Base station apparatus, control method, and program

Abstract

To enable acquisition of reference signal received power (RSRP) for each UE without using a synchronization signal in a base station device using a plurality of radio APs.SOLUTION: A base station device 10 includes a communication unit for communicating with one or more UEs using a plurality of connected radio APs, and the communication unit communicates with the UE using a radio AP group (AP cluster) selected for the UE by a control device 20 (external node) within the plurality of radio APs, for each radio terminal. The base station device 10 acquires information regarding RSRP corresponding to each radio channel between the UE and the plurality of radio APs based on a received SRS signal transmitted from the UE and received by the plurality of radio APs, for each UE. The base station device 10 notifies the control device 20 (external node) of the information regarding the acquired RSRP for each UE.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a base station apparatus, a control method, and a program connected to a plurality of wireless access points.

Background Art

[0002] In the next-generation system (Beyond 5G) of the fifth-generation mobile communication system (5G), Cell-free massive MIMO (CF-mMIMO) is being studied as a communication method for reducing interference between cells and enabling uniformization of user throughput (for example, Non-Patent Document 1). In CF-mMIMO, wireless signals are transmitted and received between a plurality of wireless access points (APs) distributedly arranged and user terminals (UEs), and a Central processing unit (CPU) performs batch processing of signals transmitted and received by the plurality of wireless APs. Thereby, it becomes possible to optimize the wireless signals spatially multiplexed for each UE in cooperation between the wireless APs.

[0003] In Non-Patent Document 1, in CF-mMIMO, an AP clustering technique for selecting a group of wireless APs used for data transmission and reception for each UE has been proposed in order to reduce the signal processing amount in the CPU. In this AP clustering technique, for each UE, a combination of the minimum number of wireless APs required to maintain wireless communication quality is selected, and the selected group of wireless APs is defined as an AP cluster. By performing signal processing on the AP cluster for each UE, it becomes possible to reduce the signal processing amount in the CPU while maintaining the wireless communication quality for the UE.

Prior Art Documents

Non-Patent Documents

[0004]

Non-Patent Document 1

[0005] In the above technology, the control of the AP cluster for each UE can be executed based on the received power of the reference signal (Reference Signal Received Power (RSRP)) received by each UE from each of a plurality of wireless APs. For example, when a plurality of wireless APs transmit a synchronization signal (SS) as a reference signal, each wireless AP needs to transmit a different synchronization signal so that the UE can obtain the RSRP corresponding to each wireless AP. However, when a plurality of wireless APs are densely arranged, the interference between the synchronization signals increases, and the acquisition accuracy of the RSRP may decrease. Also, when orthogonal radio resources are allocated to the synchronization signals to avoid interference between the synchronization signals, it leads to consumption of a large amount of radio resources.

[0006] Therefore, an object of the present invention is to provide a technology that enables obtaining the reference signal received power (RSRP) for each UE without using a synchronization signal in a base station apparatus using a plurality of wireless APs. [Means for Solving the Problems]

[0007] A base station apparatus according to an aspect of the present invention is a base station apparatus connected to a plurality of radio access points (APs), and is a communication means for communicating with one or more radio terminals using the plurality of radio APs. For each radio terminal, the communication means communicates with the radio terminal using a group of radio APs selected for the radio terminal by an external node among the plurality of radio APs. For each radio terminal, acquisition means for acquiring information regarding the reference signal reception power (RSRP) corresponding to the radio channel between the radio terminal and each of the plurality of radio APs based on the sounding reference (SRS) signal transmitted from the radio terminal and received by the plurality of radio APs; and notification means for notifying the external node of the information regarding the reference signal reception power for each radio terminal acquired by the acquisition means.

Advantages of the Invention

[0008] According to the present invention, in a base station apparatus using a plurality of radio APs, it becomes possible to acquire the reference signal reception power (RSRP) for each UE without using a synchronization signal.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Embodiments for Carrying Out the Invention

[0010] Hereinafter, embodiments will be described in detail with reference to the accompanying drawings. Note that the following embodiments do not limit the invention according to the claims, and not all combinations of the features described in the embodiments are essential to the invention. Two or more of the plurality of features described in the embodiments may be arbitrarily combined. Also, the same or similar configurations are given the same reference numerals, and redundant descriptions are omitted.

