JP7611124B2 - COMMUNICATION CONTROL SYSTEM, COMMUNICATION CONTROL METHOD, AND COMPUTER PROGRAM - Google Patents

Description

The present invention relates to a communication control system, a communication control method, and a computer program.

In recent years, user-centric RAN (Radio Access Network) has been considered as a "Beyond 5G" technology for the fifth generation mobile communication system (5G) and beyond. In user-centric RAN, "Cell-free Massive MIMO (CF-mMIMO)" technology (see, for example, Non-Patent Document 1) is used to ensure appropriate communication quality for each user. In CF-mMIMO technology, wireless signals are transmitted and received between user terminals (User Equipment: UE) using multiple distributed access points (Access Points: APs), and a signal processing device (Central Processing Unit: CPU) responsible for the multiple access points performs centralized signal processing.

In addition, the O-RAN (Open Radio Access Network) Alliance is considering opening up and making intelligent next-generation radio access networks such as 5G (see, for example, Non-Patent Document 2). Of the O-RAN specifications formulated by the O-RAN Alliance, Non-Patent Document 2 specifies interfaces related to parameter information and the like used in "Massive MIMO" technology. Non-Patent Document 2 describes control methods and interfaces for instructing "Massive MIMO" parameter information to an O-RAN Distributed Unit (O-DU) using a "Non-RT RIC (Non-Real Time RAN Intelligent Controller)" or a "Near-RT RIC (Near-Real Time RAN Intelligent Controller)." A "Non-RT RIC" is a controller that performs control at a cycle of one second or more. A "Near-RT" "RIC" is a controller that performs control at intervals of about 10 milliseconds to 1 second.

“Scalable Cell-Free Massive MIMO Systems”, IEEE Transactions on Communications, Volume 68, Issue 7, July 2020 O-RAN WG1, “Use Cases Detailed Specification”, v06.00.02

In order to apply CF-m MIMO technology so as to achieve various KPIs (Key Performance Indicators) when realizing a user-centric RAN in an O-RAN-specification radio access network (O-RAN), it is necessary to appropriately configure multiple access points (access point groups) that transmit and receive wireless signals for each user terminal from among the multiple access points distributed in the O-RAN. However, the information required to configure such access point groups and the interfaces for transmitting that information are not specified in the O-RAN specifications, making it difficult to configure an appropriate access point group for each user terminal in the O-RAN.

The present invention was made in consideration of these circumstances, and its purpose is to configure an appropriate access point group for each user terminal in an O-RAN-specification wireless access network.

(1) One aspect of the present invention is a communication control system comprising a control unit and a signal processing unit in a radio access network conforming to O-RAN (Open Radio Access Network) specifications, wherein the control unit transmits access point group information indicating a configuration of an access point group that transmits and receives radio signals for each user terminal from among a plurality of access points distributed in the radio access network to the signal processing unit, the signal processing unit receives the access point group information transmitted from the control unit, and performs signal processing related to the access point group based on the received access point group information , and the access point group information includes a list of user terminals included in a group of user terminals that are spatially multiplexed .
(2) One aspect of the present invention is the communication control system according to (1) above, in which the control unit is realized using a “Near-Real Time RAN Intelligent Controller (Near-RT RIC)”, the signal processing unit is realized using an O-RAN Distributed Unit (O-DU), and access point group information and a message for transmitting the access point group information are included in an interface between the “Near-RT RIC” and the O-DU.
(3) One aspect of the present invention is the communication control system of either (1) or (2) above, wherein the access point group information includes a list of access points included in the access point group for each user terminal.

( 4 ) One aspect of the present invention is a communication control method including the steps of: in a radio access network conforming to O-RAN (Open Radio Access Network) specifications, a control unit transmitting access point group information indicating a configuration of an access point group that transmits and receives radio signals for each user terminal from among a plurality of access points distributed in the radio access network to a signal processing unit; and the signal processing unit receiving the access point group information transmitted from the control unit and performing signal processing related to the access point group based on the received access point group information, wherein the access point group information includes a list of user terminals included in a group of user terminals to be spatially multiplexed .

( 5 ) One aspect of the present invention is a computer program for causing a control computer in a radio access network conforming to O-RAN (Open Radio Access Network) specifications to execute a step of transmitting access point group information indicating a configuration of an access point group that transmits and receives radio signals for each user terminal from among a plurality of access points distributed in the radio access network to a signal processing computer, and causing the signal processing computer to execute a step of receiving the access point group information transmitted from the control computer and performing signal processing related to the access point group based on the received access point group information , wherein the access point group information includes a list of user terminals included in a group of user terminals to be spatially multiplexed .

