Wireless communication system, communication control method, and computer program

Abstract

A wireless communication system, according to the present invention, comprises an interface for a communication control device, which controls the communication connection between a radio unit (RU) and a distributed unit (DU) in a wireless access network compliant with O-RAN specifications, to acquire the round-trip time between a to-be-measured target DU and an RU.

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 from Japanese Patent Application No. 2024-169180 filed in Japan on September 27, 2024, and incorporates its content herein by reference.

[0002] By the O-RAN (Open Radio Access Network) Alliance, the opening and intelligentization of next-generation radio access networks (RANs) such as the 5th generation (5G) mobile communication system are being considered (see, for example, Non-Patent Documents 1-4). In the O-RAN specifications formulated by the O-RAN Alliance, for example, technologies related to fronthaul are defined.

[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, when changing the communication connection between the RU (Radio Unit) and the DU (Distributed Unit) in the fronthaul, it was not possible to determine whether the RU and the DU satisfy the delay constraint between the RU and the DU in the fronthaul. For this reason, it may have been difficult to appropriately change the communication connection between the RU and the DU in the fronthaul.

[0005] This invention has been made in consideration of these circumstances, and its purpose is to appropriately modify the communication connection between the RU and DU in the front haul.

[0006] One aspect of the present invention is a wireless communication system in which a communication control device that controls the communication connection between a Radio Unit (RU) and a Distributed Unit (DU) in an O-RAN specification wireless access network has an interface for acquiring the round trip time between the DU to be measured and the RU. Another aspect of the present invention is a wireless communication system in which the interface includes a round trip time measurement instruction from the communication control device to the DU to be measured and a round trip time response from the DU to be measured to the communication control device. Another aspect of the present invention is a wireless communication system in which the interface includes notification from the DU to be measured to the communication control device of a combination of RU and DU that satisfies delay constraints between the RU and DU in the fronthaul. Another aspect of the present invention is a wireless communication system in which the RU and the DU can communicate with each other via the same fronthaul network domain. One aspect of the present invention is a wireless communication system in which the interface includes obtaining the round trip time via an A1 interface between a "Non-RT RIC" and a "Near-RT RIC". Another aspect of the present invention is a wireless communication system in which the interface includes obtaining the round trip time via an E2 interface between a DU and a "Near-RT RIC". Another aspect of the present invention is a wireless communication system in which the interface includes obtaining the round trip time via an O1 interface between a DU and a "Non-RT RIC".

[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 communication control device that controls the communication connection between a Radio Unit (RU) and a Distributed Unit (DU) via a predetermined interface acquires the round-trip time between the DU and the RU to be measured.

[0008] One aspect of the present invention is a computer program that causes a computer to perform the step of obtaining the round-trip time between a DU and a RU to be measured, which is controlled by a communication control device that controls the communication connection between a RU (Radio Unit) and a DU (Distributed Unit) via a predetermined interface in an O-RAN specification wireless access network.

[0009] According to the present invention, the effect is obtained that the communication connection between the RU and DU in the fronthaul can be appropriately modified.

[0010] This is a block diagram showing a schematic configuration example of a wireless access network of a wireless communication system according to one embodiment. This is a diagram showing an example of a procedure for a communication control method according to one embodiment. This is a diagram showing an example of vDU scaling control in 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), vDUs (virtual DUs) 20 (20-1, 20-2) located in the central office building 200 (200-1, 200-2), a fronthaul network domain 30, and RUs 40 (40-1, 40-2, 40-3, 40-4, 40-5, 40-6).

[0013] RIC10 and the central office 200 are configured to communicate via a communication line. The central office 200 and the RU40 are configured to communicate via a front-haul network domain 30. The front-haul network domain 30 is, for example, an Ethernet (registered trademark) domain.

[0014] RIC10 controls the communication connection between the RU and DU in an O-RAN specification wireless access network.

[0015] The vDU20 implements the signal processing functions of the DU, such as modulation, demodulation, and encoding of digital signals. The vDU20 is implemented by computer hardware such as a CPU (Central Processing Unit) and memory installed in its own station building 200.

