Base station, wireless communication system, and wireless communication method

Abstract

This base station comprises: a transfer function estimation unit that estimates a transfer function of a transmission path between a plurality of dispersedly arranged antenna devices or another base station and a host device; and an interference removal unit that, on the basis of the transfer function estimated by the transfer function estimation unit and a replica signal of a second signal of a device with which interference is to occur and which transmits the second signal at the reception timing of a first signal, removes an interference component from the received first signal.　

Description

Base station, wireless communication system, and wireless communication method

[0001] The present invention relates to a base station, a wireless communication system, and a wireless 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 systems can be achieved. However, degradation of transmission quality due to cross link interference (CLI), which is interference between the uplink and downlink, 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 simultaneously between multiple terminal devices that have formed links. FIG. 8 is a diagram for explaining the conventional problem. The wireless communication system S shown in FIG. 8 includes multiple base stations 1-1 to 1-2 and multiple terminal devices 2-1 to 2-3. FIG. 9 also shows the transmission and reception timings assigned to the terminal devices 2-1 to 2-3 in the wireless communication system S shown in FIG. 8.

[0005] Consider a situation in which, as shown in Figure 8, at the same time (the time indicated as "present" in Figure 9), base station 1-1 transmits a DL signal to terminal device 2-1, terminal device 2-3 transmits a UL signal to base station 1-2, and base station 1-2 transmits a DL signal to terminal device 2-2. Under such circumstances, CLI occurs in base station 1-2 due to the DL signal transmitted by base station 1-1. Furthermore, CLI also occurs due to receiving reflected waves of the DL signal transmitted by base station 1-2 itself.

[0006] In conventional technology, a base station has an interference measurement function using interference measurement signals transmitted from other base stations, and reduces CLI by using information indicating the measured CLI to schedule UL transmissions so as to minimize degradation of transmission quality due to CLI (see, for example, Non-Patent Documents 1 to 3; 3GPP (Generation Partnership Project) is a registered trademark).

[0007] NTT DOCOMO, “Views on Rel. 19 evolution of NR duplex operation”, 3GPP TSG RAN WG1 #101, RP-232074, Sept. 2023.NTT DOCOMO, “New WID: Evolution of NR duplex operation: Sub-band full duplex (SBFD)”, 3GPP TSG RAN WG1 #102, RP-234035, Dec. 2023.NTT DOCOMO, “Discussion on CLI handling for sub-band full duplex (SBFD)”, 3GPP TSG RAN WG1 #116, R1-2401118, March 2024.

[0008] However, interference control based on scheduling may cause delays in resource allocation. Furthermore, a dedicated signal needs to be transmitted for interference measurement, resulting in the use of unnecessary resources. As a result, the resource utilization efficiency of the wireless communication system is reduced. Furthermore, even if the CLI measurement results are used, the CLI cannot be removed by signal processing because the DL signals transmitted from each base station are unknown to each other. Thus, conventionally, there has been a problem in that it is not possible to reduce the CLI occurring in the FD method or the SBFD method while improving the resource utilization efficiency of the wireless communication system. Note that this problem is not limited to the FD method or the SBFD method, but occurs when downlink and uplink transmission and reception are performed at the same time.

[0009] In view of the above circumstances, an object of the present invention is to provide a technique that can reduce interference between uplink and downlink while improving resource utilization efficiency in a wireless communication system.

[0010] One aspect of the present invention is a base station comprising: a transfer function estimation unit that estimates a transfer function of a transmission path between the base station and a plurality of dispersedly arranged antenna devices or other base stations; and an interference removal unit that removes interference components from a received first signal based on the transfer function estimated by the transfer function estimation unit and a replica signal of the second signal of an interfering device that is transmitting a second signal at the reception timing of the first signal.

[0011] One aspect of the present invention is a wireless communication system comprising a first base station and a plurality of antenna devices or a second base station arranged in a distributed manner, wherein the plurality of antenna devices or the second base station transmits a second signal to a terminal device and shares a replica signal of the transmitted second signal with the first base station, and the first base station comprises a transfer function estimation unit that estimates a transfer function of a transmission path between the plurality of antenna devices or the second base station and the first base station, and an interference removal unit that removes interference components from the received first signal based on the transfer function estimated by the transfer function estimation unit and one of the plurality of antenna devices that is transmitting the second signal at the reception timing of the first signal or the replica signal of the second signal shared from the second base station.

