Relay station, transmission method of the relay station, and communication system

Abstract

To improve a diversity effect in a receiving station.SOLUTION: A relay station (3) that can execute a non-reproduction relay against a first radio signal transmitted toward a receiving station (4) having one antenna from a transmission station (2), contains: a plurality of antennas (#0 and #1); a plurality of radio machines (31); and a controller (32). Each of the plurality of radio machines (31) contains: a reception machine (312) that converts a first radio signal received by the antenna to be corresponded into a base band signal; and a transmission machine (311) that converts a signal to which a delay is applied to the base band signal into a second radio signal transmitted toward the receiving station (4) from the antenna to be corresponded. The controller (32) sets a delay amount that is applied to each of the plurality of radio machines (31) so that the delay that is different between the plurality of antennas is applied to the base band signal output by the reception machine in each of the plurality of radio machines (31).SELECTED DRAWING: Figure 3

Description

[Technical field]

[0001] The present disclosure relates to a relay station, a transmission method for a relay station, and a communication system. [Background technology]

[0002] In wireless communication such as the 5th Generation Mobile Communication System (5G), ultra-low latency communication of sub-milliseconds or less is expected. On the other hand, from the viewpoint of improving communication services, it is desirable to expand the coverage area of ​​cells, and relay communication via a relay station is effective for this purpose. Therefore, a wireless communication method has been proposed in which a terminal station that performs wireless communication serves as a relay station. Furthermore, as a relay technology with low latency, non-regenerative relay, in which the relay station does not perform demodulation or decoding, is desirable. [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] H. Chen. AB Gershman, and S. Shahbazpanahi, “Filter-and-Forward Distributed Beamforming in Relay Networks with Frequency Selective Fading”, IEEE Trans. On Signal Processing, vol. 58, no. 3, March 2010. [Non-Patent Document 2] Noguchi, Hayashi, Kaneko, and Sakai, “Single-frequency full-duplex wireless relay for frequency-domain equalization systems,” IEICE Technical Report, vol. SIP2011-109, January 2012. Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present disclosure is to provide a relay station, a transmission method thereof, and a communication system that enable a receiving station to obtain a suitable diversity effect. [Means for solving the problem]

[0005] One aspect of the present disclosure is A relay station capable of performing non-regenerative relay of a first wireless signal transmitted from a transmitting station to a receiving station having one antenna, A plurality of antennas; a plurality of radio devices corresponding to the plurality of antennas, a controller for controlling the operation of the plurality of radio devices; Each of the plurality of radio devices a receiver for converting the first radio signal received by a corresponding antenna into a baseband signal; an FIR filter that adds a delay to the baseband signal; a transmitter that converts the signal output from the FIR filter into a second radio signal that is transmitted from a corresponding antenna to the receiving station; The controller is a relay station that sets different delay amounts in the FIR filters in each of the multiple radio devices so that the FIR filters in each of the multiple radio devices impart different delays between the multiple antennas to the baseband signal input from the receiver.

[0006] Another aspect of the present disclosure is A method for transmitting a relay station having multiple antennas, comprising the steps of: The relay station, receiving a first radio signal transmitted from a transmitting station to a receiving station having one antenna, by each of the plurality of antennas; converting the first radio signal received by each of the plurality of antennas into a baseband signal corresponding to each of the plurality of antennas; applying different delays between the plurality of antennas to each of the baseband signals corresponding to the plurality of antennas using a plurality of FIR filters; converting each of the signals output from each of the plurality of FIR filters into a second radio signal for the receiving station and transmitting the second radio signal from a corresponding antenna; This is a transmission method of a relay station that executes the above.

[0007] Another aspect of the present disclosure is A transmitting station; a receiving station having one antenna; At least one relay station capable of performing non-regenerative relay of a first wireless signal transmitted from the transmitting station to the receiving station; Including, The relay station, A plurality of antennas; a plurality of radio devices corresponding to the plurality of antennas, a controller for controlling the operation of the plurality of radio devices; Each of the plurality of radio devices a receiver for converting the first radio signal received by a corresponding antenna into a baseband signal; an FIR filter that adds a delay to the baseband signal; a transmitter that converts the signal output from the FIR filter into a second radio signal for transmission from a corresponding antenna to the receiving station; The controller is a communication system that sets different delay amounts in the FIR filter in each of the multiple radio devices so that the FIR filter in each of the multiple radio devices imparts different delays between the multiple antennas to the baseband signal input from the receiver. Effect of the Invention

[0008] According to the present disclosure, a receiving station can obtain a favorable diversity effect. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram illustrating a first configuration example of a communication system according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating a second configuration example of the communication system according to the embodiment. [Diagram 3] FIG. 3 is a diagram illustrating an example of a hardware configuration of a relay station. [Figure 4] FIG. 4 is a diagram illustrating an example of the configuration of an FIR filter. [Diagram 5] FIG. 5 is a diagram illustrating an example of a hardware configuration of the control device. [Figure 6] FIG. 6 is an explanatory diagram of the process in the relay station. [Figure 7] FIG. 7 is an explanatory diagram of the process in the relay station. [Figure 8] FIG. 8 is a flowchart showing an example of processing by the control device. [Figure 9] FIG. 9 is a flowchart illustrating an example of processing by the relay station. [Figure 10] FIG. 10 is a flowchart illustrating an example of processing by the relay station. [Figure 11] FIG. 11 is a flowchart illustrating an example of processing performed by a relay station in the first modification. [Figure 12] FIG. 12 is a flowchart illustrating an example of processing performed by a relay station in the first modification. [Figure 13] FIG. 13 is a flowchart illustrating an example of processing performed by the base station in the first modification. [Figure 14] FIG. 14 is a flowchart illustrating an example of processing by the control device in the second modification. [Figure 15] FIG. 15 is a flowchart illustrating an example of processing performed by the base station in the second modification. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] In the Third Generation Partnership Project (3GPP (registered trademark)), In this case, one or more stations (called a BS) provides "transmit diversity (Tx diversity)." Transmit diversity is a function in which a base station uses multiple transmit antennas to transmit signals (called downlink signals) from the base station to terminal stations. With transmit diversity, even if the terminal station has only one antenna, the terminal station can obtain a diversity effect (diversity gain) and improve its SIR (signal-to-interference ratio).

[0011] In a 5G communication system, it is considered that a relay station transmits a wireless signal from a base station to which transmit diversity is applied to a terminal station by non-regenerative relay. In such a case, if there is a high correlation between the propagation characteristics of the wireless signal between the multiple antennas of the relay station and the propagation characteristics of the wireless signal between the base station and the relay station, there is a risk that a sufficient diversity effect cannot be obtained at the terminal station.

