Wireless communication system, its route switching method, and route switching program

Abstract

To provide a RAN configured by a virtualized base station, where a RIC grasps an accelerator ACC mounted on a computer virtualizing each unit and determines a unit capable of traffic processing depending on a predicted traffic demand to select a path.SOLUTION: Each virtualized base station is configured by connecting respective units CU, DU, and RU using a predetermined path, where interfaces among the respective units are opened. An ACC is mounted on at least one or some of computers virtualizing the respective units. The respective units report ACC information and traffic information on the computers to a RAN controller. The RAN controller comprises a path calculation unit 101 for calculating an optimal path on the basis of the ACC information and the traffic information of the respective units; and a path reporting unit 102 for reporting information on the optimal path to the respective units. On the basis of the reported path information, the respective units switch a path among the units.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a wireless communication system, a route switching method, and a route switching program thereof. In particular, according to the capabilities of a computer that virtualizes radio base stations in a RAN (Radio Access Network), the connection between units of each virtualized base station is switched to achieve load distribution, and a wireless communication system for improving the processing capacity and power consumption efficiency of the RAN, as well as a route switching method and a route switching program thereof.

Background Art

[0002] With the advancement of the fifth-generation wireless communication system (5G), it is assumed that the demand for high-capacity, low-latency, and multi-connection communication will further increase compared to the initial introduction stage.

[0003] In addition, the functions of radio base stations that were conventionally integrated in the RAN are divided into a CU (Centralized Unit) that performs session processing, a DU (Distributed Unit) that performs baseband processing, and a RU (Radio Unit) that performs radio processing, and the O-RAN Alliance (Non-Patent Document 1) is proceeding with a specification study to open the interface specifications between each unit.

[0004] The O-RAN Alliance is also further proceeding with a specification study on a RAN controller (RIC: RAN Intelligent Controller) for integrally controlling the RAN. Also, from the viewpoints of cost reduction and ease of operation, in particular, a study of virtualized base stations implemented as software on general-purpose servers for the CU and DU is being advanced.

[0005] On the other hand, in order to handle the traffic load increased by the advancement of 5G, it is assumed that the processing loads of the CU and DU will increase. A technique for dynamically increasing and reducing the number of virtualized base stations according to the processing load is being studied in Patent Document 1.

[0006] Furthermore, in order to address the increased processing load on the CPU in virtualized base stations, technologies to reduce the CPU processing load by offloading CPU processing to accelerators (ACCs) such as FPGAs (Field-Programmable Gate Arrays: integrated circuits whose configuration can be set by the purchaser or designer after manufacturing) and GPUs (Graphics Processing Units) have been examined in Patent Document 2 and Non-Patent Documents 2 and 3. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2021-523186 [Patent Document 2] Patent No. 7097340 [Non-patent literature]

[0008] [Non-Patent Document 1] "O-RAN ALLIANCE," https: / / www.o-ran.org / [Non-Patent Document 2] Nagareta et al., "Quantitative Evaluation of Power Consumption Reduction through Hardware Offloading of Virtualized Base Stations," IEICE Technical Report, vol. 122, no. 129, CQ2022-19, pp. 13-18, July 2022. [Non-Patent Document 3] JC Borromeo, et al.,"An Overview of Hardware Acceleration Techniques for 5G Functions," 2020 22nd International Conference on Transparent Optical Networks, July 2020. [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] To cope with the high-capacity traffic resulting from the advancement of 5G, it is anticipated that the processing load on the CPU in virtualized base stations will increase, making it impossible for the CPU alone to handle the workload. While the technology disclosed in Patent Document 1 allows for increasing or decreasing the number of virtualized base stations, it does not improve the CPU's processing power, making it difficult to distribute the processing load to the CPU.

[0010] Furthermore, while the technology disclosed in Patent Document 1 allows for the dynamic assignment of ACC to each function of a virtualized base station, all virtualized base stations need to contain ACC because each function of the virtualized base station requires low latency.

[0011] The technologies disclosed in Non-Patent Documents 2 and 3 make it possible to reduce the CPU processing load by using an ACC (Access Control Unit), which is more suitable than the CPU for computational processing in virtualized base stations. However, there is a problem that costs increase significantly if ACCs are installed in all CUs and DUs.