The present invention has the advantage that it is possible to configure an appropriate access point group for each user terminal in an O-RAN-specification wireless access network.

FIG. 2 is a block diagram showing an example of the configuration of a radio access network according to an embodiment. 1 is a block diagram showing an example of the configuration of a communication control system according to an embodiment; 4 is a sequence diagram showing a procedure of a communication control method according to an embodiment; 13 is a diagram illustrating an example of a configuration of example 1 of AP cluster information according to an embodiment. 13 is a configuration example of example 2 of AP cluster information according to an embodiment. FIG. 11 is an explanatory diagram showing an application example according to an embodiment.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
Fig. 1 is a block diagram showing an example of the configuration of a radio access network according to an embodiment. The radio access network (RAN) 1 shown in Fig. 1 is based on the O-RAN specification. However, in this embodiment, an interface such as information for configuring an access point group and a message for transmitting the information, which is not defined in the O-RAN specification, is newly added to the RAN 1.

In RAN1, multiple access points (AP) 2 (AP#1, AP#2, ...) are distributed. From the multiple AP2 distributed in RAN1, an access point group that transmits and receives wireless signals for each user terminal (UE) is configured. In the example of FIG. 1, for example, for UE#1, an access point group is configured from two AP2 (AP#1, AP#2). For example, for UE#2, an access point group is configured from two AP2 (AP#2, AP#4). For example, for UE#3, an access point group is configured from three AP2 (AP#4, AP#5, AP#6). For example, for UE#4, an access point group is configured from three AP2 (AP#6, AP#7, AP#8).

Each AP2 in the access point group of a certain user terminal transmits and receives wireless signals to and from the user terminal using its own antenna 3. For example, two AP2s (AP#1, AP#2) in the access point group of UE#1 transmit and receive wireless signals to and from UE#1 using their respective antennas 3.

Each access point group is communicatively connected to the O-DU 6 that it is responsible for. The O-DU 6 performs signal processing for the access point group that it is responsible for. In the example of FIG. 1, for example, O-DU #1 performs signal processing for the access point group (AP #4, AP #5, AP #6) of UE #3. For example, O-DU #2 performs signal processing for the access point group (AP #1, AP #2) of UE #1 and the access point group (AP #2, AP #4) of UE #2. For example, O-DU #3 performs signal processing for the access point group (AP #6, AP #7, AP #8) of UE #4.

The signal processing related to the access point group performed by O-DU6 is, for example, signal processing such as SU-MIMO (Single User MIMO) and MU-MIMO (Multi-User MIMO).

O-DU#1 is provided in a central site 4 and is connected to a core network CNW. O-DU#2 is provided in an edge site #1_5 and is connected to the core network CNW. A MEC (Multi-access Edge Computing) server 7 is provided in the edge site #1_5. O-DU#3 is provided in an edge site #2_5. A MEC server 7 is provided in the edge site #2_5.

The communication control system 10 is connected to each site 4, 5 for communication. The communication control system 10 controls each O-DU 6. The communication control system 10 provides the O-DU 6 with information for configuring an access point group corresponding to the user terminal. The O-DU 6 configures an access point group corresponding to the user terminal it is responsible for based on the information provided by the communication control system 10.

Figure 2 is a block diagram showing an example of the configuration of a communication control system according to this embodiment. In Figure 2, the communication control system 10 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 is realized using the SMO (Service and Management Orchestration) framework.

The "Non-RT RIC" 11 and the "Near-RT RIC" 12 collect information such as KPIs (Key Performance Indicators) from the O-DU 6 via the O1 interface. The O1 interface is defined in the O-RAN specifications. Parameters that can be collected by the O1 interface correspond to parameters defined in "3GPP, TS 28.552". For example, these parameters include "DL PRB usage", "UL PRB usage", "Average DL UE throughput", "Average UL UE throughput", and "Number of PDU Sessions requested".

The "Non-RT RIC" 11 analyzes the information collected from the O-DU 6 and changes the settings of the "Near-RT RIC" 12 based on the analysis results. The "Non-RT RIC" 11 provides the setting change information to the "Near-RT RIC" 12 via the A1 interface. The A1 interface is defined in the O-RAN specifications.

The "Near-RT RIC" 12 analyzes the information collected from the O-DU 6 and changes the settings of the O-DU 6 based on the analysis results. The "Near-RT RIC" 12 provides the setting change information to the O-DU 6 via the E2 interface. The E2 interface is defined in the O-RAN specifications.