[0012] In the present disclosure, a relay station is provided with multiple antennas and FIR filters, and delay diversity is realized for radio signals transmitted from multiple antennas by applying different delay amounts to each antenna in non-regenerative relay. This can improve the diversity gain in the terminal station. However, the configuration of the relay station described later can also be applied to radio signals from a base station (transmitting station) to which transmit diversity is not applied (for example, when a base station uses one antenna to transmit a radio signal to a terminal station having one antenna). In the present disclosure, the term "receiving station having one antenna" includes not only a terminal station having one antenna, but also a terminal station having two or more antennas but using only one antenna to receive radio signals from the transmitting station and relay station.

[0013] The communication system according to the present disclosure may include a transmitting station, a receiving station, at least one (one or more) relay station, and a control device. The transmitting station is, for example, a base station, and the receiving station is, for example, a terminal station. However, the transmitting station may be a terminal station and the receiving station may be a base station. The relay station is, for example, a small base station, a mobile base station, a smartphone, an in-vehicle device, etc. The slot timing of the wireless frame is synchronized between the transmitting station, the receiving station, and the one or more relay stations.

[0014] The relay station performs non-regenerative relay of the radio signal. In non-regenerative relay, the radio signal (first radio signal) received from the transmitting station is converted into a baseband signal, but demodulation and decoding of the baseband signal are not performed. The baseband signal is manipulated, and the manipulated baseband signal is converted into a radio signal and transmitted from an antenna. The relay station according to the present disclosure includes multiple antennas and a radio unit for each antenna, and the non-regenerative relay of the radio signal described above is performed for each antenna and radio unit. In the present disclosure, as an operation on the baseband signal corresponding to each of the multiple antennas, each FIR (Finite Impulse Response) filter included in each radio unit imparts a delay that differs between antennas to each baseband signal. The delay By providing this, delay diversity can be applied to radio signals (second radio signals) transmitted from multiple antennas to a receiving station.

[0015] The relay station includes a controller (control unit), and the controller calculates the amount of delay to be set in the FIR filter included in each wireless device of the relay station. For example, the controller calculates a first propagation delay, which is the propagation delay of the signal received by the relay station from the receiving station, and a second propagation delay, which is the propagation delay of the signal received by the relay station from the transmitting station. The maximum delay is calculated using the second propagation delay, which is the propagation delay of the signal, and the signal processing delay in the relay station, and the delay amount to be set in each FIR filter can be calculated within a range not exceeding the maximum delay. This allows each FIR filter to impart a desired delay, which differs between antennas, to the baseband signal.

[0016] The controller is, for example, a processor such as a computer or a CPU (Central Processing Unit). processor, FPGA (Field Programmable Gate Array) or other arithmetic circuits (integrated circuits), or a combination thereof. The control device provided in the communication system can be configured by the above-mentioned computer, a processor such as a CPU, an integrated circuit, or a combination thereof. The control device gives instructions to the relay station, and the relay station can apply the above-mentioned delay upon receiving the instruction from the control device. It is also conceivable that the control device calculates the amount of delay to be set in each of the above-mentioned FIR filters, includes it in the above-mentioned instruction, and the controller sets the delay amount included in the instruction in each FIR filter.

[0017] The FIR filter according to the present disclosure may perform filtering to suppress interference that occurs in the relay station between a wireless signal received from a transmitting station and a wireless signal to be transmitted to a receiving station. The interference between the signal received from the transmitting station and the signal to be transmitted to the receiving station is also called self-interference (SI). The controller controls the FIR filter to suppress self-interference. It is possible to set weights for

[0018] In addition to the above-mentioned relay station, relay station transmission method, and communication system including the relay station, aspects of the present disclosure can also be specified as a program for causing a relay station to execute the relay station transmission method, and a computer-readable, non-transitory storage medium having the program recorded thereon.

[0019] Hereinafter, an embodiment of the present disclosure will be described based on the drawings. The configurations of the following embodiments are examples, and the present disclosure is not limited to the configurations of the embodiments. In the embodiments, a 5G communication system is exemplified as a communication system, but the configurations of the transmitting station, relay station, and receiving station according to the present disclosure can be applied to communication systems other than 5G (wireless LAN, etc.).

[0020] FIG. 1 is a diagram showing a first configuration example of a communication system. In FIG. 1, a communication system 100A according to the first configuration example has a control device 1, a base station 2, a relay station 3, and a terminal station 4. In FIG. 1, one relay station 3 is shown as an example of at least one relay station, but the communication system 100A may include two or more relay stations 3 (3-1, . . . , 3-N (N is an integer indicating the number of relay stations)) between the base station 2 and the terminal station 4. In addition, in the communication system 100A, the number of terminal stations 4 may be one or more (one terminal station 4 is illustrated in FIG. 1).

[0021] The control device 1 is a device on a network (e.g., a core network) to which the base station 2 is connected. However, it is also possible to consider that the control device 1 is 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, the relay station 3, and the terminal station 4, and provides communication services to the terminal station 4.

[0022] 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 embodiment, the base station 2 has one or more antennas (e.g., antennas #0 and #1), a radio 21 corresponding to each antenna, 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 (base station 2) and wireless communication with the relay station 3 and the terminal station 4 using a computer program on the memory.

[0023] 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, a smartphone, etc. The relay station 3 can be selected as a relay station by the control device 1 from among devices having a configuration capable of non-regenerative relay. When a connection request is generated from the terminal station 4, the control device 1 can select one or more relay stations 3 located within the range of the cell provided by the base station 2, and transmit an instruction to each relay station 3 to non-regeneratively relay the wireless communication. The relay station 3 that receives the instruction operates as the relay station 3 selected by the control device 1.

[0024] Like the base station 2, the relay station 3 has one or more antennas (for example, #0), wireless devices 31 corresponding to each antenna, and a control circuit 32 (an example of a "controller (control unit)").

[0025] 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.

[0026] The terminal station 4 has one antenna (for example, #0) used for receiving radio signals, a radio 41 connected to the antenna, and a control circuit 42. For example, a mobile station in a cell requests the base station 2 to connect to a radio access network, and when the mobile station is connected, the mobile station operates as the terminal station 4. The mobile station in the cell may request the base station 2 directly to connect to the radio access network. Alternatively, the mobile station in the cell may request the base station 2 to connect to the radio access network via a device operating as a relay station 3 in 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.

