Wireless communication system, communication control method, and computer program

Abstract

This wireless communication system includes a first interface for notifying one radio unit (RU) of multicast information designating multicast communication between the one RU and a plurality of distributed units (DUs) in an O-RAN specification wireless access network.

Description

Wireless Communication System, Communication Control Method, and Computer Program

[0001] The present invention relates to a wireless communication system, a communication control method, and a computer program. This application claims priority to Japanese Patent Application No. 2024-168753 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 established 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 wireless communication system in an O-RAN specification wireless access network, comprising a first interface that notifies a single Radio Unit (RU) of multicast information specifying multicast communication between the RU and a plurality of Distributed Units (DUs). One aspect of the present invention is a wireless communication system in which the first interface is an interface of the fronthaul management plane. One aspect of the present invention is a wireless communication system in which the multicast information includes address information of a plurality of DUs that are the destination of the multicast communication. One aspect of the present invention is a wireless communication system in which the multicast information includes resource block information indicating the target resource block of the multicast communication. One aspect of the present invention is a wireless communication system in which the multicast information includes resource element information indicating the target resource element of the multicast communication. One aspect of the present invention is a wireless communication system in which the multicast information further comprises a second interface that notifies a "Non-RT RIC" of policy information relating to the multicast communication from a "Near-RT RIC". One aspect of the present invention is a wireless communication system in which the second interface is included in the A1 interface between "Non-RT RIC" and "Near-RT RIC". One aspect of the present invention is a wireless communication system in which the policy information is determined according to the number of user terminals accommodated for the one RU. One aspect of the present invention is a wireless communication system in which the policy information is determined according to the number of RUs accommodated for the plurality of DUs. One aspect of the present invention is a wireless communication system in which the policy information is determined according to the services used by the user terminals accommodated for the one RU.One aspect of the present invention is a wireless communication system in which the policy information is determined according to an Access Point (AP) cluster determined for each user. Another aspect of the present invention is a wireless communication system in which the policy information indicates the range of Access Points (APs) that perform channel estimation, determined for each user.

[0007] One aspect of the present invention is a communication control method performed by a wireless communication system, wherein multicast information specifying multicast communication between one RU (Radio Unit) and multiple DUs (Distributed Units) in an O-RAN specification wireless access network is notified to the one RU via a predetermined interface.

[0008] One aspect of the present invention is a computer program that causes a computer to perform the step of notifying a single Radio Unit (RU) via a predetermined interface of multicast information specifying multicast communication between a single RU and a plurality of Distributed Units (DUs) in an O-RAN specification wireless access network.

[0009] According to the present invention, the advantage is that the degree of freedom in the communication combination 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] (Example of policy information 4) Policy information is policy information regarding multicast communication that is determined according to the Access Point (AP) cluster determined for each user (UE).

[0032] (Example of policy information 5) Policy information is information that indicates the range of APs that perform channel estimation, which is determined for each user (UE).

[0033] The above is an explanation of an example of policy information.

[0034] Figures 2 and 3 show examples of the procedure for the communication control method according to this embodiment.

[0035] 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.

[0036] (Step S1) Each DU (ACC22) notifies RIC10 of its own UE capacity and cell capacity.

[0037] (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.

[0038] (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 for multicast communication and the address information of multiple DUs, RB information indicating the RB targeted for multicast communication, RE information indicating the RE targeted for multicast communication, etc. In step S3, the multicast information is notified to each DU (ACC22) using the A1 interface, O1 interface, E2 interface, etc.

[0039] (Step S4) Each DU (ACC22) notifies the multicast information to one RU40 that is the target of multicast communication based on the multicast information notified 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 the multicast communication, RB information indicating the RB that is the target of the multicast communication, RE information indicating the RE that is the target of the multicast communication, and the like. In Step S4, the multicast information is notified to one RU40 that is the target of multicast communication using the interface of the front hole management plane.

[0040] (Step S5) Multicast communication is started with the combination of a plurality of DUs (ACC22) specified by the multicast information in Step S3 and one RU40.

[0041] (Step S6) The RIC10 calculates an access point (AP) cluster and an interference cluster according to the connection between a plurality of DUs (ACC22) related to the multicast communication and one RU40.

[0042] (Step S7) The RIC10 notifies each DU (ACC22) of the AP cluster and the interference cluster based on the calculation results of the AP cluster and the interference cluster in Step S6 (cluster indication).

[0043] (Step S8) In the combination of a plurality of DUs (ACC22) in which the multicast communication has been started and one RU40, radio signal processing in the AP cluster and the interference cluster specified in Step S7 is started.

[0044] Figure 3 is a diagram showing an example of the procedure of the communication control method when the client is outside the DU system 20. Referring to Figure 3, an example of the procedure of the communication control method when the client is outside the DU system 20 will be described. In Figure 3, the steps corresponding to each step in Figure 2 are denoted by the same reference numerals, and the description thereof is omitted.

[0045] In FIG. 3, steps S1 to S3 are executed. Steps S1 to S3 are the same as those in FIG. 2 described above. Then, step S4a is executed.

