Base station, terminal device, and communication method

Abstract

This base station comprises: a scheduling adjustment unit that adjusts the schedule of a combination of antenna devices that perform transmission and reception at the same time among a plurality of antenna devices arranged dispersedly such that the combination suppresses interference which occurs between an uplink and a downlink and includes self-interference; and a control unit that controls the operation of each antenna device on the basis of the result of the adjustment by the scheduling adjustment unit.　

Description

Base station, terminal device, and communication method

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

[0002] The current 5th generation mobile communication system (5G) uses the Time Division Duplex (TDD) method, which often allocates a large amount of time resources to the downlink, making it difficult to handle large amounts of traffic on the uplink. Therefore, the Full Duplex (FD) method, which simultaneously transmits and receives data on the downlink and uplink at the same time, is attracting attention.

[0003] When an uplink signal (hereinafter referred to as "UL signal") and a downlink signal (hereinafter referred to as "DL signal") are transmitted and received at the same time and at the same frequency, ideally, twice the frequency utilization efficiency of conventional methods can be achieved. However, degradation of transmission quality due to cross link interference (CLI), which is interference between the uplink and downlink (inter-link interference), becomes a problem. Therefore, the subband non-overlapping full duplex (SBFD) method has been proposed. The SBFD method is an FD method in which the influence of CLI is relatively small and subbands do not overlap on the gNB side within the TDD band.

[0004] In a base station (gNB) using the FD method or the SBFD method, UL signals are received and DL signals are transmitted at the same time between multiple terminal devices that form links. Figure 15 is a diagram for explaining the conventional problem. As shown in the wireless communication system S shown in Figure 15, when a base station receives an UL signal transmitted from a terminal device #1 at the same time and transmits a DL signal to a terminal device #2, interference called self-interference (SI) occurs due to the DL signal transmitted by the base station itself.

[0005] Conventionally, in order to eliminate self-interference, functions to remove interference components using analog circuits or signal processing have been proposed (see, for example, Non-Patent Document 2). Furthermore, in the conventional technology currently being discussed in 3GPP (registered trademark) Release 19, interference is reduced by adopting SBFD, in which subbands do not overlap on the base station (gNB) side. Furthermore, base stations (gNBs) have the function of measuring CLI from other base stations (gNBs) using NZP-CSI-RS (Non-zero power Channel State Information Reference Signal) or NCD-SSB (Non-Cell Defining Synchronization Signal Block) (see, for example, Non-Patent Document 3). Based on the measurement results, the base station (gNB) can reduce CLI using antenna directivity and beamforming.

[0006] “New WID: Evolution of NR duplex operation: Sub-band full duplex (SBFD)”, CMCC (Moderator, RAN1 VC), 3GPP TSG RAN Meeting #102, RP-234035, Edinburgh, Scotland, December 11-15, 2023Ashutosh Sabharwal, Philip Schniter, Dongning Guo, Daniel W. Bliss, Sampath Rangarajan, and Risto Wichman, “In-Band Full-Duplex Wireless: Challenges and Opportunities”, IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 32, NO. 9, SEPTEMBER 2014, pp.1637-1652 “Discussion on CLI handling for sub-band full duplex (SBFD)”, NTT DOCOMO, INC, 3GPP TSG RAN WG1 #116 R1-2401118, Athens, Greece, February 26th - March 1st, 2024

[0007] However, self-interference is interference caused by the base station itself as an interference source. Self-interference can reach the base station as interference over a short propagation distance, so it is likely to be the most severe form of CLI. Therefore, CLI reduction techniques using analog circuits or CLI reduction techniques using antenna directivity or beamforming functions may not be sufficient to reduce the impact of self-interference. Furthermore, compared to SBFD, which is frequency-separated, the impact of CLI is more pronounced in FD, so further reduction techniques are required.

[0008] In view of the above circumstances, an object of the present invention is to provide a technique that can reduce the degradation of transmission quality due to CLI.

[0009] One aspect of the present invention is a base station comprising: a scheduling adjustment unit that adjusts the schedule of a combination of antenna devices that transmit and receive at the same time, among a plurality of antenna devices that are distributed and arranged so that the combination suppresses interference that occurs between the uplink and downlink, including self-interference; and a control unit that controls the operation of each antenna device based on the results adjusted by the scheduling adjustment unit.

[0010] One aspect of the present invention is a terminal device that includes a beam report adjustment unit that transmits a beam report containing information about beams transmitted by a connected antenna device and one or more other unconnected antenna devices among a plurality of antenna devices that are distributedly arranged, to a base station that accommodates the plurality of antenna devices via the connected antenna device.

[0011] One aspect of the present invention is a communication method performed by a base station that performs wireless communication with a terminal device via a plurality of antenna devices that are distributed in a dispersed manner, in which a schedule adjustment is performed for a combination of antenna devices that transmit and receive at the same time among the plurality of antenna devices that are distributed in a dispersed manner so that the combination suppresses interference that occurs between the uplink and the downlink, including self-interference, and the operation of each antenna device is controlled based on the adjusted results.

[0012] According to the present invention, it is possible to reduce the degradation of transmission quality due to CLI.

[0013] 1 is a diagram illustrating an example of the configuration of a wireless communication system in a first embodiment. FIG. 2 is a diagram illustrating an example of the configuration of a base station and an antenna device in the first embodiment. FIG. 3 is a diagram illustrating an example of the configuration of a terminal device in the first embodiment. FIG. 4 is a diagram for explaining an overview of a wireless communication system in the first embodiment. FIG. 5 is a diagram for explaining an overview of a wireless communication system in the first embodiment. FIG. 6 is a flowchart illustrating the flow of scheduling processing performed by a base station in the first embodiment. FIG. 7 is a diagram illustrating an example of scheduling adjustment due to a change in resource block allocation in the first embodiment. FIG. 8 is a diagram illustrating an example of scheduling adjustment due to a change in antenna device in the first embodiment. FIG. 9 is a diagram illustrating an example of the configuration of a base station and an antenna device in a second embodiment. FIG. 10 is a diagram illustrating an example of a CLI table in the second embodiment. FIG. 11 is a flowchart illustrating the flow of CLI table update processing performed by a base station in the second embodiment. FIG. 12 is a flowchart illustrating the flow of scheduling processing performed by a base station in the second embodiment. FIG. 13 is a diagram illustrating an example of the configuration of a base station and an antenna device in a third embodiment. FIG. 14 is a flowchart illustrating the flow of scheduling processing performed by a base station in the third embodiment. FIG. 15 is a diagram for explaining problems with the prior art.

