Network Node, Control Method, and Program for Reducing Power Consumption of Wireless Communication System

Abstract

To achieve power saving in a network without affecting communication of a terminal device.SOLUTION: A network node functioning as a session management function (SMF) determines, during a period when the amount of traffic between a plurality of terminal devices and a network decreases, that the number of terminal devices accommodated in a first UPF connected to an SMF among a plurality of user plane functions (UPFs) that accommodate the plurality of terminal devices is to be reduced, and controls a terminal device establishing a new session not to be accommodated in the first UPF, but to be accommodated in a second UPF which is different from the first UPF among the plurality of UPFs in response to determining that the number of terminal devices accommodated in the first UPF is to be reduced, and the first UPF is powered off in response to the number of terminal devices accommodated reaching zero.SELECTED DRAWING: Figure 7

Description

Technical Field

[0001] The present invention relates to power-saving technologies for wireless communication systems.

Background Art

[0002] In cellular communication systems, efforts have been made for many years to suppress the power consumption of terminal devices. In recent years, the importance of also suppressing the power consumption on the network side has been discussed. In a cellular communication system, when a terminal device is connected to the network, the terminal device is accommodated in one user plane function (UPF). Usually, a plurality of UPFs capable of accommodating a plurality of terminal devices respectively are prepared for the communication of a large number of terminal devices during network connection.

[0003] In a cellular communication system, for example, the traffic volume tends to decrease from late at night to early morning, and during that time, the number of connected terminal devices decreases. Therefore, it is expected that the power consumption in the network can be greatly reduced by turning off the power supply of the UPF that no longer accommodates the connected terminal devices (or setting it to a power-saving state).

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] While the UPF houses one or more terminal devices, it cannot turn off its power. To turn off the power of the UPF associated with a small number of terminal devices, for example, the UPF associated with those small number of terminal devices can be switched to another UPF (see Non-Patent Document 1). Thus, by associating the UPF with which the terminal device is associated from the first UPF to the second UPF and making the terminal devices associated with the first UPF non-existent, the power of the first UPF can be turned off. However, the method of Non-Patent Document 1 is a procedure for changing the UPF with which the terminal device in communication is associated, and such a change may affect the communication being executed by that terminal device.

Means for Solving the Problems

[0006] The present invention provides a method for realizing power saving of a network without affecting the communication of a terminal device.

[0007] A network node according to an aspect of the present invention is a network node functioning as a session management function (SMF), and in a time period when the traffic volume between a plurality of terminal devices and a network decreases, in a first user plane function (UPF) connected to the SMF among the plurality of user plane functions (UPF) that house the plurality of terminal devices, specifying means for specifying that the number of terminal devices to be housed should be reduced; and in response to the specification that the number of terminal devices to be housed in the first UPF should be reduced, controlling means for controlling a terminal device that newly establishes a session not to be housed in the first UPF but to be housed in a second UPF different from the first UPF among the plurality of UPFs. An acquisition means for acquiring information on a terminal device that has not communicated over a predetermined period from a base station device that houses the terminal device or a UPF that houses the terminal device; an instruction means for instructing the UPF that houses the terminal device to release a session of the terminal device that has not communicated over the predetermined period; a transmission means for transmitting a predetermined notification to a node that has a function of transmitting an instruction to the first UPF to turn off the power and that is a node for performing operation management and maintenance of a radio communication system including the network node, has su it.

Effects of the Invention

[0008] According to the present invention, it is possible to realize power saving of a network without affecting the communication of a terminal device.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential for the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and duplicate descriptions are omitted.

[0011] (System Configuration) Figures 1 and 2 show a configuration example of the wireless communication system according to this embodiment. This wireless communication system is, for example, a 5th generation (5G) cellular communication system of the 3rd Generation Partnership Project (3GPP (registered trademark)). Note that FIG. 1 shows a configuration example of the call processing system, and FIG. 2 shows a configuration example of the maintenance system. In this wireless communication system, as shown in FIG. 1, in the call processing system, the terminal device (UE) is connected to the core network via the base station device (gNB). The call processing system of this embodiment includes, for example, an access and mobility management function (AMF), a session management function (SMF), a user plane function (UPF), and a network data analytics function (NWDAF), similar to the conventional 5G core network. Further, as shown in FIG. 2, the maintenance system includes operation, administration, and maintenance (OAM) in addition to AMF, SMF, UPF, and NWDAF. Note that in FIGS. 1 and 2, only the core network functions related to this embodiment are shown for simplicity of explanation. That is, in FIGS. 1 and 2, illustration of other functions generally included in the core network is omitted, but in this embodiment as well, these other functions are naturally included in the core network. Each function of the core network is implemented by one or more network nodes. That is, one or more network nodes are configured to function as at least a part of a number of functions of the core network. In this embodiment, in the configurations in FIGS. 1 and 2, further, a UE type determination server is prepared. The function of this server will be described later.

[0012] The UE is a terminal device having a wireless communication function compliant with, for example, the 5G standard. The UE is connected to the core network via the gNB, and the AMF performs subscriber authentication and location management of the UE, and the SMF manages the communication session of the UE. The SMF determines the UPF to accommodate the UE and instructs the UPF to establish a session for the UE. The UE is connected to the data network (DN) via the gNB and the UPF, and uploads user data to other devices on the Internet, for example, or downloads user data from other devices.

[0013] Note that there are multiple UPFs, and the UE is accommodated in one of them. Here, in this embodiment, when the number of UEs accommodated in a UPF becomes zero (0), the power of the UPF is turned off (in one example, at least the power supply to the processor in the server implementing the UPF is stopped), thereby achieving power saving in the network. For example, statistically, there are time periods when the amount of communication traffic increases and time periods when it decreases. Here, in the time period when the amount of communication traffic decreases, since the number of UEs in the connected state decreases, the number of UEs accommodated in the UPF also decreases. Therefore, in such a time period, by turning off the power of the UPF that no longer accommodates UEs, the network can be power-saving. Note that when even one UPF is accommodating a UE, the power of that UPF cannot be turned off. Therefore, if the terminal devices connected to the network are distributed and accommodated in multiple UPFs, the power of none of the multiple UPFs can be turned off, and power saving cannot be achieved. On the other hand, 3GPP (registered trademark) has defined a method for switching the UPF in which the UE is accommodated. However, when switching the UPF in which the UE in communication is accommodated, there may be certain impacts such as the occurrence of a period during which the UE cannot communicate.

