JP7640410B2 - COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM - Google Patents

Description

The present invention relates to a communication device, a communication method, and a program for receiving wireless signals using multiple antennas that are distributed.

When radio signals are transmitted from transmission points such as geographically dispersed user terminals to multiple receiving antennas concentrated in one location, differences in propagation delays occur due to the propagation environment (links) between each antenna, and the signals are received as asynchronous signals at the receiving antennas. For this reason, user separation is performed to eliminate the differences in propagation delays of the radio signals from the user terminals using a space-time filter. In addition, because differences occur in the frequencies of the radio signals transmitted from each user terminal, the frequency offset is compensated for when demodulating and decoding on the receiving side.

Non-Patent Document 1 discloses the design of a space-time filter, in which the first OFDM symbol in a specific reception processing period (e.g., the first slot) is used as a training symbol to estimate the propagation delay difference and frequency offset of each link. The coefficients (weights) of the space-time filter are set based on these estimates, and the propagation delay difference is absorbed by superimposing the weights on the signals received in the specific reception processing period, and the received signals are separated into streams for each user. After that, the frequency offset is compensated for for each user stream, and OFDM demodulation is performed.

T. Tang and R. W. Heath, "A Space-Time Receiver With Joint Synchronization and Interference Cancellation in Asynchronous MIMO-OFDM Systems," in IEEE Transactions on Vehicular Technology, vol. 57, no. 5, pp. 2991-3005, Sept. 2008

However, Non-Patent Document 1 assumes an environment in which receiving antennas are concentrated in one location, and therefore assumes that no frequency offset occurs between the receiving antennas used when demodulating and decoding on the receiving side. However, in an environment in which receiving antennas are distributed, frequency conversion of radio signals to baseband signals may be performed by different wireless communication circuits for each receiving antenna. In such cases, frequency offsets may occur between multiple wireless communication circuits, causing a shift in the frequency of the baseband signal after frequency conversion, resulting in a problem of reduced reception performance.

The present invention was made in consideration of the above-mentioned problems, and aims to prevent a decrease in the reception performance of a communication device that receives wireless signals due to a frequency offset between multiple wireless circuits.

In order to achieve the above object, a communication device according to one aspect of the present invention is a communication device for receiving, via a plurality of antennas, a radio signal including a signal transmitted from a first transmitting device and a signal transmitted from a second transmitting device different from the first transmitting device ,
acquiring a first reception signal obtained by frequency-converting the radio signal from a first radio circuit connected to a first antenna of the plurality of antennas;
acquiring a second reception signal obtained by frequency-converting the radio signal from a second radio circuit connected to a second antenna of the plurality of antennas;
A signal acquisition unit;
an output unit that receives the first and second received signals acquired by the signal acquisition unit as input and generates a plurality of output signals for each transmitting device;
a frequency offset compensation unit for compensating for a frequency offset for each of the plurality of output signals based on the first and second received signals;
The present invention is characterized by comprising:

The present invention makes it possible to prevent degradation of reception performance due to frequency offsets between multiple receiving antennas.

FIG. 1 is a diagram showing a communication system including a communication device according to an embodiment of the present invention. FIG. 1 is a configuration diagram of a communication device according to a first embodiment. FIG. 11 is a configuration diagram of a communication device according to a second embodiment. FIG. 13 is a configuration diagram of a communication device according to a third embodiment. 5 is a flowchart showing an example of a process executed by the communication device according to the embodiment.

The following embodiments are described in detail with reference to the attached drawings. Note that the following embodiments do not limit the invention according to the claims. Although the embodiments describe multiple features, not all of these multiple features are necessarily essential to the invention, and multiple features may be combined in any manner. Furthermore, in the attached drawings, the same reference numbers are used for the same or similar configurations, and duplicate explanations are omitted.

First Embodiment
FIG. 1 shows an example of the configuration of a wireless communication system according to this embodiment. In one example, the wireless communication system 1 is a 5G cellular communication system (mobile communication network). However, the present system is not limited to this, and may be, for example, a successor cellular communication system after 5G, or may be a wireless communication system other than a cellular system. The present system includes a receiving device (communication device) 10 and transmitting devices 20A to 20C (hereinafter, sometimes referred to as a transmitting device 20 without distinction). Note that, in FIG. 1, three transmitting devices and one receiving device are shown for the sake of simplicity of explanation, but the number of these devices is not limited, and more transmitting devices and receiving devices may naturally exist.

