WO2023042519A1

WO2023042519A1 - Device, program, and control method for executing efficient load balancing control

Info

Publication number: WO2023042519A1
Application number: PCT/JP2022/025723
Authority: WO
Inventors: 忍難波; 晴久平山; 伸吾渡辺
Original assignee: Kddi株式会社
Priority date: 2021-09-14
Filing date: 2022-06-28
Publication date: 2023-03-23
Also published as: JP2023042318A

Abstract

In the present invention, a near-RT (real time) RIC (RAN intelligent controller) of an O-RAN (open-radio access network) provides, to an E2 node providing wireless communication to a terminal device in the O-RAN, information indicating that the required quality of first communication executed at the E2 node and/or newly received second communication should be changed.

Description

Control method, device, and program for executing efficient load distribution control

The present invention relates to load adjustment control technology in wireless communication.

The standardization of O-RAN (Open-RAN), which makes the radio access network (RAN) open/intelligent, is underway. In O-RAN, intelligent RAN is realized by controlling a plurality of E2 nodes connected to terminal devices by a RAN intelligent controller (RIC). Note that the RIC includes Near-RT RIC, which generally performs real-time (RT) control, and Non-RT RIC, which performs non-real-time control. The Non-RT RIC performs RAN analysis and policy management, etc., and the Near-RT RIC controls the E2 node according to the policy determined by the Non-RT RIC. Note that the control by the Near-RT RIC includes load distribution control between cells provided by the E2 node. This prevents traffic from concentrating on some E2 nodes and improves communication efficiency.

Even if load distribution control is performed, it is possible that the load cannot be sufficiently distributed between the E2 nodes. In that case, it is assumed that the communication quality at the congested E2 node will deteriorate.

The present invention provides efficient load regulation control technology.

A control method according to one aspect of the present invention is a control method executed by a Near-RT (Real Time) RIC (RAN Intelligent Controller) of an O-RAN (Open-Radio Access Network), wherein the terminal in the O-RAN Information indicating that an E2 node that provides wireless communication to a device should change the requested quality of at least one of the first communication being executed by the E2 node and the newly received second communication. including providing

A control method according to another aspect of the present invention is a control method executed by an E2 node that provides wireless communication to a terminal device in an O-RAN (Open-Radio Access Network), the Near-RT (Real Time) Acquiring from RIC (RAN Intelligent Controller) information indicating that the requested quality of at least one of the first communication being executed by the E2 node and the newly accepted second communication should be changed; and performing control to change requested quality of at least one of the first communication and the second communication based on the information.

According to the present invention, load adjustment control can be performed efficiently.

Other features and advantages of the present invention will become apparent from the following description with reference to the accompanying drawings. In the accompanying drawings, the same or similar configurations are given the same reference numerals.

The accompanying drawings, which are incorporated in and constitute a part of the specification, illustrate embodiments of the invention and, together with the description, serve to explain the principles of the invention.
FIG. 1 is a diagram illustrating a configuration example of a wireless communication system. FIG. 2 is a diagram showing a hardware configuration example of the device. FIG. 3 is a diagram showing a functional configuration example of the Non-RT RIC. FIG. 4 is a diagram showing a functional configuration example of the Near-RT RIC. FIG. 5 is a diagram illustrating a functional configuration example of an E2 node. FIG. 6 is a diagram illustrating an example of the flow of processing performed by Non-RT RIC. FIG. 7 is a diagram illustrating an example of the flow of processing performed by the Near-RT RIC. FIG. 8 is a diagram illustrating an example of the flow of processing performed by an E2 node.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the invention according to the claims, and not all combinations of features described in the embodiments are essential to the invention. Two or more of the features described in the embodiments may be combined arbitrarily. Also, the same or similar configurations are denoted by the same reference numerals, and redundant explanations are omitted.

(Configuration of wireless communication system)
FIG. 1 shows a configuration example of a wireless communication system according to this embodiment. The radio communication system of this embodiment is configured by adopting, for example, an O-RAN (Open-Radio Access Network) architecture. Note that FIG. 1 schematically shows only the Non-RT RIC 101, the Near-RT RIC 102, and the E2 node 103 as part of the functions of the O-RAN in order to simplify the explanation. The system may of course have all the functions specified for the general O-RAN architecture. Note that RT is an acronym for Real Time, and RIC is an acronym for RAN Intelligent Controller. The E2 node has the function of establishing a wireless connection with a terminal device and actually providing the wireless communication service to the terminal device. The Near-RT RIC is a control device that controls a plurality of E2 nodes, monitors the state of the RAN (E2 nodes) in short cycles of, for example, less than 1 second, and based on the monitoring results, the E2 nodes controls the behavior of The Non-RT RIC, for example, analyzes the state of the RAN at a long cycle of 1 second or more and determines the policy. An interface called an A1 interface is established between the Non-RT RIC and the Near-RT RIC, and control messages are transmitted and received between these elements via this A1 interface. An interface called an E2 interface is established between the Near-RT RIC and the E2 node, and control messages are transmitted and received between these elements via this E2 interface. Although not shown in FIG. 1, an O1 interface is established between the Non-RT RIC, the Near-RT RIC, and the E2 node, and control messages are transmitted between these elements via this O1 interface. Transmission and reception may occur.