The functions of the communication control system 10 are realized by the communication control system 10 being equipped with computer hardware such as a CPU and memory, and the CPU executing a computer program stored in the memory. The communication control system 10 may be configured using a general-purpose computer device, or may be configured as a dedicated hardware device. For example, the communication control system 10 may be configured using a server computer connected to a communication network. The functions of the communication control system 10 may be realized by cloud computing. The communication control system 10 may be realized by a single computer, or may be realized by distributing the functions of the communication control system 10 across multiple computers.

Next, we will explain the communication control method according to this embodiment. The communication control method according to this embodiment is a method for configuring an appropriate access point group for each user terminal. In the following explanation, the access point group may be referred to as an AP cluster.

The communication control method according to this embodiment will be described with reference to FIG. 3. FIG. 3 is a sequence diagram showing the steps of the communication control method according to this embodiment.

In this communication control method, the "Near-RT RIC" 12 corresponds to the control unit, and the O-DU 6 corresponds to the signal processing unit.

(Step S11) The "Near-RT RIC" 12 executes data collection from each O-DU 6 via the O1 interface. The information collected from each O-DU 6 includes information on the quality of wireless communication between the AP 2 and the user terminal, information on the computer resources of each site 4, 5, information on the transmission path resources between each site 4, 5 and the AP 2, the spatial distribution of user terminals, and the service usage status of user terminals.

The information on wireless communication quality is, for example, SINR (Signal to Interference Noise power Ratio) and RSSI (Received Signal Strength Indicator). The information on computer resources is, for example, computer resource usage (e.g., CPU usage and memory usage). The information on transmission path resources is, for example, transmission path bandwidth usage.

By configuring an access point group for each user terminal, the quality of wireless communication between AP2 and the user terminal changes, the amount of computer resources consumed at each site 4, 5 changes, and the amount of transmission path resources consumed between each site 4, 5 and AP2 changes. For this reason, this information is collected from each O-DU 6.

(Step S12) The "Near-RT RIC" 12 generates AP cluster information (access point group information) for each user terminal based on the information collected from each O-DU 6. The AP cluster information is information that indicates the configuration of the AP cluster.

For example, the "Near-RT RIC" 12 collects KPI information from each O-DU6 via the O1 interface. Using the KPI information collected from each O-DU6, the "Near-RT RIC" 12 determines AP cluster information for each user terminal by mathematical programming or machine learning. KPIs include, for example, the total throughput of each user terminal, the throughput satisfaction of each user terminal, the wireless resource usage rate of each AP2, the computer resource usage rate of each site, and the transmission line bandwidth usage rate between each site and the AP2.

(Step S13) The "Near-RT RIC" 12 sends an "Updated Configuration" message including the AP cluster information generated in step S12 to each O-DU 6 via the E2 interface. Each O-DU 6 receives the "Updated Configuration" message including the AP cluster information sent from the "Near-RT RIC" 12 via the E2 interface.

The O-DU 6 executes signal processing for the new AP cluster that it is responsible for, based on the AP cluster information included in the "Updated Configuration" message received via the E2 interface. As a result, each user terminal starts wireless communication using the new AP cluster.
Which O-DU6 is responsible for (accommodates) which user terminal (AP cluster) is determined as follows.
Among the APs 2 that have received a reference signal transmitted from a certain user terminal (UE #1 as an example here), the AP 2 (maximum reception power AP) that has the highest reception power (reference signal reception power) of the reference signal is connected to the O-DU #2 provided in the site (edge site #1_5 as an example here) to which the UE #1 (AP cluster of UE #1) is accommodated. The process of determining the accommodation of this user terminal (AP cluster) is performed by the "Non-RT RIC" 11 based on the power information (reference signal reception power at each AP 2) collected from the O-DU 6. The result of the determination of the accommodation of the user terminal (AP cluster) is notified to the O-DU 6 and the "Near-RT RIC" 12.
Furthermore, the AP cluster of a certain user terminal (UE #1 as an example here) is composed only of AP2 (including the maximum received power AP) whose power difference between the reference signal received power of UE #1 and the maximum received power AP is less than a predetermined threshold (e.g., 20 dB or 30 dB, etc.).

In this communication control method, the "Near-RT RIC" 12 has an information collection function that collects information via the O1 interface, an AP cluster information generation function that generates AP cluster information, and an information transmission function that transmits AP cluster information via the E2 interface. In addition, the O-DU 6 has an information reception function that receives AP cluster information via the E2 interface, and a signal processing function that performs signal processing related to the AP cluster based on the AP cluster information.