[0014] Therefore, in this embodiment, control is performed so that the UE is accommodated only in a part of the plurality of UPFs in such a form that such an influence does not occur, and by increasing the number of UPFs that do not accommodate the UE, efficient power saving of the network is achieved. Specifically, for example, OAM identifies the UPFs to be powered off from among the plurality of operating UPFs and notifies the SMF of the information indicating the identified UPFs. Then, the SMF causes the identified UPFs not to accommodate the UE. That is, the SMF causes other UPFs different from the identified UPFs to accommodate the UE newly connected to the network. According to this, the identified UPFs no longer accommodate the newly connected UE, and the number of UEs to be accommodated does not increase. Further, when the UE accommodated in the identified UPF becomes in a non-communication state, the identified UPF releases the session regarding the UE under the control of the SMF. As a result, the number of UEs accommodated in the UPF gradually decreases. Then, when the number of UEs accommodated in the identified UPF reaches zero, the SMF notifies the OAM that the number of UEs accommodated in the UPF has reached zero. In response to receiving this notification, the OAM instructs the UPF to turn off the power. In this way, by not allowing a specific UPF to accommodate the UE newly connected to the network, the number of UEs accommodated in the specific UPF can be gradually reduced. Then, by turning off the power of the UPF whose accommodation number has reached zero, the power consumption of the network can be reduced. Note that the OAM can dynamically change the number of UPFs to be powered off, for example, based on the prediction of the traffic volume. That is, the OAM estimates from the tendency of the past traffic volume fluctuations how much the traffic volume and the number of connected UEs will decrease from late at night to early morning, leaves the UPFs that can accommodate the UEs corresponding to the estimated value, and can turn off the power of the other UPFs.

[0015] In order to perform such processing more efficiently, in this embodiment, the UE type discrimination server can, for example, accommodate UEs having the same tendency in the same UPF based on the tendency of UE traffic.

[0016] For example, UEs are classified according to the probability of transitioning to the Idle state (CM (Connection Management)-Idle state) for each time period. For example, UEs can be classified into a type with a transition probability to the Idle state for each time period exceeding a predetermined value and a type with a transition probability less than or equal to the predetermined value. Also, using a plurality of thresholds, they may be classified into three or more types. According to this, one or more UEs of a type with a high probability of transitioning to the Idle state in a predetermined time period will be accommodated in the same UPF. As a result, it is expected that the number of UEs accommodated in that UPF will significantly decrease during that predetermined time period. Then, the OAM can greatly reduce the number of UEs accommodated in that UPF by preventing newly connected UEs from being newly accommodated in that UPF for that predetermined time period. As a result, the time until the number of UEs accommodated in that UPF reaches zero can be shortened, and the effect of suppressing power consumption can be improved. Also, by accommodating UEs with a low probability of transitioning to the Idle state in the same UPF, the operating rate of that UPF (the ratio of the number of actually accommodated UEs to the number of UEs that can be accommodated) can be increased, and it becomes possible to efficiently accommodate UEs by the UPF.

[0017] Note that the UE may be classified according to information other than, for example, the Idle transition probability for each time period, as its communication tendency. For example, information such as the amount of traffic transferred in one communication (from the start to the end of a session) or the communication duration from the start to the end of the communication may be used as the communication tendency of the UE. For example, for each time period, the UE can be classified into a UE with a traffic volume greater than a predetermined amount and a UE with a traffic volume less than or equal to the predetermined amount. That is, a UE with a large traffic volume has a tendency to be less likely to have its session disconnected and to continue to be accommodated in the UPF, while a UE with a small traffic volume has a tendency to be more likely to have its session disconnected and the period from when the UPF accommodates the UE until it releases the UE is short. Therefore, for example, in a certain time period, by causing a specific UPF to accommodate a UE that tends to have a small traffic volume in that time period, and not causing the UPF to accommodate a new UE, the number of UEs accommodated by the UPF can be made zero in a short period. Also, by accommodating UEs with a large traffic volume in the same UPF, the operating rate of the UPF can be increased, and the accommodation of UEs in the UPF can be made more efficient. Also, the UE can be classified into a type with a communication duration longer than a predetermined length and a type with a communication duration less than or equal to the predetermined length in a predetermined time period, and a UE with a short communication duration can be accommodated in a specific UPF. In this case, it is assumed that the session of the UE with the short communication duration will be released from the UPF within a short period. Therefore, by not causing the UPF to accommodate a new UE, the number of UEs accommodated by the UPF can be made zero in a short period. Also, by accommodating UEs with a long communication duration in the same UPF, the operating rate of the UPF can be increased, and the accommodation of UEs in the UPF can be made more efficient.

[0018] Furthermore, the tendency of the communication performed by the newly connected UE can be specified based on the characteristics of the UE or the information on the characteristics of the communication performed by the UE by the UE type discrimination server. For example, based on the characteristics of the UE such as the type of the UE, the network slice associated with the communication performed by the UE, the type of the data network of the communication partner with which the UE communicates, the location of the UE, the moving speed of the UE, etc., or the characteristics of the communication performed by the UE, the tendency of the communication performed by the UE can be specified.