[0012] The object of the present invention is to solve the above technical problems and to provide a wireless communication system, a route switching method, and a route switching program that enable the RIC to understand the ACC and traffic processing load installed in the computer that virtualizes the CU and DU in a RAN composed of multiple virtualized base stations, and to optimize the route connecting the CU and DU according to the predicted traffic demand. [Means for solving the problem]

[0013] To achieve the above objective, the present invention provides a wireless communication system in which a RAN controller controls a plurality of virtualized base stations, each virtualized base station is configured by connecting CUs, DUs, and RUs via predetermined paths, and the interfaces between each unit are open. In this system, at least a portion of the computers that virtualize each unit are equipped with accelerators, each unit notifies the RAN controller of information about the accelerators and traffic information installed in the computer that virtualizes it, the RAN controller comprises means for calculating a path connecting each unit based on the accelerator information and traffic information notified by each unit, and means for notifying each unit of the path information, and each unit switches paths based on the notified path information. [Effects of the Invention]

[0014] According to the present invention, among the computers that virtualize the RAN's wireless base stations, the computer equipped with ACC evaluates the capabilities of the virtualized units (CU, DU) more highly than other units, and the paths between each unit are switched so that the unit with higher capability can handle more traffic, thereby enabling efficient RAN operation with minimal hardware resources. [Brief explanation of the drawing]

[0015] [Figure 1] This is a functional block diagram showing the configuration of the main parts of a wireless access network (RAN) to which the present invention is applied. [Figure 2] This is a sequence flow illustrating the procedure for notifying the RIC (Radio Control Center) of ACC information, which is transmitted from each unit of a virtual base station to the RIC (Radio Control Center) via a computer. [Figure 3] This is a sequence flow illustrating the traffic information notification procedure in which each unit of a virtual base station periodically notifies the RIC of current traffic information. [Figure 4] This is a sequence flow illustrating the route switching procedure in which the RIC calculates the optimal route between each unit and instructs each unit to switch routes. [Figure 5] This is a functional block diagram showing an example of path switching. **Embodiments for Carrying out the Invention**

[0016] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a functional block diagram showing the configuration of the main part of a radio access network (RAN) to which the present invention is applied, and here, configurations unnecessary for the description of the present invention are omitted.

[0017] In this embodiment, each radio base station is configured by connecting each unit of a session unit (CU: CU - A, CU - B), a distributed unit (DU: DU - A, DU - B, DU - C), and a radio unit (RU: RU - A, RU - B, RU - C, RU - D) through a predetermined path. The interfaces between each CU, DU, and RU are standardized and opened in accordance with the specifications of the O - RAN Alliance.

[0018] Each radio base station is a virtualized base station realized by virtualization technology that combines software with a general - purpose computer (for example, a server device). At least a part of the computers that realize the CU and DU are equipped with an FPGA or a GPU as an accelerator (ACC) that assists the CPU of the computer.

[0019] The CU of each virtualized base station is connected to a core network (CN) and a backhaul (BH). Each CU and each DU are connected in a mesh shape through a mid - haul (MH). Each DU and each RU are connected in a mesh shape through a front - haul (FH). An antenna (ANT) is provided in each RU, and wireless communication is performed with many user terminals (UE).

[0020] Each CU and DU are connected to a RIC through a control signal interface. The control signal interface is used when each CU and DU transmit statistical information to the RIC or when the RIC transmits control information to each CU and DU. The RIC includes a path calculation unit 101 and a path notification unit 102.

[0021] The route calculation unit 101 calculates the optimal route between each unit (CU, DU) based on the ACC information installed in the computer that virtualizes each unit and the traffic information of each unit. The route notification unit 102 notifies each unit of the calculated optimal route information. Each unit switches the route between units based on the route information notified by the RIC. The operation of the route calculation unit 101 and the route notification unit 102 will be described in detail later.

[0022] Figure 2 is a sequence flow showing the initial registration procedure in which each unit registers its own ACC information with the RIC, which is part of the procedure for dynamically switching routes between CU, DU, and RU units to distribute the traffic load of each virtualized base station.

[0023] At time t1, when a CU is first connected to the RAN or restarted, at time t2, the CU transmits information to the RIC via the control signal interface as ACC information, indicating whether the computer that is implementing it using virtualization technology has an ACC, and if so, the model number and type of the ACC, which are indicators of the ACC's capabilities. At time t3, the RIC evaluates the capabilities of each CU based on the ACC information received from each CU and updates and registers it as CU information.