[0012] One aspect of the present invention is a wireless communication method that estimates a transfer function of a transmission path between a plurality of dispersedly arranged antenna devices or another base station and the device itself, and removes interference components from a received first signal based on the estimated transfer function and a replica signal of the second signal of an interfering device that is transmitting a second signal at the timing of receiving the first signal.

[0013] The present invention makes it possible to reduce interference between the uplink and downlink while improving the resource utilization efficiency of a wireless communication system.

[0014] 1 is a diagram showing an example of the configuration of a wireless communication system in an embodiment. FIG. 2 is a diagram showing an example of the configuration of a base station and an antenna device in an embodiment. FIG. 3 is a diagram showing an example of transmission and reception in a wireless communication system in an embodiment. FIG. 4 is a diagram showing timings of transmission and reception assigned to a terminal device in the wireless communication system shown in FIG. 3. FIG. 5 is a diagram showing an example of information buffered in a base station and an antenna device. FIG. 6 is a flowchart showing the flow of processing in a base station in an embodiment. FIG. 7 is a diagram for explaining a conventional problem. FIG. 8 is a diagram showing timings of transmission and reception assigned to a terminal device in the wireless communication system shown in FIG.

[0015] Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

[0016] 1 is a diagram showing an example of the configuration of a wireless communication system 100 according to an embodiment. The wireless communication system 100 is, for example, a distributed antenna system. The wireless communication system 100 includes one or more base stations 10 and a plurality of antenna devices 20. The plurality of antenna devices 20 are accommodated by the same base station 10. That is, in the wireless communication system 100, one base station 10 includes a plurality of antenna devices 20. The plurality of antenna devices 20 are arranged in different spatial locations.

[0017] One base station 10 and each antenna device 20 are connected via a wire (for example, optical fiber). Note that, although Fig. 1 shows a configuration in which the wireless communication system 100 includes one base station 10 and two antenna devices 20-1 to 20-2, the number of base stations 10 and antenna devices 20 included in the wireless communication system 100 is not particularly limited.

[0018] The wireless communication system 100 in this embodiment employs either the FD method or the SBFD method, and therefore, in the wireless communication system 100, communication is performed on the uplink and the downlink at the same time.

[0019] The base station 10 performs wireless communication with the terminal device 30 via an antenna provided inside the base station 10 or the antenna device 20. The terminal device 30 is a user terminal (UE: User Equipment), and is, for example, a smartphone terminal or a tablet terminal. The terminal device 30 performs wireless communication with the base station 10 via an antenna in a cell or the antenna device 20. In the following description, the direction from the base station 10 or the antenna device 20 toward the terminal device 30 is referred to as the downlink direction, and the direction from the terminal device 30 toward the base station 10 or the antenna device 20 is referred to as the uplink direction.

[0020] The antenna device 20 wirelessly transmits a signal to be transmitted (hereinafter referred to as a "transmission signal") output from the base station 10 as a DL signal (second signal) to the terminal device 30. The antenna device 20 receives a UL signal (first signal) wirelessly transmitted from the terminal device 30.

[0021] Next, specific configurations of the base station 10 and the antenna device 20 will be described. FIG. 2 is a diagram showing an example of the configuration of the base station 10 and the antenna device 20 in an embodiment. The base station 10 includes a baseband unit 11 and an RF unit 12. The baseband unit 11 performs signal processing on a transmission signal or a received UL signal (hereinafter referred to as a "received signal"). The baseband unit 11 transmits the processed transmission signal to the RF unit 12 or the antenna device 20. The RF unit 12 transmits the processed transmission signal as a DL signal to the terminal device 30 by radio via one or more antennas. The baseband unit 11 removes interference components (CLI) from the received signal.

[0022] The baseband unit 11 includes a transmission unit 111, a DL processing unit 112, a delay acquisition unit 113, a transfer function estimation unit 114, an interference removal unit 115, and a UL processing unit 116.

[0023] The transmission unit 111 transmits data signals to and from a higher-level device (not shown) for the base station 10. The transmission unit 111 outputs data signals transmitted from the higher-level device (not shown) to the DL processing unit 112. The transmission unit 111 transmits data signals output from the UL processing unit 116 to the higher-level device (not shown).

[0024] The DL processing unit 112 generates a transmission signal by performing predetermined signal processing on the data signal. For example, the DL processing unit 112 generates the transmission signal by performing modulation processing (radio frequency processing) on ​​the data signal input from the transmission unit 111. The DL processing unit 112 outputs the generated transmission signal to the RF unit 12 or the antenna device 20.

