Base station control device, base station control method, and base station control program

Abstract

This base station control device comprises an acquisition unit, a determination unit, a first estimation unit, a second estimation unit, and an instruction unit. The acquisition unit acquires movement information of a user terminal and a reference signal intermittently received from the user terminal. The determination unit determines, on the basis of the movement speed of the user terminal estimated from the movement information, whether to perform reference signal estimation for a period in which no reference signal is received from the user terminal through a first procedure using AI or through a second procedure not using AI. When the determination unit determines to perform the reference signal estimation through the first procedure, the first estimation unit estimates the reference signal through the first procedure. When the determination unit determines to perform the reference signal estimation through the second procedure, the second estimation unit estimates the reference signal through the second procedure. The instruction unit instructs a base station to perform, by using the reference signal estimated by the first estimation unit or the second estimation unit, channel estimation for the period in which no reference signal is received from the user terminal.

Description

Base Station Control Device, Base Station Control Method, and Base Station Control Program

[0001] The present invention relates to a base station control device, a base station control method, and a base station control program.

[0002] In Patent Document 1 below, a channel estimation method using an AI (Artificial Intelligence) model is disclosed.

[0003] Japanese Patent Translation of PCT International Publication No. 2008 - 507216

[0004] The base station control device disclosed in the present application includes an acquisition unit, a determination unit, a first estimation unit, a second estimation unit, and an instruction unit. The acquisition unit acquires movement information for determining the movement speed of a user terminal from a base station and reference signals intermittently received from the user terminal. The determination unit determines whether to perform the estimation of the reference signal during a period when the reference signal is not received from the user terminal based on the movement speed of the user terminal estimated from the movement information by using a first method using AI or a second method not using AI. The first estimation unit estimates the reference signal during a period when the reference signal is not received from the user terminal by the first method when it is determined by the determination unit that the estimation of the reference signal during the period when the reference signal is not received from the user terminal is to be performed by the first method. The second estimation unit estimates the reference signal during a period when the reference signal is not received from the user terminal by the second method when it is determined by the determination unit that the estimation of the reference signal during the period when the reference signal is not received from the user terminal is to be performed by the second method. The instruction unit instructs the base station to perform channel estimation during a period when the reference signal is not received from the user terminal using the reference signals estimated by the first estimation unit and the second estimation unit. The first estimation unit and the second estimation unit operate exclusively.

[0005] FIG. 1 is a diagram showing an example of a wireless communication system. FIG. 2 is a diagram showing an example of the structure of a frame in TDD. FIG. 3 is a diagram for explaining an example of the situation of a user terminal. FIG. 4 is a diagram showing an example of the relationship between the movement speed of a user terminal and the SRS estimation method. FIG. 5 is a flowchart showing an example of the SRS estimation method. FIG. 6 is a hardware configuration diagram showing an example of the functional configuration of a computer that realizes the base station control device.

[0006] The following describes in detail, with reference to the drawings, embodiments of the base station control device, base station control method, and base station control program disclosed in this application. However, the disclosed technology is not limited by the following embodiments.

[0007] [Wireless Communication System 1] Figure 1 shows an example of wireless communication system 1. Wireless communication system 1 includes a base station 10 and a base station control device 20.

[0008] The base station 10 is, for example, a gNB and has a CU (Central Unit) 11, a DU (Distributed Unit) 12, a plurality of RUs (Radio Units) 13, an output unit 110, and an input unit 120. Although the base station 10 illustrated in Figure 1 has one CU 11 and one DU 12, the base station 10 may have a plurality of CUs 11 and a plurality of DUs 12.

[0009] CU11 is located between the core network CN and DU12 and performs processing for the RRC (Radio Resource Control) layer and the PDCP (Packet Data Convergence Protocol) layer.

[0010] DU12 is located between CU11 and RU13 and performs processing for the RLC (Radio Link Control) layer, MAC (Medium Access Control) layer, and the higher physical layer. In the processing of the higher physical layer, a reference signal (hereinafter referred to as SRS (Sounding Reference Signal)) is extracted from the signals transmitted from the user terminal 30, and a channel estimation is performed between the user terminal 30 and DU12 using the extracted SRS.