[0016] In the example in Figure 1, two stations 200-1 and 200-2 are shown. Stations 200-1 and 200-2 are located in different places. Therefore, the communication delay between a single RU 40, for example RU40-1, and a vDU 20-2 station 200-2 may differ. For this reason, even if the RU40-1 is the same, even if one vDU 20-1 satisfies the delay constraint between the RU and DU in the fronthaul, the other vDU 20-2 may not necessarily satisfy the same delay constraint.

[0017] In this embodiment, the aim is to determine in RAN1 whether a combination of RU40 and vDU20 satisfies the delay constraint between RU and DU in the fronthaul. In particular, the aim is to determine whether a combination of RU40 and vDU20 that can communicate via the fronthaul network domain 30 satisfies the said delay constraint.

[0018] Therefore, in this embodiment, the RIC 10 is provided with an interface (hereinafter referred to as the first interface for convenience of explanation) for acquiring the RTT (Round Trip Time) between the vDU 20 and RU 40 to be measured.

[0019] The RIC 10 shown in Figure 1 comprises an acquisition unit 11, a determination unit 12, and a control unit 13 as its functional units. The RIC 10 includes a "Non-RT RIC (Non-Real Time RAN Intelligent Controller)" (not shown) and a "Near-RT RIC (Near-Real Time RAN Intelligent Controller)" (not shown), and the functions of the RIC 10 are realized by the "Non-RT RIC" and the "Near-RT RIC".

[0020] The acquisition unit 11 acquires the RTT between RU40 and vDU20 via the first interface.

[0021] The determination unit 12 determines, based on the RTT between RU 40 and vDU 20, a combination of RU and DU that satisfies the delay constraint between RU and DU in the fronthaul. Hereinafter, the delay constraint between RU and DU in the fronthaul may be referred to as the FH delay constraint.

[0022] The control unit 13 controls the communication connection between the RU 40 and the vDU 20 based on the determination result of the determination unit 12's determination of a combination of RU and DU that satisfies the FH delay constraint.

[0023] Figure 2 is a diagram showing an example of the procedure of the communication control method according to this embodiment. The communication control method according to this embodiment will be described with reference to Figure 2.

[0024] (Step S1) The acquisition unit 11 of the RIC 10, via the first interface, instructs the vDU 20 to be measured to measure the RTT between the vDU 20 and the RU 40 (instruction to measure RTT between DU and RU).

[0025] The RTT measurement instruction between the DU and RU in the first interface may be newly added to, for example, the E2 interface or O1 interface in the O-RAN specification. The E2 interface is defined in the O-RAN specification as the interface between the "Near-RT RIC" and the DU. The O1 interface is defined in the O-RAN specification as the interface between the "Non-RT RIC" and "Near-RT RIC" and the DU.

[0026] (Step S2) When the vDU20 to be measured receives an RTT measurement instruction between the DU and RU via the first interface, it obtains the addresses of all RU40 in the fronthaul network domain 30 from the fronthaul (FH) ARP (Address Resolution Protocol) table.

[0027] (Step S3) For each RU40 in the fronthaul network domain 30, the vDU20 to be measured performs RTT measurement using the address of the RU40 obtained in Step S2, via the O-RAN specification fronthaul Management Plane (M-Plane) interface (FH-MP).

[0028] (Step S4) The vDU20 to be measured obtains the RTT measurement response for each RU40 in the fronthaul network domain 30 via the O-RAN specification fronthaul management plane interface (FH-MP).

[0029] (Step S5) The vDU20 to be measured responds to the RIC10 via the first interface with the RTT between it and each RU40 obtained in step S4 by the RTT measurement response (RTT response). The acquisition unit 11 of the RIC10 obtains the RTT between the vDU20 to be measured and each RU40 based on the RTT response.

[0030] The RTT response in the first interface may be newly added to, for example, the A1 interface, E2 interface, or O1 interface in the O-RAN specification. The A1 interface is defined in the O-RAN specification as an interface between "Non-RT RIC" and "Near-RT RIC".