[0011] <Configuration of Radio Access Network> FIG. 1 shows a configuration example of a radio access network (RAN) according to an embodiment of the present disclosure. The RAN shown in FIG. 1 includes a base station device 10 connected to a plurality of radio access points (APs) and a control device 20. The RAN of this embodiment is, as an example, a RAN to which the O-RAN (Open RAN) specification is applied, and a Near-Real Time RAN Intelligent Controller (Near-RT RIC) in O-RAN can be implemented in the control device 20. Also, an O-RAN Distributed Unit (O-DU) or an O-RAN Central Unit (O-CU) in O-RAN can be implemented in the base station device 10. The base station device 10 and the control device 20 can communicate via the E2 interface in O-RAN (Non-Patent Document 2). The base station device 10 is also connected to a core network (CN). Each radio AP is provided with one or more antennas.

[0012] The base station device 10 is connected to a plurality of wireless APs (in this example, six APs #1 to #6) that are dispersedly arranged, and can perform MIMO communication by Cell-free massive MIMO (CF-mMIMO) using the plurality of wireless APs. The base station device 10 communicates with user terminals (UEs) (in this example, UEs #1 and #2), which are wireless terminals, using the plurality of wireless APs. Specifically, the base station device 10 communicates with each UE using a group of wireless APs that form an AP cluster set for the UE. The base station device 10 collectively performs signal processing on the wireless signals transmitted and received by the group of wireless APs that form an AP cluster in communication with the UE. The base station device 10 can perform signal processing such as SU-MIMO (Single User MIMO) or MU-MIMO (Multi-User MIMO) as signal processing related to the AP cluster.

[0013] In this embodiment, the setting (selection) of the AP cluster for each UE is performed by the control device 20. As shown in FIG. 2, the base station device 10 collects (acquires) information regarding the RSRP (RSRP information) corresponding to a plurality of wireless APs for each UE, and notifies the collected RSRP information to the control device 20. The notification of the RSRP information is performed via the E2 interface.

[0014] Based on the notified RSRP information, the control device 20 selects a group of wireless APs from among the plurality of wireless APs (APs #1 to #6) for the UE corresponding to the RSRP information, and sets the selected group of wireless APs as the AP cluster for the UE. For example, the control device 20 may select, as an AP cluster, the wireless AP corresponding to the maximum RSRP and one or more wireless APs corresponding to RSRPs whose difference from the maximum RSRP is equal to or less than a predetermined threshold among the plurality of wireless APs (APs #1 to #6). The control device 20 notifies the base station device 10 of AP cluster information (AP group information) indicating the set AP cluster. The base station device 10 communicates with the UE corresponding to the AP cluster information using the group of wireless APs indicated by the AP cluster information notified from the control device 20.

[0015] In the example of FIG. 2, an AP cluster for UE#1 and an AP cluster for UE#2 are set by the control device 20. In this example, as the AP cluster for UE#1, an AP cluster composed of four wireless APs #1 to #4 is set. Also, as the AP cluster for UE#2, an AP cluster composed of three wireless APs #3 to #5 is set. In this case, the base station device 10 communicates with UE#1 using APs #1 to #4, and communicates with UE#2 using APs #3 to #5.

[0016] The notification of RSRP information from the base station device 10 to the control device 20 (Near-RT RIC) is performed via the E2 interface. The E2 interface of O-RAN is used for the notification of Performance Measurements information defined in 3GPP TS28.552 (Non-Patent Document 3). In 3GPP TS28.552, as RSRP information, a measured value SS-RSRP of the reception strength (RSRP) of the synchronization signal (SS) is defined. Therefore, it can be assumed that RSRP information regarding SS-RSRP is notified from the base station device 10 to the control device 20 via the E2 interface (as in the comparative example shown in FIG. 5 described later). In this case, a plurality of wireless APs transmit a synchronization signal (SS) as a reference signal, and each UE acquires the RSRP (SS-RSRP) corresponding to each wireless AP.

