COMMUNICATION DEVICE, COMMUNICATION METHOD, AND PROGRAM

Abstract

To prevent deterioration in reception performance of a communication device that receives a radio signal due to frequency offset between a plurality of radio circuits.SOLUTION: A communication device for receiving a radio signal with a plurality of antennas obtains a first received signal in which the radio signal is frequency-converted from a first radio circuit connected to a first antenna among the plurality of antennas, obtains a second received signal in which the radio signal is frequency-converted from a second radio circuit connected to a second antenna among the plurality of antennas, generates a plurality of output signals for respective transmission devices using the obtained first and second received signals as inputs, and compensates for a frequency offset for each of the plurality of output signals based on the first and second received signals.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a communication device, a communication method, and a program for receiving radio signals using a plurality of antennas that are arranged in a distributed manner. [Background technology]

[0002] When radio signals are transmitted from geographically dispersed user terminals or other transmitting points to multiple receiving antennas concentrated in one location, differences in propagation delays occur due to the propagation environment (link) 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 radio signals from user terminals using a space-time filter. In addition, as differences occur in the frequencies of the radio signals transmitted from each user terminal, frequency offset compensation is performed during demodulation and decoding on the receiving side.

[0003] 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. Based on these estimated values, the coefficients (weights) of the space-time filter are set, and the weights are superimposed on the signal received in the specific reception processing period to absorb the propagation delay difference and separate the received signal into streams for each user. After that, the frequency offset is compensated for for each user stream, and OFDM demodulation is performed. [Prior art documents] [Non-patent literature]

[0004] [Non-Patent Document 1] T. Tang and RW 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 Summary of the Invention [Problem to be solved by the invention]

[0005] 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 for demodulation 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 a case, a frequency offset may occur between multiple wireless communication circuits, causing a frequency shift in the baseband signal after frequency conversion, resulting in a problem of reduced reception performance.

[0006] The present invention has been made in consideration of the above-mentioned problems, and has an object to prevent a decrease in the reception performance of a communication device that receives radio signals due to a frequency offset between a plurality of radio circuits. [Means for solving the problem]

[0007] In order to achieve the above object, a communication device according to one aspect of the present invention has a plurality of antennas. , 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 communication device for receiving a radio signal, 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; 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: Effect of the Invention

[0008] According to the present invention, it is possible to prevent degradation of reception performance caused by frequency offsets between a plurality of receiving antennas. [Brief description of the drawings]

[0009] [Figure 1] FIG. 1 is a diagram showing a communication system including a communication device according to an embodiment of the present invention. [Diagram 2] FIG. 1 is a configuration diagram of a communication device according to a first embodiment. [Diagram 3] FIG. 11 is a configuration diagram of a communication device according to a second embodiment. [Figure 4] FIG. 13 is a configuration diagram of a communication device according to a third embodiment. [Diagram 5] 5 is a flowchart showing an example of a process executed by the communication device according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0010] Hereinafter, the embodiments will be 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 a number of features, not all of these features are essential to the invention, and the 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 duplicated descriptions are omitted.

[0011] 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, for the sake of simplicity, three transmitting devices and one receiving device are shown, but the number of these devices is not limited, and naturally more transmitting devices and receiving devices may be present.

[0012] The receiving device 10 according to the present 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 later 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.

[0013] Next, the configuration of the receiving device 10 will be described with reference to FIG.

[0014] The receiving device 10 includes a plurality of antennas 1011 to 101 n (hereinafter, sometimes referred to as antenna 101 without distinction).

[0015] Each antenna 101 is connected to a local oscillator (LO) 1211-121 n (hereinafter, sometimes referred to as LO 121 without distinction) n(hereinafter, they may be referred to as radio circuit 102 without distinction). Radio circuit 102 frequency-converts the radio signal received from antenna 101 to a baseband signal and transmits it to signal processing unit 103. Note that, although only the LO 121 and a mixer are illustrated in Fig. 2, radio circuit 102 may include additional high-frequency elements such as an amplifier and a high-frequency filter.

[0016] The signal processing unit 103 includes a signal acquisition unit 130, spatio-temporal filter units 1311 to 131 m (hereinafter, they may be referred to as the space-time filter unit 131 without distinction), and frequency offset (FO) compensation units 1321 to 132 m (hereinafter, they may be referred to as frequency offset compensation unit 132 without distinction), and cyclic prefix (CP) removal units 1331 to 1333. m (hereinafter, sometimes referred to as CP removal unit 133 without distinction), and frequency domain equalization units 1341 to 134 m (hereinafter, sometimes referred to as frequency domain equalization unit 134 without distinction).

[0017] 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 control parameters.

[0018] The space-time filter unit 131 is an output unit that receives baseband signals acquired from multiple radio circuits 102 in the order in which they were sampled, and outputs an output signal (user stream) obtained by separating the baseband signals into users for each transmitting device 20.

