WO2025134230A1 - Wireless communication system, receiving station, wireless communication method, and program for wireless communication - Google Patents

Abstract

The purpose of the present disclosure is to provide a wireless communication system that can collectively apply MIMO signal processing to reception signals received by a plurality of reception antennas. A wireless communication system according to the present disclosure is provided with a transmitting station, and a receiving station that performs MIMO wireless communication with the transmitting station. The receiving station includes a plurality of reception antennas, one or more synthesis circuits, a synchronization/equalization circuit, and a demodulation circuit. The synthesis circuit synthesizes reception signals of some of the plurality of reception antennas so that synthesized signals equal to or greater than the number of transmission antennas of the transmitting station remain. The synchronization/equalization circuit applies timing synchronization to the synthesized signals, and equalizes the signals in terms of time and frequency domain. The demodulation circuit demodulates the equalized synthesized signals.

Description

Wireless communication system, receiving station, wireless communication method, and wireless communication program

This disclosure relates to a wireless communication system, a receiving station, a wireless communication method, and a program for wireless communication.

Non-Terrestrial Networks (NTNs) are expected to have many use cases, such as direct accommodation of terrestrial terminals, mobile backhaul, and accommodation of IoT terminals, and are expected to generate more traffic than existing satellite communications (e.g., Non-Patent Document 1). To increase the capacity of the lines, a technology has been disclosed that performs MIMO (Multiple-Input and Multiple-Output) wireless communications between multiple antennas installed at an overhead radio station and multiple antennas installed at a terrestrial base station (e.g., Non-Patent Document 2). Alternatively, a method has been proposed for constructing Massive MIMO by arranging a large number of small antennas over a wide area at terrestrial base stations (e.g., Non-Patent Document 3).

Non-Patent Document 4 discloses a technique for inserting dummy frames into radio frames and using the dummy frames to perform timing synchronization and channel estimation for the signals received at each receiving antenna. This makes it possible to perform MIMO signal processing while maintaining frequency utilization efficiency.

3GPP TR 38.821, 3rd Generation Partnership Project; Technical Specification Group Radio Access Network; Solutions for NR to Support Non-Terrestrial Networks (NTN) (Release 16), V16.1.0, May 2021. A. Knopp, R. T. Schwarz, D. Ogermann, C. A. Hofmann and B. Lankl, "Satellite System Design Examples for Maximum MIMO Sp ectral Efficiency in LOS Channels," IEEE GLOBECOM 2008 - 2008 IEEE Global Telecommunications Conference, 2008, pp. 1-6. Tategami et al., "Proposal of a hierarchical base station configuration for ultra-wideband Massive MIMO systems," Proceedings of the IEICE General Conference, Communications Lecture Series 1, B-3-5, Mar 2023. Goto et al., "Frame Efficiency Evaluation of LEO-MIMO for DVB-S2X Transmission," IEICE General Conference, Communications Lecture Proceedings 1, B-3-4, Mar 2023.

However, the technique of Non-Patent Document 4 requires that MIMO signal processing such as timing synchronization, channel estimation, and equalization be performed individually on signals received at multiple receiving antennas, which imposes a large processing burden.

In order to solve the above-mentioned problems, the first objective of this disclosure is to provide a wireless communication system that can perform MIMO signal processing collectively on signals received at multiple receiving antennas.

A second object of this disclosure is to provide a receiving station that can collectively perform MIMO signal processing on signals received at multiple receiving antennas.

A third object of this disclosure is to provide a wireless communication method that can collectively perform MIMO signal processing on signals received at multiple receiving antennas.

A fourth object of the present disclosure is to provide a wireless communication program that can collectively perform MIMO signal processing on signals received at multiple receiving antennas.

The first aspect of the present disclosure is
A transmitting station;
a receiving station that performs MIMO wireless communication with the transmitting station,
The receiving station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
having
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
Preferably, the demodulation circuit is adapted to perform a process for demodulating the equalized composite signal in a wireless communication system.