[0017] As described above, in order for each UE to be able to acquire the RSRP corresponding to each wireless AP, each wireless AP needs to transmit a different synchronization signal. However, when a plurality of wireless APs are densely arranged, the interference between the synchronization signals increases, and the acquisition accuracy of the RSRP may decrease. Also, when orthogonal radio resources are allocated to the synchronization signals in order to avoid interference between the synchronization signals, it leads to the consumption of a large amount of radio resources.

[0018] Therefore, as described in detail below, in the base station apparatus 10 of the present embodiment, by acquiring the RSRP based on the sounding reference (SRS) signals transmitted from each UE, it is possible to acquire the RSRP for each UE without using the synchronization signal.

[0019] <Configuration of Base Station Apparatus> FIG. 3 shows a hardware configuration example of the base station apparatus 10 according to the present embodiment. The base station apparatus 10 includes one or more processors 11, a ROM 12, a RAM 13, a storage device (storage) 14 such as an HDD, and a communication device 15.

[0020] In the base station apparatus 10, for example, a program for realizing each function of the base station apparatus 10 described later, which is stored in any one of the ROM 12, the RAM 13, and the storage 14, is executed by the processor 11 such as a CPU. Note that the processor 11 may be replaced by one or more processors such as an ASIC (Application Specific Integrated Circuit), an FPGA (Field Programmable Gate Array), and a DSP (Digital Signal Processor). The communication device 15 is a communication interface for communicating with an external device (external nodes such as a wireless AP, the control device 20, and network nodes on the core network) under the control of the processor 11. The base station apparatus 10 may have a plurality of communication devices 15 with different connection destinations.

[0021] FIG. 4 shows a functional configuration (software configuration) example of the base station apparatus 10 according to the present embodiment. The base station apparatus 10 includes a first communication unit 401, a second communication unit 402, an SRS acquisition unit 403, a channel estimation unit 404, an RSRP calculation unit 405, and a weight generation unit 406. The SRS acquisition unit 403, the channel estimation unit 404, and the RSRP calculation unit 405 constitute an RSRP acquisition unit 410. These functional units of the base station apparatus 10 are realized in the base station apparatus 10 by the processor 11 executing a program stored in any one of the ROM 12, the RAM 13, and the storage 14.

[0022] The first communication unit 401 controls the communication device 15 to communicate with one or more UEs (wireless terminals) using a plurality of wireless APs (hereinafter referred to as N wireless APs #1 to #N) arranged in a distributed manner. In the present embodiment, the first communication unit 401 communicates with each UE using a wireless AP group (AP cluster) selected for the UE by the control device 20 (external node) among the wireless APs #1 to #N. The second communication unit 402 controls the communication device 15 to communicate with external nodes such as the control device 20 and network nodes on the core network.

[0023] The SRS acquisition unit 403 acquires SRS signals transmitted from each UE and received by the wireless APs #1 to #N. For example, the SRS acquisition unit 403 receives (acquires) an I signal indicating the in-phase component and a Q signal indicating the quadrature component of a signal obtained by converting the received SRS signal received by the wireless APs #1 to #N into a baseband signal from each wireless AP.

[0024] The channel estimation unit 404 performs channel estimation based on the received SRS signals acquired by the SRS acquisition unit 403. The channel estimation unit 404 generates an estimated channel matrix including estimated values of each wireless channel by estimating the wireless channels between the UE (target UE #k) that is the transmission source of the signal and each of the wireless APs #1 to #N based on the received SRS signal.

[0025] The RSRP calculation unit 405 acquires RSRP information based on the estimated channel matrix generated by the channel estimation unit 404. Specifically, the RSRP calculation unit 405 calculates the RSRP corresponding to each wireless channel based on the estimated values of the wireless channels between the target UE #k and each of the wireless APs #1 to #N (wireless AP #m) included in the estimated channel matrix, thereby acquiring information regarding the RSRP (RSRP information). When the estimated value (channel coefficient) of the wireless channel between UE #k and AP #m included in the estimated channel matrix is h k,m , the RSRP of the wireless AP #m for the UE #k is, for example, RSRP k,m [dB]=20log|h k,m| It is required. Further, as statistical information of RSRP, the following values may be used. - The average value of RSRP in the specified time window - The median value of RSRP in the specified time window - The distribution in the specified time window and division

