Relay station, information processing device, and method

Abstract

To select a transmission antenna and a reception antenna from a plurality of antennas provided in a relay station that executes a non-regenerative relay so as to enable a provision of a stable communication.SOLUTION: A relay station comprises a plurality of antennas and a control part. The control part estimates SINR on a first signal after relay in a reception station on the basis of transmission power of the first signal in a transmission station in the case where one or more first antennas are set to a reception antenna of the first signal when the first signal is related in a non-regenerative relay and one or more second antennas are set to a transmission antenna of the first signal after relay, a first transmission characteristic between the one or more first antennas and the transmission station, a second transmission characteristic between the one or more second antennas and the reception station, noise power and interference power in the relay station, and the noise power in the reception station. The relay station also determines the first and second antennas that are a combination so that the SINR of the first signal in the reception station becomes the maximum are determined as the reception antenna and the transmission antenna, respectively.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present disclosure relates to a relay station, an information processing device, and a method. [Background technology]

[0002] Wireless communications such as the 5th Generation Mobile Communication System (5G) are expected to achieve ultra-low latency communications of sub-milliseconds or less. On the other hand, from the perspective of improving communication services, it is desirable to expand the coverage area of ​​cells, and relay communication via relay stations is an effective way to achieve this. Therefore, wireless communication methods have been proposed in which the terminal station performing wireless communication acts as the relay station. Furthermore, as a relay technology with low latency, non-regenerative relaying, in which the relay station does not perform demodulation or decoding, is desirable. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] 3GPP TS 38.174 V17.0.0 (2022-03) [Non-patent document 2] 3GPP TS 38.106 V1.0.0 (2022-03) Summary of the Invention [Problem to be solved by the invention]

[0004] One aspect of the present disclosure is to provide a relay station, an information processing device, and a method that can select an antenna to be used for transmission and an antenna to be used for reception from multiple antennas provided in the relay station that performs non-regenerative relay so as to provide stable communication. [Means for solving the problem]

[0005] One aspect of the present disclosure is A plurality of antennas; When relaying a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding it, estimating a Signal to Interference and Noise power Ratio (SINR) of the first signal after the relaying at the receiving station based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station, a second propagation characteristic between the second antenna and the receiving station, noise power and interference power at a relay station, and noise power at the receiving station, when one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after the relaying; determining the one or more first antennas and the one or more second antennas in a combination that maximizes the SINR of the first signal after the relay at the receiving station as the receiving antennas and the transmitting antennas, respectively; a control unit that executes the above; It is a relay station equipped with:

[0006] Another aspect of the present disclosure is When a relay station having a plurality of antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding it, one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after the relay, a signal strength of the first signal after the relay at the receiving station is calculated based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station and a second propagation characteristic between the second antenna and the receiving station, a noise power and an interference power at the relay station, and a noise power at the receiving station. estimating a SINR for the first signal; determining the one or more first antennas and the one or more second antennas in a combination that maximizes the SINR of the first signal after the relay at the receiving station as the receiving antennas and the transmitting antennas, respectively; a control unit that executes the above; The information processing device is provided with:

[0007] Another aspect of the present disclosure is The computer When a relay station having a plurality of antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding it, and one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after the relay, estimating an SINR of the first signal after the relay at the receiving station based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station, a second propagation characteristic between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station; determining the one or more first antennas and the one or more second antennas in a combination that maximizes the SINR of the first signal after the relay at the receiving station as the receiving antennas and the transmitting antennas, respectively; The method includes: [Effects of the Invention]

[0008] According to one aspect of the present disclosure, it is possible to select an antenna to be used for transmission and an antenna to be used for reception from among multiple antennas provided at a relay station that performs non-regenerative relay so as to provide stable communication. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating an example of a system configuration of a communication system according to the first embodiment. [Figure 2] FIG. 2 is a diagram illustrating an example of a system configuration of a communication system. [Figure 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of a relay station. [Figure 4] FIG. 4 is a diagram showing the power of a signal in each device when non-regenerative relaying is performed in a relay station and the values ​​of parameters used to calculate the SINR. [Figure 5] FIG. 5 is a diagram showing a method for creating a measurement combination when a relay station has six antennas. [Figure 6] FIG. 6 is a diagram showing a method for creating a measurement combination when a relay station has eight antennas. [Figure 7] FIG. 7 is an example of a flowchart of a process for determining the receiving antennas and transmitting antennas to be used for non-regenerative relaying at a relay station. [Figure 8] FIG. 8 is an example of a flowchart of a process for measuring propagation characteristics between antennas of relay stations. [Figure 9] FIG. 9 is an example of a flowchart of a process for determining the transmitting antenna and receiving antenna to be used for non-regenerative relaying at a relay station. [Figure 10] FIG. 10 is a diagram illustrating an example of a hardware configuration of the control device. [Figure 11] FIG. 11 is an example of a flowchart of a process performed by the control device according to the second embodiment to determine the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station. [Figure 12] FIG. 12 is a diagram showing an example of a processing sequence according to the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] When a relay station has multiple antennas, the propagation characteristics between the transmitting station and the receiving station differ for each antenna. Therefore, when the relay station performs non-regenerative relay, the antennas used as the transmitting antenna and the receiving antenna affect communication quality. In view of this, one aspect of the present disclosure aims to select a transmitting antenna and a receiving antenna from multiple antennas at a relay station performing non-regenerative relay so as to provide stable communication quality.

[0011] One aspect of the present disclosure is a relay station including multiple antennas and a controller. When performing non-regenerative relaying, in which a first signal transmitted from a transmitting station to a receiving station is relayed without demodulating or decoding, the controller of the relay station estimates a SINR of the first signal after relay at the receiving station, where one or more first antennas among the multiple antennas are used as receiving antennas for the first signal and one or more second antennas among the multiple antennas are used as transmitting antennas for the relayed first signal. The SINR is estimated based on the transmission power of the first signal at the transmitting station, first propagation characteristics between the one or more first antennas and the transmitting station, second propagation characteristics between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station. The controller determines the combination of one or more first antennas and one or more second antennas that maximizes the SINR of the first signal after relay at the receiving station as receiving antennas for receiving the first signal and transmitting antennas for transmitting the relayed first signal, respectively.

[0012] The relay station may be, for example, a base station, a small base station, a mobile base station, a smartphone, or an in-vehicle device. The relay station performs non-regenerative relay, relaying a signal without demodulating or decoding it. The control unit may be, for example, a computer, a processor such as a CPU (Central Processing Unit), an FP (Programmable Receiver), or the like. It is an arithmetic circuit such as a GA (Field Programmable Gate Array). For example, the transmitting station is a base station The receiving station is a terminal station, but is not limited to this, and the transmitting station may be a terminal station and the receiving station may be a base station.

[0013] The SINR of the first signal after relay at the receiving station is obtained based on the received power of the first signal after relay at the receiving station, the interference power of the interfering signal from the relay station, and noise power. The received power of the first signal after relay at the receiving station can be obtained based on the transmission power of the first signal from the transmitting antenna of the relay station and second propagation characteristics between the transmitting antenna of the relay station and the receiving station. The transmission power of the first signal from the transmitting antenna of the relay station can be obtained based on at least the transmission power of the first signal at the transmitting station and first propagation characteristics between the transmitting station and the receiving antenna of the relay station. Therefore, the received power of the first signal after relay at the receiving station can be obtained based on the transmission power of the first signal at the transmitting station, the first propagation characteristics between the transmitting station and the receiving antenna of the relay station, and the second propagation characteristics between the transmitting antenna of the relay station and the receiving station. The received power of the interference signal from the relay station at the receiving station can be obtained based on the noise power and interference power at the relay station and the second propagation characteristic between the transmitting antenna of the relay station and the receiving station. The noise power at the receiving station may be obtained by, for example, being notified from the receiving station through a control channel prior to transmission of the first signal, or the noise power at the relay station may be used as an approximate value.

[0014] The transmission power of the first signal at the transmitting station is notified, for example, from the transmitting station via a control channel prior to transmission of the first signal. The first propagation characteristics between each antenna of the relay station and the transmitting station may be measured by the relay station based on a reference signal from the transmitting station, or may be obtained by the transmitting station measuring and notifying the relay station. The second propagation characteristics between each antenna of the relay station and the receiving station may be measured by the relay station based on a reference signal from the receiving station, or may be obtained by the receiving station measuring and notifying the relay station. The noise power at the relay station is a predetermined value. The interference power at the relay station may be measured by the relay station, or may be set as a predetermined value. Note that the propagation characteristics are In one aspect of the disclosure, the channel matrix, channel coefficients, or coefficients indicating the attenuation of signal power due to propagation, called path loss coefficients, are used.

[0015] In one aspect of the present disclosure, the relay station can determine the receiving antenna and the transmitting antenna that maximize the SINR by estimating the SINR of the first signal after relaying, even if the SINR is not fed back from the receiving station. This makes it possible to provide stable wireless communication between the transmitting station and the receiving station when the relay station performs non-regenerative relay. Note that the number of receiving antennas and transmitting antennas selected from the multiple antennas of the relay station is not limited to one, and multiple antennas may be selected.