[0031] (Step S6) The determination unit 12 of RIC 10 determines a combination of RU and DU that satisfies the delay constraint between RU and DU in the fronthaul, based on the RTT between RU 40 and vDU 20. The control unit 13 of RIC 10 controls the communication connection between RU 40 and vDU 20 based on the result of the determination unit 12's determination of a combination of RU and DU that satisfies the FH delay constraint. For example, the control unit 13 performs scaling control such as scale-out or scale-in using vDU 20-1 and 20-2 provided in different buildings 200-1 and 200-2, respectively.

[0032] (Step S7) As a result of controlling the communication connection between RU40 and vDU20 in step S6, the control unit 13 of RIC10 notifies the vDU20 to be controlled of the communication connection setting information with the RU40, the communication partner (DU-RU connection config).

[0033] (Step S8) The controlled vDU20 notifies the RU40, the communication connection partner notified by RIC10, of the communication connection settings information with itself vDU20 (DU-RU connection config).

[0034] (Step S9) Communication is initiated using the combination of vDU20 and RU40 specified in the DU-RU connection config in Steps S7 and S8.

[0035] Furthermore, the acquisition unit 11 of RIC 10 may specify the combination of vDU 20 and RU 40 for which RTT measurement will be performed in the RTT measurement instruction between DU and RU via the first interface (step S1). In this case, the vDU 20 to be measured will perform RTT measurement on the RU 40 specified in the RTT measurement instruction between DU and RU via the first interface using the interface of the O-RAN specification front haul management plane.

[0036] Furthermore, the vDU20 to be measured may notify the RTT response (step S5) via the first interface of a combination of vDU20 and RU40 that satisfies the FH delay constraint. In this case, the acquisition unit 11 of RIC10 receives notification of a combination of vDU20 and RU40 that satisfies the FH delay constraint in the RTT response (step S5) via the first interface.

[0037] According to this embodiment, in an O-RAN specification wireless access network, when changing the communication connection between the RU and DU in the fronthaul, it is possible to determine whether or not the FH delay constraint is satisfied between the RU and DU. This makes it possible to appropriately change the communication connection between the RU and DU in the fronthaul.

[0038] Figure 3 shows an example of vDU scaling control in the fronthaul according to this embodiment. Figure 3(1) shows the case where a scale-out occurs from a configuration in which only the vDU 20-1 of station 200-1 is connected to one RU 40, to a configuration in which both the vDU 20-1 of station 200-1 and the vDU 20-2 of station 200-2 are connected. Figure 3(2) shows the case where a scale-in occurs from a configuration in which both the vDU 20-1 of station 200-1 and the vDU 20-2 of station 200-2 are connected to one RU 40, to a configuration in which only the vDU 20-1 of station 200-1 is connected.

[0039] Here, we consider a case where station building 200-1 and station building 200-2 are located in different places, and the communication delays between a single RU40, for example RU40-1, and vDU20-1 in station building 200-1 and vDU20-2 in station building 200-2 are different. In such a case, conventionally, RIC10 could not obtain the RTT between RU40-1 and vDU20-1 and between RU40-1 and vDU20-2, and therefore could not determine whether the combination of RU40-1 and vDU20-1 and the combination of RU40-1 and vDU20-2 satisfied the FH delay constraint. For this reason, when RIC10 scaled out, for example as shown in Figure 3(1), it sometimes scaled out without knowing whether the FH delay constraint was satisfied.

[0040] According to this embodiment, since the RIC 10 can obtain the RTT between the RU 40-1 and the vDU 20-1 and the RTT between the RU 40-1 and the vDU 20-2 through the first interface, it is possible to determine whether the combinations of the RU 40-1 and the vDU 20-1 and the RU 40-1 and the vDU 20-2 satisfy the FH delay constraint. Thereby, the RIC 10 can scale out on the condition that the FH delay constraint is satisfied, for example, when scaling out as shown in FIG. 3(1).

[0041] According to this embodiment, even when the RIC 10 controls the communication connection of a plurality of vDUs 20 existing in locations where the communication delay with one RU 40 is different, appropriate scaling control can be performed according to the number of accommodable RUs or the number of accommodable user terminals (User Equipment: UE) of each vDU 20, etc.

