JP4646682B2 - Calibration method and radio apparatus and communication system using the same - Google Patents

Description

  The present invention relates to a calibration technique, and more particularly to a calibration method for correcting mismatches in a plurality of antennas, and a radio apparatus and a communication system using the same.

  An OFDM (Orthogonal Frequency Division Multiplexing) modulation scheme, which is one of the multicarrier schemes, is a communication scheme that enables high-speed data transmission and is strong in a multipath environment. This OFDM modulation scheme is applied to IEEE802.11a, g and HIPERLAN / 2, which are standardization standards for wireless LAN (Local Area Network). Since burst signals in such a wireless LAN are generally affected by frequency selective fading, the receiving apparatus dynamically performs transmission path estimation.

In order for the receiving apparatus to perform transmission path estimation, two types of known signals are provided in the burst signal. One is a known signal provided for all carriers at the head of the burst signal, which is a so-called preamble or training signal. The other is a known signal provided for some of the carriers in the data section of the burst signal, which is a so-called pilot signal (see, for example, Non-Patent Document 1).
Sine Coleri, Mustafa Ergen, Anuj Puri, and Ahmad Bahai, "Channel Estimation Techniques Based on Pilot Arrangement in OFDM Systems", IbnEstemEs. 48, no. 3, pp. 223-229, Sept. 2002.

  One technique for effectively using frequency resources in wireless communication is an adaptive array antenna technique. Adaptive array antenna technology controls the directivity pattern of an antenna by controlling the amplitude and phase of a signal corresponding to each of a plurality of antennas (hereinafter, this directivity pattern is referred to as an “adaptive pattern”) ). A technique for increasing the data rate by such an adaptive array antenna technique is a MIMO (Multiple Input Multiple Output) system. In the MIMO system, each of the transmission device and the reception device includes a plurality of antennas, and sets a channel corresponding to each antenna. Therefore, the MIMO system improves the data rate by setting channels up to the maximum number of antennas for communication between the transmission device and the reception device. Furthermore, if an OFDM modulation system is combined with such a MIMO system, the data rate is further increased.

  A combination of antenna directivity patterns in the transmission apparatus and the reception apparatus in the MIMO system is shown as follows, for example. One is a case where the antenna of the transmitting apparatus has an omni pattern and the antenna of the receiving apparatus has an adaptive pattern. Another is the case where both the antenna of the transmitting device and the antenna of the receiving device have adaptive patterns. The former can simplify the system, but the latter can control the antenna directivity pattern in more detail, thereby improving the characteristics. In the latter case, a known signal for transmission path estimation is provided in advance from the receiving apparatus so that the transmitting apparatus performs adaptive array signal processing for transmission. Further, in order to improve the accuracy of adaptive array antenna control, the transmission apparatus has transmission path characteristics corresponding to all combinations between a plurality of antennas included in the transmission apparatus and a plurality of antennas included in the reception apparatus. Should get. Therefore, the receiving apparatus transmits a known signal for channel estimation from all antennas. Hereinafter, a known signal for channel estimation transmitted from a plurality of antennas is referred to as a “training signal” regardless of the number of antennas to be used for data communication.

  When data is arranged after the training signal, if the number of antennas to which the training signal is transmitted differs from the number of antennas to which the data is transmitted, the signal strength for the training signal and the signal strength for the data on the receiving side. There will be a difference. If this difference increases, the signal strength for at least one of the training signal and the data cannot be appropriately controlled by the AGC. As a result, transmission path estimation by the training signal and data reception characteristics deteriorate. In order to suppress such deterioration, the transmission side of the training signal is directed to the data to be transmitted and the training signal (hereinafter, each of the training signals and data processed in parallel or a group is referred to as “series”). By multiplying the steering matrix, the training signal multiplied by the steering matrix and the data increased in number up to the number of training signals are generated.

  Under such circumstances, the present inventor has come to recognize the following problems. When a radio apparatus including a transmission apparatus performs adaptive array signal processing at the time of transmission, a mismatch between an analog circuit for transmission and an analog circuit for reception (hereinafter simply referred to as “mismatch”) is an antenna unit. If they are different from each other, the directivity pattern at the time of transmission is different from the desired one. That is, the wireless device calculates a weight for forming a directivity pattern at the time of transmission based on the received signal, but is not a directivity pattern to be realized by the weight due to a mismatch different for each antenna. A directivity pattern is realized. Therefore, calibration for a plurality of antennas is required. Such calibration should be feasible even under conditions where the steering matrix as described above is applied.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a calibration technique for executing calibration for a plurality of antennas even when a steering matrix is applied.

  In order to solve the above-described problem, in a radio apparatus according to an aspect of the present invention, a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and at least one to be transmitted Is multiplied by the first steering matrix and then multiplied by a calibration coefficient held in advance and then transmitted to the communication target wireless device, and the communication target wireless device is multiplied by the second steering matrix. A communication unit that receives at least one sequence, an influence of a transmission function in the wireless device to be communicated, a second steering matrix, a wireless transmission path characteristic from the wireless device to be communicated, The first matrix reflecting the influence of the reception function of the receiver, the influence of the reception function in the wireless device to be communicated, the first steering matrix, the communication pair A first derivation unit for receiving a second matrix reflecting a wireless transmission characteristic to the wireless device, an influence of a transmission function in the communication unit, and an influence of a calibration coefficient held in advance from the wireless device to be communicated; and a communication unit Via the wireless device to be communicated, the identification information corresponding to the second steering matrix in the wireless device to be communicated and corresponding to any one of a plurality of types of second steering matrices is provided. A receiving unit, a second steering matrix identified based on the identification information received in the receiving unit, a first matrix derived in the first deriving unit, a second matrix received in the first deriving unit, and a communication unit And a second deriving unit for deriving a calibration coefficient for the wireless device to be communicated from the first steering matrix.

  According to this aspect, since the identification number corresponding to the second steering matrix is received, a reduction in transmission efficiency for notifying the second steering matrix can be suppressed, and the second steering matrix corresponding to the received identification number is used. Therefore, it is possible to improve the accuracy of calibration for the wireless device to be communicated.

  The identification information received by the reception unit indicates that the second steering matrix is a unit matrix, and the second derivation unit determines that the inverse matrix of the first steering matrix and the second steering matrix are unit matrices. There may be included means for multiplying the second matrix, a transposed matrix resulting from the multiplication, and means for deriving a calibration coefficient for the wireless device to be communicated by dividing each component of the first matrix. In this case, if it is recognized that the second steering matrix is a unit matrix, the calibration coefficient is derived by a process corresponding thereto, so that the accuracy of the calibration coefficient can be improved.

  The identification information received in the reception unit indicates that the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift on each of the rows of the orthogonal matrix. When the second steering matrix includes an orthogonal matrix and a matrix for applying an independent time shift to each of the rows of the orthogonal matrix, the derivation unit and the inverse matrix of the first steering matrix and the second matrix Means for generating a first multiplication result from the matrix, means for generating a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix, a transposed matrix of the first multiplication result, and a second multiplication result. Means for deriving a calibration coefficient for the wireless device to be communicated by dividing the components. In this case, when it is recognized that the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix, a calibration coefficient is obtained by a process corresponding thereto. Since it is derived, the accuracy of the calibration coefficient can be improved.

  Another aspect of the present invention is also a wireless device. The apparatus defines a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas, and after multiplying the first steering matrix by at least one sequence to be transmitted, A communication unit that performs transmission to the communication target wireless device after multiplying the held calibration coefficient and receives at least one sequence multiplied by the second steering matrix in the communication target wireless device; and a communication unit The first matrix reflecting the influence of the transmission function in the wireless device to be communicated, the second steering matrix, the characteristics of the wireless transmission path from the wireless device to be communicated, the influence of the reception function in the communication unit is derived And the influence of the reception function in the wireless device to be communicated, the first steering matrix, the wireless transmission characteristics to the wireless device to be communicated, the transmission in the communication unit The first derivation unit that receives the second matrix reflecting the influence of the performance and the calibration coefficient held in advance from the wireless device to be communicated, and the second steering matrix in the communication unit are an orthogonal matrix and an orthogonal matrix A matrix for applying an independent time shift to each of the rows, a storage unit storing an orthogonal matrix of the second steering matrix, an orthogonal matrix stored in the storage unit, and a first derivation unit A second derivation unit for deriving a calibration coefficient for the wireless device to be communicated based on the first matrix derived in step 1, the second matrix received in the first derivation unit, and the first steering matrix in the communication unit; Is provided.