[0014] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0015] (First embodiment) Fig. 1 is a diagram showing an example of the configuration of a wireless communication system 100 in the first embodiment. The wireless communication system 100 is, for example, a distributed antenna system. The wireless communication system 100 includes a base station 10 and an antenna device 20. Fig. 1 shows a configuration in which the wireless communication system 100 includes one base station 10 and three antenna devices 20-1 to 20-3, but the number of base stations 10 and antenna devices 20 included in the wireless communication system 100 is not particularly limited.

[0016] The base station 10 and each antenna device 20 are connected via wires (e.g., optical fiber). Three antenna devices 20-1 to 20-3 are accommodated in the same base station 10. The three antenna devices 20-1 to 20-3 are located in different spatial locations. Each antenna device 20 is equipped with multiple antenna elements. The multiple antenna elements form an antenna panel, and beams can be formed using the antenna panel. Note that each antenna device 20 may be equipped with multiple antenna panels. Furthermore, each antenna device 20 can transmit and receive using multiple beams (e.g., beam 1, beam 2, ...) by using the antenna panel. Note that the number of beams available to each antenna device 20 may be the same or different. In the following description, multiple antenna panels equipped in the same antenna device 20 are also referred to as antenna panels at the same site.

[0017] The wireless communication system 100 in this embodiment employs either the FD method, the SBFD method, or the Dynamic Time Division Duplex (TDD) method, which aggregates multiple base stations using a central station (CU). Dynamic TDD is a communication method that allows dynamic switching of uplink and downlink time slots in a TDD frame pattern for each cell or each base station. Therefore, in the wireless communication system 100, uplink and downlink communications are performed at the same time. Therefore, when a base station 10 performs uplink and downlink communications at the same time via an antenna panel at the same site, self-interference, a type of CLI, occurs. Furthermore, when a base station 10 performs uplink and downlink communications at the same time and at the same frequency via each antenna device 20, CLI occurs due to interference between the antenna devices 20. Therefore, the base station 10 in the present invention reduces the degradation of transmission quality due to the above-mentioned CLI. In the first embodiment, a configuration for reducing deterioration of transmission quality due to self-interference, which is considered to be a major contributor to deterioration of transmission quality among CLIs, will be described.

[0018] The base station 10 performs wireless communication with the terminal device 30 via the antenna device 20. The base station 10 transmits, for example, a signal to be transmitted (hereinafter referred to as a "transmission signal") to the terminal device 30 via the antenna device 20. The base station 10 receives, for example, a signal transmitted from the terminal device 30 via the antenna device 20. The base station 10 schedules the timing of signal transmission and reception, and performs wireless communication with the terminal device 30 via the antenna device 20 based on the scheduling result.

[0019] The antenna device 20 wirelessly transmits a transmission signal output from the base station 10 as a DL signal to the terminal device 30. The antenna device 20 receives a UL signal wirelessly transmitted from the terminal device 30. In the following description, the direction from the base station 10 to the terminal device 30 via the antenna device 20 is referred to as the downlink direction, and the direction from the terminal device 30 to the base station 10 via the antenna device 20 is referred to as the uplink direction.

[0020] The terminal device 30 is a user terminal (UE: User Equipment), such as a smartphone terminal or a tablet terminal. The terminal device 30 performs wireless communication with the base station 10 via the antenna device 20. The terminal device 30 transmits a beam report to the base station 10 via the antenna device 20, the beam report including information on beams transmitted by at least the connected antenna device 20. Note that the terminal device 30 transmits a beam report to the base station 10 via the connected antenna device 20, the beam report including information on beams transmitted by one or more other antenna devices 20 (unconnected antenna devices 20) in addition to the connected antenna device 20, in order to instruct the base station 10 to change the antenna device 20 and the beam.

[0021] (Device Configuration) Next, a description will be given of the specific configuration of the base station 10 and the antenna device 20. Fig. 2 is a diagram showing an example of the configuration of the base station 10 and the antenna device 20 in the first embodiment. The base station 10 includes a control unit 11, a DL processing unit 12, a UL processing unit 13, and a scheduling adjustment unit 14.

[0022] The control unit 11 controls the operation of the base station 10. The control unit 11 performs, for example, scheduling of UL reception or DL ​​transmission according to conventional technology. Here, the scheduling of UL reception or DL ​​transmission according to conventional technology is scheduling that does not take into account the influence of CLI. Therefore, depending on the scheduling, there is a possibility that self-interference or CLI may occur, as explained in FIG. 15 . UL reception means reception of a UL signal. DL transmission means transmission of a DL signal.

[0023] The control unit 11 performs transmission and reception processing based on the scheduling of UL reception or DL ​​transmission according to the conventional technology described above until the scheduling is adjusted by the scheduling adjustment unit 14. When the scheduling is adjusted by the scheduling adjustment unit 14, the control unit 11 causes the DL processing unit 12 and the UL processing unit 13 to perform transmission and reception processing based on the adjusted scheduling result.

[0024] Furthermore, the control unit 11 outputs the data signal transmitted from the core network to the DL processing unit 12. The control unit 11 transmits the data signal output from the UL processing unit 13 to the core network.