In this embodiment, the load distribution control of the E2 node is performed in the configuration as shown in FIG. For example, the Non-RT RIC determines that load distribution control should be executed based on the congestion situation in the cell deployed by the E2 node. The Non-RT RIC then notifies the Near-RT RIC of information indicating that load distribution should be executed as policy information (A1 policy). When the Near-RT RIC receives the policy information, it monitors the load on the E2 node under its own control, and executes load distribution control as necessary. For example, when the Near-RT RIC determines that the load of an E2 node is greater than a predetermined value, it gives an instruction (E2 Policy/Control) to the relevant E2 nodes.

Note that the Non-RT RIC may notify the Near-RT RIC of the first policy information during non-congestion and the second policy information during congestion. In this case, the second policy information can be information indicating that the above-described load distribution should be performed. Note that the first policy information includes, for example, communication requirements (QoS) to be satisfied for each QoS (Quality of Service) flow in a network slice, and Near-RT RIC is configured to satisfy the QoS so that the UE connection control. The Near-RT RIC can then monitor the E2 node and perform load distribution control in response to a particular cell becoming congested.

In this way, based on the analysis of the long-term load by Non-RT RIC, it is determined that the load should be distributed roughly, and according to the decision, by Near-RT RIC, the load is adjusted according to the actual load situation. Decentralized control is provided. In this way, load distribution control is controlled by the Non-RT RIC and the Near-RT RIC that collectively control multiple E2 nodes that directly provide wireless connections to the UE, so that between multiple E2 nodes Higher level load distribution control can be performed as compared with direct load distribution.

On the other hand, if the Near-RT RIC monitors all communications in the controlled E2 node and performs load distribution control, the processing load for that control becomes excessive, resulting in deterioration of efficiency and accuracy of control. deterioration may occur. In this embodiment, in view of such circumstances, non-RT RIC notifies policy information that limits the control targets in Near-RT RIC.

For example, the Non-RT RIC can notify the Near-RT RIC that only a predetermined cell (E2 node) is subject to load distribution control. For example, the Non-RT RIC can notify the Near-RT RIC by including a list of identification information of cells to be processed (cell ID list) in policy information indicating that load distribution should be executed during congestion. That is, the Non-RT RIC stores the A1 policy in which information indicating that load distribution control should be performed during congestion and a list of cell identification information are stored in association with each other as the above-mentioned second policy information, and the Near-RT RIC provide to Then, the Near-RT RIC monitors the cell to be processed based on this information, and if the load exceeds a predetermined value, the UE connected to that cell is handed over to another cell to reduce the load. disperse Note that the Near-RT RIC may control the E2 node so that the handover is performed within the range of the cells listed in the policy information, or the listed cells The E2 node may be controlled such that a handover to a non-existent cell is performed. That is, the cells listed in the policy information may or may not include cells to which the load is to be offloaded. In this way, by limiting the cells targeted for load distribution, the Near-RT RIC can monitor the load only for the notified E2 node and execute load distribution control at that E2 node. can. Therefore, the Near-RT RIC does not need to monitor all the E2 nodes under its control, and can appropriately distribute the load with a low processing load.

In addition, the Non-RT RIC, for example, monitors each of the multiple E2 nodes on the O1 interface, and uses artificial intelligence (AI), for example, to determine the load within a predetermined period from the trend of traffic volume fluctuations. Detect areas where is expected to be high. Then, according to the detection results, the Non-RT RIC lists the E2 nodes corresponding to areas where the load is expected to be high, and the listed E2 nodes should be subject to load distribution control. Near-RT RIC can be notified. In addition, Non-RT RIC identifies congested areas for each day of the week and time period from the history of past traffic volume, and distributes the E2 nodes corresponding to the areas identified on that day of the week and time period for load distribution control. You may notify the Near-RT RIC of what should be covered. Also, when Non-RT RIC acquires advance information that a large number of UEs are expected to gather in a specific area, for example at a concert or sporting event, based on that advance information, the time and area to be congested identifiable. The Non-RT RIC may then notify the Near-RT RIC that the E2 node corresponding to the specified area at the specified time should be subject to load distribution control. It should be noted that such information that can specify the congestion time and area in advance may be obtained by directly inputting it to the Non-RT RIC from the network operator, etc., or may be obtained from the Non-RT RIC or other nodes may be acquired by searching via the Internet or the like. Also, a server may be prepared to accumulate such information, and the Non-RT RIC may acquire the information by periodically referring to the server.