[0019] The CP removal unit 133 detects 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 by a discrete Fourier transform (DFT).

[0020] The frequency domain equalization unit 134 performs equalization of the signal data in the frequency domain on the frequency series signal data based on the signal strength of the pilot frequency included in the signal data by the transmitting device 20, or the like.

[0021] Since the known technology described in Non-Patent Document 1 can be applied to the CP removal unit 133 and the frequency domain equalization unit 134, a detailed description thereof will be omitted.

[0022] The signal processing unit 103 also includes a control unit 104. The control unit 104 includes a space-time filter control unit 141, an FO decision unit 142, and an equalization control unit 143.

[0023] The space-time filter control unit 141 determines filter coefficients of the space-time filter unit 131 based on the training signals transmitted from each transmitting device 20, as described below.

[0024] The FO determination unit 142 identifies a frequency offset with respect to the transmitting device 20 based on the training signals transmitted from each transmitting device 20, and compensates for the frequency offset. The FO determination unit 142 according to this embodiment estimates a frequency offset for each antenna 101 based on signal data of the training signals received by all antennas 101, and determines the amount of frequency offset compensated for by the FO compensation unit 132.

[0025] The equalization control unit 143 determines the signal strength for each subcarrier based on the training signal transmitted from each transmitting device 20, and performs channel equalization.

[0026] (Space-time filter control unit) Next, a control example of the space-time filter control unit 141 will be described. In the case where there are M transmission devices 20 that transmit signals to the reception device 10 and the reception device 10 has n antennas 101, the mth transmission device 20 m (1≦m≦M) and the jth receiving antenna 101 j (1≦j≦n) TIFF0007640410000001.tif2046 (l=0~ν), the Toeplitz matrix representing the channel between the transmitting and receiving antennas is TIFF0007640410000002.tif2228 can be expressed by the following formula 1.

[0027]

number

[0028] In this case, the jth receiving antenna 101 j The filter coefficients for user separation to extract the signal from the m-th transmitting device 20 from the received signal are Assuming that the data stream is TIFF0007640410000004.tif2125, 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.

[0029]

number

[0030] where TIFF0007640410000006.tif2062 is the frequency offset between the transmitter and receiver, TIFF0007640410000007.tif2354 is an orthogonal matrix representing the phase rotation caused by the frequency offset, and can be expressed by the following Equation 3.

[0031]

number

[0032] Such filter coefficients By obtaining TIFF0007640410000009.tif2125, 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.

[0033] (FO Judgment Unit) Next, an example of processing by the FO determination unit 142 will be described. Non-Patent Document 1 describes that the radio circuits 102 of all receiving antennas 101 operate at the same frequency. In other words, Non-Patent Document 1 stipulates that multiple receiving antennas are concentrated in one location, and that the radio circuits 102 operate based on a signal supplied from one local oscillator. For this reason, the operating frequencies of multiple radio circuits are the same, and Δ i,j = Δ i In contrast, the receiver 10 according to the present embodiment is based on the premise that a plurality of antennas 101 and radio circuits 102 are distributed and therefore operates on signals supplied from different local oscillators. For this reason, the two radio circuits 102 may operate on different frequencies, and therefore, Δ i,j = Δ i may not hold.

[0034] 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, it is possible to identify the frequency offset between the multiple radio circuits 102 by acquiring the baseband signals of the same radio signal from the multiple radio circuits 102 and identifying the frequency offset between the baseband signals.

[0035] The FO determination unit 142 determines the frequency offset Δ i,j Here, a frequency offset exists for each combination of the transmitting device 20 and the 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, the frequency offset Δ i,j If the frequency offset Δ i,j Based on this, the frequency offset Δ i Determine the following.

[0036] In one example, the FO determination unit 142 determines the frequency offset Δ i,j (j=0 to n), the frequency offset Δ i Determine the following.

[0037] For example, the frequency offset Δ iAlternatively, the received power P i,j Identify the same training signal, i.e., i has the same P i,j Identify the maximum value of P i,j For j' where j=0~n, Δ i,j = Δ i,j' It may be determined that.

[0038]

number

[0039] Also, for example, each frequency offset Δ i,j The received power of the training signal P i,j The frequency offset Δi may be determined based on a weighted average with weights according to the following Equation 5:

[0040]

number

[0041] 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 receiving performance due to frequency offset between radio circuits.

[0042] Next, an example of processing executed by the receiving device 10 according to the present 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 a memory during a period in which the receiving device 10 transmits a training signal from the transmitting device 20.

[0043] 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 an amplifier in the radio circuit 102, may also be acquired. Also, in S501, an identifier of the radio circuit 102, etc. may be acquired.