[0019] For example, in the case of a UE being a smartphone and in the case of an IoT device, the time periods when traffic occurs and the tendencies of the amount of traffic transmitted and received in a single communication can vary greatly. For example, many smartphones are less likely to have communication occur during the time period from late at night to early morning, and there is a tendency for the traffic volume to increase at specific times during the day or within a certain period from evening. On the other hand, certain IoT devices may tend to generate a small amount of traffic at regular intervals. Thus, depending on the type of UE, the tendencies of the traffic volume for each time period and the transition probability to the Idle state can be specified. Note that smartphones and IoT devices are given as examples of the types of UEs, but more detailed types, such as classification based on the model information of the UE, may be specified. Also, the communication tendencies of the UE may be specified by a combination with other characteristic information. Also, the network slice corresponds to the communication service provided to the UE, and depending on the content of the communication service, the tendency of the generated traffic can be specified. Also, depending on the data network of the communication partner of the UE, what kind of communication is to be performed may be determined. In this case, if the data network of the communication partner of the UE can be identified, the tendency of the traffic generated in the communication performed by that UE can be identified. Also, depending on whether the location of the UE is a predetermined customer-attracting facility where a large amount of traffic occurs, such as an event venue, the tendency of the traffic can be specified. Furthermore, depending on the moving speed of the UE, when the UE is moving at a speed corresponding to a train or the like, a certain amount of traffic is generated during the movement, while when the UE is moving at a walking speed, a small amount of traffic is assumed to be generated, etc., and the tendency of the traffic can be specified by the moving speed. Note that these are examples of the characteristics of the UE or the characteristics of the communication performed by the UE, and information on other characteristics may also be used. Also, by combining the information on these characteristics, the communication tendencies of the UE may be specified in detail. Also, for each UE, historical information such as the traffic volume, communication time, and Idle transition probability in past communications may be collected, and the communication tendency for each UE may be specified.Further, based on information different from the characteristics of the UE and the characteristics of the communication performed by the UE, it may be specified what tendency the communication performed by the UE has. Note that the tendency of communication for each time period may be specified as a tendency obtained by dividing a day into time intervals of a predetermined length such as one-hour units, or for example, a tendency of communication considering weekdays, holidays, etc. may be specified.

[0020] The UE type discrimination server can collect information on what kind of communication each UE has performed in order to specify the tendency of communication of the UE such as the traffic volume, communication period, transition probability to the Idle state, etc. as described above. The UE type discrimination server collects communication information of each UE, for example, by making inquiries to the AMF, SMF, and NWDAF. For example, the UE type discrimination server transmits a request message to the AMF to request that a predetermined notification be sent when each UE transitions to the Idle state. The AMF transmits a predetermined notification to the UE type discrimination server when it detects that the UE being accommodated has entered the Idle state in accordance with this request message. Further, the UE type discrimination server transmits a request message to the SMF, for example, to request that a predetermined notification be sent when the communication session established for each UE is disconnected. The SMF transmits a predetermined notification to the UE type discrimination server when it detects that the communication session for the UE being accommodated has been disconnected in accordance with this request message. The UE type discrimination server can specify that the communication of each UE has ended in response to receiving a predetermined notification from the AMF or the SMF.

[0021] When the UE type discrimination server determines the end of this communication, in order to identify what kind of communication the ended communication was, it sends a request for obtaining analysis data to the NWDAF. The NWDAF has a function of collecting and analyzing data from each network function (NF) of the core network and OAM. The request for obtaining analysis data may include, for example, information specifying the type of data to be obtained and information specifying the UE for which the data to be obtained is to be performed. For example, the acquisition request indicates a request to acquire analysis information regarding the communication status of a specific UE, the movement state of a specific UE, or analysis information regarding a communication not related to a specific UE. The UE type discrimination server may, for example, as described above, specify a UE notified from the AMF or SMF that has transitioned to the Idle state or whose session has been disconnected, and request the NWDAF to provide information such as the communication status and movement state of that UE. At this time, a specific UE (or a group of specific UEs) may be specified by an identifier of the UE (for example, Subscription Permanent ID (SUPI)) and information indicating the group of the UE.

[0022] Note that, for example, information for limiting the data to be obtained, such as Single-Network Slice Selection Assistance Information (S-NSSAI) indicating a specific network slice, Data Network Name (DNN) indicating a specific data network, and application ID indicating a specific application, may be notified from the UE type discrimination server to the NWDAF. Also, information specifying the period for performing the analysis may be notified from the UE type discrimination server to the NWDAF. Note that these are just examples, and the request for obtaining analysis data may naturally include other information for enabling the acquisition of necessary analysis data.

[0023] NWDAF may specify the necessary data to the NFs (such as AMF, SMF, or UPF) that can provide the information required for the requested data analysis and request them to provide the data. For example, when information such as the start timing, end timing, and period of communication is required, NWDAF sends a request message to the NF that can provide the information on the start and end timing of the communication. Also, NWDAF may request information such as the uplink or downlink data rate (communication speed) and traffic volume from the NF that can provide such information. Further, NWDAF may request the information on the UE's location, either together with or instead of the above-mentioned information. Also, for example, information such as a timer for detecting the no-communication state, the UE's Connection Management state (e.g., CM-Connected or CM-Idle), and the UE's communication and access tendencies may be requested. Note that NWDAF may, for example, specify a specific UE or a group of specific UEs and request the above-mentioned information about that UE or group of UEs. These are just examples, and the requests from NWDAF to each NF may naturally include other information that can identify the data in order to obtain the data to be analyzed from each NF.

[0024] The NF that has received a request from NWDAF responds to the request and notifies NWDAF of the data to be analyzed. NWDAF can obtain information such as the start and end timing, period, duration, and traffic volume of the UE's communication through this notification. Also, NWDAF may obtain information on communication related to each application (such as start and end timing, duration, etc.). Note that NWDAF can also obtain information such as the ratio of the communication of a specific application among the communications performed within a specific period. Further, NWDAF can also obtain information related to the detection of the no-communication state for each session ID.

[0025] The NWDAF collects the data obtained in such a manner and analyzes the collected data. Then, it notifies the UE type discrimination server of the analysis result. Note that the above operations may be continuously and repeatedly executed, and the NWDAF may generate a new analysis result using the newly collected data and repeatedly notify the analysis result to the UE type discrimination server.

[0026] Through such procedures, the UE type discrimination server can identify, for the UEs notified by the AMF or SMF that have transitioned to the Idle state or whose sessions have been disconnected, the frequency of being in the Idle state for each time period and the traffic volume used for each time period. Thereby, the UE type discrimination server can identify the communication tendency of that UE. Also, the UE type discrimination server can perform such information collection for multiple communications of a large number of UEs and accumulate the information. Then, the UE type discrimination server can also identify the communication tendency for a group of UEs having common attributes, such as for each network slice, for each data network of the communication partner, for each location, etc. According to this, the UE type discrimination server can estimate the communication tendency based on the attributes, for example, for newly connected UEs.