The receiving device 10 according to this embodiment has antennas that are geographically distributed. For example, the antennas of the receiving device 10 may be realized by an access point or a cellular base station, and the signal processing unit described below may be a central processing unit (CPU). In this case, the antennas and the signal processing unit may be connected by a backbone network. In one example, the transmitting device 20 is a user terminal device.

Next, the configuration of the receiving device 10 will be described with reference to FIG. 2.

The receiving device 10 includes a plurality of antennas 101 ₁ to 101 _n (hereinafter, they may be simply referred to as antennas 101).

Each antenna 101 is connected to radio circuits 102 ₁ to 102 _n (hereinafter sometimes referred to simply as radio circuits 102) that include local oscillators (LO) 121 ₁ to 121 _n (hereinafter sometimes referred to simply as LOs 121). The radio circuits 102 frequency-convert the radio signals received from the antennas 101 to baseband signals and transmit the signals to the signal processing unit 103. Note that although only the LO 121 and a mixer are illustrated in FIG. 2, the radio circuit 102 includes additional high-frequency elements such as an amplifier and a high-frequency filter.

The signal processing unit 103 includes a signal acquisition unit 130, space-time filter units 131 ₁ to 131 _m (hereinafter sometimes referred to as space-time filter units 131 without distinction), frequency offset (FO) compensation units 132 ₁ to 132 _m (hereinafter sometimes referred to as frequency offset compensation units 132 without distinction), cyclic prefix (CP) removal units 133 ₁ to 133 _m (hereinafter sometimes referred to as CP removal units 133 without distinction), and frequency domain equalization units 134 ₁ to 134 _m (hereinafter sometimes referred to as frequency domain equalization units 134 without distinction).

The signal acquisition unit 130 receives a baseband signal from the antenna 101. In one example, the signal acquisition unit 130 may acquire parameters of the radio circuit 102, such as the power of the received signal and the frequency of the LO 121. The baseband signal acquired by the signal acquisition unit 130 is input to the space-time filter unit 131, and is also input to the space-time filter control unit 141, the frequency offset (FO) determination unit 142, and the equalization control unit 143, and is used to determine the control parameters.

The space-time filter unit 131 is an output unit that inputs baseband signals acquired from multiple radio circuits 102 in the order in which they were sampled, and outputs an output signal (user stream) in which the baseband signals are separated into users for each transmitting device 20.

The CP removal unit 133 detects the symbol timing, removes the CP by removing a predetermined number of samples from the beginning of the symbol, and then converts the time-series baseband signal into frequency-series signal data using a discrete Fourier transform (DFT).

The frequency domain equalization unit 134 equalizes the signal data in the frequency domain based on the signal strength of the pilot frequency included in the signal data by the transmitting device 20.

The CP removal unit 133 and the frequency domain equalization unit 134 can use the publicly known technology described in Non-Patent Document 1, so a detailed description is omitted.

The signal processing unit 103 also includes a control unit 104. The control unit 104 includes a spatio-temporal filter control unit 141, an FO determination unit 142, and an equalization control unit 143.

The space-time filter control unit 141 determines the filter coefficients of the space-time filter unit 131 based on the training signals transmitted from each transmitting device 20, as described below.

The FO determination unit 142 identifies a frequency offset with respect to the transmitting device 20 based on the training signal transmitted from each transmitting device 20, and compensates for the frequency offset. The FO determination unit 142 according to this embodiment estimates the frequency offset for each antenna 101 based on the signal data of the training signal received by all antennas 101, and determines the amount of frequency offset compensated for by the FO compensation unit 132.

The equalization control unit 143 performs channel equalization by determining the signal strength for each subcarrier based on the training signal transmitted from each transmitting device 20.

（ｌ＝０～ν）とすると、送受信アンテナ間のチャネルを表すテプリッツ行列

を以下の数式１によって表現することができる。 (Space-time filter control unit)
Next, an example of control of the space-time filter control unit 141 will be described. In the case where there are M transmitting devices 20 that transmit signals to the receiving device 10 and the receiving device 10 has n antennas 101, the channel response between the m-th transmitting device 20 _m (1≦m≦M) and the j-th receiving antenna 101 _j (1≦j≦n) is expressed as follows:

(l = 0 to v), the Toeplitz matrix representing the channel between the transmitting and receiving antennas is

can be expressed by the following Equation 1.

