Wireless communication system, communication control method, and computer program

Abstract

Ensure proper control of the handover process. [Solution] In an O-RAN specification wireless access network, the wireless communication system includes an interface for a Central Unit (CU) that controls handovers in subordinate Distributed Units (DUs) to acquire computing resource information related to the DUs.

Description

Technical Field

[0001] The present invention relates to a wireless communication system, a communication control method, and a computer program.

Background Art

[0002] The Open Radio Access Network (O-RAN) Alliance is considering the opening and intelligentization of next-generation radio access networks (RANs) such as the 5th generation (5G) mobile communication system (see, for example, Non-Patent Document 1). The O-RAN specifications established by the O-RAN Alliance include, for example, specifications regarding the O1 interface for information exchange between SMO (Service and Management Orchestration) that can monitor O-Cloud resources, O-CU (O-RAN Central Unit), and O-DU (O-RAN Distributed Unit).

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the conventional O-RAN specification described above, a CU (Central Unit) will respond to a handover request from the source CU with permission if the DU (Distributed Unit) under it is the handover destination, even if the DU does not have sufficient computing resources. As a result, the source base station sends an "RRC Reconfiguration" to the user equipment (UE) to be handed over, and the UE performs a RACH (Random Access Channel) procedure to the DU to be handed over. However, the DU to be handed over cannot respond to the RACH procedure due to insufficient computing resources, and the UE repeats the RACH procedure, which is a problem.

[0005] This invention was made in consideration of these circumstances, and its purpose is to ensure proper control of handovers. [Means for solving the problem]

[0006] One aspect of the present invention is a wireless communication system in which, in an O-RAN specification wireless access network, a Central Unit (CU) that controls handover in subordinate Distributed Units (DUs) has an interface for acquiring computing resource information related to the DUs. One aspect of the present invention is a wireless communication system in which the interface includes querying the computing resource information from the CU and responding to the computing resource information with the CU. One aspect of the present invention is a wireless communication system in which the interface includes periodic notification of computing resource information to the CU.

[0007] One aspect of the present invention is a communication control method performed by a wireless communication system, wherein in an O-RAN specification wireless access network, a Central Unit (CU) that controls handover in subordinate Distributed Units (DUs) acquires computing resource information relating to the DUs via a predetermined interface.

[0008] One aspect of the present invention is a computer program that causes a computer to perform the step of obtaining computing resource information relating to a Distributed Unit (DU) in an O-RAN-compliant wireless access network, via a predetermined interface, by which a Central Unit (CU) that controls handover in subordinate DUs (Distributed Units) acquires the DUs. [Effects of the Invention]

[0009] According to the present invention, the effect of being able to appropriately control handover can be obtained. [Brief explanation of the drawing]

[0010] [Figure 1] This is a block diagram showing a schematic configuration example of a wireless access network (RAN) of a wireless communication system according to one embodiment. [Figure 2] This figure shows the architecture of the RAN according to one embodiment of the O-RAN specification. [Figure 3] This figure shows an example of the procedure for a communication control method according to one embodiment. [Figure 4] This figure shows an example of the procedure for a communication control method according to one embodiment. [Figure 5] This figure shows an example of the procedure for a communication control method according to one embodiment. [Figure 6] This figure shows an example of the procedure for a communication control method according to one embodiment. [Modes for carrying out the invention]

[0011] Embodiments of the present invention will be described below with reference to the drawings. Figure 1 is a block diagram showing a schematic configuration example of a radio access network (RAN) of a wireless communication system according to one embodiment. The RAN1 shown in Figure 1 is subject to the O-RAN specification. However, in this embodiment, information not specified in the O1 interface of the O-RAN specification is newly added to the O1 interface.

[0012] RAN1 comprises an SMO (Service and Management Orchestration) 10, O-CU (O-RAN Central Unit) 20 (20-1, 20-2), O-DU (O-RAN Distributed Unit) 30 (30-1, 30-2), and Access Points (AP) #1, #2.

[0013] SMO10 sends and receives information to and from O-CU20 via the O1 interface. The O1 interface is defined in the O-RAN specification.

[0014] The O-CU20-1 controls the O-DU30-1 and other related functions. For example, the O-CU20-1 controls the handover process in the O-DU30-1.

[0015] The O-CU20-2 controls the O-DU30-2 and other related functions. For example, the O-CU20-2 controls the handover process in the O-DU30-2.

[0016] Figure 1 shows an example where user terminal (UE) #1, which is the target of the handover, performs a handover from AP#1, the source AP, to AP#2, the destination AP. The destination O-CU20-2 controls O-DU30-2 (the destination O-DU) which accommodates AP#2.

