Service control system, apparatus, and method

Abstract

The present invention makes it possible to suppress the occurrence of frequent server switching when a device receiving a service is moved. A server switching determination unit (101) determines to switch, to another server, the server that provides a service to a service-using terminal that receives the service from the server. When the server switching determination unit (101) determines to switch the server, a server determination unit (102) determines the server to be switched to from among a plurality of servers capable of providing the service to the service-using terminal, the server to be switched to being determined in consideration of an allowable delay satisfaction duration that indicates the length of time during which the service can be provided to the service-using terminal with a delay time within an allowable delay time.

Description

Technical Field

[0001] The present disclosure relates to a service control system, apparatus, and method.

Background Art

[0002] As a related art, Patent Document 1 discloses an edge computing system. The edge computing system has a plurality of edge host computer devices described in Patent Document 1. In the edge computing system, an edge host computer device that provides a specific service calculates a calculation delay time based on the situation of the calculation load. Further, the edge host computer device calculates a communication delay time required for communication between the terminal device that requests the specific service and the edge host computer device. The edge host computer device predicts the response delay time of the specific service based on the calculation delay time and the communication delay time.

[0003] When the predicted response delay time exceeds a predetermined delay time, the edge host computer device that provides the specific service inquires of another edge host computer device about the response delay time of the specific service. Another edge host computer device predicts the response delay time of the specific service in the same manner as above and transmits the predicted response delay time to the edge host computer device. The edge host computer device determines the edge host computer device that provides the specific service based on its own response delay time and the response delay time of another edge host computer device. Thereafter, the determined edge host computer device provides the specific service to the terminal device.

[0004] As another related technology, Patent Document 2 discloses a management device used in a MEC (Mobile / Multi-access Edge Computing) system. The MEC system is connected to at least one of a plurality of network elements constituting a mobile communication system and includes one or more physical resources arranged at a position physically close to at least one network element. In Patent Document 2, the management device manages a virtual environment constructed using at least one of the one or more physical resources.

[0005] The management device obtains, for a service usage terminal, a delay requirement indicating an allowable range regarding the delay of the mobile communication system. When access from the service usage terminal to the mobile communication system is detected, the management device identifies the base station to which the service usage terminal has accessed among the plurality of base stations included in the mobile communication system. The management device determines the physical resources to be used for constructing the virtual environment provided to the service usage terminal based on the identified base station and delay information indicating the delay between each of the one or more physical resources.

[0006] In determining the physical resources, the management server determines the physical resources to be used for constructing the virtual environment so as to satisfy the obtained delay requirement in consideration of the above delay. The management device determines, for example, the physical resources to be used for constructing the virtual environment based on the geographical location information of the base station specified as the network edge, that is, the base station to which the service usage terminal has accessed. In determining the physical resources, the physical resources closer to the network edge are preferentially selected.

Prior Art Documents

Patent Documents

[0007]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0008] However, in Patent Document 1, the movement of the terminal device is not considered for the switching of the server. In Patent Document 1, if the terminal device continues to move after the server is switched, the response delay time of the switched edge host computer exceeds the allowable delay time, and further switching of the edge host computer becomes necessary. For this reason, in Patent Document 1, the switching of the edge host computer may occur frequently. Frequent switching of the edge host computer may frequently cause service interruptions and disconnections associated with the switching process, leading to dissatisfaction among service users and unexpected accidents.

[0009] In Patent Document 2, in the construction of a virtual environment, the physical resource closest to the network edge is preferentially selected. When the service use terminal moves and the virtual environment is constructed, the physical resource closest to the network edge is considered to be the most suitable physical resource for service provision. However, in Patent Document 2, if the service use terminal continues to move after the virtual environment is constructed, the physical resource closest at the time of switching is not necessarily the most suitable physical resource. In Patent Document 2, if the service use terminal continues to move and the network edge changes, frequent reconstruction of the virtual environment may be required. Frequent reconstruction of the virtual environment may frequently cause service interruptions and disconnections associated with the reconstruction process, leading to dissatisfaction among service users and unexpected accidents.

[0010] In view of the above circumstances, one of the objectives of the present disclosure is to provide a service control system, device, and method capable of suppressing the occurrence of frequent server switching when the device receiving the service moves.

Means for Solving the Problems

[0011] To achieve the above object, the present disclosure provides, as a first aspect, a service control system. The service providing system includes a server switching determination unit that determines to switch a server that provides the service to a service using terminal that receives the service from the server, and when the server switching determination unit determines to switch the server, from among a plurality of servers that can provide the service to the service using terminal, considering an allowable delay satisfaction duration indicating a length of time during which the service can be provided to the service using terminal with a delay time within an allowable delay time, a server determination unit that determines a destination server.

[0012] The present disclosure provides, as a second aspect, a service control apparatus. The service providing apparatus includes a server switching determination unit that determines to switch a server that provides the service to a service using terminal that receives the service from the server, and when the server switching determination unit determines to switch the server, from among a plurality of servers that can provide the service to the service using terminal, considering an allowable delay satisfaction duration indicating a length of time during which the service can be provided to the service using terminal with a delay time within an allowable delay time, a server determination unit that determines a destination server.

[0013] The present disclosure provides, as a third aspect, a service control method. The service providing method includes determining to switch a server that provides the service to a service using terminal that receives the service from the server, and when it is determined to switch the server, from among a plurality of servers that can provide the service to the service using terminal, considering an allowable delay satisfaction duration indicating a length of time during which the service can be provided to the service using terminal with a delay time within an allowable delay time, determining a destination server.

Advantages of the Invention

[0014] The service control system, apparatus, and method according to the present disclosure can suppress the occurrence of frequent server switching even when the apparatus receiving the service moves.

Brief Description of the Drawings

[0015]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Modes for Carrying Out the Invention

[0016] Hereinafter, embodiments of the present disclosure will be described in detail with reference to the drawings. Note that the following description and drawings are appropriately omitted and simplified for clarity of explanation. Also, in the following drawings, the same elements and similar elements are denoted by the same reference numerals, and redundant explanations are omitted as necessary.