[0011] The output unit 110 acquires information regarding the handover of RU 13 from CU 11 and outputs the acquired information to the base station control device 20. In this embodiment, the information regarding the handover is, for example, an RRC Reconfiguration message and an RRC Reconfiguration Complete message. The RRC Reconfiguration message includes the ID of the base station 10 from which the handover originated and the ID of the base station 10 to which the handover destination occurred. The output unit 110 also outputs the SRS extracted by DU 12 to the base station control device 20.

[0012] The input unit 120 inputs the SRS estimated by the base station control device 20 to the DU 12. During the period when the SRS is received from the user terminal 30, the DU 12 performs channel estimation using the SRS extracted from the signal transmitted from the user terminal 30, and during the period when the SRS is not received from the user terminal 30, it performs channel estimation using the SRS input from the input unit 120.

[0013] RU13 is connected to DU12 and performs processing of the lower physical layer and radio wave transmission and reception. A cell 14 is formed by radio waves transmitted from RU13, and user terminals 30 within the cell 14 perform wireless communication with the base station 10.

[0014] The base station control device 20 includes an acquisition unit 21, a storage unit 22, a determination unit 23, a first estimation unit 24, a second estimation unit 25, and an instruction unit 26. The base station control device 20 may be implemented as part of a function such as an SMO (Service Management and Orchestration) or a RIC (RAN Intelligent Controller).

[0015] The acquisition unit 21 acquires the SRS transmitted from the base station 10 for each user terminal 30 and stores the acquired SRS in the storage unit 22. The acquisition unit 21 also acquires handover information transmitted from the base station 10 for each user terminal 30 and outputs the acquired handover information to the determination unit 23.

[0016] The determination unit 23 determines, for each user terminal 30, whether the movement speed of the user terminal 30 is less than a predetermined first speed, based on the handover information output from the acquisition unit 21. The first speed is, for example, 20 km / h. If the determination unit 23 determines that the movement speed of the user terminal 30 is less than the first speed, the determination unit 23 stops the operation of the first estimation unit 24 and starts the second estimation unit 25. The handover information of the user terminal 30 is an example of movement information used to determine the movement speed of the user terminal 30.

[0017] Furthermore, the determination unit 23 determines, for each user terminal 30, whether the movement speed of the user terminal 30 is equal to or greater than a predetermined second speed, based on the handover information output from the acquisition unit 21. The second speed is, for example, 40 km / h. If the determination unit 23 determines that the movement speed of the user terminal 30 is equal to or greater than the second speed, the determination unit 23 stops the operation of the second estimation unit 25 and starts the first estimation unit 24. In this embodiment, the first estimation unit 24 and the second estimation unit 25 operate exclusively.

[0018] In this embodiment, the determination unit 23 estimates the movement speed of the user terminal 30 based on the handover information output from the acquisition unit 21. The determination unit 23 estimates the movement speed of the user terminal 30 based, for example, on the number of handovers per unit time. Specifically, for example, if the number of handovers performed per minute is three or more, the determination unit 23 determines that the movement speed of the user terminal 30 is equal to or greater than the second speed. Also, if the number of handovers performed per minute is one or less, the determination unit 23 determines that the movement speed of the user terminal 30 is less than the first speed.

[0019] The determination unit 23 determines, for example, that a handover of the corresponding user terminal 30 has been performed when a set of an RRC Reconfiguration message and a corresponding RRC Reconfiguration Complete message is output from the acquisition unit 21.

[0020] The first estimation unit 24 estimates the SRS for each user terminal 30 during periods when no SRS is received from the user terminal 30, using a first method employing AI. The first estimation unit 24, for example, refers to the storage unit 22 and uses the SRS received from the user terminal 30 up to that point to estimate the SRS for periods when no SRS is received from the user terminal 30 using a convolutional neural network (CNN). The first estimation unit 24 then outputs the estimated SRS to the instruction unit 26.

[0021] The second estimation unit 25 estimates the SRS for each user terminal 30 during periods when no SRS is received from the user terminal 30, using a second method that does not employ AI. The second estimation unit 25, for example, refers to the storage unit 22 and estimates the SRS received from the user terminal 30 immediately prior to the period when no SRS is received from the user terminal 30 as the SRS for those periods. The second estimation unit 25 then outputs the estimated SRS to the instruction unit 26. Note that the second method may be any other method that estimates the SRS without employing AI, such as averaging multiple SRSs received from the user terminal 30 immediately prior to the period, or linearly interpolating multiple SRSs received from the user terminal 30 immediately prior to the period.