[0027] FIG. 2 is a diagram showing a second configuration example of the communication system. As the communication system, a communication system 100B according to the second configuration example as shown in FIG. 2 may be applied. The communication system 100B is different from the communication system 100A of FIG. 1 in the following respects. That is, 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 individually distinguished, a branch number is assigned, such as distributed base stations 2B-1, . . . , 2B-K. Here, the branch number K is an integer indicating the number of distributed base stations. In FIG. 2, distributed base stations 2B-1 and 2B-K are illustrated. However, when the distributed base stations 2B-1, . . . , 2B-K are collectively referred to, they are simply described as distributed base station 2B.

[0028] The central base station 2A has a control circuit 22A. The distributed base station 2B has a radio 21B corresponding to the antennas #0 and #1. The control circuit 22A of the central base station 2A and the radio 21B of the distributed base station 2B are connected, for example, by an optical fiber C1 or a wireless network. The topology of the optical fiber C1 connecting the central base station 2A and the 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 as it moves away from the central base station 2A, a star network, a ring network, or the like. In addition, 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 adopted are not limited to a specific one.

[0029] The control circuit 22A has a processor and a memory, similar to the control circuit 22 in Fig. 1. The processor controls communication with the control device 1 and wireless communication with the relay station 3 and the terminal station 4 by using a computer program on the memory. In other words, the control circuit 22A controls wireless communication with the relay station 3 and the terminal station 4 via the wireless device 21B of one or more distributed base stations 2B. Relay station The configurations of the terminal station 3 and the terminal station 4 are the same as those of the communication system 100A, so a repeated explanation will be omitted.

[0030] The communication systems 100A and 100B are premised on the following configuration. In the communication systems 100A and 100B, communication is performed by time division multiplexing, and the same frequency channel is used in the uplink (uplink) and downlink (downlink). Furthermore, the start timing of each slot constituting a wireless frame is synchronized between the base station 2, relay station 3, and terminal station 4.

[0031] In the communication systems 100A and 100B, a block transmission method having a cyclic prefix (CP), such as CP-OFDM (Cyclic Prefix - Orthogonal Frequency Division Multiplexing), is adopted as a wireless modulation method. In this embodiment, a case where CP-OFDM is applied will be described, but a block transmission method having a CP other than CP-OFDM may also be used. In addition, the relay station 3 shares resource block information used in uplink and downlink by the terminal station 4 to be relayed.

[0032] The uplink is a link in the direction from the terminal station 4 to the base station 2. The downlink is a link in the direction from the base station 2 to the terminal station 4. The following description will exemplify a case where non-regenerative relay is performed in the downlink direction. That is, the base station 2 corresponds to the "transmitting station" and the terminal station 4 corresponds to the "receiving station". However, the non-regenerative relay performed by the relay station 3 in the embodiment may also be applied to communication in the uplink direction.

[0033] The relay station 3 applies a delay to the relay signal, that is, the signal (second radio signal) that is non-regeneratively relayed to the terminal station 4. The timing at which the relay signal arrives at the terminal station 4 is calculated in the relay station 3. The relay station 3 calculates a delay time (corresponding to a delay amount) to be applied based on the propagation characteristics of radio waves between the base station 2 and the relay station 3, the propagation characteristics of radio waves between the relay station 3 and the terminal station 4, and the signal processing time at the relay station 3 so that the relay signal transmitted from each antenna (antennas #0 and #1) arrives at the terminal station 4 at a desired timing. The propagation characteristics of radio waves include, for example, a propagation delay, a delay spread, and a phase rotation amount. However, the information included in the propagation characteristics of radio waves is not limited to these. The propagation delay is the time it takes for a signal to arrive at a receiving device after being transmitted from a transmitting device. The delay spread is the time it takes for a signal to arrive at a receiving device after a signal starts arriving at the receiving device until reception of the signal is completed.

[0034] 3 is a diagram showing an example of a hardware configuration of the relay station 3. The relay station 3 includes two antennas #0 and #1 (an example of a plurality of antennas), a plurality of wireless devices 31 (wireless devices 31#0 and 31#1) corresponding to the plurality of antennas (antennas #0 and #1), and a control circuit 32 (an example of a controller). In the following description, when there is no need to distinguish between the wireless device 31#0 and the wireless device 31#1, they are referred to as wireless devices 31.

[0035] The wireless devices 31#0 and 31#1 have the same configuration. That is, the wireless device 31 has a transmitter 311, a receiver 312, and a baseband circuit 313. The transmitter 311 and the receiver 312 are connected to an antenna (#0 or #1) via a circulator 314. That is, the transmitter 311, the receiver 312, and the antenna (#0 or #1) are connected to three ports of the circulator 314. A signal received by the antenna (#0 or #1) is input to the first port of the circulator 314 and transmitted from the second port to the receiver 312. A transmission signal from the transmitter 311 is input to, for example, the third port of the circulator 314 and transmitted from the first port to the antenna (#0 or #1).

[0036] Here, the power difference between the transmission signal and the reception signal is, for example, about 100 dB. On the other hand, the isolation of the circulator 314 is about 30 dB, and a part of the transmission signal is different from the reception signal. The interference between a part of the transmission signal and the reception signal in the radio 31 is called self-interference. Self-interference occurs due to the Radio Frequency (RF) analog filter in the receiver 312. This is suppressed by using the FIR filter 315 included in the baseband circuit 313 in combination.

[0037] The receiver 312 receives a reception signal (for example, a radio signal (first radio signal) from the base station 2) from the antenna (#0 or #1) via the circulator 314. The receiver 312 has a quadrature detection circuit and an analog-to-digital (AD) converter. The receiver 312 down-converts the reception signal by quadrature detection, and further converts it into digital data by the AD converter to obtain a baseband signal. The receiver 312 inputs the obtained baseband signal to the baseband circuit 313.

[0038] The baseband circuit 313 is a digital circuit including an FIR filter 315. A baseband signal is input to the FIR filter 315 as a received signal. The FIR filter 315 suppresses a transmission signal that is mixed into the baseband signal and causes self-interference, and delays the baseband signal by a predetermined delay time. The baseband circuit 313 inputs an output signal of the FIR filter 315 (a signal filtered by the FIR filter 315) to the transmitter 311. In this way, the relay station 3 has a plurality of FIR filters corresponding to a plurality of antennas.

[0039] The transmitter 311 includes a digital-to-analog (DA) converter and a modulation circuit. The transmitter 311 converts a received signal from the baseband circuit 313 into an analog signal, and generates a radio signal (RF signal, for example, a second radio signal to be transmitted to the terminal station 4) by the modulation circuit. The transmitter 311 transmits the radio signal from the antenna (#0 or #1) via the circulator 314 as a relay signal.