[0024] Similarly, at time t4, if a DU is connected to the RAN for the first time or restarted, at time t5, the DU transmits information to the RIC via the control signal interface as ACC information, indicating whether the computer that is implementing it using virtualization technology has ACC, and if so, information indicating its capability. At time t6, the RIC evaluates the capability of each DU based on the ACC information received from each DU and updates and registers it as DU information.

[0025] Figure 3 is a sequence flow showing the traffic information notification procedure, which is part of the process of dynamically switching routes between units to distribute the traffic load of each virtualized base station, and in which each unit periodically notifies the RIC of its current traffic information.

[0026] When the RAN is operational and traffic control begins, each CU notifies the RIC via the control signal interface at time t7 (a predetermined period: for example, a 1-minute period) of traffic information, including the number of UEs connected to the RU under its control and the amount of traffic.

[0027] Similarly, each DU also notifies the RIC via the control signal interface at time t8 (a predetermined period: for example, a 1-minute period) of traffic information, including the number of UEs connected to its subordinate RUs and the amount of traffic.

[0028] At time t9, the RIC repeatedly performs load predictions to determine whether there are signs of increased traffic in the RAN, based on traffic information from each CU and DU, and the number of UEs connected to the DUs under each unit.

[0029] Figure 4 is a sequence flow showing the route switching procedure, which is part of the process of dynamically switching routes between units to distribute the traffic load of each virtualized base station. Specifically, it shows the RIC calculating the optimal route and instructing each unit to switch routes.

[0030] When the RIC detects an indication of increased traffic in the RAN based on load predictions using traffic information periodically notified from each CU and DU, at time t10, it calculates the optimal path between each CU, DU, and RU based on the load prediction results and the ACC information of each unit, so that the traffic processing load is distributed to each CU and DU.

[0031] In this embodiment, the capabilities of units (CU, DU) virtualized by a computer equipped with ACC are evaluated as higher than the capabilities of units virtualized by a computer without ACC. The paths between each CU, DU, and RU are calculated so that CUs and DUs with higher capabilities are connected to RUs with a larger number of connected UEs.

[0032] For example, as shown in Figure 5, an increase in the number of UEs connected to RU-C indicates an increase in traffic. If there is one DU (e.g., DU-B) virtualized on the computer equipped with ACC, a path connecting DU-B to RU-C is calculated. Furthermore, if there is one CU (CU-A) virtualized on the computer equipped with ACC, a path connecting CU-A to DU-B is calculated.

[0033] Furthermore, if the capabilities of the ACC can be evaluated in more detail based on its model number, the route may be optimized according to the capabilities of the ACC. For example, if there are two DUs (e.g., DU-A and DU-B) virtualized by a computer equipped with an ACC, and the capabilities of the ACC installed in the computer virtualizing DU-A are higher than the capabilities of the ACC installed in the computer virtualizing DU-B, then a route is calculated that connects the RU with the higher number of connected UEs to DU-A and the other to DU-B.

[0034] Once the route calculation is complete, at time t11, the RIC notifies each CU via the control interface of the destination DU information, which identifies the destination DU. At time t12, the RIC notifies each DU via the control interface of the destination RU information, which identifies the destination RU.

[0035] At time t13, each CU switches its connected DU to the DU specified in the connected DU information, based on the connected DU information notified by the RIC. At time t14, each DU switches its connected RU to the RU specified in the connected RU information, based on the connected RU information notified by the RIC.

[0036] According to this embodiment, the capabilities of the units virtualized by the computer equipped with ACC among the computers that virtualize the RAN's wireless base stations are evaluated more highly than those of other units, and the routes between each unit are switched so that the unit with higher capabilities can handle more traffic, thereby enabling efficient RAN operation with fewer computing resources.

[0037] Furthermore, according to the above embodiment, it becomes possible to improve communication quality such as throughput and latency of wireless communication with minimal hardware resources, thereby enabling the provision of diverse communication and entertainment to many people, transcending geographical and economic disparities. As a result, it becomes possible to contribute to Goal 9, "Build resilient infrastructure and promote inclusive and sustainable industrialization," and Goal 11, "Make cities inclusive, safe, resilient and sustainable." [Explanation of Symbols]

[0038] CU…Session Unit, DU…Distributed Unit, RU…Wireless Unit, ACC…Accelerator, CN…Core Network, BH…Backhaul, MH…Midhaul, 101…Route Calculation Unit, 102…Route Notification Unit

Claims

1. In a wireless communication system where virtualized base stations are controlled by a RAN controller, and each virtualized base station is configured by connecting session units (CUs), distributed units (DUs), and radio units (RUs) via predetermined paths, and the interfaces between each unit are open, At least part of the computer that virtualizes each unit is equipped with an accelerator, Each of the aforementioned units notifies the RAN controller of information about the accelerator installed in the computer that virtualizes itself, and traffic information. The RAN controller, A means for calculating the route connecting each unit based on accelerator information and traffic information notified from each unit, The system comprises means for notifying each unit of the information of the aforementioned route, A wireless communication system characterized in that each unit switches routes based on the notified route information.