[0017] FIG. 1 shows a service control device according to a first embodiment of the present disclosure. The service control device 100 includes a server switching determination unit 101 and a server determination unit 102. The service control device 100 controls a server that provides a service to a service use terminal that receives service provision from the server. The service control device 100 is configured as a device including, for example, one or more processors and one or more memories. At least a part of the functions of each unit in the service control device 100 can be realized by the processor performing processing according to a program read from the memory.

[0018] FIG. 2 shows a service provision system including a server controlled by the service control device 100. The service provision system 200 includes a plurality of servers 210 and a service use terminal 220. In the service provision system 200, the plurality of servers 210 and the service use terminal 220 are interconnected via a network 250. The network 250 includes, for example, a wireless communication network using a communication line standard such as the fourth generation mobile communication system or LTE (Long Term Evolution). The network 250 may include a wireless communication network such as WiFi (registered trademark), the fifth generation mobile communication system (5G: 5th Generation), or local 5G.

[0019] Server 210 is a server that can provide services to service - using terminal 220. Service - using terminal 220 receives service provision from any one of a plurality of servers 210 via network 250. Service - using terminal 220 is configured as a device such as an in - vehicle communication device mounted on a moving body such as a vehicle, a car navigation system, or a display audio (DA). Alternatively, service - using terminal 220 may be a device such as a smartphone or a tablet owned by a user. Services provided to service - using terminal 220 include, for example, a danger alert service such as a collision, a traffic jam information distribution service, an approaching emergency vehicle notification service, and a dynamic map distribution service. Also, the above - mentioned services may be entertainment - based services such as a music distribution service and a video distribution service.

[0020] In the present embodiment, service control device 100 controls a server that provides services to service - using terminal 220 among a plurality of servers 210. Service control device 100 may be configured as a MEO (MEC Orchestrator) that manages a plurality of servers 210, for example, MEC servers. Service control device 100 may be connected to server 210 via network 250, or may be connected to server 210 via a network different from network 250.

[0021] Note that in this embodiment, the service control device 100 does not necessarily have to be physically configured as a single device. The service control device 100 may be configured by a plurality of devices interconnected via a network. For example, the server switching determination unit 101 and the server determination unit 102 may be configured as separate devices. In that case, the service control device 100 is also called a service control system. At least one of the server switching determination unit 101 and the server determination unit 102 may be arranged on the cloud. The server switching determination unit 101 and the server determination unit 102 may communicate via a network such as the Internet. Some or all of the functions of the service control device 100 may be included in any of the plurality of servers 210.

[0022] When a service is being provided to the service use terminal 220 from one server 210, the server switching determination unit 101 determines to switch the server that provides the service to the service use terminal 220. For example, the server switching determination unit 101 obtains, for example, the delay time between the service use terminal 220 and the server 210 that provides the service to the service use terminal 220. The delay time may be an actual measurement value or a predicted value. The server switching determination unit 101 determines whether to switch the server that provides the service to the service use terminal 220 based on the delay time. Alternatively, the server switching determination unit 101 may determine whether to switch the server that provides the service to the service use terminal 220 based on the location information of the service use terminal 220. For example, a predetermined area is set as a management area for each server. The server switching determination unit 101 may determine to switch the server when the location of the service use terminal 220 is outside or predicted to be outside the management area of the server 210 that is receiving the service.

[0023] When the server determination unit 102 determines that the server switching determination unit 101 has determined to switch the server that provides services to the service use terminal 220, the server determination unit 102 determines the destination server 210. The server determination unit 102 determines the destination server 210 in consideration of the allowable delay satisfaction duration from among a plurality of servers 210 that can provide services to the service use terminal 220. Here, the allowable delay satisfaction duration indicates the length of time during which services can be provided to the service use terminal 220 with a delay time within the allowable delay time.

[0024] Next, the operation procedure will be described. FIG. 3 shows the operation procedure (service control method) in the service control device 100. The server switching determination unit 101 determines whether to switch the server that provides services to the service use terminal 220 (step A1). When it is determined in step A1 that the server is to be switched, the server determination unit 102 determines the destination server 210 in consideration of the allowable delay satisfaction duration.

[0025] The server determination unit 102 switches the server that provides services to the service use terminal 220 to the destination server 210, for example, by controlling routing within the network 250. Alternatively, the server determination unit 102 may transmit the communication address information of the destination server 210 to the service use terminal 220 to cause the service use terminal 220 to switch the connected server.

[0026] In this embodiment, the service use terminal 220 may receive the provision of a plurality of services from one or more servers 210. In that case, the determination of whether to switch the server that provides the service to the service use terminal 220 may be made for each service use terminal 220 or for each service. For example, the server switching determination unit 101 may uniformly determine whether to switch the server that provides the service to the service use terminal 220 for a plurality of services received by the service use terminal 220. Alternatively, the server switching determination unit 101 may individually determine whether to switch the server that provides the service to the service use terminal 220 for each of the plurality of services received by the service use terminal 220.

[0027] Also, when the service use terminal 220 receives the provision of a plurality of services from one or more servers 210, the determination of the switching destination server may be made for each service use terminal 220 or for each service. For example, the server determination unit 102 may uniformly determine the switching destination server for a plurality of services received by the service use terminal 220. Alternatively, the server determination unit 102 may individually determine the switching destination server for each of the plurality of services received by the service use terminal 220.

[0028] Here, consider the case where, when the service use terminal 220 moves and switches the server, the switching destination server is switched only based on the delay time. In that case, it is considered that the server with the shortest signal transmission distance as seen from the service use terminal 220 is determined as the switching destination server. However, if the service use terminal 220 moves after the server that is the service provider is switched to the server with the shortest signal transmission distance, the switching destination server may not be able to immediately satisfy the allowable delay time, and a new server switch may occur immediately.

[0029] Thus, if server switching is performed based only on the delay time at the time of switching in server switching, the servers that can satisfy the allowable delay time may frequently change, and frequent server switching may occur. Frequent server switching may be accompanied by a temporary interruption or disconnection of application communication. Further, in server switching, it is necessary to transfer session information for continuing the application session from the server before switching to the server after switching, and as a result, the server load and the network load may increase.

[0030] In the present embodiment, the server determination unit 102 determines the server to be switched to in consideration of the allowable delay satisfaction duration. In the present embodiment, by considering how long the allowable delay time can be satisfied in determining the server to be switched to, the frequency of server switching can be suppressed, and frequent server switching can be suppressed. Since the present embodiment can suppress the frequency of server switching, the service can be stably provided to the service use terminal 220.