Also, the target of load distribution control may be limited from a point of view other than the cell. For example, only a specific network slice may be subject to load distribution control. In this case, Near-RT RIC monitors the communication of UEs communicating in a specific network slice, and if the load due to that communication is concentrated in a specific cell, some or all of the UEs It can control the E2 node to handover to another cell. As an example, there may be network slices where it is assumed that the UE does not move or has a small amount of movement. In such a case, this network slice is not subject to load distribution control, and UEs that are unlikely to be subjected to handover are excluded in advance, thereby reducing processing loads such as monitoring for load distribution control. For example, the Non-RT RIC can notify the Near-RT RIC by including the identification information (slice ID) of the network slice to be processed in the policy information indicating that load distribution should be executed during congestion. In one example, the slice ID is S-NSSAI (Single-Network Slice Selection Assistance Information). That is, the Non-RT RIC stores the A1 policy in which the information indicating that load distribution control should be performed during congestion and the identification information of the network slice are associated and stored as the above-mentioned second policy information, and the Near-RT RIC provide to It should be noted that whether or not to be subject to load distribution control may be specified in units of QoS classes instead of in units of network slices. For example, instead of the identification information of the network slice, the identification information (QoS ID) of at least one of one or more QoS flows contained in the network slice is used to limit the UEs targeted for load distribution control. good too. The QoS ID is, for example, 5QI (5G QoS Indicator) or QCI (QoS Class Identifier). Also, one or more specific UEs may be specified to limit the target of load distribution control. For example, a list of identification information (UE IDs) for identifying UEs or identification information (group IDs) for identifying groups of UEs may be used to limit the UEs targeted for load distribution control. That is, the Near-RT RIC may be notified of an A1 policy that associates various identification information such as QoS ID, UE ID, and group ID with information for executing load distribution control during congestion.

In addition, when canceling the policy information related to load distribution control, the Non-RT RIC may send the policy information indicating that the load distribution control will not be performed to the Near-RT RIC, or it may request that the load distribution control be executed. policy information indicating that the previously provided policy information should be invalidated to the Near-RT RIC. Further, the policy information may be provided with an expiration date, and the policy information may be invalidated when the expiration date elapses.

Based on the policy information obtained from the Non-RT RIC, the Near-RT RIC monitors the communication of the E2 nodes subject to load distribution control and the UEs connected to the E2 nodes under control. Then, the Near-RT RIC has a predetermined value indicating the load of the cell designated as the target of load distribution control, the network slice subject to load distribution control, or the cell to which the UE performing communication of the QoS class belongs. If the value exceeds the value, it is determined to execute load distribution control. Also, the Near-RT RIC may determine to execute load balancing control, for example, when there is a network slice that cannot satisfy the SLA (Service Level Agreement) in the E2 node subject to load balancing control. . In addition, Near-RT RIC, through all E2 nodes, when there is a network slice that cannot satisfy the SLA in UE communication that is not specified as a target of load distribution control (that is, not subject to handover, etc.) , it may be determined to execute load distribution control.

When the Near-RT RIC determines to execute load distribution control, it controls the E2 node so that the UE communicating in the controlled cell is handed over to another cell. Note that handover in this embodiment may be handover to a cell in the same frequency band, or handover to a cell in a different frequency band. Near-RT RIC determines, for example, which UEs belonging to a congested cell should be moved to another cell. Near-RT RIC identifies, for example, the magnitude of load by each UE in a congested cell (for example, the number of physical resource blocks (PRB) used for communication of that UE), and based on the identification result , estimate the loads of the source and destination cells, respectively, when each UE hands over to another cell. Then, the Near-RT RIC determines, for example, which UE is handed over so that the respective loads in the handover source and handover destination cells do not exceed a predetermined value. select the target UE. The Near-RT RIC can then send an instruction to handover the UE selected as the target of handover to the E2 node to which the UE is connected and the E2 node to which the handover is to be made.

Note that the Near-RT RIC controls the E2 node by sending policy information and control information (E2 policy/control) to the E2 node. This policy information and control information is, for example, handover control for each UE, carrier aggregation (CA) for each UE secondary cell on / off, etc. Information for connecting the UE to a specific E2 node and communicating. can contain In addition, policy information and control information are, for example, parameters that serve as criteria for handover and cell reselection for each cell and each UE (for example, parameters for handing over a specific UE to a specific cell or for selecting a specific cell ) may be included. In addition, the Near-RT RIC must satisfy the required quality (SLA) for each network slice according to the A1 policy for non-congested (normal time) obtained from the Non-RT RIC when it is not congested. The E2 node is controlled by, for example, transmitting policy information or control information indicating to the E2 node.

Near-RT RIC can, for example, select UEs to perform handover based on the criteria that the loads in the handover source and handover destination cells do not exceed a predetermined value as described above, but is not limited to this. . Near-RT RIC, in addition to or instead of this, states that, for example, the SLA achievement rate of network slices in cells targeted for load distribution control (cells before and after handover) improves (at least does not deteriorate) after handover. Criteria may be used to select UEs for which handover is to be performed. In addition, Near-RT RIC uses a predetermined evaluation function such as a weighted addition value or a simple addition value of multiple SLA achievement rate values for multiple network slices, and the output value of the evaluation function improves ( UEs to perform handovers may be selected so as to at least not degrade). Note that the network slice to be evaluated here can be the network slice to be subjected to load distribution control. Also, the SLA achievement rate of the entire cell or network slice may be used to select a UE to perform handover, or the SLA achievement rate of a specific UE may be used instead. That is, UEs to be handed over may be selected so that the SLA achievement rate of a specific UE does not deteriorate (while allowing the SLA achievement rate of other UEs to deteriorate). Also, in these cases, UEs to be subjected to handover may be selected on the condition that communication quality such as throughput, error rate, delay amount, etc., is not degraded, rather than the SLA achievement rate. Also, a UE to be subjected to handover may be selected based on the quality required for each QoS flow and its sufficiency rate, or based on the output value of an evaluation function whose argument is a value such as a sufficiency rate.