[0022] The instruction unit 26 outputs the SRS estimated by the first estimation unit 24 and the second estimation unit 25 to the base station 10, instructing the base station 10 to perform channel estimation for periods when no SRS is received from the user terminal 30 using the estimated SRS. The SRS output from the instruction unit 26 is input to the DU 12 via the input unit 120, and the DU 12 uses the input SRS to perform channel estimation for periods when no SRS is received from the user terminal 30.

[0023] Here, the SRS transmitted from each user terminal 30 to the base station 10 is transmitted at the uplink transmission timing within a single frame 2, as shown in Figure 2, for example. Figure 2 is a diagram illustrating an example of the structure of frame 2 in TDD (Time Division Duplex). In the frame 2 illustrated in Figure 2, "D" indicates a subframe assigned to the downlink signal, "U" indicates a subframe assigned to the uplink signal, and "S" indicates a special subframe.

[0024] As the number of user terminals 30 belonging to base station 10 increases, it becomes impossible to accommodate SRS from all user terminals 30 within a single uplink subframe of frame 2. Therefore, focusing on a single user terminal 30, there may be periods when no SRS is included in the subframe, as shown in Figure 2, i.e., periods when no SRS is transmitted. This reduces the frequency of SRS transmission.

[0025] If the frequency of SRS transmissions from the user terminal 30 decreases, the accuracy of channel estimation using SRS for the user terminal 30 may decrease. When the accuracy of channel estimation decreases, the quality of communication between the user terminal 30 and the base station 10 deteriorates.

[0026] Therefore, it is conceivable to estimate the SRS during periods when it is not transmitted using AI. This can improve the accuracy of channel estimation between the user terminal 30 and the base station 10, and thereby improve the quality of communication between the user terminal 30 and the base station 10.

[0027] Here, for example, as shown in Figure 3, when the user terminal 30 is moving at a high speed, such as when moving together with the mobile body 3, the channel fluctuations are large, so it is preferable to estimate the SRS during periods when SRS is not transmitted using AI. However, estimating SRS using AI consumes a lot of computing resources. As a result, the load on the base station 10 increases.

[0028] On the other hand, as shown in Figure 3, for example, when the user terminal 30 is carried by a pedestrian, the movement speed of the user terminal 30 is slow, resulting in small channel fluctuations. Therefore, even if channel estimation is performed using the SRS received during the period in which SRS is transmitted, the quality of communication between the user terminal 30 and the base station 10 does not deteriorate significantly.

[0029] Therefore, in this embodiment, when the user terminal 30 is moving at a high speed, the first estimation unit 24 uses a first method using AI to estimate the SRS for the period during which no SRS is received from the user terminal 30. On the other hand, when the user terminal 30 is moving at a low speed, the second estimation unit 25 uses a second method that does not use AI to estimate the SRS for the period during which no SRS is received from the user terminal 30. This reduces the computing resources required to estimate the SRS for the period during which no SRS is received from the user terminal 30.

[0030] Furthermore, in this embodiment, as shown in Figure 4, for example, if the determination unit 23 determines that the movement speed of each user terminal 30 is less than the first speed, it stops the operation of the first estimation unit 24, which estimates the SRS using the first method, and activates the second estimation unit 25, which estimates the SRS using the second method.

[0031] Furthermore, in this embodiment, as shown in Figure 4, for example, if the determination unit 23 determines that the movement speed of each user terminal 30 is equal to or greater than the second speed, it stops the operation of the second estimation unit 25, which estimates the SRS using the second method, and starts the first estimation unit 24, which estimates the SRS using the first method.

[0032] Furthermore, in the range where the user terminal 30's movement speed is greater than or equal to the first speed and less than the second speed, the SRS using the current method is maintained, as shown in Figure 4, for example. This suppresses frequent starting and stopping of the first estimation unit 24 and the second estimation unit 25, and reduces the processing load associated with starting and stopping.