[0027] The UE type discrimination server classifies each UE into a type according to communication tendencies (hereinafter referred to as "tendency types") depending on, for example, whether the transition probability to the Idle state is higher than a predetermined value and / or whether the traffic volume of the executed communication exceeds a predetermined amount. For example, a first tendency type in which the transition probability to the Idle state is higher than a predetermined value and the traffic volume exceeds a predetermined amount, a second tendency type in which the transition probability to the Idle state is equal to or lower than the predetermined value and the traffic volume exceeds a predetermined amount, a third tendency type in which the transition probability to the Idle state is higher than a predetermined value and the traffic volume is equal to or lower than a predetermined amount, and a fourth tendency type in which the transition probability to the Idle state is equal to or lower than the predetermined value and the traffic volume is equal to or lower than a predetermined amount. Each UE is classified into one of these types. Note that the classification of the tendency types of UE communication is performed for each time period. For example, regarding the communication tendency of a certain UE, it may be classified into the first tendency type in the first time period and the second tendency type in the second time period, etc., and the communication tendency of the UE may be classified into different tendency types for each time period. Note that the classification of the communication tendency of the UE may be associated with the position and moving speed of the UE, the network slice (S-NSSAI) corresponding to the communication executed by the UE, the data network (DNN) of the communication partner, the geographical range where the UE exists, etc. Also, the communication tendency of the UE may be associated with a combination of this information. For example, the communication tendency corresponding to the S-NSSAI indicating a network slice in which a large amount of data is continuously transmitted and received may be associated with the second tendency type described above, and the communication tendency corresponding to a network slice in which a small amount of data is repeatedly transmitted in a short cycle may be associated with the fourth tendency type described above. In this way, the values of S-NSSAI and DNN may be mapped to the communication tendency types.

[0028] The UE type discrimination server may, for example, identify the communication tendencies of a plurality of UEs and determine a threshold for classifying the communication tendencies of the UEs based on the identified information. Further, the threshold for classifying the communication tendencies of the UEs may be updated, for example, according to the result of how much the power consumption of the UPF can be reduced as a result of classifying the communication tendencies of the UEs. That is, for example, a predetermined value regarding the transition probability in the Idle state or a predetermined amount regarding the traffic volume used in classifying the communication tendencies of the UEs may be determined statistically or empirically.

[0029] After that, when the SMF establishes a communication session for a newly connected UE, the SMF requests the UE type discrimination server for information identifying the communication tendency type of the UE. For example, the SMF notifies the UE type discrimination server of information such as the UE's identification information, the DNN related to the UE's communication, and the S-NSSAI, and acquires information indicating the communication tendency type of the UE. Then, when the SMF identifies the communication tendency type of the UE based on the acquired information, the SMF selects the UPF that accommodates UEs with the same communication tendency as the UPF that accommodates the UE. As a result, each UPF may, for example, accommodate only UEs with similar communication tendencies. For example, the first UPF accommodates UEs that tend to continue communicating from late at night to early morning, the second UPF accommodates UEs that hardly communicate from late at night to early morning and tend to have a high transition probability to the Idle state, and the third UPF accommodates UEs that hardly communicate during the day and tend to have a high transition probability to the Idle state, so that the UEs are accommodated in the UPFs. Note that a UPF that accommodates UEs without being limited by the communication tendency may be prepared.

[0030] Note that the above-mentioned UE type discrimination server may communicate directly with the AMF, SMF, and NWDAF, or may communicate, for example, via a Network Exposure Function (NEF). That is, the UE type discrimination server may exist outside the core network and may be configured to communicate with the relevant NF within the core network via the NEF. Also, when selecting a UPF in which the UE is accommodated, a Network Repository Function (NRF) may be used. In this case, the NRF may include the UE type discrimination server. For example, the SMF obtains information on the UPF in which a newly connected UE should be accommodated from the NRF. At this time, the SMF may notify the NRF of, for example, the DNN or S-NSSAI associated with the communication of the UE, and may obtain information on the UPF appropriate for accommodating the UE from the NRF. Note that the SMF may notify the NRF of information indicating the communication tendency of the UE. In this case, the NRF can notify the SMF of a UPF suitable for accommodating the UE in consideration of the communication tendency.

[0031] (Device Configuration) FIG. 3 shows a configuration example of a device that implements each function in the above-described system according to this embodiment, such as an NF and a UE type discrimination server. This device is configured to include, in one example, a processor 301, a ROM 302, a RAM 303, a storage device 304, and a communication circuit 305. The processor 301 is a computer including one or more processing circuits such as a general-purpose CPU (Central Processing Unit) or an ASIC (Application Specific Integrated Circuit), and executes the overall processing of the device and the above-described respective processes by reading and executing programs stored in the ROM 302 and the storage device 304. The ROM 302 is a read-only memory that stores information such as programs and various parameters related to the processes executed by this device. The RAM 303 functions as a workspace when the processor 301 executes a program, and is a random access memory that stores temporary information. The storage device 304 is configured by, for example, a removable external storage device or the like. The communication circuit 305 is configured to include a connector and a processing circuit for communicating with other devices.

[0032] (Processing flow) An example of the processing flow executed in this embodiment will be described. Note that, hereinafter, the processing related to this embodiment will be described, and the normal processing defined in the standard in each NF will be omitted. The processing shown below can be realized by the processor 301 executing the programs stored in the ROM 302 and the storage device 304 in the device that implements each function. However, this is just an example, and dedicated hardware for implementing each function may be used instead.

[0033] FIG. 4 shows an example of the processing flow in which the UE type discrimination server collects information and identifies the communication tendency type of the UE. First, the UE type discrimination server requests the AMF to give a predetermined notification when the UE managed by the AMF transitions to the CM-Idle state (S401). The AMF sends a response to the request to the UE type discrimination server (S402) and monitors whether the UE has transitioned to the CM-Idle state. Also, the UE type discrimination server requests the SMF to give a predetermined notification when the session of the UE managed by the SMF is disconnected (S403). The SMF sends a response to the request to the UE type discrimination server (S404) and monitors whether the session of the UE has been disconnected. Thereafter, for example, the AMF detects that the UE has transitioned to the CM-Idle state (S405) and gives a predetermined notification to the UE type discrimination server in response to the detection (S406). In another example, the SMF detects that the session of the UE has been disconnected (S407) and gives a predetermined notification to the UE type discrimination server in response to the detection (S408). The UE type discrimination server sends a message requesting the NWDAF to analyze the communication of the UE when it receives a predetermined notification from at least one of the cases of receiving a predetermined notification from the AMF and receiving a predetermined notification from the SMF (S409).