[0016] In one aspect of the present disclosure, the relay station may acquire interference power at the relay station by measuring it itself. When the relay station performs non-regenerative relaying, self-interference occurs between the transmitting antenna and the receiving antenna. To suppress this self-interference, the relay station further includes a first filter. In this case, the control unit may create multiple combinations of one or more first antennas as receiving antennas and one or more second antennas as transmitting antennas from among the multiple antennas. For each of the multiple combinations, the control unit may calculate the SINR of the first signal after relay at the receiving station based on the transmission power of the first signal at the transmitting station, first propagation characteristics between the transmitting station and the one or more first antennas, second propagation characteristics between the one or more second antennas and the receiving station, the allowable transmission power value of the first signal at the relay station, the amount of interference power suppression by the first filter, third propagation characteristics between the one or more first antennas and the one or more second antennas, noise power at the relay station, and noise power at the receiving station. The control unit may determine one or more first antennas as receiving antennas for receiving the first signal and one or more second antennas as transmitting antennas for transmitting the first signal after relaying, in a combination that maximizes the SINR at the receiving station.

[0017] The interference power at the relay station can be obtained based on the allowable transmission power value at the relay station, a third propagation characteristic between the receiving antenna (first antenna) and the transmitting antenna (second antenna), and the amount of interference power suppression by the first filter. The third propagation characteristic between the receiving antenna (first antenna) and the transmitting antenna (second antenna) may be measured, for example, by the relay station transmitting a reference signal from the transmitting antenna (second antenna) and receiving it at the receiving antenna (first antenna). By having the relay station measure and obtain the interference power at the relay station itself, a value that is more suited to the propagation environment can be obtained, and the SINR at the receiving station can be estimated more accurately.

[0018] In one aspect of the present disclosure, the relay station may amplify a first signal in a non-regenerative relaying scheme. In this case, the transmission power of the first signal transmitted from the transmitting antenna of the relay station can be expressed using the received power of the first signal at the receiving antenna of the relay station and the amplification gain at the relay station. In addition, together with the amplification of the first signal, interference power and noise power at the relay station are also amplified. Therefore, the received power of the interference signal from the relay station at the receiving station can be expressed using the noise power and interference power at the relay station, a second propagation characteristic between the transmitting antenna of the relay station and the receiving station, and the amplification gain at the relay station.

[0019] For this reason, in one aspect of the present disclosure, the control unit calculates an amplification gain at the relay station and uses the amplification gain to calculate the SINR of the first signal after relay at the receiving station. The amplification gain at the relay station can be obtained based on the transmission power and reception power of the first signal at the relay station. The transmission power of the first signal at the relay station can be obtained based on the allowable transmission power value of the first signal at the relay station and the interference power and noise power at the relay station. The allowable transmission power value of the first signal at the relay station may be set in advance, or may be notified from the transmitting station via a control channel prior to transmission of the first signal. The reception power of the first signal at the relay station is obtained by calculating the transmission power of the first signal at the transmitting station and the reception amplifier of the relay station. The first propagation characteristic between the receiver and the transmitting station can be obtained based on the first propagation characteristic.

[0020] That is, the amplification gain at the relay station is calculated based on the transmission power of the first signal at the transmitting station, the allowable transmission power value of the first signal at the relay station, the amount of interference power suppression by the first filter, the noise power added at the relay station, the first propagation characteristic between one or more first antennas (receiving antennas) and the transmitting station, and the third propagation characteristic between one or more first antennas (receiving antennas) and one or more second antennas (transmitting antennas).

[0021] When the amplification gain of the relay station is used, the received signal power of the first signal after relay at the receiving station is obtained using the transmission power of the first signal at the transmitting station, first propagation characteristics between one or more first antennas (receiving antennas) and the transmitting station, the amplification gain, and second propagation characteristics between one or more second antennas (transmitting antennas) and the receiving station. The received signal power of the interference signal transmitted from the relay station at the receiving station is obtained based on the allowable transmission power value of the first signal at the relay station, third propagation characteristics between one or more first antennas (receiving antennas) and one or more second antennas (transmitting antennas), the amount of interference power suppression by the first filter, noise power added at the relay station, the amplification gain, and second propagation characteristics between one or more second antennas (transmitting antennas) and the receiving station.

[0022] According to one aspect of the present disclosure, even when the first signal is amplified in the relay station, the SINR of the first signal after relay in the receiving station can be obtained more accurately.

[0023] In one aspect of the present disclosure, when the transmitting station is a base station and the receiving station is a terminal station, the control unit may use the noise power value at the relay station as an approximation of the noise power at the receiving station. For example, the 5G standard stipulates that the relay station has the same reception performance as the terminal station, so the noise power value at the relay station can be used as an approximation of the noise power at the terminal station. This eliminates the need for communication to inquire of the terminal station about the noise power at the terminal station as the receiving station, thereby efficiently determining the receiving antenna and transmitting antenna to be used for non-regenerative relay.

[0024] In one aspect of the present disclosure, the control unit may measure a first propagation characteristic between each of the plurality of antennas and the transmitting station based on a reference signal from the transmitting station. The control unit may also measure a second propagation characteristic between each of the plurality of antennas and the receiving station based on a reference signal from the receiving station. The control unit may also measure a third propagation characteristic between each of the plurality of antennas by transmitting a reference signal from at least some of the plurality of antennas. By having the relay station acquire these values ​​through measurements, communication for inquiring about these values ​​to the receiving station and the transmitting station can be omitted, thereby enabling efficient determination of the receiving antennas and transmitting antennas to be used for non-regenerative relay.

[0025] In one aspect of the present disclosure, the control unit may create K first combinations of multiple antennas, each including one or more transmitting antennas that simultaneously transmit reference signals and one or more receiving antennas that simultaneously receive the reference signals transmitted from the one or more transmitting antennas. The control unit may measure third propagation characteristics between each of the multiple antennas through transmission and reception of the reference signals for each of the K first combinations. K is an integer obtained by rounding up the decimal point of the logarithm to base 2, where N is the number of multiple antennas. The K first combinations include a second combination obtained by selecting two antennas, a third antenna and a fourth antenna, from the multiple antennas among the K first combinations, the second combination being a combination of the third antenna as a transmitting antenna for the reference signal and the fourth antenna as a receiving antenna for the reference signal, and a combination of the fourth antenna as a transmitting antenna for the reference signal and the third antenna as a receiving antenna for the reference signal. It is created so that there is no overlap in any of the combinations.

[0026] This minimizes the number of times that a reference signal is transmitted from a transmitting antenna and received by a receiving antenna, thereby shortening the time required to measure the third propagation characteristic between each of the multiple antennas and efficiently determining the receiving antennas and transmitting antennas to be used for non-regenerative relay.

[0027] Another aspect of the present disclosure is an information processing device, separate from a relay station, that determines the receiving antennas and transmitting antennas to be used for non-regenerative relaying at the relay station. The information processing device may be, for example, a base station, a control device connected to the base station, or a terminal station. The information processing device includes a control unit that, when a relay station equipped with multiple antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding it, and one or more first antennas among the multiple antennas are used as receiving antennas for the first signal and one or more second antennas among the multiple antennas are used as transmitting antennas for the first signal after relaying, estimates the SINR of the first signal after relaying at the receiving station based on the transmission power of the first signal at the transmitting station, first propagation characteristics between the one or more first antennas and the transmitting station and second propagation characteristics between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station, and determines one or more first antennas and one or more second antennas in a combination that maximizes the SINR as receiving antennas for receiving the first signal and transmitting antennas for transmitting the first signal after relaying, respectively.

[0028] The information processing device may acquire, for each of the plurality of antennas, a first propagation characteristic between the transmitting station and the receiving station, a second propagation characteristic between the transmitting station and the receiving station, and noise power at the relay station, for example, by notification from the relay station. The information processing device may, for example, calculate interference power at the relay station based on notification from the relay station or information obtained from the relay station. The information processing device may, for example, acquire noise power at the receiving station from a preset value stored in advance, by notification from the receiving station, or by approximating the noise power at the relay station.

[0029] When the information processing device calculates the interference power at the relay station, the calculation is based on the allowable transmission power value of the first signal at the relay station, the amount of interference power suppression by the first filter at the relay station, and third propagation characteristics between one or more first antennas and one or more second antennas. The allowable transmission power value of the first signal at the relay station, the amount of interference power suppression by the first filter at the relay station, and the third propagation characteristics between each of the multiple antennas may be acquired by being notified from the relay station, for example.

[0030] Furthermore, the information processing device may create K first combinations of multiple antennas, each combination including one or more transmitting antennas that simultaneously transmit reference signals and one or more receiving antennas that receive the reference signals simultaneously transmitted from the one or more transmitting antennas. The information processing device may instruct the relay station to measure third propagation characteristics between each of the multiple antennas for each of the K first combinations through transmission and reception of reference signals. The information processing device may receive notification from the relay station of the measurement results of the third propagation characteristics between each of the multiple antennas and use these to calculate interference power at the relay station. The K first combinations are the same as the K first combinations created by the relay station described above.

[0031] Another aspect of the present disclosure can be specified as a method for a computer to execute the process executed by the relay station or the information processing device. Specifically, the method includes a step of a computer receiving a first signal from one or more first antennas of a plurality of antennas when the relay station having a plurality of antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating and decoding the first signal. and determining, based on the transmission power of the first signal at the transmitting station, first propagation characteristics between the one or more first antennas and the transmitting station and second propagation characteristics between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station, where the relay station is used as a receiving antenna for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the relayed first signal.