とすると、以下の数式２が成り立つ場合に、所定の送信装置２０からの信号を強め、他の送信装置２０からの信号を弱めることができる。例えば、データストリームの順番を示すｉは、送信装置２０の識別子やトレーニング信号を送信した送信装置２０の順番に基づいて決定されてもよい。 In this case, the filter coefficients for user separation to extract the signal from the m-th transmitter 20 from the signal received at the j-th receiving antenna 101 _j are

Then, when the following formula 2 is satisfied, it is possible to strengthen the signal from a certain transmitting device 20 and weaken the signals from other transmitting devices 20. For example, i indicating the order of the data stream may be determined based on the identifier of the transmitting device 20 or the order of the transmitting devices 20 that transmitted the training signals.

は送信装置と受信装置との間の周波数オフセットであり、

は周波数オフセットによって発生する位相回転を表す直交行列であり、以下の数式３で表せる。 where

is the frequency offset between the transmitter and receiver,

is an orthogonal matrix representing a phase rotation caused by a frequency offset, and can be expressed by the following Equation 3.

を求めることで、複数の送信装置２０から送信された信号が、各送信装置２０に対応するデータストリームのうちの１つに出力され、他のデータストリームに出力されることを防ぐことができる。なお、フィルタ係数を求める計算処理については、例えば非特許文献１に記載の行列の計算を適用することで求めることができるため、詳細な説明は省略する。 Such filter coefficients

By obtaining , it is possible to prevent signals transmitted from a plurality of transmitting devices 20 from being output to one of the data streams corresponding to each transmitting device 20 and being output to the other data streams. Note that the calculation process for obtaining the filter coefficients can be performed by applying the matrix calculation described in Non-Patent Document 1, for example, and therefore a detailed description thereof will be omitted.

(FO Judgment Unit)
Next, a processing example of the FO determination unit 142 will be described. In Non-Patent Document 1, it is described that the radio circuits 102 of all the receiving antennas 101 operate at the same frequency. That is, in Non-Patent Document 1, it is conditioned that the multiple receiving antennas are aggregated in one place and the radio circuits 102 operate based on a signal supplied from one local oscillator. For this reason, the calculation has been simplified on the assumption that the operating frequencies of the multiple radio circuits are the same and Δ _i,j = Δ _i holds. In contrast, the receiving device 10 according to the present embodiment assumes that the multiple antennas 101 and the radio circuits 102 are distributed and therefore at least two radio circuits 102 operate with signals supplied from different local oscillators. For this reason, since the two radio circuits 102 may operate at different frequencies, Δ _i,j = Δ _i may not hold.

For this reason, the FO determination unit 142 according to this embodiment determines the frequency offset between the radio circuits 102 based on the baseband signals output from each of the radio circuits 102 that operate with signals supplied from different local oscillators 121. For example, even when the same radio signal is received, if the two radio circuits 102 operate with different clock frequencies, the frequencies of the baseband signals are different. For this reason, the frequency offset between the multiple radio circuits 102 can be determined by acquiring the baseband signals of the same radio signal from the multiple radio circuits 102 and determining the frequency offset between the baseband signals.

The FO determination unit 142 identifies the frequency offset Δ _i,j between the transmitting device 20 and each radio circuit 102 from the received signal. Here, a frequency offset exists for each combination of each transmitting device 20 and radio circuit 102, but the output from the space-time filter unit 131 contains a mixture of baseband signals output from multiple radio circuits 102. For this reason, if the frequency offset Δ _i,j of the radio circuit 102 is applied as is, there is a possibility that communication performance will be degraded. For this reason, the FO determination unit 142 according to this embodiment determines the frequency offset Δ _i in the data stream for each transmitting device 20, which is the output from the FO compensation unit 132, for each transmitting device 20, based on the multiple frequency offsets Δ _i ,j identified based on the outputs from the multiple radio circuits 102.

In one example, the FO determination unit 142 determines the frequency offset Δ i of the signal output as one data stream by the space-time filter unit 131 based on the frequency offset Δ _{i ,j} (j=0 to n) of each radio circuit 102 for the same training signal.

For example, the frequency offset Δ _i may be determined based on the following formula as the average value of each frequency offset: Alternatively, the received power P _i,j of the training signal may be specified, and the maximum value of P _i,j for the same training signal, i.e., for i' where i is the same, may be specified, and it may be determined that Δ _i,j = Δ _i,j' for j = 0 to n for j' where P _i ,j is maximum.