[0034] The NWDAF transmits, for example, a message for requesting data necessary for analyzing the communication of the requested UE to the SMF (S410). When receiving this message, the SMF causes, for example, the UPF to report session information and obtains information necessary for analyzing the communication of the UE from the UPF (S411). Then, the SMF provides the obtained UPF information and the information necessary for analyzing the communication of the UE held by itself (SMF) to the NWDAF (S412). Also, the NWDAF transmits a message for requesting data necessary for analyzing the communication of the requested UE to the AMF as well (S413). Then, the AMF provides the information necessary for analyzing the communication of the UE held by itself (AMF) to the NWDAF (S414). Then, the NWDAF performs a predetermined analysis process based on the obtained information (S415) and notifies the UE type discrimination server of the analysis result (S416). The NWDAF can obtain, for example, the current state of the UE from the AMF / SMF and obtain information on the used traffic volume from the UPF. As an example, the NWDAF analyzes the communication of the UE including information on past communication, and can notify the UE type discrimination server of, for example, the frequency of transitioning to the Idle state for each time period and statistical information on the traffic volume transmitted and received in one communication as the analysis result. Note that, in the example of FIG. 4, an example is shown in which the UE type discrimination server communicates directly with the AMF, SMF, and NWDAF, but the UE type discrimination server may communicate with these NFs via, for example, the NEF. Also, the UE type discrimination server can collect information on all or some of the UEs that can be connected to the network, for example.

[0035] The UE type discrimination server identifies the communication tendency type of the UE based on the acquired information. For example, the UE type discrimination server grasps the Idle transition frequency for each time period of each UE and the amount of traffic transmitted and received based on the information from the NWDAF. Then, the UE type discrimination server determines the communication tendency type, for example, for each UE, by determining whether the Idle transition probability exceeds a predetermined value and whether the amount of traffic transmitted and received exceeds a predetermined amount for each time period. Note that the Idle transition probability can be identified, for example, as the number of Idle transitions within a predetermined time corresponding to the time width of the time period.

[0036] Examples of the communication tendency type are shown in FIG. 5. As shown in FIG. 5, for example, when the Idle transition probability exceeds a predetermined value, the Idle transition probability is set to "high", and when the Idle transition probability is less than or equal to the predetermined value, the Idle transition probability is set to "low". Also, for example, when the amount of traffic transmitted and received exceeds a predetermined amount, the amount of traffic is set to "high", and when the amount of traffic transmitted and received is less than or equal to the predetermined amount, the amount of traffic is set to "low". In this way, four types of communication tendency types can be prepared for each time period of the UE. Note that, for example, the communication tendency type of the UE may be classified based on only one of the Idle transition probability and the amount of traffic. Also, the communication tendency type is not limited to this, and the tendency type may be classified from other viewpoints. Note that the above-mentioned predetermined value and predetermined amount may be updated dynamically. Thereby, the UE can be classified into an appropriate communication tendency type according to the situation, and as will be described later, by accommodating the UE in an appropriate UPF, it becomes possible to use the UPF efficiently.

[0037] As described above, when the UE type discrimination server identifies the communication tendency type of a UE, it associates and stores the communication tendency type of the UE with the identification information of the UE (e.g., SUPI or IMSI (International Mobile Subscriber Identity)). Thereby, the UE type discrimination server can, for example, identify the tendency type specified from the past communications of a UE newly connected to the network based on the identification information of the UE. In the above example, the case of identifying the communication tendency type for each UE based on the analysis result of the communication of each UE has been described, but it is not limited to this. For example, the communication tendency type may be identified for each network slice. For example, the UE type discrimination server may request the NWDAF for the analysis result regarding a specific network slice. In this case, the NWDAF collectively analyzes the communications of a plurality of UEs using that network slice and notifies the UE type discrimination server of the analysis result. Based on this analysis result, the UE type discrimination server can identify the tendency type of what kind of communications will be performed when that network slice is used. Then, the UE type discrimination server can associate and store, for example, the identifier of the network slice (S-NSSAI) and the tendency type. Thereby, the UE type discrimination server can, for example, identify the communication tendency type of a UE newly connected to the network based on the network slice used in the communication of the UE. Similarly, for example, the analysis result for each destination data network is provided from the NWDAF to the UE type discrimination server, and the UE type discrimination server can identify the communication tendency type for each name of the data network (DNN). The UE type discrimination server associates and stores the DNN and the communication tendency type. Thereby, the UE type discrimination server can, for example, identify the communication tendency type of a UE newly connected to the network based on to which data network the UE connects. Also, the NWDAF can provide the UE type discrimination server with the analysis result of the communication, for example, for each location range where the UE exists.The UE type discrimination server can identify the communication tendency type for each location range where the UE exists based on this, and associate and store the location range and the tendency type. Then, the UE type discrimination server can identify the tendency type corresponding to the location where the UE exists as the communication tendency type of that UE.

[0038] Note that the UE type discrimination server may identify the communication tendency type for each case of combining, for example, the identification information of the UE, the S-NSSAI, the DNN, or the location information of the UE. That is, the communication tendency type when a specific UE communicates in a specific network slice, the communication tendency type when a specific UE communicates with a specific data network, the communication tendency type when a specific UE communicates while existing in a specific location range, etc. can be identified. Also, regardless of the identification information of the UE, the communication tendency type may be identified for combinations of the S-NSSAI, the DNN, and the location information of the UE. For example, the communication tendency type when a UE existing in a specific location range communicates in a specific network slice, the communication tendency type when a UE existing in a specific location range communicates with a specific data network, the communication tendency type when communication is performed using a specific network slice with a specific data network can be identified.