[0032] Another aspect can be specified as a program for causing a relay station or a control device to execute the method, and a computer-readable non-transitory storage medium on which the program is recorded.

[0033] Hereinafter, embodiments of the present disclosure will be described with reference to the accompanying drawings. The configurations of the following embodiments are examples, and the present disclosure is not limited to the configurations of the embodiments.

[0034] First Embodiment FIG. 1 is a diagram showing an example of the system configuration of a communication system 100A according to the first embodiment. The communication system 100A includes a control device 1, a base station 2, relay stations 3 (3-1, ..., 3-M), and a terminal station 4. The control device 1 is a device on a core network to which the base station 2 is connected. However, the control device 1 can also be considered to be the core network itself, or a system included in the core network. The core network includes, for example, an optical fiber network. The control device 1 controls the base station 2, relay stations 3, and terminal station 4, and provides communication services to the terminal station 4.

[0035] The base station 2 provides a wireless access network to the terminal station 4. An area where wireless communication is possible in the wireless access network is also called a cell. In the first embodiment, the base station 2 has one or more antennas (for example, #1), a radio 21 connected to the one or more antennas, and a control circuit 22. The control circuit 22 has, for example, a processor and a memory. The processor controls communication with the control device 1 and wireless communication with the relay station 3 and the terminal station 4 using a computer program on the memory.

[0036] The terminal station 4 is, for example, a mobile station such as a smartphone, a tablet terminal, a wearable terminal, or an in-vehicle data communication device. However, the present invention is not limited to this, and the terminal station 4 may be a stationary terminal device. For example, the terminal device connects to a wireless access network within the range of a cell provided by the base station 2. The relay station 3 relays wireless communication between the base station 2 and the terminal station 4. The relay station 3 is, for example, a small base station, a mobile base station, an in-vehicle device, or a smartphone. In the first embodiment, the relay station 3 is a device selected as a relay station by the control device 1 from devices having a configuration capable of non-regenerative relaying.

[0037] When a connection request is generated from a terminal station 4, the control device 1 selects one or more devices located within the range of the cell provided by the base station 2 as relay stations 3 and instructs them to relay wireless communication. In the first embodiment, when multiple relay stations 3 are to be individually distinguished, they are assigned sub-numbers such as relay station 3-1, ..., 3-M. Here, the sub-number M is an integer indicating the number of relay stations 3. In FIG. 1, relay stations 3-1 and 3-M are illustrated as examples. However, when relay stations 3-1, ..., 3-M are collectively referred to, they are simply referred to as relay station 3.

[0038] The relay station 3 has a plurality of antennas (for example, #1, ..., #N), a plurality of radio devices 31 connected to the plurality of antennas, respectively, and a control unit 32. Note that in Fig. 1, the plurality of radio devices 31 are shown as one radio device 31 for convenience.

[0039] The terminal station 4 has one or more antennas (for example, #1), a radio 41 connected to the one or more antennas, and a control circuit 42. For example, a mobile station within a cell requests the base station 2 to connect to the radio access network, and when connected, the mobile station operates as the terminal station 4. The mobile station within the cell may request the base station 2 directly to connect to the radio access network. Alternatively, the mobile station within the cell may request the base station 2 to connect to the radio access network via a device operating as a relay station 3 within the cell. The terminal station 4 can be said to be a station that can communicate with the base station 2 via one or more relay stations 3 or without via any of the one or more relay stations 3.

[0040] FIG. 2 is a diagram illustrating an example of the system configuration of a communication system 100B. In the first embodiment, the system configuration may be the communication system 100B. Compared to the communication system 100A in FIG. 1, the communication system 100B has a central base station 2A and one or more distributed base stations 2B instead of the base station 2. When one or more distributed base stations 2B are to be individually distinguished, a subnumber is assigned, such as distributed base stations 2B-1, ..., 2B-S. Here, the subnumber S is an integer indicating the number of distributed base stations. In FIG. 2, distributed base stations 2B-1 and 2B-S are illustrated as examples. However, when the distributed base stations 2B-1, ..., 2B-S are collectively referred to, they are simply referred to as distributed base station 2B.

[0041] The central base station 2A has a control circuit 22A. Furthermore, the distributed base station 2B has a radio 21B. The control circuit 22A of the central base station 2A and the radio 21B of the distributed base station 2B are connected by, for example, an optical fiber C1 or a wireless network. The topology of the optical fiber C1 connecting the central base station 2A and multiple distributed base stations 2B is not limited to a specific topology. For example, the topology of the optical fiber C1 may be a one-to-one connection between nodes, a network that branches with increasing distance from the central base station 2A, a star network, a ring network, or the like. Furthermore, when connecting the control circuit 22A of the central base station 2A and the radio 21B of the distributed base station 2B by a wireless network, the standard and protocol of the wireless network employed are not limited to specific ones.

[0042] 1, the control circuit 22A has a processor and a memory. The processor controls communication with the control device 1 and wireless communication with the relay station 3 and terminal station 4 using a computer program stored in the memory. That is, the control circuit 22A controls wireless communication with the relay station 3 and terminal station 4 via the radio 21B of one or more distributed base stations 2B.

[0043] In the communication systems 100A and 100B, the control unit 32 of the relay station may include an antenna for the control channel in addition to the antennas #1 to #N. Hereinafter, when there is no need to distinguish between the communication systems 100A and 100B, they will simply be referred to as the communication systems 100.

[0044] The first embodiment is based on the assumption that the following is adopted in the communication system 100. In the communication system 100, the same frequency channel is used for uplink and downlink in time division multiplexing. Furthermore, slot timing of radio frames is synchronized between the base station 2, relay station 3, and terminal station 4. In the communication system 100, a block transmission method with a cyclic prefix, such as CP-OFDM (Cyclic Prefix - Orthogonal Frequency Division Multiplexing), is adopted as the radio modulation method. Furthermore, the relay station 3 shares resource block information used by the terminal station 4 to be relayed in the uplink and downlink. Note that the uplink is a link from the terminal station 4 to the base station 2. The downlink is a link from the base station 2 to the terminal station 4. In the first embodiment, a case where non-regenerative relaying is performed in the downlink direction will be described as an example. That is, in the first embodiment, the transmitting station is the base station 2, and the receiving station is the terminal station 4. Hereinafter, the downlink direction may be referred to as the downward direction, and the uplink direction may be referred to as the upward direction.

[0045] In the first embodiment, the relay station 3 determines the receiving antenna and transmitting antenna to be used for non-regenerative relaying so as to maximize the SINR of the received signal at the terminal station 4. The relay station 3 creates combinations of a first antenna, of the multiple antennas, to be used as a receiving antenna in non-regenerative relaying and a second antenna to be used as a transmitting antenna in non-regenerative relaying, and estimates the SINR of the received signal at the terminal station 4 for all combinations. The SINR at the terminal station 4 is estimated using parameters that the relay station 3 can measure. This allows the relay station 3 to determine the receiving antenna and transmitting antenna to be used for non-regenerative relaying so as to maximize the SINR of the received signal at the terminal station 4, without feedback of the SINR from the terminal station 4.

[0046] 3 is a diagram showing an example of the hardware configuration of the relay station 3. The relay station 3 includes radio devices 31-1, ..., 31-N, a control unit 32, and a baseband circuit 33. The radio devices 31-1, ..., 31-N are connected to antennas #1, ..., #N, respectively. That is, the number of radio devices 31 is the same as the number of antennas. When the radio devices 31-1, ..., 31-N are collectively referred to, they are simply referred to as radio device 31. The radio device 31 includes a transmitter 311 and a receiver 312.

[0047] The radio device 31 and the antenna are connected via a switch. When the antenna is used as a transmitting antenna, the switch is connected to the transmitter 311, thereby connecting the antenna to the transmitter 311. When the antenna is used as a receiving antenna, the switch is connected to the receiver 312, thereby connecting the antenna to the receiver 312. In each radio device 31, the connection of the switch is switched according to an instruction from the control unit 32.

[0048] Here, the power difference between the transmitted signal and the received signal is, for example, about 100 dB. Part of the transmitted signal interferes with the received signal. This interference between part of the transmitted signal and the received signal in the radio device 31 is called self-interference. Self-interference occurs when the radio frequency (RF) This is suppressed by using both the analog filter and the FIR filter in the baseband circuit 33.

[0049] When the receiver 312 is connected to an antenna via a switch, it receives a received signal from the antenna. The receiver 312 has a quadrature detection circuit and an analog-to-digital (AD) converter. The receiver 312 down-converts the received signal using the quadrature detection circuit, and then converts it into digital data using the AD converter to obtain a baseband signal. The receiver 312 outputs the obtained baseband signal to the baseband circuit 33.

[0050] The baseband circuit 33 has an FIR filter. The baseband circuit 33 uses the FIR filter to suppress a transmission signal that has mixed into the received signal and is causing self-interference, and also delays the received signal by a predetermined delay time. The baseband circuit 33 outputs the received signal filtered by the FIR filter to the transmitter 311 of the radio device 31 corresponding to the transmitting antenna.

