Communication control device, communication control method, and computer program

Abstract

This communication control device controls a communication connection between one or a plurality of radio units (RUs) and one or a plurality of distributed units (DUs) on the basis of a switch state of a fronthaul switch between the one or plurality of RUs and the one or plurality of DUs in a wireless access network.

Description

Communication control device, communication control method, and computer program

[0001] The present invention relates to a communication control device, a communication control method, and a computer program. This application claims priority from Japanese Patent Application No. 2024-168754 filed in Japan on September 27, 2024, the content of which is incorporated herein by reference.

[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 Documents 1-4). The O-RAN specifications formulated by the O-RAN Alliance define technologies related to, for example, fronthaul.

[0003] “O-RAN A1 interface: Use Cases and Requirements 1.03”, O-RAN.WG2.A1UCR-v01.03, June 2024“O-RAN E2 Service Model (E2SM) KPM 5.0”, O-RAN.WG3.E2SM-KPM-R003-v05.00, June 2024“O-RAN Management Plane Specification 15.0”, O-RAN.WG4.MP.0-R003-v15.00, June 2024“O-RAN O1 Interface Specification 13.0”, O-RAN.WG10.O1-Interface.0-R003-v13.00, June 2024

[0004] However, in the above-described conventional O-RAN specifications, since the combination of communication between the radio unit (RU) and the distributed unit (DU) in the fronthaul is fixed to one, for example, a plurality of DUs cannot simultaneously use one RU.

[0005] This invention was made in consideration of these circumstances, and its purpose is to improve the degree of freedom in the combination of communication between RU and DU in the fronthaul.

[0006] One aspect of the present invention is a communication control device that controls the communication connection between one or more Radio Units (RUs) and one or more Distributed Units (DUs) in a wireless access network based on the switch state of a fronthaul switch between the RUs and the DUs. Another aspect of the present invention is a communication control device in which the switch state includes at least one of the following states: the switch capacity state of the fronthaul switch, the connection state of the fronthaul switch, the state of the access point cluster, and the resource consumption state of the one or more DUs. Another aspect of the present invention is a communication control device in which the number of RUs and user terminals that can be accommodated by one or more DUs is controlled based on a resource limit for the one or more DUs. Another aspect of the present invention is a communication control device in which, for RUs having multiple antenna ports among the one or more RUs, a different DU is set as the transmission destination for each antenna port.

[0007] One aspect of the present invention is a communication control method executed by a communication control device, which controls the communication connection between one or more RUs (Radio Units) and one or more DUs (Distributed Units) in a wireless access network based on the switch state of fronthaul switches between the RUs and the DUs.

[0008] One aspect of the present invention is a computer program that causes a computer to perform the step of controlling the communication connection between one or more RUs (Radio Units) and one or more DUs (Distributed Units) in a wireless access network based on the switch state of fronthaul switches between the RUs and the DUs.

[0009] According to the present invention, the degree of freedom in the communication combinations between the RU and DU in the fronthaul can be improved.

[0010] This is a block diagram showing a schematic configuration example of a wireless access network (RAN) according to one embodiment. This is a diagram showing an example of the procedure of a communication control method according to one embodiment. This is a diagram showing an example of the procedure of a communication control method according to one embodiment. This is a diagram showing an example of multicast communication in the fronthaul according to one embodiment.

[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 wireless access network (RAN) of a wireless communication system according to one embodiment. The RAN1 shown in Figure 1 conforms to the O-RAN specification. However, in this embodiment, a fronthaul interface, which is not specified in the O-RAN specification, is newly added.

[0012] RAN1 comprises a RIC (RAN Intelligent Controller) 10 (communication control device), a DU system 20, a front hall switch (FH SW) 30, and an RU 40.

[0013] RIC 10 comprises a "Non-RT RIC (Non-Real Time RAN Intelligent Controller)" 11 and a "Near-RT RIC (Near-Real Time RAN Intelligent Controller)" 12. The "Non-RT RIC" 11 provides policy information, etc., to the "Near-RT RIC" 12 via the A1 interface. The A1 interface is defined in the O-RAN specification.

[0014] The DU system 20 comprises a calculation unit 21 consisting of a CPU (Central Processing Unit) and memory, and an accelerator (ACC) 22 that realizes the functions of the DU.

[0015] The arithmetic unit 21 implements functions such as RLC (Radio Link Control) and MAC (Media Access Control).

[0016] ACC22 implements signal processing functions of the DU, such as modulation, demodulation, and encoding of digital signals. ACC22 is assigned to each user equipment (UE). In the example in Figure 1, ACC22-1 is assigned to UE#1, and ACC22-2 is assigned to UE#2.

[0017] The E2 interface is the interface between the "Near-RT RIC" 12 and the DU system 20. The E2 interface is defined in the O-RAN specification.