The second aspect is
A receiving station that performs MIMO wireless communication with a transmitting station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
Equipped with
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
The demodulation circuitry is preferably a receiving station arranged to perform a process for demodulating the equalised composite signal.

The third aspect is
A receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domains;
demodulating the equalized composite signal;
It is desirable to provide a wireless communication method comprising:

The fourth aspect is
A wireless communication program to be executed by a receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
The receiving station,
a process of combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domain;
demodulating the equalized composite signal;
It is preferable that the wireless communication program includes a program for executing the above.

According to the present disclosure, signals received at multiple receiving antennas are combined using a combining circuit. The combined signal can be considered as a pseudo multipath signal, and time-frequency domain equalization can be applied. Therefore, it is possible to provide a wireless communication system, a receiving station, a wireless communication method, and a wireless communication program that can collectively perform MIMO signal processing on signals received at multiple receiving antennas.

1 is a diagram illustrating a configuration example of a wireless communication system according to a first embodiment of the present disclosure. FIG. 2 is a block diagram of a transmitting station according to the first embodiment of the present disclosure. FIG. 2 is a block diagram of a receiving station according to the first embodiment of the present disclosure. 4 is a flowchart of a process executed by a transmitting station and a receiving station according to the first embodiment of the present disclosure. FIG. 11 is a diagram illustrating a configuration example of a wireless communication system according to a modified example of the first embodiment of the present disclosure. 13 illustrates a frame format of an information signal transmitted by a transmitting station according to a second embodiment of the present disclosure. FIG. 11 is a block diagram of a transmitting station according to a second embodiment of the present disclosure. 11 is a diagram for explaining a CP length calculation method performed by a CP length calculation circuit according to a second embodiment of the present disclosure. FIG.

The embodiments of the present disclosure will be described with reference to the drawings. The same or corresponding components will be given the same reference numerals, and repeated explanations may be omitted.

First embodiment
1 is a diagram showing a configuration example of a wireless communication system 100 according to a first embodiment of the present disclosure. The wireless communication system 100 includes a transmitting station 110 and a receiving station 120. The transmitting station 110 has two transmitting antennas (hereinafter, antennas) 111-1 and 111-2. The receiving station 120 has multiple receiving antennas (hereinafter, antennas) 121-1, 121-2, and so on.

In the following, the description applies to each of antenna 111-1, antenna 111-2, etc., and when there is no need to distinguish between them, they will simply be referred to as antenna 111. The same applies to antenna 121-1, antenna 121-2, etc., and lines 10-1, 10-2, etc., lines 20-1, 20-2, etc., described below.

The multiple antennas 111 of the transmitting station 110 are connected to each of the multiple antennas 121 of the receiving station 120 via line 10 or line 20, and perform MIMO wireless communication using spatial multiplexing. Specifically, antenna 111-1 connects antenna 121-1, antenna 121-2, etc. to lines 10-1, 10-2, etc., respectively. Similarly, antenna 111-2 connects antenna 121-1, antenna 121-2, etc. to lines 20-1, 20-2, etc., respectively.

The transmitting station 110 generates information signals s ₁ , s ₂ , ... directed to each of the antennas 111-1, 111-2, ... and distributes them to the target antennas 111. The antenna 111 transmits the received information signals to the receiving station 120 via the multiple lines 10 or lines 20 connected to it. The receiving station 120 receives the information signals s ₁ , s ₂ , ... originating from each of the antennas 111-1, 111-2, ... at each antenna 121.

Note that, although the case where the transmitting station 110 has two antennas 111 has been described here, the number of antennas 111 is not limited and may be any number equal to or greater than the number of information signals to be transmitted. Therefore, if there is one information signal to be transmitted, one antenna 111 may be sufficient.