[0031] A second embodiment of the present disclosure will be described. FIG. 4 shows a service providing system including a service control device according to the second embodiment of the present disclosure. In the present embodiment, the service providing system 300 includes a service control device 310, a plurality of base stations (gNB: next Generation NodeB) 320, a plurality of servers 330, a server 335, a mobile body 340, and a 5GC (5th Generation Core network) 350. In the present embodiment, the service control device 310 corresponds to the service control device 100 described in the first embodiment shown in FIG. 1. The server 330 corresponds to the server 210 shown in FIG. 2.

[0032] The mobile body 340 is configured as a land vehicle such as, for example, an automobile, a motorcycle, a bus, a taxi, or a truck. Further, the mobile body 340 may be a railway vehicle, a ship, an aircraft, or a mobile robot such as an AGV (Automated Guided Vehicle). Furthermore, the mobile body 340 may be configured to be capable of autonomous driving based on information from sensors mounted on the mobile body. Also, the mobile body 340 may be a pedestrian.

[0033] The service use terminal 220 shown in FIG. 2 is mounted on the mobile body 340. Alternatively, a user who possesses the service use terminal 220 shown in FIG. 2 rides on the mobile body 340. Hereinafter, the provision of services to the service use terminal 220 mounted on the mobile body 340 and the provision of services to the service use terminal 220 possessed by the user riding on the mobile body 340 are also referred to as the provision of services to the mobile body 340. The present embodiment is an embodiment applied to a service provision system 200 in which the service control device 310 provides services to the mobile body 340.

[0034] The plurality of base stations 320 are each base stations in a 5G wireless communication network. Each base station 320 is connected to a 5GC 350, which is the core network of the fifth-generation mobile communication system, via a UPF (User Plane Function) 370. The 5GC 350 may be connected to an external network 360. The mobile body 340 (service use terminal 220) includes a communication device capable of 5G communication. The mobile body 340 connects to a base station 320 with which communication is possible among the plurality of base stations 320. The mobile body 340 is configured to be movable. When the mobile body 340 moves, the mobile body 340 may perform a handover process of switching the connection destination base station to a nearby base station 320. The base station 320 and the 5GC 350 correspond to network elements included in the network 250 shown in FIG. 2.

[0035] Each of the plurality of servers 330 and the server 335 constitutes a server system configured to be able to provide services to the mobile body 340. The server system may include a server (not shown in FIG. 4) disposed between the base station 320 and the 5GC 350. The plurality of servers 330 are respectively arranged corresponding to the base stations 320 and are connected to the base stations 320 via the UPF 370. Each server 330 is configured as, for example, an MEC server. The server 335 is a server connected to the 5GC 350.

[0036] FIG. 5 shows a configuration example of the server system. In the example shown in FIG. 5, the server system 400 is hierarchically divided into three layers from the first layer to the third layer. Assume that the first layer is the lowest layer and the third layer is the highest layer. The second layer is an intermediate layer between the first layer and the third layer. Note that FIG. 5 shows an example in which the server system 400 is hierarchically divided into three layers, but the number of layers is not limited to three. The server system 400 may be hierarchically divided into any two or more layers. Alternatively, the server system 400 may not be hierarchically divided into a plurality of layers.

[0037] The server system 400 includes one or more servers 410-1 in the first layer, one or more servers 410-2 in the second layer, and one or more servers 410-3 in the third layer. In the hierarchically divided server system 400, the servers are hierarchically divided, for example, according to the size of the management area. For example, assume that the management area of the servers 410-1 in the first layer, which is the lowest layer, is the smallest. The servers 410-1 in the first layer are servers whose management area is, for example, an area around one intersection. The management area of the servers 410-2 in the second layer is larger than the management area of the servers 410-1 in the first layer, which is the lower layer. The servers 410-2 in the second layer are servers whose management area is, for example, an area corresponding to one city. Also, the management area of the servers 410-3 in the third layer is larger than the management area of the servers 410-2 in the second layer. The servers 410-3 in the third layer are servers whose management area is, for example, an area corresponding to one prefecture.

[0038] In addition, in FIG. 4, the lines connecting the servers between the respective layers indicate the inclusion relationship of the administrative areas and do not necessarily represent the physical connection form. For example, assume that there is a server of the second layer connected to a server of the first layer with administrative area A and a second management server with administrative area B. When the administrative area of the server of the second layer is area C, area C includes area A and area B. Further, assume that there is a server of the third layer connected to a server of the second layer with administrative area C. When the administrative area of the server of the third layer is area D, area D includes area C.

[0039] The server 410-1 of the first layer shown in FIG. 5 corresponds to, for example, the server 330 (MEC server) shown in FIG. 4. The server 410-3 of the third layer corresponds to, for example, the server 335 shown in FIG. 4. The server 410-3 of the third layer may correspond to a server (not shown in FIG. 4) connected to the external network 360. The server 410-2 of the second layer may correspond to a server arranged between the base stations 320 and 5GC 350 not shown in FIG. 4. For example, the resource amount (such as processing capacity, memory capacity, and storage capacity) of the server 410-2 of the second layer is larger than the resource amount of the server 410-1 of the first layer. Also, the resource amount of the server 410-3 of the third layer is larger than the resource amount of the server 410-1 of the second layer.

[0040] FIG. 6 shows a configuration example of the service control device 310. The service control device 310 includes a switching determination unit 311, an evaluation unit 312, and a determination unit 313. The switching determination unit 311 corresponds to the server switching determination unit 101 shown in FIG. 1. The determination unit 313 corresponds to the server determination unit 102 shown in FIG. 1. The service control device 310 is connected to the 5GC 350 and can communicate with a plurality of servers 330 and 335 via the 5GC 350.

[0041] In this embodiment, the switching determination unit 311 determines whether to switch the server that provides services to the mobile body 340. For example, the switching determination unit 311 monitors the communication delay time with the mobile body 340 for the server that provides services to the mobile body 340. The switching determination unit 311 determines whether the delay time exceeds the allowable value, or whether it is predicted that the delay time will exceed the allowable value. When the switching determination unit 311 determines that the delay time exceeds the allowable value, or when it determines that it is predicted that the delay time will exceed the allowable value, it decides to switch the server that provides services to the mobile body 340.

