Wireless communication system, communication control method, and computer program

Abstract

To improve the flexibility of communication combinations between RU and DU in the front haul. [Solution] The wireless communication system includes a first interface that notifies a single RU (Radio Unit) of multicast information specifying multicast communication between a single RU and multiple DUs (Distributed Units) in an O-RAN specification wireless access network.

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

Prior Art Documents

Non-Patent Documents

[0003]

Non-Patent Document 1

Non-Patent Document 2

Non-Patent Document 3

Non-Patent Document 4

Summary of the Invention

[0004] However, in the conventional O-RAN specification mentioned above, the communication combination between the RU (Radio Unit) and DU (Distributed Unit) in the fronthaul is fixed to one, meaning that, for example, multiple DUs cannot use the same RU simultaneously.

[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 RUs and DUs in the fronthaul. [Means for solving the problem]

[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 RU (Radio Unit) of multicast information specifying multicast communication between a single RU and a plurality of DUs (Distributed Units). One aspect of the present invention is a wireless communication system in which the first interface is an interface to 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 destinations for multicast communication. One aspect of the present invention is a wireless communication system in which the multicast information includes resource block information indicating a resource block that is the target of multicast communication. One aspect of the present invention is a wireless communication system in which the multicast information includes resource element information indicating resource elements that are the target of multicast communication. One aspect of the present invention is a wireless communication system further comprising a second interface for notifying policy information relating to multicast communication from a "Non-RT RIC" to 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 the "Non-RT RIC" and the "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 that can be accommodated for 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 that can be 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 by the first RU. One aspect of the present invention is a wireless communication system in which the policy information is determined according to the AP (Access Point) cluster determined for each user. One aspect of the present invention is a wireless communication system in which the policy information indicates the range of APs (Access Points) 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 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 RU (Radio Unit) via a predetermined interface of multicast information specifying multicast communication between a single RU and a plurality of DUs (Distributed Units) in an O-RAN specification wireless access network. [Effects of the Invention]

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

[0010] [Figure 1] This is a block diagram showing a schematic configuration example of a wireless access network (RAN) according to one embodiment. [Figure 2] This figure shows an example of the procedure for a communication control method according to one embodiment. [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 multicast communication in a fronthaul 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 illustrating 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 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 an RIC (RAN Intelligent Controller) 10 (communication control device), a DU system 20, a front hall switch (FH SW) 30, and an RU 40.

[0013] RIC10 includes 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 and the like to the "Near-RT RIC" 12 via the A1 interface. The A1 interface is defined by the O-RAN specification.

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

[0015] The computing unit 21 realizes functions such as, for example, RLC (Radio Link Control) and MAC (Media Access Control).

[0016] The ACC 22 realizes signal processing functions such as, for example, modulation / demodulation and encoding of digital signals, which are functions of the DU. The ACC 22 is assigned for each user equipment (UE). In the example of FIG. 1, the ACC 22-1 is assigned to UE#1, and the ACC 22-2 is assigned to UE#2.

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

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

[0019] The front haul switch 30 is located between the DU system 20 and the RU40. In the example shown in Figure 1, the front haul switch 30 is located between the DU system 20 and five RU40s (RU40-1, 40-2, 40-3, 40-4, 40-5). UE#1 can wirelessly connect to three RU40s: 1, 40-2, and 40-3. UE#2 can wirelessly connect to three RU40s: 3, 40-4, and 40-5.

[0020] The front-haul switch 30 switches the communication between each ACC22 and each RU40 in the DU system 20. The front-haul switch 30 establishes the communication connection between each ACC22 and each RU40 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 will transmit 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 1 of multicast information) Multicast information is information that includes address information for multiple DUs (Device Undergrounds) that are destinations for multicast communication. In the example in Figure 1, when DU #1 (hereinafter referred to as DU#1) implemented by ACC22-1 assigned to UE#1 and DU #2 (hereinafter referred to as DU#2) implemented by ACC22-2 assigned to UE#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 address #1 of DU#1 and address #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 that both UE#1 and #2 can wirelessly connect to.

[0024] (Example 2 of multicast information) 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 both UE#1 and #2 can wirelessly connect to, RU40-3 is notified 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 specifies 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 that both UE#1 and #2 can wirelessly connect to.

