JP2024025604A - Communication system, method, relay station, and control device - Google Patents

Abstract

To improve the SNR on a reception side in wireless communication in which a non-regenerative relay is executed.SOLUTION: A communication system comprises a transmitting station, a receiving station, one or more relay stations that relay first signals from the transmitting station to the receiving station without demodulating and decoding the signals, and a control unit. For a first relay station of at least one or more relay stations, so that one or more relay signals of the first signals arrive at the receiving station simultaneously in the same phase after a first time length from the beginning of a slot in a wireless frame, the control unit acquires a first delay time and a first phase rotation amount provided to the first signal through the relay of the first relay station based on the radio wave propagation characteristics between the transmitting station and the first relay station and the radio wave propagation characteristics between the receiving station and the first relay station, and causes the first relay station to provide the first delay time and the first phase rotation amount to the first signal.SELECTED DRAWING: Figure 1

Description

The present disclosure relates to a communication system, method, relay station, and control device.

In wireless communications such as the 5th Generation Mobile Communication System (5G), ultra-low latency communications of sub-milliseconds or less are expected. On the other hand, from the viewpoint of improving communication services, it is desired to expand the coverage area of cells, and relay communication via relay stations is effective for this purpose. Therefore, a wireless communication method has been proposed in which a terminal station that performs wireless communication is used as a relay station. Furthermore, non-regenerative relay, in which demodulation and decoding are not performed at the relay station, is desirable as a relay technique with less delay.

H. Chen. A. B. 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. Noguchi, Hayashi, Kaneko, and Sakai, “Single frequency full-duplex wireless relay for frequency domain equalization system,” IEICE technical report, vol. SIP2011-109, January 2012.

One aspect of the present disclosure provides a communication system, method, relay station, and control device that can improve SNR (Signal-to-Noise Ratio) on the receiving side in wireless communication in which non-regenerative relay is performed. It is to be.

One aspect of the present disclosure is
a transmitting station;
a receiving station,
one or more relay stations that relay a first signal from the transmitting station to the receiving station without demodulating or decoding;
The relay signal of the one or more first signals relayed by the one or more relay stations is synchronized between the transmitting station, the receiving station, and the one or more relay stations. at least a first relay station of the one or more relay stations such that the signals arrive at the receiving station at the same time and in phase after a first time length (Δ_R) from the beginning of a slot in a radio frame in which the signals are transmitted; , by relaying by the first relay station based on the radio wave propagation characteristics between the transmitting station and the first relay station and the radio wave propagation characteristics between the receiving station and the first relay station. A first delay time and a first phase rotation amount given to the first signal are acquired, and the first delay time and a first phase rotation amount given to the first signal are acquired, and the first delay time and the first amount of phase rotation given to the first signal are acquired. The communication system includes a control unit that provides a phase rotation amount.

One of the other aspects of the present disclosure is
The computer is
A relay signal of one or more of the first signals relayed by one or more relay stations that relays the first signal from the transmitting station to the receiving station without demodulating or decoding is transmitted to the transmitting station and the receiving station. and the one or more relay stations, such that the first signal arrives at the receiving station at the same time and in phase a first time length from the beginning of the slot in the transmitted radio frame. and, regarding at least a first relay station of the one or more relay stations, radio wave propagation characteristics between the transmitting station and the first relay station and between the receiving station and the first relay station. obtain a first delay time and a first amount of phase rotation given to the first signal by relaying by the first relay station, based on radio wave propagation characteristics;
causing the first relay station to give the first delay time and the first amount of phase rotation to the first signal;
It's a method.

One of the other aspects of the present disclosure is
In the case of non-regenerative relay in which a first signal from a transmitting station to a receiving station is relayed without demodulating or decoding, the relay signal of the first signal is transmitted to the transmitting station, the receiving station, and one or more relay stations. radio wave propagation between the receiving station and the receiving station such that the first signal arrives at the receiving station after a first length of time from the beginning of the slot in the radio frame in which the first signal is transmitted; obtaining a first delay time based on the characteristic;
obtaining a first phase rotation amount that cancels the phase rotation amount added to the first signal by the relay;
a control unit that executes
a wireless processing unit that provides the first delay time and the first phase rotation amount to the first signal during the non-regenerative relay of the first signal;
It is a relay station equipped with

One aspect of the present disclosure is
One or more relay stations that relay a first signal from a transmitting station to a receiving station without demodulating or decoding the first signal, the relaying signal of the first signal is transmitted between the transmitting station, the receiving station, and the one or more stations. The first signal, which is synchronized with the relay station, arrives at the receiving station at the same time and in phase after a first time length from the beginning of the slot in the transmitted radio frame. When giving a first delay time and a first amount of phase rotation to a signal of obtaining the first time length based on the radio wave propagation characteristics;
a control unit that executes
It is a control device equipped with.

According to one aspect of the present disclosure, in wireless communication in which non-regenerative relay is performed, SNR (Signal-to-Noise Ratio) on the receiving side can be improved.

FIG. 1 is a diagram showing an example of a system configuration of a communication system according to a first embodiment. FIG. 2 is a diagram showing an example of a system configuration of a communication system. FIG. 3 is a diagram illustrating an example of the hardware configuration of a relay station. FIG. 4 is a diagram showing an example of the configuration of the FIR filter according to the first embodiment. FIG. 5 is a diagram illustrating the hardware configuration of the control device. FIG. 6 is a diagram illustrating an example of transmission timing and arrival timing regarding a direct signal from a base station and a relay signal from a relay station. FIG. 7 is an example of a flowchart of processing by the control device. FIG. 8 is an example of a flowchart of processing by the base station. FIG. 9A is an example of a flowchart of processing at a relay station. FIG. 9B is an example of a flowchart of processing at the relay station. FIG. 10A is an example of a processing sequence related to non-regenerative relay according to the first embodiment. FIG. 10B is an example of a sequence of processing related to non-regenerative relay according to the first embodiment. FIG. 11A is an example of a flowchart of processing of the control device according to the second embodiment. FIG. 11B is an example of a flowchart of processing of the control device according to the second embodiment. FIG. 12A is an example of a processing sequence related to non-regenerative relay according to the second embodiment. FIG. 12B is an example of a sequence of processing related to non-regenerative relay according to the second embodiment. FIG. 13A is an example of a processing sequence when the base station determines whether or not the relay station can perform non-regenerative relay, and calculates the delay time and phase rotation amount to be given to the relay signal at the relay station. FIG. 13B is an example of a processing sequence when the base station determines whether or not the relay station can perform non-regenerative relay, and calculates the delay time and phase rotation amount to be given to the relay signal at the relay station.

In non-regenerative relaying, a plurality of relay signals relayed by a plurality of relay stations are given different amounts of phase rotation and different delay times in the radio propagation path, respectively. At the receiving station, these multiple relay signals are received at different times and in different phases, so for example, the amplitudes of the multiple relay signals may be canceled to obtain a sufficient SNR when combined. Sometimes I can't. In view of this, one aspect of the present disclosure aims to improve the SNR obtained when non-regenerative relay is performed at a relay station.

One aspect of the present disclosure is a communication system including a transmitting station, a receiving station, one or more relay stations, and a control unit. For example, the transmitting station is a base station, and the receiving station is a terminal station. However, the present invention is not limited thereto, and 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, a vehicle-mounted device, or the like. The slot timings of radio frames are synchronized between the transmitting station, the receiving station, and one or more relay stations. One or more relay stations perform non-regenerative relaying, in which signals are relayed without demodulating and decoding.

The control unit is, for example, a computer, a processor such as a CPU (Central Processing Unit), or an arithmetic circuit such as an FPGA (Field Programmable Gate Array). For example, the control unit may be included in a relay station, a control device connected to a base station and managing a wireless link, or a base station or a terminal station. The control unit controls relaying by the first relay station for at least the first relay station so that the relay signal of the first signal arrives at the receiving station at the same time and in phase after a first time length from the beginning of the slot. A first delay time and a first phase rotation amount given to the first signal are obtained by: The first signal is a signal transmitted from the transmitting station to the receiving station. For example, when the relay station is equipped with a control section, the first relay station is a relay station that is equipped with the control section. For example, when the control unit is included in the control device, the first relay station is one or more of the one or more relay stations that actually performs relaying.

The control unit calculates the first delay time and the first phase rotation amount based on radio wave propagation characteristics between the transmitting station and the first relay station and radio wave propagation characteristics between the receiving station and the first relay station. Get based on. The first relay station provides a first delay time and a first amount of phase rotation when non-regeneratively relaying the first signal. Radio wave propagation characteristics include, for example, propagation delay, delay spread, and amount of phase rotation. However, the radio wave propagation characteristics are not limited to these.

The first delay time is, for example, based on the propagation delay between the first relay station and the receiving station so that radio waves reach the receiving station from the first relay station after a first time length from the beginning of the slot. This is obtained by calculating backward the transmission timing at the first relay station. More specifically, the control unit relays the first signal after a second time length obtained by subtracting the propagation delay between the first relay station and the receiving station from the first time length from the beginning of the slot. A first delay time is obtained such that the signal is transmitted from the first relay station.

The first amount of phase rotation is determined so as to cancel the amount of phase rotation that the relay signal receives on the radio propagation path, so that the phases of the relay signals relayed by each relay station are aligned. More specifically, the control unit calculates the amount of phase rotation applied at the transmitter of the first relay station from the amount of phase rotation applied at the receiver of the first relay station, and the amount of phase rotation applied at the transmitter of the first relay station from the transmitting station to the first relay station. A value obtained by subtracting the phase rotation applied in the propagation path from the phase rotation amount applied in the propagation path from the first relay station to the receiving station is obtained as the first phase rotation amount.