[0042] Note that for the prediction of the delay time, various time series prediction methods such as a method using an autoregressive model and a method using deep learning can be used. Alternatively, the switching determination unit 311 may determine whether to switch the server that provides services to the mobile body 340 based on the position information of the mobile body 340. As an example, the switching determination unit 311 acquires the position information of the mobile body 340 from the mobile body 340 or another management device (not shown), etc., and when the mobile body 340 moves outside the management area of the server that provides services to the mobile body 340, it may determine whether to switch the server that provides services to the mobile body 340. As another example, the switching determination unit 311 acquires the handover event of the mobile body 340 from the mobile body 340 or the 5GC 350, and when the base station to which the mobile body 340 is connected is switched, it may determine whether to switch the server that provides services to the mobile body 340.

[0043] When the switching determination unit 311 decides to switch the server that provides services to the mobile body 340, the evaluation unit 312 selects a plurality of candidate servers (candidate servers) that are candidates for the switching destination from among the plurality of servers 330 and 335. For example, the evaluation unit 312 acquires information such as destination information, position information, speed information, and route information from the mobile body 340. For each of the candidate servers, the evaluation unit 312 evaluates the allowable delay satisfaction duration based on at least one of the destination point, moving speed, and moving route of the mobile body 340.

[0044] The evaluation unit 312 identifies, for example, for each point through which the mobile body 340 passes, the server closest to those points as candidate servers based on the route information of the mobile body 340. For each of the identified candidate servers, the evaluation unit 312 predicts the delay time related to the communication between the mobile body 340 and the candidate server when it is assumed that the mobile body 340 connects to each candidate server at the current point. Based on the predicted delay time of each candidate server, the evaluation unit 312 regards the candidate server farthest from the current location of the mobile body 340 among the candidate servers that satisfy the allowable delay time as the server that can satisfy the longest allowable delay time, and determines it as the switching destination server.

[0045] The evaluation unit 312 may, for example, predict the destination point or the movement route of the mobile body 340 from the destination information of the mobile body 340. The evaluation unit 312 may, for example, acquire the destination information from a car navigation system or a route guidance application. Alternatively, the evaluation unit 312 may, for example, predict the destination point or the movement route from the direction in which the road is heading when the road is a one-way road or when the road is a road on which many mobile bodies move straight without turning right or left.

[0046] The above delay time may include at least one of a communication delay time that depends on the signal transmission distance between the mobile body 340 and the server, and a processing delay time that depends on the processing load of each server. The evaluation unit 312 may predict the delay time (communication delay time) based on the signal transmission distance between the mobile body 340 and each candidate server. The signal transmission distance between the mobile body 340 and each candidate server may be estimated, for example, based on the distance between the position of the mobile body 340 and the base station 320 corresponding to each candidate server. Generally, the communication delay time of the server 330 corresponding to the base station 320 to which the mobile body 340 is connected is the shortest, and the communication delay time of another base station 320 (a base station to which the mobile body can be connected, different from the base station to which the mobile body is connected) or a server connected to the 5GC is considered to be longer than the communication delay time of the server 330 corresponding to the base station 320 to which the mobile body 340 is connected. Further, the evaluation unit 312 may predict the communication delay between the mobile body existing at the location and the server by using the measured value of the past communication delay between the server at the location.

[0047] The evaluation unit 312 may predict the processing delay time based on the processing load of each candidate server. The processing load of the server is, for example, the CPU (Central Processing Unit) usage rate, memory usage rate, number of running processes, and communication packet processing amount in the server. The evaluation unit 312 may obtain in advance the correspondence relationship between the processing load of the server and the processing delay time through measurement. The evaluation unit 312 may predict only one of the communication delay time and the processing delay time as the delay time, or may predict the sum of the communication delay time and the processing delay time as the delay time.

[0048] When it is assumed that the mobile body 340 moves along a predetermined movement route and continues to receive services from a specific one of the candidate servers, the evaluation unit 312 evaluates, as the allowable delay satisfaction duration, how long the delay time within the allowable delay time can be continuously achieved. The evaluation unit 312 evaluates the allowable delay satisfaction duration for each of the plurality of candidate servers. At this time, the evaluation unit 312 may predict the change in the connected base station accompanying the movement of the mobile body 340. For the prediction of the connected base station, the correspondence relationship between each location and the connected base station acquired in advance through measurement may be used. Also, for the prediction of the connected base station, the correspondence relationship between each location and the connected base station acquired in advance using analysis techniques such as radio wave propagation simulation may be used. Further, a correspondence relationship between each location and the connected base station may be generated by regarding the base station closest to each location as the connected base station at that location, and the correspondence relationship may be used for the prediction of the connected base station.

[0049] For example, the evaluation unit 312 may calculate the time during which the delay time is within the allowable delay time according to the moving speed of the mobile body 340. Generally, when the moving speed is high, it is considered that the time during which the mobile body 340 stays within the area of one base station 320 is short. Therefore, the continuous time during which the delay time becomes shorter than the allowable delay time is considered to be shorter than when the moving speed is low. The evaluation unit 312 evaluates the allowable delay satisfaction duration based on the time during which the delay time is within the allowable delay time.

[0050] In the present embodiment, the determination unit 313 determines the switching destination server from among the plurality of candidate servers for the switching destination based on the evaluation result of the allowable delay satisfaction duration. For example, the determination unit 313 may determine, as the switching destination server, a server having a sufficiently long allowable delay satisfaction duration. For example, any server may be determined as the switching destination server from among the servers having the longest allowable delay satisfaction duration or the servers whose allowable delay satisfaction duration exceeds a predetermined reference value.