[0025] The delay acquisition unit 113 acquires the delay time (delay time of the wired section + delay time of the wireless section) of the propagation path between the base station 10 and each antenna device 20. The delay acquisition unit 113 may acquire the delay time, for example, by comparing the transmission time at which a transmission signal is transmitted from the DL processing unit 112 in the base station 10 with the reception time at which the reception signal is received by the delay acquisition unit 113, or by comparing the reception time with a timestamp included in the transmission signal, or by calculating the correlation between the demodulated signal and a replica after demodulating the received signal, or by measuring the propagation delay of the wireless section in each antenna device 20 and adding the delay time of the wired section between the base station 10 and the antenna device 20 to the measurement result. Information on the delay time measured by the delay acquisition unit 113 is stored in a buffer (not shown).

[0026] The transfer function estimation unit 114 estimates the transfer function of the propagation path (propagation path of the wired section + wireless section) between the base station 10 and each antenna device 20. The transfer function is estimated using the received signal and replicas of the transmission signals of the base station 10 and each antenna device 20 (hereinafter referred to as "replica signals") shared by the DL processing unit 112. Here, the replica signals are buffered by the DL processing unit 112, and when the signals are received, they are shared by the DL processing unit 112 with the delay acquisition unit 113, the transfer function estimation unit 114, and the interference removal unit 115. The transfer function estimation unit 114 estimates the transfer function, for example, by dividing the replica signal from the received signal. A typical transfer function is estimated using a DMRS (DeModulation Reference Signal) signal or the like and interpolated between the DMRSs. However, in the present invention, the transfer function may be estimated using replica information of all symbols. Here, the transfer function includes the influence of the wired section between the base station 10 and each antenna device 20 in addition to the influence of the wireless section between each antenna device 20, but for example, the transfer function of the wired section may be measured in advance and the estimated transfer function may be divided by the transfer function of the wired section. Information on the transfer function estimated by the transfer function estimation unit 114 is stored in a buffer (not shown).

[0027] The base station 10 stores in a buffer the replica signals of the base station 10 itself and each of the antenna devices 20. When delay measurement is performed within each antenna device 20, each antenna device 20 stores the replica signal of its own device in a buffer (not shown).

[0028] The interference removal unit 115 acquires a received signal (UL signal) received by the RF unit 12 or the antenna device 20. The interference removal unit 115 removes interference components from the acquired received signal using a replica signal stored in a buffer (not shown) and a transfer function. The interference removal unit 115 removes interference components from the received signal in response to an instruction from the UL processing unit 116. The interference removal unit 115 removes interference components from the received signal in response to an instruction from the UL processing unit 116 when, for example, the UL processing unit 116 has not performed demodulation processing correctly.

[0029] The UL processing unit 116 acquires a received signal (UL signal) received by the RF unit 12 or the antenna device 20. The UL processing unit 116 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 UL processing unit 116 cannot correctly demodulate the data signal, it instructs the interference removal unit 115 to remove the interference components. Then, the UL processing unit 116 performs demodulation processing on the received signal from which the interference components have been removed by the interference removal unit 115. The UL processing unit 116 outputs the data signal that has been subjected to the demodulation processing to the transmission unit 111.

[0030] The antenna device 20 includes an RF unit 21. The RF unit 21 performs wireless communication with the terminal device 30. The RF unit 21 transmits a transmission signal output from the base station 10 to the terminal device 30 by wireless as a DL signal. The RF unit 21 shares a replica signal of the transmission signal with the base station 10 and other antenna devices 20. The RF unit 21 receives a UL signal transmitted from the terminal device 30 by wireless. The RF unit 21 outputs the received UL signal to the base station 10 as a received signal.

[0031] Next, an overview of the present invention will be described using Figures 3 to 5. Figure 3 is a diagram showing an example of transmission and reception in a wireless communication system 100 according to an embodiment. Figure 3 shows an example in which communication is performed between antenna devices 20-1 and 20-2 and a terminal device 30. In other words, in Figure 3, it is assumed that communication is not performed by the RF unit 12 provided in the base station 10. Figure 4 is a diagram showing transmission and reception timings assigned to terminal devices 30-1 to 30-3 in the wireless communication system 100 shown in Figure 3. Figure 5 is a diagram showing an example of information buffered in the base station 10 and the antenna device 20.