2. The RAN controller further comprises means for predicting the load of the RAN based on traffic information notified from each of the units, The wireless communication system according to claim 1, characterized in that the means for calculating the route calculates the route based on the predicted RAN load and accelerator information.

3. The wireless communication system according to claim 1, characterized in that the traffic information is at least one of the number of user terminals connected to RUs under each unit and the amount of traffic.

4. The information of the accelerator includes information regarding the presence or absence of the accelerator. The means for calculating the aforementioned route is characterized in that it evaluates the capabilities of a unit virtualized by a computer equipped with an accelerator as higher than the capabilities of a unit virtualized by a computer without an accelerator, and calculates a route in which the unit with higher capabilities bears more traffic. This is the wireless communication system according to any one of claims 1 to 3.

5. The information of the accelerator includes information that serves as an indicator of the accelerator's capabilities. The means for calculating the route is characterized in that the accelerator's capability evaluates the capability of the virtualized unit more highly on the computer with higher capability, and calculates a route in which the unit with higher capability bears more traffic.

6. In a wireless communication system where virtualized base stations are controlled by a RAN controller, and each virtualized base station is configured by connecting session units (CUs), distributed units (DUs), and radio units (RUs) via predetermined paths, and the interfaces between each unit are open, a method for switching paths exists. At least part of the computer that virtualizes each unit is equipped with an accelerator, Each of the aforementioned units notifies the RAN controller of information about the accelerator installed in the computer that virtualizes itself, and traffic information. The RAN controller is Based on the accelerator information and traffic information notified from each unit, the system calculates the route connecting each unit. The information of the aforementioned route is notified to each of the aforementioned units, A method for switching routes in a wireless communication system, characterized in that each unit switches routes based on the notified route information.

7. The information of the accelerator includes information regarding the presence or absence of the accelerator. The method for switching routes in a wireless communication system according to claim 6, characterized in that the capabilities of a unit virtualized on a computer equipped with an accelerator are evaluated as higher than the capabilities of a unit virtualized on a computer without an accelerator, and a route is calculated in which the unit with higher capabilities bears more traffic.

8. The information of the accelerator includes information that serves as an indicator of the accelerator's capabilities. The method for switching routes in a wireless communication system according to claim 7, characterized in that the accelerator's capability evaluates the capability of the virtualized unit more highly on a computer with higher capability, and calculates a route in which the unit with higher capability bears more traffic.

9. In a wireless communication system where virtualized base stations are controlled by a RAN controller, and each virtualized base station is configured by connecting session units (CUs), distributed units (DUs), and radio units (RUs) via predetermined paths, and the interfaces between each unit are open, the routing program is configured as follows: At least part of the computer that virtualizes each unit is equipped with an accelerator, Each of the aforementioned units notifies the RAN controller of information about the accelerator installed in the computer that virtualizes itself, and traffic information. The aforementioned RAN controller, A procedure for calculating the route connecting each unit based on accelerator information and traffic information notified by each unit, The procedure involves notifying each unit of the information of the aforementioned route, A route switching program for a wireless communication system, characterized in that each unit switches routes based on the notified route information.

10. The information of the accelerator includes information regarding the presence or absence of the accelerator. The routing program for a wireless communication system according to claim 9, characterized in that, in the procedure for calculating the aforementioned route, the capability of a unit virtualized on a computer equipped with an accelerator is evaluated as higher than the capability of a unit virtualized on a computer without an accelerator, and a route is calculated in which the unit with higher capability bears more traffic.

11. The information of the accelerator includes information that serves as an indicator of the accelerator's capabilities. The routing program for a wireless communication system according to claim 10, characterized in that the procedure for calculating the aforementioned route evaluates the capabilities of virtualized units more highly on computers with higher accelerator capabilities, and calculates a route in which the units with higher capabilities bear more traffic.

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