[0033] [Method for Estimating SRS] Figure 5 is a flowchart showing an example of a method for estimating SRS. The process illustrated in Figure 5 is performed for each user terminal 30. Note that the process illustrated in the flowchart of Figure 5 is an example of a base station control method.

[0034] First, the acquisition unit 21 determines whether or not it has acquired the SRS from the base station 10 (step S10). If the SRS has been acquired (step S10: Yes), the acquisition unit 21 stores the acquired SRS in the storage unit 22 (step S11). Then, the process shown in step S10 is executed again.

[0035] If SRS information has not been obtained (Step S10: No), the acquisition unit 21 determines whether or not information regarding handover has been obtained from the base station 10 (Step S12). If information regarding handover has not been obtained (Step S12: No), the process shown in Step S10 is executed again.

[0036] If information regarding a handover is obtained (step S12: Yes), the acquisition unit 21 sends the information regarding the handover to the determination unit 23. Based on the information regarding the handover, the determination unit 23 determines whether the movement speed of the user terminal 30 is less than the first speed (step S13).

[0037] If the user terminal 30's movement speed is less than the first speed (step S13: Yes), the determination unit 23 stops the operation of the first estimation unit 24 and starts the second estimation unit 25. As a result, the SRS for the period during which no SRS is received from the user terminal 30 is estimated by the second method until step S16, which will be described later, is executed (step S14). Then, the process shown in step S10 is executed again.

[0038] If the user terminal 30 is moving at a speed equal to or greater than the first speed (step S13: No), the determination unit 23 determines, based on the handover information, whether the user terminal 30 is moving at a speed equal to or greater than the second speed (step S15). If the user terminal 30 is moving at a speed less than the second speed (step S15: No), the process shown in step S10 is executed again.

[0039] If the user terminal 30's movement speed is greater than or equal to the second speed (step S15: Yes), the determination unit 23 stops the operation of the second estimation unit 25 and starts the first estimation unit 24. As a result, until step S14 is executed again, the SRS for the period during which no SRS is received from the user terminal 30 is estimated by the first method (step S16). Then, the process shown in step S10 is executed again.

[0040] [Hardware] The base station control device 20 is implemented by a computer 100 having a configuration such as that shown in Figure 6. Figure 6 is a hardware configuration diagram showing an example of the functional configuration of the computer 100 that implements the base station control device 20. The computer 100 includes a CPU 101, RAM (Random Access Memory) 102, ROM (Read Only Memory) 103, and auxiliary storage device 104. The computer 100 also includes a communication interface (I / F) 105, an input / output interface (I / F) 106, and a media interface (I / F) 107.

[0041] The CPU 101 operates based on programs stored in the ROM 103 or auxiliary storage device 104, and controls each part. The ROM 103 stores boot programs executed by the CPU 101 when the computer 100 starts up, as well as programs that depend on the computer 100's hardware.

[0042] The auxiliary storage device 104 is, for example, an HDD (Hard Disk Drive) or an SSD (Solid State Drive), and stores the program executed by the CPU 101 and the data used by that program. The CPU 101 reads the program from the auxiliary storage device 104, loads it onto the RAM 102, and executes the loaded program.

[0043] The communication I / F 105 receives signals and data from the base station 10 via a communication line such as a LAN (Local Area Network), and sends the received signals, data, etc. to the CPU 101. Also, the communication I / F 105 transmits the signals and data generated by the CPU 101 to the base station 10 via the communication line.

[0044] The CPU 101 controls the input device and the output device via the input / output I / F 106. The CPU 101 acquires the signals input from the input device via the input / output I / F 106 and sends them to the CPU 101. Also, the CPU 101 outputs the generated data to the output device via the input / output I / F 106.

[0045] The media I / F 107 reads the programs or data stored in the storage medium 108 and stores them in the auxiliary storage device 104. The storage medium 108 is, for example, an optical recording medium such as a DVD (Digital Versatile Disc), PD (Phase change rewritable Disk), a magneto-optical recording medium such as a MO (Magneto-Optical disk), a tape medium, a magnetic recording medium, or a semiconductor memory, etc.