[0039] FIG. 6 shows an example of the processing flow when the SMF causes the UPF to accommodate a newly connected (newly establishing a session) UE. In this processing, when the AMF receives a session establishment request from the UE (S601), it sends a session establishment request for that UE to the SMF (S602). When the SMF receives the session establishment request, it sends a message to the UE type discrimination server to inquire about the type of that UE (S603). Here, the SMF includes the UE's identification information (SUPI or IMSI) in this message and sends it. The UE type discrimination server identifies the communication tendency type of the UE based on the UE's identification information in the received message. The communication tendency type of the UE can be identified based on past communications as described with reference to FIG. 5. Here, an example is shown where the UE type discrimination server identifies the communication tendency type of the UE using the UE's identification information. However, for example, the communication tendency type of the UE may be identified by the S-NSSAI, DNN, UE's location information, etc. That is, in the UE type discrimination server, when the communication tendency type corresponding to the S-NSSAI, DNN, UE's location information, etc. is identified, by providing the S-NSSAI indicating the network slice used in the UE's communication, the DNN of the UE's communication destination, and the UE's location information to the UE type discrimination server, the communication tendency type corresponding to those information can be identified as the communication tendency type of that UE. In this case, in S603, instead of or in addition to the UE's identification information, information such as the S-NSSAI indicating the network slice used in the UE's communication, the DNN of the UE's communication destination, and the UE's location information can be provided to the UE type discrimination server. The UE type discrimination server provides the SMF with the information on the communication tendency type stored corresponding to the provided information (UE's identification information, S-NSSAI, DNN, location information, etc.) (S604).

[0040] When the SMF obtains information on the tendency type of the UE's communication, it determines the UPF that accommodates that UE (S605). In one example, the SMF identifies the tendency type of the UE's communication from the obtained information for a predetermined time period (e.g., 15 minutes) after the current time. For example, if the current time is 0:55, the tendency type of the UE's communication is identified for the time period from 0:00 to 0:59 and the time period from 1:00 to 1:59. Note that the UE type discrimination server may be configured to provide only the information on the tendency type of the UE's communication for these time periods to the SMF in S604. For example, when a newly connected UE corresponds to tendency type 5 in FIG. 5, the SMF determines to accommodate that UE in the UPF that accommodates only the UEs of tendency type 5. Similarly, for the UEs of tendency type 8, the SMF determines to accommodate them in the UPF that accommodates only the UEs of tendency type 8. Note that, for example, for the newly connected UEs of tendency type 1 and tendency type 5, the SMF may accommodate them in the UPF that accommodates the UEs of tendency type 1, or may accommodate them in the UPF that accommodates the UEs of tendency type 5. Also, a UPF corresponding to the combination of tendency type 1 and tendency type 5 may be prepared and the UE may be accommodated in that UPF. Further, when the UPF restricts the accommodation of a newly connected UE to the UPF corresponding to the tendency type of the UE's communication, the UE may be accommodated in the UPF that accommodates the UEs of multiple tendency types.

[0041] Then, the SMF requests the determined UPF to establish a session for the newly connected UE (S606). The UPF sends a response to the SMF (S607). Note that in S606, the SMF notifies the UPF of the timer value used to detect the no-communication state for determining whether to disconnect the UE's session. The UPF will determine that the UE is in a non-communicating state when the period after the UE's communication stops reaches a predetermined period until this timer value expires. Note that the SMF manages the number of UEs accommodated in each UPF. The SMF increases the number of UEs accommodated in that UPF by 1 in response to the establishment of the session in this procedure. Thereafter, the UPF notifies the AMF of the session establishment (S608) and receives a response from the AMF (S609). Upon receiving this notification, the AMF notifies the UE that the session establishment has been accepted (S610). Note that the SMF notifies the OAM of the information indicating what type of trend UEs are accommodated in each UPF (S611). Thereby, the OAM can determine, for example, which UPFs to power on and which to power off for each time period.

[0042] In the above example, the case where the SMF determines the UPF in which the UE should be accommodated was shown. However, the selection of this UPF may be made by expanding the function of the NRF and having the NRF perform it. For example, the NRF can notify the SMF to be used in the communication related to the S-NSSAI and DNN by the AMF making an inquiry including the S-NSSAI and DNN related to the UE's communication. In the present embodiment, the SMF can notify the NRF of information on the tendency type of the UE's communication and inquire about an appropriate UPF. Note that the NRF can select a UPF suitable for the S-NSSAI and DNN related to the UE's communication and suitable for the tendency type of the UE's communication. In this case, in addition to the information on the tendency type of the UE's communication, the SMF can notify the NRF of information on the S-NSSAI and DNN related to the UE's communication and request the selection of an appropriate UPF. Also, in this case, although the SMF obtains the tendency type of the UE's communication from the UE type discrimination server and notifies the NRF of the tendency type, it is not limited to this. For example, the SMF may notify the NRF of information (such as the UE's identification information, S-NSSAI, DNN, location information, etc.) for inquiring about the tendency type of the UE's communication to the UE type discrimination server. In this case, the NRF can use the information notified from the SMF to make an inquiry to the UE type discrimination server and obtain information on the tendency type of the UE's communication from the UE type discrimination server. Also, the NRF may incorporate the UE type discrimination server. Then, based on the UE's identification information, S-NSSAI, DNN, location information, etc., the NRF can obtain the tendency type of the UE's communication by the incorporated UE type discrimination server. Based on the obtained information on the tendency type of the UE's communication, the NRF can select the UPF in which the UE should be accommodated and notify the result of the selection to the SMF. Thus, the SMF may select the UPF in which the UE should be accommodated, or a function other than the SMF may select the UPF.

[0043] Figure 7 shows an example of the process flow for reducing the number of UEs accommodated in a specific UPF. OAM determines to turn off the power of some UPFs, for example, during a time period when the number of connected UEs is decreasing (S701). For example, OAM determines to turn off the power of some UPFs for a time period when traffic is decreasing, such as late at night. At this time, OAM determines to turn off the power of only the UPFs that accommodate UEs that will no longer communicate (having at least one of the tendencies of a high Idle transition probability or a small traffic volume) during that time period. Note that when there are multiple UPFs that accommodate UEs regardless of the communication type, OAM can randomly select or select according to a predetermined rule a part of the multiple UPFs and determine to turn off the power of the selected UPFs. For example, OAM determines to maintain the power of a number of UPFs corresponding to the amount of UEs in communication predicted during that time period in the on state and turn off the power of the other UPFs.