[0051] The transmitter 311 has a digital-to-analog (DA) converter, a modulation circuit, and an amplifier circuit. When the transmitter 311 is connected to an antenna by a switch, it receives a received signal from the baseband circuit 33. The transmitter 311 converts the received signal from the baseband circuit 33 into an analog signal, and generates an RF signal by the modulation circuit. The transmitter 311 also amplifies the power (amplitude) of the RF signal by the amplifier circuit. The transmitter 311 has a digital-to-analog (DA) converter, a modulation circuit, and an amplifier circuit. When the transmitter 311 is connected to an antenna by a switch, it receives an input of a received signal from the baseband circuit 33. The transmitter 311 converts the received signal from the baseband circuit 33 into an analog signal, and generates an RF signal by the modulation circuit. The transmitter 311 also amplifies the power (amplitude) of the RF signal by the amplifier circuit. The RF signal is transmitted as a relay signal from an antenna connected by a switch.

[0052] The control unit 32 is, for example, a processor such as a CPU or an arithmetic circuit such as an FPGA. The control unit 32 controls the non-regenerative relay process. More specifically, the control unit 32 measures the radio wave propagation characteristics of the propagation path, notifies the control device 1 of the measurement results, sets an FIR filter, and determines the receiving antenna and transmitting antenna to be used for non-regenerative relay. The control unit 32 is an example of the "control unit" of the "relay station."

[0053] The hardware configuration of relay station 3 is not limited to that shown in Fig. 3. For example, in Fig. 3, relay station 3 includes an antenna for a control channel connected to control unit 32, separate from antennas #1 to #N, but this is not limiting. For example, relay station 3 may not include an antenna for a control channel in control unit 32, and may use any of antennas #1 to #N as the antenna for the control channel.

[0054] <SINR estimation at terminal station 4> First, a case will be described in which one receiving antenna and one transmitting antenna are selected for non-regenerative relay in the relay station 3.

[0055] Fig. 4 is a diagram showing the signal power of each device and the parameter values ​​used to calculate the SINR when non-regenerative relaying is performed at relay station 3. The units of each value shown in Fig. 4 are dB (decibels). Fig. 4 also assumes that relay station 3 uses one receiving antenna and one transmitting antenna for non-regenerative relaying. Hereinafter, when simply referring to a received signal, a transmitted signal, received signal power, and transmitted signal power, they refer to the data signal transmitted from base station 2.

[0056] A signal transmitted from base station 2 to terminal station 4 is attenuated on the propagation path from base station 2 to relay station 3 before arriving at relay station 3. If the propagation characteristics from base station 2 to relay station 3 are H_(BS→R(n_(RX))), the propagation loss L_(BS→R(n_(RX))) on the propagation path from base station 2 to relay station 3 is given by the following equation 1. Note that the characters in parentheses after the underline are indicated as subscripts in the figures and equations. n_(RX) indicates the identification number of the antenna used as a receiving antenna for non-regenerative relay at relay station 3.

number

[0057] The received signal power at relay station 3 is expressed by the following equation 2, which is obtained by subtracting the propagation loss L_(BS→R(n_(RX))) of the propagation path from base station 2 to relay station 3 from the transmitted signal power P_(BS) at base station 2.

number

[0058] In the relay station 3, self-interference occurs due to a portion of the transmitted signal in the non-regenerative relay. The interference power I_(SI(n_(TX),n_(RX))) in the relay station 3 is expressed by the following equation 3. H_(R(n_(TX))→R(n_(RX))) is the propagation characteristic between the transmitting antenna n_(TX) and the receiving antenna n_(RX). P_(IS) is the amount of self-interference power suppression by the baseband circuit 33.

number

[0059] At relay station 3, the received signal is amplified by an amplification gain G_(R) during relaying. The amplification gain G_(R) at relay station 3 is given by the following equation 4. P_(R) is the allowable value of the transmission signal power at relay station 3. W_(R) is the noise power at relay station 3.

number

[0060] The received signal power R_(BS→R(n_(RX),n_(TX))→UE) when the relay signal transmitted from the relay station 3 is received at the terminal station 4 using the amplification gain G_(R) is given by the following equation 5. L_(UE→R(n_(TX))) indicates the propagation loss between the transmitting antenna of the relay station 3 and the terminal station 4. H_(UE→R(n_(TX))) indicates the propagation characteristics between the transmitting antenna of the relay station 3 and the terminal station 4.

number

[0061] The interference power I_(SI(n_(TX),n_(RX))) and noise power W_(R) at the relay station 3 are amplified by the amplification gain G_(R) together with the relayed signal and arrive at the terminal station 4 as an interference signal. The interference power I_(R(n_(RX),n_(TX)) → UE) when the interference signal transmitted from the relay station 3 is received at the terminal station 4 using the amplification gain G_(R) is given by the following equation 6. Note that the base 10 logarithm variable in one term of equation 6 is the sum of the interference power I_(SI(n_(TX),n_(RX))) and noise power W_(R) at the relay station 3 converted from decibels to watts.

number

[0062] The SINR is obtained by dividing the received signal power (W) by the sum of the interference signal power (W) and noise power (W), and converting the result into decibels. Therefore, the SINR Γ_(BS→R(n_(RX),n_(TX))) at the terminal station 4 is expressed by the following equation 7. W_(UE) is the noise power (W) at the terminal station 4.

number

[0063] In the first embodiment, the relay station 3 estimates the SINR at the terminal station 4 using Equation 7. When performing non-regenerative relaying, the control unit 32 of the relay station 3 creates combinations of one receiving antenna and one transmitting antenna from multiple antennas. The control unit 32 calculates the SINR at the terminal station 4 for all combinations according to Equations 1 to 7. The control unit 32 determines that the antenna included in the combination that maximizes the SINR at the terminal station 4 will be used for non-regenerative relaying.

[0064] Next, a method for the relay station 3 to acquire each parameter in Equations 1 to 7 will be described. The relay station 3 acquires the transmission signal power P_(BS) at the base station 2 by notification from the base station 2 via a control channel prior to transmission of a data signal from the base station 2 to the terminal station 4. The allowable value P_(R) of the transmission signal power at the relay station 3, the amount of self-interference power suppression P_(IS), and the noise power W_(R) are values ​​that are set or measured in advance. These values ​​are values ​​related to the relay station 3 itself, and therefore the relay station 3 stores them in advance in, for example, a memory in the control unit 32.

[0065] The relay station 3 acquires the propagation characteristics H_(BS→R(n_(RX))) between the base station 2 and the receiving antenna n_(RX), the propagation characteristics H_(R(n_(TX))→UE) between the transmitting antenna n_(TX) and the terminal station 4, and the propagation characteristics H_(R(n_(TX))→UE) between the transmitting antenna n_(TX) and the receiving antenna n_(RX) by measuring them. The relay station 3 cannot measure the noise power W_(UE) at the terminal station 4. Therefore, the relay station 3 uses the noise power W_(R) at the relay station 3 as an approximation of the noise power W_(UE) at the terminal station 4. Note that the 5G standard specifies that a relay station must have the same reception performance as a terminal station, so the noise power W_(UE) at the terminal station 4 can be approximated by the noise power W_(R) at the relay station 3.

[0066] Equations 1 to 7 are equations when one receiving antenna and one transmitting antenna are used for non-regenerative relay. However, multiple receiving antennas and multiple transmitting antennas may be used for non-regenerative relay. When multiple receiving antennas and multiple transmitting antennas are used for non-regenerative relay, the above equations 2 to 7 are generalized as the following equations 2G to 7G. In equations 2G to 7G, receiving antenna n_(RX) and transmitting antenna n_(TX) are vectors whose elements are candidate antenna identification numbers. Each propagation characteristic H is a channel matrix H. N_(RX) is the number of receiving antennas used for non-regenerative relay. N_(TX) is the number of transmitting antennas used for non-regenerative relay.

number

[0067] (Improving the efficiency of measuring propagation characteristics between antennas) In the first embodiment, when measuring the propagation characteristics between each of the multiple antennas of the relay station 3, orthogonal reference signals are simultaneously transmitted from multiple transmitting antennas in a MIMO (Multiple-Input and Multiple-Output) manner, and the reference signals are received by multiple receiving antennas, thereby improving the efficiency of the processing. A combination of transmitting antennas and receiving antennas for reference signals when measuring the propagation characteristics between antennas is hereinafter referred to as a measurement combination. The measurement combination is an example of a "first combination."

[0068] Figure 5 is a diagram showing how to create measurement combinations when relay station 3 has six antennas. Figure 5 shows a 6x6 grid, with antennas assigned vertically as reference signal transmitting antennas and antennas assigned horizontally as reference signal receiving antennas. For example, the propagation characteristics between transmitting antenna #x and receiving antenna #y and the propagation characteristics between transmitting antenna #y and receiving antenna #x are treated as the same because they are symmetrical, so combinations that fall within the gray triangular grid in the lower half of Figure 5 are excluded.

[0069] For example, in the blank space in the upper half of the triangular area of ​​the 6x6 grid shown in Figure 5, cells are combined to create larger squares, and this process is repeated in order. Then, cells are grouped into groups of the same shape. In the 6x6 grid shown in Figure 5, three groups can be created. In descending order of the area of ​​the cells, they are: Group #1 (transmitting antennas: #1, #2, #3, receiving antennas: #4, #5, #6), Group #2 (transmitting antennas: #1, #4, receiving antennas: #2, #3, #5, #6), and Group #3 (transmitting antennas: #2, #5, receiving antennas: #3, #6). This group is used as the combination for measurement. A reference signal is transmitted and received for each measurement combination. Therefore, if there are six antennas, the process of transmitting and receiving the reference signal to measure the propagation characteristics between the antennas only needs to be performed three times in total, the same as the number of measurement combinations.