[0046] The CPU 101 of the computer 100 realizes each process illustrated in the flowchart of FIG. 5 by executing the program loaded on the RAM 102. The base station control program for realizing each process illustrated in the flowchart of FIG. 5 is stored in the storage medium 108. The CPU 101 of the computer 100 reads the base station control program loaded on the RAM 102 from the storage medium 108 and stores it in the auxiliary storage device 104. As another example, the CPU 101 of the computer 100 may acquire the base station control program from another device via the communication line and store it in the auxiliary storage device 104.

[0047] As described above, the embodiments of the present disclosure have been explained. According to the base station control device 20 of this embodiment, it is possible to reduce the computer resources required for estimating the SRS during the period when the SRS is not received from the user terminal 30. Thereby, it is possible to contribute to the achievement of Goal 9, "Build the infrastructure for industry and technological innovation," of the Sustainable Development Goals (SDGs).

[0048] [Other] The disclosed technology is not limited to the above-described embodiments, and various modifications are possible within the scope of the gist thereof.

[0049] For example, in the above-described embodiments, the moving speed of the user terminal 30 was estimated from the frequency of handover of the user terminal 30 between the RUs 13 managed by one DU 12, but the disclosed technology is not limited to this. As another example, the moving speed of the user terminal 30 may be estimated by further considering the frequency of handover between the RUs 13 managed by different DUs 12, the frequency of handover between the RUs 13 managed by the DUs 12 connected to different CUs 11, or the frequency of handover between the RUs 13 of different base stations 10.

[0050] Also, in the above-described embodiments, the moving speed of the user terminal 30 was estimated from the frequency of handover of the user terminal 30, but the disclosed technology is not limited to this, and the moving speed of the user terminal 30 may be estimated by other methods. For example, data measured by various sensors (position sensor, acceleration sensor, etc.) provided in the user terminal 30 may be acquired, and the moving speed of the user terminal 30 may be estimated based on the acquired data.

[0051] Also, in the above-described embodiments, the base station control device 20 is provided outside the base station 10, but the disclosed technology is not limited to this. As another example, the base station control device 20 may be provided inside the base station 10 or inside the DU 12 of the base station 10.

[0052] Also, in the above-described embodiments, based on the moving speed of the user terminal 30, it is determined whether to estimate the SRS during the period when the SRS is not received from the user terminal 30 by either the first method using AI or the second method not using AI, but the disclosed technology is not limited to this. As another example, based on the magnitude of the variation per unit time of the radio wave propagation environment between the base station 10 and the user terminal 30, it may be determined whether to estimate the SRS during the period when the SRS is not received from the user terminal 30 by either the first method or the second method.

[0053] For example, if the magnitude of the fluctuation per unit time of the radio wave propagation environment is less than a first threshold, the SRS for the period during which no SRS is received from the user terminal 30 may be estimated using the second method. If the magnitude of the fluctuation per unit time of the radio wave propagation environment is greater than or equal to a second threshold which is greater than the first threshold, the SRS for the period during which no SRS is received from the user terminal 30 may be estimated using the first method.

[0054] Furthermore, among the processes described in the above embodiments, all or part of the processes described as being performed automatically can be performed manually, or all or part of the processes described as being performed manually can be performed automatically by known methods. In addition, the processing procedures, specific names, and various data and parameters shown in the above documents and drawings can be changed at will unless otherwise specified. For example, the various information shown in each figure is not limited to the information shown.

[0055] Furthermore, the components of each illustrated device are functionally conceptual and do not necessarily need to be physically configured as shown. In other words, the specific forms of distribution and integration of each device are not limited to those shown, and all or part of them can be functionally or physically distributed and integrated in any unit according to various loads and usage conditions.

[0056] Furthermore, the base station control device 20 described above may be implemented using multiple server computers, and depending on the function, it may be implemented by calling external platforms via API (Application Programming Interface) or network computing, allowing for flexible configuration changes.