[0032] In the example shown in FIG. 3, the antenna device 20-1 transmits a DL signal d ＤＬ１ The terminal device 30-3 transmits a UL signal d ＵＬ The antenna device 20-2 transmits a DL signal d ＤＬ２ Under such circumstances, the received signal r received by the antenna device 20-2 is expressed by the following equation (1).

[0033]

[0034] H in formula (1) ＵＬ represents the transfer function between the terminal device 30-3 and the antenna device 20-2, and H ＤＬ１ represents the transfer function between the antenna device 20-1 and the antenna device 20-2, and H ＤＬ２ represents the transfer function between the antenna device 20-2 and the antenna device 20-2, and AWGN represents additive white Gaussian noise. Note that, since communication is not performed by the RF unit 12 provided in the base station 10, information regarding the RF unit 12 is not included.

[0035] As shown in equation (1), the received signal r received by the antenna device 20-2 includes the DL signal transmitted by the antenna device 20-1 and the reflection of the DL signal transmitted by the antenna device 20-2. Therefore, the base station 10 calculates the replica signal d ＤＬ１ , d ＤＬ２ Transfer function H ＤＬ１ , H ＤＬ２The value obtained by multiplying r by r is subtracted from the received signal r. This makes it possible to remove CLI. Note that although a simplified example is shown in Fig. 5, the transfer function and delay time are buffered for each combination of transmitting and receiving beams in the base station 10 and each antenna device 20.

[0036] Fig. 6 is a flowchart showing a processing flow of the base station 10 in the embodiment. Fig. 6 explains a processing flow for updating information on replica signals of the base station 10 and each antenna device 20 required for removing CLI, and delay times and transfer functions of DL signals between the base station 10 and each antenna device 20 that cause CLI.

[0037] The base station 10 buffers replica signals from the base station 10 and each antenna device 20 (step S101). The base station 10 determines whether to update the information used for CLI removal (step S102). If the base station 10 determines to update the information used for CLI removal (step S102-YES), the base station 10 receives DL signals transmitted from each antenna device 20 (step S103).

[0038] The delay acquisition unit 113 acquires the delay time between the base station 10 and the antenna device 20 for each antenna device 20 based on the received DL signal. The delay acquisition unit 113 stores the acquired delay time information in a buffer for each antenna device 20 (step S104). The base station 10 uses the acquired delay time to establish synchronization between the received signal and the replica signal used to estimate the transfer function.

[0039] The transfer function estimation unit 114 estimates the transfer function of the propagation path between the base station 10 and the antenna device 20 for each antenna device 20 based on the received DL signal and the replica signals of the base station 10 and each antenna device 20. The transfer function estimation unit 114 stores information on the estimated transfer function for each antenna device 20 in a buffer (step S105).

[0040] The above-mentioned acquisition of delay times and estimation of transfer functions may be performed at a timing when there is no UL reception from the base station 10 and the antenna device 20 in order to prevent accuracy degradation due to UL reception. Furthermore, acquisition of delay times and estimation of transfer functions may be performed multiple times, or may be buffered after averaging or processing of abnormal values. The acquisition of delay times and estimation of transfer functions are performed for each combination of transmitting and receiving beams at the base station 10 and each antenna device 20.

[0041] In the flowchart shown in FIG. 6, in order to obtain a more accurate transfer function, the transfer function may be estimated at a timing when there is little interference from devices other than the target of estimation. In this configuration, if the base station 10 determines in the processing of step S102 that the information used for CLI removal should be updated (step S102-YES), the base station 10 determines whether there is little interference from devices other than the target of estimation. Devices other than the target of estimation are devices other than the device whose transfer function is to be estimated. For example, when estimating the transfer function between the base station 10 and antenna device 20-1, antenna device 20-2 is a device other than the target of estimation.

[0042] If there is little interference from devices other than the target of estimation, the base station 10 executes the process of step S103. Here, a case where there is little interference means, for example, when there is no transmission from devices other than the target of estimation, or when only transmissions with interference below a certain threshold are detected in interference measurement using conventional functions. On the other hand, if there is a lot of interference from devices other than the target of estimation, the base station 10 ends the process of FIG. 6. By performing such a process, a more accurate transfer function can be obtained, thereby further reducing the impact of CLI.

[0043] Fig. 7 is a flowchart showing the flow of processing by the base station 10 in this embodiment. Fig. 7 explains the flow of processing for removing CLI when the base station 10 demodulates an UL signal. The processing in Fig. 7 is executed when an UL signal is received from the terminal device 30. Here, as in Fig. 3, an example will be explained in which an UL signal is received by the antenna device 20-2.