[0046] (Step S4a) The "Netconf client (SMO (Service and Management Orchestration))" (not shown) of the wireless communication system notifies one RU40 targeted for multicast communication of the multicast information (RU address assignment and Duplicate information) based on the multicast information notified to each DU (ACC22) in step S3. This multicast information includes the address information of a plurality of DUs that are destinations of the multicast communication, RB information indicating the RB targeted for the multicast communication, RE information indicating the RE targeted for the multicast communication, and the like. In step S4a, the multicast information is notified to one RU40 targeted for multicast communication using the interface of the front hole management plane.

[0047] Then, steps S5 to S8 are executed. Steps S5 to S8 are the same as those in FIG. 2 described above.

[0048] According to this embodiment, in an O-RAN specification wireless access network, a plurality of DUs can share one RU. Thereby, for example, since the same RU can be used between UEs using different DUs, the same AP cluster can be shared between the different DUs.

[0049] Figure 4 shows an example of multicast communication in the fronthaul according to this embodiment. As illustrated in Figure 4, a single RU40-3, which can be wirelessly connected to both UE#1 and #2, and DU#1 (ACC22-1) assigned to UE#1 and DU#2 (ACC22-2) assigned to UE#2 perform multicast communication. Through this multicast communication, the wireless signal 100 transmitted by RU40-3 is duplicated by the fronthaul switch 30, and the duplicated wireless signals 100-1 and 100-2 are received by DU#1 and #2, respectively. As a result, DU#1 and DU#2 can share a single RU40-3, which can be wirelessly connected to both UE#1 and #2.

[0050] In the wireless access network according to this embodiment, the range of AP clusters that can be formed for the UE changes depending on which RU 40 communicates with which DU (ACC 22) and which RB and RE signals are multicast. On the other hand, the switching capacity of the fronthaul switch 30 that provides multicast communication is limited by hardware and other factors. Therefore, it is necessary to calculate the RU signals, RBs, REs, etc. that will be targeted for multicast communication under the limitations of the switching capacity of the fronthaul switch 30.

[0051] Therefore, in this embodiment, the RIC 10 (communication control device) controls the communication connection between one or more RU 40 and one or more DU (ACC 22) in the wireless access network based on the switch state of the fronthaul switch 30 between one or more RU 40 and one or more DU (ACC 22).

[0052] The switch status includes at least one of the following: the switch capacity status of the fronthaul switch 30, the connection status of the fronthaul switch 30, the status of the AP cluster, and the resource consumption status of one or more DUs (ACC 22). The switch status is notified from the DU system 20 to the RIC 10.

[0053] RIC10 may control the number of RUs and UEs that can be accommodated for one or more DUs (ACC22) based on the resource limit for said DU.

[0054] RIC10 may set a different DU (ACC22) as the transmission destination for each antenna port of one or more RU40 that have multiple RF (Radio Frequency) chains (antenna ports).

[0055] According to this embodiment, appropriate wireless signal traffic management can be performed based on the switch capacity and connection status of the front haul switch 30.

[0056] According to the above-described embodiment, the effect is obtained to improve the degree of freedom in the combination of communication between the RU and DU in the fronthaul.

[0057] 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."

[0058] 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.

[0059] 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.

[0060] 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.

[0061] 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.

[0062] 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.

[0063] 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 wireless communication system in an O-RAN specification wireless access network, comprising a first interface that notifies a single Radio Unit (RU) of multicast information specifying multicast communication between the RU and multiple Distributed Units (DUs).

2. The wireless communication system according to claim 1, wherein the first interface is an interface for the fronthaul management plane.

3. The wireless communication system according to claim 1, wherein the multicast information includes address information of a plurality of DUs that are destinations for multicast communication.

4. The wireless communication system according to claim 1, wherein the multicast information includes resource block information indicating a resource block that is the target of multicast communication.

5. The wireless communication system according to claim 1, wherein the multicast information includes resource element information indicating resource elements that are the target of multicast communication.

6. The wireless communication system according to claim 1, further comprising a second interface for notifying policy information relating to multicast communication from a "Non-RT RIC" to a "Near-RT RIC".

7. The wireless communication system according to claim 6, wherein the second interface is included in the A1 interface between the "Non-RT RIC" and the "Near-RT RIC".

8. The wireless communication system according to claim 6, wherein the policy information is determined according to the number of user terminals that can be accommodated with respect to one RU.

9. The wireless communication system according to claim 6, wherein the policy information is determined according to the number of RUs that can be accommodated for the plurality of DUs.

10. The wireless communication system according to claim 6, wherein the policy information is determined according to the services used by the user terminals accommodated by the first RU.

11. The wireless communication system according to claim 6, wherein the policy information is determined according to the AP (Access Point) cluster determined for each user.

12. The wireless communication system according to claim 6, wherein the policy information indicates the range of Access Points (APs) that perform channel estimation determined for each user.

13. A communication control method performed by a wireless communication system, wherein, in an O-RAN specification wireless access network, multicast information specifying multicast communication between one RU (Radio Unit) and multiple DUs (Distributed Units) is notified to the one RU via a predetermined interface.

14. A computer program that causes a computer to perform the step of notifying a single RU (Radio Unit) via a predetermined interface of multicast information specifying multicast communication between a single RU and multiple DUs (Distributed Units) in an O-RAN specification wireless access network.

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