In addition, Near-RT RIC identifies UEs that have poor radio quality in congested cells and that require a large amount of resources for communication as candidates for handover, and from among those UEs, the above-mentioned In this way, a UE can be selected that does not degrade indicators such as load, SLA achievement rate, and communication quality in a cell involved when handover is performed. Note that the Near-RT RIC may obtain feedback from the E2 node regarding the changes in the above-described indicators obtained as a result of this handover, and update the evaluation criteria. In one example, the weighting factors in the weighted summation value described above can be updated. Also, the evaluation function described above may be obtained by machine learning, and the evaluation function is updated based on the index value obtained as a result of the handover and the index value estimated in advance. may

The E2 node can notify the Near-RT RIC of information for determining the necessity of handover and the UE to be handed over as described above. For example, the E2 node has the number of PDU (Protocol Data Unit) sessions per cell, the number of UEs per cell, the amount of PDCP (Packet Data Convergence Protocol) traffic per cell, the PRB utilization rate per cell, the CCE (Control Channel Element) usage rate and other information to Near-RT RIC. For example, based on these information the load of the cell can be determined. In addition, the E2 node may notify the Near-RT RIC of detailed information on each of the above information for each network slice and each QoS class. For example, based on these pieces of information, the acceptability of handover for each cell can be specified. In one example, if there are a large number of low-priority network slice communications, it can be determined whether a network slice communication whose SLA is to be met can be accepted by reducing the communication quality for that communication. Note that these information may be notified from the E2 node to the Non-RT RIC via the O1 interface for long-term analysis. Also, the E2 node reports values such as throughput, packet delay, packet error rate average value, minimum value, and/or variance for each QoS class and slice to Non-RT RIC and Near-RT RIC. You may Based on this information, the SLA achievement rate for network slices can be calculated. Non-RT RIC and Near-RT RIC determine policies or control E2 nodes based on this information.

Furthermore, even if the Near-RT RIC executes load balancing control based on the policy information notified from the Non-RT RIC, the required quality of communication should be satisfied (for example, high-priority QoS flow communication, communication by a UE that has a predetermined contract), if the required quality cannot be met, for example, the communication quality of other communications can be reduced so that the specified communication can meet the required quality. . For example, a given communication may be allowed to meet its quality requirements by de-prioritizing the QoS of the QoS flows for which the quality requirements are not to be met. In one example, QoS flow communication for which the required quality should not be satisfied can be changed to best-effort communication in which communication speed and the like are not guaranteed. Note that this change may be made by the instruction of the Near-RT RIC, or may be executed independently by the E2 node. Also, at the time of this change, an inquiry may be made to the UE whose communication quality is scheduled to deteriorate as to whether or not to accept the deterioration of communication quality. Note that if the deterioration of communication quality is unacceptable, the Near-RT RIC or E2 node may disconnect the communication. It should be noted that, during the communication quality reduction control, while maintaining the network slice, the communication quality of at least a part of the QoS flows belonging to the network slice may be reduced, or the communication quality of the entire network slice may be reduced. may be lowered.

In addition, the Near-RT RIC or E2 node is not a predetermined communication from the UE in a situation where the predetermined communication cannot satisfy the required quality (for example, the predetermined network slice to be prioritized is not specified) When a request for communication is received, it may be accepted as communication of quality lower than that requested by the UE, such as best effort. In this case also, the UE that requested new communication is presented that it can be accepted if the communication does not satisfy the requested quality (that the requested communication quality is not guaranteed), and the communication is performed. You may inquire whether or not to do so. Then, if the Near-RT RIC or E2 node rejects communication that does not satisfy the requested quality from the UE, it can avoid executing that communication. Note that the best-effort communication in the above description is an example, and any network slice or QoS class that is assumed to be acceptable based on the load state of the E2 node, other than the predetermined communication that should satisfy the required quality. Communication can be controlled to take place.

It should be noted that the Near-RT RIC or E2 node, after executing the control to lower the required quality of communication, when the UE executing the predetermined communication moves to another location or when the communication ends, etc. Restores the lowered requested quality to the original level (if communication starts with lower quality than the requested quality, improves the quality to the requested quality) and re-changes the requested quality when there is a free space. you can go In this case, the UE may be notified that the communication quality is improved.

The process of changing and re-changing the requested quality includes, for example, information indicating that there is a change in QoS, and information indicating the network slice/QoS flow/UE to be changed in QoS and the QoS after change in association with each other. Including policy/control information sent from the Near-RT RIC to the E2 node. In one example, information can be included in the message indicating to change the QoS flow to another QoS class with lower priority. Also, in one example, information can be included in the message indicating that the network slice used for communication of a particular UE should be moved to another network slice (eg, best effort network slice). Furthermore, information indicating that the QoS class of the new QoS flow should be changed to a lower priority QoS class (to best effort type in some cases), and the network used for communication of the newly connected UE Information may be included indicating that the slice should be moved to another network slice (eg, a best effort network slice).