  According to this aspect, when the second steering matrix includes an orthogonal matrix and a matrix for applying an independent time shift to each of the rows of the orthogonal matrix, for each of the rows of the orthogonal matrix Since the calibration coefficient is derived without using the information about the matrix for performing the independent time shift, the matrix for performing the independent time shift for each of the rows of the orthogonal matrix in the wireless device to be communicated. Can be set arbitrarily.

  A second derivation unit; means for generating a first multiplication result from the inverse matrix of the first steering matrix and the second matrix; means for generating a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix; Means for deriving a calibration coefficient for the wireless device to be communicated by dividing the transposed matrix of the first multiplication result and the components of the second multiplication result may be included. In this case, since the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix, the calibration coefficient is derived by processing. The accuracy of the calibration coefficient can be improved.

  Yet another embodiment of the present invention is also a wireless device. The apparatus defines a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas, and after multiplying the first steering matrix by at least one sequence to be transmitted, A communication unit that performs transmission to the communication target wireless device after multiplying the held calibration coefficient and receives at least one sequence multiplied by the second steering matrix in the communication target wireless device; and a communication unit The first matrix reflecting the influence of the transmission function in the wireless device to be communicated, the second steering matrix, the characteristics of the wireless transmission path from the wireless device to be communicated, the influence of the reception function in the communication unit is derived And the influence of the reception function in the wireless device to be communicated, the first steering matrix, the wireless transmission characteristics to the wireless device to be communicated, the transmission in the communication unit In the first derivation unit that receives the second matrix reflecting the influence of the performance and the previously held calibration coefficient from the wireless device to be communicated, the first matrix derived in the first derivation unit, and the first derivation unit Based on the received second matrix, a specifying unit that specifies the format of the second steering matrix, a second steering matrix specified by the specifying unit, a first matrix derived by the first deriving unit, and a first derivation And a second deriving unit for deriving a calibration coefficient for the wireless device to be communicated from the first steering matrix in the communication unit.

  According to this aspect, since the format of the second steering matrix is specified based on the first matrix and the second matrix, the format of the second steering matrix can be recognized while suppressing a decrease in transmission efficiency, and calibration is performed by processing corresponding thereto. Since the calibration coefficient is derived, the accuracy of the calibration coefficient can be improved.

  In the specifying unit, when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is used as the third matrix, two elements having the same row or column are selected from the first matrix. Means for deriving a ratio of the two elements, means for selecting two elements of the third matrix so as to correspond to the two elements, and deriving a ratio of the selected two elements, and a first matrix And means for identifying that the second steering matrix is a unit matrix when the ratio of the two elements in is the same as the ratio of the two elements in the third matrix. In this case, since the second steering matrix is specified as a unit matrix based on the first matrix and the second matrix, additional information is not required, and a decrease in transmission efficiency can be suppressed.

  In the specifying unit, when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is the third matrix, and the multiplication result of the inverse matrix of the orthogonal matrix and the first matrix is the fourth matrix, In the fourth matrix, two elements having the same row or column are selected, a means for deriving the ratio of the elements, and a ratio of the two elements of the third matrix so as to correspond to the two elements. Selecting and deriving the ratio of the two selected elements, the ratio of the two elements in the fourth matrix and the ratio of the two elements in the third matrix being the same, the second steering matrix is non- And a means for specifying that the matrix is a unit matrix. In this case, since the second steering matrix is specified as a non-unit matrix based on the first matrix and the second matrix, additional information is not required, and a decrease in transmission efficiency can be suppressed.

  The second deriving unit, when the identifying unit identifies that the second steering matrix is a unit matrix, means for multiplying the inverse matrix of the first steering matrix and the second matrix, a transposed matrix as a result of multiplication, Means for deriving a calibration coefficient for a wireless device to be communicated by dividing each component of the first matrix may be included. In this case, when the second steering matrix is recognized as a unit matrix, the calibration coefficient is derived by a process corresponding thereto, so that the accuracy of the calibration coefficient can be improved.

  When the specifying unit specifies that the second steering matrix is a non-unit matrix, the second steering matrix includes an orthogonal matrix and a matrix for applying an independent time shift to each of the rows of the orthogonal matrix. The second derivation unit generates a first multiplication result from the inverse matrix of the first steering matrix and the second matrix, and generates a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix. And means for deriving a calibration coefficient for the wireless device to be communicated by dividing the transposed matrix of the first multiplication result and each component of the second multiplication result. In this case, when the second steering matrix is recognized as a non-unit matrix, the calibration coefficient is derived by a process corresponding to the second steering matrix, so that the accuracy of the calibration coefficient can be improved.

  Yet another embodiment of the present invention is a communication system. In this communication system, a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and after multiplying at least one sequence to be transmitted by the first steering matrix, A first radio apparatus that transmits a signal generated by multiplying a calibration coefficient held in advance, and a second radio apparatus that transmits a signal generated by multiplying at least one sequence to be transmitted by a second steering matrix With. The second wireless device, based on the signal received from the first wireless device, the influence of the transmission function of the first wireless device, the first steering matrix, the wireless transmission characteristics from the first wireless device, the reception of the second wireless device Means for deriving the first matrix reflecting the influence of the function and the influence of the calibration coefficient held in advance, and transmitting the derived first matrix to the first radio apparatus; and identification information corresponding to the second steering matrix And means for transmitting identification information corresponding to any one of a plurality of types of second steering matrices defined to the first radio apparatus. The first radio device is based on the signal received from the second radio device, the influence of the transmission function in the second radio device, the second steering matrix, the radio transmission path characteristics from the second radio device, the first radio device From the means for deriving the second matrix reflecting the influence of the reception function at the second steering matrix, the second steering matrix specified based on the identification information, the first matrix, the second matrix, and the first steering matrix, Means for deriving calibration coefficients for the two wireless devices;

  In the first radio apparatus, when the received identification information indicates that the second steering matrix is a unit matrix, means for multiplying the inverse matrix of the first steering matrix by the first matrix, and the multiplication result Means for deriving a calibration coefficient for the second radio apparatus by dividing each component of the transposed matrix and the second matrix. In the first radio apparatus, the received identification information indicates that the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each row of the orthogonal matrix. A means for generating a first multiplication result from the inverse matrix of the first steering matrix and the first matrix, a means for generating a second multiplication result from the inverse matrix of the orthogonal matrix and the second matrix, Means for deriving a calibration coefficient for the second wireless device by dividing the transposed matrix of the multiplication result and each component of the second multiplication result may be included.

  Yet another aspect of the present invention is also a communication system. In this communication system, a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and after multiplying at least one sequence to be transmitted by the first steering matrix, A first radio apparatus that transmits a signal generated by multiplying a calibration coefficient held in advance, and a second radio apparatus that transmits a signal generated by multiplying at least one sequence to be transmitted by a second steering matrix With. The second wireless device, based on the signal received from the first wireless device, the influence of the transmission function of the first wireless device, the first steering matrix, the wireless transmission characteristics from the first wireless device, the reception of the second wireless device After deriving the first matrix reflecting the influence of the function and the previously held calibration coefficient, the first matrix is transmitted to the first radio apparatus, and the first radio apparatus is transmitted from the second radio apparatus. Based on the received signal, the influence of the transmission function in the second wireless device, the second steering matrix, the characteristics of the wireless transmission path from the second wireless device, and the influence of the reception function in the first wireless device are reflected. Means for deriving two matrices, means for identifying the format of the second steering matrix based on the received first matrix, the derived second matrix, the identified second steering matrix, and the first matrix; From the second matrix and the first steering matrix And means for deriving a calibration factor for the second wireless device.