According to one aspect of the present disclosure, each relay station that relays a first signal from a transmitting station to a receiving station transmits a first signal to a first signal such that the relay signal arrives at the receiving station at the same time and in the same phase. The delay time and the first phase rotation amount are given. As a result, a plurality of relay signals are received at the same time and in the same phase, so that the signal power when the plurality of relay signals are combined becomes the square of the amplitude, so that the SNR at the receiving station can be improved.

In one aspect of the present disclosure, each of the one or more relay stations includes a first filter that performs filtering to suppress interference between a signal received from a transmitting station and a signal transmitted to a receiving station, which occurs at the relay station. It may be equipped with a filter. Interference between a signal received from a transmitting station and a signal transmitted to a receiving station is also called self-interference. The first filter provides a first delay time to the first signal through filtering, and provides a first amount of phase rotation to the filtered first signal. The first filter is, for example, an FIR (Finite Impulse Response) filter.
By filtering the relay signal with the first filter, it is possible to provide the first delay time and the first amount of phase rotation while suppressing self-interference of the relay signal.

In one aspect of the present disclosure, the control unit may determine whether the first relay station can relay the first signal. For example, the control unit may control the relay signal of the first signal transmitted from the first relay station to be transmitted from the beginning of the slot to the receiving station based on the propagation delay between the first relay station and the receiving station. It may be determined whether it is possible to arrive by the time after. If it is determined that the relay signal of the first signal from the first relay station can arrive at the receiving station by the first time after the beginning of the slot, the control unit controls the relay signal of the first signal from the first relay station. It is determined whether the signal of No. 1 is to be relayed. If it is determined that the relay signal of the first signal from the first relay station cannot arrive at the receiving station by the first time after the beginning of the slot, the control unit controls the relay signal of the first signal from the first relay station. It is determined whether or not to relay the signal of No. 1.

Whether or not the relay signal of the first signal transmitted from the first relay station can arrive at the receiving station by the first time from the beginning of the slot is determined, for example, by the communication between the transmitting station and the first relay station. the sum of the propagation delay between, the delay spread between the transmitting station and the first relay station, the processing delay at the first relay station, and the propagation delay between the first relay station and the receiving station. The determination may be made by determining whether the time is less than or equal to the first time length.

According to one aspect of the present disclosure, the relay signal does not reach the receiving station except at the timing after the first time from the beginning of the slot during the cyclic prefix period in which the received signal is equalized. A sufficient SNR can often be obtained. This is because, during the period of the cyclic prefix, the generation of relay signals whose amplitudes cancel each other out can be suppressed by combining the relay signals.

In one aspect of the present disclosure, the communication system may further include a control device that manages a wireless line. The control device obtains a first time length (Δ_R) based on the radio wave propagation characteristics between the transmitting station and the receiving station and the radio wave propagation characteristics between each of the one or more relay stations and the receiving station, One or more relay stations may be notified. The first time length is determined by, for example, the propagation delay between the transmitting station and the receiving station, the delay spread between the transmitting station and the receiving station, and the relay by one of the one or more relay stations. It may be obtained by summing up the delay time that occurs. By obtaining the first time length in this manner, more relay stations can participate in relaying the first signal, and more relay signals can arrive at the receiving station. By having more relay signals arrive at the receiving station at the same time and in phase, the receiving station can obtain a higher SNR.

Another aspect of the present disclosure can also be specified as a method in which a computer executes the processing executed in the communication system. Specifically, the method includes one or more first signals relayed by one or more relay stations, wherein a computer relays a first signal from a transmitting station to a receiving station without demodulating and decoding the first signal. The relay signals are synchronized between the transmitting station, the receiving station, and one or more relay stations, and are simultaneously in phase after a first length of time from the beginning of the slot in the radio frame in which the first signal was transmitted. For the first relay station of at least one relay station, the radio wave propagation characteristics between the transmitting station and the first relay station and the relationship between the receiving station and the first relay station are determined so that the radio wave reaches the receiving station at A first delay time and a first phase rotation given to the first signal by the relay by the first relay station are obtained based on the radio wave propagation characteristics between This is a method of giving the first signal a first delay time and a first amount of phase rotation.

Further, one of the other aspects of the present disclosure can also be specified as a relay station or a control device that executes the processing of the method. In addition, one of the other aspects is to specify it as a program for causing a relay station or a control device to execute the processing of the method, and a computer-readable non-temporary storage medium that records the program. Can be done.

Embodiments of the present disclosure will be described below based on the drawings. The configurations of the following embodiments are illustrative, and the present disclosure is not limited to the configurations of the embodiments.

<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-N), and a terminal station 4. The control device 1 is a device on the 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. A control device 1 controls a base station 2, a relay station 3, and a terminal station 4, and provides communication services to the terminal station 4.

The base station 2 provides the terminal station 4 with a radio access network. An area where wireless communication is possible in a radio access network is also called a cell. In the first embodiment, the base station 2 includes one or more antennas (for example, #0 and #1), a radio device 21 connected to these one or more antennas, and a control circuit 22. The control circuit 22 includes, 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 stored in the memory.

The terminal station 4 is, for example, a mobile station such as a smartphone, a tablet terminal, a wearable terminal, or a vehicle-mounted 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, a terminal device connects to a radio access network within a cell range provided by the base station 2. Relay station 3 relays wireless communication between base station 2 and terminal station 4 . The relay station 3 is, for example, a small base station, a mobile base station, a vehicle-mounted device, a smartphone, or the like. In the first embodiment, the relay station 3 is a device 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 issued from a terminal station 4, control device 1 selects one or more devices located within the range of cells provided by base station 2 as relay station 3 and instructs them to relay wireless communication. In the first embodiment, when a plurality of relay stations 3 are individually distinguished, branch numbers are assigned such as relay stations 3-1, . . . , 3-N. Here, the branch number N is an integer indicating the number of relay station 3 candidates. In FIG. 1, relay stations 3-1 and 3-N are illustrated. However, when the relay stations 3-1, . . . , 3-N are collectively referred to, they are simply written as relay station 3.

Like the base station 2, the relay station 3 includes one or more antennas (for example, #0), a radio device 31 connected to each of the one or more antennas, and a control circuit 32.

The terminal station 4 includes one or more antennas (for example, #0), a radio device 41 connected to the one or more antennas, and a control circuit 42. For example, a mobile station within a cell requests connection to the radio access network from the base station 2, and when connected, the mobile station operates as the terminal station 4. A mobile station within a cell may request a connection to the radio access network directly from the base station 2. Alternatively, a mobile station within a cell may request connection to the radio access network from the base station 2 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 through any one of the one or more relay stations 3 or without going through any of the one or more relay stations 3.

FIG. 2 is a diagram showing an example of the system configuration of the communication system 100B. In the first embodiment, the system configuration may be a communication system 100B. As compared to the communication system 100A of FIG. 1, the communication system 100B includes 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, branch numbers are 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 distributed base stations 2B-1, . . . , 2B-K are collectively referred to, they are simply written as distributed base station 2B.

The central base station 2A has a control circuit 22A. Further, the distributed base station 2B has a radio device 21B. The control circuit 22A of the central base station 2A and the radio device 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 the plurality of 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 away from the central base station 2A, a star network, a ring network, or the like. Further, when connecting the control circuit 22A of the central base station 2A and the radio device 21B of the distributed base station 2B via a wireless network, the standards and protocols of the wireless network to be adopted are not limited to specific ones. .

The control circuit 22A has a processor and a memory like the control circuit 22 in FIG. 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 the terminal station 4 via the radio device 21B of one or more distributed base stations 2B.

In the first embodiment, it is assumed that the communication system 100 employs the following. In the communication system 100, the same frequency channel is used in the uplink and downlink with time division multiplexing. Furthermore, the slot timings of radio frames are synchronized between the base station 2, relay station 3, and terminal station 4. The communication system 100 employs a block transmission method with a cyclic prefix such as CP-OFDM (Cyclic Prefix - Orthogonal Frequency Division Multiplexing) as a wireless modulation method. Furthermore, the relay station 3 shares resource block information used by the terminal station 4 that is the target of relay in 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 in the direction from the base station 2 to the terminal station 4. In the first embodiment, a case will be described in which non-regenerative relay is performed in the downlink direction. That is, in the first embodiment, the transmitting station is the base station 2, and the receiving station is the terminal station 4.

In the first embodiment, each relay station 3 applies a delay and a phase rotation to the relay signal so that the relay signal arrives at the terminal station 4 at the same time and in the same phase. The control device 1 acquires the timing at which the relay signal arrives at the terminal station 4 and notifies each relay station 3 of the timing. Each relay station 3 controls the radio wave propagation characteristics between the base station 2 and the relay station 3 and the radio wave propagation between the relay station 3 and the terminal station 4 so that the relay signal reaches the base station 2 at the notified timing. The delay time given to the relay signal is obtained based on the characteristics. Radio wave propagation characteristics include, for example, propagation delay, delay spread, amount of phase rotation, and the like. However, the information included in the radio wave propagation characteristics is not limited to these. Propagation delay is the time it takes for a signal to reach a receiving device after it is transmitted from a sending device. The delay spread is the time it takes from when a signal begins to reach the receiving device until the reception of the signal is completed.