[0018] The O1 interface is the interface between the "Non-RT RIC" 11 and "Near-RT RIC" 12 and the DU system 20. The O1 interface is defined in the O-RAN specification.

[0019] The front haul switch 30 is located between the DU system 20 and the RU 40. In the example shown in Figure 1, the front haul switch 30 is located between the DU system 20 and five RU 40s (RU 40-1, 40-2, 40-3, 40-4, 40-5). UE#1 can wirelessly connect to three RU 40s: 1, 40-2, and 40-3. UE#2 can wirelessly connect to three RU 40s: 3, 40-4, and 40-5.

[0020] The front-haul switch 30 switches communication between each ACC 22 and each RU 40 in the DU system 20. The front-haul switch 30 establishes the communication connection between each ACC 22 and each RU 40 in the DU system 20.

[0021] The fronthaul switch 30 can provide multicast communication in addition to unicast communication. For example, if RU40-3 specifies the addresses of ACC22-1 and ACC22-2 as multicast addresses, the fronthaul switch 30 transmits the radio signal received from RU40-3 to both ACC22-1 and ACC22-2.

[0022] In this embodiment, multiple DUs can share a single RU in an O-RAN specification wireless access network. To this end, the O-RAN specification wireless access network is provided with a first interface that notifies the single RU of multicast information specifying multicast communication between the single RU and multiple DUs. In this embodiment, the first interface is the interface of the fronthaul Management Plane (M-Plane). Specifically, the signaling message of the fronthaul Management Plane includes multicast information (hereinafter simply referred to as multicast information) specifying multicast communication between the single RU and multiple DUs. An example of multicast information is described below.

[0023] (Example of Multicast Information 1) Multicast information is information that includes address information of multiple DUs that are destinations for multicast communication. In the example in Figure 1, when the DU implemented by ACC22-1 assigned to UE#1 (hereinafter referred to as DU#1) and the DU implemented by ACC22-2 assigned to UE#2 (hereinafter referred to as DU#2) share a single RU40-3 that both UE#1 and #2 can wirelessly connect to, the addresses #1 of DU#1 (ACC22-1) and #2 of DU#2 (ACC22-2) are notified to the RU40-3 as multicast information. As a result, by specifying the addresses #1 of DU#1 and #2 of DU#2 as multicast addresses, the wireless signals transmitted by the RU40-3 are received by both DU#1 and DU#2 via the fronthaul switch 30. This allows DU#1 and DU#2 to share a single RU40-3, which can be wirelessly connected to both UE#1 and UE#2.

[0024] (Example of Multicast Information 2) Multicast information includes resource block information that indicates the resource block (RB) to be used for multicast communication. In the example in Figure 1, when DU#1 and #2 share a single RU40-3 that UE#1 and #2 can wirelessly connect to, DU#1 and #2 notify RU40-3 of RB information #1 indicating RB#1 to be used between DU#1 and UE#1, and RB information #1 indicating RB#2 to be used between DU#2 and UE#2, as multicast information. As a result, RU40-3 designates RB#1 for DU#1 and UE#1 and RB#2 for DU#2 and UE#2 as the RBs to be used for multicast communication, so that the wireless signals of RB#1 and #2 transmitted by RU40-3 are received by both DU#1 and DU#2 via the fronthaul switch 30. This allows DU#1 and DU#2 to share a single RU40-3, which can be wirelessly connected to both UE#1 and UE#2.

[0025] (Example 3 of Multicast Information) Multicast information is information that includes resource element information indicating the resource elements (REs) that are the target of multicast communication. In the example in Figure 1, when DU#1 and #2 share a single RU40-3 that both UE#1 and #2 can wirelessly connect to, they notify RU40-3 of RE information #1 indicating RE#1 to be used between DU#1 and UE#1 and RE information #1 indicating RE#2 to be used between DU#2 and UE#2 as multicast information. As a result, RU40-3 specifies RE#1 for DU#1 and UE#1 and RE#2 for DU#2 and UE#2 as the REs that are the target of multicast communication, so that the wireless signals of RE#1 and #2 transmitted by RU40-3 are received by both DU#1 and DU#2 via the fronthaul switch 30. This allows DU#1 and DU#2 to share a single RU40-3 that can be wirelessly connected to both UE#1 and UE#2. In example 3 of the multicast information, only the RE of the channel estimation reference signal for inter-DU cooperation can be multicast using RE information that indicates the RE to be targeted for multicast communication.

[0026] The above is an explanation of an example of multicast information.

[0027] In this embodiment, a second interface is provided for notifying policy information regarding multicast communication from the "Non-RT RIC" 11 to the "Near-RT RIC" 12. In this embodiment, the second interface is included in the A1 interface between the "Non-RT RIC" 11 and the "Near-RT RIC" 12. An example of policy information regarding multicast communication (hereinafter simply referred to as policy information) is described below.