  In the first radio apparatus, when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the first matrix is the third matrix, two elements of the second matrix having the same row or column are Means for selecting and deriving a ratio of the two elements, means for selecting two elements of the third matrix so as to correspond to the two elements, and deriving a ratio of the selected two elements; Means may be included for specifying that the second steering matrix is a unit matrix when the ratio of the two elements in the two matrices is the same as the ratio of the two elements in the third matrix. In the first radio apparatus, the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the first matrix is the third matrix, and the multiplication result of the inverse matrix of the orthogonal matrix and the second matrix is the fourth matrix. In the fourth matrix, two elements having the same row or column are selected, a means for deriving a ratio of the elements, and two elements of the third matrix so as to correspond to the two elements. If the ratio is selected, the means for deriving the ratio of the two selected elements, the ratio of the two elements in the fourth matrix and the ratio of the two elements in the third matrix are the same, the second steering matrix is And means for specifying that it is a non-unit matrix.

  The first radio apparatus, when the second steering matrix is specified to be a unit matrix, means for multiplying the inverse matrix of the first steering matrix and the first matrix, the transposed matrix and the second matrix of the multiplication results And means for deriving a calibration coefficient for the second wireless device by dividing each component. In the first radio apparatus, when it is specified that the second steering matrix is a non-unit matrix, the second steering matrix is a matrix for performing independent time shift on each of the orthogonal matrix and the rows of the orthogonal matrix. Means for generating a first multiplication result from the inverse matrix of the first steering matrix and the first matrix, means for generating a second multiplication result from the inverse matrix of the orthogonal matrix and the second matrix, Means for deriving a calibration coefficient for the second radio apparatus by dividing the transposed matrix of the first multiplication result and each component of the second multiplication result may be included.

  Yet another embodiment of the present invention is a calibration method. In this method, a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and after multiplying the first steering matrix by at least one sequence to be transmitted, In the wireless device that performs the transmission to the wireless device to be communicated after multiplying the held calibration coefficient and receives at least one sequence multiplied by the second steering matrix in the wireless device to be communicated, A calibration method for deriving a calibration coefficient for a wireless device in which the transmission function of the communication target wireless device is affected, the second steering matrix, the wireless transmission path characteristics from the communication target wireless device, and the main communication Deriving the first matrix reflecting the influence of the reception function in the device, and the wireless device to be communicated The second matrix that reflects the influence of the reception function, the first steering matrix, the wireless transmission characteristics to the communication target wireless device, the influence of the transmission function of the communication device, and the influence of the calibration coefficient held in advance Receiving from the wireless device to be communicated, and receiving from the wireless device to be communicated identification information corresponding to the second steering matrix and corresponding to any of a plurality of types of second steering matrices And deriving a calibration coefficient for the wireless device to be communicated from the second steering matrix, the first matrix, the second matrix, and the first steering matrix specified based on the identification information.

  The identification information received in the step of accepting indicates that the second steering matrix is a unit matrix, and the step of deriving the calibration coefficient is performed when the second steering matrix is a unit matrix. A step of multiplying the inverse matrix by the second matrix, and a step of deriving a calibration coefficient for the wireless device to be communicated by dividing each component of the transposed matrix and the first matrix resulting from the multiplication. Good.

  The identification information received in the step of receiving indicates that the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix. The step of deriving a coefficient includes: an inverse matrix of the first steering matrix when the second steering matrix includes an orthogonal matrix and a matrix for applying an independent time shift to each of the rows of the orthogonal matrix. Generating a first multiplication result from the first matrix, a step of generating a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix, a transposed matrix of the first multiplication result, and a second multiplication Deriving calibration coefficients for the wireless device to be communicated by dividing each component of the result.

  Yet another embodiment of the present invention is also a calibration method. In this method, a first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and after multiplying the first steering matrix by at least one sequence to be transmitted, In the wireless device that performs the transmission to the wireless device to be communicated after multiplying the held calibration coefficient and receives at least one sequence multiplied by the second steering matrix in the wireless device to be communicated, A calibration method for deriving a calibration coefficient for a wireless device in which the transmission function of the communication target wireless device is affected, the second steering matrix, the wireless transmission path characteristics from the communication target wireless device, and the main communication Deriving the first matrix reflecting the influence of the reception function in the device, and the wireless device to be communicated The second matrix that reflects the influence of the reception function, the first steering matrix, the wireless transmission characteristics to the communication target wireless device, the influence of the transmission function of the communication device, and the influence of the calibration coefficient held in advance Receiving from the wireless device; identifying a format of the second steering matrix based on the first matrix and the second matrix; the identified second steering matrix; the first matrix; the second matrix; And deriving a calibration coefficient for the wireless device to be communicated from the first steering matrix.

  The specifying step selects two elements having the same row or column from the first matrix when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is the third matrix. Deriving a ratio of the two elements, selecting two elements of the third matrix so as to correspond to the two elements, and deriving a ratio of the selected two elements; When the ratio of the two elements in the matrix and the ratio of the two elements in the third matrix are the same, the step of identifying that the second steering matrix is a unit matrix may be included. The specifying step is when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is the third matrix, and the multiplication result of the inverse matrix of the orthogonal matrix and the first matrix is the fourth matrix. Selecting two elements of the fourth matrix having the same row or column and deriving the ratio of the elements, and the ratio of the two elements of the third matrix so as to correspond to the two elements And deriving the ratio of the two selected elements, the ratio of the two elements in the fourth matrix and the ratio of the two elements in the third matrix are the same, the second steering matrix is Identifying a non-unit matrix.

  The step of deriving the calibration coefficient includes the step of multiplying the inverse matrix of the first steering matrix and the second matrix when the second steering matrix is identified as a unit matrix, the transposed matrix of the multiplication result, A step of deriving a calibration coefficient for the wireless device to be communicated by dividing each component of one matrix. When the specifying step determines that the second steering matrix is a non-unit matrix, the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix. The step of deriving the calibration coefficient includes generating a first multiplication result from the inverse matrix of the first steering matrix and the second matrix, a second multiplication from the inverse matrix of the orthogonal matrix and the first matrix A step of generating a result, and a step of deriving a calibration coefficient for the wireless device to be communicated by dividing each component of the transposed matrix of the first multiplication result and the second multiplication result may be included.

  It should be noted that any combination of the above-described constituent elements and a conversion of the expression of the present invention between a method, an apparatus, a system, a recording medium, a computer program, etc. are also effective as an aspect of the present invention.

  According to the present invention, calibration for a plurality of antennas can be executed even when a steering matrix is applied.

  Before describing the present invention in detail, an outline will be described. An embodiment of the present invention relates to a MIMO system including a base station device and a terminal device. Here, the base station apparatus performs beamforming transmission, but the terminal apparatus performs multiplication of the steering matrix without performing beamforming transmission. Note that the base station apparatus performs calibration for each terminal apparatus before performing beamforming. When executing the calibration, the base station apparatus performs the multiplication of the steering matrix without executing the beamforming transmission, similarly to the terminal apparatus. As described above, by multiplying the training signal and data included in at least one sequence to be transmitted by the steering matrix, the power difference on the receiving side of the training signal and data is reduced. The base station apparatus estimates transmission path characteristics from the training signal multiplied by such a steering matrix, and performs beamforming transmission while using the transmission path characteristics. The base station apparatus and the terminal apparatus perform calibration for the purpose of reducing mismatches that differ for each antenna. For this reason, calibration is required that can cope with a case where a steering matrix is applied to a training signal exchanged at the time of calibration. Further, in order to facilitate the device configuration of the terminal device, it is desirable that calibration for the terminal device is performed in the base station device. Therefore, in this embodiment, calibration is performed as follows.