It should be noted that the non-RT RIC may change and re-change the required quality by transmitting policy information to the Near-RT RIC. For example, identification information specifying at least one of a network slice, QoS class, cell, UE, and QoS flow designates the target of change and re-change of the requested quality, and how to handle existing communication and new communication An A1 policy containing information indicating whether to do so may be provided to the Near-RT RIC. For example, whether new communications should be accepted with a prescribed quality requirement such as best effort or with a prescribed network slice with low required quality can be included in the A1 policy as information indicating how new communications should be handled. can be included. Similarly, changing the requested quality of existing communication to a predetermined requested quality such as best effort or transitioning to a predetermined network slice with lower requested quality determines how existing communication should be handled. It can be included in the A1 policy as information to indicate. The Near-RT RIC can generate policy information/control information according to this A1 policy and provide it to the E2 node. Based on the policy information/control information, the E2 node can change the requested quality of new communication or existing communication.

In addition, the E2 node has the traffic volume per UE QoS flow, the load per UE such as the number of PRBs used per UE, the traffic volume per network slice per cell and the load per network slice such as the number of PRBs used. , and, for each UE, information on received signal quality such as reference signal received power (RSRP), reference signal received quality (RSRQ), and CQI in the serving cell and neighboring cells is reported to Non-RT RIC and Near-RT RIC. sell. As a result, Non-RT RIC and Near-RT RIC can recognize the wireless communication environment for each UE and each network slice, and decide which UE/network slice to reduce the required communication quality. can do. In other words, Non-RT RIC and Near-RT RIC use this information to ensure quality in a given communication in which the required quality should be satisfied by lowering the required quality of which UE/which network slice. can be determined based on Non-RT RIC and Near-RT RIC, for example, reduce the load on the E2 node by not satisfying the required quality of communications by UEs associated with users who are allowed to reduce the communication quality by prior agreement. A communication with a large effect can be identified and the required quality of the communication can be lowered. In addition, Non-RT RIC and Near-RT RIC, for example, specify the magnitude of the load reduction effect when the required quality is reduced for communication of network slices and QoS flows with low priority, and A decision can be made to lower the required quality of communication. Note that Near-RT RIC repeatedly determines the UE and network slices/QoS flows that reduce the required quality until the communication quality for all predetermined communications that should satisfy the required quality can be satisfied. I can. In addition, Non-RT RIC and Near-RT RIC, for example, after satisfying the communication quality for all predetermined communication that should satisfy the required quality, any other UE or network slice / QoS flow can be determined based on the above information. In addition, the Near-RT RIC performs load distribution control for all predetermined communications that should meet the required quality, controls the reduction of required quality for ongoing communications, and controls the reduction of required quality when new communication requests are accepted. may be performed by the E2 node.

　The change and re-change control of the required quality may be performed independently of the load distribution control such as handover. That is, for example, when the required quality of a predetermined communication with a high priority is not satisfied, only the change and re-change control of the required quality are performed, and the load distribution control by handover or the like may not be performed. Also, the change and re-change processing of the required quality may be executed only for either existing communication or new communication. That is, maintain the required quality for existing communications and accept new communications with the required quality lowered, or lower the required quality for existing communications and accept new communications with the required quality. , and the like may be performed. Also, in the above description, it is explained that the requested quality is lowered, but at least part of the communication may be disconnected or rejected.

(Device configuration)
Next, configurations of the Non-RT RIC, the Near-RT RIC, and the E2 node will be described. These devices can be realized by general-purpose computers and servers with communication functions. Note that the Non-RT RIC, the Near-RT RIC, and the E2 node need only be logically separated, and two or more of them may be included in one device. These devices can be configured, for example, as communication devices having a hardware configuration as shown in FIG. The communication device, in one example, includes a processor 201 , a ROM 202 , a RAM 203 , a storage device 204 and a communication circuit 205 . The processor 201 is a computer including one or more processing circuits such as a general-purpose CPU (Central Processing Unit) and ASIC (Application Specific Integrated Circuit). By reading and executing the program stored in the device, the overall processing of the device and each of the above-described processings are executed. A ROM 202 is a read-only memory that stores information such as programs and various parameters related to processing executed by the apparatus. A RAM 203 is a random access memory that functions as a work space when the processor 501 executes programs and stores temporary information. The storage device 204 is configured by, for example, a detachable external storage device or the like. The communication circuit 205 includes, for example, a communication circuit for executing wireless communication or wired communication, and an antenna as necessary. For example, the communication circuitry 205 of the E2 node includes circuitry for wireless communication conforming to cellular communication standards. Non-RT RICs, Near-RT RICs and E2 nodes may also include communication circuitry 205 for communication between each other.

Fig. 3 shows an example of the functional configuration of Non-RT RIC. Non-RT RIC includes, for example, an A1 communication unit 301, an O1 communication unit 302, an information analysis unit 303, and a policy information setting unit 304 as its functions. The A1 communication unit 301 sets the A1 interface with the Near-RT RIC to perform communication. The O1 communication unit 302 sets the O1 interface between the E2 node and the Near-RT RIC to perform communication. The information analysis unit 303 acquires the above information from the E2 node, for example, estimates the cell load, the SLA achievement rate of the network slice, and whether the handover of the UE can be accepted, Perform various analyses, such as identifying cells that are likely to be congested.