[0044] When OAM determines the UPF for which the power is to be turned off, it sends a message instructing that the number of UEs accommodated in that UPF should be reduced to the SMF (S702). When the SMF normally receives the message, it sends a response to the OAM (S703). Thereafter, the SMF prevents newly connected UEs from being accommodated in the UPF specified by the message from the OAM (S704). For example, the SMF excludes the specified UPF from the candidate list of UPFs for accommodating UEs. As a result, that UPF will not be selected as the accommodation destination for UEs. For example, when OAM determines that the power of the UPF that accommodates only UEs of a predetermined tendency type should be turned off, even if a UE of the predetermined tendency type newly connects, the SMF causes the UE to be accommodated in another UPF different from that UPF. As a result, the number of UEs accommodated in the specified UPF will no longer increase further. Note that the SMF may determine to turn off the power of the UPF according to the time period. That is, the SMF may independently determine the UPF for which the power is to be turned off without an instruction from the OAM.

[0045] Thereafter, for example, in response to the gNB having confirmed the non-communication state of the connected UE, the gNB transmits a message requesting release of the UE context of that UE to the AMF (S705). Then, when the gNB receives a UE context release command from the AMF (S706), the gNB deletes the UE context of that UE. And the gNB transmits a message indicating that the release of the UE context has been completed to the AMF (S707). In this case, the AMF transmits a message requesting release of the PDU session to the SMF, specifying the UE whose UE context has been deleted at the gNB (S708). The SMF transmits a response message to this message to the AMF (S709). Thereby, the SMF can recognize the non-communication state of the specified UE. Note that this is one method for the SMF to identify the non-communication state of the UE, and the SMF may identify the non-communication state of the UE, for example, based on a report from the UPF. That is, as described in relation to S606 in FIG. 6, a timer for detecting the non-communication state can be set in the UPF. And when the timer started when the communication of the UE stops reaches the set value, the UPF notifies the SMF of a message for reporting that the UE is in the non-communication state (S710). And the SMF transmits a response message to this message to the SMF (S711). At this point, the SMF can recognize the non-communication state of the specified UE. Note that it is sufficient for the SMF to be able to identify the non-communication state by either one of the processes of S705 to S709 and the processes of S710 to S711.

[0046] When the SMF identifies that the UE is in a non-communicating state, it sends a message (S712) to the UPF that accommodates the UE, specifying the UE and requesting it to release the session. When the UPF receives the message, it releases the session of the specified UE and sends a response message to the SMF (S713). Then, the SMF notifies the AMF that the session of the UE has been released (S714) and receives a response message (S715). Thereafter, the AMF causes the gNB to release the PDU session resources established for the non-communicating UE (S716, S717). Also, the AMF causes the SMF to release the session (S718, S719). Thereby, the connection of the UE is disconnected. When this UE re-establishes the connection, if the UPF in which the UE was accommodated was excluded from the candidate list of accommodation destinations in S704, the SMF causes the UE to be accommodated by another UPF instead of that UPF. Thereby, the number of UEs accommodated in the UPF specified in S702 gradually decreases, and finally the number of accommodations becomes zero.

[0047] Next, an example of the process for controlling the power on / off of the UPF will be described with reference to FIG. 8. First, as described above, the SMF counts the number of UEs accommodated in each UPF. Then, the SMF identifies that the number of accommodated users has reached zero in the UPF specified in the above-mentioned S702 from the OAM, for example (S801). Here, an example is shown where the SMF counts the number of UEs accommodated in each UPF. However, instead of the SMF, the UPF may manage the number of UEs it is accommodating and send a predetermined notification to the SMF when the number becomes zero. In response to the number of UEs accommodated in the UPF reaching zero, the SMF sends a predetermined message to that UPF (S802), and by receiving a response message to the predetermined message from the UPF (S803), disconnects the connection with that UPF. Then, the SMF sends a message including information that can identify the UPF whose number of accommodated UEs has become zero to the OAM (S804). The OAM responds to this message (S805). Also, based on the message received in S804, the OAM identifies the UPF whose number of UEs has become zero and controls to turn off the power of that UPF (S806).

[0048] Thereafter, the OAM determines, for example, to start using the UPF that accommodates the UEs in the connected state or the UEs with an increasing traffic volume during the time period when the traffic volume increases (S807). Then, the OAM controls to turn on the power of the UPF to be used (S808), and notifies the SMF to specify that UPF and start accommodating UEs to that UPF (S809). The SMF sends a response to the notification (S810) and establishes a connection with the specified UPF (S811, S812). After establishing a connection with the specified UPF, the SMF adds that UPF to the candidate list of UE accommodation destinations (S813). As a result, the SMF can accommodate the UEs that newly request the establishment of a connection (session) thereafter to that UPF.

[0049] Note that for the UPF, the communication tendency type of the UE to be accommodated may be pre-assigned and the assignment may be fixed before and after power on / off. In this case, when the power of the UPF is turned on, since the tendency type to be accommodated in the UPF is determined, the SMF can accommodate the UE performing communication of that tendency type in that UPF. Further, the SMF may re-determine the communication tendency type of the UE to be accommodated in each UPF, for example, at the timing of power on / off of the UPF.

[0050] As described above, in this embodiment, by stopping the accommodation of the UE in a specific UPF, the number of UEs accommodated in that UPF can be set to zero. As a result, it becomes possible to turn off the power of the UPF without affecting the communication of the UE. Furthermore, by selecting the UPF to be accommodated for each communication tendency type of the UE, it is possible to efficiently accommodate the UE in other UPFs while reducing the number of UEs accommodated in some UPFs to zero in a short time. Therefore, it becomes possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote inclusive and sustainable industrialization and foster innovation."

[0051] The invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

Claims

1. A network node that functions as a Session Management Function (SMF), in a time period when the traffic volume between a plurality of terminal devices and a network decreases, in a first User Plane Function (UPF) connected to the SMF among the plurality of User Plane Functions (UPFs) that accommodate the plurality of terminal devices, identifying means for identifying that the number of terminal devices to be accommodated should be reduced; control means for controlling, in response to identifying that the number of terminal devices to be accommodated in the first UPF should be reduced, not to accommodate a terminal device that newly establishes a session in the first UPF, but to accommodate it in a second UPF different from the first UPF among the plurality of UPFs; acquiring means for acquiring information on a terminal device that has not communicated for a predetermined period from a base station device that accommodates the terminal device or a UPF that accommodates the terminal device; instructing means for instructing a UPF that accommodates a terminal device to release a session of the terminal device that has not communicated for the predetermined period; a node that performs operation management and maintenance of a radio communication system including the network node, and transmitting means for transmitting a predetermined notification to a node having a function of transmitting an instruction to turn off the power to the first UPF; A network node, characterized by comprising the above.