  As a premise, it is assumed that the calibration for the base station apparatus has already been completed. In order to cause the terminal device to estimate the transmission path characteristics, the base station device transmits a training signal. The terminal apparatus estimates transmission path characteristics corresponding to combinations of a plurality of antennas of the base station apparatus and a plurality of antennas of the terminal apparatus (hereinafter, the transmission path characteristics corresponding to each combination are combined into a matrix format, etc. Is called "H matrix"). Further, the H matrix estimated in the terminal device corresponds to the transmission path characteristic of the downlink. Further, the terminal device transmits a training signal in order to cause the base station device to estimate the transmission path characteristics. At that time, the terminal device transmits the downlink H matrix as data. The terminal device may transmit the transposition of the H matrix as data. In that case, if the base station apparatus recognizes the transposition of the H matrix, the base station apparatus can execute the same operation as the operation described below. The base station apparatus estimates transmission path characteristics corresponding to combinations of a plurality of antennas of the base station apparatus and a plurality of antennas of the terminal apparatus as an H matrix. The H matrix corresponds to an uplink transmission path characteristic.

  Here, the transmission path characteristics included in the H matrix include the influence of the mismatch of the steering matrix and the analog circuit of the transmission / reception system, in addition to the transmission path characteristics as the radio transmission path. Hereinafter, such comprehensive transmission path characteristics are also simply referred to as transmission path characteristics. The base station apparatus performs calibration on the terminal apparatus using the uplink H matrix, downlink H matrix, and steering matrix in the base station apparatus, and derives a calibration coefficient. The calibration coefficient is used at the time of beamforming transmission to be executed later. When the calibration coefficient is derived by the processing as described above, the calibration coefficient may not be derived depending on the transmission path characteristics unless the base station apparatus grasps the steering matrix of the terminal apparatus. On the other hand, if the terminal device transmits the steering matrix to the base station device, the data transmission efficiency decreases.

  In order to solve such a problem, in the MIMO system according to the present embodiment, a plurality of types of steering matrices are defined in advance, and an identification number is assigned to each of the plurality of types of steering matrices. . The terminal apparatus transmits an identification number corresponding to the steering matrix to be used to the base station apparatus, and the base station apparatus grasps the steering matrix of the terminal apparatus from the received identification number. Further, the base station apparatus derives a calibration coefficient using the grasped steering matrix.

  FIG. 1 shows a spectrum of a multicarrier signal according to an embodiment of the present invention. In particular, FIG. 1 shows the spectrum of a signal in the OFDM modulation scheme. One of a plurality of carriers in the OFDM modulation scheme is generally called a subcarrier, but here, one subcarrier is designated by a “subcarrier number”. Here, as in the IEEE802.11a standard, 53 subcarriers from subcarrier numbers “−26” to “26” are defined. The subcarrier number “0” is set to null in order to reduce the influence of the DC component in the baseband signal. Each subcarrier is modulated by a variably set modulation scheme.

  As a modulation method, any one of BPSK (Binary Phase Shift Keying), QSPK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and 64QAM is used. Also, convolutional coding is applied to these signals as an error correction method. The coding rate of convolutional coding is set to 1/2, 3/4, and the like. Furthermore, the number of antennas used in the MIMO system is variably set. As a result, the data rate is also variably set by variably setting the modulation scheme, coding rate, and number of antennas.

  FIG. 2 shows a configuration of the communication system 100 according to the embodiment of the present invention. The communication system 100 includes a base station device 10 and a terminal device 90. The base station apparatus 10 includes a first antenna 12a, a second antenna 12b, a third antenna 12c, and a fourth antenna 12d that are collectively referred to as an antenna 12, and the terminal apparatus 90 is a first antenna that is collectively referred to as an antenna 14. 14a, the second antenna 14b, the third antenna 14c, and the fourth antenna 14d. In the downlink, the base station apparatus 10 corresponds to a transmission apparatus, and corresponds to a reception apparatus of the terminal apparatus 90. The uplink is the opposite of the downlink.

  Before describing the configuration of the communication system 100, an outline of a MIMO system will be described. It is assumed that the downlink is an object of explanation and data is transmitted from the base station apparatus 10 to the terminal apparatus 90. The base station apparatus 10 transmits different data from each of the first antenna 12a to the fourth antenna 12d. As a result, the data rate is increased. The terminal device 90 receives data from the first antenna 14a to the fourth antenna 14d. Further, the terminal device 90 independently demodulates the data transmitted from each of the first antenna 12a to the fourth antenna 12d by adaptive array signal processing.

  Here, since the number of antennas 12 is “4” and the number of antennas 14 is also “4”, the combination of transmission paths between the antennas 12 and 14 is “16”. A transmission path characteristic between the i-th antenna 12i and the j-th antenna 14j is denoted by hij. In the figure, the transmission line characteristic between the first antenna 12a and the first antenna 14a is h11, the transmission line characteristic between the first antenna 12a and the second antenna 14b is h12, the second antenna 12b and the first antenna. 14a, the transmission path characteristic between the second antenna 12b and the second antenna 14b is h22, and the transmission path characteristic between the fourth antenna 12d and the fourth antenna 14d is h44. Has been. Note that transmission lines other than these are omitted for the sake of clarity.

  The terminal device 90 operates so that data transmitted from the first antenna 12a to the second antenna 12b can be independently demodulated by adaptive array signal processing. Further, the base station apparatus 10 performs adaptive array signal processing from the first antenna 12a to the fourth antenna 12d during transmission. As described above, the base station apparatus 10 on the transmission side also executes adaptive array signal processing, thereby ensuring space division in the MIMO system. As a result, since interference between signals transmitted from the plurality of antennas 12 is reduced, this embodiment can improve communication quality. Note that the operations of the base station device 10 and the terminal device 90 may be reversed. As described above, when calibration is performed, the base station apparatus 10 transmits a training signal using the steering matrix without performing adaptive array signal processing.

Although details will be described later, in the configuration of the communication system 100 as described above, the calibration is executed as follows. The base station apparatus 10 defines a steering matrix Q (1). The base station device 10 multiplies the steering matrix Q (1) by at least one sequence to be transmitted, thereby generating training signals multiplied by the steering matrix and data whose number is increased to the number of training signals. Furthermore, the base station apparatus 10 transmits a signal generated by multiplying the calibration coefficient C _AUTO (1) held in advance. Here, the calibration coefficient C _AUTO (1) is a calibration coefficient derived by the base station apparatus 10 and corresponds to a calibration coefficient for an error between the antennas 12. The terminal device 90 transmits a signal generated by multiplying the training signal and data by the steering matrix Q (2).

Further, the terminal device 90 derives an H matrix based on the training signal received from the base station device 10. The H matrix includes the influence of the transmission function of the base station apparatus 10, the steering matrix Q (1), the wireless transmission characteristics from the base station apparatus 10, the influence of the reception function of the terminal apparatus 90, and the calibration coefficient C _AUTO (1). The effect of is reflected. Further, the terminal device 90 transmits the derived H matrix to the base station device 10. Note that a plurality of types of steering matrices Q (2) are defined, and identification information is added to the plurality of types of steering matrices Q (2). The terminal device 90 transmits an identification number corresponding to the steering matrix Q (2) to be used to the base station device 10. The base station apparatus 10 derives an H matrix based on the training signal received from the terminal apparatus 90. This H matrix reflects the influence of the transmission function at the terminal device 90, the steering matrix Q (2), the wireless transmission path characteristics from the terminal device 90, and the influence of the reception function at the base station device 10. Further, the base station apparatus 10 derives a calibration coefficient for the terminal apparatus 90 from the steering matrix Q (2), the two H matrices, and the steering matrix Q (1) specified based on the identification information.