[0025] The DL processing unit 12 generates a transmission signal by performing predetermined signal processing on the data signal based on the scheduling result by the control unit 11. Specifically, when the transmission timing of the DL signal indicated by "DL" in the scheduling result by the control unit 11 arrives, the DL processing unit 12 generates a transmission signal by performing modulation processing (radio frequency processing) on ​​the data signal input from the control unit 11. The DL processing unit 12 transmits the generated transmission signal to the antenna device 20 to which the destination terminal device 30 is connected.

[0026] The UL processing unit 13 acquires the received signal (UL signal) received by the antenna device 20 based on the scheduling result by the control unit 11. Specifically, when the timing for receiving the UL signal indicated by "UL" in the scheduling result by the control unit 11 arrives, the UL processing unit 13 demodulates the data signal by performing predetermined signal processing on the acquired received signal. If the data signal cannot be correctly demodulated, it may be possible to improve the quality by removing interference components due to CLI from the received signal. Therefore, if the data signal cannot be correctly demodulated, the UL processing unit 13 removes the interference components. Then, the UL processing unit 13 performs demodulation processing on the received signal from which the interference components have been removed. The UL processing unit 13 outputs the data signal that has been subjected to the demodulation processing to the control unit 11.

[0027] The scheduling adjustment unit 14 adjusts scheduling to reduce self-interference occurring in antenna panels at the same site. Specifically, the scheduling adjustment unit 14 adjusts the allocation of antenna devices 20 or schedules to adjust the allocation times of resource blocks, thereby reducing self-interference occurring in antenna panels at the same site.

[0028] In this way, the scheduling adjustment unit 14 adjusts the scheduling performed by the control unit 11 so that transmission and reception are not performed at the same time using the antenna panel at the same site. The scheduling adjustment unit 14 notifies the control unit 11 of scaling information indicating the adjusted scheduling result.

[0029] The antenna device 20 includes an RF unit 21. The antenna device 20 may include multiple RF units 21. The RF unit 21 includes multiple antenna elements. As described above, an antenna panel is formed using multiple antenna elements. Therefore, the RF unit 21 includes one or more antenna panels. The RF unit 21 forms a beam using the antenna panel and performs wireless communication with the terminal device 30. The RF unit 21 wirelessly transmits a transmission signal output from the base station 10 to the terminal device 30 as a DL signal. The RF unit 21 wirelessly receives an UL signal transmitted from the terminal device 30. The RF unit 21 outputs the received UL signal to the base station 10 as a received signal.

[0030] 3 is a diagram showing an example of the configuration of a terminal device 30 in the first embodiment. The terminal device 30 includes a control unit 31, a DL processing unit 32, a UL processing unit 33, an RF unit 34, and a beam report adjustment unit 35. Note that the terminal device 30 may include multiple RF units 34.

[0031] The control unit 31 controls the operation of the terminal device 30. The control unit 31 outputs a data signal to be transmitted to the UL processing unit 33. The control unit 31 acquires the data signal output from the DL processing unit 32. The control unit 31 also outputs a beam report output from the beam report adjustment unit 35 to the UL processing unit 33.

[0032] The DL processing unit 32 acquires the received signal (DL signal) received by the RF unit 34. The DL processing unit 32 demodulates the data signal by performing predetermined signal processing on the acquired received signal. The DL processing unit 32 outputs the demodulated data signal to the control unit 31.

[0033] The UL processing unit 33 generates a transmission signal by performing predetermined signal processing on the data signal or the beam report. The UL processing unit 33 generates a transmission signal by performing modulation processing (radio frequency processing) on ​​the data signal or the beam report input from the control unit 31, for example. The UL processing unit 33 outputs the generated transmission signal to the RF unit 34.

[0034] The RF unit 34 wirelessly transmits the transmission signal output from the UL processing unit 33 as an UL signal to the antenna device 20, which is the communication partner. The RF unit 34 wirelessly receives the DL signal transmitted from the antenna device 20. The RF unit 34 outputs the received DL signal to the DL processing unit 32 as a received signal.

[0035] The beam report adjustment unit 35 generates a beam report including information on at least a beam transmitted by the connected antenna device 20. Note that the beam report adjustment unit 35 may also generate a beam report including information on a beam transmitted by one or more antenna devices 20 other than the connected antenna device 20. The beam report is a report used when changing the antenna device 20 and the beam in the base station 10. In the beam report, spatial relationship information with at least two or more antenna devices 20 may be held in a TCI (Transmission Configuration Indication) state pool set by RRC (Radio Resource Control) and a TCI state activated by MAC-CE (Medium Access Control - Control Element).

[0036] Furthermore, the beam measurement and beam report of the terminal device 30 may be performed as follows. For example, the network may return an RRC to instruct the terminal device 30 to return beam reports for multiple antenna devices 20. Alternatively, the terminal device 30 may take the initiative in returning beam reports for multiple antenna devices 20 from among high-quality beams such as L1-RSRP (Layer 1 - Reference Signal Received Power). Furthermore, when returning a beam report at the initiative of the terminal device 30, the beam report may be returned periodically, or the beam report may be returned only when a beam with better quality appears compared with the currently used beam and beam information for an antenna device 20 other than the antenna device 20 of the used beam stored in the TCI state pool.

[0037] Each antenna device 20 may be provided with a DL processing unit 12 and a UL processing unit 13 .

[0038] (Overview) Next, an overview of the first embodiment will be described using Figures 4 and 5. Figures 4 and 5 are diagrams for explaining an overview of a wireless communication system 100 in the first embodiment. In Figures 4 and 5, it is assumed that terminal devices 30-1 and 30-2 are connected to the antenna device 20-2 before scheduling adjustment. In order to prevent self-interference, the scheduling adjustment unit 14 schedules UL reception and DL transmission in time or space so that transmission and reception do not occur at the same time on antenna panels at the same site (for example, multiple antenna panels provided in the antenna device 20-2).