Furthermore, for example, the frequency offset Δi may be determined based on a weighted average in which each frequency offset Δ i, _j is weighted according to the received power P _i,j of the training signal, as shown in the following formula 5.

In this way, the receiving device according to this embodiment identifies the frequency offset between multiple radio circuits, and determines the amount of offset when performing FO compensation by the FO compensation unit based on the frequency offset between each of the multiple radio circuits. This makes it possible to perform frequency offset compensation for signals obtained by performing user separation of baseband signals obtained from radio circuits 102 operating with different local oscillators, and prevents degradation of reception performance due to frequency offsets between radio circuits.

Next, an example of the processing executed by the receiving device 10 according to this embodiment will be described with reference to FIG. 5. The processing shown in FIG. 5 is executed by the processor of the signal processing unit 103 executing a program stored in memory during the period in which the receiving device 10 transmits the training signal from the transmitting device 20.

In S501, the signal processing unit 103 acquires baseband signals obtained by frequency-converting training signals from multiple radio circuits 102. In one example, a parameter capable of identifying the received power, such as the gain of the amplifier of the radio circuit 102, may also be acquired. In addition, in S501, an identifier of the radio circuit 102, etc. may also be acquired.

Next, in S502, the signal processing unit 103 identifies the frequency offset between the radio circuits 102. The frequency offset between the radio circuits 102 may be determined by acquiring baseband signals for the same training signal from multiple radio circuits 102 and identifying the difference in frequency.

Next, in S503, the signal processing unit 103 determines the coefficients of a space-time filter for separating the data streams for each transmitting device 20 based on the multiple baseband signals acquired from the multiple radio circuits 102, as described above. Next, in S504, the FO determination unit 142 determines the offset amount (compensation value) to be set in the FO compensation unit 132. In one example, the FO determination unit 142 may determine the compensation value to be set in the FO compensation unit 132 based on the multiple baseband signals acquired from the multiple radio circuits 102 that have been frequency-converted from a training signal transmitted from one transmitting device 20.

Next, in S505, the equalization control unit 143 determines the equalization parameters to be set in the frequency domain equalization unit 134.

Through the above processing, the signal processing unit 103 can set the operating parameters of the space-time filter unit 131, the FO compensation unit 132, and the frequency domain equalization unit 134 based on the training signal.

Second Embodiment
Next, the configuration of a communication device according to the second embodiment will be described with reference to FIG.

The communication device 10 according to the second embodiment includes second FO compensation units 122 ₁ to 122 _n (hereinafter, sometimes referred to as second FO compensation units 122 without distinction) between the space-time filter unit 131 and the radio circuit, and a second FO determination unit 144. The second FO compensation unit 122 performs frequency offset compensation on a baseband signal obtained by frequency-converting a radio signal received by the antenna 101, in accordance with a compensation value set by the second FO determination unit 144 of the signal processing unit 103.

The first FO compensation unit 132 compensates for the frequency offset between the data streams for each transmitting device 20 after user separation, and the second FO compensation unit 122 compensates for the frequency offset between the radio circuits 102 before user separation.

The second FO determination unit 144, for example, determines the frequency offset between the multiple radio circuits 102 by comparing the frequencies of multiple baseband signals generated from a training signal from the same transmitting device 20 and acquired from the multiple radio circuits 102, and generates a compensation value for compensation.

The first FO determination unit 142 can determine and compensate for frequency offsets between multiple users (between multiple transmitting devices 20) by comparing the frequencies of multiple baseband signals obtained from the same radio circuit 102, for example, generated from training signals from multiple transmitting devices 20.

The coefficients of the time-space filter unit 131 are set based on the training signal after FO compensation by signal processing. This makes it possible to remove the frequency offset between the radio circuits 102 of the receiving device 10 and obtain diversity gain for receiving signals using multiple antennas 101.

As described above, the communication device according to this embodiment compensates for the frequency offset between multiple radio circuits on the receiving side before user separation by the space-time filter, and compensates for the frequency offset between multiple transmitting devices after user separation by the space-time filter. This makes it possible to treat the baseband signal as having no frequency offset after the space-time filter.

In FIG. 3, the signal processing unit 103 is shown as acquiring a baseband signal after the signal acquisition unit 130 compensates for the frequency offset between the radio circuits. However, the second FO compensation unit 122 may be disposed between the signal acquisition unit 130 and the space-time filter unit 131. In other words, the second FO compensation unit 122 may be disposed on the distributed antenna side or on the central processing unit side.