  FIG. 3 shows the configuration of the base station apparatus 10. The base station apparatus 10 includes a first radio unit 20a, a second radio unit 20b, a fourth radio unit 20d, a processing unit 22, a modem unit 24, an IF unit 26, a control unit 30, and a storage unit 32, which are collectively referred to as a radio unit 20. including. Further, as signals, a first time domain signal 200a, a second time domain signal 200b, a fourth time domain signal 200d, which are collectively referred to as a time domain signal 200, a first frequency domain signal 202a, which is collectively referred to as a frequency domain signal 202, and a second time domain signal 200b. Includes a frequency domain signal 202b. Here, in order to clarify the explanation, the number “2” of data included in the sequence to be transmitted and the received sequence and the number “4” of training signals are fixed. However, these numbers may be adjusted adaptively. In the following description, the transmission operation corresponds to downlink communication, and the reception operation corresponds to uplink communication.

  As a reception operation, the radio unit 20 performs frequency conversion on a radio frequency signal received by the antenna 12 and derives a baseband signal. The radio unit 20 outputs the baseband signal as the time domain signal 200 to the processing unit 22. In general, baseband signals are formed by in-phase and quadrature components, so they should be transmitted by two signal lines. Here, only one signal line is used for the sake of clarity. Shall be shown. An AGC (Automatic Gain Control) and an A / D conversion unit are also included. As a transmission operation, the radio unit 20 performs frequency conversion on the baseband signal from the processing unit 22 and derives a radio frequency signal. Here, a baseband signal from the processing unit 22 is also shown as a time domain signal 200. The radio unit 20 outputs a radio frequency signal to the antenna 12. Further, a PA (Power Amplifier) and a D / A converter are also included. The time domain signal 200 is a multicarrier signal converted into the time domain, and is a digital signal. Further, the signal processed in the radio unit 20 forms a burst signal. In the burst format, a training signal is arranged in the preceding stage and data is arranged in the succeeding stage.

  As a receiving operation, the processing unit 22 converts each of the plurality of time domain signals 200 into the frequency domain, and performs adaptive array signal processing on the frequency domain signal. The processing unit 22 outputs the result of adaptive array signal processing as the frequency domain signal 202. One frequency domain signal 202 corresponds to data included in one sequence transmitted from a terminal device 90 (not shown). As a transmission operation, the processing unit 22 receives the frequency domain signal 202 as a frequency domain signal from the modem unit 24 and performs adaptive array signal processing. That is, beam forming is executed. Further, the processor 22 uses the calibration coefficient for the base station apparatus 10 and the calibration coefficient for the terminal apparatus 90 at the time of beamforming. Note that the base station apparatus 10 performs calibration for the terminal apparatus 90 before beamforming transmission. At that time, the processing unit 22 performs multiplication of the steering matrix without performing beamforming.

  The processing unit 22 converts the frequency domain signal into the time domain and outputs the time domain signal 200. It is assumed that the number of antennas 12 to be used in the transmission process is specified by the control unit 30. Here, the frequency domain signal 202, which is a frequency domain signal, includes a plurality of subcarrier components as shown in FIG. For the sake of clarity, it is assumed that the signals in the frequency domain are arranged in the order of subcarrier numbers to form a serial signal. Further, the calibration coefficient for the terminal device 90 and the calibration coefficient for the base station device 10 have different values for each antenna 12 unit. These coefficients are derived by the control unit 30.

  FIG. 4 shows the configuration of a signal in the frequency domain. Here, one combination of subcarrier numbers “−26” to “26” shown in FIG. 1 is referred to as an “OFDM symbol”. In the “i” th OFDM symbol, subcarrier components are arranged in the order of subcarrier numbers “1” to “26” and subcarrier numbers “−26” to “−1”. Also, the “i−1” th OFDM symbol is arranged before the “i” th OFDM symbol, and the “i + 1” th OFDM symbol is arranged after the “i” th OFDM symbol. And

  Returning to FIG. The modem unit 24 performs demodulation and decoding on the frequency domain signal 202 from the processing unit 22 as reception processing. Note that demodulation and decoding are performed in units of subcarriers. The modem unit 24 outputs the decoded signal to the IF unit 26. Further, the modem unit 24 performs encoding and modulation as transmission processing. The modem unit 24 outputs the modulated signal to the processing unit 22 as the frequency domain signal 202. It is assumed that the modulation scheme and the coding rate are specified by the control unit 30 during the transmission process.

  The IF unit 26 combines signals from the plurality of modulation / demodulation units 24 as a reception process to form one data stream. The IF unit 26 outputs a data stream. In addition, the IF unit 26 inputs one data stream as transmission processing and separates it. Further, the separated data is output to a plurality of modems 24.

The control unit 30 controls the timing of the base station apparatus 10 and the like. In addition, the control unit 30 derives a calibration coefficient for the terminal device 90 and a calibration coefficient for the base station device 10. _Assuming that the calibration coefficient C _AUTO (1) for the base station apparatus 10 has already been derived, the procedure for deriving the calibration coefficient for the terminal apparatus 90 will be briefly described. Derivation of the calibration coefficient C _AUTO (1) for the base station apparatus 10 will be described later. The calibration procedure described below is performed before beamforming transmission is executed on the transmission side.

As described above, the processing unit 22 or the like performs transmission after multiplying the training signal and data by the steering matrix Q (1) and then by multiplying the calibration coefficient C _AUTO (1) for the base station apparatus 10. Further, the processing unit 22 or the like receives at least one sequence multiplied by the steering matrix Q (2) in the terminal device 90 (not shown). This sequence corresponds to the training signal described above. Further, the processing unit 22 estimates the transmission path characteristics based on the training signal during adaptive array signal processing. The control unit 30 derives an uplink H matrix from the transmission path characteristics. The control unit 30 receives a downlink H matrix derived by a terminal device 90 (not shown).

  The control unit 30 is identification information corresponding to the steering matrix Q (2) in the terminal device 90 (not shown) via the processing unit 22 and the like, and among the steering matrices Q (2) defined in a plurality of types. The identification information corresponding to any one is received from the terminal device 90. Here, it is assumed that two types of matrices are defined as the steering matrix. One steering matrix is a unit matrix. Another steering matrix is formed by the product of an orthogonal matrix and a matrix (hereinafter referred to as “CDD (Cyclic Delay Diversity) matrix) for performing independent time shifts on each of the rows of the orthogonal matrix. Furthermore, the identification number “0” corresponds to the unit matrix, and the identification number “1” corresponds to the product of the orthogonal matrix and the CDD matrix, that is, if the identification number “0” is received, the control unit 30 The steering matrix Q (2) is identified as a unit matrix, and if the identification number “1” is received, the control unit 30 identifies that the steering matrix is a product of an orthogonal matrix and a CDD matrix. Are stored in the storage unit 32.

  FIG. 5 is a diagram illustrating the structure of data stored in the storage unit 32. As illustrated, a unit matrix “E” is associated with the identification number “0”, and a matrix “WF (2)” is associated with the identification number “1”. Here, “W” is a CDD matrix, and “F (2)” is a Fourier matrix. The Fourier matrix is one of orthogonal matrices. Returning to FIG.

  From the steering matrix Q (2) specified based on the received identification information, the derived uplink H matrix, the received downlink H matrix, and the steering matrix Q (1), the control unit 30 A calibration coefficient for the terminal device 90 not to be derived is derived. Note that the control unit 30 changes the method for deriving the calibration coefficient depending on whether the steering matrix Q (2) is a unit matrix or a product of an orthogonal matrix and a CDD matrix.

  Here, it is assumed that the variation amount of the calibration coefficient with respect to the base station apparatus 10 is small. Therefore, once the calibration coefficient for the base station apparatus 10 is derived, it is used for several days, for example. Therefore, it can be said that it is a quasi-static value. On the other hand, the calibration coefficient for the terminal device 90 is different for each terminal device 90. Therefore, the base station apparatus 10 uses the calibration coefficient for the terminal apparatus 90 while switching according to the terminal apparatus 90 with which it is communicating. The control unit 30 may store calibration coefficients for a plurality of terminal devices 90 and use calibration coefficients corresponding to the terminal devices 90 that are communicating.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of any computer, and in terms of software, it is realized by a program having a communication function loaded in the memory. Describes functional blocks realized by collaboration. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 6 shows the configuration of the processing unit 22. The processing unit 22 includes an FFT (Fast Fourier Transform) unit 50, a first synthesis unit 54a, a second synthesis unit 54b, a fourth synthesis unit 54d, a spatial dispersion unit 56, a transmission side correction unit 62, An IFFT unit 64 is included.

