message regarding congestion control received from the RAN controller 5 when the content of the message regarding congestion control received from the RAN controller 5 differs from the content of the message regarding congestion control received from the AMF 21.

[0061] For example, the AN node 11 may be set in advance to follow the last received message regarding congestion control, so that the AN node 11 always follows the last received message regarding congestion control.

[0062] Furthermore, the AN node 11 may change the restriction probability for a signal that is the target of congestion control, depending on the priority of the signal.

[0063] In the 5G specification, the AN node 11 in a congestion control state with the AMF 21 as the target of congestion control restricts signals addressed to the AMF 21 that meet a predetermined restriction condition from being transmitted to the AMF 21 for the restriction probability if there is a restriction probability, and restricts all signals from being transmitted to the AMF 21 if there is no restriction probability. There are two types of restriction conditions (restriction conditions 1 and 2) as shown below (see Non-Patent Document 2, 8.7.7 "Operation Overview" and 9.2.6.14 "Message Configuration"). (Regulatory Condition 1) Restriction is applied to signals that match a certain type of signal (defined in the "Overload Action IE" in the "AMF Overload Response IE"), and the probability of this restriction is indicated in the "AMF Traffic Load Reduction Indication IE". (Regulatory Condition 2) Restriction condition 2 utilizes a slice identifier (S-NSSAI). Restriction is applied when all NSSAIs included in the request from the user equipment (UE) are included in the S-NSSAI list subject to congestion control (S-NSSAI list in the "Overload Start NSSAI List IE"). If a specific type of signal (defined in the "Overload Action IE" in the "Slice Overload Response IE") is indicated, restriction is applied to signals that match the specific type of signal. The restriction probability is indicated in the "Slice Traffic Load Reduction Indication IE". Note that an S-NSSAI is one slice identifier, and an NSSAI is a collection of S-NSSAIs.

[0064] Therefore, in the 5G specification, even if some of the restricted signals have a higher priority than other signals, they are all restricted with the same restriction probability. For this reason, it is preferable to change the restriction probability for the signal depending on the priority of the signal that is the target of congestion control. This makes it easier for signals with high priority to communicate among the restricted signals.

[0065] For example, the AN node 11 records the past traffic volume for each signal type, and determines the priority of each signal type based on this record. For example, the higher the traffic volume per unit time of a signal type, the higher the priority is set. The AN node 11 may control the restriction probability of each signal type so as to lower the restriction probability of a high-priority signal type and to raise the restriction probability of a low-priority signal type, while keeping the total restriction amount of restricted signals (total restriction amount unrelated to signal type) calculated based on the restriction probability of the signal unchanged.

[0066] Fig. 5 is a block diagram showing an example of a device configuration of a control system 1 according to this embodiment. The control system 1 shown in Fig. 5 includes an AMF 21 (first control device) and a second control device 50. The AMF 21 and the second control device 50 are connected to each other via a communication line. The AMF 21 and the second control device 50 are connected to the AN node 11 via a communication line. The second control device 50 is a control device corresponding to the RAN controller 5, the core controller 7, and the orchestrator 3 shown in Fig. 1 described above.

[0067] The second control device 50 is a control device provided separately from the AMF 21 (first control device) that instructs an access network node (AN node) 11 in a 5G system (mobile communication system) to start congestion control. The second control device 50 includes an information collection unit 51, a determination unit 52, a parameter determination unit 53, a transmission unit 54, and a resource extension control unit 55.

[0068] The information collecting unit 51 collects predetermined information for congestion control in the AN node 11 from the AN node 11 and the AMF 21. The determining unit 52 determines the necessity of congestion control in the AN node 11 based on the information collected by the information collecting unit 51. When the determining unit 52 determines that congestion control is necessary in the AN node 11, the transmitting unit 54 transmits a congestion control start message to the AN node 11 to command the start of congestion control.

[0069] The parameter determination unit 53 determines parameters to be used for congestion control in the AN node 11 based on the information collected by the information collection unit 51. When the determination unit 52 determines that congestion control is necessary in the AN node 11, the transmission unit 54 transmits a message to the AN node 11 notifying the AN node 11 of the parameters determined by the parameter determination unit 53.

[0070] When the determining unit 52 determines that congestion control is not necessary in the AN node 11, the transmitting unit 54 transmits to the AN node 11 a congestion control end message instructing the AN node 11 to end the congestion control.

[0071] The resource extension control unit 55 performs control to extend resources available to the AMF 21 based on the information collected by the information collecting unit 51. The determination unit 52 determines the necessity of congestion control in the AN node 11 based on the information collected by the information collecting unit 51 after the resources available to the AMF 21 are extended by the control of the resource extension control unit 55.

[0072] The AN node 11 is an access network node (AN node) in a 5G system (mobile communication system). The AN node 11 includes a receiving unit 111 and a congestion control unit 112.

[0073] The receiver 111 receives messages related to congestion control from both the AMF 21 (first control device) that instructs the AN node 11 to start congestion control, and a second control device 50 that is provided separately from the AMF 21. The congestion controller 112 prioritizes either the message related to congestion control received from the AMF 21 or the message related to congestion control received from the second control device 50. The congestion controller 112 changes the restriction probability for a signal that is a target of congestion control according to the priority of the signal.

[0074] According to this embodiment, by providing a second control device 50 (RAN controller 5, core controller 7 and orchestrator 3), it is possible to obtain the effect of enabling stable congestion control to be performed on the AN node 11 when the AMF 21 falls into an overload state.

[0075] Moreover, the second control device 50 (the RAN controller 5, the core controller 7, and the orchestrator 3) can acquire information required for calculating the barring probability of a signal in the AN node 11. This makes it possible to calculate an appropriate value of the barring probability of a signal in the AN node 11.