Each relay station 3 also uses the amount of phase rotation given by the propagation path from base station 2 to relay station 3, the amount of phase rotation given by relay processing at relay station 3, and the amount of phase rotation given by the propagation path from base station 2 to relay station 3, and The amount of phase rotation given to the relay signal is obtained so that the amount of phase rotation given in the propagation path is canceled. As a result, a plurality of relay signals relayed by each relay station 3 arrive at the terminal station 4 at the same time and in the same phase. At the terminal station 4, by combining a plurality of relay signals that arrive at the same time and in the same phase, the amplitude of the combined wave is amplified, thereby increasing the SNR exponentially.

FIG. 3 is a diagram showing an example of the hardware configuration of relay station 3. As shown in FIG. Relay station 3 includes a radio device 31 and a control circuit 32. The radio device 31 of the relay station 3 includes a transmitter 311, a receiver 312, and a baseband circuit 313. The transmitter 311 and receiver 312 are connected to an antenna (#0) via a circulator 314. That is, the transmitter 311, the receiver 312, and the antenna (#0) are connected to three ports of the circulator 314. A transmission signal from the transmitter 311 is input to, for example, a first port of the circulator 314, and is transmitted to the antenna (#0) from the second port. Further, the received signal received by the antenna (#0) is input to the second port of the circulator 314, and is transmitted to the receiver 312 from the third port.

Here, the power difference between the transmitted signal and the received 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 transmitted signal interferes with the received signal. This interference between a part of the transmitted signal and the received signal in the radio device 31 is called self-interference. Self-interference is suppressed by using a Radio Frequency (RF) analog filter in the receiver 312 and an FIR filter in the baseband circuit 313 in combination.

Receiver 312 receives a received signal from antenna (#0) via circulator 314. The receiver 312 has a quadrature detection circuit and an analog-to-digital (AD) converter. The receiver 312 down-converts the received signal using quadrature detection, and further converts it into digital data using an AD converter to obtain a baseband signal. Receiver 312 outputs the obtained baseband signal to baseband circuit 313.

Baseband circuit 313 has an FIR filter. The baseband circuit 313 uses an FIR filter to suppress the transmitted signal that is mixed into the received signal and causes self-interference, and also delays the received signal by a predetermined delay time. The baseband circuit 313 outputs the received signal filtered by the FIR filter to the transmitter 311.

Transmitter 311 includes a digital-to-analog (DA) converter and a modulation circuit. The transmitter 311 converts the received signal from the baseband circuit 313 into an analog signal, and generates an RF signal using a modulation circuit. The transmitter 311 transmits an RF signal as a relay signal from the antenna (#0) via the circulator 314.

The control circuit 32 is, for example, a processor such as a CPU or an arithmetic circuit such as an FPGA. The control circuit 32 controls non-regenerative relay processing. More specifically, the control circuit 32 measures the radio wave propagation characteristics of the propagation path, notifies the control device 1 of the measurement results, and sets the FIR filter. The control circuit 32 is an example of a "control unit" of a "relay station".

Note that the hardware configuration of relay station 3 is not limited to that shown in FIG. 3. For example, relay station 3 may include multiple antennas. When a plurality of antennas are provided, each of the plurality of antennas may be connected to a radio device, or may be connected to one radio device. Further, the relay station 3 may be separately provided with an antenna for a control channel to which the control circuit 32 is connected.

FIG. 4 is a diagram showing an example of the configuration of the FIR filter according to the first embodiment. The FIR filter has N_(D, i) stages of taps (T1, T2, . . . , TN_(D, i)) as a configuration for suppressing self-interference. The characters in parentheses after the underscore after the alphabet correspond to subscripts in the diagram. Tap T1 weights the input signal with weight w_(i, 1) by multiplier ML without passing through delay device D. Tap T2 delays the input signal by delay device D (delay time τ_(D)), and weights it by weight w_(i, 2) by multiplier ML. The same applies to tap T3 and subsequent taps. Therefore, at the final stage tap TN_(D, i), the input signal to tap T1 (input signal to the FIR filter) has a delay of delay time τ_D×(N_(D, i)-1) and a weight A weighting of w_(i, N_(D, i)) is performed. The signals processed by each tap (T1, T2, . . . , TN_(D, i)) are added by an adder AD. With the above configuration, the input signal to the FIR filter is weighted averaged, interference signals other than the received signal and noise are removed, and the signal is delayed by the delay time τ_(D)×(N_(D,i)-1). be done.

In the first embodiment, in addition to the configuration for suppressing the self-interference described above, the FIR filter has a configuration for allowing the relay signal to reach the terminal station 4 at the same time and in the same phase as other relay signals. The FIR filter according to the first embodiment has a delay that further adds a delay to a signal that has been subjected to delay addition and weighted averaging from the first stage tap T1 to the final stage tap TN_(D, i). It has a multiplier Dφ and a multiplier ML that further performs weighting. The delay device Dφ adds a delay time to the signal so that the relay signal reaches the terminal station 4 at the same time as other relay signals. Multiplier ML performs weighting with weight w_(i, N_(D, i+1)). The weight w_(i, N_(D, i+1)) is a weight for imparting phase rotation to the relay signal so that the relay signal reaches the terminal station 4 in the same phase as other relay signals.

The number of taps N_(D, i) used by the FIR filter, the delay time given by the delay device Dφ, and the weight w_(i, 1) to weight w_(i, N_(D, i)+1) are determined by the control circuit. 32. Details will be described later.

FIG. 5 is a diagram illustrating the hardware configuration of the control device 1. As shown in FIG. Control device 1 is CPU 1
1, a main storage device 12, and external equipment, and executes communication processing and information processing using computer programs. The CPU 11 is also called a processor. The CPU 11 is not limited to a single processor, but may have a multiprocessor configuration. Furthermore, the CPU 11 may include a Graphics Processing Unit (GPU), a Digital Signal Processor (DSP), and the like. In addition, the CPU 11 uses a Field Programmable Gate Array (F
It may also be one that cooperates with a hardware circuit such as a PGA (PGA). Examples of the external devices include the external storage device 13, the output device 14, the operating device 15, and the communication device 16.

The CPU 11 executes a computer program loaded in an executable manner in the main storage device 12 and provides processing for the control device 1 . The main storage device 12 stores computer programs executed by the CPU 11, data processed by the CPU 11, and the like. The main storage device 12 includes Dynamic Random Access Memory (DRAM) and Static Random Access Memory (SRAM).
, Read Only Memory (ROM), etc. Further, the external storage device 13 is used, for example, as a storage area to supplement the main storage device 12, and stores computer programs executed by the CPU 11, data processed by the CPU 11, and the like. The external storage device 13 is a hard disk drive, solid state drive (SSD), or the like. Furthermore, a drive device for a removable storage medium may be connected to the control device 1. The removable storage medium is, for example, a Blu-ray disc, a Digital Versatile Disc (DVD), a Compact Disc (CD), a flash memory card, or the like. The CPU 11 is an example of a "control unit" of a "control device."

The output device 14 is, for example, a display device such as a liquid crystal display or an electroluminescent panel. However, the output device 14 may include a speaker or other device that outputs sound. The operating device 15 is, for example, a touch panel in which a touch sensor is stacked on a display. The communication device 16 communicates with the base station 2 and an external network such as the Internet, for example, via an 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. Note that the hardware configuration of the control device 1 is not limited to that shown in FIG. 5.

<Control method>
FIG. 6 is a diagram showing an example of transmission timing and arrival timing regarding a direct signal from the base station 2 and a relay signal from the relay station 3. FIG. 6 shows an example in which non-regenerative relay is performed by two relay stations 3, relay station #0 and relay station #1. That is, in FIG. 6, a direct signal arriving from the base station 2 to the terminal station 4 ("BS→UE" in the figure), a relay signal arriving from relay station #0 to the terminal station 4 ("#0→UE" in the figure) ), and a relay signal arriving at the terminal station 4 from the relay station #1 ("#1→UE" in the figure), which are graphs showing three signals received by the terminal station 4. In each graph shown in FIG. 6, the horizontal axis is time, and the vertical axis is signal reception power. Further, the starting point of each graph shown in FIG. 6 is the head of the slot.

First, since it is assumed that CP-OFDM is adopted in the communication system 100, the direct signal from the base station 2 and the relay signal from each relay station 3 are transmitted to the terminal station during the cyclic prefix length Tcp. You are required to arrive at 4. Therefore, the arrival timing ΔR of the relay signal to the terminal station 4 is set shorter than the cyclic prefix length Tcp. Further, since the direct signal from the base station 2 and the relay signals from each relay station 3 are not in the same phase, if the signals arrive at the terminal station 4 at the same time, the SNR improvement effect may not be sufficiently obtained. Therefore, in order to prevent the direct signal from the base station 2 and the relay signal from each relay station 3 from overlapping, ΔR is the propagation delay τ_(BS→UE) between the base station 2 and the terminal station 4 and the delay spread σ_( BS → UE) is set longer than the total time.

τ＿（Ｒ）は、中継局３における処理遅延と中継局３と端末局４間の伝搬遅延とを考慮した値である。τ＿（Ｒ）は、例えば、複数の中継局３のうち、中継局３における処理遅延及び中継局３と端末局４間の伝搬遅延のそれぞれの最大値の合計に＋αした値である。τ＿（Ｒ）は、制御装置１によって設定される。 Therefore, in the first embodiment, the delay time ΔR from the beginning of the slot, which is the arrival timing of the relay signal to the terminal station 4, is obtained by the following equation (1).