[0026] In the above RSRP information acquisition process, the RSRP (that is, the uplink RSRP) in each of the wireless APs #1 to #N (wireless AP #m) is obtained. In this embodiment, it is assumed that time-division duplex (TDD) is applied. In this case, by utilizing the reciprocity between the uplink radio channel and the downlink radio channel, the channel estimation value in the uplink is used as the downlink channel estimation value, and the RSRP k,m (m = 1, 2,..., N) of each UE #k is obtained. Note that the RSRP calculation unit 405 may calculate the RSRP by calculating the received power based on the received SRS signals from the respective wireless APs #m acquired by the SRS acquisition unit 403. k,m may be calculated.

[0027] The weight generation unit 406 generates a precoding weight for MIMO transmission using the AP cluster for the target UE #k based on the estimated channel matrix generated by the channel estimation unit 404. The first communication unit 401 executes downlink data transmission (MIMO transmission) for the corresponding UE #k using the AP cluster by providing weight information indicating the precoding weight generated by the weight generation unit 406 to the wireless APs #1 to #N.

[0028] <Comparative Example> FIG. 5 is a sequence diagram showing an example of a process of acquiring RSRP information of each UE based on synchronization signals (SS) transmitted from N wireless APs #1 to #N connected to the base station apparatus 10, and shows a comparative example with respect to this embodiment.

[0029] In this comparative example, in communication with one or more UEs within the coverage areas of the N connected wireless APs #1 to #N, the base station apparatus 10 uses a wireless AP group (AP cluster) selected for each UE by the control apparatus 20 among the wireless APs #1 to #N. The control apparatus 20 selects a wireless AP group to be used for the UE based on the RSRP information for each UE provided from the base station apparatus 10, and transmits AP cluster information indicating the AP cluster composed of the wireless AP group to the base station apparatus 10. The base station apparatus 10 communicates with each UE using the AP cluster indicated by the AP cluster information received from the control apparatus 20.

[0030] For example, the base station apparatus 10 executes downlink communication with the UE as follows. First, in S501, the wireless APs #1 to #N receive the SRS signals transmitted from the UE, and in S502, transmit the received SRS signals to the base station apparatus 10.

[0031] When the base station apparatus 10 receives the received SRS signals from the wireless APs #1 to #N, in S503, it performs channel estimation based on the received SRS signals. Specifically, the base station apparatus 10 generates an estimated channel matrix including the estimated values of each wireless channel by performing estimation of the wireless channels between the corresponding UE and each of the wireless APs #1 to #N based on the received SRS signals. Further, in S504, the base station apparatus 10 generates a precoding weight for MIMO transmission using the AP cluster composed of the wireless AP group selected for the corresponding UE based on the estimated channel matrix. In S505, the base station apparatus 10 provides weight information indicating the generated precoding weight to the wireless APs #1 to #N, and thereby executes downlink data transmission (MIMO transmission) for the corresponding UE using the AP cluster (S506).

[0032] In this comparative example, the acquisition of RSRP information for each UE is performed based on synchronization signals (SS) transmitted from wireless APs #1 to #N. Specifically, in S511, wireless APs #1 to #N each transmit an SS. This SS is used not only for synchronization processing but also for RSRP acquisition in the UE. In order to enable the UE to acquire the RSRP between itself and each of wireless APs #1 to #N, the SSs transmitted from wireless APs #1 to #N need to be orthogonal to each other.

[0033] When the UE receives the SSs transmitted from each of wireless APs #1 to #N (S511), it acquires the RSRP from the received SSs. In this comparative example, the UE measures (calculates) the RSRP, which is the received power of the SSs from each of wireless APs #1 to #N, as channel estimation based on the SS. That is, the UE acquires the RSRP corresponding to the wireless channels between the UE and each of wireless APs #1 to #N.

[0034] In S512 and S513, the UE transmits a channel state information (CSI) report indicating the RSRP (SS-RSRP) acquired based on the SS to the base station apparatus 10 via, for example, wireless AP #1. When the base station apparatus 10 receives the CSI report (SS-RSRP) from the UE, in S514, it transmits the CSI report (SS-RSRP) to the control apparatus 20.