[0017] As illustrated in FIG. 1, for the O-DU 30, computing resources of accelerators (ACC-1, ACC-2, ···, ACC-n) are allocated from an O-Cloud (not shown). The accelerators are provided for each UE (UE-1, UE-2, ···, UE-n). For example, when all the accelerators of the O-DU 30-2 have already been allocated to UEs, the O-DU 30-2 does not have sufficient computing resources, and thus the O-DU 30-2 cannot accommodate a new UE by handover. The accelerator is also referred to as a hardware (HW) accelerator.

[0018] In the present embodiment, when the O-CU 20-2 at the handover destination determines that the subordinate O-DU 30-2 does not have sufficient computing resources when the O-DU 30-2 is the handover destination, the O-CU 20-2 at the handover destination attempts to respond with non-permission to the handover request from the O-CU 20-1 at the handover source. For this reason, in the present embodiment, the O-CU 20 includes an interface for acquiring computing resource information regarding the subordinate O-DU 30. Specifically, the computing resource information is added to the O1 interface so that the O-CU 20 can acquire the computing resource information regarding the O-DU 30 from the SMO 10 through the O1 interface. The SMO 10 can acquire the computing resource information regarding the O-DU 30 according to the existing O-RAN specification. FIG. 2 shows the RAN architecture of the O-RAN specification according to the present embodiment.

[0019] As a result, when the O-CU20-2 to which the handover destination is located determines that the O-DU30-2 under it does not have sufficient computing resources based on the computing resource information regarding the O-DU30-2 obtained from the SMO10 through the O1 interface in the case where the O-DU30-2 under it is the handover destination, it responds with non-permission to the handover request from the O-CU20-1 of the handover source. As a result, the O-CU20-1 of the handover source does not send "RRC Reconfiguration" to the UE#1 that is the handover target, so the UE#1 does not execute the RACH procedure for the O-DU30-2 of the handover destination, and therefore the RACH procedure is not repeated, and other handover destinations can be discovered earlier.

[0020] FIGS. 3 to 6 are diagrams showing examples of procedures of the communication control method according to the present embodiment.

[0021] In FIGS. 3 and 4, as examples of procedures of the communication control method according to the present embodiment, examples of procedures of querying (Query) and responding (Response) to computing resource information are shown. FIG. 3 shows the case of handover (Intra-CU HO) between O-DUs 30 under the same O-CU20. FIG. 4 shows the case of handover (Inter-CU HO) between O-DUs 30 under different O-CUs 20.

[0022] Referring to FIG. 3, the procedure of Query·Response in Intra-CU HO will be described.

[0023] (Step S1) The UE transmits a "Measurement Report" indicating that the O-DU30 of the target base station (Target gNB) satisfies the handover condition to the O-DU30 of the source base station (Source gNB).

[0024] (Step S2) Source base station O-DU30 sends "UL RRC Message Transfer" to source base station O-CU20. In Intra-CU HO, source base station O-CU20 and target base station O-CU20 are the same. Therefore, target base station O-CU20 receives "UL RRC Message Transfer" from source base station O-DU30.

[0025] (Step S3) The target base station's O-CU20 sends a query to the SMO10 via the O1 interface for computing resource information regarding the O-DU30 (the target base station's O-DU). As a result, a new query for computing resource information is added to the O1 interface.

[0026] (Step S4) SMO10 obtains computing resource information for the target base station's O-DU30 from O-Cloud via the Monitoring Service.

[0027] (Step S5) SMO10 responds to the target base station's O-CU20 via the O1 interface with computational resource information regarding the target base station's O-DU30. As a result, a new response (Response) of computational resource information is added to the O1 interface. The target base station's O-CU20 obtains computing resource information for the target base station's O-DU30 from the SMO10 via the O1 interface.

[0028] (Step S6) The target base station's O-CU20 determines whether to approve or reject the handover based on the computing resource information of the target base station's O-DU30.

[0029] From step S6 onward, the default handover procedure is executed.

[0030] Refer to Figure 4 to explain the Query-Response procedure in Inter-CU HO. In Figure 4, the parts corresponding to each step in Figure 3 are denoted by the same symbols, and their explanations are omitted.

[0031] Step S1 is the same as in Figure 3. Next, step S2a is executed.

[0032] (Step S2a) Source base station O-DU30 sends "UL RRC Message Transfer" to source base station O-CU20.

[0033] (Step S2b) The source base station's O-CU20 sends a Handover Request to the target base station's O-CU20.

[0034] Next, steps S3 through S6 are executed. Steps S3 through S6 are the same as in Figure 3. From step S6 onward, the default handover procedure is executed.

[0035] Figures 5 and 6 show an example of the procedure for periodically transmitting computing resource information as an example of the communication control method according to this embodiment. Figure 5 is for the Intra-CU HO case. Figure 6 is for the Inter-CU HO case. In the procedure in Figures 5 and 6, computing resource information concerning the O-DU30 under the control of the O-CU20 is periodically notified from the SMO10 to the O-CU20 via the O1 interface.