τ_(R) is a value that takes into account the processing delay at the relay station 3 and the propagation delay between the relay station 3 and the terminal station 4. τ_(R) is, for example, a value obtained by adding α to the sum of the respective maximum values of the processing delay at the relay station 3 and the propagation delay between the relay station 3 and the terminal station 4 among the plurality of relay stations 3. τ_(R) is set by the control device 1.

中継局３が中継信号を受信するのは、スロット先頭から基地局２と中継局３との間の伝搬遅延τ＿（ＢＳ→Ｒ，ｉ）と遅延広がりσ＿（ＢＳ→Ｒ，ｉ）との合計時間後である。したがって、中継局３で中継信号に与える遅延時間φｉは下記の式３で取得される。

At the relay station 3, the relay signal is delayed and transmitted so that it reaches the terminal station 4 within ΔR from the beginning of the slot. The transmission timing of the relay signal of the relay station 3, that is, the delay time Δi from the beginning of the slot, is calculated by the following formula (where τ_(UE→R, i) is the propagation delay between the relay station 3 and the terminal station 4). 2). The variable i is a variable indicating the relay station 3, and takes a value from 0 to K-1 (K: the number of relay stations 3).

Relay station 3 receives the relay signal based on the sum of propagation delay τ_(BS→R, i) and delay spread σ_(BS→R, i) between base station 2 and relay station 3 from the beginning of the slot. It's an hour later. Therefore, the delay time φi given to the relay signal by the relay station 3 is obtained by the following equation 3.

The delay time φi given to the relay signal by the relay station 3 is an example of a "first delay time." The delay time ΔR is an example of a "first time length." The propagation delay τ_(UE→R, i) between the relay station 3 and the terminal station 4 is an example of "the propagation delay between the first relay station and the receiving station." The propagation delay τ_(BS→UE) between the base station 2 and the terminal station 4 is an example of "propagation delay between the transmitting station and the receiving station." The delay spread σ_(BS→R, i) between the base station 2 and the terminal station 4 is an example of "delay spread between the transmitting station and the receiving station." τ_(R) is an example of "delay time caused by relay by one relay station among one or more relay stations."

Next, the amount of phase rotation θi given to the relay signals by the relay station 3 in order to make the relay signals arriving at the terminal station 4 have the same phase will be explained. The following amount of phase rotation is added to the relay signal relayed by the relay station 3 before it reaches the terminal station 4.
(1) Amount of phase rotation θ_(BS→R,i) applied on the transmission path between base station 2 and relay station 3
(2) Amount of phase rotation θ_(RX, i) applied by receiver 312 of relay station 3 when receiving a signal from base station 2
(3) Amount of phase rotation θ_(TX,i) applied by transmitter 311 of relay station 3 when transmitting a relay signal from relay station 3
(4) Amount of phase rotation θ_(UE → R, i) applied on the transmission path between relay station 3 and terminal station 4

The phase rotation amount θ_(BS → R, i) and the phase rotation amount θ_(UE → R, i) are measured values measured based on the reference signal transmitted from the base station 2 or the terminal station 4, respectively. be. Therefore, the phase rotation amount θ_(BS→R, i) and the phase rotation amount θ_(UE→R, i) each include the phase rotation amount θ_(RX, i) added at the receiver 312 of the relay station 3. There is. Therefore, the phase rotation amount θi added to the relay signal is obtained by the following equation 4.

The phase rotation amount θi is an example of a "first phase rotation amount." The amount of phase rotation θ_(BS → R, i) applied on the transmission path between base station 2 and relay station 3 is an example of "the amount of phase rotation applied on the transmission path from the transmitting station to the first relay station". be. The amount of phase rotation θ_(UE → R, i) applied on the transmission path between the relay station 3 and the terminal station 4 is an example of "the amount of phase rotation applied on the transmission path from the first relay station to the receiving station." be. The amount of phase rotation θ_(RX,i) applied at the receiver 312 of the relay station 3 is an example of "the amount of phase rotation applied at the receiver." The amount of phase rotation θ_(TX,i) applied by the transmitter 311 is an example of "the amount of phase rotation applied by the transmitter."

<Processing flow>
FIG. 7 is an example of a flowchart of the processing of the control device 1. The process shown in FIG. 7 is started, for example, when a connection request is received from the terminal station 4, and is executed for each radio frame until the communication of the terminal station 4 ends. The CPU 11 of the control device 1 is the main entity that executes the processing shown in FIG. 7, but for convenience, the description will be made with the control device 1 as the main entity.

In OP101, the control device 1 instructs the base station 2 and each relay station 3 to measure radio wave propagation characteristics with the terminal station 4. Radio wave propagation characteristics include, for example, propagation delay, delay spread time, and amount of phase rotation. Note that the selection of the relay station 3 has already been executed before the process shown in FIG.

In OP102, the control device 1 receives the measurement results of the radio wave propagation characteristics between the base station 2 and the terminal station 4. In OP102, the control device 1 obtains the propagation delay τ_(BS→UE) between the base station 2 and the terminal station 4 and the delay spread σ_(BS→UE).

In OP103, the control device 1 receives measurement results of radio wave propagation characteristics between each relay station 3 and the terminal station 4. In OP103, the control device 1 calculates the propagation delay τ_(UE→R, i), the delay spread σ_(UE→R, i), and the phase rotation amount θ_(UE→R, i) between each relay station 3 and the terminal station 4. , i).

In OP104, the control device 1 calculates the delay time ΔR, which is the arrival timing of the relay signal to the terminal station 4. Note that in OP104, the control device 1 may obtain τ_(R) in consideration of the propagation delay between the relay station 3 and the terminal station 4 and the processing delay at the relay station 3.

In OP105, the control device 1 notifies each relay station 3 of the delay time ΔR. Note that communication between the control device 1, base station 2, and each relay station 3 in FIG. 7 is performed through a control channel.

FIG. 8 is an example of a flowchart of processing by the base station 2. The process shown in FIG. 8 is repeatedly executed while the relay station 3 is in operation. The main body that executes the processing shown in FIG. 8 is the control circuit 22 of the base station 2 or the control circuit 22A of the central base station 2A, but for convenience, the description will be made with the base station 2 as the main body.

In OP201, the base station 2 determines whether or not it has received an instruction to measure radio wave propagation characteristics from the control device 1. If an instruction to measure radio wave propagation characteristics is received from the control device 1 (OP201: YES), the process proceeds to OP202. If an instruction to measure radio wave propagation characteristics is received from the control device 1 (OP201: NO), the process shown in FIG. 8 ends.

In OP202, the base station 2 receives a reference signal transmitted from the terminal station 4 at a predetermined period. In OP203, radio wave propagation characteristics between the base station 2 and the terminal station 4 are measured based on the reference signal received in OP202. The radio wave propagation characteristics measured in OP203 include propagation delay τ_(BS→UE) and delay spread σ_(BS→UE) between base station 2 and terminal station 4. In OP204, the base station 2 notifies the control device 1 of the radio wave propagation characteristics between the base station 2 and the terminal station 4.

In OP205, base station 2 transmits a data signal to terminal station 4. Note that transmission and reception of the reference signal of OP202 and notification of radio wave propagation characteristics of OP204 are performed through a control channel. Transmission of the data signal of OP205 is performed through a data channel. Thereafter, the process shown in FIG. 8 ends.

9A and 9B are an example of a flowchart of the processing of the relay station 3. The processes shown in FIGS. 9A and 9B are repeatedly executed while the relay station 3 is in operation. Although the control circuit 32 of the relay station 3 is the main body that executes the processing in FIGS. 9A and 9B, for convenience, the relay station 3 will be described as the main body.

In OP301, relay station 3 determines whether or not it has received an instruction to measure radio wave propagation characteristics from control device 1. If an instruction to measure radio wave propagation characteristics is received from the control device 1 (OP301: YES), the process proceeds to OP302. If an instruction to measure radio wave propagation characteristics has not been received from the control device 1, the process shown in FIG. 9A ends.

In OP302, relay station 3 receives a reference signal transmitted from terminal station 4 at a predetermined period, and measures radio wave propagation characteristics between relay station 3 and terminal station 4 from the reference signal. The radio wave propagation characteristics measured in OP302 include the propagation delay τ_(UE→R, i), delay spread (UE→R, i), and phase rotation amount θ_(UE→R, i) between the relay station 3 and the terminal station 4. R,i) is included. In OP304, relay station 3 notifies control device 1 of the measurement results of radio wave propagation characteristics between relay station 3 and terminal station 4.

In OP304, relay station 3 determines whether notification of delay time ΔR has been received from control device 1. If the notification of the delay time ΔR is received (OP304: YES), the process proceeds to OP305. If the notification of the delay time ΔR has not been received (OP304;:NO), the device enters a standby state.

In OP305, relay station 3 measures the radio wave propagation characteristics between base station 2 and relay station 3 from the reference signal accompanying the signal notifying delay time ΔR in OP304. The radio wave propagation characteristics measured in OP305 include the propagation delay τ_(BS→R, i), delay spread σ_(BS→R, i), and phase rotation amount θ_(BS →R, i) is included.

OP306 to OP308 are processes for determining whether or not to relay the transmission signal of the wireless frame. In OP306, relay station 3 calculates processing delay τ_(R,i) at relay station 3. The processing delay τ_(R, i) is obtained by multiplying the number of taps of the FIR filter minus 1 (N_(D, i)-1) by the delay time τ_(D) per tap. Note that the number of taps N_(D, i) of the FIR filter is obtained, for example, based on the delay spread of self-interference (seconds) and the sampling frequency of the baseband waveform (seconds) so that self-interference is removed. .