[0028] (Example of policy information 1) Policy information is policy information regarding multicast communication, which is determined according to the number of UEs that can be accommodated for a single RU. Specifically, the DU (ACC22), RB, RE, etc. that will be subject to multicast communication are determined according to the number of UEs that can be accommodated for a single RU that will be subject to multicast communication.

[0029] (Example of policy information 2) The policy information is a policy information regarding multicast communication that is determined according to the number of RUs that can accommodate multiple DUs. Specifically, the DUs (ACC22), RBs, REs, etc. that will be targeted for multicast communication are determined according to the number of RUs that can accommodate multiple DUs that are the target of multicast communication.

[0030] (Example of policy information 3) Policy information is policy information regarding multicast communication that is determined according to the services used by the UEs that a particular RU accommodates. Specifically, the DUs (ACC22), RBs, REs, etc. that are subject to multicast communication are determined according to the services used by the UEs that a particular RU accommodates that are subject to multicast communication.

[0031] The above is an explanation of an example of policy information.

[0032] Figures 2 and 3 show examples of the procedure for the communication control method according to this embodiment.

[0033] Figure 2 shows an example of a communication control procedure when a DU in the DU system 20 is a client. Referring to Figure 2, an example of a communication control procedure when a DU in the DU system 20 is a client will be explained.

[0034] (Step S1) Each DU (ACC22) notifies RIC10 of its own UE capacity and cell capacity.

[0035] (Step S2) RIC 10 calculates the RU signal, PRB (Physical RB), RE, etc. to be used for multicast communication, subject to the switch (SW) capacity limitations of the front hall switch (FHSW) 30.

[0036] (Step S3) Based on the calculation results of step S2, RIC10 notifies each DU (ACC22) of multicast information (DU,RU address assignment and duplicate information). This multicast information includes the address information of the RU targeted by multicast communication and the address information of multiple DUs, RB information indicating the RB targeted by multicast communication, RE information indicating the RE targeted by multicast communication, etc. In step S3, the multicast information is notified to each DU (ACC22) using the A1 interface, O1 interface, E2 interface, etc.

[0037] (Step S4) Each DU (ACC22) notifies one of the target RUs 40 of the multicast communication of multicast information based on the multicast information notified in step S3 (RU address assignment and duplicate information). This multicast information includes address information of multiple DUs that are destinations for the multicast communication, RB information indicating the target RB of the multicast communication, RE information indicating the target RE of the multicast communication, etc. In step S4, the multicast information is notified to one of the target RUs 40 of the multicast communication using the fronthaul management plane interface.

[0038] (Step S5) Multicast communication is initiated using a combination of multiple DUs (ACC22) and one RU40 specified in the multicast information of Step S3.

[0039] (Step S6) RIC10 calculates access point (AP) clusters and interference clusters according to the connections between multiple DUs (ACC22) and one RU40 related to multicast communication.

[0040] (Step S7) Based on the calculation results of the AP cluster and interference cluster in step S6, RIC10 notifies each DU (ACC22) of the AP cluster and interference cluster (cluster indication).

[0041] (Step S8) In the combination of multiple DUs (ACC22) and one RU40 in which multicast communication has been initiated, radio signal processing is started in the AP cluster and interference cluster specified in step S7.

[0042] Figure 3 is a diagram illustrating an example of a communication control procedure when the client is outside the DU system 20. Referring to Figure 3, an example of a communication control procedure when the client is outside the DU system 20 will be explained. In Figure 3, the same reference numerals are used for the steps corresponding to each step in Figure 2, and their explanations are omitted.

[0043] In Figure 3, steps S1 to S3 are executed. Steps S1 to S3 are the same as in Figure 2 described above. Next, step S4a is executed.

[0044] (Step S4a) The "Netconf client (SMO (Service and Management Orchestration))" (not shown) of the wireless communication system notifies the multicast information to one RU40 that is the target of multicast communication based on the multicast information notified to each DU (ACC22) in Step S3 (RU address assignment and Duplicate information). This multicast information includes the address information of a plurality of DUs that are the destinations of multicast communication, RB information indicating the RB that is the target of multicast communication, RE information indicating the RE that is the target of multicast communication, and the like. In Step S4a, the multicast information is notified to one RU40 that is the target of multicast communication using the interface of the front haul management plane.

[0045] Next, Steps S5 to S8 are executed. Steps S5 to S8 are the same as those in FIG. 2 described above.

[0046] According to this embodiment, in the O-RAN specification wireless access network, a plurality of DUs can share one RU. As a result, for example, the same RU can be used between UEs that use different DUs, so the same AP cluster can be shared between the different DUs.