2 is a block diagram of the transmitting station 110 according to the first embodiment of the present disclosure. The transmission signal generating circuit 112 performs signal processing such as S/P (Serial to Parallel) conversion, error correction coding, and modulation on the information signals s ₁ , s ₂ , ... to be transmitted. The modulation method adopted is a method capable of equalization in the time and frequency domains in the receiving station 120, such as OFDM, spectrum spread, and DFTs (Discrete Fourier Transform-spread)-OFDM. The transmission signal generating circuit 112 distributes the generated information signals s ₁ , s ₂ , ... to the target antennas 111.

FIG. 3 is a block diagram of a receiving station 120 according to the first embodiment of the present disclosure. Each antenna 121 guides radio waves that reach it and converts them into power signals. The power signals at each antenna 121 are converted into optical signals by an EO (Electro-Optical) converter 122 that is unique to each antenna 121, and are transmitted to a receiver 123 via optical fiber. The receiver 123 converts the received optical signal back into an electric power signal. In this way, the radio waves that reach the antenna 121 are received. Hereinafter, the radio waves converted into electric power signals by the receiver 123 that is unique to each antenna 121 will be referred to as the received signals at each antenna 121.

Here, we have explained that the power signal at each antenna 121 is converted into an optical signal using optical fiber radio technology before being transmitted to the receiver 123. The use of optical fiber can reduce transmission loss, which is particularly useful when the distance from the antenna 121 to the receiver 123 is long. However, the power signal at each antenna 121 does not necessarily have to be converted into an optical signal, and may be transmitted to the receiver 123 using a coaxial cable or the like.

The signals received by each antenna 121 are transmitted to a synthesis circuit 124, which is connected to a specific destination for each antenna 121. Each of the multiple synthesis circuits 124 synthesizes some of the received signals from the multiple antennas 121 to generate a synthetic signal.

For example, the combining circuit 124-1 combines the received signals for a first combination of antennas 121-1, 121-3, and 121-5. The combining circuit 124-2 combines the received signals for a second combination of antennas 121-2, 121-4, and 121-6.

Here, assuming that the number of combining circuits 124 is N _min and the number of antennas 111 of the transmitting station 110 is N, N _min ≧N. This is because in order for the demodulation circuit 126 described later to separate each of the multiple information signals s ₁ , s ₂ , ... contained in the combined signal, a combined signal equal to or greater than the number of information signals to be separated is required. Therefore, if the transmitting station 110 has one antenna 111, one combining circuit 124 may be sufficient.

The synchronization/equalization circuit 125 performs timing synchronization on the combined signal received from the combining circuits 124 connected thereto, and performs equalization in the time and frequency domains. The demodulation circuit 126 receives the combined signal from each of the synchronization/equalization circuits 125, performs channel estimation on the combined signal, and separates the multiple information signals s ₁ , s ₂ , ... contained in the combined signal. The demodulation circuit 126 further demodulates the combined signal.

If there is only one information signal to be separated, the demodulation circuit 126 does not separate the composite signal.

In this manner, in this disclosure, MIMO signal processing such as timing synchronization, channel estimation, and equalization is performed on the composite signal generated in each composite circuit 124.

Next, a description will be given of the combined signal generated in the combining circuit 124. Here, a case will be described in which information signals s ₁ and s ₂ are transmitted from the antennas 111-1 and 111-2 of the transmitting station 110, respectively, and the information signals s ₁ and s ₂ are received by the six antennas 121 of the receiving station 120.

First, the power r _k of the received signal at the kth antenna 121-k can be written as follows:

Here, t is time, and τ _k is a time offset that differs for each antenna 121. Furthermore, s ₁ (t) and s ₂ (t) indicate the powers of information signals s ₁ and s ₂ at time t.

Here, the combining circuit 124 combines the received signals from each antenna 121 without timing synchronization. In this case, in the combining circuit 124-1 that combines the received signals for the first combination of antennas 121-1, 121-3, and 121-5, the power of the combined signal is as follows:

It should be noted that since timing synchronization is not performed on the received signals at each antenna 121, in equation (2), information signals s ₁ and s ₂ are added together with a time offset τ _k .