In OP307, the relay station 3 calculates the minimum value τ_(min, i) of the timing at which the relay signal arrives at the terminal station 4. τ_(min, i) is calculated using Equation 5 below.

The propagation delay τ_(BS→R,i) between the base station 2 and the relay station 3 is an example of "the propagation delay between the transmitting station and the first relay station." The delay spread σ_(BS→R, i) between the base station 2 and the relay station 3 is an example of "delay spread between the transmitting station and the first relay station." The processing delay τ_(R, i) at the relay station 3 is an example of "the processing delay at the first relay station." The propagation delay τ_(UE→R, i) between the relay station 3 and the terminal station 4 is an example of "the propagation delay between the first relay station and the receiving station." τ_(min, i) is defined as “the propagation delay between the transmitting station and the first relay station, the delay spread between the transmitting station and the first relay station, and the processing delay at the first relay station. , the propagation delay between the first relay station and the receiving station.

In OP308, relay station 3 determines whether τ_(min, i) is less than or equal to ΔR. If τ_(min, i) is less than or equal to ΔR, this indicates that the relay signal from the relay station 3 can arrive at the terminal station 4 by ΔR, and the relay station 3 executes relay processing for the transmission signal of the wireless frame. Determine. In this case, the process advances to OP309 in FIG. 9B. If τ_(min, i) is larger than ΔR, it indicates that the relay signal from the relay station 3 cannot arrive at the terminal station 4 by ΔR, and the relay station 3 executes relay processing of the transmission signal of the wireless frame. Determine not to do so. In this case, the process shown in FIG. 9A ends.

The process shown in FIG. 9B is a process performed when the relay station 3 determines to relay the transmission signal of the wireless frame. In OP309, the relay station 3 measures the coupling matrix H_(SI, i) in self-interference between transmission and reception by transmitting and receiving the reference signal transmitted from the base station 2 and the reference signal transmitted to the base station 2.

In OP310, the relay station 3 obtains the phase rotation amount θ_(RX, i) of the receiver 312 and the phase rotation amount θ_(TX, i) of the transmitter 311 by referring to a lookup table held by the control circuit 32. . The lookup table describes the relationship between setting values such as gain in the transmitter and receiver and the amount of phase rotation.

In OP311, the relay station 3 acquires and sets the weight of each multiplier ML of the FIR filter and the delay time of the delay device Dφ. The delay time φi given to the signal by the FIR filter is determined by the above (Equation 3): the delay time ΔR, the propagation delay τ_(UE→R,i) between the relay station 3 and the terminal station 4, the base station 2 and the relay station 3, the propagation delay τ_(BS→R, i) and the delay spread σ_(BS→R, i). Relay station 3 sets the delay time of delay device Dφ to a value obtained by subtracting processing delay τ_(R, i) in the configuration for suppressing self-interference of the FIR filter from delay time φi.

The respective weights w_(i,L) (L=1,...,N_(D,i)) of the taps T1 to TN_(D,i) of the FIR filter for suppressing self-interference are expressed by the matrix H_ (SI, i). The weight w_(i, L) is calculated using a well-known method. The weight w_(i, N_(D, i+1)) is obtained by the following equation (6) in order to cancel the phase rotation amount θi added to the relay signal.

In OP312, relay station 3 performs non-regenerative relay of the data signal received from base station 2. In OP313, the relay station 3 determines whether or not the relay continues. Relay station 3 continues relaying until it receives an instruction to stop relaying from control device 1 . If the relay continues (OP313: YES), the process advances to OP301 in FIG. 9A. If the relay does not continue (OP313: NO), the process shown in FIG. 9B ends. Note that non-regenerative relay of the data signal of OP 312 is performed through a data channel, and communication with other base stations 2 or terminal stations 4 is performed through a control channel.

FIGS. 10A and 10B are an example of a processing sequence related to non-regenerative relay according to the first embodiment. 10A and 10B are examples assuming a communication system 100A. 10A and 10B include processing sequences of the control device 1, the base station 2, the relay station 3-i, and the terminal station 4. Note that in the 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 similar to that in FIGS. 10A and 10B. In FIGS. 10A and 10B, the transmission and reception of information through the control channel is shown by solid lines, and the transmission and reception of information through the data channel is shown by dashed lines.

In S11, the terminal station 4 transmits a connection request. 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 measure the radio wave propagation characteristics with the terminal station 4 to the base station 2 and the relay station 3-i (FIG. 7, OP101). The base station 2 and the relay station 3-i receive an instruction to measure radio wave propagation characteristics (FIG. 8, OP201: YES, FIG. 9A, OP301: YES).

In S21, the terminal station 4 transmits a reference signal at a predetermined period. In S31, the base station 2 receives the reference signal from the terminal station 4 (FIG. 8, OP202), and uses the reference signal to measure the radio wave propagation characteristics between the base station 2 and the terminal station 4 ( Figure 8, OP203). In S32, the base station 2 transmits the measured radio wave propagation characteristics between the base station 2 and the terminal station 4 to the control device 1 (FIG. 8, OP204). The control device 1 receives the radio wave propagation characteristics between the base station 2 and the terminal station 4 (FIG. 7, OP102). In S41, the relay station 3-i receives the reference signal from the terminal station 4, and uses the reference signal to measure the radio wave propagation characteristics between the relay station 3-i and the terminal station 4 (see FIG. 9A , OP302). In S42, the relay station 3-i transmits the measured radio wave propagation characteristics between the relay station 3-i and the terminal station 4 to the control device 1 (FIG. 9A, OP303). The control device 1 receives the radio wave propagation characteristics between the relay station 3-i and the terminal station 4 (FIG. 7, OP103).

In S51, the control device 1 calculates the delay time ΔR using the radio wave propagation characteristics between the base station 2 and the terminal station 4 and the radio wave propagation characteristics between the relay station 3-i and the terminal station 4. (FIG. 7, OP104). In S52, the control device 1 transmits the delay time ΔR to the relay station 3-i (FIG. 7, OP105). A signal transmitting the delay time ΔR is output from the control device 1 to the base station 2, and is transmitted from the base station 2 to the terminal station 4. Relay station 3-i receives delay time ΔR (FIG. 9A, OP304: YES)

In S53, the relay station 3-i measures the radio wave propagation characteristics between the base station 2 and the relay station 3-i based on the reference signal accompanying the signal notifying the delay time ΔR received from the base station 2. (FIG. 9A, OP305). In S54, the relay station 3-i calculates the minimum value τ_(min, i) of the timing at which the relay signal arrives at the terminal station 4 (FIG. 9A, OP306, OP307). In S55, since τ_(min, i) is less than or equal to the delay time ΔR, the relay station 3-i determines whether to perform relaying in the wireless frame (FIG. 9A, OP308: YES).

In S61 of FIG. 10B, the relay station 3-i and the base station 2 transmit and receive reference signals. In S62, the relay station 3-i measures the coupling matrix H_(SI, i) based on the reference signal transmitted and received between the base stations 2 in S61 (FIG. 9B, OP309). In S63, the relay station 3-i refers to the lookup table held by the control circuit 32 for the phase rotation amount θ_(RX, i) of the receiver 312 and the phase rotation amount θ_(TX, i) of the transmitter 311. (FIG. 9B, OP310). In S64, the relay station 3-i calculates the delay time φi of the FIR filter, the weight w_(i, L) (L=1,..., N_(D, i)), and the weight w_(i, N_(D, i)+1) is calculated and set in the FIR filter (FIG. 9B, OP311).

In S71, the base station 2 transmits a data signal to the terminal station 4 (FIG. 8, OP205). In S72, the relay station 3-i receives the data signal to the terminal station 4 and performs non-regenerative relay (FIG. 9B, OP312). In S73, relay station 3-i transmits the data signal to terminal station 4. More specifically, in the relay station 3-i, the data signal is converted from an analog signal to a digital signal in the receiver 312 to obtain a baseband signal, which is input to the FIR filter. In the FIR filter, the weight w_(i, L) (L=1,..., N_(D, i)) for removing self-interference, the delay time φi, and the amount of phase rotation are used for the relay signal. A weight w_(i, N_(D, i)+1) for giving θi is added. The relay signal is input from the FIR filter to the transmitter 311, converted from a digital signal to an analog signal, and transmitted from the antenna to the terminal station 4.

<Actions and effects of the first embodiment>
In the first embodiment, in each of the plurality of relay stations 3 that perform non-regenerative relay, a delay time and a phase rotation amount are given to the relay signals so that the plurality of relay signals arrive at the terminal station 4 at the same time and in the same phase. . As a result, in the terminal station 4, the SNR is improved by combining the relay signals in the same phase. Furthermore, in the first embodiment, highly accurate phase synchronization is required between the base station 2, relay station 3, and terminal station 4, so that more effects can be obtained in a frequency band of 1 GHz or less, for example.

In the first embodiment, each relay station 3 determines whether to perform non-regenerative relay depending on whether a relay signal can arrive at the terminal station 4 by ΔR from the beginning of the slot. A relay station 3 that cannot have a relay signal arrive at the terminal station 4 at the same time as other relay stations 3 does not perform non-regenerative relay. As a result, relay signals other than relay signals having the same phase do not reach the terminal station 4 at a timing of ΔR from the beginning of the slot, so that a larger SNR can be obtained.

<Second embodiment>
In the first embodiment, the relay station 3 itself calculates the delay time and phase rotation amount to be given to the relay signals so that the plurality of relay signals arrive at the terminal station 4 at the same time and in the same phase. Furthermore, in the first embodiment, the relay station 3 itself determines whether or not to perform non-regenerative relay depending on whether the relay signal can arrive at the terminal station 4 within the delay time ΔR from the beginning of the slot. Determine. In the second embodiment, a device other than the relay station 3 performs these processes. In the second embodiment, explanations common to the first embodiment are omitted.