[0040] The control circuit 32 can be configured, for example, by a processor such as a CPU, an integrated circuit such as an FPGA, or a combination of these. The control circuit 32 controls non-regenerative repeat processing. More specifically, the control circuit 32 can measure the propagation characteristics of a propagation path, calculate a delay amount corresponding to an antenna, and set a delay amount for the FIR filter 315. The control circuit 32 can also calculate a weight for suppressing self-interference and set the weight in the FIR filter. Setting the weight for suppressing self-interference is optional. The control circuit 32 is an example of a "controller".

[0041] The hardware configuration of the relay station 3 is not limited to that shown in Fig. 3. For example, the relay station 3 may be provided with a separate antenna for a control channel to which the control circuit 32 is connected.

[0042] 4 is a diagram showing a configuration example of the FIR filter 315. The FIR filter 315 is prepared for each antenna #k ​​(k=0, 1, . . . , N_(R)-1). The FIR filter 315 has an input terminal 316, an output terminal 317, and N_(D, k)-stage taps (T1, T2, . . . , TN_(D, k)). The letters in parentheses following the underline after the alphabet correspond to the subscripts in the figure. Each of the taps except tap T1 includes a delay unit (delay element) D that delays the input signal by a delay time τ_(D) and a multiplier ML that multiplies the input signal by a complex weight w_(k).

[0043] Tap T1 does not have a delay device D, and the input signal from the input terminal 316 is weighted by a multiplier ML with a weight w_(1,k). Tap T2 delays the input signal by a delay device D (delay time τ_(D)), and weights it by a multiplier ML with a weight w_(2,k). The same applies to taps T3 and onwards. Therefore, in the final tap TN_(D,k), the input signal to tap T1 (input signal to the FIR filter 315) is given a delay time τ_D×(N_(D,k)-1) and weighted with a weight w_(N_(D,k)). Each tap (T The signals processed by N_(D,k) (T1, T2, ..., TN_(D,k)) are added by adder AD and output from output terminal 317. With the above configuration, the input signal to FIR filter 315 is weighted and averaged, interference signals other than the received signal and noise are removed, and the signal is delayed by a delay time τ_(D) × (N_(D,k)-1).

[0044] The number of taps N_(D,k) and weights w_(k) used by the FIR filter 315, i.e., w_(1,k) to w_(N_(D,k),k), are calculated by the control circuit 32. Details will be described later.

[0045] FIG. 5 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 by computer programs. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor, and may be configured as a multiprocessor. 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 (FPGA), etc. The external device may be linked to a hardware circuit of the above. The external device may be an external storage device 13, an output device 14, an operation device 15, and a communication device 16.

[0046] 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 is a dynamic random access memory (DRAM), a static random access memory (SRAM), a read only memory (ROM), etc. Furthermore, the external memory device 13 is, for example, the main memory device 1 The external storage device 13 is used as a storage area supporting the CPU 2 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. The control device 1 further includes a removable storage medium A drive of the body may be connected to the removable storage medium, for example, a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, etc.

[0047] 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 include a speaker or other device that outputs 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 an optical fiber, for example. 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. 5. The control circuit 32 of the relay station 3 described above may be configured as a device including the CPU 11, the main memory device 12, and the external memory device 13 described above.

[0048] 6 and 7 are explanatory diagrams of the processing in the relay station 3. As shown in Fig. 6, in the relay station 3, the control circuit 32 calculates a delay time Δ_(0) to be applied to the antenna #0 and a delay time Δ_(1) to be applied to the antenna #1. The FIR filters 315 corresponding to the antennas #0 and #1 respectively remove SI (self-interference) and apply a delay time Δ_(0) or Δ_(1) to the input baseband signal, and output the processed signal.

[0049] FIG. 7 shows an example of calculation in the case where the number of antennas of the relay station 3 is two (#0 and #1), the delay time Δ_(0)=0, and Δ_(1)=Δ_(max). and terminal station 4, using CP-OFDM. The delay times Δ_(0) and Δ_(1) are calculated for each radio frame or for each slot constituting a radio frame.

[0050] In CP-OFDM, radio signals arriving at the receiving station during the cyclic prefix (CP) time from the beginning of the slot, i.e., the CP time length (CP length = 5 μsec), are correctly combined, which contributes to improving diversity gain. For this reason, in Fig. 7, the CP length (CP time) is shown as the allowable delay T_(CP).

[0051] 7 indicates a propagation delay in the propagation path of a wireless signal from the base station 2 (BS) to the relay station 3 (R). The propagation delay τ_(BS→R) can be measured (calculated) from a reference signal of a control channel or the like received by the relay station 3 and transmitted from the base station 2 (BS) to the terminal station 4 (UE).

[0052] Furthermore, “τ_(R)” shown in FIG. 7 is the processing delay in the relay station 3 (R), and can be calculated, for example, by the formula “number of delay elements in FIR filter 315 (N_(D,k)−1) × delay time per tap τ_(D)”.

[0053] 7 indicates a propagation delay in the propagation path of a wireless signal from the terminal station 4 (UE) to the relay station 3 (R). The propagation delay τ_(UE→R) can be measured (calculated) from a reference signal, such as a control channel received by the relay station 3 and transmitted from the terminal station 4 (UE) to the base station 2 (BS).

[0054] 7 is a value indicating the measurement deviation and delay spread. When calculating the value of δ for the downlink, it can be calculated through reception of a reference signal between the relay station 3 (R) and the terminal station 4 (UE), and reception of a reference signal from the terminal station 4 (UE) to the base station 2 (BS).

[0055] 7 indicates the maximum value of delay time (maximum delay) that can be applied to the baseband signal input to the FIR filter 315 within the permissible delay T_(CP). The maximum delay Δ_(max) can be calculated, for example, using the formula "Δ_(max)=T_(CP)-(τ_(UE→R)+τ_(R)+τ_(BS→R)+δ)".

[0056] The propagation delay τ_(BS→R), the processing delay τ_(R), the propagation delay τ_(UE→R), δ, and the maximum delay Δ_(max) can be measured and calculated by the control circuit 32. However, the measurements and calculations may be performed by a device other than the control circuit 32.

[0057] The control circuit 32 calculates a different delay time (delay amount) Δ_(k) for each antenna of the relay station 3 (R) so that the inequality "Δ_(k)≦Δ_(max)" is satisfied, and sets Δ_(k) in the FIR filter 315. However, the delay time Δ_(k) is set in the FIR filter 315 in a state where it is discretized by the delay amount (τ_(D)) per tap that the FIR filter 315 has.