[0025] (Example 3 of multicast information) Multicast information includes resource element information that indicates the resource element (RE) to be used for 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, the multicast information includes 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, which are notified to the RU40-3. As a result, the RU40-3 specifies RE#1 for DU#1 and UE#1 and RE#2 for DU#2 and UE#2 as the REs to be used for multicast communication, so that the wireless signals of RE#1 and #2 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 that both UE#1 and #2 can wirelessly connect to. In Example 3 of multicast information, only the RE of the reference signal used for channel estimation for inter-DU cooperation can be multicast using RE information that indicates the RE of the target of 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 a policy information regarding multicast communication that is determined according to the number of UEs (User Entities) that can accommodate a single RU (Ruler). Specifically, the DU (ACC22), RB (Remote Access), RE (Remote Access) and other targets for multicast communication are determined according to the number of UEs that can accommodate a single RU that is the target of multicast communication.

[0029] (Example of policy information 2) Policy information is a policy information regarding multicast communication that is determined according to the number of RUs (Ruler Units) that can accommodate multiple DUs (Units of Communication). Specifically, the DUs (ACC22), RBs, REs, etc. that are subject to 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 a policy information regarding multicast communication that is determined according to the services used by the UEs that a particular RU accommodates. Specifically, the DU (ACC22), RB, RE, etc. that are subject to multicast communication are determined according to the services used by the UEs that accommodate the RU that are subject to multicast communication.

[0031] (Example of policy information 4) Policy information is determined for each user (UE) according to their Access Point (AP) cluster and concerns multicast communication policies.

[0032] (Example of policy information 5) Policy information indicates the scope of the application platform (AP) that performs 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) RIC10 calculates the RU signal, PRB (Physical RB), RE, etc. to be used for multicast communication, under the limitations of the switch (SW) capacity 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, and RE information indicating the RE targeted for multicast communication. 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 one of the target RU40s 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 of the multicast communication, RB information indicating the target RB of the multicast communication, and RE information indicating the target RE of the multicast communication. In step S4, the multicast information is notified to one of the target RU40s of the multicast communication using the fronthaul management plane interface.

[0040] (Step S5) Multicast communication is initiated using the combination of multiple DUs (ACC22s) and one RU40 specified in the multicast information of Step S3.

[0041] (Step S6) RIC10 calculates access point (AP) clusters and interference clusters according to the connections between multiple DUs (ACC22) and one RU40 for multicast communication.

[0042] (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).

[0043] (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.

[0044] Figure 3 shows 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.

[0045] 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.

[0046] (Step S4a) The "Netconf client (SMO (Service and Management Orchestration))" (not shown) of the wireless communication system notifies one of the target RU40s of the 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 address information of multiple DUs that are destinations for the multicast communication, RB information indicating the target RB of the multicast communication, and RE information indicating the target RE of the multicast communication. In step S4a, the multicast information is notified to one of the target RU40s of the multicast communication using the fronthaul management plane interface.

[0047] Next, steps S5 through S8 are executed. Steps S5 through S8 are the same as in Figure 2 above.

[0048] According to this embodiment, multiple DUs can share a single RU in an O-RAN-compliant wireless access network. This allows, for example, UEs using different DUs to utilize the same RU, and thus the same AP cluster can be shared among those 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. This allows DU#1 and DU#2 to 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 and the wireless quality change depending on which RU40 communicates with which DU (ACC22) 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 RIC10 (communication control device) controls the communication connection between one or more RU40s and one or more DUs (ACC22s) in the wireless access network based on the switch state of the fronthaul switch 30 between one or more RU40s and one or more DUs (ACC22s).

[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 (ACC22). The switch status is notified from the DU system 20 to the RIC10.

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

[0054] RIC10 may set a different DU (ACC22) as the transmission destination for each antenna port of one or more RU40s 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 embodiment described above, the effect is 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, the embodiment described above was applied to a wireless access network conforming to the O-RAN specification, but 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. 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.

[0061] 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]

[0062] 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…Front hall switch, 40…RU

Claims

1. In an O-RAN specification wireless access network, a first interface is provided that notifies the one RU (Radio Unit) of multicast information specifying multicast communication between one RU and multiple DUs (Distributed Units). Wireless communication system.

2. The first interface is the interface of the fronthaul management plane. The wireless communication system according to claim 1.

3. The multicast information includes address information of multiple DUs that are destinations for multicast communications. The wireless communication system according to claim 1.

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

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

6. It further includes a second interface for notifying policy information regarding the aforementioned multicast communication from the "Non-RT RIC" to the "Near-RT RIC," The wireless communication system according to claim 1.

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

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

9. The policy information is determined according to the number of RUs that can accommodate the plurality of DUs. The wireless communication system according to claim 6.

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

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

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

13. A communication control method performed by a wireless communication system, 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. Communication control method.

14. On the computer, In an O-RAN specification wireless access network, the steps include notifying the one RU (Radio Unit) via a predetermined interface of multicast information specifying multicast communication between one RU and multiple DUs (Distributed Units), A computer program designed to execute something.

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