[0076] Furthermore, this will make it possible to improve the overall service quality of mobile communication systems such as 5G systems, thereby contributing to Goal 9 of the United Nations' Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0077] Although an embodiment of the present invention has been described in detail above with reference to the drawings, the specific configuration is not limited to this embodiment, and design changes and the like that do not deviate from the gist of the present invention are also included.

[0078] In addition, a computer program for implementing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the "computer system" referred to here may include hardware such as an OS and peripheral devices. In addition, the term "computer-readable recording medium" refers to writable non-volatile memory such as a flexible disk, an optical magnetic disk, a ROM, or a flash memory, a portable medium such as a DVD (Digital Versatile Disc), or a storage device such as a hard disk built into a computer system.

[0079] Furthermore, the term "computer-readable recording medium" includes devices that retain a program for a certain period of time, such as volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that serves as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line. The program may be transmitted from a computer system in which the program is stored in a storage device or the like to another computer system via a transmission medium, or by a transmission wave in the transmission medium. Here, the "transmission medium" that transmits the program refers to a medium that has a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. The program may be for implementing some of the functions described above, or may be a so-called differential file (differential program) that can implement the functions described above in combination with a program already recorded in the computer system. [Explanation of symbols]

[0080] 1...control system, 3...orchestrator, 5...RAN controller, 7...core controller, 10...AN node group, 11...AN node, 20...AMF group, 21...AMF, 51...information collection unit, 52...determination unit, 53...parameter determination unit, 54...transmission unit, 55...resource extension control unit, 111...reception unit, 112...congestion control unit

Claims

1. A second control device provided separately from a first control device that instructs an access network node (AN node) in a mobile communication system to start congestion control, an information collecting unit that collects first information for the congestion control, the first information being information transmitted from the AN node to a RAN controller that controls the AN node, and second information for the congestion control, the second information being information transmitted from the first control device to a core controller that controls the first control device; a determination unit that determines the necessity of the congestion control based on the first information and the second information collected by the information collection unit; a transmission unit that transmits a congestion control start message to the RAN controller or the AN node that has collected the first information when the determination unit determines that the congestion control is necessary, the congestion control start message instructing the RAN controller or the AN node that has collected the first information to start congestion control; A control device comprising:

2. A parameter determination unit that determines a parameter to be used in the congestion control based on the first information and the second information collected by the information collection unit, the transmission unit, when the determination unit determines that the congestion control is necessary, transmits a message to the AN node notifying the AN node of the parameters determined by the parameter determination unit. The control device according to claim 1 .

3. the transmission unit, when the determination unit determines that the congestion control is not necessary, transmits, to the AN node, a congestion control end message instructing the AN node to end the congestion control. The control device according to claim 1 or 2.

4. A resource expansion control unit performs control to expand resources available to the first control device based on the first information and the second information collected by the information collection unit, The determination unit determines the necessity of the congestion control based on the information collected by the information collection unit after the resources available to the first control device are expanded by the control of the resource expansion control unit. The control device according to any one of claims 1 to 3.

5. An access network node (AN node) in a mobile communication system, comprising: A receiving unit that receives messages related to congestion control from both a first control device that instructs an AN node to start congestion control and a control device (second control device) according to any one of claims 1 to 4 that is provided separately from the first control device; a congestion control unit that prioritizes one of a message regarding congestion control received from the first control device and a message regarding congestion control received from the second control device; An access network node comprising:

6. The congestion control unit changes a restriction probability for a signal according to a priority of the signal that is a target of the congestion control. An access network node as claimed in claim 5.

7. A computer of a second control device provided separately from a first control device that instructs an access network node (AN node) in a mobile communication system to start congestion control, an information collecting step of collecting first information for the congestion control, the first information being information transmitted from the AN node to a RAN controller that controls the AN node, and second information for the congestion control, the second information being information transmitted from the first control device to a core controller that controls the first control device; a determination step of determining the necessity of the congestion control based on the first information and the second information collected in the information collection step; a transmission step of transmitting a congestion control start message to the RAN controller or the AN node that collected the first information when the determination step determines that the congestion control is necessary, the congestion control start message instructing the RAN controller or the AN node that collected the first information to start congestion control; A computer program for executing the above.

8. A computer of an access network node (AN node) in a mobile communication system, a receiving step of receiving messages related to congestion control from both a first control device that instructs an AN node to start congestion control and a control device (second control device) according to any one of claims 1 to 4 that is provided separately from the first control device; a congestion control step of prioritizing a message regarding congestion control received from the first control device and a message regarding congestion control received from the second control device; A computer program for executing the above.

9. A second control device is provided separately from a first control device that instructs an access network node (AN node) in the mobile communication system to start congestion control; an information collecting step in which the second control device collects first information for the congestion control, the first information being information transmitted from the AN node to a RAN controller that controls the AN node, and second information for the congestion control, the second information being information transmitted from the first control device to a core controller that controls the first control device; a determination step in which the second control device determines the necessity of the congestion control based on the first information and the second information collected in the information collecting step; a transmission step of the second control device transmitting a congestion control start message to the RAN controller or the AN node that collected the first information, when the determination step determines that the congestion control is necessary, the congestion control start message instructing the start of congestion control; A control method comprising:

10. The AN node prioritizes one of a message regarding congestion control received from the first control device and a message regarding congestion control received from the second control device. The control method according to claim 9.

11. The AN node changes a restriction probability for a signal according to a priority of the signal that is a target of the congestion control. A control method according to any one of claims 9 and 10.

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