Similarly, in the combining circuit 124-2 that combines the received signals for the second combination of antennas 121-2, 121-4, and 121-6, the power of the combined signal is as follows:

Here, the first term on the right side of (Equation 2) is the sum of the received power of the information signal s ₁ at each antenna 121 included in the first combination. The first term can be considered as a state in which the information signal s ₁ originating from each antenna 121 interferes in the time domain. The second term can also be considered as a state in which the information signal s ₂ originating from each antenna 121 interferes in the time domain. Therefore, the composite signal r ₁ ^sum expressed in this way can be considered as a pseudo multipath signal. The same applies to the composite signal r ₂ ^sum of (Equation 3).

Based on the knowledge that time-frequency domain equalization used in OFDM or spectrum spread, etc., can be applied to a composite signal having such characteristics, this disclosure applies time-frequency domain equalization processing to the composite signal.

The synchronization process here means removing the offset time τ _k in each antenna 121 from the composite signal r ₁ ^sum expressed by (Equation 2) or matching the offset time τ _k in each antenna 121. This also applies to the composite signal r ₂ ^sum expressed by (Equation 3).

4 is a flowchart of a process executed by the transmitting station 110 and the receiving station 120 according to the first embodiment of the present disclosure. First, the transmission signal generating circuit 112 of the transmitting station 110 generates information signals _s1 , _s2 , ... and distributes them to the target antenna 111 (step S01). Next, the antenna 111 transmits the received information signal to the receiving station 120 via the line 10 or line 20 connected to the transmitting station 110 (step S02).

Furthermore, the receivers 123 connected to each antenna 121 of the receiving station 120 receive the information signal (step S03). Each of the combining circuits 124 combines some of the received signals from the multiple antennas 121 to generate a combined signal (step S04). Next, the synchronization/equalization circuit 125 performs timing synchronization on the combined signal received from the combining circuit 124 connected to itself, and further performs equalization in the time and frequency domains (step S05). Furthermore, the demodulation circuit 126 separates and demodulates each of the multiple information signals s ₁ , s ₂ , ... included in the combined signal (step S06). Finally, the process ends.

As described above, according to the present disclosure, received signals at multiple antennas 121 are combined by a combining circuit 124. The combined signal can be considered as a pseudo multipath signal, and time-frequency domain equalization can be applied. Therefore, it is possible to provide a wireless communication system, a receiving station, a wireless communication method, and a wireless communication program that can collectively perform MIMO signal processing on received signals received at multiple receiving antennas.

The wireless communication system 100 disclosed herein also exhibits the above-mentioned effects when applied to an NTN system. For example, the transmitting station 110 is an airborne wireless station such as a satellite that moves in the sky, including outer space, and the receiving station 120 is a terrestrial base station. Furthermore, the lines 10 and 20 are feeder link lines.

<Modification of the First Embodiment>
5 is a diagram showing a configuration example of a wireless communication system 100 according to a modification of the first embodiment of the present disclosure. The wireless communication system 100 includes a transmitting station 110 as a terrestrial base station, and a receiving station 120 connected to a plurality of satellites 130. In this example, three satellites 130-1, 130-2, and 130-3 are arranged in a distributed manner with respect to the receiving station 120. Distributing the satellites 130 in this manner is known from LEO (Low Earth Orbit) satellite constellations and the like.

Antennas 121 of the receiving station 120 are arranged on each satellite 130. The received signals received by each antenna 121 are transmitted via optical link 30 to a combining circuit 124, the connection destination of which is determined for each antenna 121. Each of the two combining circuits 124 combines the received signals for the combination of antennas 121 selected one by one from each satellite 130. Furthermore, the above-mentioned MIMO signal processing is carried out in the downstream synchronization/equalization circuit 125 and demodulation circuit 126. This makes it possible to obtain the same effects as in embodiment 1.