2. acquiring means for acquiring information indicating the communication tendency of a terminal device that newly establishes a session; selecting means for selecting a UPF in which the terminal device should be accommodated based on the communication tendency of the terminal device that newly establishes a session; further comprising, The control means controls so that the terminal device is accommodated in the UPF selected by the selecting means. The network node according to claim 1, characterized in that.

3. The communication tendency of the terminal device that newly establishes a session is determined based on at least one of the probability that the terminal device transitions to the IDLE state for each time period and the amount of traffic in the communication executed by the terminal device, The control means controls so that a plurality of terminal devices having the same tendency are accommodated in the same UPF. The network node according to claim 2, characterized in that.

4. Obtain information indicating the communication tendency of a terminal device that newly establishes a session, provide the obtained information to a device functioning as a network repository function, and further have an acquisition means for obtaining, from the device, information on the UPF in which the terminal device that newly establishes a session should be accommodated. The control means performs control so that the terminal device is accommodated in the UPF indicated by the information on the UPF. The network node according to claim 1, characterized in that.

5. Providing means for providing identification information of the terminal device that newly establishes a session to another device; Means for obtaining, from the other device, information indicating the communication tendency of the terminal device determined based on the communication that the terminal device that newly establishes a session has performed in the past; The network node according to any one of claims 2 to 4, further comprising:

6. Providing means for providing information on a network slice used in the communication of the terminal device that newly establishes a session to another device; Means for obtaining, from the other device, information indicating the communication tendency of the terminal device determined based on the communication that has been performed in the past using the network slice; The network node according to any one of claims 2 to 4, further comprising:

7. Providing means for providing information on the data network of the communication partner of the communication of the terminal device that newly establishes a session to another device; Means for obtaining, from the other device, information indicating the communication tendency of the terminal device determined based on the communication that has been performed in the past with the data network; The network node according to any one of claims 2 to 4, further comprising:

8. The network node further includes a notification means for notifying a node that performs operation management and maintenance of a radio communication system including the network node that a terminal device having the communication tendency is accommodated in the UPF in which the terminal device that newly establishes a session is accommodated. The network node according to any one of claims 2 to 4, characterized in that.

9. The specific means specifies that the number of terminal devices accommodated in the first UPF should be reduced by receiving, from the node performing the operation management and maintenance, a message instructing to specify the first UPF and reduce the number of accommodated users. The network node according to claim 8, characterized in that.

10. The first UPF is a UPF in which a terminal device having at least one of a tendency of a high idle transition probability or a small traffic volume in a time zone when the message is transmitted from the node performing the operation management and maintenance is accommodated. The network node according to claim 9, characterized in that.

11. Providing means for providing identification information of a terminal device that newly establishes a session to a device functioning as a network repository function (NRF); The NRF further has means for acquiring information on a UPF in which the terminal device should be accommodated, determined based on communication executed by the terminal device that newly establishes a session in the past. The control means performs control so that the terminal device is accommodated in the UPF indicated by the information on the UPF. The network node according to claim 1, characterized in that.

12. Providing means for providing information on a network slice used in communication of a terminal device that newly establishes a session to a device functioning as a network repository function (NRF); The NRF further has means for acquiring information on a UPF in which the terminal device should be accommodated, determined based on communication executed in the past using the network slice. The control means performs control so that the terminal device is accommodated in the UPF indicated by the information on the UPF. The network node according to claim 1, characterized in that.

13. Providing means for providing information on a data network of a communication partner of a terminal device that newly establishes a session to a device functioning as a network repository function (NRF); The NRF further has means for acquiring information on a UPF in which the terminal device should be accommodated, determined based on communication executed in the past with the data network. The control means performs control so that the terminal device is accommodated in the UPF indicated by the information on the UPF. The network node according to claim 1, characterized in that.

14. The network node according to claim 1, further comprising disconnecting means for disconnecting the connection with the first UPF in response to the number of terminal devices accommodated by the first UPF becoming zero.

15. The network node according to claim 12, further comprising determination means for determining that the number of terminal devices accommodated by the first UPF has become zero by counting the number of terminal devices accommodated by the first UPF or by receiving a notification from the first UPF that the number of terminal devices accommodated by the first UPF has become zero.

16. A control method executed by a network node functioning as a session management function (SMF), In a time period when the traffic volume between a plurality of terminal devices and a network decreases, specifying that the number of terminal devices to be accommodated should be reduced in a first user plane function (UPF) connected to the SMF among a plurality of user plane functions (UPFs) that accommodate the plurality of terminal devices; In response to the specification that the number of terminal devices to be accommodated in the first UPF should be reduced, controlling so that a terminal device establishing a new session is not accommodated in the first UPF but is accommodated in a second UPF different from the first UPF among the plurality of UPFs; Obtaining information on a terminal device that has not communicated for a predetermined period from a base station device that accommodates the terminal device or from a UPF that accommodates the terminal device; Instructing the UPF that accommodates the terminal device to release the session of the terminal device that has not communicated for the predetermined period; Sending a predetermined notification to a node having a function of sending an instruction to the first UPF to turn off the power, the node being a node for operation management and maintenance of a radio communication system including the network node; A control method characterized by including the above.

17. In a computer provided in a network node functioning as a session management function (SMF), In a time period when the traffic volume between a plurality of terminal devices and a network decreases, in a first User Plane Function (UPF) connected to the SMF among the plurality of UPFs that accommodate the plurality of terminal devices, it is specified that the number of terminal devices to be accommodated should be reduced. In response to the specification that the number of terminal devices to be accommodated in the first UPF should be reduced, a terminal device that newly establishes a session is not accommodated in the first UPF, and control is performed so that it is accommodated in a second UPF different from the first UPF among the plurality of UPFs. Information on a terminal device that has not communicated for a predetermined period is obtained from a base station device that accommodates the terminal device or a UPF that accommodates the terminal device. The UPF that accommodates the terminal device is instructed to release the session of the terminal device that has not communicated for the predetermined period. A node that performs operation management and maintenance of a radio communication system including the network node, and a predetermined notification is transmitted to the node having a function of transmitting an instruction to turn off the power to the first UPF. Program for.

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