In the above-mentioned example of the communication control method, AP cluster information and a message for transmitting the AP cluster information are added to the E2 interface between the "Near-RT RIC" 12 and the O-DU6. This allows the AP cluster information to be transmitted from the "Near-RT RIC" 12 to the O-DU6 via the E2 interface. Therefore, when the AP cluster information is changed by the "Near-RT RIC" 12, the changed AP cluster information can be transmitted from the "Near-RT RIC" 12 to the O-DU6 via the E2 interface, and the O-DU6 can execute signal processing for the new AP cluster that it is responsible for based on the changed AP cluster information. This provides the effect of being able to configure an appropriate AP cluster for each user terminal according to the situation of the RAN1.

For example, when the AP cluster information of each user terminal is changed by the "Near-RT RIC" 12 in response to a change in the situation of the RAN1 related to the user terminal, such as when the user terminal moves or the service usage status of the user terminal changes, the changed AP cluster information of each user terminal is transmitted from the "Near-RT RIC" 12 to the O-DU6 via the E2 interface. The O-DU6 then executes signal processing related to the new AP cluster that it is responsible for based on the changed AP cluster information of each user terminal. As a result, the parameters of the AP cluster, MIMO, etc. used in the calculation of signal processing related to the AP cluster of each user terminal are appropriately changed in response to the movement of the user terminal or the change in the service usage status of the user terminal, so that it is possible to provide wireless communication quality suitable for the wireless communication environment after the user terminal moves and the service being used by the user terminal. This contributes to continuously ensuring the communication quality desired by the user.

Next, we will explain an example of AP cluster information related to this embodiment.

(Example 1 of AP cluster information)
FIG. 4 is a configuration example of example 1 of AP cluster information according to this embodiment. Example 1 of AP cluster information is a list of AP2 included in the AP cluster for each user terminal. In the example of FIG. 4, the AP cluster information has a user terminal identifier (UE ID) and a list (AP list) of AP2 (AP2 identifier (AP ID) for each user terminal. In the example of FIG. 4, an AP list (AP ID = 1, 2) is set for UE # 1 (UE ID = 1), an AP list (AP ID = 2, 4) is set for UE # 2 (UE ID = 2), an AP list (AP ID = 4, 5, 6) is set for UE # 3 (UE ID = 3), and an AP list (AP ID = 6, 7, 8) is set for UE # 4 (UE ID = 4). Note that the AP list illustrated in FIG. 4 is a list for convenience of explanation.

According to AP cluster information example 1, by providing a list (AP list) of APs 2 included in the AP cluster of the user terminal for each user terminal, it is possible to appropriately change the AP cluster that transmits and receives wireless signals for each user terminal in response to, for example, the movement of the user terminal or changes in the service usage status of the user terminal. For example, when the wireless communication quality required for each user terminal changes due to the movement of the user terminal or changes in the service usage status of the user terminal, it is possible to provide the O-DU6 with an AP list indicating the changed AP cluster that provides the required wireless communication quality for each user terminal. As a result, the O-DU6 executes signal processing related to the changed AP cluster of each user terminal, and the wireless communication quality required for each user terminal is maintained. This contributes to continuously ensuring the communication quality desired by the user.

(Example 2 of AP Cluster Information)
FIG. 5 is a configuration example of an example 2 of AP cluster information according to this embodiment. The example 2 of AP cluster information is a list (UE list) of user terminals included in a group of spatially multiplexed user terminals. The UE list is a list of user terminals that are spatially multiplexed in the same PRB (Physical Resource Block) in MU-MIMO signal processing. In the example of FIG. 5, the AP cluster information has a spatial multiplexing identifier (spatial multiplexing ID) and a list (UE list) of user terminals (UE ID) for each spatial multiplexing. In the example of FIG. 5, a UE list (UE ID = 1, 2) is set for the first spatial multiplexing (spatial multiplexing ID = 1), and a UE list (UE ID = 3, 4) is set for the second spatial multiplexing (spatial multiplexing ID = 2). Note that the UE list illustrated in FIG. 5 is a list for convenience of explanation.

According to AP cluster information example 2, by providing a list of user terminals (UE list) for each spatial multiplexing, it is possible to appropriately change the combination of user terminals to be spatially multiplexed in MU-MIMO in response to changes in the radio interference situation between user terminals due to changes in the wireless communication environment, such as changes in the positional relationship between user terminals. This maintains the wireless communication quality required for each user terminal. This contributes to continuously ensuring the communication quality desired by users.

The above-mentioned AP cluster information examples 1 and 2 may be combined as appropriate.

