Wireless communication system, path switching method thereof, and computer readable storage medium

Abstract

Each virtualized base station is configured by connecting a CU, a DU, and an RU via a predetermined path, and interfaces between the units are opened. An ACC is mounted on at least a portion of a computer in which each unit is virtualized. And each unit informs the RAN controller of the ACC information and the service information. The RAN controller is provided with: a path calculation unit (101) that calculates an optimal path on the basis of the ACC information and traffic information of each unit; and a path notification unit that notifies each unit of the information of the optimal path. Each unit switches the paths between the units on the basis of the notified path information.

Description

Technical Field

[0001] The present invention relates to a wireless communication system and a path switching method thereof. In particular, the present invention relates to a wireless communication system that achieves load balancing by switching connections between units of virtualized wireless base stations in a radio access network (RAN) based on the capabilities of a computer that virtualizes the wireless base stations, thereby improving the processing capacity and power consumption efficiency of the RAN. Background Art

[0002] With the evolution of fifth-generation wireless communication systems (5G), the demand for high-capacity, low-latency, and multi-connection communications is expected to increase further compared to the initial stage of introduction.

[0003] In addition, in O-RAN, specifications for splitting the functions of wireless base stations traditionally integrated in the RAN into a centralized unit (CU) that performs session processing, a distributed unit (DU) that performs baseband processing, and a wireless unit (RU) that performs wireless processing, as well as specifications for opening interface specifications between each unit (non-patent document 1), are being studied.

[0004] The O-RAN Alliance is also working on specifications for a RAN controller (RIC: RAN Intelligent Controller) that controls the RAN in an integrated manner. Furthermore, from the perspective of cost reduction and ease of operation, virtualized base stations, including the CU and DU, are being considered, implemented as software on general-purpose servers.

[0005] On the other hand, it is assumed that the processing load of CU and DU will increase in order to handle the increased traffic load due to the evolution of 5G. Patent document 1 studies a technology for dynamically increasing / decreasing the number of virtual base stations according to the processing load.

[0006] In addition, in order to handle the increased processing load on the CPU in the virtualized base station, patent document 2, non-patent document 2, and non-patent document 3 consider technologies for reducing the processing load on the CPU by offloading the CPU's 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).

[0007] Current technical literature

[0008] Patent Literature

[0009] Patent Document 1: Japanese Patent Application Laid-Open No. 2021-523186

[0010] Patent Document 2: Japanese Patent No. 7097340

[0011] Non-patent literature

[0012] Non-Patent Document 1: "O-RAN ALLIANCE," https: / / www.o-ran.org /

[0013] Non-patent document 2: Ryuta et al., "Quantitative evaluation of the power consumption reduction project of the Imagination Base Bureau" ," Journal of Information Science and Technology, vol.122, no.129, CQ2022-19, pp.13-18, July 2022.

[0014] Non-patent literature 3: JC Borromeo et al., “An Overview of Hardware Acceleration Techniques for 5G Functions,” 2020 22nd International Conference on Transparent Optical Networks, July 2020. Summary of the Invention

[0015] Problems to be solved by the invention

[0016] To cope with the large volume of traffic generated by the evolution of 5G, it is assumed that the processing load on the CPU in the virtualized base station will increase, and the CPU will be unable to handle traffic alone. According to the technology disclosed in Patent Document 1, the number of virtualized base stations can be increased or decreased. However, since it does not improve the processing power of the CPU, it is difficult to distribute the CPU processing.

[0017] Furthermore, in the technology disclosed in Patent Document 1, an ACC can be dynamically assigned to each function of a virtualized base station. However, since each function of a virtualized base station requires low latency, all virtualized base stations need to include an ACC.

[0018] In the technologies disclosed in Non-Patent Documents 2 and 3, the CPU processing load can be reduced by using an ACC. The ACC is more suitable than the CPU for computational processing in a virtualized base station. However, there is a problem of significantly increased costs when the ACC is installed in all CUs and DUs.