[0058] For example, the control circuit 32 can calculate the delay time Δ_(k) for antenna #k, where N_(R) is the number of antennas that the relay station 3 has, by using the formula "Δ_(k)=k·Δ_(max) / (N_(R)-1)". In this case, if the number of antennas is 2, as shown in FIG. 7, the delay time Δ_(0) is 0 and the delay time Δ_(1) is Δ_(max). That is, the transmission timing of the wireless signal (second wireless signal) from antenna #0 is immediately after the end of the processing delay τ_(R), and the transmission timing of the wireless signal (second wireless signal) from antenna #1 is Δ_(ma As a result, the radio signal transmitted from antenna #1 reaches terminal station 4 before τ_(UE→R)+δ has elapsed (the CP time has expired).

[0059] If the number of antennas is three, then Δ_(0) will be 0, Δ_(1) will be Δ_(max) / 2, and Δ_(2) will be Δ_(max). In other words, the delay time Δ_(k) for each antenna is calculated so that the transmission timing of the wireless signal is shifted at equal intervals from the start time of Δ_(max).

[0060] FIG. 8 is a flowchart showing an example of processing by the control device 1. The processing shown in FIG. 8 is performed, for example, by the CPU 11 of the control device 1. In step S01, the control device 1 notifies the relay station 3 of relay permission through a control channel (transmits a message including an instruction for relay permission). The control device 1 also notifies (transmits) identification information of the terminal station 4 (UE) to be relayed by each relay station 3. Step S01 is performed, for example, when the base station 2 (transmitting station) starts transmitting a radio signal to the terminal station 4 (receiving station) using a downlink. At this time, the base station 2 transmits a radio signal to which transmit diversity is applied using multiple antennas (for example, antennas #0 and #1). However, the base station 2 may transmit a radio signal to which transmit diversity is not applied using a single antenna.

[0061] In step S02, the control device 1 determines whether or not a condition for terminating relay permission is satisfied. If it is determined that the condition is satisfied, the process returns to step S01, and if not, the process proceeds to step S03.

[0062] In step S03, the control device 1 performs an end process. For example, the control device 1 stops the notification of relay permission. Alternatively, the control device 1 transmits an instruction to end relay to the relay station 3. Thereafter, the control device 1 ends the process. In this way, the non-regenerative relay by the relay station 3 is performed based on the instruction (relay permission) from the control device 1.

[0063] 9 and 10 are flowcharts showing an example of processing of the relay station 3. The processing shown in Fig. 9 and 10 is executed, for example, by the control circuit 32 of the relay station 3. In addition, the processing shown in Fig. 9 and 10 is started upon receipt of an instruction (control signal) including relay permission from the control device 1.

[0064] In step S001, the control circuit 32 measures the propagation delay τ_(UE→R) of the transmission path of the wireless signal from the terminal station 4 (UE) to the relay station 3 by using a reference signal such as a control channel (control CH) transmitted from the terminal station 4 (UE) to the base station 2 (BS) and received by the relay station 3 (R). When there are multiple (two or more) target terminal stations 4, the control circuit 32 determines the maximum propagation delay as τ_(UE→R).

[0065] In step S002, the control circuit 32 measures the propagation delay τ_(BS→R) of the propagation path of the wireless signal from the base station 2 (BS) to the relay station 3 (R) using a reference signal such as a control CH transmitted from the base station 2 (BS) to the terminal station 4 (UE) and received by the relay station 3 (R).

[0066] In step S003, the control circuit 32 measures the coupling H_(SI) in the self-interference (SI) between the transmitter 311 and the receiver 312 using a reference signal such as a control CH that is received by the relay station 3 and transmitted by the relay station 3 to the base station 2.

[0067] In step S004, the control circuit 32 determines (calculates) the weights w_(k) of the FIR filter 315 for suppressing self-interference, based on the combination H_(SI).

[0068] In step S005, the control circuit 32 determines the number of taps N_(D, k) required for the weighting and The control circuit 32 calculates the processing delay τ_(R) from the delay time τ_(D) per tap. For example, the control circuit 32 calculates τ_(R) using the formula "τ_(R)=(N_(D,k)-1)×τ_(D)".

[0069] Note that the order of the processes from step S001 to step S005 is merely an example, and the order may be changed in any way.

[0070] In step S006, the control circuit 32 calculates the maximum delay Δ_(max) using the permissible delay T_(CP), the propagation delay τ_(UE→R), the propagation delay τ_(BS→R), the processing delay τ_(R), and δ.

[0071] In step S007, the control circuit 32 determines whether the delay time calculation method is a calculation that imparts delays such that the transmission intervals of the wireless signals from each antenna are equal (i.e., the transmission timing occurs at equal intervals) or a calculation that imparts random delays. If the calculation imparts equal delays, the process proceeds to step S008, and if the calculation is random, the process proceeds to step S009. Note that if there are a large number of antennas and it is certain that signals will overlap if they are spaced at equal intervals (Δ_(max) / (N_(R)-1)<δ(delay spread+deviation)), it is possible to switch to random.

[0072] In step S008, the control circuit 32 calculates the delay time for antenna #k ​​for the number N_(R) of antennas of the relay station 3 using the formula "Δ_k=k·Δ_(max) / (N_(R)-1)". After that, the process proceeds to step S010.

[0073] In step S009, the control circuit 32 calculates the delay time using the formula "Δ_(k)=x_(k)·Δ_(max)". At this time, x_(k) is calculated by giving a random variable that follows a uniform distribution (within the range (0,1)).

[0074] In step S010, non-regenerative relay is performed. That is, the control circuit 32 sets the weight w_(k) and the delay time Δ_(k) to each FIR filter 315. In each wireless device 31 (31#0 and 31#1, respectively), the receiver 312 converts a radio signal (first radio signal) from the base station 2 (transmitting station) received by the corresponding antenna #0 or #1 into a baseband signal, and inputs the baseband signal to the corresponding FIR filter 315. The FIR filter 315 performs filtering based on the settings of the weight w_(k) and the delay time Δ_(k). The output signal of the FIR filter 315 is input to the transmitter 311. The transmitter 311 converts the input signal into a radio signal (second radio signal) for the terminal station 4. The second radio signal is radiated (transmitted) from the corresponding antenna #0 or #1. This processing is performed for each slot of the downlink of the wireless frame. However, it is also possible to perform this processing for each slot of the uplink.