[0039] Specifically, if the antenna device 20 transmitting the DL signal can be changed from antenna device 20-2 to antenna device 20-3, the scheduling adjustment unit 14 schedules the transmission of the DL signal to antenna device 20-3, as shown in FIG. 4. As a result, at the same time, the UL signal is received by antenna device 20-2, and the DL signal is transmitted by antenna device 20-3. Therefore, transmission and reception do not occur from antenna panels at the same site at the same time. As a result, self-interference can be suppressed. However, if transmission and reception occur at the same time and at the same frequency, CLI occurs in the UL signal due to the DL signal transmitted from antenna device 20-3.

[0040] Furthermore, if the antenna device 20 receiving the UL signal can be changed from antenna device 20-2 to antenna device 20-1, the scheduling adjustment unit 14 schedules the UL signal to be received by antenna device 20-1, as shown in FIG. 5. As a result, at the same time, the UL signal is received by antenna device 20-1 and the DL signal is transmitted by antenna device 20-2. Therefore, transmission and reception do not occur from the antenna panel at the same site at the same time. As a result, self-interference can be suppressed. However, if transmission and reception occur at the same time and at the same frequency, CLI occurs in the UL signal due to the DL signal transmitted from antenna device 20-2.

[0041] In Figures 4 and 5, for the sake of simplicity, we have described scheduling that changes the antenna device 20 that transmits and receives, but the scheduling adjustment unit 14 may also suppress self-interference by adjusting the allocation time of resource blocks.

[0042] (Operation) Figure 6 is a flowchart showing the flow of scheduling processing performed by the base station 10 in the first embodiment. The control unit 11 of the base station 10 schedules DL signals and UL signals based on conventional technology (step S101). Based on the scheduling result by the control unit 11, the scheduling adjustment unit 14 determines whether there is a combination of transmission and reception at the same time on an antenna panel at the same site (step S102). That is, based on the scheduling result by the control unit 11, the scheduling adjustment unit 14 determines whether there is a combination of UL reception and DL transmission times overlapping within the same antenna device 20.

[0043] The scheduling adjustment unit 14 determines that there is a combination of transmission and reception at the same time on an antenna panel at the same site when there is a combination of UL reception and DL transmission at the same time on the same antenna device 20. On the other hand, the scheduling adjustment unit 14 determines that there is no combination of transmission and reception at the same time on an antenna panel at the same site when there is no combination of UL reception and DL transmission at the same time on the same antenna device 20. If the scheduling adjustment unit 14 determines that there is no combination of transmission and reception at the same time on an antenna panel at the same site (step S102-NO), the base station 10 ends the processing of FIG.

[0044] On the other hand, if the scheduling adjustment unit 14 determines that there is a combination of transmission and reception at the same time using antenna panels at the same site (step S102—YES), the scheduling adjustment unit 14 determines whether to perform SI removal processing (step S103). For example, the scheduling adjustment unit 14 may determine to perform SI removal processing when there is a combination of UL reception and DL transmission at the same time using the same antenna device 20. The SI removal processing means that the scheduling adjustment unit 14 adjusts the schedule to suppress self-interference.

[0045] Note that even if there is a combination in which UL reception and DL transmission are performed at the same time, the scheduling adjustment unit 14 may determine not to perform SI removal processing if the impact of quality degradation due to self-interference is expected to be small. Here, examples of situations in which the impact of quality degradation due to self-interference is expected to be small include cases in which the antenna panels at the same site are oriented in opposite directions (i.e., when multiple antenna panels provided on the same antenna device 20 are oriented in opposite directions), when there is obstruction between the antenna panels that transmit and receive, and when the impact of interference waves is small. In this way, the scheduling adjustment unit 14 may determine whether the impact of quality degradation due to self-interference is expected to be small based on the physical arrangement of the multiple antenna panels provided on the antenna device 20, or may determine based on actual CLI measurement results. When making a determination based on actual CLI measurement results, a CLI table in which CLI measurement results for all beam pairs are registered can be created to determine antenna panel pairs that are expected to be out of reach of interference waves or to be minimally affected by interference waves.

[0046] If the scheduling adjustment unit 14 determines not to perform SI removal processing (step S103-NO), the base station 10 ends the processing in Fig. 6. On the other hand, if the scheduling adjustment unit 14 determines to perform SI removal processing (step S103-YES), the scheduling adjustment unit 14 adjusts the scheduling so that transmission and reception are not performed using antenna panels at the same site at the same time (step S104). The antenna panels at the same site refer to antenna panels provided in the same antenna device 20. Two scheduling adjustment methods will be specifically described below.

[0047] (First Scheduling Adjustment Method) The scheduling adjustment unit 14 may adjust scheduling so that resource blocks are preferentially allocated to DL signals transmitted by or received from different antenna devices 20, so that the reception times of UL signals and transmission times of DL signals do not overlap on antenna panels at the same site. An example will be described below with reference to FIG. 7. FIG. 7 is a diagram showing an example of scheduling adjustment by changing resource block allocation in the first embodiment. As shown in FIG. 7, as a result of scheduling by the control unit 11, it is assumed that UL reception and DL transmission are performed at the same time by antenna device 20-1 at timing (2). Therefore, the scheduling adjustment unit 14 determines the destination based on the beam report transmitted from the terminal device 30.

[0048] Specifically, the scheduling adjustment unit 14 changes the allocation time of resource blocks for causing antenna device 20-1 to perform DL transmission and the allocation time of resource blocks for causing antenna device 20-3 to perform DL transmission. For example, the scheduling adjustment unit 14 prioritizes the resource blocks allocated for causing antenna device 20-3 to perform DL transmission at timing (3), and allocates resource blocks for causing antenna device 20-3 to perform DL transmission at timing (2). Then, the scheduling adjustment unit 14 allocates resource blocks for causing antenna device 20-1 to perform DL transmission at timing (3), which were allocated for causing antenna device 20-1 to perform DL transmission at timing (2).

[0049] As a result, at timing (2), UL reception is performed by antenna device 20-1, and DL transmission is performed by antenna device 20-3. Furthermore, at timing (3), UL reception is performed by antenna device 20-2, and DL transmission is performed by antenna device 20-1. Note that this allocation is just one example, and the scheduling adjustment unit 14 can adjust the resource block allocation times so that transmission and reception do not occur at the same time on antenna panels at the same site.