[0070] 6 is a diagram showing a method for creating measurement combinations when relay station 3 has eight antennas. As in FIG. 5, by repeatedly creating rectangles of increasing area in the blank spaces and grouping them with rectangles of the same shape, three groups can be created as shown in FIG. 6. The groups, in descending order of area, are: Group #1 (transmitting antennas: #1, #2, #3, #4; receiving antennas: #5, #6, #7, #8), Group #2 (transmitting antennas: #1, #2, #5, #6; receiving antennas: #3, #4, #7, #8), and Group #3 (transmitting antennas: #1, #3, #5, #7; receiving antennas: #2, #4, #6, #8). Therefore, when there are eight antennas, the process of transmitting and receiving reference signals for measuring the propagation characteristics between antennas only needs to be performed three times, the same as the number of measurement combinations.

[0071] 5 and 6, the number of times the process of transmitting and receiving a reference signal for measuring the propagation characteristics between antennas is executed and the number of measurement combinations K, where the number of antennas is N, is expressed by the following equation 8. That is, K is the value obtained by rounding up the decimal point of the logarithm to the base 2 of the number of antennas N.

number

[0072] The control unit 32 creates K measurement combinations, for example, as described in FIGS. 5 and 6. For each of the K measurement combinations, the control unit 32 transmits a reference signal from the antenna assigned as the transmitting antenna and receives the reference signal at the antenna assigned as the receiving antenna. The control unit 32 measures the propagation characteristics for each antenna assigned as the receiving antenna based on the reference signal received from each antenna assigned as the transmitting antenna. This allows the control unit 32 to measure the propagation characteristics between two antennas for all combinations of two antennas selected from multiple antennas. The transmission power of the reference signal is a default value.

[0073] 5 and 6, K measurement combinations are created by sequentially creating squares made up of cells that maximize the area in the blank triangular portion of the upper half of the N×N antenna grid. However, the method for creating the K measurement combinations is not limited to this. For example, K measurement combinations may be created by sequentially creating squares made up of cells that maximize the area in the blank triangular portion of the upper half of the N×N antenna grid. For example, K measurement combinations may be created by sequentially creating squares made up of cells that maximize the size in the transmitting antenna direction (vertical direction) or the receiving antenna direction (horizontal direction) in the blank triangular portion of the upper half of the N×N antenna grid.

[0074] In other words, the K measurement combinations should be created so that the combination of two antennas, antenna #A and antenna #B, among the multiple antennas does not overlap as either a transmitting antenna and a receiving antenna, or a receiving antenna and a transmitting antenna, among the K measurement combinations.

[0075] <Processing flow> Fig. 7 is an example of a flowchart of the process of determining the receiving antennas and transmitting antennas to be used for non-regenerative relay by the relay station 3. The process shown in Fig. 7 is repeatedly executed for each radio frame, for example, from the time when a relay start instruction is received from the base station 2 via the control channel until a relay end instruction is received. The relay start instruction from the base station 2 is transmitted, for example, when the base station 2 receives a connection request from the terminal station 4. The relay end instruction from the base station 2 is transmitted, for example, when the communication of the terminal station 4 is terminated.

[0076] In OP101, the control unit 32 measures the propagation characteristic H_(UE→R(n)) between the terminal station 4 and all antennas. n indicates the identification number of the antenna and takes a value from 1 to N, for example. The propagation characteristic H_(UE→R(n)) between the terminal station 4 and all antennas is measured based on the reference signal received, for example, via a control channel, transmitted from the terminal station 4. The transmission power of the reference signal transmitted from the terminal station 4 is known.

[0077] In OP102, the control unit 32 measures the propagation characteristics H_(BS→R(n)) between the base station 2 for all antennas. The propagation characteristics H_(BS→R(n)) between the base station 2 are measured based on the reference signals received by all antennas, for example, via a control channel, from the base station 2. The transmission power of the reference signals transmitted from the base station 2 is known.

[0078] In OP103, the control unit 32 measures the propagation characteristics H_(R(n_(k))→R(n_(l))) between the antennas. n_(k) and n_(l) respectively indicate the identification numbers of the antennas, and n_(k)≠n_(l). The process of measuring the propagation characteristics between the antennas in OP103 will be described in detail later.

[0079] In OP104, the control unit 32 determines the transmitting antenna and the receiving antenna to be used for non-regenerative repeating. The process of determining the transmitting antenna and the receiving antenna to be used for non-regenerative repeating in OP104 will be described in detail later.

[0080] In OP105, the control unit 32 instructs the radio devices 31 corresponding to the antennas selected as the transmitting antennas and the receiving antennas in OP104 to transmit or receive. After that, the processing shown in Fig. 7 ends. Thereafter, the relay station 3 performs non-regenerative relay of the data signal transmitted from the base station 2 using the receiving antennas and transmitting antennas selected in OP104.

[0081] 8 is an example of a flowchart of the process of measuring the propagation characteristics between the antennas of the relay station 3. The process shown in FIG. 8 corresponds to the process of OP103 in FIG.

[0082] In OP201, the control unit 32 creates K combinations of antennas for measurement. K is calculated using the above equation 8. The K combinations for measurement are created, for example, using the method described with reference to FIGS. 5 and 6.

[0083] The processes from OP202 to OP204 are executed for each of the K measurement combinations, i.e., the processes from OP202 to OP204 are performed K times.

[0084] In OP202, the control unit 32 causes one or more radio devices 31 corresponding to one or more antennas assigned to the transmitting antenna in the target measurement combination to transmit a reference signal on a control channel from the one or more antennas.

[0085] In OP203, the control unit 32 causes one or more radio devices 31 corresponding to one or more antennas assigned to the receiving antenna in the target measurement combination to receive the reference signal transmitted in OP202.

[0086] In OP204, the control unit 32 measures the propagation characteristics H_(R(n_(k))→R(n_(l))) between one or more antennas assigned to the transmitting antenna in the target measurement combination and one or more antennas assigned to the receiving antenna in the target measurement combination based on the reference signal received in OP203.

[0087] When the processes from OP202 to OP204 are completed for each of the K measurement combinations, the process proceeds to OP104 in FIG.

[0088] 9 is an example of a flowchart of a process for determining the transmitting antenna and the receiving antenna to be used for non-regenerative relaying by the relay station 3. The process shown in FIG. 9 corresponds to the process in OP104 in FIG.

[0089] In OP301, the control unit 32 creates a combination of transmitting antennas and receiving antennas to be used for non-regenerative relay. The number of transmitting antennas and receiving antennas may be a predetermined number, or may be any number within the number of antennas provided in the relay station 3.

[0090] The processes from OP302 to OP303 are performed for all the combinations created in OP301. In OP302, the control unit 32 calculates the amplification gain G_(R) at the relay station 3 for the target combination based on the above formula 4 or formula 4G. In OP303, the control unit 32 calculates the SINR of the received signal at the terminal station 4 for the target combination based on the above formula 7 or formula 7G. When the SINR of the received signal at the terminal station 4 has been calculated for all the combinations created in OP301, the process proceeds to OP304.

[0091] In OP304, the control unit 32 selects the combination that maximizes the SINR of the received signal at the terminal station 4. After that, the process shown in Fig. 9 ends, and the process proceeds to OP105 in Fig. 7.

[0092] So far, we have described how relay station 3 selects the receiving antenna and transmitting antenna to be used for non-regenerative relaying during downlink communication from base station 2 to terminal station 4. However, this is not limiting, and relay station 3 can similarly select the receiving antenna and transmitting antenna to be used for non-regenerative relaying during uplink communication from terminal station 4 to base station 2. In the uplink direction, terminal station 4 is the transmitting station, and base station 2 is the receiving station. Therefore, the above-described technique for determining the receiving antenna and transmitting antenna to be used for non-regenerative relaying at relay station 3 can be applied to uplink communication by replacing base station 2 with terminal station 4 and terminal station 4 with base station 2.

[0093] During uplink communication, the transmission power of the terminal station 4, which is the transmitting station, is obtained by being notified from the control device 1 via, for example, a control channel. The noise power at the base station 2, which is the receiving station, may be, for example, the noise power value at the base station 2 specified in the 5G standard, rather than using the noise power at the relay station 3 as an approximate value.

[0094] <Effects of the First Embodiment> In the first embodiment, the relay station 3 estimates the SINR of the signal received at the terminal station 4, which is the receiving station, and determines the receiving antenna and transmitting antenna to be used for non-regenerative relay so that the SINR is maximized. Therefore, efficient and stable wireless communication can be provided without any need for a wired connection.

[0095] Furthermore, in the first embodiment, the relay station 3 acquires the propagation characteristics between the base station 2, the propagation characteristics between the base station 2 and the terminal station 4, and the propagation characteristics between the antennas by measuring them using a reference signal. The relay station 3 uses the noise power at the relay station 3 as an approximation of the noise power at the terminal station 4 as a receiving station. That is, the relay station 3 can determine the receiving antennas and transmitting antennas to be used for non-regenerative relaying by itself, without using any special communication with the base station 2 and the terminal station 4 to determine the receiving antennas and transmitting antennas to be used for non-regenerative relaying. This makes it possible to reduce the processing load and shorten the processing time involved in determining the receiving antennas and transmitting antennas to be used for non-regenerative relaying.