[0036] The procedure for periodic transmission in Intra-CU HO will be explained with reference to Figure 5. In Figure 5, the parts corresponding to each step in Figure 3 are denoted by the same reference numerals, and their explanations are omitted.

[0037] Steps S1 and S2 are the same as in Figure 3.

[0038] (Step S11) SMO10 periodically obtains computing resource information for O-DU30 from O-Cloud via the monitoring service.

[0039] (Step S12) SMO10 periodically sends computing resource information regarding the O-DU30 under the control of O-CU20 to O-CU20 via the O1 interface. Therefore, periodic notifications of computing resource information are newly added to the O1 interface. The O-CU20 periodically receives computing resource information about the O-DU30 under its control from the SMO10 via the O1 interface. The O-CU20 stores the computing resource information about the O-DU30 under its control.

[0040] (Step S13) The target base station's O-CU20 determines whether to approve or reject the handover based on the computing resource information for the target base station's O-DU30, which is among the computing resource information for the subordinate O-DU30s that it receives and holds from the SMO10.

[0041] From step S13 onward, the default handover procedure is executed.

[0042] The procedure for periodic transmission in Inter-CU HO will be explained with reference to Figure 6. In Figure 6, the parts corresponding to the steps in Figures 4 and 5 are denoted by the same reference numerals, and their explanations are omitted.

[0043] Steps S1, S2a, and S2b are the same as in Figure 4. Also, as in Figure 5, steps S11, S12, and S13 are executed. From step S13 onward, the default handover procedure is executed.

[0044] The following is an example of computing resource information.

[0045] An example of computing resource information is information about hardware (HW) accelerators. This information includes, for example, the utilization rate of HW accelerators, the availability of HW accelerators, and whether or not HW accelerators have been secured for newly added UEs.

[0046] An example of computing resource information is information about the O-Cloud's CPU (Central Processing Unit). CPU information includes, for example, CPU usage, CPU availability, and whether or not CPU resources have been allocated for newly added UEs.

[0047] According to this embodiment, the effect of being able to appropriately control the handover can be obtained.

[0048] Furthermore, this will enable improvements in overall service quality, such as in wireless communication systems, and will contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs): "Build resilient infrastructure, promote sustainable industrialization and foster innovation."

[0049] Although embodiments of the present invention have been described in detail above with reference to the drawings, the specific configuration is not limited to these embodiments, and design modifications and the like are also included within the scope of the gist of the present invention.

[0050] Alternatively, computer programs for realizing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the programs recorded on this recording medium may be loaded into a computer system and executed. Note that the term "computer system" here may include hardware such as an operating system and peripheral devices. Furthermore, "computer-readable recording media" refers to writable non-volatile memory such as flexible disks, magneto-optical disks, ROMs, and flash memory, portable media such as DVDs (Digital Versatile Discs), and storage devices such as hard disks built into computer systems.

[0051] Furthermore, "computer-readable recording media" also includes volatile memory (such as DRAM (Dynamic Random Access Memory)) within computer systems that act as servers or clients when programs are transmitted via networks such as the Internet or communication lines such as telephone lines, which retain programs for a certain period of time. Furthermore, the above program may be transmitted from a computer system that stores the program in a memory device or the like to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" used to transmit the program refers to a medium that has the function of transmitting information, such as a network (communication network) like the Internet or a communication line (communication line) like a telephone line. Furthermore, the above program may be intended to implement some of the functions described above. It may also be a so-called differential file (differential program) that can implement the aforementioned functions in combination with programs already recorded in the computer system. [Explanation of Symbols]

[0052] 1…Wireless access network, 10…SMO, 20…O-CU, 30…O-DU, ACC…Accelerator, AP…Access point, UE…User terminal

Claims

1. In an O-RAN specification wireless access network, a Central Unit (CU) that controls handover in its subordinate Distributed Units (DUs) is equipped with an interface for acquiring computing resource information related to the DUs. Wireless communication system.

2. The interface includes querying the computing resource information from the CU and responding to the CU with the computing resource information. The wireless communication system according to claim 1.

3. The interface includes periodic notification of the computing resource information to the CU, The wireless communication system according to claim 1.

4. A communication control method performed by a wireless communication system, In an O-RAN specification wireless access network, a Central Unit (CU) that controls handover in its subordinate Distributed Units (DUs) acquires computing resource information related to the DUs via a predetermined interface. Communication control method.

5. On the computer, In an O-RAN specification wireless access network, a Central Unit (CU) that controls handover in its subordinate Distributed Units (DUs) acquires computing resource information related to the DUs via a predetermined interface. A computer program designed to execute something.

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