Similarly to the first embodiment, the system configuration of the second embodiment is either the communication system 100A shown in FIG. 1 or the communication system 100B shown in FIG. 2. Hereinafter, a case will be described in which the control device determines whether or not the relay station 3 can perform non-regenerative relay, and calculates the delay time and phase rotation amount given to the relay signal at the relay station 3. Hereinafter, in the second embodiment, the control device will be denoted by the reference numeral 1B.

FIGS. 11A and 11B are an example of a flowchart of processing of the control device 1B according to the second embodiment. The process shown in FIG. 11 is, for example, similar to the process shown in FIG. 7, started when a connection request is received from the terminal station 4, and is executed for each wireless frame until the communication of the terminal station 4 ends. be done. The CPU 11 of the control device 1B is the main body that executes the processing shown in FIG. 11, but for convenience, the description will be made with the control device 1B as the main body.

Also in the second embodiment, the control device 1B first executes the processes from OP101 to OP104 in FIG. That is, the control device 1B obtains measurements of radio wave propagation characteristics between the base station 2 and each relay station 3 and each terminal station 4, and determines the delay time that is the arrival timing of the relay signal to the terminal station 4. Calculate ΔR.

In OP501, the control device 1B transmits to each relay station 3 an instruction to measure the propagation characteristics between the relay station 3 and the base station 2, and a request for information regarding the FIR filter in the relay station 3. The information regarding the FIR filter is, for example, the number of taps of the FIR filter and the delay time per tap.

In OP502, the control device 1B receives from each relay station 3 the measurement results of radio wave propagation characteristics with the base station 2 and information regarding the FIR filter in the relay station 3. In OP502, the control device 1B determines the propagation delay τ_(BS→R,i) and delay spread σ_(BS →R, i) and the phase rotation amount θ_(BS→R, i). In OP502, the control device 1B acquires the number of taps N_(D, i) of the FIR filter and the delay time τ_(D) per tap as information regarding the FIR filter in the relay station 3.

The processes from OP503 to OP510 are executed for each relay station 3 selected by the control device 1B as a relay station. Hereinafter, the relay station targeted for processing from OP503 to OP510 will be referred to as relay station #i.

OP505 to OP503 are processes for determining whether or not to cause the relay station #i to perform non-regenerative relay of the transmission signal of the wireless frame. In OP503, control device 1B calculates processing delay τ_(R, i) at relay station #i. The processing delay τ_(R, i) is obtained by multiplying the number of taps of the FIR filter minus 1 (N_(D, i)-1) by the delay time τ_(D) per tap.

In OP504, the control device 1B calculates the minimum value τ_(min, i) of the timing at which the relay signal arrives from the relay station #i to the terminal station 4 based on the above (Equation 5).

In OP505, the control device 1B determines whether τ_(min, i) is less than or equal to ΔR. If τ_(min, i) is less than or equal to ΔR (OP505: YES), this indicates that the relay signal transmitted from relay station #i can arrive at the terminal station 4 by ΔR, and the control device 1B It is determined whether station #i executes relay processing for the transmission signal of the wireless frame. In this case, the process advances to OP507 in FIG. 11B.

If τ_(min, i) is larger than ΔR (OP505: NO), it is indicated that the relay signal transmitted from relay station #i cannot reach the terminal station 4 by ΔR, and the control device 1B It is determined that the relay processing of the transmission signal of the wireless frame by station #i is not to be executed. In OP506, the control device 1B notifies the relay station #i of non-implementation of non-regenerative relay through the control channel. After that, the process shown in FIG. 11A ends.

The process shown in FIG. 11B is a process when it is determined that the relay station #i should execute the relay process for the transmission signal of the wireless frame. In OP507 of FIG. 11B, the control device 1B sends the coupling matrix H_(SI, i) in self-interference, the phase rotation amount θ_(RX, i) of the receiver 312, and the phase of the transmitter 311 to the relay station #i. A request for the rotation amount θ_(TX, i) is transmitted.

In OP508, the control device 1B receives from the relay station #i the coupling matrix H_(SI, i) in self-interference between transmission and reception, the phase rotation amount θ_(RX, i) of the receiver 312, and the transmitter 311. The phase rotation amount θ_(TX, i) is received.

In OP509, the control device 1B sets a weight w_(i, N_(D, i+1)) for canceling the delay time in the delay device Dφ and the amount of phase rotation added to the relay signal in the FIR filter of the relay station #i. Calculate. The delay time in the delay device Dφ is obtained by subtracting the processing delay τ_(R, i) from the delay time φi given to the signal by the FIR filter. The delay time φi given to the signal by the FIR filter is determined by the above (Equation 3): the delay time ΔR, the propagation delay τ_(UE→R,i) between the relay station 3 and the terminal station 4, the base station 2 and the relay station 3, the propagation delay τ_(BS→R, i) and the delay spread σ_(BS→R, i). The weight w_(i, N_(D, i+1)) is obtained by the above equation (6).

In OP510, control device 1B notifies relay station #i of the delay time in delay device Dφ and weight w_(i, N_(D, i+1)) calculated in OP509. After that, the process shown in FIG. 11B ends.

FIGS. 12A and 12B are an example of a processing sequence related to non-regenerative relay according to the second embodiment. 12A and 12B are examples assuming a communication system 100A. 12A and 12B include processing sequences of the control device 1B, the base station 2, the relay station 3-i, and the terminal station 4. Although there are a plurality of relay stations 3, relay station 3-i is shown as a representative for convenience. Further, for each relay station 3, the same processing as that for relay station 3-i is performed. Note that in the 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 similar to that in FIGS. 12A and 12B. In FIGS. 12A and 12B, the transmission and reception of information through the control channel is shown by solid lines, and the transmission and reception of information through the data channel is shown by dashed lines.

Steps S111 to S151 are the same as steps S11 to S51 in FIG. 10A. In S152, the control device 1B transmits to the relay station 3-i an instruction to measure radio wave propagation characteristics with the base station 2 and a request for information regarding the FIR filter (FIG. 11A, OP501). The instruction from the control device 1B is transmitted to the base station 2, and from the base station 2 to the relay station 3-i.

In S153, relay station 3-i measures the radio wave propagation characteristics between base station 2 and relay station 3-i based on the reference signal accompanying the signal transmitted from base station 2 in S152. In S154, the relay station 3-i determines the radio wave propagation characteristics between the base station 2 and the relay station 3-i, and information regarding the FIR filter (number of taps of the FIR filter N_(D,i), delay per tap). The time τ_(D)) is transmitted to the control device 1B. The control device 1B receives the radio wave propagation characteristics between the base station 2 and the relay station 3-i and information regarding the FIR filter from the relay station 3-i (FIG. 11A, OP502).

In S155, the control device 1B calculates the minimum value τ_(min, i) of the timing at which the relay signal arrives from the relay station 3-i to the terminal station 4 (FIG. 11A, OP503, OP504).
In S156, since τ_(min, i) is less than or equal to the delay time ΔR, the control device 1B determines whether the relay station 3-i should relay the wireless frame (FIG. 11A, OP505: YES).

In S161 of FIG. 12B, the control device 1B sends to the relay station 3-i the coupling matrix H_(SI, i) in self-interference, the amount of phase rotation θ_(RX, i) of the receiver 312, and the amount of phase rotation θ_(RX, i) of the transmitter 311. A request for the phase rotation amount θ_(TX, i) is transmitted (FIG. 11B, OP507).

In S162, the relay station 3-i and the base station 2 transmit and receive reference signals. In S163, relay station 3-i measures the coupling matrix H_(SI, i) based on the reference signal transmitted and received between base stations 2 in S162. In S164, the relay station 3-i refers to a lookup table held by the control circuit 32 for the phase rotation amount θ_(RX, i) of the receiver 312 and the phase rotation amount θ_(TX, i) of the transmitter 311. and obtain it. In S165, the relay station 3-i sends the coupling matrix H_(SI, i), the phase rotation amount θ_(RX, i) of the receiver 312, and the phase rotation amount θ_(TX) of the transmitter 311 to the control device 1B. , i), and the control device 1B receives these (FIG. 11B, OP508).

In S171, the control device 1B calculates the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter for the relay station 3-i (FIG. 11B, OP509). In S172, the control device 1B notifies the relay station 3-i of the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter (FIG. 11B, OP510).

In S173, the relay station 3-i sets the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter, which are received from the control device 1B, in the FIR filter. Note that the relay station 3-i uses weights w_(i, L) (L=1, ..., N_() for each of the taps T1 to TN_(D, i) of the FIR filter for suppressing self-interference. D,i)) is determined and set based on the matrix H_(SI,i).

In S181, the base station 2 transmits a data signal to the terminal station 4. In S182, relay station 3-i receives the data signal to terminal station 4 and performs non-regenerative relay. In S183, relay station 3-i transmits the data signal to terminal station 4.

From the above, the control device 1B, as a device other than the relay station 3-i, determines whether or not the relay station 3 can perform non-regenerative relay, calculates the delay time and phase rotation amount given to the relay signal at the relay station 3, It can be performed. Note that the processes shown in FIGS. 11A, 11B, 12A, and 12B are examples, and the process is not limited thereto. For example, in OP509 and OP510 of FIG. 11B, the control device 1B calculates the delay time φi given to the signal by the FIR filter of the relay station 3-i, transmits it to the relay station 3-i, and the relay station 3-i The delay time in the delay device Dφ of the filter may be calculated. Alternatively, in OP509 and OP510 of FIG. 11B, the control device 1B controls each weight w_(i, L )(L=1, . . . , N_(D, i)) may be determined based on the matrix H_(SI, i) and notified to the relay station 3-i.