[0096] Furthermore, in the first embodiment, when the relay station 3 measures the propagation characteristics between antennas, a measurement combination of transmitting antennas and receiving antennas for the reference signal is created so that the number of times the reference signal is transmitted and received is reduced. This makes it possible to reduce the processing load and shorten the processing time involved in measuring the propagation characteristics between antennas, and ultimately to reduce the overall processing load and shorten the processing time for determining the receiving antennas and transmitting antennas to be used for non-regenerative relay.

[0097] Second Embodiment In the first embodiment, the relay station 3 itself determines the receiving antennas and transmitting antennas to be used for non-regenerative relay, but in the second embodiment, the control device 1 determines the receiving antennas and transmitting antennas to be used for non-regenerative relay in the relay station 3. In the second embodiment, descriptions common to the first embodiment will be omitted.

[0098] In the second embodiment, the method by which the control device 1 determines the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3 is the same as the method described in the first embodiment. When the control device 1 determines the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3, it notifies the relay station 3 via a control channel.

[0099] In the second embodiment, the control device 1 cannot measure the propagation characteristics between each antenna of the relay station 3 and the base station 2, the propagation characteristics between each antenna of the relay station 3 and the terminal station 4, and the propagation characteristics between each antenna of the relay station 3. Therefore, the control device 1 instructs the relay station 3 to measure these propagation characteristics and acquires them from the relay station 3.

[0100] Furthermore, in the case of downlink communication, the control device 1 cannot acquire the noise power at the terminal station 4, which is the receiving station. Therefore, the control device 1 may, for example, be notified of the noise power at the relay station 3 together with the measurement results of various propagation characteristics from the relay station 3, and use the noise power at the relay station 3 as an approximation of the noise power at the terminal station 4. Furthermore, the control device 1 may acquire the allowable value of the transmission signal power at the relay station 3 and the amount of suppression of self-interference power at the relay station 3 from the relay station 3 via the control channel prior to the data signal, or may be notified of these together with the various propagation characteristics. Furthermore, the control device 1 may acquire the transmission signal power at the base station 2, which is the transmitting station, from the base station 2, or may use a preset value.

[0101] In the case of uplink communication, the control device 1 uses, for example, the value of noise power at the base station 2 specified in the 5G standard as the noise power at the base station 2 serving as the receiving station. Furthermore, the control device 1 may obtain the allowable value of the transmission signal power at the relay station 3 and the amount of suppression of self-interference power at the relay station 3 from the relay station 3 via a control channel prior to the data signal, or may be notified of these values ​​together with various propagation characteristics. Furthermore, the control device 1 may obtain the transmission signal power at the terminal station 4 serving as the transmitting station via a control channel. The value may be acquired from the terminal station 4 or may be a preset value.

[0102] FIG. 10 is a diagram illustrating an example of the hardware configuration of the control device 1. The control device 1 has a CPU 11, a main memory device 12, and external devices, and executes communication processing and information processing using a computer program. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor, and may have a multi-processor configuration. The CPU 11 may also include a graphics processing unit (GPU), a digital signal processor (DSP), etc. The CPU 11 may also include a field programmable gate array ( The external device may be linked to a hardware circuit such as a FPGA. Examples of the external device include an external storage device 13, an output device 14, an operation device 15, and a communication device 16.

[0103] The CPU 11 executes a computer program that has been loaded in an executable manner into the main memory device 12, and provides processing for the control device 1. The main memory device 12 stores the computer program executed by the CPU 11, data processed by the CPU 11, etc. The main memory device 12 may be a dynamic random access memory (DRAM), a static random access memory (SRAM), etc. , Read Only Memory (ROM), etc. Furthermore, the external storage device 13 is used, for example, as a storage area that assists the main storage device 12, and stores computer programs executed by the CPU 11, data processed by the CPU 11, etc. The external storage device 13 is a hard disk drive, a solid state drive (SSD), etc. Furthermore, the control device 1 is provided with a removable A drive unit for a removable storage medium may be connected. Examples of removable storage media include a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, etc. The CPU 11 is an example of a "control unit" of an "information processing device."

[0104] The output device 14 is, for example, a display device such as a liquid crystal display or an electroluminescence panel. However, the output device 14 may also include a speaker or other device for outputting sound. The operation device 15 is, for example, a touch panel with a touch sensor superimposed on a display. The communication device 16 communicates with the base station 2 and an external network such as the Internet via, for example, optical fiber. The communication device 16 is, for example, a gateway connected to the base station 2 and a gateway that communicates with an external network such as the Internet. The communication device 16 may be a single device or a combination of multiple devices. The hardware configuration of the control device 1 is not limited to that shown in FIG. 10.

[0105] Fig. 11 is an example of a flowchart of a process of determining the receiving antenna and transmitting antenna to be used for non-regenerative relay at the relay station 3 by the control device 1 according to the second embodiment. The process shown in Fig. 11 is started, for example, when a connection request is received from a terminal station 4, and is executed for each radio frame until the communication of the terminal station 4 is completed. The process shown in Fig. 11 is executed by the CPU 11 of the control device 1, but for convenience, the description will be made assuming that the control device 1 is the main entity.

[0106] In OP401, the control device 1 transmits to the relay station 3, via the control channel, an instruction to measure the propagation characteristics between the terminal station 4, the propagation characteristics between the terminal station 4 and the base station 2, and the propagation characteristics between the antennas for all antennas provided at the relay station 3. In OP402, the control device 1 acquires from the relay station 3 the various propagation characteristics that were instructed to be measured in OP401. For example, along with the various propagation characteristics, information such as the number of antennas provided at the relay station 3, the noise power at the relay station 3, and the amount of self-interference power suppression at the relay station 3 is also acquired.

[0107] In OP403, the control device 1 determines the receiving antenna and transmitting antenna to be used for non-regenerative repeating in the relay station 3. The processing of the control device 1 in OP403 is the same as the processing from OP301 to OP304 shown in Fig. 9. In the case of downlink communication, the noise power of the relay station 3 is used as an approximation of the noise power of the terminal station 4. In the case of uplink communication, the base station For the noise power of station 2, for example, the value of the noise power at base station 2 specified in the 5G standard is used.

[0108] In OP404, the control device 1 notifies the relay station 3 of the receiving antenna and transmitting antenna to be used for non-regenerative relay via the control channel. After that, the processing shown in Fig. 11 ends. Note that if there are multiple relay stations 3, the control device 1 executes the processing of Fig. 11 for each relay station 3.

[0109] Fig. 12 is a diagram showing an example of a processing sequence according to the second embodiment. Fig. 12 is an example assuming a communication system 100A. Fig. 12 includes processing sequences of the control device 1, base station 2, relay station 3, and terminal station 4. In a communication system 100B, the base station 2 is separated into a central base station 2A and one or more distributed base stations 2B. However, the processing of the control circuit 22A of the central base station 2A is the same as in Fig. 12. In Fig. 12, transmission and reception of information via a control channel is indicated by a solid line, and transmission and reception of information via a data channel is indicated by a dashed line.

[0110] In S11, a connection request is transmitted from the terminal station 4. The connection request is received by the base station 2 that manages the cell in which the terminal station 4 is located, and is transferred from the base station 2 to the control device 1. In S12, the control device 1 transmits an instruction to the relay station 3 to measure various propagation characteristics (FIG. 11, OP401).

[0111] The base station 2 and the terminal station 4 transmit reference signals at predetermined intervals. In S21, the relay station 3 receives the reference signal from the terminal station 4 and uses the reference signal to measure the propagation characteristics between each antenna and the terminal station 4. In S22, the relay station 3 receives the reference signal from the base station 2 and uses the reference signal to measure the propagation characteristics between each antenna and the base station 2. In S23, the relay station 3 measures the propagation characteristics between each antenna by, for example, performing the process shown in FIG. 8. In S24, the relay station 3 transmits the measured various propagation characteristics to the control device 1. At this time, the relay station 3 may also notify the control device 1 of, for example, the number of antennas at the relay station 3, noise power, and the amount of self-interference power suppression.

[0112] In S31, the control device 1 receives various propagation characteristics and the like from the relay station 3 (FIG. 11, OP402), and determines the receiving antenna and transmitting antenna to be used for non-regenerative relay at the relay station 3 (FIG. 11, OP403). In S32, the control device 1 notifies the relay station 3 of the receiving antenna and transmitting antenna to be used for non-regenerative relay (FIG. 11, OP404).

[0113] In S41, a data signal is transmitted from the base station 2 to the terminal station 4. In S42, the relay station 3 performs non-regenerative relay using the receiving antenna and transmitting antenna notified by the control device 1 in S32.

[0114] According to the second embodiment, the control device 1 can also estimate the SINR at the terminal station 4 without feedback of the SINR from the terminal station 4, which is the receiving station, and efficiently determine the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3.

[0115] In the second embodiment, when measuring the propagation characteristics between the antennas of the relay station 3, the relay station 3 creates K combinations for measurement, but the control device 1 may create the K combinations for measurement and notify the relay station 3. In this case, the control device 1 obtains, for example, the number of antennas of the relay station 3 via a control channel before transmitting an instruction to measure the propagation characteristics.