[0051] In the evaluation unit 312, among a plurality of hierarchical servers, one of the plurality of hierarchies may be sequentially selected from the hierarchy side with a narrow management area, and at least a part of the servers in the selected hierarchy may be selected as candidate servers for the switching destination. The evaluation unit 312 evaluates the allowable delay satisfaction duration for each of the candidate servers and compares the allowable delay satisfaction duration with a first threshold value. When there is a candidate server whose allowable delay satisfaction duration is equal to or greater than the first threshold value, the evaluation unit 312 determines the switching destination server from among the candidate servers. When there is no candidate server whose allowable delay satisfaction duration is equal to or greater than the first threshold value, the evaluation unit 312 selects a hierarchy one level higher than the selected hierarchy, and re-evaluates the allowable delay satisfaction duration for the servers belonging to the one level higher hierarchy. Here, the first threshold value is, for example, the allowable delay satisfaction duration required as a minimum due to the characteristics of the service. The first threshold value may be the same value regardless of the service provided, or may be a different value for each service based on the characteristics of the service. Further, the first threshold value may be a different value according to the attributes of the mobile body. For example, the first threshold value for an emergency vehicle such as an ambulance may be set to a larger value than the first threshold value for a general vehicle.

[0052] Specifically, for example, in the server system shown in FIG. 5, the evaluation unit 312 first selects the first hierarchy, which is the lowest hierarchy, and selects, as a candidate server, the server 410-1 of the first hierarchy whose management area is, for example, the area near each intersection. The evaluation unit 312 evaluates the allowable delay satisfaction duration for the server 410-1. When there is a server 410-1 whose allowable delay satisfaction duration is equal to or greater than the first threshold value, the evaluation unit 312 may determine the server 410-1 whose allowable delay satisfaction duration is equal to or greater than the first threshold value as the switching destination server.

[0053] When there is no server 410-1 whose allowable delay satisfaction duration is equal to or greater than the first threshold, the evaluation unit 312 selects the upper second layer, and evaluates the allowable delay satisfaction duration for the server 410-2 of the second layer, for example, an area corresponding to each city as the management area. When there is a server 410-2 whose allowable delay satisfaction duration is equal to or greater than the first threshold, the evaluation unit 312 may determine the server 410-2 whose allowable delay satisfaction duration is equal to or greater than the first threshold as the switching destination server. When there is no server 410-2 whose allowable delay satisfaction duration is equal to or greater than the first threshold, the evaluation unit 312 selects the upper third layer, and evaluates the allowable delay satisfaction duration for the server 410-3 of the third layer, for example, an area corresponding to the whole prefecture as the management area. In this case, the determination unit 313 can search for a server whose allowable delay satisfaction duration is equal to or greater than the first threshold from the lower layer side.

[0054] The evaluation unit 312 may select servers of multiple layers as candidate servers and evaluate the allowable delay satisfaction duration. The evaluation unit 312 selects, for example, servers of multiple layers including the layer with the narrowest management area as candidate servers. The evaluation unit 312 evaluates the allowable delay satisfaction duration for each of the candidate servers. The evaluation unit 312 or the determination unit 313 compares the allowable delay satisfaction duration with a second threshold. Here, the second threshold is, for example, a time that satisfies the allowable delay satisfaction duration required as a minimum due to the characteristics of the service. The second threshold may be the same value as the first threshold or a different value.

[0055] The determination unit 313 determines the target server to be switched from among the candidate servers whose allowable delay satisfaction duration is equal to or greater than the second threshold. For example, the determination unit 313 may determine, as the target server to be switched, the server with the shortest allowable delay satisfaction duration among the candidate servers whose allowable delay satisfaction duration is equal to or greater than the second threshold. All of the candidate servers whose allowable delay satisfaction duration is equal to or greater than the second threshold satisfy the minimum required allowable delay satisfaction duration due to the service characteristics. Therefore, any of these servers can be said to be suitable as the target server to be switched. In this case, if the server with the longest allowable delay satisfaction duration is determined as the target server to be switched, it is considered that the upper-layer servers with a wider management area will continue to be selected. When the second threshold is set to a value greater than the first threshold and the target server to be switched is selected as described above, the determination unit 313 can preferentially determine the lower-layer server as the target server to be switched between the upper-layer server and the lower-layer server.

[0056] Next, the operation procedure in this embodiment will be described. FIG. 7 shows the operation procedure in the service control device 310. The switching determination unit 311 monitors the delay time of the server providing the service to the mobile body 340 (step B1). The switching determination unit 311 determines whether the delay time exceeds the allowable value (step B2). In step B2, the switching determination unit 311 may determine whether the delay time is predicted to exceed the allowable value. When the switching determination unit 311 determines in step B2 that the delay time exceeds the allowable value or the delay time is predicted to exceed the allowable value, it decides to switch the server that provides the service to the mobile body 340.

[0057] When the switching determination unit 311 determines to switch the server that provides services to the mobile body 340, the evaluation unit 312 selects a plurality of candidate servers (candidate servers) that are candidates for the switching destination from among the plurality of servers 330 and 335 (step B3). The evaluation unit 312 evaluates the allowable delay satisfaction duration for each of the candidate servers (step B4). In step B4, the evaluation unit 312 evaluates the allowable delay satisfaction duration based on, for example, at least one of the destination location, moving speed, and moving route of the mobile body 340. In step B4, the evaluation unit 312 may predict the delay time based on, for example, at least one of the processing load of the candidate server and the signal transmission distance between the mobile body 340 and the candidate server. The evaluation unit 312 evaluates the allowable delay satisfaction duration based on the time when the predicted delay time is within the allowable delay time.

[0058] Based on the allowable delay satisfaction duration evaluated in step B4, the determination unit 313 determines the switching destination server (step B5). After determining the switching destination server, the determination unit 313 may switch the server to which the mobile body 340 is connected to the server determined in step B5 by controlling the routing within the 5GC 350. Alternatively, the determination unit 313 may notify the mobile body 340 of the communication address information of the server determined in step B5. In that case, the mobile body 340 may connect to the server with the notified communication address information and receive service provision from the connected server. Note that the control of the routing within the 5GC 350 may be performed by issuing an instruction to the NEF (Network Exposure Function).

[0059] Figure 8 schematically shows an example of server switching. In the example shown in Figure 8, server 330A (Server A) is connected to base station 320A installed at location A via UPF 370A. Also, server 330B (Server B) is connected to base station 320B installed at location B via UPF 370B. UPFs 370A and 370B are nodes that play a role in processing user plane data in the 5G system. Assume that servers 330A and 330B are MEC servers. On the other hand, assume that server 335 connected to 5GC 350 is a higher-level server. Server 335 is also called a higher-level MEC server.