[0035] Based on the RSRP indicated by the CSI report received from the base station apparatus 10, in S515, the control apparatus 20 selects a wireless AP group for the corresponding UE, thereby setting an AP cluster composed of the wireless AP group. Then, in S516, the control apparatus 20 transmits AP cluster information indicating the set AP cluster to the base station apparatus 10.

[0036] When the base station apparatus 10 receives the AP cluster information from the control apparatus 20, in S517, it updates the AP cluster set for the corresponding UE. The base station apparatus 10 then performs communication (downlink data transmission and uplink data reception) with the corresponding UE using the updated AP cluster.

[0037] <Example of Processing Sequence> FIG. 6 is a sequence diagram showing an example of a process for acquiring RSRP information of each UE according to the present embodiment. The difference from the above-described comparative example (FIG. 5) is that the RSRP for each UE is acquired based on the SRS signals transmitted from each UE without using the synchronization signal (SS).

[0038] The wireless APs #1 to #N receive the SRS signals transmitted from the UE in S601, and transmit the received SRS signals to the base station apparatus 10 in S602. The wireless APs #1 to #N may, for example, convert the received SRS signals into baseband signals, and transmit the I signal indicating the in-phase component and the Q signal indicating the quadrature component of the baseband signals to the base station apparatus 10.

[0039] When the base station apparatus 10 receives the received SRS signals from the wireless APs #1 to #N, it performs channel estimation based on the received SRS signals in S603. Specifically, the base station apparatus 10 generates an estimated channel matrix including the estimated values of each wireless channel by performing estimation of the wireless channels between the UE (target UE) that is the transmission source of the SRS signal and each of the wireless APs #1 to #N based on the received SRS signals. Further, in S604, the base station apparatus 10 generates a precoding weight for MIMO transmission using an AP cluster composed of a group of wireless APs selected for the target UE based on the estimated channel matrix. The base station apparatus 10 executes downlink data transmission (MIMO transmission) to the target UE using the AP cluster by providing the weight information indicating the generated precoding weight to the wireless APs #1 to #N in S605 (S606).

[0040] Thereafter, in S607, the base station apparatus 10 acquires the RSRP information of the UE (target UE) that is the transmission source of the SRS signal based on the estimated channel matrix obtained by the channel estimation in S603 by the process described above with reference to FIG. 4. The base station apparatus 10 transmits the RSRP information (SRS-RSRP) acquired based on the SRS signals to the control apparatus 20 via the E2 interface in S608.

[0041] Based on the RSRP indicated by the RSRP information received from the base station device 10, at S609, the control device 20 selects a wireless AP group for the target UE, thereby setting an AP cluster composed of the wireless AP group. Then at S610, the control device 20 transmits AP cluster information indicating the set AP cluster to the base station device 10.

[0042] When the base station device 10 receives the AP cluster information from the control device 20, at S611, it updates the AP cluster set for the corresponding UE. The base station device 10 then performs communication (downlink data transmission and uplink data reception) with the corresponding UE using the updated AP cluster.

[0043] Note that the base station device 10 causes one of the wireless APs #1 to #N to transmit a synchronization signal (SS) at a predetermined time interval (S621). In this way, by causing one of the wireless APs #1 to #N to transmit the SS, the synchronization signal is shared among the wireless APs #1 to #N. In this embodiment, this SS is used for synchronization processing without being used for RSRP measurement in the UE.

[0044] According to this embodiment, the RSRP information (SRS-RSRP) can be notified from the base station device 10 to the control device 20 (Near-RT RIC) via the E2 interface. Regarding such notification of SRS-RSRP, as a notification based on 5G Performance Measurements information, for example, the following description (Section 5.1.22.4) can be added to Section 5.1.22 of 3GPP TS28.552. TIFF0007700085000001.tif66138

[0045] As described above, the base station apparatus 10 of the present embodiment includes a communication unit that communicates with one or more UEs using a plurality of connected wireless APs. For each wireless terminal, the communication unit communicates with the UE using a wireless AP group (AP cluster) selected for the UE by a control device 20 (external node) among the plurality of wireless APs. The base station apparatus 10 acquires information (RSRP information) regarding the RSRP corresponding to the radio channel between the UE and each of the plurality of wireless APs based on the SRS signals transmitted from the UE and received by the plurality of wireless APs for each UE. The base station apparatus 10 notifies the acquired RSRP information for each UE to the control device 20 (external node). As described above, according to the present embodiment, in the base station apparatus 10 using a plurality of wireless APs, it is possible to acquire the RSRP for each UE without using the synchronization signal (SS), and it is possible to notify the control device 20 (external node) of the RSRP information regarding the RSRP.