[0116] In the second embodiment, the control device 1 causes the relay station 3 to measure the propagation characteristics between each antenna and the base station 2 and between each antenna and the terminal station 4, but is not limited to this. For example, the control device 1 causes the base station 2 to measure the propagation characteristics between each antenna of the relay station 3 and the base station 2. For example, the control device 1 may cause the terminal station 4 to measure the propagation characteristics between each antenna of the relay station 3 and the terminal station 4.

[0117] In the second embodiment, the control device 1 determines the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3. However, the present invention is not limited to this, and the base station 2 or the terminal station 4 may determine the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3 instead of the control device 1. The control circuit 22 or the control circuit 22A of the base station 2 or the control circuit 42 of the terminal station 4 executes the processing shown in FIG. 11 , so that the base station 2 or the terminal station 4 can determine the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3.

[0118] When the base station 2 determines the receiving antennas and transmitting antennas to be used for non-regenerative relaying at the relay station 3, the base station 2 may obtain the allowable value of transmission signal power, the amount of self-interference power suppression, and noise power at the relay station 3 from the relay station 3 via a control channel prior to transmitting the data signal, or may be notified by the relay station 3 together with various propagation characteristics, or may obtain these information from the control device 1 if the control device 1 manages this information. Also, when the base station 2 determines the receiving antennas and transmitting antennas to be used for non-regenerative relaying at the relay station 3, the base station 2 may itself measure the propagation characteristics between the base station 2 and each antenna of the relay station 3. Also, the base station 2 may have the terminal station 4 measure the propagation characteristics between each antenna of the relay station 3 and the terminal station 4.

[0119] When the base station 2 determines the receiving antennas and transmitting antennas to be used for non-regenerative relay at the relay station 3 in downlink communications, the base station 2 may obtain the noise power at the terminal station 4 serving as the receiving station directly from the terminal station 4, for example, via a control channel. Alternatively, the base station 2 may be notified of the noise power at the relay station 3 together with various propagation characteristics from the relay station 3, and may use the noise power at the relay station 3 as an approximation of the noise power at the terminal station 4. Because the transmission signal power at the base station 2 is information about the base station 2 itself, the base station 2 uses information previously stored in the memory of the control circuit 22 or the control circuit 22A.

[0120] When the base station 2 determines the receiving antenna and transmitting antenna to be used for non-regenerative relay at the relay station 3 in uplink communication, the base station 2 may obtain the transmission signal power of the terminal station 4 acting as the transmitting station from the terminal station 4, for example, via a control channel, or may obtain it from the control device 1 if the control device 1 manages the information. The noise power of the base station 2 acting as the receiving station is information about the base station 2 itself, and therefore a default value stored in advance in the control circuit 22 or the control circuit 22A of the base station 2 is used.

[0121] When the terminal station 4 determines the receiving antennas and transmitting antennas to be used for non-regenerative relaying at the relay station 3, the terminal station 4 may obtain the allowable value of transmission signal power, the amount of self-interference power suppression, and noise power at the relay station 3 from the relay station 3 via a control channel prior to transmitting the data signal, or may be notified of these values ​​together with various propagation characteristics from the relay station 3, or may obtain these values ​​from the control device 1 if the control device 1 manages this information. Also, when the terminal station 4 determines the receiving antennas and transmitting antennas to be used for non-regenerative relaying at the relay station 3, the terminal station 4 may itself measure the propagation characteristics between the terminal station 4 and each antenna of the relay station 3. Also, the terminal station 4 may have the base station 2 measure the propagation characteristics between each antenna of the relay station 3 and the base station 2.

[0122] When the terminal station 4 determines the receiving antenna and transmitting antenna to be used for non-regenerative relay at the relay station 3 in downlink communication, the terminal station 4 may obtain the transmission signal power of the base station 2 as a transmitting station from the base station 2, for example, through a control channel, or, if the control device 1 manages the information, obtain it from the control device 1 through a control channel. The noise power in the terminal station 4 as a receiving station is information about the terminal station 4 itself, and may be a value stored in the memory of the control circuit 42, for example.

[0123] When the terminal station 4 determines the receiving antenna and transmitting antenna to be used for non-regenerative relay at the relay station 3 in uplink communication, the terminal station 4 may use, for example, a value stored in the memory of the control circuit 42 as the transmission signal power of the terminal station 4 as the transmitting station. Also, the terminal station 4 may use, for example, a value specified in the 5G standard as the noise power of the base station 2 as the receiving station.

[0124] In addition, the communication between the base station 2 and the relay station 3, the communication between the base station 2 and the terminal station 4, and the communication between the relay station 3 and the terminal station 4 on the control channel may each be performed directly or may be performed via the control device 1.

[0125] <Other embodiments> The above-described embodiment is merely an example, and the present disclosure can be implemented with appropriate modifications within the scope that does not deviate from the gist of the disclosure.

[0126] In the first and second embodiments, the base station 2 and the terminal station 4 are described assuming that each has one antenna. However, this is not limited thereto. The base station 2 and the terminal station 4 may each have multiple antennas, and the transmitting station may each have multiple transmitting antennas and the receiving station may each have multiple receiving antennas. When the transmitting station has multiple transmitting antennas and the receiving station has multiple receiving antennas, the propagation characteristics between the transmitting station and the relay station 3 and between the relay station 3 and the receiving station are calculated for each of the antennas. The propagation characteristics between the transmitting station and the relay station 3 and between the relay station 3 and the receiving station are each obtained as a channel matrix. For example, by replacing the propagation characteristics between the transmitting station and the relay station 3 and between the relay station 3 and the receiving station with a channel matrix in Equations 2G to 7G, it is possible to determine the receiving antennas and transmitting antennas used for non-regenerative relaying at the relay station 3 even when the transmitting station has multiple transmitting antennas and the receiving station has multiple receiving antennas.

[0127] Furthermore, the processes and means described in this disclosure can be freely combined and implemented as long as no technical contradictions arise.

[0128] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Alternatively, a process described as being performed by different devices may be executed by one device. In a computer system, the hardware configuration (server configuration) by which each function is realized can be flexibly changed.

[0129] The present disclosure can also be realized by providing a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors in the computer read and execute the program. Such a computer program may be provided to the computer via a non-transitory computer-readable storage medium connectable to the computer's system bus or via a network. Non-transitory computer-readable storage media include any type of medium suitable for storing electronic instructions, such as any type of disk, including magnetic disks (e.g., floppy disks, hard disk drives (HDDs), etc.), optical disks (e.g., CD-ROMs, DVDs, Blu-ray disks), read-only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic cards, flash memory, or optical cards. [Explanation of symbols]

[0130] 1. Control device 2...Base station 3. Relay Station 4. Terminal station 11. CPU 12...Main memory 13...External storage device 16. Communication equipment 21. Radio 22 Control circuit 31. Radio 32 Control section 33 Baseband circuit 41 Radio 42 Control circuit 100 Communication Systems 311··Transmitter 312··Receiver

Claims

1. A plurality of antennas; When relaying a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding it, estimating a signal-to-interference and noise power ratio (SINR) of the first signal after relaying at the receiving station based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station, a second propagation characteristic between the one or more second antennas and the receiving station, noise power and interference power at a relay station, and noise power at the receiving station, when one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after relaying; determining the one or more first antennas and the one or more second antennas in a combination that maximizes the SINR as the receiving antennas and the transmitting antennas, respectively; a control unit that executes the above; A relay station comprising:

2. a first filter that performs filtering to suppress interference between the signal received from the transmitting station and the signal to be transmitted to the receiving station; The control unit creating a plurality of combinations of the one or more first antennas and the one or more second antennas from among the plurality of antennas; calculating the SINR for each of the plurality of combinations based on a transmission power of the first signal at the transmitting station, the first propagation characteristic between the transmitting station and the one or more first antennas, the second propagation characteristic between the one or more second antennas and the receiving station, a transmission power allowable value of the first signal at the relay station, an amount of interference power suppression by the first filter, a third propagation characteristic between the one or more first antennas and the one or more second antennas, noise power at the relay station, and noise power at the receiving station; determining the one or more first antennas as the receiving antennas and the one or more second antennas as the transmitting antennas in the combination that maximizes the SINR at the receiving station; The relay station according to claim 1 .

3. The control unit, for each of the plurality of combinations, calculating an amplification gain at the relay station based on a transmission power of the first signal at the transmitting station, a transmission power allowance of the first signal at the relay station, an interference power suppression amount by the first filter, noise power added at the relay station, the first propagation characteristic between the one or more first antennas and the transmitting station, and the third propagation characteristic between the one or more first antennas and the one or more second antennas; (1) calculating an SINR at the receiving station based on: (1) a transmission power of the first signal at the transmitting station, a received signal power of the first signal after relaying at the receiving station, which is obtained based on the transmission power of the first signal at the transmitting station, the first propagation characteristics between the one or more first antennas and the transmitting station, the amplification gain, and the second propagation characteristics between the one or more second antennas and the receiving station; (2) a received signal power of an interference signal transmitted from the relay station at the receiving station, which is obtained based on the transmission power allowable value of the first signal at the relay station, the third propagation characteristics between the one or more first antennas and the one or more second antennas, an amount of interference power suppression by the first filter, noise power added at the relay station, the amplification gain, and the second propagation characteristics between the one or more second antennas and the receiving station; and (3) noise power at the receiving station. The relay station according to claim 2 .

4. the control unit uses a value of noise power at the relay station as an approximation value of noise power at the receiving station when the transmitting station is a base station and the receiving station is a terminal station. The relay station according to claim 1 .