[0019] Means used to solve problems

[0020] According to one aspect of the present disclosure, a wireless communication system controls multiple virtualized base stations through a RAN controller, each virtualized base station being composed of a CU, a DU, and a RU connected via a predetermined path, and the interfaces between the units being open, wherein at least a portion of the computer virtualizing each unit is equipped with an accelerator, and each unit notifies the RAN controller of information about the accelerator and service information carried by the computer virtualizing itself. The RAN controller has: a mechanism for calculating the path connecting the units based on the accelerator information and service information notified from the units; and a mechanism for notifying the units of the path information, and the units switch the path based on the notified path information.

[0021] Effects of the Invention

[0022] According to the present invention, in the computer that virtualizes the wireless base station of the RAN, the capabilities of the units (CU, DU) virtualized by the computer equipped with the ACC are evaluated as higher than those of other units, and the paths between the units are switched so that the units with higher capabilities can handle more services. Therefore, efficient RAN operation can be achieved with minimal hardware resources.

[0023] Other features and advantages of the present invention will become clear from the following description with reference to the accompanying drawings. It should be noted that in the accompanying drawings, the same or similar structures are marked with the same reference numerals. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a functional block diagram showing the configuration of a main part of a radio access network (RAN) to which the present invention is applied.

[0025] Figure 2 This is a sequence flow showing an ACC information notification process in which each unit of the virtual base station notifies the RIC of information on the ACC mounted in the computer.

[0026] Figure 3 This is a sequence flow showing a service information notification process in which each unit of the virtual base station periodically notifies the RIC of current service information.

[0027] Figure 4 This is a sequence flow showing the path switching process in which the RIC calculates the optimal path between each unit and instructs each unit to switch the path.

[0028] Figure 5 is a functional block diagram illustrating an example of path switching. DETAILED DESCRIPTION

[0029] The following embodiments are described in detail with reference to the accompanying drawings. It should be noted that the following embodiments do not limit the inventions described herein. Furthermore, not all combinations of features described in the embodiments are essential to the invention. Any combination of two or more of the multiple features described in the embodiments may be used. Identical or similar components are denoted by the same reference numerals, and duplicate descriptions are omitted.

[0030] Figure 1 1 is a functional block diagram showing a configuration of a main part of a radio access network (RAN) to which the present invention is applied, and configurations unnecessary for explaining the present invention are omitted here.

[0031] In this embodiment, each wireless base station is constructed by connecting various units via predetermined paths. These units are the central unit (CU: CU-A, CU-B), distributed units (DU: DU-A, DU-B, DU-C), and radio units (RU: RU-A, RU-B, RU-C, RU-D). The interfaces between the CUs, DUs, and RUs are standardized and open, conforming to the O-RAN Alliance's specifications.

[0032] Each wireless base station is a virtualized base station implemented using virtualization technology that combines a general-purpose computer (e.g., a server) with software. At least a portion of the computer implementing the CU and DU is equipped with an FPGA or GPU that acts as an accelerator (ACC) to assist the computer's CPU.

[0033] The CU of each virtualized base station is connected to the core network (CN) via the backhaul (BH). Each CU and each DU are connected in a mesh mode via the midhaul (MH). Each DU and each RU are connected in a mesh mode via the fronthaul (FH). Each RU is equipped with an antenna (ANT) and wirelessly communicates with multiple user terminals (UEs).

[0034] Each CU and DU is connected to the RIC via a control signal interface. This control signal interface is used when each CU and DU sends statistical information to the RIC, or when the RIC sends control information to each CU and DU. The RIC includes a path calculation unit 101 and a path notification unit 102.

[0035] The path calculation unit 101 calculates the optimal path between units (CU, DU) based on information from the ACC, which is installed in the computer that virtualizes each unit, and the service information of each unit. The path notification unit 102 notifies each unit of the calculated optimal path. Each unit switches paths between units based on the path information notified from the RIC. The operations of the path calculation unit 101 and the path notification unit 102 will be described in detail later.

[0036] Figure 21 is a sequence flow showing an initial registration process in which each unit first registers its own ACC information with the RIC in a process for distributing traffic loads of each virtualized base station by dynamically switching paths between each unit of the CU, DU, and RU.