  The FFT unit 50 receives a plurality of time domain signals 200 and performs a Fourier transform on each of them to derive a frequency domain signal. As described above, signals corresponding to subcarriers are serially arranged in the order of subcarrier numbers as one frequency domain signal.

  The synthesizer 54 performs adaptive array signal processing on the frequency domain signal from the FFT unit 50. That is, array synthesis is executed. Here, it is assumed that the steering matrix is also applied to the signal transmitted from the terminal device 90, and the number of data before the steering matrix is applied in the terminal device 90 is “2”. Corresponding to this, out of the synthesizer 54, the first synthesizer 54a and the second synthesizer 54b output data. Further, the remaining combining unit 54 calculates transmission line characteristics in order to generate the above-described H vector.

  The synthesizing unit 54 includes a plurality of multipliers (not shown), and each of the plurality of multipliers weights the signal in the frequency domain with a reception weight vector. An adder (not shown) is also provided, and the adder adds the outputs of the multiple multipliers. Here, since the signals in the frequency domain are arranged in the order of the subcarrier numbers, the multiplication of the reception weight vector in the multiplier corresponds to that. The adding unit adds the multiplication results in units of subcarriers. As a result, the added signals are also serially arranged in the order of subcarrier numbers as shown in FIG. The added signal is the frequency domain signal 202 described above.

  Also in the following description, when the signal to be processed corresponds to the frequency domain, the processing is basically executed in units of subcarriers. Here, in order to simplify the description, the processing in one subcarrier will be described. Therefore, processing for a plurality of subcarriers can be handled by executing processing on one subcarrier in parallel or serially.

  The synthesizer 54 derives a reception weight vector based on the frequency domain signal, the frequency domain signal 202, and the reference signal from the FFT unit 50. Here, the synthesizer 54 stores a training signal as a reference signal. In the data period, the frequency domain signal 202 is determined based on a predetermined threshold value, and the result is used as a reference signal. The determination may be a soft determination instead of a hard determination. The method for deriving the reception weight vector may be any method, one of which is the derivation by the LMS (Least Mean Square) algorithm. Further, the synthesizer 54 derives a reception response vector that is a transmission path characteristic by correlation processing. Since this is a known technique, a description thereof will be omitted. In order to use the derived reception response vectors in calibration, the control unit 30 (not shown) collects the received response vectors together with the reception response vectors derived in the other synthesis unit 54 in the form of a matrix. This corresponds to the aforementioned H matrix. It is assumed that such a function for deriving the H matrix is also provided in the terminal device 90.

  The space dispersion unit 56 performs beam forming during communication. On the other hand, at the time of calibration, the spatial dispersion unit 56 multiplies the training signal and the data by the steering matrix Q (1), respectively. As a result, a training signal multiplied by the steering matrix Q (1) and data obtained by increasing the number up to the number of training signals are generated. Here, the spatial distribution unit 56 extends the order of the input data to the number of training signals before performing multiplication. The number of input data is “2”, which is represented by “Nin” here. Therefore, the input data is indicated by a vector “Nin × 1”. Further, the number of training signals is “4”, and is represented by “Nout” here. The spatial distribution unit 56 extends the order of the input data from Nin to Nout. That is, the vector “Nin × 1” is expanded to the vector “Nout × 1”. At that time, “0” is inserted into the components from the Nin + 1 line to the Nout line.

ステアリング行列は、「Ｎｏｕｔ×Ｎｏｕｔ」の行列である。また、Ｆ（１）は、直交行列のひとつのフーリエ行列であり、「Ｎｏｕｔ×Ｎｏｕｔ」の行列である。直交行列は、フーリエ行列でなく、ウォルシュ行列であってもよい。なお、ステアリング行列Ｑ（１）による乗算は、サブキャリアを単位にして実行される。さらに、Ｗ（１）は、前述のＣＤＤ行列に相当し、以下のように示される。

The steering matrix Q (1) is shown as follows.

The steering matrix is a “Nout × Nout” matrix. F (1) is one Fourier matrix of an orthogonal matrix, and is a “Nout × Nout” matrix. The orthogonal matrix may be a Walsh matrix instead of a Fourier matrix. Note that multiplication by the steering matrix Q (1) is executed in units of subcarriers. Further, W (1) corresponds to the above-mentioned CDD matrix and is expressed as follows.

  Here, δ represents the shift amount. From the above description, it can be said that the steering matrix Q (1) has been subjected to a cyclic time shift with a row of the orthogonal matrix as one unit. Further, the steering matrix defined in the spatial dispersion unit 56 is the above-described Q (1), and the steering matrix defined in the terminal device 90 (not shown) is the above-described Q (2). As described above, Q (2) may be a unit matrix.

  At the time of communication, the space dispersion unit 56 performs beam forming. The spatial dispersion unit 56 estimates a transmission weight vector necessary for beam forming from the reception weight vector. The method for estimating the transmission weight vector is arbitrary, but as the simplest method, the reception weight vector may be used as it is. Alternatively, the reception weight vector may be corrected by a conventional technique in consideration of the Doppler frequency fluctuation of the propagation environment caused by the time difference between the reception process and the transmission process. Alternatively, transmission beam forming using singular value decomposition may be performed. This can be said to be eigenmode transmission. Here, the received transmission response vector derived by the combining unit 54 is multiplied by the calibration coefficient for the terminal device 90 to obtain the corrected transmission path characteristic, and the transmission weight vector is derived from the corrected transmission path characteristic. Note that the calibration coefficient for the terminal device 90 is acquired from the control unit 30 (not shown). In addition, the calibration coefficient for the terminal device 90 has different values in units of antennas, and further has different values in units of subcarriers.

  The spatial dispersion unit 56 weights the signal with the transmission weight vector. The transmission side correction unit 62 multiplies the signal from the spatial dispersion unit 56 by the calibration coefficient in the base station apparatus 10. At that time, the transmission side correction unit 62 acquires a calibration coefficient for the base station apparatus 10 from the control unit 30 (not shown). The IFFT unit 64 performs inverse Fourier transform on the signal from the transmission side correction unit 62 to convert it into a time domain signal. In FIG. 6, the first time domain signal 200a and the like are shown in two places. These are signals in one direction, and these correspond to the first time domain signal 200a and the like which are bidirectional signals in FIG.

  FIGS. 7A and 7B show signal formats in the communication system 100. FIG. FIG. 7A shows a format in a sequence input to the spatial distribution unit 56. The top row in the figure shows the first series, and the second series, the third series, and the fourth series are shown as the lower stage moves. Here, “4” Long Training Sequences (LTS) are added to each of the “4” sequences that are a plurality of sequences. On the other hand, data of “2” series, which is at least one of a plurality of series, is added as “first data” and “second data”. Here, “LTS” is a signal used for estimating transmission path characteristics. “LTS” corresponds to a training signal. In addition, other signals other than these, for example, “STS (Short Training Sequence)” to be used for timing synchronization or the like are also arranged, but are omitted here.

  FIG. 7B shows a plurality of sequences output from the spatial dispersion unit 56 when calibration is executed. The LTS in FIG. 7A is “LTS ′” as a result of the multiplication of the steering matrix. In FIG. 7B, this is shown as “first LTS ′” to “fourth LTS ′”. The “first data” and “second data” in FIG. 7A are four series of data as a result of the multiplication of the steering matrix. In FIG. 7B, this is shown as “first data” to “fourth data”.

  The calibration operation with the above configuration will be described. Here, the response on the transmitting side of the base station device 10 is indicated as A (1), the response on the receiving side of the base station device 10 is indicated as B (1), and the response on the transmitting side of the terminal device 90 is indicated by A ( 2), and the response on the receiving side of the terminal device 90 is indicated as B (2). A and B are diagonal matrices. Further, the H matrix derived in the terminal device 90 is denoted as H (1 → 2) ′, and the H matrix derived in the base station device 10 is denoted as H (2 → 1) ′. On the other hand, the H matrix reflecting only the radio transmission characteristics is indicated as H (1 → 2) and H (2 → 1) corresponding to the above.