As described above, the communication device according to this embodiment compensates for the frequency offset between multiple radio circuits based on multiple baseband signals acquired from multiple radio circuits, and generates an output signal for each transmitting device by performing user separation from the baseband signals with the frequency offset compensated for. This makes it possible to apply known techniques to user separation and frequency offset compensation for each transmitting device.

Third Embodiment
Next, a third embodiment will be described with reference to Fig. 4. Note that a description of the same configuration as in the first and second embodiments will be omitted.

The communication device 10 according to this embodiment includes subunits 135 ₁ to 135 _n (hereinafter sometimes referred to as subunits 135 without distinction) for each radio circuit 102. The subunits 135 ₁ to 135 _n include space-time filter units 131 ₁ to 131 _n (hereinafter sometimes referred to as space-time filter units 131 without distinction), FO compensation units 132 ₁ to 132 _n (hereinafter sometimes referred to as FO compensation units 132 without distinction), and CP removal units 133 ₁ to 133 _n (hereinafter sometimes referred to as CP removal units 133 without distinction).

Each subunit 135 corresponds to one of the multiple radio circuits 102, and performs user separation using a space-time filter from the baseband signal obtained by frequency-converting the training signal acquired from each radio circuit 102, performs frequency offset compensation for each user stream, and removes CP and performs DFT. The output frequency-domain user streams are then added together, and frequency-domain equalization is performed for each user stream.

The time-space filter control unit 141 determines the coefficients of the time-space filter from the training signals acquired from the multiple radio circuits 102. Here, a baseband signal having a frequency offset with respect to the oscillation frequency of the LO 121 of the radio circuit appears to have a phase rotation over time compared to a baseband signal having no frequency offset. For this reason, the time-space filter control unit 141 sets the filter coefficients for each radio circuit 102 with a phase rotation according to the frequency offset, thereby enabling the time-space filter unit 131 to perform user separation while compensating for the frequency offset of the radio circuit 102.

<Other embodiments>
The invention is not limited to the above-described embodiment, and various modifications and variations are possible within the scope of the gist of the invention.

For example, in this embodiment, the description has been given assuming that each antenna 101 is connected to a different wireless circuit 102. However, when multiple antennas 101 are connected to one wireless circuit 102, such as when an AP has multiple antennas, the multiple antennas 101 can perform frequency conversion of wireless signals without frequency offset. For this reason, the signal acquisition unit 130 may acquire baseband signals corresponding to the multiple antennas 101 from the wireless circuit 102. In this case, the signal acquisition unit 130 can identify the antennas 101 connected to the same wireless circuit 102 by acquiring the baseband signals, the identifiers of the wireless circuits 102, and the antenna indexes in association with each other. Note that the signal processing unit 103 that receives baseband signals corresponding to the multiple antennas from one wireless circuit 102 may use any of the multiple baseband signals to determine the coefficients of the space-time filter and the frequency offset.

In addition, at least a part of the functions of the signal processing unit 103 according to this embodiment may be realized by a plurality of signal processing devices. In addition, at least a part of the functions of the signal processing unit 103 according to this embodiment may be provided by the radio circuit 102. For example, the subunit 135 in FIG. 4 may be disposed between the radio circuit 102 and the signal acquisition unit 130, on the side of the radio device that includes the radio circuit 102.

In addition, in Figures 2 to 4, the baseband signal acquired by the signal acquisition unit 130 is input to the space-time filter control unit 141, and after the space-time filter coefficients are determined, the signal is input to the FO determination unit 142 and then to the equalization control unit 143. However, the determination of the space-time filter filter coefficients, the determination of the frequency offset compensation value, and the determination of the equalization parameters of the equalization control unit may be performed in a reversed order or in parallel.

1: Wireless communication system, 10: Receiving device, 20: Transmitting device

Claims (11)