[0044] Next, in S502, the signal processing unit 103 identifies a 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 between the baseband signals.

[0045] Next, in S503, the signal processing unit 103 determines the coefficients of a space-time filter for separating into 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.

[0046] Next, in S505, the equalization control unit 143 determines equalization parameters to be set in the frequency domain equalization unit 134.

[0047] 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.

[0048] <Second embodiment> Next, the configuration of a communication device according to the second embodiment will be described with reference to FIG.

[0049] The communication device 10 according to the second embodiment includes second FO compensation units 1221 to 1222 between the space-time filter unit 131 and the radio circuit. n (hereinafter, sometimes referred to without distinction as the second FO compensation unit 122) and a second FO determination unit 144. The second FO compensation unit 122 performs frequency offset compensation for 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.

[0050] 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.

[0051] 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.

[0052] 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.

[0053] The coefficients of the space-time 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 the multiple antennas 101.

[0054] 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 transmission devices after user separation by the space-time filter, which allows the baseband signal to be treated as having no frequency offset after the space-time filter.

[0055] 3, the signal processing unit 103 is shown as acquiring a baseband signal after the frequency offset between the radio circuits is compensated for by the signal acquiring unit 130. However, the second FO compensation unit 122 may be disposed between the signal acquiring 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.

[0056] As described above, the communication device according to the present embodiment compensates for frequency offsets 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 offsets compensated for. This makes it possible to apply known techniques to user separation and frequency offset compensation for each transmitting device.

[0057] <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.

[0058] The communication device 10 according to this embodiment includes subunits 1351 to 135 for each radio circuit 102. n (hereinafter, they may be referred to as subunit 135 without distinction). n The spatio-temporal filter units 1311 to 131 n (hereinafter, they may be referred to as the spatio-temporal filter unit 131 without distinction), and the FO compensation units 1321 to 132 n(hereinafter, sometimes referred to as FO compensation unit 132 without distinction), and CP removal units 1331 to 1333 n (hereinafter, sometimes referred to as CP removal unit 133 without distinction).

[0059] Each subunit 135 corresponds to each of the multiple radio circuits 102, 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, removes CP and performs DFT, and then adds up the output frequency-domain user streams to perform frequency-domain equalization for each user stream.

[0060] 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 rotated 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.

[0061] <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.

[0062] For example, in the present embodiment, the description has been given assuming that each antenna 101 is connected to a different radio circuit 102. However, when the multiple antennas 101 are connected to one radio circuit 102, such as when an AP has multiple antennas, the multiple antennas 101 can perform frequency conversion of radio signals without a frequency offset. For this reason, the signal acquisition unit 130 may acquire baseband signals corresponding to the multiple antennas 101 from the radio circuit 102. In this case, the signal acquisition unit 130 can identify the antennas 101 connected to the same radio circuit 102 by acquiring the baseband signals, the identifiers of the radio circuits 102, and the indexes of the antennas in association with each other. Note that the signal processing unit 103, which has received baseband signals corresponding to the multiple antennas from one radio circuit 102, may use any of the multiple baseband signals to determine the coefficients of the space-time filter and the frequency offset.

[0063] At least a part of the functions of the signal processing unit 103 according to the present embodiment may be realized by a plurality of signal processing devices. At least a part of the functions of the signal processing unit 103 according to the present embodiment may be provided in the radio circuit 102. For example, the subunit 135 in Fig. 4 may be disposed between the radio circuit 102 and the signal acquiring unit 130, on the side of the radio device including the radio circuit 102.

[0064] 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 coefficients of the space-time filter 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 filter coefficients of the space-time filter, the determination of the compensation value for the frequency offset, and the determination of the equalization parameters of the equalization control unit may be performed in a reversed order or in parallel. [Explanation of symbols]

[0065] 1: wireless communication system, 10: receiving device, 20: transmitting device

Claims

1. 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:

2. 2. The communication device of claim 1, wherein the frequency offset compensation unit determines an amount of frequency offset to compensate based on a frequency offset between the first received signal and the second received signal.

3. 3. The communication device according to claim 2, wherein the frequency offset compensation unit determines an amount of frequency offset to be compensated for based on an average value of the frequency offset of the first received signal and the frequency offset of the second received signal.

4. 3. The communication device of claim 2, wherein the frequency offset compensation unit identifies signal strengths of the first and second received signals and determines an amount of frequency offset to compensate for the frequency offset of one of the first and second received signals having a higher signal strength.

5. 3. The communication device according to claim 2, wherein the frequency offset compensation unit determines an 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.

6. 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:

7. 7. The communication device according to claim 1, wherein the signal acquiring unit acquires the first and second received signals from separate external devices that are geographically distributed.

8. 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 radio signal from a second radio 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:

9. 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 radio signal from a second radio 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:

10. 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:

11. 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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