[0037] At time t1, when a CU first connects to the RAN or reboots, it sends the following information as ACC information to the RIC via the control signal interface at time t2: information indicating whether an ACC is installed on the computer implementing the CU using virtualization technology, and, if so, information indicating the ACC model and type as a capability indicator. At time t3, the RIC evaluates each CU's capabilities based on the ACC information received from it, and registers / updates the information as CU information.

[0038] Similarly, at time t4, when a DU connects to the RAN for the first time or reboots, the DU sends the following information as ACC information to the RIC via the control signal interface at time t5: information indicating whether an ACC is installed on the computer implementing the DU using virtualization technology, and if so, information indicating the ACC model and type as an indicator of its capabilities. At time t6, the RIC evaluates the capabilities of each DU based on the ACC information received from it, and registers / updates the information as DU information.

[0039] Figure 3 1 is a sequence flow illustrating a traffic information notification process in a process for distributing traffic loads of virtualized base stations by dynamically switching paths between units, wherein each unit periodically notifies the RIC of its current traffic information.

[0040] When the RAN is operating and traffic control starts, each CU notifies the RIC of the number of UEs connected to its subordinate RUs and the traffic volume as traffic information at time t7 (predetermined period: for example, every minute) via the control signal interface.

[0041] Similarly, each DU notifies the RIC of the number of UEs connected to its subordinate RUs and the traffic volume as traffic information at time t8 (predetermined period: for example, every minute) via the control signal interface.

[0042] At time t9, the RIC repeatedly performs load prediction based on the traffic information of each unit notified by each CU and DU and the number of UEs connected to the subordinate DUs of each unit to determine whether there is a sign of increased traffic in the RAN.

[0043] Figure 4FIG. 1 is a sequence flow illustrating a path switching process in a process for distributing traffic loads of virtualized base stations by dynamically switching paths between units, wherein the RIC calculates an optimal path and instructs each unit to switch paths.

[0044] When the RIC detects signs of increased traffic in the RAN through load prediction based on the traffic information regularly 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, thereby achieving a balanced distribution of the traffic processing load among each CU and DU.

[0045] In this embodiment, the capabilities of units (CUs and DUs) virtualized by a computer equipped with an ACC are evaluated as higher than those of units virtualized by a computer without an ACC. Paths are then calculated between each CU, DU, and RU, connecting CUs and DUs with higher capabilities to RUs connected to a greater number of UEs.

[0046] For example, Figure 5 As shown in FIG, if a sign of increased traffic is detected due to an increase in the number of UEs connected to RU-C, and there is only one DU virtualized on the computer equipped with an ACC (for example, DU-B), a path connecting DU-B and RU-C is calculated. Furthermore, if there is only one CU virtualized on the computer equipped with an ACC (for example, CU-A), a path connecting CU-A and DU-B is calculated.

[0047] Furthermore, if the capabilities of the ACC can be evaluated in more detail based on its model, the path can be optimized based on the capabilities of the ACC. For example, if two DUs (e.g., DU-A and DU-B) are virtualized on a computer equipped with an ACC, and the capabilities of the ACC on the computer virtualizing DU-A are higher than those on the computer virtualizing DU-B, the path is calculated so that, of the top two RUs with the largest number of connected UEs, the one with the largest number of connected UEs is connected to DU-A, and the other is connected to DU-B.

[0048] When the path calculation is completed, at time t11, the RIC notifies each CU of connection destination DU information specifying the connection destination DU via the control interface. At time t12, the RIC notifies each DU of connection destination RU information specifying the connection destination RU via the control interface.

[0049] At time t13, each CU switches the connection destination DU to the designated DU based on the connection destination DU message notified by the RIC. At time t14, each DU switches the connection destination RU to the designated RU based on the connection destination RU message notified by the RIC.

[0050] According to the present invention, in the computer that virtualizes the wireless base stations of the RAN, the capabilities of the units virtualized by the computer equipped with the ACC are evaluated as higher than those of other units, and the paths between the units are switched so that the units with higher capabilities can handle more business. This enables efficient RAN operations with minimal computing resources.