[0047] FIG. 4 is a diagram showing an example of multicast communication in the front haul according to this embodiment. As illustrated in FIG. 4, one RU40-3 to which both UEs #1 and #2 can be wirelessly connected, DU #1 (ACC22-1) assigned to UE #1, and DU #2 (ACC22-2) assigned to UE #2 perform multicast communication. By this multicast communication, the wireless signal 100 transmitted by RU40-3 is replicated by the front haul switch 30, and the replicated wireless signals 100-1 and 100-2 are received by DUs #1 and #2, respectively. As a result, DUs #1 and #2 can share one RU40-3 to which both UEs #1 and #2 can be wirelessly connected.

[0048] In the wireless access network according to this embodiment, the range and radio quality of the AP cluster that can be formed for the UE change depending on which RU40 communicates and connects with which DU (ACC22) and which RB or RE signals are multicast. On the other hand, there are limitations on the switch capacity of the front haul switch 30 that provides multicast communication due to hardware and the like. Therefore, it is necessary to calculate RU signals, RBs, REs, etc. to be the targets of multicast communication under the limitation of the switch capacity of the front haul switch 30.

[0049] For this reason, in this embodiment, the RIC10 (communication control device) controls the communication connection between the one or more RUs 40 and the one or more DUs (ACC22) based on the switch state of the front haul switch 30 between the one or more RUs 40 and the one or more DUs (ACC22) in the wireless access network.

[0050] The switch state includes at least one state among the switch capacity state of the front haul switch 30, the connection state of the front haul switch 30, the state of the AP cluster, and the resource consumption state of the one or more DUs (ACC22). The switch state is notified from the DU system 20 to the RIC10.

[0051] The RIC10 may control the number of RUs and UEs that can be accommodated for the one or more DUs based on the resource upper limit for the one or more DUs (ACC22).

[0052] The RIC10 may set different DUs (ACC22) as transmission destinations for each antenna port for the RU40 having a plurality of RF (Radio Frequency) chains (antenna ports) among the one or more RUs 40.

[0053] According to this embodiment, appropriate traffic management of wireless signals can be performed based on the switch capacity, connection state, etc. of the front haul switch 30.

[0054] According to the above-described embodiment, an effect of improving the degree of freedom in the combination of communication between the RU and the DU in the front haul can be obtained.

[0055] 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."

[0056] 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.

[0057] For example, although the above-described embodiment was applied to a wireless access network conforming to the O-RAN specification, it may also be applied to wireless access networks other than those conforming to the O-RAN specification.

[0058] 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. The term "computer system" here may include hardware such as an operating system and peripheral devices. Furthermore, "computer-readable recording medium" 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 a computer system.

[0059] Furthermore, "computer-readable recording media" includes volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that acts as a server or client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which retains the program for a certain period of time. In addition, the above program may be transmitted from the computer system that stores the program in a storage device, etc., to another computer system via a transmission medium or by transmission waves within the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium that has the function of transmitting information, such as a network such as the Internet or a communication line such as a telephone line. Furthermore, the above program may be for the purpose of realizing a part of the above-mentioned functions. In addition, it may be a so-called differential file (differential program) that can realize the above-mentioned functions in combination with a program already recorded in the computer system.

[0060] According to the present invention, it is possible to improve the degree of freedom in the combination of communication between the RU and DU in the fronthaul.

[0061] 1...Wireless access network, 10...RIC (Communication Control Unit), 11...Non-RT RIC, 12...Near-RT RIC, 20...DU system, 21...Calculation unit, 22...Accelerator (ACC), 30...Fronthaul switch, 40...RU

Claims

1. A communication control device that controls the communication connection between one or more Radio Units (RUs) and one or more Distributed Units (DUs) in a wireless access network based on the switch state of front-haul switches between the RUs and the DUs.

2. The communication control device according to claim 1, wherein the switch state includes at least one state among the switch capacity state of the fronthaul switch, the connection state of the fronthaul switch, the state of the access point cluster, and the resource consumption state of the one or more DUs.

3. A communication control device according to claim 1, which controls the number of RUs and user terminals that can be accommodated for one or more DUs based on the resource limits for one or more DUs.

4. The communication control device according to claim 1, wherein for one or more RUs having multiple antenna ports, a different DU is set as the transmission destination for each antenna port.

5. A communication control method executed by a communication control device, which controls the communication connection between one or more RUs (Radio Units) and one or more DUs (Distributed Units) in a wireless access network based on the switch state of front-haul switches between the RUs and the one or more DUs.

6. A computer program that causes a computer to perform the step of controlling the communication connection between one or more RUs (Radio Units) and one or more DUs (Distributed Units) in a wireless access network based on the switch state of front-haul switches between the RUs and the DUs.

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