[0050] (Second Scheduling Adjustment Method) If it is possible to change the antenna device 20 for UL reception or DL ​​transmission so that the reception time of a UL signal and the transmission time of a DL signal do not overlap on the antenna panel at the same site, the scheduling adjustment unit 14 may adjust the scheduling to change either the antenna device 20. An example will be described below with reference to FIG. 8. FIG. 8 is a diagram showing an example of scheduling adjustment by changing the antenna device 20 in the first embodiment. As shown in FIG. 8, as a result of scheduling by the control unit 11, it is assumed that UL reception and DL transmission are performed at the same time by the antenna device 20-1 at timing (2). Therefore, the scheduling adjustment unit 14 determines the destination of the change based on the beam report transmitted from the terminal device 30.

[0051] Specifically, the scheduling adjustment unit 14 changes the target for UL reception or DL ​​transmission. For example, the scheduling adjustment unit 14 assigns antenna device 20-2 as the antenna device 20 that performs UL reception at timing (2). That is, the scheduling adjustment unit 14 changes the antenna device 20 that performs UL reception at timing (2) from antenna device 20-1 to antenna device 20-2.

[0052] As a result, at timing (2), UL reception is performed by antenna device 20-2, and DL transmission is performed by antenna device 20-1. Note that this allocation is just an example, and the scheduling adjustment unit 14 can adjust the allocation of antenna devices 20 so that transmission and reception are not performed at the same time by antenna panels at the same site.

[0053] The scheduling adjustment unit 14 selects a change in the antenna device 20 from candidates for the antenna device 20 and beam set stored in, for example, the TCI state pool. Therefore, in order to have two or more candidates for the antenna device 20, the beam report adjustment unit 35 of the terminal device 30 needs to return beam reports of one or more antenna devices 20 other than the connected antenna device 20 to the base station 10. The TCI state pool is configured to store spatial relationship information with at least two or more antenna devices 20. However, this does not apply when the quality of the beam set other than the connected antenna device 20 is extremely poor compared to the beam of the connected antenna device 20, for example, when the power is below a certain threshold.

[0054] The scheduling adjustment unit 14 notifies the control unit 11 of the adjusted scheduling information (step S105). The control unit 11 notifies the DL processing unit 12 and the UL processing unit 13 of the scheduling information notified from the scheduling adjustment unit 14. As a result, the DL processing unit 12 and the UL processing unit 13 operate based on the scheduling information notified from the control unit 11.

[0055] According to the wireless communication system 100 configured as described above, the base station 10 is provided with a scheduling adjustment unit 14 that adjusts the schedule of combinations of antenna devices 20 that transmit and receive at the same time, among multiple antenna devices 20 that are distributed and arranged so that the combinations suppress interference that occurs between the uplink and downlink, including self-interference, and a control unit 11 that controls the operation of each antenna device 20 based on the results adjusted by the scheduling adjustment unit 14.

[0056] In this way, the scheduling adjustment unit 14 adjusts the schedule so that the combination suppresses interference occurring between the uplink and downlink at the same time, thereby reducing the degradation of transmission quality due to CLI (especially self-interference).

[0057] Furthermore, the scheduling adjustment unit 14 adjusts the schedule so that transmission and reception are not performed at the same time using the same antenna device 20. This prevents transmission of DL signals and reception of UL signals from antenna panels at the same site (multiple antenna panels provided in the same antenna device 20). Therefore, self-interference does not occur. This makes it possible to reduce degradation of transmission quality due to CLI (especially self-interference).

[0058] (Second Embodiment) In the first embodiment, a configuration for suppressing degradation of transmission quality due to self-interference was described. In the second embodiment, a configuration for suppressing degradation of transmission quality due to CLI occurring between antenna devices will be described. The system configuration in the second embodiment is the same as that in the first embodiment. In the second embodiment, the configuration of the base station is different from that in the first embodiment. The following description will focus on the differences from the first embodiment.

[0059] In the second embodiment, the base station generates a CLI table in which the CLI measurement results of all beam pairs are registered by measuring the CLI of each beam pair within the same antenna device and measuring the CLI of each beam pair between each antenna device 20. The base station then references the generated CLI table and allocates resource blocks (RBs) preferentially to antenna device and beam pairs that are least susceptible to CLI-related degradation of transmission quality, thereby suppressing quality degradation due to CLI. Alternatively, the base station in the second embodiment suppresses quality degradation due to CLI by changing the antenna device or beam for UL reception or DL ​​transmission, if possible. A specific configuration for implementing the above process will be described below.

[0060] (Device Configuration) Fig. 9 is a diagram showing a configuration example of a base station 10a and an antenna device 20 in the second embodiment. The base station 10a includes a control unit 11, a DL processing unit 12, a UL processing unit 13, a scheduling adjustment unit 14a, and a CLI table generation unit 15a. The base station 10a differs in configuration from the base station 10 in that it includes the scheduling adjustment unit 14a instead of the scheduling adjustment unit 14, and in that it newly includes a CLI table generation unit 15a. The rest of the configuration of the base station 10a is the same as that of the base station 10.

[0061] The CLI table generator 15a measures the CLI of each beam pair within the same antenna device 20, and measures the CLI of each beam pair between each antenna device 20. For example, if each antenna device 20 can use beam 1 and beam 2, the following two CLIs are measured when measuring the CLI of each beam pair within the same antenna device 20: - When beam 1 is used for transmission and beam 2 is used for reception - When beam 2 is used for transmission and beam 1 is used for reception

[0062] Furthermore, when measuring the CLI of each beam pair between each antenna device 20, the following four CLIs are measured: - When a certain antenna device 20 (e.g., antenna device 20-1) uses beam 1 for transmission and another antenna device 20 (e.g., antenna device 20-2) uses beam 1 for reception - When a certain antenna device 20 (e.g., antenna device 20-1) uses beam 1 for transmission and another antenna device 20 (e.g., antenna device 20-2) uses beam 2 for reception - When a certain antenna device 20 (e.g., antenna device 20-1) uses beam 2 for transmission and another antenna device 20 (e.g., antenna device 20-2) uses beam 1 for reception - When a certain antenna device 20 (e.g., antenna device 20-1) uses beam 2 for transmission and another antenna device 20 (e.g., antenna device 20-2) uses beam 2 for reception

[0063] Note that the CLI measurements shown above are for cases where each antenna device 20 can use two beams, beam 1 and beam 2, and the CLI pattern measured varies depending on the number of beams available to each antenna device 20.