[0060] Assume that mobile unit 340 is receiving service from a server not shown in Figure 8. Switching determination unit 311 determines that the delay time has exceeded the allowable value and decides to switch the server that provides service to mobile unit 340. In the example shown in Figure 8, evaluation unit 312 predicts that mobile unit 340 will move through location A and toward location B. In that case, evaluation unit 312 selects, for example, servers 330A, 330B, and 335 as candidate servers.

[0061] Evaluation unit 312 calculates the delay time at each time when mobile unit 340 receives service from server 330A. Evaluation unit 312 also calculates, for each server, the delay time at each time when mobile unit 340 receives service from servers 330B and 335. The delay time can change over time. That is, the delay time can be expressed as a function of time. Evaluation unit 312 evaluates the allowable delay satisfaction duration when servers 330A, 330B, and 335 provide service to mobile unit 340 based on the calculated delay times.

[0062] The evaluation unit 312 compares the evaluation results of the allowable delay satisfaction durations of each server. Based on the evaluation results, the evaluation unit 312 determines the server that provides services to the mobile body 340. For example, when the moving speed of the mobile body 340 is relatively slow, it is considered that the mobile body 340 stays in the area of the base station 320A installed at point A for a long time. In that case, the determination unit 313 determines the server 330A as the server to be switched to. The mobile body 340 receives service from the server 330A, for example, by changing the routing within the 5GC 350.

[0063] As another case, consider the situation where a mobile body 340 with a relatively high moving speed leaves the area of the base station 320A and enters the area of the base station 320B installed at point B. In this case, when the allowable delay satisfaction duration of the server 330B is longer than the allowable delay satisfaction duration of the server 330A, the determination unit 313 can determine the server 330B as the server to be switched to. When the mobile body 340 moves towards point B, the time during which the mobile body 340 can receive service from the server 330B is considered to be longer than the time during which the mobile body 340 can receive service from the server 330A. In that case, by setting the server 330B instead of the server 330A as the server to be switched to, the frequency of server switching can be suppressed.

[0064] As yet another case, consider the situation where the moving speed of the mobile body 340 is even higher. In this case, when the allowable delay satisfaction durations of the servers 330A and 330B are relatively short and the allowable delay satisfaction duration of the server 335 that manages a wider area is relatively long, the determination unit 313 can determine the server 335 as the server to be switched to. When the moving speed is high, by setting the server 335, which is a higher-level server, instead of the MEC servers 330A and 330B as the server to be switched to, the frequency of server switching can be suppressed.

[0065] In this embodiment, the evaluation unit 312 evaluates the allowable delay satisfaction duration for candidate servers as the switching destination. The determination unit 313 determines the server as the switching destination in consideration of the evaluation result of the allowable delay satisfaction duration. By doing so, when the mobile body 340 moves, instead of an MEC server with a short signal transmission distance, a server with a long allowable delay satisfaction duration that can be stably connected can be set as the server as the switching destination. When switching the server that provides services to the mobile body 340, by setting an MEC server with a long allowable delay satisfaction duration as the server as the switching destination, the frequency of server switching associated with the movement of the mobile body 340 can be suppressed. In this embodiment, frequent server switching can be suppressed, and services can be stably provided to the mobile body 340.

[0066] In the above embodiment, an example in which the service control device determines the server as the switching destination when it is determined to switch the server that provides services to the service-using terminal has been described. However, the present disclosure is not limited to this. For example, the service control device may periodically evaluate the allowable delay satisfaction duration of each server, and when a server having an allowable delay satisfaction duration equal to or longer than a certain value is discovered, determine that server as the server as the switching destination. More specifically, regardless of whether it is determined to switch the server, the evaluation unit 312 periodically evaluates the allowable delay satisfaction duration for some servers. The determination unit 313 determines whether there is a server having an allowable delay satisfaction duration equal to or longer than a certain value based on the evaluation result in the evaluation unit 312. When there is a server having an allowable delay satisfaction duration equal to or longer than a certain value, the determination unit 313 may determine that server as the server as the switching destination.

[0067] In the present disclosure, the service control devices 100 and 310 can be configured using a computer device (server device). FIG. 9 shows a configuration example of the computer device that can be used for the service control devices 100 and 310. The computer device 500 includes a control unit (CPU) 510, a storage unit 520, a ROM (Read Only Memory) 530, a RAM (Random Access Memory) 540, a communication interface (IF: Interface) 550, and a user interface 560.

[0068] The communication interface 550 is an interface for connecting the computer device 500 to a communication network via wired communication means, wireless communication means, or the like. The user interface 560 includes a display unit such as a display, for example. Also, the user interface 560 includes an input unit such as a keyboard, a mouse, and a touch panel.

[0069] The storage unit 520 is an auxiliary storage device that can hold various data. The storage unit 520 does not necessarily have to be a part of the computer device 500, and may be an external storage device or a cloud storage connected to the computer device 500 via a network.

[0070] The ROM 530 is a non-volatile storage device. A semiconductor storage device such as a flash memory with relatively small capacity is used for the ROM 530, for example. The program executed by the CPU 510 can be stored in the storage unit 520 or the ROM 530. The storage unit 520 or the ROM 530 stores various programs for realizing the functions of each part of the service control device 100 or 310, for example.

[0071] The above program can be stored using various types of non-transitory computer-readable media and supplied to the computer device 500. Non-transitory computer-readable media include various types of tangible storage media. Examples of non-transitory computer-readable media include magnetic recording media such as flexible disks, magnetic tapes, or hard disks, magneto-optical recording media such as magneto-optical disks, optical disk media such as CDs (compact discs) or DVDs (digital versatile disks), and semiconductor memories such as mask ROMs, PROMs (programmable ROMs), EPROMs (erasable PROMs), flash ROMs, or RAMs. Also, the program may be supplied to the computer using various types of transitory computer-readable media. Examples of transitory computer-readable media include electrical signals, optical signals, and electromagnetic waves. The transitory computer-readable media can supply the program to the computer via wired communication paths such as electric wires and optical fibers, or wireless communication paths.

[0072] The RAM 540 is a volatile storage device. Various semiconductor memory devices such as DRAM (Dynamic Random Access Memory) or SRAM (Static Random Access Memory) are used for the RAM 540. The RAM 540 can be used as an internal buffer for temporarily storing data and the like. The CPU 510 expands and executes the program stored in the storage unit 520 or the ROM 530 in the RAM 540. By the CPU 510 executing the program, the functions of each part in the service control devices 100 and 310 can be realized. The CPU 510 may have an internal buffer that can temporarily store data and the like.