[0044] The RF unit 21-2 of the antenna device 20-2 receives an UL signal transmitted from the terminal device 30-3 (step S201). The RF unit 21-2 outputs the received UL signal to the base station 10. The UL processing unit 116 of the base station 10 demodulates the UL signal output from the antenna device 20-2 (step S202). Thereafter, the UL processing unit 116 determines whether a demodulation error has occurred (step S203). If the UL processing unit 116 can correctly demodulate the data signal, it determines that no demodulation error has occurred. On the other hand, if the UL processing unit 116 cannot correctly demodulate the data signal, it determines that a demodulation error has occurred.

[0045] If the UL processing unit 116 determines that no demodulation error has occurred (step S203—NO), the processing in FIG. 7 ends. In this case, the UL processing unit 116 outputs the demodulated data signal to the transmission unit 111. The transmission unit 111 transmits the data signal output from the UL processing unit 116 to a higher-level device.

[0046] If the UL processing unit 116 determines that a demodulation error has occurred (step S203—YES), the UL processing unit 116 determines whether CLI removal processing is necessary (step S204). The CLI removal processing is processing for removing interference components from the received signal. The base station 10 may perform the CLI removal processing every time the processing of FIG. 7 is performed, may perform the CLI removal processing only when a demodulation error has occurred in the processing of step S203, or may perform the CLI removal processing only when instructed to do so.

[0047] If the UL processing unit 116 determines that CLI removal processing is not necessary (step S204—NO), the processing of FIG. 7 ends. Examples of cases where CLI removal processing is not necessary include cases where the interference measurement results show almost no CLI influence, cases where the demodulation error is so large that it is estimated that influences other than CLI are significant and therefore retransmission is preferable, or cases where replica signal and transfer function information cannot be buffered. On the other hand, if the UL processing unit 116 determines that CLI removal processing is necessary (step S204—YES), the UL processing unit 116 instructs the interference removal unit 115 to perform CLI removal processing. In response to the instruction from the UL processing unit 116, the interference removal unit 115 removes interference components from the UL signal using the buffered replica signals of the base station 10 and each antenna device 20 and information on the transfer function of the DL signal between the base station 10 or antenna device 20 that is causing the CLI (step S205).

[0048] The CLI removal process may remove CLIs above a certain threshold all at once, or may be performed in order of predicted CLIs, starting with those predicted to have the largest CLIs, and confirm that demodulation errors are eliminated each time. When removing CLIs in order of predicted CLIs, possible methods include removing CLIs in order of the received power of CLIs calculated based on the estimated CLI transfer function, or removing CLIs in order of self-interference → nearest antenna device 20 → second-nearest, etc. Furthermore, when estimating the transfer function of a DL signal in advance, if there is a large deviation between multiple estimated values, CLI removal using the estimated value may not be performed.

[0049] One possible method for establishing synchronization between the CLI component contained in the UL signal and the replica signal and transfer function is to calculate the correlation value between the buffered replica signal multiplied by the transfer function. However, if the SNR of the CLI is small and synchronization cannot be established, synchronization can be established using a delay time that has been measured and buffered in advance, and interference can be removed.

[0050] After the CLI removal process, the interference removal unit 115 outputs the UL signal from which the interference component has been removed to the UL processing unit 116. The UL processing unit 116 again demodulates the UL signal output from the interference removal unit 115 (step S206). Thereafter, the UL processing unit 116 determines whether a demodulation error has occurred, and if the UL signal demodulation error has not improved, it fine-tunes the delay time and performs interference removal again.

[0051] In cases where the SNR (Signal-to-Noise Ratio) of the UL signal is small and the SNR of the CLI from a certain base station or antenna device 20 is large, the transfer function of the CLI may be estimated even when the UL signal is received, and the estimated value may be used to remove the interference component.

[0052] According to the wireless communication system 100 configured as described above, the base station 10 includes a plurality of antenna devices 20 arranged in a dispersed manner, a transfer function estimation unit 114 that estimates the transfer function of the transmission path between the base station 10 and the plurality of antenna devices 20, and an interference removal unit 115 that removes interference components from the received UL signal based on the transfer function estimated by the transfer function estimation unit 114 and a replica signal of an interfered device (e.g., one of the plurality of antenna devices 20) that is transmitting a DL signal at the reception timing of the UL signal.