[0064] The CLI table generator 15a generates a CLI table based on the CLI measurement results. An example of the CLI table generated by the CLI table generator 15a is shown in FIG. 10. FIG. 10 is a diagram showing an example of the CLI table in the second embodiment. As shown in FIG. 10, the CLI measurement results for each antenna device 20 are registered in the CLI table. For example, FIG. 10 shows that the CLI is "CLI11-12" when beam 1 is used for transmission in the first antenna panel provided in the RF unit 21 of the antenna device 20-1 and beam 2 is used for reception in the second antenna panel provided in the RF unit 21.

[0065] Note that the CLI measurement may be performed within each antenna device 20, and the CLI table generator 15a may generate the CLI table based on the content notified from each antenna device 20.

[0066] The scheduling adjustment unit 14a performs scheduling adjustment to reduce CLI occurring between the antenna devices 20. Specifically, the scheduling adjustment unit 14a adjusts the allocation of the antenna devices 20 or performs scheduling to adjust the allocation times of resource blocks, thereby reducing CLI occurring between the antenna devices 20.

[0067] In this way, the scheduling adjustment unit 14a adjusts the scheduling performed by the control unit 11 to a combination of antenna devices 20 and beams that are less affected by quality degradation due to CLI. A less affected quality degradation due to CLI means that the CLI is less than a threshold. The scheduling adjustment unit 14a notifies the control unit 11 of scaling information indicating the adjusted scheduling result.

[0068] The scheduling adjustment unit 14a may schedule UL reception and DL transmission so as to pair antenna devices 20 and beams that have minimal quality degradation due to CLI, based on the CLI table generated by the CLI table generation unit 15. The scheduling adjustment unit 14a notifies the control unit 11 of scaling information indicating the adjusted scheduling result.

[0069] 11 is a flowchart showing the flow of the CLI table update process performed by the base station 10 in the second embodiment. The CLI table generation unit 15a determines whether or not a CLI table update condition is satisfied (step S201). The CLI table update condition is a condition for updating the information registered in the CLI table, and may be, for example, an external update instruction or a predetermined timing.

[0070] If the CLI table generator 15a determines that the CLI table update condition is not satisfied (step S201—NO), the CLI table generator 15a terminates the processing of Fig. 9. On the other hand, if the CLI table generator 15a determines that the CLI table update condition is satisfied (step S201—YES), the CLI table generator 15a determines whether interference from sources other than the target of estimation is less than a threshold (step S202). Here, the target of estimation is the target for which CLI measurement is performed.

[0071] The CLI table generator 15a determines that interference other than the target of estimation is below a threshold based on the transmission signal information shared by the DL processing unit 12 and the reception signal information shared by the UL processing unit 13 when the interference other than the target of estimation is below a threshold, for example, when transmission and reception other than the target of estimation are below a threshold. On the other hand, the CLI table generator 15a determines that interference other than the target of estimation is not below a threshold when the interference other than the target of estimation is not below a threshold, for example, when transmission and reception other than the target of estimation are equal to or greater than the threshold. The transmission signal information includes information indicating the output destination of the transmission signal transmitted from the DL processing unit 12 (e.g., the antenna panel of the antenna device 20) and the transmission timing of the transmission signal. The reception signal information includes information indicating the output source of the reception signal acquired by the UL processing unit 13 (e.g., the antenna panel of the antenna device 20) and the reception timing of the reception signal.

[0072] If the CLI table generator 15a determines that the interference from sources other than the target of estimation is not less than the threshold (step S202—NO), the CLI table generator 15a terminates the processing of FIG. 9 . On the other hand, if the CLI table generator 15a determines that the interference from sources other than the target of estimation is less than the threshold (step S202—YES), the CLI table generator 15a measures the CLI of the target of estimation (step S203). Here, the CLI is measured by measuring the received power of, for example, SSB or CSI-RS for each antenna device 20 and each beam pair. Note that, if measurement is possible, the CLI table generator 15a also measures the CLI between different beams within the same antenna device 20. The CLI table generator 15a also measures beams formed by the cooperation of multiple antenna devices 20.

[0073] The CLI table generator 15a may perform multiple measurements of the same CLI and average the results, or may correct the measurement results by removing outliers. The CLI table generator 15a then updates the CLI table based on the measurement results (step S204). Here, the CLI table generator 15a normalizes the CLI measurement results to the CLI for the same transmission power based on DL signal transmission power information shared by the DL processing unit 12, and stores the normalized results. Furthermore, when the CLI stored in the CLI table is compared with the measurement results and the values ​​are different, the CLI table generator 15a may cancel updating the CLI table or perform averaging based on information on past CLI measurement results, for example.

[0074] By using the CLI table generated in this way, it is possible to confirm a combination of antenna devices 20 and beams that will not cause quality degradation due to CLI.

[0075] 12 is a flowchart showing the flow of scheduling processing performed by the base station 10 in the second embodiment. In Fig. 12, the same processes as those in Fig. 6 are denoted by the same reference numerals as in Fig. 6, and the description thereof will be omitted. After the processing of step S101, the scheduling adjustment unit 14a determines whether or not to perform CLI mitigation processing (step S301).