[0051] Furthermore, according to the above-described embodiments, communication quality such as wireless communication throughput and delay time can be improved using minimal hardware resources, making it possible to provide various communications and entertainment to multiple people regardless of geographical or economic differences.

[0052] Furthermore, according to the present disclosure, a computer program for causing a device having one or more processors to function as the RIC and a computer program for causing a device to execute the path switching method are provided. Furthermore, a non-transitory computer-readable storage medium having the computer program stored thereon is provided.

[0053] The present invention is not limited to the above embodiments, and various changes and modifications can be made within the spirit and scope of the present invention. Therefore, in order to inform the public of the scope of the present invention, the following claims are made.

[0054] This application claims the benefit of Japanese Patent Application No. 2023-01317, filed on January 31, 2023, which is hereby incorporated by reference herein in its entirety.

Claims

1. A wireless communication system in which a RAN controller controls virtualized base stations, each of which is composed of a central unit (CU), a distributed unit (DU), and a radio unit (RU) connected via a predetermined path, with interfaces between the units being open, wherein: At least a portion of the computer that virtualizes each unit is equipped with an accelerator. Each unit notifies the RAN controller of information about the accelerators and service information on the computers virtualized by each unit itself. The RAN controller comprises: A mechanism for calculating a path connecting each unit based on accelerator information and business information notified from each unit; and Notify the information of the path to the mechanism of each unit, Each of the units switches the path based on the notified information about the path.

2. The wireless communication system according to claim 1, wherein The RAN controller further includes a mechanism for predicting the load of the RAN based on the traffic information notified from each unit. The mechanism for calculating the path calculates the path based on the predicted load of the RAN and information about the accelerator.

3. The wireless communication system according to claim 1 or 2, wherein: The traffic information is at least one of the number of user terminals connected to the RUs under each unit and the traffic volume.

4. The wireless communication system according to any one of claims 1 to 3, wherein: The accelerator information includes information related to the presence or absence of the accelerator. The mechanism for calculating the path evaluates the capabilities of units virtualized by a computer equipped with an accelerator as being higher than the capabilities of units virtualized by a computer not equipped with an accelerator, and calculates a path in which the units with higher capabilities are assigned more traffic.

5. The wireless communication system according to claim 4, wherein: The accelerator information includes information that is an indicator of the accelerator's capability. The mechanism for calculating the path evaluates the capabilities of the units virtualized by the computers with higher capabilities of the accelerator as higher, and calculates the path in which the units with higher capabilities bear more traffic.

6. A path switching method for a wireless communication system, wherein the wireless communication system controls virtualized base stations via a RAN controller, each virtualized base station being configured by connecting a session unit (CU), a distributed unit (DU), and a radio unit (RU) via a predetermined path, with interfaces between the units being open, wherein: At least a portion of the computer that virtualizes each unit is equipped with an accelerator. Each unit notifies the RAN controller of information about the accelerators and service information on the computers virtualized by each unit itself. The RAN controller performs: Calculating a path connecting each unit based on the accelerator information and business information notified from each unit; as well as Notify each unit of the path information, Each of the units switches the path based on the notified information about the path.

7. The path switching method of a wireless communication system according to claim 6, wherein: The accelerator information includes information related to the presence or absence of the accelerator. The capability of a unit virtualized by a computer equipped with an accelerator is evaluated as higher than the capability of a unit virtualized by a computer not equipped with an accelerator, and a path is calculated in which the unit with higher capability is assigned more traffic.

8. The path switching method of the wireless communication system according to claim 7, wherein: The accelerator information includes information that is an indicator of the accelerator's capability. The capability of a unit virtualized by a computer with higher accelerator capability is evaluated higher, and a path is calculated in which the unit with higher capability carries more traffic.

9. A computer-readable storage medium, wherein: The computer-readable storage medium stores a computer program, which, when executed by one or more processors of a device having one or more processors, performs the path switching method according to any one of claims 6 to 8.

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