A communication device for receiving, by a plurality of antennas , a radio signal including a signal transmitted from a first transmitting device and a signal transmitted from a second transmitting device different from the first transmitting device , comprising:
acquiring a first reception signal obtained by frequency-converting the radio signal from a first radio circuit connected to a first antenna of the plurality of antennas;
acquiring a second reception signal obtained by frequency-converting the radio signal from a second radio circuit connected to a second antenna of the plurality of antennas;
A signal acquisition unit;
an output unit that receives the first and second received signals acquired by the signal acquisition unit as input and generates a plurality of output signals for each transmitting device;
a frequency offset compensation unit for compensating for a frequency offset for each of the plurality of output signals based on the first and second received signals;
A communication device comprising: The communication device according to claim 1, characterized in that the frequency offset compensation unit determines the amount of frequency offset to be compensated based on the frequency offset between the first received signal and the second received signal. The communication device according to claim 2, characterized in that the frequency offset compensation unit determines the amount of frequency offset to be compensated based on an average value of the frequency offset of the first received signal and the frequency offset of the second received signal. The communication device according to claim 2, characterized in that the frequency offset compensation unit identifies the signal strengths of the first and second received signals and determines the amount of frequency offset to compensate for the frequency offset of either the first or second received signal having a higher signal strength. The communication device according to claim 2, characterized in that the frequency offset compensation unit determines the amount of frequency offset to be compensated for based on a weighted average of the frequency offset of the first received signal and the frequency offset of the second received signal weighted by the signal strengths of the first and second received signals. 1. A communication device for receiving radio signals with a plurality of antennas, comprising:
acquiring a first reception signal obtained by frequency-converting the radio signal from a first radio circuit connected to a first antenna of the plurality of antennas;
acquiring a second reception signal obtained by frequency-converting the radio signal from a second radio circuit connected to a second antenna of the plurality of antennas;
A signal acquisition unit;
a first frequency offset compensation unit for compensating for a frequency offset between the first and second received signals;
an output unit for inputting an output of the first frequency offset compensation unit into a space-time filter to generate a plurality of output signals for each transmitter;
a second frequency offset compensation unit for compensating for a frequency offset for each of the plurality of output signals;
A communication device comprising: The communication device according to any one of claims 1 to 6, characterized in that the signal acquisition unit acquires each of the first and second received signals from separate external devices that are geographically distributed. A communication method for a communication device for receiving, by a plurality of antennas , a radio signal including a signal transmitted from a first transmitting device and a signal transmitted from a second transmitting device different from the first transmitting device , the method comprising the steps of:
acquiring a first reception signal obtained by frequency-converting the wireless signal from a first wireless circuit connected to a first antenna of the plurality of antennas;
acquiring a second reception signal obtained by frequency-converting the wireless signal from a second wireless circuit connected to a second antenna of the plurality of antennas;
inputting the first and second received signals into a space-time filter to generate a plurality of output signals for each transmitting device;
compensating for a frequency offset for each of the plurality of output signals based on the first and second received signals;
A communication method comprising: 1. A communication method for a communication device for receiving radio signals with a plurality of antennas, comprising:
acquiring a first reception signal obtained by frequency-converting the wireless signal from a first wireless circuit connected to a first antenna of the plurality of antennas;
acquiring a second reception signal obtained by frequency-converting the wireless signal from a second wireless circuit connected to a second antenna of the plurality of antennas;
compensating for a frequency offset between the first and second received signals;
inputting the first and second received signals, having been compensated for frequency offset, into a space-time filter to generate a plurality of output signals for each transmitting device;
compensating for a frequency offset for each of the plurality of output signals;
A communication method comprising: A communication device for receiving, by a plurality of antennas , a radio signal including a signal transmitted from a first transmitting device and a signal transmitted from a second transmitting device different from the first transmitting device ,
a first acquisition step of acquiring a first received signal obtained by frequency-converting the wireless signal from a first wireless circuit connected to a first antenna of the plurality of antennas;
a second acquisition step of acquiring a second received signal obtained by frequency-converting the wireless signal from a second wireless circuit connected to a second antenna of the plurality of antennas;
an output step of inputting the first and second received signals acquired in the first and second acquisition steps into a space-time filter to generate a plurality of output signals for each transmitting device;
a frequency offset compensating step of compensating for a frequency offset for each of the plurality of output signals based on the first and second received signals;
A program for executing a communication method comprising: A communication device for receiving radio signals by a plurality of antennas,
a first acquisition step of acquiring a first received signal obtained by frequency-converting the wireless signal from a first wireless circuit connected to a first antenna of the plurality of antennas;
a second acquisition step of acquiring a second received signal obtained by frequency-converting the wireless signal from a second wireless circuit connected to a second antenna of the plurality of antennas;
a first compensation step of compensating for a frequency offset between the first and second received signals acquired in the first and second acquisition steps;
an output step of inputting the first and second received signals, which have been compensated for the frequency offset, into a space-time filter to generate a plurality of output signals for each transmitting device;
a second compensating step of compensating for a frequency offset for each of the plurality of output signals;
A program for executing a communication method comprising:

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