[0076] Specifically, the scheduling adjustment unit 14a determines to perform CLI mitigation processing when the beam pair of the antenna device 20 that receives UL signals and transmits DL signals scheduled by the control unit 11 is a pair that is greatly affected by CLI. Here, the influence of CLI is large when, for example, the CLI of the corresponding antenna device 20 and beam pair in the CLI table is equal to or greater than a certain threshold.

[0077] On the other hand, the scheduling adjustment unit 14a determines not to perform CLI mitigation processing if all beam pairs of the antenna device 20 that receive UL signals and transmit DL signals scheduled by the control unit 11 are not pairs that are significantly affected by CLI (if the impact of quality degradation due to CLI is small).

[0078] If the scheduling adjustment unit 14a determines not to perform CLI mitigation processing (step S301—NO), the scheduling adjustment unit 14a terminates the processing of Fig. 12. On the other hand, if the scheduling adjustment unit 14a determines to perform CLI mitigation processing (step S301—YES), the scheduling adjustment unit 14a adjusts the scheduling so as to reduce quality degradation due to CLI (step S302).

[0079] Specifically, the scheduling adjustment unit 14a refers to the CLI table and adjusts the scheduling so that resource blocks are preferentially allocated to a combination of an antenna device 20 and a beam that suffers little quality degradation due to CLI. Alternatively, the scheduling adjustment unit 14a adjusts the scheduling so that the antenna device 20 or beam for UL reception or DL ​​transmission can be changed if it is possible. Here, the beam may be formed by one antenna device 20, or may be formed by cooperation of multiple antenna devices 20. Then, the processing of step S105 is performed.

[0080] According to the wireless communication system 100 of the second embodiment configured as above, it is possible to obtain the same effects as those of the first embodiment.

[0081] Furthermore, in the wireless communication system 100 according to the second embodiment, the base station 10a includes a CLI table generator 15 that generates a CLI table by measuring the CLI of each beam pair within the same antenna device 20 and measuring the CLI of each beam pair between the antenna devices 20. The scheduling adjuster 14a refers to the CLI table and adjusts the schedule to create a combination that suppresses CLI. This enables simultaneous reception of UL signals and transmission of DL signals with a combination that can suppress CLI between the antenna devices 20. Therefore, self-interference does not occur, and the impact of CLI is reduced. This makes it possible to reduce not only self-interference but also degradation of transmission quality due to CLI occurring between the antenna devices 20.

[0082] Third Embodiment In a third embodiment, a configuration will be described in which a base station adjusts the transmission power of a DL signal so as to reduce the influence of quality degradation due to CLI.

[0083] 13 is a diagram showing an example of the configuration of a base station 10b and an antenna device 20 in the third embodiment. The base station 10b includes a control unit 11b, a DL processing unit 12b, an UL processing unit 13, a scheduling adjustment unit 14a, a CLI table generation unit 15a, and a power adjustment unit 16b. The base station 10b differs in configuration from the base station 10a in that it includes a control unit 11b and a DL processing unit 12b instead of the control unit 11 and the DL processing unit 12, and in that it newly includes a power adjustment unit 16b. The rest of the configuration of the base station 10b is the same as that of the base station 10a. The following description will focus on the differences from the base station 10a.

[0084] When transmitting and receiving using an antenna device 20 and beam set that are significantly affected by CLI, the power adjustment unit 16b instructs the control unit 11b to reduce the transmission power of the DL signal based on the CLI table so that the CLI power is below a threshold that does not cause quality degradation.

[0085] The control unit 11b controls the operation of the base station 10b. The control unit 11b performs the same processing as the control unit 11 in the second embodiment. Furthermore, in response to an instruction from the power adjustment unit 16b, the control unit 11b instructs the DL processing unit 12b to control the transmission power of a DL signal to the antenna device 20 whose transmission power is to be controlled.

[0086] The DL processing unit 12b performs the same processing as the control unit 11 in the second embodiment. Furthermore, in response to an instruction from the control unit 11b, the DL processing unit 12b includes, in the transmission signal to be transmitted to the antenna device 20 whose transmission power is to be controlled, an instruction to transmit the DL signal at the transmission power instructed by the control unit 11b.

[0087] Fig. 14 is a flowchart showing the flow of scheduling processing performed by the base station 10b in the third embodiment. In Fig. 14, the same processes as in Fig. 12 are denoted by the same reference numerals as in Fig. 12, and descriptions thereof will be omitted. The scheduling adjustment unit 14b performs scheduling adjustment in the same manner as in the second embodiment. That is, the scheduling adjustment unit 14b executes the processes from step S101 to step S304. The scheduling adjustment unit 14b determines whether quality degradation due to CLI remains after the scheduling adjustment (step S401).

[0088] Whether quality degradation due to CLI remains is determined based on whether or not a bit error occurs when the received signal is demodulated, and whether or not the received SINR (Signal to Interference plus Noise Ratio) is equal to or less than a certain threshold that prevents bit errors from occurring during demodulation. For example, the scheduling adjustment unit 14b may determine that quality degradation due to CLI remains if a bit error occurs when the received signal is demodulated, and may determine that quality degradation due to CLI does not remain if no bit error occurs. Furthermore, the scheduling adjustment unit 14b may determine that quality degradation due to CLI remains if the received SINR is higher than a certain threshold, and may determine that quality degradation due to CLI does not remain if the received SINR is equal to or less than the certain threshold.

[0089] If the scheduling adjustment unit 14b determines that there is no remaining quality degradation due to CLI (step S401—NO), the base station 10b ends the processing in Fig. 14. On the other hand, if the scheduling adjustment unit 14b determines that there is remaining quality degradation due to CLI (step S401—YES), the power adjustment unit 16b refers to the CLI table and adjusts the transmission power of the DL signal to be reduced so that the CLI power is equal to or less than a threshold that does not cause quality degradation (step S402).