基地局装置１０は、以上のＨ行列を次のように変形させる。

なお、α、β、ｈは、Ａ、Ｂ、Ｈに含まれる成分である。また、基地局装置１０によって導出されるＨ行列は、次のように示される。

First, an operation for the base station apparatus 10 to derive the calibration coefficient C _AUTO (1) for the base station apparatus 10 will be described. At that time, the base station apparatus 10 transmits a training signal to the terminal apparatus 90, but the terminal apparatus 90 transmits a signal from one antenna 14 to the base station apparatus 10. The H matrix derived by the terminal device 90 is shown as follows.

The base station apparatus 10 transforms the above H matrix as follows.

Α, β, and h are components included in A, B, and H. Further, the H matrix derived by the base station apparatus 10 is shown as follows.

このようなキャリブレーション係数Ｃ_ＡＵＴＯ（１）によれば、γ（１）をスカラー量として、次のような関係が成立する。

From these, the calibration coefficient C _AUTO (1) is expressed as follows.

According to such a calibration coefficient C _AUTO (1), the following relationship is established with γ (1) as a scalar quantity.

また、基地局装置１０によって導出されるＨ行列は、次のように示される。

Next, an operation for the base station apparatus 10 to derive the calibration coefficient C _Cross (2) for the terminal apparatus 90 will be described. Before describing the method for deriving the calibration coefficient C _Cross (2) according to the present embodiment, a method for deriving the calibration coefficient C _Cross (2) without using the steering matrix Q (2) will be described. A case where the calibration coefficient C _Cross (2) cannot be derived by such a derivation method will be described. The base station device 10 and the terminal device 90 transmit training signals to each other. Further, it is assumed that the calibration coefficient C _AUTO (1) has already been derived. The H matrix derived by the terminal device 90 is shown as follows.

Further, the H matrix derived by the base station apparatus 10 is shown as follows.

ＡやＢは、対角化行列であるので、基地局装置１０は、Ｈ行列を以下のように変形する。

Here, assuming TDD (Time Division Duplex) and assuming that the uplink and downlink are targets, the following is shown.

Since A and B are diagonal matrices, the base station apparatus 10 modifies the H matrix as follows.

これを利用すると以下の関係が成立するので、Ｃ_{Ｃｒｏｓｓ}（２）はキャリブレーション係数の機能を有する。

すなわち、ステアリング行列Ｑ（１）の逆行列とＨ（１→２）’とを乗算し、乗算した結果の転置行列とＨ（２→１）’の逆行列とを乗算することによって、Ｃ_{Ｃｒｏｓｓ}（２）が導出される。 From these, the calibration coefficient C _Cross (2) is expressed as follows.

When this is utilized, the following relationship is established, so C _Cross (2) has a function of a calibration coefficient.

That is, by multiplying the inverse matrix of the steering matrix Q (1) by H (1 → 2) ′ and multiplying the transposed matrix obtained by the multiplication with the inverse matrix of H (2 → 1) ′, C _Cross (2) is derived.

そのため、次の関係が成立する。

また、Ｂ（１）は対角行列なので、次の関係が成立する。

A case where the calibration coefficient C _Cross (2) cannot be derived by the above derivation method will be described. Although overlapping with the description so far, the calibration coefficient C _Cross (2) for the terminal device 90 is expressed as follows.

Therefore, the following relationship is established.

Since B (1) is a diagonal matrix, the following relationship is established.

すなわち、Ｈ行列の行の数がＨ行列の列の数より少なく、あるいはＨ行列のランク数がＨ行列の列の数と等しくない場合、以上の導出方法は、端末装置９０に対するキャリブレーション係数Ｃ_{Ｃｒｏｓｓ}（２）を導出できない。これは、基地局装置１０でのアンテナ１２の本数が、端末装置９０でのアンテナ１４の本数より少ない場合、あるいはＨ行列のランク数が端末装置９０でのアンテナ１４の本数より少ない場合に対応する。 The following relationship always holds between the calibration coefficient C _Cross (2) for the terminal device 90 and A (2), B (2), and Q (2).

That is, when the number of rows of the H matrix is smaller than the number of columns of the H matrix, or the rank number of the H matrix is not equal to the number of columns of the H matrix, the above derivation method is performed by the calibration coefficient C for the terminal device 90. _Cross (2) cannot be derived. This corresponds to the case where the number of antennas 12 in the base station apparatus 10 is smaller than the number of antennas 14 in the terminal apparatus 90, or the number of ranks of the H matrix is smaller than the number of antennas 14 in the terminal apparatus 90. .

したがって、以下のように示されるキャリブレーション係数Ｃ_{Ｃｒｏｓｓ}（２）を導出すればよいことになる。

行列の演算によって、以下のように示される。

キャリブレーション係数Ｃ_{Ｃｒｏｓｓ}（２）は、以下のように示される。

A process when the steering matrix Q (2) is recognized as a unit matrix or a product of an orthogonal matrix and a CDD matrix will be described. First, processing when the control unit 30 recognizes that the steering matrix Q (2) is a unit matrix will be described. Since the steering matrix Q (2) is a unit matrix, the following relationship is established.

Therefore, a calibration coefficient C _Cross (2) expressed as follows may be derived.

It is shown as follows by the calculation of the matrix.

The calibration coefficient C _Cross (2) is expressed as follows.

  When the steering matrix Q (2) is a unit matrix, the control unit 30 multiplies the inverse matrix of the steering matrix Q (1) by the downlink H matrix. Furthermore, the control unit 30 derives a calibration coefficient for the terminal device 90 by dividing each component of the transposed matrix and the uplink H matrix obtained by multiplication. “Each component” indicates a corresponding element of the transposed matrix and the uplink H matrix. For example, the first row and first column element of the transposed matrix and the first row and first column element of the uplink H matrix.

これは、以下のように展開される。

ここで、Ｆ（２）は、既知であるので、以下のようにＣ_{Ｃｒｏｓｓ}（２）’’を定義する。

Next, processing when the control unit 30 recognizes that the steering matrix Q (2) is a product of an orthogonal matrix and a CDD matrix will be described. Here, as described above, the orthogonal matrix is assumed to be a Fourier matrix. In this case, a calibration coefficient C _Cross (2) shown below may be derived.

This is expanded as follows.

Here, since F (2) is known, C _Cross (2) ″ is defined as follows.

なお、Ａ（２）’は、以下のように示される。

これらより、以下の関係が成立する。

これは、式２０に対応するので、式２２と同様に、Ｃ_{Ｃｒｏｓｓ}（２）’’を導出できる。

最終的に、キャリブレーション係数Ｃ_{Ｃｒｏｓｓ}（２）は、以下のように示される。

Equation 24 is shown as follows.

A (2) ′ is expressed as follows.

From these, the following relationship is established.

Since this corresponds to Equation 20, C _Cross (2) ″ can be derived similarly to Equation 22.

Finally, the calibration coefficient C _Cross (2) is shown as follows:

  When the steering matrix Q (2) is a product of an orthogonal matrix and a CDD matrix, the control unit 30 generates a first multiplication result from the inverse matrix of the steering matrix Q (1) and the downlink H matrix. Further, the control unit 30 generates a second multiplication result from the inverse matrix of the orthogonal matrix and the uplink H matrix. Further, the control unit 30 derives a calibration coefficient for the terminal device 90 (not shown) by dividing the transposed matrix of the first multiplication result and the components of the second multiplication result. In the above processing, the control unit 30 stores the orthogonal matrix in advance in the steering matrix Q (2). That is, the CDD matrix is not used in deriving calibration coefficients. Therefore, even if the value of each element of the CDD matrix is arbitrarily determined in the terminal device 90, this embodiment can cope with it. Further, the value of each element of the CDD matrix should be arbitrarily determined according to the distance between the antennas 14 in the terminal device 90 and the like.