In addition to the control device 1B, the base station 2 or the terminal station 4 determines whether or not the relay station 3 can perform non-regenerative relay, and calculates the delay time and phase rotation amount given to the relay signal at the relay station 3. Good too. The base station 2 or the terminal station 4 can perform the same processing as the control device 1B shown in FIGS. 11A and 11B, for example. τ_(R) used when calculating the delay time ΔR may be set by the base station 2 or the terminal station 4, or may use a predetermined value. In the following, it is assumed that τ_(R) is set by the base station 2 or the terminal station 4.

13A and 13B show processing when the base station 2C determines whether or not the relay station 3 can perform non-regenerative relay, and calculates the delay time and phase rotation amount given to the relay signal at the relay station 3. This is an example of a sequence. 13A and 13B are examples assuming a communication system 100A. 13A and 13B include processing sequences of the control device 1, the base station 2C, the relay station 3-i, and the terminal station 4. Although there are a plurality of relay stations 3, relay station 3-i is shown as a representative for convenience. Further, for each relay station 3, the same processing as that for relay station 3-i is performed. In the communication system 100B, the base station 2 is separated into a central base station 2A and one or more distributed base stations 2B, and the control circuit 22A of the central base station 2A is similar to the base station 2 in FIGS. 13A and 13B. Perform processing. In FIGS. 13A and 13B, the transmission and reception of information through the control channel is shown by solid lines, and the transmission and reception of information through the data channel is shown by dashed lines.

In S201, the terminal station 4 transmits a connection request. The connection request is received by the base station 2C that manages the cell where the terminal station 4 is located, and is transferred from the base station 2C to the control device 1. In S202, the control device 1 notifies the base station 2C of the reception of the connection request from the terminal station 4 and information about the plurality of relay stations 3-i that relay signals to the terminal station 4. At this time, the control device 1 may also notify the base station 2 of τ_(R).

In S211, the base station 2C transmits an instruction to measure the radio wave propagation characteristics with the terminal station 4 to the relay station 3-i (FIG. 7, OP101). Relay station 3-i receives an instruction to measure radio wave propagation characteristics.

In S221, the terminal station 4 transmits a reference signal at a predetermined period. In S231, the base station 2C receives a reference signal from the terminal station 4, and measures the radio wave propagation characteristics between the base station 2C and the terminal station 4 using the reference signal.

In S241, the relay station 3-i receives the reference signal from the terminal station 4, and measures the radio wave propagation characteristics between the relay station 3-i and the terminal station 4 using the reference signal. In S242, the relay station 3-i transmits the measured radio wave propagation characteristics between the relay station 3-i and the terminal station 4 to the base station 2. The base station 2C receives the radio wave propagation characteristics between the relay station 3-i and the terminal station 4 (FIG. 7, OP103).

In S251, the base station 2C calculates the delay time ΔR using the radio wave propagation characteristics between the base station 2C and the terminal station 4 and the radio wave propagation characteristics between the relay station 3-i and the terminal station 4. (FIG. 7, OP104). In S252, the base station 2C transmits to the relay station 3-i an instruction to measure radio wave propagation characteristics with the base station 2C and a request for information regarding the FIR filter (FIG. 11A, OP501).

In S253, relay station 3-i measures the radio wave propagation characteristics between base station 2C and relay station 3-i based on the reference signal accompanying the signal transmitted from base station 2C in S252. In S254, the relay station 3-i determines the radio wave propagation characteristics between the base station 2C and the relay station 3-i, and information regarding the FIR filter (number of taps of the FIR filter N_(D, i), delay per tap). The time τ_(D)) is transmitted to the base station 2C. The base station 2C receives the radio wave propagation characteristics between the base station 2 and the relay station 3-i and information regarding the FIR filter from the relay station 3-i (FIG. 11A, OP502).

In S255, the base station 2C calculates the minimum value τ_(min, i) of the timing at which the relay signal arrives from the relay station 3-i to the terminal station 4 (FIG. 11A, OP503, OP504). In S256, since τ_(min, i) is less than or equal to the delay time ΔR, the base station 2C determines whether the relay station 3-i should relay the wireless frame (FIG. 11A, OP505: YES).

In S261 of FIG. 13B, the base station 2C sends to the relay station 3-i the coupling matrix H_(SI, i) in self-interference, the amount of phase rotation θ_(RX, i) of the receiver 312, and the amount of phase rotation θ_(RX, i) of the transmitter 311. A request for the phase rotation amount θ_(TX, i) is transmitted (FIG. 11B, OP507).

In S262, the relay station 3-i and the base station 2 transmit and receive reference signals. In S263, relay station 3-i measures the coupling matrix H_(SI, i) based on the reference signal transmitted and received between base stations 2 in S262. In S264, the relay station 3-i refers to the lookup table held by the control circuit 32 for the phase rotation amount θ_(RX, i) of the receiver 312 and the phase rotation amount θ_(TX, i) of the transmitter 311. and obtain it. In S265, the relay station 3-i sends the coupling matrix H_(SI, i), the phase rotation amount θ_(RX, i) of the receiver 312, and the phase rotation amount θ_(TX) of the transmitter 311 to the base station 2C. , i), and the base station 2C receives these (FIG. 11B, OP508).

In S271, the base station 2C calculates the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter for the relay station 3-i (FIG. 11B, OP509). In S272, the base station 2C notifies the relay station 3-i of the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter (FIG. 11B, OP510).

In S273, the relay station 3-i sets the delay time and weight w_(i, N_(D, i)+1) in the delay device Dφ of the FIR filter, which are received from the base station 2C, in the FIR filter. Note that the relay station 3-i uses weights w_(i, L) (L=1, ..., N_() for each of the taps T1 to TN_(D, i) of the FIR filter for suppressing self-interference. D,i)) is determined and set based on the matrix H_(SI,i). Thereafter, the relay station 3-i performs non-regenerative relay of the data signal from the base station 2 in the same manner as S181 to S183 in FIG. 12B.

13A and 13B, the base station 2C, as a device other than the relay station 3-i, determines whether or not the relay station 3 can perform non-regenerative relay, and determines the delay time and phase rotation amount given to the relay signal at the relay station 3. It is possible to calculate and. Note that the processing shown in FIGS. 13A and 13B is an example, and the processing is not limited thereto. For example, the acquisition of the radio wave propagation characteristics between the base station 2C and the relay station 3-i from the relay station 3-i in S252 to S254 in FIG. 13 may be performed by the base station 2C itself.

When the terminal station 4 determines whether or not the relay station 3 can perform non-regenerative relay, and calculates the delay time and phase rotation amount given to the relay signal at the relay station 3, the terminal station 4 requests connection. After transmitting, for example, information on the base station 2 and the plurality of relay stations 3 may be acquired from the control device 1, and thereafter, the same processing as the base station 2C after S211 in FIG. 13A may be performed. Further, in this case, the radio wave propagation characteristics between the terminal station 4 and the base station 2 and the radio wave propagation characteristics between the terminal station 4 and the relay station 3 may be measured by the terminal station 4 itself.

In addition, some or all of the control device 1, the base station 2, and the terminal station 4 cooperate to determine whether or not the relay station 3 can perform non-regenerative relay, and to determine the delay time given to the relay signal at the relay station 3. You may also calculate the amount of phase rotation. For example, the control device 1 calculates the delay time ΔR, and the base station 2 or the terminal station 4 determines whether or not the relay station 3 can perform non-regenerative relay, and determines the delay time and phase rotation amount given to the relay signal at the relay station 3. may also be calculated. For example, the control device 1 calculates the delay time ΔR, the base station 2 determines whether the relay station 3 can perform non-regenerative relay, and the terminal station 4 calculates the delay time and phase rotation amount given to the relay signal at the relay station 3. may be calculated.

<Modified example>

In the first and second embodiments, non-regenerative relaying in the downlink direction has been described, but the same can be applied to non-regenerative relaying in the uplink direction. In the case of the uplink direction, the transmitting station is the terminal station 4 and the receiving station is the base station 2.

Create multiple groups with multiple relay stations 3, set the arrival timing ΔR of the relay signal to the terminal station 4 for each group, and have the relay signals arrive at the terminal station 4 with the same phase at different timings for each group. You can do it like this.

Although the first and second embodiments have been described assuming that the relay station 3 is provided with one antenna, the relay station 3 may be provided with a plurality of antennas. When the relay station 3 includes a plurality of antennas, the relay station 3 determines whether non-regenerative relay can be performed for each antenna. Further, when one radio device is connected to one antenna, the relay station 3 obtains the delay time and phase rotation amount given to the relay signal for each antenna.

In the first embodiment, each relay station 3 calculates the delay time and phase rotation amount given to the relay signal, but the control device 1 calculates these for each relay station 3 and notifies each relay station 3. good. In this case, the control device 1 receives from each relay station 3 the amount of phase rotation θ_(RX, i) of the receiver 312, the amount of phase rotation θ_(TX, i) of the transmitter 311, and the amount of phase rotation θ_(TX, i) of the receiver 312. The propagation delay with the terminal station 4 is notified.