[0073] As described above, the embodiments of the present disclosure have been described in detail. However, the present disclosure is not limited to the above-described embodiments, and those obtained by making changes and modifications to the above embodiments without departing from the spirit of the present disclosure are also included in the present disclosure. For example, the above-described embodiments and the matters described in each embodiment can be combined as appropriate.

[0074] For example, some or all of the above embodiments may be described as follows, but are not limited thereto.

[0075] [Appendix 1] A server switching determination unit that determines to switch the server that provides the service to the service usage terminal that receives the service from the server, and When the server switching determination unit determines to switch the server, from among a plurality of servers that can provide the service to the service usage terminal, considering the allowable delay satisfaction duration indicating the length of time during which the service can be provided to the service usage terminal within the allowable delay time of the service usage terminal, a server determination unit that determines the destination server. A service control system comprising:

[0076] [Appendix 2] The service control system according to Appendix 1, wherein the server switching determination unit determines to switch the server that provides the service to the service usage terminal based on the delay time between the service usage terminal and the server that provides the service to the service usage terminal.

[0077] [Appendix 3] Each of the plurality of candidate destination servers further has an evaluation unit that evaluates the allowable delay satisfaction duration based on at least one of the destination location, moving speed, and moving route of the service usage terminal, The service control system according to Appendix 1 or 2, wherein the server determination unit determines the destination server from among the plurality of candidate destination servers based on the evaluation result of the allowable delay satisfaction duration.

[0078] [Appendix 4] Each of the plurality of servers includes one or more servers and is hierarchically divided into a plurality of hierarchies with different management area sizes, The evaluation unit sequentially selects one of the plurality of hierarchies from the hierarchy side with a narrow management area, evaluates the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchy as the candidate servers for the switching destination, and if there is a candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than a first threshold value, determines the switching destination server from among the candidate servers for the switching destination, and if there is no candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than the first threshold value, selects a hierarchy one level higher than the selected hierarchy, and evaluates the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchy as the candidate servers for the switching destination. The service control system according to Supplementary Note 3.

[0079] [Supplementary Note 5] The plurality of servers are each divided into a plurality of hierarchies including one or more servers, and the management areas have different widths from each other. The evaluation unit evaluates the allowable delay satisfaction duration with the servers in the plurality of hierarchies including the hierarchy with the narrowest management area as the candidate servers for the switching destination. The server determination unit determines the switching destination server from among the candidate servers for the switching destination whose allowable delay satisfaction duration is equal to or greater than a second threshold value. The service control system according to Supplementary Note 3.

[0080] [Supplementary Note 6] The evaluation unit predicts the delay time based on the processing load of the candidate servers for the switching destination and the signal transmission distance between the service use terminal and the candidate servers for the switching destination, and evaluates the allowable delay satisfaction duration based on the time during which the predicted delay time is within the allowable delay time. The service control system according to any one of Supplementary Notes 3 to 5.

[0081] [Supplementary Note 7] A server switching determination unit that determines to switch the server that provides the service to a service use terminal that receives the service from the server. When the server switching determination unit determines to switch the server, a server determination unit is provided that determines the destination server in consideration of the allowable delay satisfaction duration indicating the length of time during which the service can be provided to the service usage terminal within the allowable delay time for the service usage terminal, from among a plurality of servers capable of providing the service to the service usage terminal. A service control device.

[0082] [Appendix 8] The server switching determination unit determines to switch the server that provides the service to the service usage terminal based on the delay time between the service usage terminal and the server that provides the service to the service usage terminal. The service control device according to Appendix 7.

[0083] [Appendix 9] For each of the plurality of candidate destination servers, an evaluation unit is further provided that evaluates the allowable delay satisfaction duration based on at least one of the destination location, moving speed, and moving route of the service usage terminal. The server determination unit determines the destination server from among the plurality of candidate destination servers based on the evaluation result of the allowable delay satisfaction duration. The service control device according to Appendix 7 or 8.

[0084] [Appendix 10] Each of the plurality of servers includes one or more servers and is hierarchically divided into a plurality of hierarchies with different management area sizes. The evaluation unit sequentially selects one of the plurality of hierarchies from the hierarchy side with a narrow management area, evaluates the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchy as the candidate servers for the switching destination, and if there is a candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than a first threshold value, determines the switching destination server from among the candidate servers for the switching destination, and if there is no candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than the first threshold value, selects a hierarchy one level higher than the selected hierarchy, and evaluates the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchy as the candidate servers for the switching destination. The service control device according to Supplementary Note 9.

[0085] [Supplementary Note 11] The plurality of servers are each divided into a plurality of hierarchies including one or more servers, and the sizes of the management areas are different from each other. The evaluation unit evaluates the allowable delay satisfaction duration with the servers in a plurality of hierarchies including the hierarchy with the narrowest management area as the candidate servers for the switching destination. The server determination unit determines the switching destination server from among the candidate servers for the switching destination whose allowable delay satisfaction duration is equal to or greater than a second threshold value. The service control device according to Supplementary Note 9.

[0086] [Supplementary Note 12] The evaluation unit predicts the delay time based on the processing load of the candidate servers for the switching destination and the signal transmission distance between the service use terminal and the candidate servers for the switching destination, and evaluates the allowable delay satisfaction duration based on the time when the predicted delay time is within the allowable delay time. The service control device according to any one of Supplementary Notes 9 to 11.

[0087] [Supplementary Note 13] It is determined to switch the server that provides the service to the service use terminal that receives the service from the server. When it is determined to switch the server, among a plurality of servers capable of providing the service to the service use terminal, considering the allowable delay satisfaction duration indicating the length of time during which the service can be provided to the service use terminal with a delay time within the allowable delay time of the service use terminal, a service control method for determining the destination server to be switched.

[0088] [Appendix 14] Determining to switch the server includes determining to switch the server that provides the service to the service use terminal based on the delay time between the service use terminal and the server that provides the service to the service use terminal, according to the service control method described in Appendix 13.