[0075] In step S011, the control circuit 32 judges whether the notification of relay permission is continuing, that is, whether the non-regenerative relay process is to be ended. At this time, if it is judged that the non-regenerative relay process is to be ended, the process of Fig. 10 is ended, and if it is judged that the non-regenerative relay process is not to be ended, the process returns to step S001. Note that the parameters (propagation delay, processing delay, and δ) used in the calculation of Δ_(max) are updated in slot units or radio frame units.

[0076] According to an embodiment, each of the communication systems 100A and 100B includes a transmitting station (a base station 2 or a distributed base station 2B-1), a receiving station (a terminal station 4) having one antenna, and at least one relay station 3 capable of performing non-regenerative relay of a first radio signal transmitted from the transmitting station to the receiving station.

[0077] The relay station 3 has multiple antennas (antennas #0 and #1) and The radio communication system includes a plurality of radio devices 31 corresponding to the plurality of radio devices 31 and a controller (control circuit 32) that controls the operation of the plurality of radio devices 31. Each of the plurality of radio devices 31 includes a receiver 312 that converts a first radio signal received from a transmitting station (base station 2 or distributed base station 2B-1) by a corresponding antenna #0 or #1 into a baseband signal, an FIR filter 315 that imparts a delay to the baseband signal, and a transmitter 311 that converts a signal output from the FIR filter 315 into a second radio signal to be transmitted from the corresponding antenna #0 or #1 to a receiving station (terminal station 4). The control circuit 32 (controller) sets different delay times in the FIR filter 315 in each of the plurality of radio devices 31 so that the FIR filter 315 imparts different delays between the plurality of antennas to the baseband signal input from the receiver 312 in each of the plurality of radio devices 31.

[0078] The above-described configuration of the relay station 3 can provide delay diversity to the second radio signal that the relay station 3 transmits to the receiving station using multiple antennas. This allows the receiving station to obtain a diversity effect for the second radio signal, thereby improving the SIR and SINR.

[0079] At this time, when a first radio signal to which transmit diversity using a plurality of antennas is applied is transmitted from a transmitting station (base station 2 or distributed base station 2B-1), a correlation between the propagation characteristics of the first radio signal that directly reaches a receiving station (terminal station 4) and the propagation characteristics of the second radio signal is reduced by providing a different delay for each antenna in the relay station 3. This makes it possible to improve the diversity gain in the receiving station. That is, the receiving station can obtain a suitable diversity effect. On the other hand, even if no transmit diversity gain is obtained for the first radio signal (transmit diversity is not applied), the delay diversity provided to the second radio signal allows the receiving station to obtain a suitable diversity effect.

[0080] In an embodiment, the control circuit 32 (controller) determines a maximum delay Δ_(max) using a first propagation delay (τ_(UE→R)), which is the propagation delay in the propagation path of the radio signal from the receiving station to the relay station 3, a second propagation delay (τ_(BS→R)), which is the propagation delay in the propagation path of the radio signal from the transmitting station to the relay station 3, and the signal processing delay (τ_(R)) at the relay station 3, and can calculate the delay time that each FIR filter 315 imparts to each of the multiple antennas within a range that does not exceed the maximum delay Δ_(max).

[0081] At this time, the control circuit 32 (controller) can calculate the maximum delay Δ_(max) obtained by subtracting at least the first propagation delay (τ_(UE→R)), the second propagation delay (τ_(BS→R)), and the processing delay (τ_(R)) from the cyclic prefix time (CP time, i.e., T_(CP)) used by the relay station 3 for communication with the transmitting station and the receiving station. However, as shown in the calculation formula for Δ_(max), the value of δ may be further subtracted.

[0082] The control circuit 32 (controller) may calculate delay times Δ_(0) and Δ_(1) to be set in each FIR filter 315 provided in the multiple radio devices 31 so that delay times are given at equal intervals for the multiple antennas #0 and #1 (the maximum delay Δ_(max) is divided at equal intervals). In other words, the delay times Δ_(0) and Δ_(1) to be set in each FIR filter 315 may be calculated so that the transmission timings of the radio signals transmitted from each of the multiple antennas #0 and #1 occur at equal intervals.

[0083] Furthermore, the control circuit 32 (controller) may randomly calculate the delay times Δ_(0) and Δ_(1) to be set in each of the FIR filters 315 provided in the multiple wireless devices 31. In other words, the delay time for each antenna may be calculated using a method other than equal intervals.

[0084] Furthermore, the control circuit 32 (controller) in the embodiment performs weighting (setting of weight w_(k)) for the FIR filter 315 so that self-interference related to reception of the first wireless signal and transmission of the second wireless signal is suppressed. This allows for delay addition and suppression of self-interference.

[0085] <Variation 1> The above-described embodiment can be modified as in Modification 1 described below. In the embodiment, parameters (propagation delay, processing delay, etc.) for calculating Δ_(k) are measured or calculated by the control circuit 32 of the relay station 3. Modification 1 describes a case where the delay time Δ_(k) is measured or calculated by the control circuit 22 (FIG. 1) of the base station 2 instead of the control circuit 32 of the relay station 3. The control circuit 22 may be the control circuit 22A (FIG. 2) of the distributed base stations 2B-1 to 2B-k.

[0086] The following describes the differences between the first modification and the embodiment. The operation of the control device 1 in the first modification is the same as that in the embodiment (FIG. 8). In contrast, in the first modification, the processing (operation) in the relay station 3 and the base station 2 is different from that in the embodiment.

[0087] 11 and 12 are flowcharts showing the processing (operation) of the relay station 3 in the first modification, and FIG. 13 is a flowchart showing the processing (operation) of the base station 2 in the first modification.

[0088] In FIG. 11, the processes of steps S001, S003, S004, and S005 are the same as those in the embodiment (FIG. 9). In contrast, in the first modification, steps S005A and S005B are provided instead of step S002. When it is determined that the setting for measuring the propagation delay τ_(BS→R) is set (YES in step S005A), the control circuit 32 of the relay station 3 measures the propagation delay τ_(BS→R) in the same manner as described in step S002. The setting can be performed, for example, by setting a mechanical switch such as a DIP switch, or by switching a software switch such as a flag. The setting is performed, for example, according to an instruction notified from the base station 2 or the control device 1.

[0089] In the first modification, step S005C is further provided. In step S005C, the control circuit 32 of the relay station 3 transmits the propagation delay τ_(UE→R), the processing delay τ_(R), and the number of antennas N_(R) to the base station 2. However, if the propagation delay τ_(BS→R) has been measured in step S005B, the control circuit 32 also transmits the propagation delay τ_(BS→R) to the base station 2.