5. The control unit measuring a first propagation characteristic between each of the plurality of antennas and the transmitting station based on a reference signal from the transmitting station; measuring second propagation characteristics between each of the plurality of antennas and the receiving station based on a reference signal from the receiving station; transmitting a reference signal from at least some of the plurality of antennas and measuring a third propagation characteristic between each of the plurality of antennas; A relay station according to any one of claims 1 to 3.

6. The control unit creating K first combinations of the plurality of antennas, each combination including one or more transmitting antennas that simultaneously transmit reference signals and one or more receiving antennas that simultaneously receive the reference signals transmitted from the one or more transmitting antennas; measuring the third propagation characteristic between each of the plurality of antennas through transmission and reception of the reference signal for each of the K first combinations; K is an integer obtained by rounding up the decimal point of the logarithm with base 2, where N is the number of the plurality of antennas, The K first combinations are created such that a second combination obtained by selecting two antennas, a third antenna and a fourth antenna, from the plurality of antennas does not overlap with either a combination of the third antenna as a transmitting antenna for the reference signal and the fourth antenna as a receiving antenna for the reference signal, or a combination of the fourth antenna as a transmitting antenna for the reference signal and the third antenna as a receiving antenna for the reference signal, among the K first combinations. The relay station according to claim 5 .

7. When a relay station having a plurality of antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding the first signal, one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after the relay, estimating a Signal to Interference and Noise power Ratio (SINR) of the first signal after the relay at the receiving station based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station, a second propagation characteristic between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station; determining the one or more first antennas and the one or more second antennas as the receiving antennas and the transmitting antennas, respectively, in a combination that maximizes the SINR; a control unit that executes An information processing device comprising:

8. the relay station further includes a first filter configured to perform filtering to suppress interference between the signal received from the transmitting station and the signal to be transmitted to the receiving station; The control unit creating a plurality of combinations of the one or more first antennas and the one or more second antennas from among the plurality of antennas; calculating the SINR for each of the plurality of combinations based on a transmission power of the first signal at the transmitting station, the first propagation characteristic between the transmitting station and the one or more first antennas, the second propagation characteristic between the one or more second antennas and the receiving station, a transmission power allowable value of the first signal at the relay station, an amount of interference power suppression by the first filter, a third propagation characteristic between the one or more first antennas and the one or more second antennas, noise power at the relay station, and noise power at the receiving station; determining the one or more first antennas as the receiving antennas and the one or more second antennas as the transmitting antennas in the combination that maximizes the SINR at the receiving station; The information processing device according to claim 7 .

9. The control unit, for each of the plurality of combinations, calculating an amplification gain at the relay station based on a transmission power of the first signal at the transmitting station, a transmission power allowance of the first signal at the relay station, an interference power suppression amount by the first filter, noise power added at the relay station, the first propagation characteristic between the one or more first antennas and the transmitting station, and the third propagation characteristic between the one or more first antennas and the one or more second antennas; (1) calculating an SINR at the receiving station based on: (1) a transmission power of the first signal at the transmitting station, a received signal power of the first signal after relaying at the receiving station, which is obtained based on the transmission power of the first signal at the transmitting station, the first propagation characteristics between the one or more first antennas and the transmitting station, the amplification gain, and the second propagation characteristics between the one or more second antennas and the receiving station; (2) a received signal power of an interference signal transmitted from the relay station at the receiving station, which is obtained based on the transmission power allowable value of the first signal at the relay station, the third propagation characteristics between the one or more first antennas and the one or more second antennas, an amount of interference power suppression by the first filter, noise power added at the relay station, the amplification gain, and the second propagation characteristics between the one or more second antennas and the receiving station; and (3) noise power at the receiving station. The information processing device according to claim 8 .

10. the control unit uses a value of noise power at the relay station as an approximation value of noise power at the receiving station when the transmitting station is a base station and the receiving station is a terminal station. The information processing device according to claim 7 .

11. The control unit instructing the relay station to measure a first propagation characteristic between each of the plurality of antennas and the transmitting station, a second propagation characteristic between each of the plurality of antennas and the receiving station, and a third propagation characteristic between each of the plurality of antennas; The information processing device according to claim 7 .

12. The control unit creating K first combinations of the plurality of antennas, each combination including one or more transmitting antennas that simultaneously transmit reference signals and one or more receiving antennas that simultaneously receive the reference signals transmitted from the one or more transmitting antennas; instructing the relay station to measure the third propagation characteristic between each of the plurality of antennas through transmission and reception of the reference signal for each of the K first combinations; K is an integer obtained by rounding up the decimal point of the logarithm with base 2, where N is the number of the plurality of antennas, Among the K first combinations, a second combination obtained by selecting two antennas, a third antenna and a fourth antenna, from the plurality of antennas is The combination of the third antenna as a transmitting antenna for the reference signal and the fourth antenna as a receiving antenna for the reference signal, and the combination of the fourth antenna as a transmitting antenna for the reference signal and the third antenna as a receiving antenna for the reference signal are created so as not to overlap. The information processing device according to claim 11.

13. The computer When a relay station having a plurality of antennas relays a first signal transmitted from a transmitting station to a receiving station without demodulating or decoding the first signal, one or more first antennas among the plurality of antennas are used as receiving antennas for the first signal and one or more second antennas among the plurality of antennas are used as transmitting antennas for the first signal after the relay, estimating a Signal to Interference and Noise power Ratio (SINR) of the first signal after the relay at the receiving station based on a transmission power of the first signal at the transmitting station, a first propagation characteristic between the one or more first antennas and the transmitting station, a second propagation characteristic between the one or more second antennas and the receiving station, noise power and interference power at the relay station, and noise power at the receiving station; determining the one or more first antennas and the one or more second antennas in a combination that maximizes the SINR as the receiving antennas and the transmitting antennas, respectively; A method comprising:

14. The relay station a first filter that performs filtering to suppress interference between the signal received from the transmitting station and the signal to be transmitted to the receiving station; The computer creating a plurality of combinations of the one or more first antennas and the one or more second antennas from among the plurality of antennas; calculating the SINR for each of the plurality of combinations based on a transmission power of the first signal at the transmitting station, the first propagation characteristic between the transmitting station and the one or more first antennas, the second propagation characteristic between the one or more second antennas and the receiving station, a transmission power allowable value of the first signal at the relay station, an amount of interference power suppression by the first filter, a third propagation characteristic between the one or more first antennas and the one or more second antennas, noise power at the relay station, and noise power at the receiving station; determining the one or more first antennas as the receiving antennas and the one or more second antennas as the transmitting antennas in the combination that maximizes the SINR at the receiving station; The method of claim 13.

15. The computer, for each of the plurality of combinations, calculating an amplification gain at the relay station based on a transmission power of the first signal at the transmitting station, a transmission power allowance of the first signal at the relay station, an interference power suppression amount by the first filter, noise power added at the relay station, the first propagation characteristic between the one or more first antennas and the transmitting station, and the third propagation characteristic between the one or more first antennas and the one or more second antennas; (1) a transmission power of the first signal at the transmitting station, the first propagation characteristic between the one or more first antennas and the transmitting station, the amplification gain, and the second propagation characteristic between the one or more second antennas and the receiving station; a received signal power of the first signal after the relay at the receiving station, which is obtained based on the transmission power of the first signal at the transmitting station, the first propagation characteristic between the one or more first antennas and the transmitting station, the amplification gain, and the second propagation characteristic between the one or more second antennas and the receiving station; (2) a transmission power allowance of the first signal at the relay station, the third propagation characteristic between the one or more first antennas and the one or more second antennas, an amount of interference power suppression by the first filter; (3) calculating an SINR at the receiving station based on received signal power of the interference signal transmitted from the relay station at the receiving station, which is obtained based on added noise power, the amplification gain, and the second propagation characteristics between the one or more second antennas and the receiving station, and (4) the noise power at the receiving station; 15. The method of claim 14.

16. When the transmitting station is a base station and the receiving station is a terminal station, the computer uses a value of noise power at the relay station as an approximation value of noise power at the receiving station. The method of claim 13.

17. The computer provided in the relay station, measuring a first propagation characteristic between each of the plurality of antennas and the transmitting station based on a reference signal from the transmitting station; measuring second propagation characteristics between each of the plurality of antennas and the receiving station based on a reference signal from the receiving station; transmitting a reference signal from at least some of the plurality of antennas and measuring a third propagation characteristic between each of the plurality of antennas; 16. The method according to any one of claims 13 to 15.

18. The computer creating K first combinations of the plurality of antennas, each combination including one or more transmitting antennas that simultaneously transmit reference signals and one or more receiving antennas that simultaneously receive the reference signals transmitted from the one or more transmitting antennas; measuring the third propagation characteristic between each of the plurality of antennas through transmission and reception of the reference signal for each of the K first combinations; K is an integer obtained by rounding up the decimal point of the logarithm with base 2, where N is the number of the plurality of antennas, The K first combinations are created such that a second combination obtained by selecting two antennas, a third antenna and a fourth antenna, from the plurality of antennas does not overlap with either a combination of the third antenna as a transmitting antenna for the reference signal and the fourth antenna as a receiving antenna for the reference signal, or a combination of the fourth antenna as a transmitting antenna for the reference signal and the third antenna as a receiving antenna for the reference signal, among the K first combinations.

18. The method of claim 17.

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