[0089] [Appendix 15] Further including evaluating the allowable delay satisfaction duration for each of the plurality of candidate destination servers based on at least one of the destination location, moving speed, and moving route of the service use terminal. In the determination of the destination server, the destination server is determined from the plurality of candidate destination servers based on the evaluation result of the allowable delay satisfaction duration, according to the service control method described in Appendix 13 or 14.

[0090] [Appendix 16] Each of the plurality of servers includes one or more servers and is hierarchically divided into a plurality of hierarchies with different management area sizes. Evaluating the allowable delay satisfaction duration includes sequentially selecting one of the plurality of hierarchical levels from the hierarchical level with a narrower management area, evaluating the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchical level as candidate servers for the switching destination, and when there is a candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than a first threshold value, determining the switching destination server from among the candidate servers for the switching destination, and when there is no candidate server for the switching destination whose allowable delay satisfaction duration is equal to or greater than the first threshold value, selecting a hierarchical level one level higher than the selected hierarchical level, and evaluating the allowable delay satisfaction duration with at least a part of the servers in the selected hierarchical level as candidate servers for the switching destination, which is the service control method described in Supplementary Note 15.

[0091] [Supplementary Note 17] The plurality of servers each include one or more servers and are hierarchically divided into a plurality of hierarchical levels with different management area sizes. Evaluating the allowable delay satisfaction duration includes evaluating the allowable delay satisfaction duration with the servers in a plurality of hierarchical levels including the hierarchical level with the narrowest management area as candidate servers for the switching destination. In the determination of the switching destination server, the switching destination server is determined from among the candidate servers for the switching destination whose allowable delay satisfaction duration is equal to or greater than a second threshold value, which is the service control method described in Supplementary Note 15.

[0092] [Supplementary Note 18] Evaluating the allowable delay satisfaction duration includes predicting the delay time based on the processing load of the candidate servers for the switching destination and the signal transmission distance between the service use terminal and the candidate servers for the switching destination, and evaluating the allowable delay satisfaction duration based on the time during which the predicted delay time is within the allowable delay time, which is the service control method described in any one of Supplementary Notes 15 to 17.

Explanation of Reference Numerals

[0093] 100: Service control device 101: Server switching determination unit 102: Server determination unit 200: Service providing system 210: Server 220: Service using terminal 300: Service providing system 310: Service control device 320: Base station 330, 335: Servers 340: Mobile body 350: 5GC 360: External network 370: UPF 400: Server system 410: Server 500: Computer device 510: CPU 520: Memory unit 530: ROM 540: RAM 550: Communication interface 560: User interface

Claims

1. A server switching determination unit that determines to switch a server that provides the service to a service usage terminal that receives the service from the server; When the server switching determination unit determines to switch the server, from among a plurality of servers that can provide the service to the service usage terminal, considering the allowable delay satisfaction duration indicating the length of time during which the service can be provided to the service usage terminal within the allowable delay time, a service control system including a server determination unit that determines the destination server.

2. The server switching determination unit determines to switch the server that provides the service to the service usage terminal based on the delay time between the service usage terminal and the server that provides the service to the service usage terminal. The service control system according to Claim 1.

3. Further including an evaluation unit that evaluates the allowable delay satisfaction duration based on at least one of the destination location, moving speed, and moving route of the service usage terminal for each of the plurality of candidate destination servers; The server determination unit determines the destination server from among the plurality of candidate destination servers based on the evaluation result of the allowable delay satisfaction duration. The service control system according to Claim 1 or 2.

4. The plurality of servers each include one or more servers and are hierarchically divided into a plurality of hierarchies with different management area sizes; The evaluation unit sequentially selects one of the plurality of hierarchies from the side of the hierarchy with a narrow management area, evaluates the allowable delay satisfaction duration using at least a part of the servers in the selected hierarchy as candidate destination servers, and if there is a candidate destination server whose allowable delay satisfaction duration is equal to or greater than a first threshold, determines the destination server from among the candidate destination servers, and if there is no candidate destination server whose allowable delay satisfaction duration is equal to or greater than the first threshold, selects the next higher hierarchy of the selected hierarchy and evaluates the allowable delay satisfaction duration using at least a part of the servers in the selected hierarchy as candidate destination servers. The service control system according to Claim 3.

5. The plurality of servers each include one or more servers and are hierarchically divided into a plurality of hierarchies with different management area sizes; The evaluation unit evaluates the allowable delay satisfaction duration with the servers of a plurality of hierarchies including the hierarchy with the narrowest management area as candidate servers for the switching destination. The server determination unit determines the switching destination server from among the candidate servers for the switching destination whose allowable delay satisfaction duration is equal to or greater than a second threshold value. The service control system according to claim 3.

6. The evaluation unit predicts the delay time based on at least either the processing load of the candidate server for the switching destination or the signal transmission distance between the service use terminal and the candidate server for the switching destination, and based on the time within which the predicted delay time is within the allowable delay time, evaluates the allowable delay satisfaction duration. The service control system according to any one of claims 3 to 5.

7. A server switching determination unit that determines to switch the server that provides the service to a service use terminal that receives the service from the server, When the server switching determination unit determines to switch the server, considering the allowable delay satisfaction duration indicating the length of time for which the service can be provided to the service use terminal with a delay time within the allowable delay time from among a plurality of servers capable of providing the service to the service use terminal, a server determination unit that determines the switching destination server. A service control device comprising:

8. Determines to switch the server that provides the service to a service use terminal that receives the service from the server, When it is determined to switch the server, considering the allowable delay satisfaction duration indicating the length of time for which the service can be provided to the service use terminal with a delay time within the allowable delay time from among a plurality of servers capable of providing the service to the service use terminal, a service control method for determining the switching destination server.

9. Determining to switch the server includes determining to switch the server that provides the service to the service use terminal based on the delay time between the service use terminal and the server that provides the service to the service use terminal. The service control method according to claim 8.

10. For each of a plurality of servers that are candidates for the switching destination, further including evaluating the allowable delay satisfaction duration based on at least one of the destination point, moving speed, and moving route of the service usage terminal. The service control method according to claim 8 or 9, wherein, in determining the switching destination server, the switching destination server is determined from a plurality of servers that are candidates for the switching destination based on the evaluation result of the allowable delay satisfaction duration.

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