The combining circuit 124, synchronization/equalization circuit 125, and demodulation circuit 126 may be located in any one of the satellites 130. In that case, however, it is necessary to connect the multiple satellites 130 with optical links 30 and transmit the received signal at each antenna 121 to the satellite 130 in which the circuits are located.

Embodiment 2
In this embodiment, a frame of an information signal includes a preamble 51 for timing synchronization and a pilot symbol 53. The following describes changes from the first embodiment.

FIG. 6 shows the frame format of an information signal transmitted by a transmitting station 110 according to the second embodiment of the present disclosure. The information signal has a frame format similar to that of a burst frame used in wireless LANs (Local Area Networks) and LTE (Long Term Evolution). That is, the information signal includes a preamble 51, a data symbol 52, and a pilot symbol 53 in one frame. The symbol here is, for example, an OFDM symbol. The number of preambles 51, the number of data symbols 52, the number of pilot symbols 53, and the spacing between pilot symbols 53 in one frame are not limited.

Note that a guard interval (Cyclic Prefix, CP) is inserted at the beginning of each symbol.

FIG. 7 is a block diagram of a transmitting station 110 according to a second embodiment of the present disclosure. A CP length calculation circuit 113 calculates the CP length to be provided in the frame of the information signal to be transmitted based on the position information of the transmitting station and the receiving station 120, using a method to be described later. A position information acquisition circuit 114 acquires the position information of the transmitting station and the receiving station 120 using GPS or the like. In addition to the processing described in the first embodiment, the transmission signal generation circuit 112 further executes processing to provide the CP length calculated by the CP length calculation circuit 113 for the symbols of the information signal to be transmitted.

Meanwhile, in the receiving station 120, the synchronization and equalization circuit 125 performs timing synchronization based on the preamble 51 included in the information signal. Furthermore, the demodulation circuit 126 performs channel estimation based on the pilot symbol 53 included in the information signal.

In this way, by including a preamble 51 for synchronization and a pilot symbol 53 for channel estimation in the frame of the information signal, the time required for MIMO signal processing in the receiving station 120 can be shortened. Therefore, this is particularly useful in cases where MIMO signal processing must be performed in a short time, such as when at least one of the transmitting station 110 and the receiving station 120 is a mobile station.

In the above, it has been explained that the information signal is a burst frame transmitted at regular intervals. However, in cases where the transmitting station 110 that is the source of the information signal is not a mobile station, or where it appears to be stationary relative to the ground, such as a geostationary satellite, the information signal may be a continuous frame.

In the above, it has been explained that the symbols are OFDM symbols, but any method that allows equalization in the time and frequency domains may be used, and symbols in a single-carrier method such as DFTs-OFDM or SC-FDE (Single-Carrier Modulation with Frequency Domain Equalization) may also be used.

8 is a diagram for explaining a CP length calculation method performed by the CP length calculation circuit 113 according to the second embodiment of the present disclosure. The CP length calculation circuit 113 (not shown) calculates the line lengths of the lines 10 and 20 that connect the local station to the receiving station 120 based on the position information of the local station and the receiving station 120. Here, it is assumed that the line length of the line 10-N that connects the antenna 111-1 and the antenna 121-N of the lines 10 and 20 is the maximum D _max among all the lines 10 and 20. It is also assumed that the line length of the line 10-1 that connects the antenna 111-1 and the antenna 121-1 is the minimum D _min among all the lines 10 and 20.

The CP length calculation circuit 113 calculates the arrival time difference Δ of the information signal between the antenna 121-N which is responsible for the line 10-N having the longest line length and the antenna 121-1 which is responsible for the line 10-1 having the shortest line length. The arrival time difference Δ can be obtained as ((D _max -D _min )/c) using the line length difference and the speed of light c. The CP length calculation circuit 113 determines the CP length so as not to exceed the calculated arrival time difference Δ. This makes it possible to keep the delay time, which is the difference between the information signal which arrives at the receiving station 120 the fastest and the information signal which arrives at the receiving station 120 the slowest, within the CP length, and equalization of the composite signal is normally performed in the receiving station 120.