The policy information setting unit 304 determines the policy to be set for the Near-RT RIC based on the result of the analysis by the information analysis unit 303, and sets the policy information indicating the policy as A1 policy to the A1 communication unit 301. Notify Near-RT RIC via. For example, when the policy information setting unit 304 determines from the analysis by the information analysis unit 303 that there is a network slice whose load is equal to or greater than a predetermined value and whose SLA achievement rate is equal to or less than a predetermined threshold, the policy information setting unit 304 targets the cell. Send A1 policy indicating that load distribution control should be executed to Near-RT RIC. In addition, the policy information setting unit 304 can also set policy information that notifies the quality requirements for each QoS flow for communication during non-congested times, and transmit it to the Near-RT RIC as A1 policy. That is, the policy information setting unit 304 can transmit, for example, A1 policy for quality control for each QoS flow during non-congestion and A1 policy for load balancing control during congestion to the Near-RT RIC.

For example, A1 policy during non-congestion includes a list of slice identification information and QoS IDs to which the policy information is applied, a list of cells, and a control target cell, network slice, and QoS class specified by those information. It contains information indicating the required quality such as guaranteed flow bit rate, packet delay amount, and packet error rate. On the other hand, the A1 policy during congestion includes information indicating that load distribution control should be performed, and information for specifying the control target (for example, slice identification information, QoS ID, cell list, or combinations thereof) are associated with and included. In addition, although load distribution control is described in this embodiment, the information indicating the control to be executed by the Near-RT RIC is replaced with the information indicating that the load distribution control should be executed. may be included in and notified to Near-RT RIC.

Fig. 4 shows an example of the functional configuration of Near-RT RIC. The Near-RT RIC includes, for example, an A1 communication unit 401, an E2 communication unit 402, an O1 communication unit 403, a policy information acquisition unit 404, and a load distribution control unit 405 as its functions. The A1 communication unit 401 sets the A1 interface with the Non-RT RIC to perform communication. The E2 communication unit 402 sets an E2 interface and performs communication with the E2 node. The O1 communication unit 403 sets the O1 interface with the Non-RT RIC to perform communication. The policy information acquisition unit 404 acquires policy information (A1 policy) from the Non-RT RIC.

The load distribution control unit 405 acquires load identifiable information from a large number of E2 nodes under its control via the E2 communication unit 402, and determines whether load distribution control should be executed based on the information. do. For example, the load distribution control unit 405 determines that load distribution control should be executed when the load in a cell or network slice/QoS class designated as a target for load distribution control by the A1 policy exceeds a predetermined threshold. I can. Note that the load distribution control unit 405, for example, collects information and calculates load values for cells and network slices/QoS classes that are not specified as targets for which load distribution control should be performed by the A1 policy. You don't have to. It should be noted that even in such non-target cells and network slices/QoS classes, the E2 node that provides the communication can execute load balancing control with surrounding E2 nodes. As a result, load distribution can be performed locally. On the other hand, with the Near-RT RIC executing this load distribution control, it is possible to perform load distribution control that considers a wide range of E2 nodes compared to the case where E2 nodes locally execute load distribution control. Therefore, more efficient load distribution can be performed. When the load distribution control unit 405 determines that load distribution control is necessary in the target cell or network slice/QoS class of load distribution control, as described above, which UE is to be handed over to which cell. Make a decision and notify the E2 node of the outcome of that decision. Note that this notification is transmitted to the E2 node by the E2 communication unit 402 via the E2 interface as policy information or control information.

As an option, the load distribution control unit 405, if the communication quality to be satisfied is not obtained even if the load distribution control is executed (when the SLA achievement rate is insufficient in each network slice), some networks Control can be performed to reduce the communication quality of the slice/QoS flow communication. For example, the load distribution control unit 405 can control the E2 nodes to communicate with QoS with lower quality requirements for QoS flows included in a certain network slice. Also, the load distribution control unit 405 can control the E2 node to perform a new communication request at a lower requested quality than the quality requested by the UE. In one example, the load distribution control unit 405 can control the E2 nodes to perform best-effort communication for which the required quality should be lowered. Since the details and modifications of this control are as described above, they will not be repeated here.

　Fig. 5 shows an example of the functional configuration of the E2 node. The E2 node includes, for example, an E2 communication unit 501, an O1 communication unit 502, a communication state information providing unit 503, and a load distribution processing unit 504 as its functions. The E2 communication unit 501 sets the E2 interface with the Near-RT RIC to perform communication. The O1 communication unit 502 sets the O1 interface with the Non-RT RIC to perform communication. The communication state information providing unit 503 provides information indicating the state of communication in its own device to the Non-RT RIC via the O1 interface and to the Near-RT RIC via the E2 interface. The information provided to Non-RT RIC is for long-term analysis such as 1 second or longer, and the information provided to Near-RT RIC is for short-term analysis such as less than 1 second. It is information for Since examples of information are as described above, they will not be repeated here. The load distribution processing unit 504 receives control from the Near-RT RIC and executes processing for handing over the designated UE to another designated cell. In addition, even if the load distribution processing unit 504 is not controlled by the Near-RT RIC, the load distribution processing unit 504 exchanges information with other surrounding E2 nodes and executes local load distribution processing. good too. In addition, as an option, the load distribution processing unit 504, if the communication quality to be satisfied is not obtained even if the load distribution control is executed (when the SLA achievement rate is insufficient in each network slice), some network slice/QoS flow communication quality control can be performed. Also, the load distribution processing unit 504 can control the E2 node to perform a new communication request with a lower requested quality than the quality requested by the UE. These controls can be executed, for example, by at least one of the load distribution control unit 405 of the Near-RT RIC and the load distribution processing unit 504 of the E2 node.