[0046] [Other Embodiments] The remote operation device according to the above-described embodiment can be realized by a computer program for causing a computer to function as the remote operation device. The computer program is stored in a computer-readable storage medium and can be distributed, or can be distributed via a network.

[0047] The disclosure of this specification includes the following base station apparatus, control method, and program. (Item 1) A base station apparatus connected to a plurality of wireless access points (APs), communication means for communicating with one or more wireless terminals using the plurality of wireless APs, wherein for each wireless terminal, the communication means communicates with the wireless terminal using a wireless AP group selected for the wireless terminal by an external node among the plurality of wireless APs, and the communication means; For each wireless terminal, acquisition means for acquiring information regarding the reference signal received power (RSRP) corresponding to the radio channel between the wireless terminal and each of the plurality of wireless APs based on the sounding reference (SRS) signals transmitted from the wireless terminal and received by the plurality of wireless APs; notification means for notifying the external node of the information regarding the reference signal received power for each wireless terminal acquired by the acquisition means; A base station apparatus characterized by comprising the above. (Item 2) The acquisition means estimates, for each wireless terminal, a channel matrix between the wireless terminal and the plurality of wireless APs based on the SRS signal, and acquires information regarding the reference signal received power based on the obtained estimated channel matrix. The base station apparatus according to Item 1, characterized by the above. (Item 3) The acquisition means calculates the reference signal received power corresponding to each radio channel based on the estimated values of the radio channels between the corresponding wireless terminal and each of the plurality of wireless APs included in the estimated channel matrix. The base station apparatus according to Item 2, characterized by the above. (Item 4) The estimated channel matrix is used for acquiring information regarding the reference signal received power and for generating a precoding weight for MIMO transmission using the wireless AP group. The base station apparatus according to Item 2 or 3, characterized by the above. (Item 5) The communication means causes one of the plurality of wireless APs to transmit a synchronization signal so that the synchronization signal is shared among the plurality of wireless APs, and the synchronization signal is not used for RSRP measurement at the wireless terminal. The base station apparatus according to any one of Items 1 to 4, characterized by the above. (Item 6) The information regarding the reference signal received power notified to the external node by the notification means is used for the selection of the wireless AP by the external node. The base station apparatus according to any one of Items 1 to 5, characterized in that... (Item 7) The communication means receives, from the external node, AP group information indicating a group of wireless APs selected based on information regarding the reference signal reception power, and communicates with a corresponding wireless terminal using the group of wireless APs indicated by the AP group information. The base station apparatus according to Item 6, characterized in that... (Item 8) A Near-Real Time RAN Intelligent Controller (Near-RT RIC) in Open RAN (O-RAN) is implemented in the external node, An O-RAN Distributed Unit (O-DU) or an O-RAN Central Unit (O-CU) in O-RAN is implemented in the base station apparatus, The notification means notifies the external node of information regarding the reference signal reception power via the E2 interface of O-RAN. The base station apparatus according to any one of Items 1 to 7, characterized in that... (Item 9) A control method for a base station apparatus connected to a plurality of wireless access points (APs), comprising: A communication step of communicating with one or more wireless terminals using the plurality of wireless APs, wherein, for each wireless terminal, communication is performed with the wireless terminal using a group of wireless APs selected for the wireless terminal by an external node from among the plurality of wireless APs; and An acquisition step of acquiring, for each wireless terminal, information regarding the reference signal reception power (RSRP) corresponding to a wireless channel between the wireless terminal and each of the plurality of wireless APs, based on sounding reference (SRS) signals transmitted from the wireless terminal and received by the plurality of wireless APs; and A notification step of notifying the external node of the information regarding the reference signal reception power for each wireless terminal acquired in the acquisition step. A control method characterized by including the above steps. (Item 10) A program for causing a computer included in a base station apparatus to execute each step of the control method described in item 9.