[0090] Thereafter, the scheduling adjustment unit 14b notifies the control unit 11b of the adjusted scheduling information. Furthermore, the power adjustment unit 16b notifies the control unit 11b of the adjusted transmission power information (step S403). The control unit 11b notifies the DL processing unit 12b and the UL processing unit 13 of the scheduling information notified from the scheduling adjustment unit 14. Furthermore, the control unit 11b notifies the DL processing unit 12b of the transmission power information notified from the power adjustment unit 16b.

[0091] The DL processing unit 12b and the UL processing unit 13 operate based on the scheduling information notified by the control unit 11. Furthermore, the DL processing unit 12b transmits a transmission signal including information indicating the transmission power notified by the control unit 11. As a result, the antenna device 20 that receives the transmission signal transmitted from the DL processing unit 12b transmits the DL signal at the transmission power indicated by the information indicating the transmission power included in the transmission signal.

[0092] According to the wireless communication system 100 of the third embodiment configured as above, it is possible to obtain the same effects as those of the second embodiment.

[0093] Furthermore, in the wireless communication system 100 according to the third embodiment, the base station 10b includes a power adjustment unit 16b that adjusts the transmission power of the DL signal. If quality degradation remains based on the scheduling result by the scheduling adjustment unit 14a, the power adjustment unit 16b adjusts the transmission power of the DL signal so as to reduce the quality degradation. This makes it possible to suppress CLI for UL reception due to transmission of the DL signal.

[0094] (Variation) Based on the power adjustment result of the power adjustment unit 16b, the scheduling adjustment unit 14b may perform scheduling to ensure diversity with other antenna devices 20, for example, in order to suppress quality degradation caused by reduced transmission power. In this case, the control unit 11b performs control to ensure diversity with antenna devices 20 at other sites. In this way, the base station 10b may adjust the transmission power and diversity of the DL signal, and may also perform adjustments to maximize, for example, resource block utilization efficiency and system transmission capacity.

[0095] Some or all of the functional units of the base stations 10, 10a, 10b and the terminal device 30 are realized as software by a processor such as a CPU (Central Processing Unit) executing a program stored in a storage device having a non-volatile storage medium (non-transitory storage medium) and a storage unit. The program may be recorded on a computer-readable non-transitory storage medium. Examples of computer-readable non-transitory storage media include portable media such as flexible disks, magneto-optical disks, ROMs (Read Only Memory), and CD-ROMs (Compact Disc Read Only Memory), and storage devices such as hard disks built into computer systems.

[0096] Some or all of the functional units of the base stations 10, 10a, 10b and the terminal device 30 may be realized using hardware including electronic circuits (electronic circuits or circuitry) using, for example, an LSI (Large Scale Integrated circuit), an ASIC (Application Specific Integrated Circuit), a PLD (Programmable Logic Device), or an FPGA (Field Programmable Gate Array).

[0097] The base stations 10, 10a, and 10b in the above-described embodiments can be interpreted as a "radio base station," a "NodeB," an "eNodeB," a "gNodeB," an "access point," a "cell," a "macrocell," a "small cell," a "femtocell," and a "picocell."

[0098] The antenna device 20 in the above-described embodiment can be read as a "Transmission and Reception Point (TRP)", a "Remote Radio Unit (RRU)", a "Radio Unit (RU)", a "Distributed Antenna (DA)", a "Panel", a "TP (Transmission Point)", and an "RP (Reception Point)".

[0099] Although an embodiment of the present invention has been described above in detail with reference to the drawings, the specific configuration is not limited to this embodiment, and includes designs within the scope of the gist of the present invention.

[0100] The present invention can be applied to a wireless communication system in which downlink and uplink transmission and reception are performed at the same time.

[0101] 10, 10a, 10b... base station, 11, 11b... control unit, 12, 12b... DL processing unit, 13... UL processing unit, 14, 14a... scheduling adjustment unit, 15a... CLI table generation unit, 16b... power adjustment unit, 20, 20-1 to 20-3... antenna devices, 21, 21-1 to 21-3... RF unit, 30... terminal device, 31... control unit, 32... DL processing unit, 33... UL processing unit, 34... RF unit, 35... beam report adjustment unit

Claims

1. A base station comprising: a scheduling adjustment unit that adjusts the schedule of combinations of antenna devices that transmit and receive at the same time, among multiple antenna devices that are distributed and arranged so that the combinations suppress interference that occurs between uplinks and downlinks, including self-interference; and a control unit that controls the operation of each antenna device based on the results of adjustment by the scheduling adjustment unit.

2. The base station according to claim 1, wherein the scheduling adjustment unit adjusts the schedule so that transmission and reception are not performed at the same time using the same antenna device.

3. The base station according to claim 1, further comprising a table generation unit that generates an interference table in which the interference measurement results for each beam set are registered by measuring the interference of each beam set within the same antenna device and measuring the interference of each beam set between each antenna device, and wherein the scheduling adjustment unit refers to the interference table and adjusts the schedule to create a combination that suppresses the interference.

4. The base station according to claim 3, further comprising a power adjustment unit that adjusts transmission power in the downlink, wherein, if quality degradation remains, the power adjustment unit adjusts the transmission power in the downlink to reduce the quality degradation based on the result of schedule adjustment to achieve a combination that suppresses the interference.

5. The base station according to claim 1, wherein the scheduling adjustment unit adjusts the schedule by adjusting the allocation time of resource blocks.

6. The base station according to claim 1, wherein the scheduling adjustment unit adjusts the schedule by adjusting the allocation of antenna devices.

7. A terminal device comprising a beam report adjustment unit that transmits a beam report containing information about beams transmitted by a connected antenna device and one or more other unconnected antenna devices among a plurality of antenna devices that are distributedly arranged, to a base station that accommodates the plurality of antenna devices via the connected antenna device.

8. A communication method performed by a base station that performs wireless communication with a terminal device via multiple antenna devices that are distributed in a way that adjusts the schedule of combinations of antenna devices that transmit and receive at the same time from among the multiple antenna devices that are distributed in a way that suppresses interference that occurs between uplinks and downlinks, including self-interference, and controls the operation of each antenna device based on the adjusted results.

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