[0090] In this way, in the first modification, the propagation delay τ_(BS→R) is measured according to the setting. However, the processes of steps S005A and S005B may be optional. Alternatively, a configuration may be adopted in which the propagation delay τ_(BS→R) is measured and transmitted to the base station 2 without step S005A.

[0091] 13, the base station 2 receives the propagation delay τ_(UE→R), the processing delay τ_(R), and the number of antennas N_(R) transmitted from the relay station 3. However, if the propagation delay τ_(BS→R) has been transmitted in step S005C, the propagation delay τ_(BS→R) is also included in the reception parameters.

[0092] In step S102, the control circuit 22 of the base station 2 judges whether or not the propagation delay τ_(BS→R) is included in the received parameters. If it is judged that the propagation delay τ_(BS→R) is included, the process proceeds to step S103, otherwise, If so, the process proceeds to step S104.

[0093] If the process proceeds to step S103, the control circuit 22 acquires the propagation delay τ_(BS→R) from the relay station 3, and proceeds to step S105. If the process proceeds to step S104, the control circuit 22 measures the propagation delay τ_(R→BS) between the relay station 3 and the base station 2 from a reference signal used for notification (transmission) of measurement values ​​(propagation delay τ_(UE→R) and processing delay τ_(R), etc.) from the relay station 3. Thereafter, the process proceeds to step S105.

[0094] In step S105, the control circuit 22 obtains the maximum delay Δ_(max) from the allowable delay T_(CP) based on the measurement value notified from the relay station 3. The maximum delay Δ_(max) is obtained, for example, by the formula Δ_(max)=T_(CP)-(τ_(UE→R)+τ_(R)+τ_(R→BS)+δ. However, if the propagation delay τ_(BS→R) is acquired in step S103, τ_(BS→R) is used in the above formula instead of τ_(R→BS). Note that δ in the formula is a value given in consideration of the measurement deviation and delay spread.

[0095] In step S106, the control circuit 22 calculates a different delay time Δ_(k) for each antenna of the relay station 3 so that Δ_(k)≦Δ_(max) is satisfied, and transmits the delay time Δ_(k) to the relay station 3. The method of calculating the delay time Δ_(k) can be the same as that of the embodiment.

[0096] 12, the relay station 3 receives the delay time Δ_(k) for each antenna transmitted from the base station 2 (YES in S006A). Then, the control circuit 32 of the relay station 3 sets the weight w_(k) and the delay time Δ_(k) for the FIR filter 315 (step S007A) and performs non-regenerative relay (step S008A). The processes in steps S007A and S008A are similar to the process in step S010 in the embodiment (FIG. 10), and therefore a description thereof will be omitted.

[0097] Thus, in the first modification, the control circuit 22 of the base station 2 calculates the delay time Δ_(k) for each antenna and notifies (transmits) it to the relay station 3. The control circuit 32 of the relay station 3 performs non-regenerative relay using the delay time Δ_(k) calculated by the base station 2. Note that in step S008 (step S010), the control circuit 32 determines whether the transmission timing of the signal to the terminal station 4 falls within the CP time (T_(CP)) when received by the terminal station 4, and may stop transmitting the signal if it does not fall within the CP time. The decision to stop may be made by the control circuit 32 of the relay station 3 or by the control circuit 22 of the base station 2.

[0098] Fig. 14 is a flowchart showing an example of processing by the control device 1 in Modification 2, and Fig. 155 is a flowchart showing an example of processing by the base station 2 in Modification 2. In Modification 2, the control device 1 calculates the delay time Δ_(k).

[0099] In the process of the modified example 2 in FIG. 14, steps S01A, S01B, and S01C are provided between step S01 and step S02 in the process (FIG. 8) of the control device 1 in the embodiment.

[0100] In step S01A, the control device 1 receives parameters from the base station 2. In step S01B, the control device 1 calculates Δ_(max) using the parameters. In step S01C, the control device 1 calculates a delay time Δ_(k) for each antenna of the relay station 3. Step S01B is the same process as step S105 in the first modification, and step S01C is the same process as step S016 in the first modification.

[0101] 14 are the same as those in the embodiment, and therefore will not be described. As in the second modification, the calculation of Δ_(max) and Δ_(k) can be performed by the control device 1 on the network that has received (obtained) the parameters for calculation from the base station 2, instead of the control circuit 22.

[0102] In Fig. 15, steps S105A and S106A are provided instead of steps S105 and S106 shown in Fig. 13. In step S105, the propagation delay τ_(UE→R), processing delay τ_(R), number of antennas N_(R), and propagation delay τ_(R→BS) or propagation delay τ_(BS→R) are transmitted to the control device 1 as parameters for calculating Δ_(max) and Δ_(k) of the base station 2.

[0103] In step S106A, the base station 2 receives Δ_(k) for each antenna from the control device 1 and transmits it to the relay station 3. The processes in steps S101 to S104 in FIG. 15 are the same as those in the first modification, and therefore the description will be omitted. The operation of the relay station 3 in the second modification is the same as that in the first modification, and therefore the description will be omitted. As in the second modification, the base station 2 may send a parameter for calculation to the control device 1 (step S105A), receive a calculation result from the control device 1, and send it to the relay station 3. As shown in the first and second modifications, the calculation of the delay time Δ_(k) may be performed by the control circuit 32 (controller) of the relay station 3, may be performed by the control circuit 32 of the base station 2, or may be performed by the control device 1. That is, the relay station 3 may obtain the delay amount (delay time Δ_(k)) calculated in the base station 2 communicating with the relay station 3, or in the control device 1 (network) of the relay station 3.

[0104] The above embodiment is merely an example, and the present disclosure may be modified as appropriate without departing from the spirit and scope of the present disclosure. Furthermore, the processes and means described in the present disclosure may be freely combined and implemented as long as no technical contradiction occurs.

[0105] Furthermore, a process described as being performed by one device may be shared and executed by multiple devices. Or, 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.