[0048] Note that according to the present invention, for example, since it becomes possible to notify RSRP information to an external node that controls CF-mMIMO communication in a base station apparatus using a plurality of wireless APs, it becomes possible to contribute to Goal 9, "Build the infrastructure for industry and innovation," of the Sustainable Development Goals (SDGs) led by the United Nations.

[0049] The invention is not limited to the above-described embodiments, and various modifications and changes are possible within the scope of the gist of the invention.

Explanation of Signs

[0050] 10: Base station apparatus (O-CU / DU), 20: Control apparatus (Near-RT RIC), 11: Processor, 401: First communication unit, 402: Second communication unit, 410: RSRP acquisition unit

Claims

1. A base station device connected to a plurality of wireless access points (APs), communication means for communicating with one or more wireless terminals using the plurality of wireless APs, wherein for each wireless terminal, communication with the wireless terminal is performed using a group of wireless APs selected for the wireless terminal by an external node among the plurality of wireless APs; the communication means; acquisition means for acquiring information regarding reference signal received power (RSRP) corresponding to a radio channel between the wireless terminal and each of the plurality of wireless APs based on a sounding reference (SRS) signal transmitted from the wireless terminal and received by the plurality of wireless APs, for each wireless terminal; notification means for notifying the external node of the information regarding the reference signal received power for each wireless terminal acquired by the acquisition means; A base station device comprising the above.

2. The acquisition means estimates, for each wireless terminal, a channel matrix between the wireless terminal and the plurality of wireless APs based on the SRS signal, and acquires information regarding the reference signal received power based on the obtained estimated channel matrix The base station device according to claim 1, characterized by the above.

3. The acquisition means calculates the reference signal received power corresponding to each radio channel based on the estimated values of the radio channels between the corresponding wireless terminal and each of the plurality of wireless APs included in the estimated channel matrix The base station device according to claim 2, characterized by the above.

4. The estimated channel matrix is used for acquiring information regarding the reference signal received power and for generating a precoding weight for MIMO transmission using the group of wireless APs The base station device according to claim 2, characterized by the above.

5. The communication means causes one of the plurality of wireless APs to transmit a synchronization signal so that the synchronization signal is shared among the plurality of wireless APs, and the synchronization signal is not used for measurement of RSRP at the wireless terminal The base station device according to any one of claims 1 to 4, characterized by the above.

6. The information regarding the reference signal received power notified to the external node by the notification means is used for selection of a wireless AP by the external node The base station device according to any one of claims 1 to 4, characterized by the above.

7. The communication means receives, from the external node, AP group information indicating a wireless AP group selected based on information regarding the received reference signal power, and communicates with a corresponding wireless terminal using the wireless AP group indicated by the AP group information. The base station device according to claim 6, characterized in that.

8. The external node is equipped with a Near-Real Time RAN Intelligent Controller (Near-Real Time RAN Intelligent Controller) in O-RAN (Open RAN). The base station device is equipped with an O-RAN Distributed Unit (O-RAN Distributed Unit) or an O-RAN Central Unit (O-RAN Central Unit) in O-RAN. The notification means notifies the external node of information regarding the received reference signal power via the E2 interface of O-RAN. The base station device according to any one of claims 1 to 4, characterized in that.

9. A control method for a base station device connected to a plurality of wireless access points (APs), comprising: A communication step of communicating with one or more wireless terminals using the plurality of wireless APs, wherein, for each wireless terminal, the wireless terminal is communicated with using a wireless AP group selected for the wireless terminal by an external node among the plurality of wireless APs; the communication step; An acquisition step of acquiring, for each wireless terminal, information regarding the received reference signal power (RSRP) corresponding to the wireless channel between the wireless terminal and each of the plurality of wireless APs based on the sounding reference (SRS) signal transmitted from the wireless terminal and received by the plurality of wireless APs; A notification step of notifying the external node of the information regarding the received reference signal power for each wireless terminal acquired in the acquisition step; A control method characterized by including.

10. A program for causing a computer included in a base station device to execute each step of the control method according to claim 9.

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