[0057] CN Core Network 1 Wireless Communication System 2 Frame 3 Mobile Unit 10 Base Station 11 CU 110 Output Unit 120 Input Unit 12 DU 13 RU 14 Cell 20 Base Station Control Device 21 Acquisition Unit 22 Storage Unit 23 Determination Unit 24 First Estimation Unit 25 Second Estimation Unit 26 Instruction Unit 30 User Terminal 100 Computer 101 CPU 102 RAM 103 ROM 104 Auxiliary Storage Device 105 Communication Interface 106 Input / Output Interface 107 Media Interface 108 Storage Medium

Claims

1. An acquisition unit that acquires movement information for determining the movement speed of a user terminal from a base station and a reference signal intermittently received from the user terminal; a determination unit that determines, based on the movement speed of the user terminal estimated from the movement information, whether to estimate the reference signal for periods when the reference signal is not received from the user terminal using a first method using AI (Artificial Intelligence) or a second method without AI; a first estimation unit that estimates the reference signal for periods when the reference signal is not received from the user terminal using the first method if the determination unit determines that the estimation of the reference signal for periods when the reference signal is not received from the user terminal is to be performed using the first method; a second estimation unit that estimates the reference signal for periods when the reference signal is not received from the user terminal using the second method if the determination unit determines that the estimation of the reference signal for periods when the reference signal is not received from the user terminal is to be performed using the second method; A base station control device comprising: a first estimation unit and a second estimation unit, and an instruction unit that instructs the base station to perform channel estimation for a period during which the reference signal is not received from the user terminal using the reference signal estimated by the first estimation unit and the second estimation unit, wherein the first estimation unit and the second estimation unit operate exclusively.

2. The base station control device according to claim 1, wherein the determination unit determines, when the movement speed of the user terminal falls below a first speed, that the estimation of the reference signal for the period during which the reference signal is not received from the user terminal will be performed using the second method.

3. The base station control device according to claim 2, wherein the determination unit determines, when the movement speed of the user terminal becomes faster than the first speed, to estimate the reference signal for the period during which the reference signal is not received from the user terminal using the first method.

4. The base station control device according to claim 3, wherein the determination unit maintains the previous determination result when the movement speed of the user terminal is greater than or equal to the first speed and less than the second speed.

5. The base station control device according to any one of claims 1 to 4, wherein the movement information includes information regarding handovers performed by the user terminal, and the determination unit estimates the movement speed of the user terminal based on the number of handovers performed per unit time.

6. An acquisition step of acquiring movement information for determining the movement speed of a user terminal from a base station and a reference signal intermittently received from the user terminal; a determination step of determining whether to estimate the reference signal for periods when the reference signal is not received from the user terminal using a first method using AI (Artificial Intelligence) or a second method without AI, based on the movement speed of the user terminal estimated from the movement information; a first estimation step of estimating the reference signal for periods when the reference signal is not received from the user terminal using the first method if the determination step determines that the estimation of the reference signal for periods when the reference signal is not received from the user terminal is to be performed using the first method; a second estimation step of estimating the reference signal for periods when the reference signal is not received from the user terminal using the second method if the determination step determines that the estimation of the reference signal for periods when the reference signal is not received from the user terminal is to be performed using the second method; A base station control method comprising: an instruction step of instructing the base station to perform channel estimation for a period during which the reference signal is not received from the user terminal using the reference signal estimated in the first estimation step and the second estimation step, wherein the first estimation step and the second estimation step are performed exclusively.

7. Acquisition procedure for acquiring movement information for determining the movement speed of a user terminal from a base station and a reference signal intermittently received from the user terminal; Determination procedure for determining whether to estimate the reference signal during periods when the reference signal is not received from the user terminal using a first method using AI (Artificial Intelligence) or a second method without AI, based on the movement speed of the user terminal estimated from the movement information; First estimation procedure for estimating the reference signal during periods when the reference signal is not received from the user terminal using the first method, if the determination procedure determines that the estimation of the reference signal during periods when the reference signal is not received from the user terminal should be done using the first method; Second estimation procedure for estimating the reference signal during periods when the reference signal is not received from the user terminal using the second method, if the determination procedure determines that the estimation of the reference signal during periods when the reference signal is not received from the user terminal should be done using the second method; A base station control program that causes a computer to execute an instruction procedure which instructs the base station to perform channel estimation for a period when the reference signal is not received from the user terminal using the reference signal estimated in the first estimation procedure and the second estimation procedure, wherein the first estimation procedure and the second estimation procedure are performed exclusively.

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