[0106] The present disclosure can also be realized by supplying a computer program implementing the functions described in the above embodiments to a computer, and having one or more processors of the computer read and execute the program. Such a computer program may be provided to the computer by a non-transitory computer-readable storage medium connectable to the system bus of the computer, or may be provided to the computer via a network. The non-transitory computer-readable storage medium includes any type of medium suitable for storing electronic instructions, such as, for example, a magnetic disk (e.g., a floppy disk, a hard disk drive (HDD), etc.), an optical disk (e.g., a CD-ROM, a DVD disk, a Blu-ray disk, etc.), a read-only memory (ROM), a random access memory (RAM), an EPROM, an EEPROM, a magnetic card, a flash memory, or an optical card. [Explanation of symbols]

[0107] 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, 31, 41 Radio 22, 32, 42: Control circuit 100A, 100B Communication Systems 311··Transmitter 312··Receiver 313 Baseband circuit 314··Circulator 315··FIR Filter

Claims

1. A relay station capable of performing non-regenerative relay of a first wireless signal transmitted from a transmitting station to a receiving station having one antenna, A plurality of antennas; a plurality of radio devices corresponding to the plurality of antennas, a controller for controlling the operation of the plurality of radio devices; Each of the plurality of radio devices a receiver for converting the first radio signal received by a corresponding antenna into a baseband signal; a transmitter that converts the baseband signal to which a delay has been applied into a second radio signal that is transmitted from a corresponding antenna to the receiving station; The controller sets the amount of delay to be applied in each of the plurality of radio devices so that different delays are applied between the plurality of antennas to the baseband signal output by the receiver in each of the plurality of radio devices. Relay station.

2. The controller obtains a maximum delay using a first propagation delay which is a propagation delay in a propagation path of the radio signal from the receiving station to the relay station, a second propagation delay which is a propagation delay in a propagation path of the radio signal from the transmitting station to the relay station, and a signal processing delay in the relay station, and calculates an amount of delay to be applied in each of the plurality of wireless devices within a range not exceeding the maximum delay. The relay station according to claim 1 .

3. The controller calculates the maximum delay by subtracting at least the first propagation delay, the second propagation delay, and the processing delay from a cyclic prefix time used by the relay station in communication with the transmitting station and the receiving station. The relay station according to claim 2.

4. The controller calculates delay amounts to be applied in the plurality of wireless devices so that delay amounts are applied at equal intervals for the plurality of antennas. The relay station according to claim 2 or 3.

5. The controller randomly calculates the amount of delay to be applied in the plurality of wireless devices. The relay station according to claim 2 or 3.

6. The delay is provided in an FIR filter; The controller performs weighting on the FIR filter so that self-interference related to reception of the first radio signal and transmission of the second radio signal is suppressed. The relay station according to claim 1 .

7. The plurality of antennas receive the first radio signal to which the transmitting station applies transmit diversity using at least one of the antennas. The relay station according to claim 1 .

8. The relay station acquires the delay amount calculated by a base station communicating with the relay station or a control device of the relay station. The relay station according to claim 1 .

9. A method for transmitting a relay station having multiple antennas, comprising the steps of: The relay station, receiving a first radio signal transmitted from a transmitting station to a receiving station having one antenna, by each of the plurality of antennas; converting the first radio signal received by each of the plurality of antennas into a baseband signal corresponding to each of the plurality of antennas; imparting different delays between the plurality of antennas to each of the baseband signals corresponding to the plurality of antennas; converting each of the baseband signals to which different delays have been applied into a second radio signal for the receiving station and transmitting the second radio signal from a corresponding antenna; A relay station transmission method that performs the above.

10. The relay station, obtaining a maximum delay using a first propagation delay which is a propagation delay in a propagation path of the wireless signal from the receiving station to the relay station, a second propagation delay which is a propagation delay in a propagation path of the wireless signal from the transmitting station to the relay station, and a signal processing delay at the relay station; calculating an amount of delay to be applied to each of the plurality of antennas within a range not exceeding the maximum delay; The relay station transmission method of claim 9, further comprising:

11. The calculation of the delay amount includes calculating the maximum delay obtained by subtracting at least the first propagation delay, the second propagation delay, and the processing delay from a cyclic prefix time used by the relay station in communication with the transmitting station and the receiving station. The relay station transmission method according to claim 10.

12. The calculation of the delay amount includes the relay station calculating an amount of delay to be applied to each of the plurality of antennas such that the maximum delay is divided at equal intervals. A relay station transmission method according to claim 10 or 11.

13. The calculation of the delay amount includes the relay station randomly calculating an amount of delay to be applied to each of the plurality of antennas. A relay station transmission method according to claim 10 or 11.

14. The delay is provided in an FIR filter; The relay station weights the FIR filter so that self-interference related to reception of the first radio signal and transmission of the second radio signal is suppressed. The relay station transmission method of claim 9, further comprising:

15. Receiving the first radio signal includes receiving the first radio signal to which transmit diversity has been applied by the transmitting station using at least one antenna. The relay station transmission method according to claim 9.

16. The relay station applies different delays between the plurality of antennas based on delay amounts calculated in a base station communicating with the relay station or in a control device of the relay station. The relay station transmission method according to claim 9.

17. A transmitting station; a receiving station having one antenna; at least one relay station capable of performing non-regenerative relay of a first wireless signal transmitted from the transmitting station to the receiving station; Including, The relay station, A plurality of antennas; a plurality of radio devices corresponding to the plurality of antennas, a controller for controlling the operation of the plurality of radio devices; Each of the plurality of radio devices a receiver for converting the first radio signal received by a corresponding antenna into a baseband signal; a transmitter that converts the baseband signal to which a delay has been applied into a second radio signal to be transmitted from a corresponding antenna to the receiving station; The controller sets the amount of delay to be applied in each of the plurality of radio devices so that different delays are applied between the plurality of antennas to the baseband signal output by the receiver in each of the plurality of radio devices. Communication systems.

18. The controller obtains a maximum delay using a first propagation delay which is a propagation delay in a propagation path of the radio signal from the receiving station to the relay station, a second propagation delay which is a propagation delay in a propagation path of the radio signal from the transmitting station to the relay station, and a signal processing delay in the relay station, and calculates an amount of delay to be applied to each of the plurality of wireless devices within a range not exceeding the maximum delay.

20. The communication system of claim 17.

19. The controller calculates the maximum delay by subtracting at least the first propagation delay, the second propagation delay, and the processing delay from a cyclic prefix time used by the relay station in communication with the transmitting station and the receiving station.

20. The communication system of claim 18.

20. The controller calculates delay amounts to be applied in the plurality of wireless devices such that the maximum delay is divided at equal intervals.

20. A communication system according to claim 18 or 19.

21. The transmitting station transmits the first radio signal to which transmit diversity is applied using at least one antenna.

20. The communication system of claim 17.

22. the transmitting station is a base station that transmits an instruction to the relay station, The relay station applies the delay in response to the instruction received from the base station.

20. The communication system of claim 17.

23. the transmitting station is a base station that transmits an instruction to the relay station, The instruction includes the delay amount calculated in a control device of the base station or the relay station.

20. The communication system of claim 17.

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