Figure 6 is an explanatory diagram showing an application example according to this embodiment. In the application example of Figure 6, UE #1, which is performing wireless communication via an AP cluster (AP #1, AP #2), moves. As a result of this UE #1 moving, the AP cluster of UE #1 is changed to a new AP cluster (AP #3, AP #4). This change in the AP cluster of UE #1 is realized by providing an AP list indicating UE #1's new AP cluster (AP #3, AP #4) from "Near-RT RIC" 12 to O-DU 6 via the E2 interface. This makes it possible to configure an appropriate AP cluster for each user terminal in response to changes in the situation of RAN 1.

In addition, as a result of the movement of UE #1, a change is made to spatially multiplexing the three UEs UE #1, UE #2, and UE #3 onto the same PRB. This change in spatial multiplexing is realized by providing a UE list indicating the change in spatial multiplexing from the "Near-RT RIC" 12 to the O-DU 6 via the E2 interface. This makes it possible to configure an appropriate AP cluster for each user terminal in response to changes in the situation of RAN 1.

As described above, this embodiment has the advantage of being able to configure an appropriate AP cluster (group of access points) for each user terminal in an O-RAN-specification wireless access network (RAN1).

As a result, it will be possible to improve the overall service quality in user-centric RAN, for example, and contribute to Goal 9 of the United Nations-led Sustainable Development Goals (SDGs), which is to "build resilient infrastructure, promote sustainable industrialization and foster innovation."

The above describes an embodiment of the present invention in detail with reference to the drawings, but the specific configuration is not limited to this embodiment and includes design modifications and the like that do not deviate from the gist of the present invention.

In addition, a computer program for implementing the functions of each of the above-mentioned devices may be recorded on a computer-readable recording medium, and the program recorded on the recording medium may be read into a computer system and executed. Note that the term "computer system" may include hardware such as an OS and peripheral devices.
In addition, the term "computer-readable recording medium" refers to a storage device such as a flexible disk, a magneto-optical disk, a ROM, a writable non-volatile memory such as a flash memory, a portable medium such as a DVD (Digital Versatile Disc), or a hard disk built into a computer system.

Furthermore, the term "computer-readable recording medium" includes devices that retain a program for a certain period of time, such as volatile memory (e.g., DRAM (Dynamic Random Access Memory)) within a computer system that serves 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.
The program may be transmitted from a computer system in which the program is stored 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" that transmits the program refers to a medium that has 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.
The program may be a program for implementing some of the above-mentioned functions, or may be a so-called differential file (differential program) that can implement the above-mentioned functions in combination with a program already recorded in the computer system.

1...Radio Access Network (RAN), 2...Access Point (AP), 3...Antenna, 4...Central site, 5...Edge site, 6...O-DU (O-RAN Distributed Unit), 7...MEC (Multi-access Edge Computing) server, 10...Communication control system, 11...Non-RT RIC, 12...Near-RT RIC, CNW...Core network, UE...User terminal

Claims (5)

In a radio access network conforming to the O-RAN (Open Radio Access Network) specification,
A control unit and a signal processing unit are provided,
the control unit transmits, to the signal processing unit, access point group information indicating a configuration of an access point group that transmits and receives a wireless signal for each user terminal from among a plurality of access points distributed in the wireless access network;
The signal processing unit includes:
receiving the access point group information transmitted from the control unit;
Executing signal processing related to the access point group based on the received access point group information ;
The access point group information includes a list of user terminals included in a user terminal group to be spatially multiplexed.
Communications control system. The control unit is realized using a "Near-RT RIC (Near-Real Time RAN Intelligent Controller)",
The signal processing unit is realized using an O-RAN Distributed Unit (O-DU),
For the interface between the "Near-RT RIC" and the O-DU, access point group information and messages for conveying access point group information were included;
The communication control system according to claim 1 . The access point group information includes a list of access points included in an access point group for each user terminal.
The communication control system according to claim 1 or 2. In a radio access network conforming to the O-RAN (Open Radio Access Network) specification,
a control unit transmitting access point group information indicating a configuration of an access point group that transmits and receives a wireless signal for each user terminal from among a plurality of access points distributed in the wireless access network to a signal processing unit;
the signal processing unit receiving the access point group information transmitted from the control unit, and executing signal processing related to an access point group based on the received access point group information ;
The access point group information includes a list of user terminals included in a user terminal group to be spatially multiplexed.
Communications control method. In a radio access network conforming to the O-RAN (Open Radio Access Network) specification,
The control computer
executing a step of transmitting access point group information indicating a configuration of an access point group that transmits and receives a wireless signal for each user terminal from among a plurality of access points distributed in the wireless access network to a signal processing computer;
The signal processing computer includes:
receiving the access point group information transmitted from the control computer, and executing signal processing related to the access point group based on the received access point group information;
A computer program for
The access point group information includes a list of user terminals included in a user terminal group to be spatially multiplexed.
Computer program.

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