If the distance from antenna 121 to receiver 123 is long, the line length from each antenna 121 to receiver 123 may be taken into consideration in addition to the line length of lines 10 and 20.

The processes performed by the synthesis circuit 124, synchronization/equalization circuit 125, and demodulation circuit 126 of the receiving station 120 and the processes performed by the CP length calculation circuit 113 of the transmitting station 110 may be executed by a program using a computer equipped with a CPU and memory and having a program stored in the memory. Alternatively, the processes may be executed by a program using an integrated circuit such as an FPGA (Field Programmable Gate Array). The programs may be provided by being recorded on a storage medium, or may be provided via a network. This point is common to all the embodiments.

Note that this disclosure is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the disclosure. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained.

Various aspects of the present disclosure are summarized below as appendices.
(Appendix 1)
A transmitting station;
a receiving station that performs MIMO wireless communication with the transmitting station,
The receiving station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
having
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
The demodulation circuit is configured to perform a process for demodulating the equalized composite signal.
(Appendix 2)
The transmitting station,
A process of calculating a line length between a transmitting antenna of the local station and the receiving antenna based on position information of the local station and the receiving station;
A process of calculating an arrival time difference of the information signal at the receiving antenna serving the line with the longest line length and the receiving antenna serving the line with the shortest line length;
a process of adding a cyclic prefix length not exceeding the arrival time difference to a symbol of the information signal to be transmitted and then transmitting the information signal via the line;
2. The wireless communication system of claim 1, further configured to:
(Appendix 3)
A receiving station that performs MIMO wireless communication with a transmitting station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
Equipped with
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
The demodulation circuitry of the receiving station is configured to perform a process for demodulating the equalized composite signal.
(Appendix 4)
A receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domains;
demodulating the equalized composite signal;
A wireless communication method comprising:
(Appendix 5)
A wireless communication program to be executed by a receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
The receiving station,
a process of combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domain;
demodulating the equalized composite signal;
A program for wireless communication, comprising a program for executing the above.

10, 20 Line, 30 Optical link, 51 Preamble, 52 Data symbol, 53 Pilot symbol, 100 Wireless communication system, 110 Transmitting station, 111 Transmitting antenna, 112 Transmitting signal generating circuit, 113 CP length calculation circuit, 114 Position information acquisition circuit, 120 Receiving station, 121 Receiving antenna, 122 EO converter, 123 Receiver, 124 Combining circuit, 125 Synchronization and equalization circuit, 126 Demodulation circuit, 130 Satellite

Claims (4)

A transmitting station;
a receiving station that performs MIMO wireless communication with the transmitting station,
The receiving station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
having
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
The demodulation circuit is configured to perform a process for demodulating the equalized composite signal. A receiving station that performs MIMO wireless communication with a transmitting station,
A plurality of receiving antennas;
one or more combining circuits that combine some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
A synchronization and equalization circuit;
A demodulation circuit;
Equipped with
the synchronization and equalization circuit is configured to perform timing synchronization and equalization in the time and frequency domains on the composite signal;
The demodulation circuitry of the receiving station is configured to perform a process for demodulating the equalized composite signal. A receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domains;
demodulating the equalized composite signal;
A wireless communication method comprising: A wireless communication program to be executed by a receiving station that performs MIMO wireless communication with a transmitting station using a plurality of receiving antennas,
The receiving station,
a process of combining some of the received signals from the plurality of receiving antennas so that the number of combined signals remaining is equal to or greater than the number of transmitting antennas of the transmitting station;
applying timing synchronization to the composite signal and equalizing it in the time and frequency domain;
demodulating the equalized composite signal;
A program for wireless communication, comprising a program for executing the above.

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