It should be noted that the E2 node has a function as a general base station device, and processes such as allocation of physical resource blocks to UEs are performed in the E2 node. In other words, the E2 node executes load distribution control according to the control of the Near-RT RIC, but the control by the Near-RT RIC only issues instructions, and the processing of connection control and resource allocation with each UE is performed by the E2 node. Nodes can run independently.

(Processing flow)
FIG. 6 shows an example of the flow of processing executed by Non-RT RIC. Non-RT RIC receives information indicating the state of communication from the E2 node (load state for each cell, UE, slice, information that can identify the SLA achievement rate for each network slice, received signal quality at the UE information, etc.), and for example, information such as congestion prediction information based on events and communication history is acquired from network operators, etc., and based on that information, the cells / network slices / A QoS class is determined (S601). It should be noted that it is sufficient if the target of load distribution control in the Near-RT RIC can be restricted, and the restriction does not necessarily have to be made by the cell/network slice/QoS class. Also, although the case where the processing executed in the Near-RT RIC and the E2 node is load distribution control is described here, the target of the processing may be determined with respect to other processing. Then, the Non-RT RIC generates policy information (A1 policy) containing information indicating the control target determined in S601 and information indicating that load distribution control should be executed, and the Near-RT RIC (S602). Note that the Non-RT RIC may periodically execute this process, and notify the Near-RT RIC of the information each time it is necessary to update the controlled object or the process to be executed. The A1 policy may have an expiration date, and the Non-RT RIC may update the A1 policy before the expiration date.

Fig. 7 shows an example of the flow of processing executed by Near-RT RIC. When the Near-RT RIC acquires the A1 policy from the Non-RT RIC, it controls the subordinate E2 nodes based on the A1 policy. In this embodiment, the Near-RT RIC monitors objects (cells/network slices/QoS classes) specified as objects of load distribution control according to the A1 policy for congestion (S701). Near-RT RIC, based on the results of its monitoring, decides to execute load distribution control (S702), for example, based on information obtained from the E2 node under its control, the other A UE to be handed over to the cell is determined, and an instruction (policy information/control information) is transmitted to the E2 node to execute handover processing for the UE (S703). In addition, Near-RT RIC will monitor changes in the congestion status of the E2 nodes under its control and the improvement status of the SLA achievement rate, etc., and will be the target of handover in S703 when executing the processing in FIG. 7 again after that. UE decision criteria (e.g., the weighting factor of the evaluation function) may be updated.

In addition, the Near-RT RIC can be used even if the UE determined in S703 is handed over, if the high load state continues with respect to the target of load distribution control (for example, the load of the cell in the high load state has not decreased sufficiently). If so), for at least some of the currently communicating network slices/QoS flows/UEs, a process of lowering the requested quality (changing to another acceptable network slice/QoS class) is performed (S704). As described above, for example, control is performed such that some network slices/QoS flows/UE communications are performed on a best-effort basis. At this time, Near-RT RIC, before lowering the requested quality, performs negotiation with the UE subject to the lowering of the requested quality, and if the requested quality lowering is accepted, the request Quality reduction control may be performed. Note that, in one example, a process of disconnecting communication may be performed when the reduction in required quality is unacceptable. Also, when a new communication is requested while the high load state continues, the Near-RT RIC can set the requested quality of the communication to be lower than the quality requested by the UE. In this case, too, negotiation of a lower quality connection may be performed before the requested quality reduction process is actually performed. Whether or not the high load state continues can be determined, for example, after the completion of handover processing, when the probability of satisfying the required quality in communication of one or more predetermined network slices/QoS flows with high priority is equal to or greater than a predetermined value. can be determined by whether or not After that, the Near-RT RIC re-changes the requested quality of the communication whose requested quality has been changed in accordance with the load reduction and improvement of the high load state (S705). In other words, Near-RT RIC restores the required quality (or increases the required quality within an acceptable range and does not exceed the original required quality) for communications that have lowered the required quality. . As a result, for example, communication of a network slice/QoS flow with a low priority can be continued with the required quality lowered, and as the load condition improves, the communication can be provided in line with the original required quality. be able to.