<Other embodiments>
The above-described embodiments are merely examples, and the present disclosure may be implemented with appropriate changes within the scope of the invention. Furthermore, the processes and means described in this disclosure can be implemented in any combination as long as no technical contradiction occurs.

Further, the processing described as being performed by one device may be shared and executed by a plurality of devices. Alternatively, processes described as being performed by different devices may be performed by one device. In a computer system, the hardware configuration (server configuration) that implements each function can be flexibly changed.

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 included in 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 computer's system bus, or may be provided to the computer via a network. The non-transitory computer-readable storage medium may be any type of disk, such as, for example, a magnetic disk (floppy disk, hard disk drive (HDD), etc.), an optical disk (CD-ROM, DVD disk, Blu-ray disk, etc.); Includes any type of medium suitable for storing electronic instructions, such as read only memory (ROM), random access memory (RAM), EPROM, EEPROM, magnetic card, flash memory, or optical card.

1...Control device 2...Base station 3...Relay station 4...Terminal station 11...CPU
12... Main storage device 13... External storage device 16... Communication devices 21, 31, 41... Radio equipment 22, 32, 42... Control circuit 100... Communication system 311... Transmitter 312... Receiver 313...Baseband circuit 314...Circulator

Claims (20)

a transmitting station;
a receiving station,
one or more relay stations that relay a first signal from the transmitting station to the receiving station without demodulating or decoding;
The relay signal of the one or more first signals relayed by the one or more relay stations is synchronized between the transmitting station, the receiving station, and the one or more relay stations. for at least the first relay station of the one or more relay stations, such that the signals arrive at the receiving station at the same time and in phase after a first length of time from the beginning of the slot in the radio frame in which the signals are transmitted. Based on the radio wave propagation characteristics between the transmitting station and the first relay station and the radio wave propagation characteristics between the receiving station and the first relay station, the first relay station is relayed by the first relay station. acquires a first delay time and a first amount of phase rotation given to the signal, and transmits the first delay time and first amount of phase rotation given to the first signal to the first relay station. a control unit that causes the
A communication system equipped with Each of the one or more relay stations performs filtering to suppress interference between the signal received from the transmitting station and the signal transmitted to the receiving station, which occurs in each of the one or more relay stations. Equipped with 1 filter,
The first filter is
giving the first delay time to the first signal by the filtering;
giving the first phase rotation amount to the first signal after the filtering;
The communication system according to claim 1. The control unit includes:
The relay signal of the first signal is transmitted to the first relay station after a second time length obtained by subtracting the propagation delay between the first relay station and the receiving station from the first time length from the beginning of the slot. obtaining the first delay time so as to be transmitted from the relay station;
The communication system according to claim 1 or 2. Each of the one or more relay stations includes:
comprising an antenna, a transmitter and a receiver connected to the antenna,
The control unit includes:
From the amount of phase rotation applied at the receiver, the amount of phase rotation applied at the transmitter, the amount of phase rotation applied in the propagation path from the transmitting station to the first relay station, and the amount of phase rotation applied from the first relay station to the reception obtaining the value obtained by subtracting the amount of phase rotation added in the propagation path to the station as the first amount of phase rotation;
The communication system according to claim 1 or 2. The control unit includes:
Based on the propagation delay between the first relay station and the receiving station, the relay signal of the first signal transmitted from the first relay station is transmitted to the receiving station from the beginning of the slot to the first relay signal. Determine whether it is possible to arrive by the time after,
When it is determined that the relay signal of the first signal from the first relay station can arrive at the receiving station by a first time after the beginning of the slot, the first relay station determining whether to relay the first signal;
If it is determined that the relay signal of the first signal from the first relay station cannot arrive at the receiving station by a first time after the beginning of the slot, the first relay station determining whether to relay the first signal;
The communication system according to claim 1. The control unit includes:
a propagation delay between the transmitting station and the first relay station, a delay spread between the transmitting station and the first relay station, a processing delay at the first relay station, and the first relay station. of the first signal from the first relay station by determining whether the total time of the propagation delay between the relay station and the receiving station is less than or equal to the first time length. determining whether the relay signal arrives at the receiving station by a first time after the beginning of the slot;
The communication system according to claim 5. It is further equipped with a control device that manages the wireless line,
The control device includes:
Obtaining the first time length based on radio wave propagation characteristics between the transmitting station and the receiving station and radio wave propagation characteristics between each of the one or more relay stations and the receiving station;
Notifying the first time length to the one or more relay stations;
The communication system according to claim 1, wherein the communication system performs the following. The control device includes:
a propagation delay between the transmitting station and the receiving station, a delay spread between the transmitting station and the receiving station, and a delay time caused by relaying by one of the one or more relay stations. and, by summing the above, the first time length is obtained.
The communication system according to claim 7. The computer is
A relay signal of one or more of the first signals relayed by one or more relay stations that relays the first signal from the transmitting station to the receiving station without demodulating or decoding is transmitted to the transmitting station and the receiving station. and the one or more relay stations, such that the first signal arrives at the receiving station at the same time and in phase a first time length from the beginning of the slot in the transmitted radio frame. and, regarding at least a first relay station of the one or more relay stations, radio wave propagation characteristics between the transmitting station and the first relay station and between the receiving station and the first relay station. obtain a first delay time and a first amount of phase rotation given to the first signal by relaying by the first relay station, based on radio wave propagation characteristics;
causing the first relay station to give the first delay time and the first amount of phase rotation to the first signal;
Method. In the case of non-regenerative relay in which a first signal from a transmitting station to a receiving station is relayed without demodulating or decoding, the relay signal of the first signal is transmitted to the transmitting station, the receiving station, and one or more relay stations. radio wave propagation between the receiving station and the receiving station such that the first signal arrives at the receiving station after a first length of time from the beginning of the slot in the radio frame in which the first signal is transmitted; obtaining a first delay time based on the characteristic;
obtaining a first phase rotation amount that cancels the phase rotation amount added to the first signal by the relay;
a control unit that executes
a wireless processing unit that provides the first delay time and the first phase rotation amount to the first signal during the non-regenerative relay of the first signal;
A relay station equipped with The wireless processing unit includes a first filter that performs filtering to suppress interference between the signal received from the transmitting station and the signal transmitted to the receiving station, which occurs in the wireless processing unit,
The first filter is
giving the first delay time to the first signal by the filtering;
giving the first phase rotation amount to the first signal after the filtering;
The relay station according to claim 10. The control unit includes:
A relay signal of the first signal is transmitted from the wireless processing unit after a second time length obtained by subtracting a propagation delay between the relay station and the receiving station from the first time length from the beginning of the slot. obtaining the first delay time so that
The relay station according to claim 10 or 11. The wireless processing unit includes a transmitter and a receiver connected to an antenna,
The control unit includes:
From the amount of phase rotation applied at the receiver, the amount of phase rotation applied at the transmitter, the amount of phase rotation applied on the propagation path from the transmitting station to the relay station, and the amount of phase rotation applied on the propagation path from the relay station to the receiving station. obtaining the value obtained by subtracting the amount of phase rotation to be applied as the first amount of phase rotation;
The relay station according to claim 10 or 11. The control unit includes:
Based on the propagation delay between the relay station and the receiving station, the relay signal of the first signal transmitted from the radio processing unit is transmitted to the receiving station by a first time after the beginning of the slot. Determine whether it is possible to arrive,
determining that the first signal is to be relayed if it is determined that the relay signal of the first signal can arrive at the receiving station by a first time after the beginning of the slot;
If it is determined that the relay signal of the first signal cannot arrive at the receiving station by a first time after the beginning of the slot, it is determined that the relay signal of the first signal is not to be relayed. ,
The relay station according to claim 10. The control unit includes:
a propagation delay between the transmitting station and the relay station, a delay spread between the transmitting station and the relay station, a processing delay in the radio processing section, and a delay between the relay station and the receiving station. By determining whether the total time of the propagation delay and is less than or equal to the first time length, the relay signal of the first signal is transmitted to the receiving station from the beginning of the slot until after the first time. determine whether or not the
The relay station according to claim 14. The control unit includes:
The first time length obtained based on the radio wave propagation characteristics between the transmitting station and the receiving station and the radio wave propagation characteristics between each of the one or more relay stations and the receiving station, received from a control device that manages the
The relay station according to claim 10. The first time length is
a propagation delay between the transmitting station and the receiving station, a delay spread between the transmitting station and the receiving station, and a delay time caused by relaying by one of the one or more relay stations. is obtained by summing and,
The relay station according to claim 16. One or more relay stations that relay a first signal from a transmitting station to a receiving station without demodulating or decoding the first signal, the relaying signal of the first signal is transmitted between the transmitting station, the receiving station, and the one or more stations. The first signal, which is synchronized with the relay station, arrives at the receiving station at the same time and in phase after a first time length from the beginning of the slot in the transmitted radio frame. When giving a first delay time and a first amount of phase rotation to a signal of obtaining the first time length based on the radio wave propagation characteristics;
a control unit that executes
A control device comprising: The control unit includes:
a propagation delay between the transmitting station and the receiving station, a delay spread between the transmitting station and the receiving station, and a delay time caused by relaying by one of the one or more relay stations. and, by summing the above, the first time length is obtained.
The control device according to claim 18. The control unit includes:
Regarding at least a first relay station of the one or more relay stations, radio wave propagation characteristics between the transmitting station and the first relay station and radio waves between the receiving station and the first relay station. obtaining a first delay time and a first phase rotation amount given to the first signal by relaying by the first relay station based on propagation characteristics;
Notifying the first relay station of the first delay time and the first phase rotation amount;
The control device according to claim 18 or 19.

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