[0042] According to the above-described embodiment, an effect of appropriately changing the communication connection between the RU and the DU in the front hall can be obtained.

[0043] In addition, since, for example, an improvement in the overall service quality in a wireless communication system can be realized, it becomes possible to contribute to Goal 9 of the Sustainable Development Goals (SDGs) led by the United Nations, "Build resilient infrastructure, promote sustainable industrialization, and foster innovation".

[0044] As described above, the embodiments of the present invention have been described in detail with reference to the drawings. However, the specific configuration is not limited to this embodiment, and design changes and the like within the scope not departing from the gist of the present invention are also included.

[0045] For example, in the above-described embodiment, it is applied to a wireless access network conforming to the O-RAN specification, but it may be applied to a wireless access network other than the O-RAN specification.

[0046] Further, a computer program for realizing the functions of each of the above-described apparatuses may be recorded on a computer-readable recording medium, and the program recorded on this recording medium may be read into a computer system and executed. Here, the "computer system" may include hardware such as an OS and peripheral devices. Further, the "computer-readable recording medium" refers to a writable non-volatile memory such as a flexible disk, a magneto-optical disk, a ROM, a flash memory, a portable medium such as a DVD (Digital Versatile Disc), and a storage device such as a hard disk built into a computer system.

[0047] Furthermore, the "computer-readable recording medium" includes a volatile memory (for example, DRAM (Dynamic Random Access Memory)) inside a computer system that becomes a server or a client when a program is transmitted via a network such as the Internet or a communication line such as a telephone line, which holds the program for a certain period of time. Also, the above program may be transmitted from a computer system storing the program in a storage device or the like to another computer system via a transmission medium or by a transmission wave in the transmission medium. Here, the "transmission medium" for transmitting the program refers to a medium having a function of transmitting information, such as a network (communication network) such as the Internet or a communication line (communication line) such as a telephone line. Also, the above program may be for realizing a part of the above-described functions. Further, it may be a so-called difference file (difference program) that can realize the above-described functions in combination with a program already recorded in a computer system.

[0048] According to the present invention, the communication connection between the RU and the DU in the front hole can be appropriately changed.

[0049] 1... Radio access network, 10... RIC (communication control device), 11... Acquisition unit, 12... Determination unit, 13... Control unit, 20... vDU, 30... Front hole network domain, 40... RU, 200... Station building

Claims

1. A wireless communication system in which a communication control device that controls the communication connection between a Radio Unit (RU) and a Distributed Unit (DU) in an O-RAN specification wireless access network is equipped with an interface for acquiring the round-trip time between the DU and the RU being measured.

2. The wireless communication system according to claim 1, wherein the interface includes a round-trip time measurement instruction from the communication control device to the DU to be measured, and a round-trip time response from the DU to be measured to the communication control device.

3. The wireless communication system according to claim 2, wherein the interface includes notification from the DU under measurement to the communication control device of a combination of RU and DU that satisfies delay constraints between the RU and DU in the fronthaul.

4. The wireless communication system according to any one of claims 1 to 3, wherein the RU and the DU can communicate with each other via the same fronthaul network domain.

5. The wireless communication system according to claim 2, wherein the interface includes obtaining the round trip time via an A1 interface between a "Non-RT RIC" and a "Near-RT RIC".

6. The wireless communication system according to claim 2, wherein the interface includes obtaining the round trip time via an E2 interface between the DU and the "Near-RT RIC".

7. The wireless communication system according to claim 2, wherein the interface includes obtaining the round trip time via an O1 interface between the DU and the "Non-RT RIC".

8. A communication control method performed by a wireless communication system, wherein, in an O-RAN specification wireless access network, a communication control device that controls the communication connection between a Radio Unit (RU) and a Distributed Unit (DU) via a predetermined interface acquires the round-trip time between the DU and the RU to be measured.

9. A computer program that causes a computer to perform the step of obtaining the round-trip time between a DU and a RU, which are to be measured, by a communication control device that controls the communication connection between a RU (Radio Unit) and a DU (Distributed Unit) via a predetermined interface in an O-RAN specification wireless access network.

Images