FIG. 8 shows an example of the flow of processing executed by the E2 node. The E2 node notifies the Non-RT RIC and the Near-RT RIC of information indicating the state of communication between the E2 node and the UE (S801). In addition, the E2 node provides non-RT RIC with information that enables analysis of long-term traffic fluctuations, etc., and near-RT RIC can execute short-term load distribution control. can provide information to Examples of the information provided are as described above and will not be repeated here. After that, the E2 node executes load distribution processing under the control of the Near-RT RIC (S802). For example, when the E2 node receives policy information/control information indicating that the connected UE should be handed over to another cell from the Near-RT RIC, based on that information, the UE is designated Execute the process of handing over to the cell. Also, the E2 node can perform connection processing for a UE handed over from another cell based on the policy information/control information received from the Near-RT RIC. Also, when the high load state continues after the UE is handed over, the E2 node requests a specific network slice/QoS flow/UE based on the policy information/control information received from the Near-RT RIC. Quality may be reduced (S803). In addition, the E2 node executes processing to autonomously lower the required quality of communication for a specific network slice/QoS flow, for example, for the UE connected to its own device, without following instructions from the Near-RT RIC. good too. After that, the E2 node changes again the requested quality of the communication whose requested quality has been changed based on the policy information/control information received from the Near-RT RIC in response to the improvement of the high load state ( S804). This process may also be autonomously executed by the E2 node.

As described above, the policy setting by the Non-RT RIC enables the Near-RT RIC to perform load distribution control in consideration of the communication status of many E2 nodes. At this time, the Non-RT RIC can specify the cells and network slices/QoS classes that are subject to load distribution control in the Near-RT RIC so that load distribution can be performed within a limited range. As a result, it is possible to perform load distribution control that considers the conditions of a large number of E2 nodes while suppressing the control load of the Near-RT RIC. In addition to or instead of load distribution control by UE handover, communication services are provided by lowering the required quality for low priority communications (for example, communications in network slices that allow service outages). By performing the control, it becomes possible to provide a communication service that satisfies the required quality for high-priority communication while securing the communication opportunity for that communication.

As a result, it will be possible to improve overall service quality in mobile communication systems, for example. It will be possible to contribute to the promotion of industrialization and the expansion of innovation.

The invention is not limited to the above embodiments, and various modifications and changes are possible within the scope of the invention.

This application claims priority based on Japanese Patent Application No. 2021-149559 submitted on September 14, 2021, and the entire contents of the description are incorporated herein.

Claims

A control method executed by a Near-RT (Real Time) RIC (RAN Intelligent Controller) of an O-RAN (Open-Radio Access Network),
Change the required quality of at least one of the first communication being executed by the E2 node and the newly accepted second communication for the E2 node that provides wireless communication to the terminal device in the O-RAN including providing information indicating what should be done;
control method.
2. The method according to claim 1, wherein the information indicates that at least one of the first communication and the second communication should be transitioned to a network slice with a required quality lower than the quality required for the communication. Described control method.
The control method according to claim 2, wherein the network slice is a network slice that performs best-effort communication.
4. Any one of claims 1 to 3, wherein the information indicates that QoS of a QoS (Quality of Service) flow should be reduced for at least one of the first communication and the second communication. The control method described in the item.
The control method according to claim 4, wherein the QoS corresponds to best effort.
A control method performed by an E2 node that provides wireless communication to a terminal device in an O-RAN (Open-Radio Access Network),
Near-RT (Real Time) RIC (RAN Intelligent Controller) to change the requested quality of at least one of the first communication executed by the E2 node and the newly accepted second communication obtaining information indicative of
executing control to change the requested quality of at least one of the first communication and the second communication based on the information;
Control method including.
7. The method according to claim 6, further comprising performing negotiation with a terminal device associated with said communication before changing the requested quality of at least one of said first communication and said second communication. Described control method.
The information indicates that at least one of the first communication and the second communication should be transitioned to a network slice with a required quality lower than the quality required for the communication,
For at least one of the first communication and the second communication, based on the information, further comprising performing a process of transitioning a network slice,
The control method according to claim 6 or 7.
the information indicates that QoS (Quality of Service) of at least one of the first communication and the second communication should be lowered;
For at least one of the first communication and the second communication, based on the information, further comprising executing a process to reduce QoS,
The control method according to any one of claims 6 to 8.
The control method according to any one of claims 6 to 9, further comprising re-changing the changed requested quality based on a reduction in the load on the E2 node.
A device that functions as an O-RAN (Open-Radio Access Network) Near-RT (Real Time) RIC (RAN Intelligent Controller),
Changing the required quality of at least one of the first communication being executed by the E2 node and the newly accepted second communication for the E2 node that provides wireless communication to the terminal device in the O-RAN having means for providing information indicating what to do,
Device.
A device that functions as an E2 node that provides wireless communication to a terminal device in an O-RAN (Open-Radio Access Network),
Near-RT (Real Time) RIC (RAN Intelligent Controller) to change the requested quality of at least one of the first communication executed by the E2 node and the newly accepted second communication an acquisition means for acquiring information indicating
execution means for executing control to change the required quality of at least one of the first communication and the second communication based on the information;
A device with
A computer provided in a device that functions as an O-RAN (Open-Radio Access Network) Near-RT (Real Time) RIC (RAN Intelligent Controller),
Changing the required quality of at least one of the first communication being executed by the E2 node and the newly accepted second communication for the E2 node that provides wireless communication to the terminal device in the O-RAN to provide information indicating what to do,
program for.
A computer provided in a device that functions as an E2 node that provides wireless communication to terminal devices in O-RAN (Open-Radio Access Network),
Near-RT (Real Time) RIC (RAN Intelligent Controller) to change the requested quality of at least one of the first communication executed by the E2 node and the newly accepted second communication get the information shown,
Based on the information, executing control to change the required quality of at least one of the first communication and the second communication;
program for.