[0053] In this way, in the wireless communication system 100, replica signals of DL signals transmitted from the base station 10 and the antenna device 20, respectively, and the transfer function between the base station 10 and the antenna device 20 are shared between the devices, and interference components are removed from received UL signals. This eliminates the delay in resource allocation that occurs in the past, and eliminates the need to transmit a dedicated signal for interference measurement. Therefore, no extra resources are used. Furthermore, because replica signals of DL signals transmitted from the base station 10 and the antenna device 20 are shared between the devices, CLI can be removed from received signals by signal processing. This makes it possible to reduce interference between the uplink and downlink while improving resource utilization efficiency in the wireless communication system.

[0054] Some or all of the functional units of the base station 10 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 in 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.

[0055] Some or all of the functional units of base station 10 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).

[0056] The base station 10 in the above-described embodiment can be read as a "radio base station", a "NodeB", an "eNodeB", a "gNodeB", an "access point", a "cell", a "macrocell", a "small cell", a "femtocell", or a "picocell".

[0057] 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)".

[0058] (Variation 1) In the above-described embodiment, a configuration was shown in which DL signal information (e.g., replica signals, transfer functions, etc.) is shared between one base station 10 and multiple antenna devices 20. In contrast, the wireless communication system 100 may include multiple base stations 10, and the multiple base stations 10 may share DL signal information (e.g., replica signals, transfer functions, etc.) to remove interference components. One such situation may be when a base station 10 is communicating with a terminal device 30 and a transmission signal from another base station becomes an interference signal. In this configuration, the transfer function estimation unit 114 included in the base station 10 estimates the transfer function of the transmission path between the other base station and the base station 10 itself. The delay acquisition unit 113 included in the base station 10 acquires the delay time of the transmission path between the other base station and the base station 10 itself. The interference removal unit 115 removes interference components (e.g., transmission signals of other base stations) from the received signal based on the transfer function estimated by the transfer function estimation unit 114 and a replica signal of a transmission signal of an interfered device (e.g., another base station) that transmits a transmission signal (second signal) at the reception timing of the received signal (first signal) at the base station 10. Since the other base stations share information about the DL signal (e.g., replica signal, transfer function, etc.) with the base station 10, the other base stations can also perform similar operations.

[0059] (Variation 2) In the above-described embodiment, in the downlink or uplink, a signal may be transmitted to a single base station, a single antenna device 20, a single DA, or a single terminal device, or may be transmitted to multiple devices simultaneously.

[0060] 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.

[0061] 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.

[0062] REFERENCE SIGNS LIST 10... base station, 20, 20-1 to 20-2... antenna devices, 30... terminal device, 11... baseband unit, 12... RF unit, 111... transmission unit, 112... DL processing unit, 113... delay acquisition unit, 114... transfer function estimation unit, 115... interference removal unit, 116... UL processing unit

Claims

1. A base station comprising: a transfer function estimation unit that estimates the transfer function of a transmission path between the base station and a plurality of dispersedly arranged antenna devices or other base stations; and an interference removal unit that removes interference components from the received first signal based on the transfer function estimated by the transfer function estimation unit and a replica signal of the second signal of an interference target device that is transmitting a second signal at the reception timing of the first signal.

2. The base station according to claim 1, further comprising a delay acquisition unit that acquires a delay time of a transmission path between the plurality of antenna devices or the other base station and the base station itself, and the transfer function estimation unit uses the delay time to establish synchronization between the received signal used to estimate the transfer function and the replica signal, thereby estimating the transfer function.

3. A wireless communication system comprising a first base station and a plurality of antenna devices or a second base station that are distributed, wherein the plurality of antenna devices or the second base station transmits a second signal to a terminal device and shares a replica signal of the transmitted second signal with the first base station, and the first base station comprises: a transfer function estimation unit that estimates a transfer function of a transmission path between the plurality of antenna devices or the second base station and the first base station; and an interference removal unit that removes interference components from the received first signal based on the transfer function estimated by the transfer function estimation unit and the replica signal of the second signal shared by one of the plurality of antenna devices that is transmitting the second signal at the timing of receiving the first signal or the second base station.

4. A wireless communication method that estimates the transfer function of the transmission path between the device itself and multiple antenna devices or other base stations that are distributed in a distributed manner, and removes interference components from the received first signal based on the estimated transfer function and a replica signal of the second signal from an interfering device that is transmitting a second signal at the same time as the first signal is received.

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