  The operation of the communication system 100 configured as above will be described. FIG. 8 is a sequence diagram illustrating a calibration procedure in the communication system 100. The base station apparatus 10 transmits a training signal (S10). The terminal device 90 derives an H matrix based on the training signal (S12). The terminal device 90 transmits a training signal, transmits the derived H matrix as data, and also transmits an identification number (S14). The base station apparatus 10 derives an H matrix based on the training signal (S16). The base station apparatus 10 performs calibration using the steering matrix Q (2) specified by the identification number and the H matrix (S18). The base station apparatus 10 stores the calibration result (S20). Moreover, the base station apparatus 10 uses the result of calibration for communication.

  FIG. 9 is a flowchart showing a calibration procedure in the base station apparatus 10. The processing unit 22, the radio unit 20, and the like transmit a training signal (S40). The radio unit 20, the processing unit 22 and the like receive the training signal (S42). The control unit 30 receives the identification number via the wireless unit 20, the processing unit 22, and the like (S44). The processing unit 22 derives transmission path characteristics based on the received training signal, and the control unit 30 derives an H matrix (S46). If the identification number corresponds to the unit matrix (Y in S48), the control unit 30 derives a calibration coefficient by a method corresponding to the unit matrix (S50). On the other hand, if the identification number does not correspond to the unit matrix (N in S48), the control unit 30 derives a calibration coefficient by a method corresponding to the Fourier matrix (S52).

  A modification of the embodiment described above will be described. In the embodiments so far, the base station apparatus 10 uses the information of the steering matrix Q (2) when deriving the calibration coefficient for the terminal apparatus 90. Further, in order to specify the steering matrix Q (2), the base station apparatus 10 receives an identification number corresponding to the steering matrix Q (2) from the terminal apparatus 90. Also in the modified example, the information of the steering matrix Q (2) is used when the calibration coefficient for the terminal device 90 is derived as in the embodiment. However, the control unit 30 specifies the steering matrix Q (2) based on the H matrix. Therefore, the base station apparatus 10 does not accept an identification number.

  A communication system 100 according to a modification is shown by a communication system 100 of the same type as in FIG. Therefore, the description of the same parts as those in the embodiment is omitted. The terminal device 90 derives the downlink H matrix and transmits the derived H matrix to the base station device 10. Base station apparatus 10 derives an uplink H matrix based on the signal received from terminal apparatus 90. In addition, the communication system 100 receives a downlink H matrix from the terminal device 90. The base station apparatus 10 specifies whether the steering matrix Q (2) is a unit matrix based on the uplink H matrix and the downlink H matrix. When the steering matrix Q (2) is a unit matrix, the base station apparatus 10 derives a calibration coefficient for the terminal apparatus 90 by a method corresponding to the unit matrix in the embodiment. On the other hand, when the steering matrix Q (2) is not a unit matrix, the base station apparatus 10 derives a calibration coefficient for the terminal apparatus 90 by a method corresponding to the Fourier matrix in the embodiment.

  A base station apparatus 10 according to a modification is shown by the same type of base station apparatus 10 as that of FIG. Therefore, the description of the same parts as those in the embodiment is omitted. The control unit 30 specifies whether the steering matrix Q (2) is a unit matrix based on the derived uplink H matrix and the received downlink H matrix. When the control unit 30 specifies that the steering matrix Q (2) is a non-unit matrix, the steering matrix Q (2) is assumed to be a product of an orthogonal matrix and a CDD matrix.

In the control unit 30, whether the steering matrix Q (2) is a unit matrix is specified as follows. Here, the transposed matrix for the multiplication result of the inverse matrix of the steering matrix Q (1) and the downlink H matrix is defined as a downlink modified H matrix. The downlink modified H matrix is shown by Equation 21 and is denoted [H _DL ′] ^T. In the following description, it is assumed that the steering matrix Q (2) is a unit matrix. The control unit 30 selects two elements having the same row or column from the uplink H matrix and derives the ratio of the two elements. The uplink H matrix corresponds to H _UL ′ in Equation 20. Therefore, in the uplink H matrix, the two elements having the same row or column are the elements in the first row and the first column and the second row and the first column in the matrix of one item at the bottom of Equation 20. It corresponds to the element of. The element in the first row and first column corresponds to h11α1 (2) β1 (1), and the element in the second row and first column corresponds to h12α1 (2) β2 (1). Note that (1 → 2) is omitted. In order to derive these ratios, the element in the first row and the first column is divided by the second row and the first column. As a result, h11β1 (1) / h12β2 (1) is derived as the ratio of the two elements in the uplink H matrix.

  The control unit 30 selects two elements of the downlink modified H matrix so as to correspond to the two elements of the uplink H matrix. Of the modified H matrix of the downlink, the elements corresponding to the two elements of the H matrix of the uplink are the first row and first column elements and the second row and first column of the lowermost matrix of Equation 21. Corresponds to the element. The element in the first row and first column corresponds to γ (1) h11β1 (2) β1 (1), and the element in the second row and first column corresponds to γ (1) h12β1 (2) β2 (1). Note that (1 → 2) is omitted. In order to derive these ratios, the element in the first row and the first column is divided by the second row and the first column. As a result, h11β1 (1) / h12β2 (1) is derived as the ratio of the two elements in the downlink modified H matrix.

  Further, the control unit 30 compares the ratio of the two elements in the uplink H matrix and the ratio of the two elements in the downlink modified H matrix. In the above example, the ratio of the two elements in the uplink H matrix and the ratio of the two elements in the downlink modified H matrix are both equal to h11β1 (1) / h12β2 (1). On the other hand, when the steering matrix Q (2) is a product of an orthogonal matrix and a CDD matrix, the ratio of the two elements in the uplink H matrix and the ratio of the two elements in the downlink modified H matrix are generally Is not equal to Therefore, in the control unit 30, when the ratio of the two elements in the uplink H matrix is the same as the ratio of the two elements in the downlink modified H matrix, the steering matrix Q (2) is a unit matrix. Identifies it.

  When the steering matrix Q (2) is a unit matrix, the control unit 30 derives a calibration coefficient for the terminal device 90 by a method corresponding to the unit matrix. On the other hand, when the steering matrix Q (2) is not a unit matrix, the control unit 30 derives a calibration coefficient for the terminal device 90 by a method corresponding to the Fourier matrix. Since these descriptions are as described above, the descriptions are omitted.

  FIG. 10 is a sequence diagram showing a calibration procedure in the communication system 100 according to the modification of the present invention. The base station apparatus 10 transmits a training signal (S60). The terminal device 90 derives an H matrix based on the training signal (S62). The terminal device 90 transmits a training signal and transmits the derived H matrix as data (S64). The base station apparatus 10 derives an H matrix based on the training signal (S66). The base station apparatus 10 specifies the steering matrix Q (2) based on the H matrix (S68). The base station apparatus 10 performs calibration using the identified steering matrix Q (2) and H matrix (S70). The base station apparatus 10 stores the calibration result (S72). Moreover, the base station apparatus 10 uses the result of calibration for communication.

  FIG. 11 is a flowchart showing a calibration procedure in the base station apparatus 10. The processing unit 22, the radio unit 20, and the like transmit a training signal (S80). The radio unit 20, the processing unit 22 and the like receive the training signal (S82). The processing unit 22 derives transmission path characteristics based on the received training signal, and the control unit 30 derives an H matrix (S84). The control unit 30 derives the element ratio based on the H matrix (S86). If the element ratio is the same (Y in S88), the control unit 30 derives a calibration coefficient by a method corresponding to the unit matrix (S90). On the other hand, if the ratio of the elements is not the same (N in S88), the control unit 30 derives a calibration coefficient by a method corresponding to the Fourier matrix (S92).

  According to the embodiment of the present invention, since an identification number corresponding to the steering matrix Q (2) is received, it is possible to suppress a decrease in transmission efficiency for notifying the steering matrix Q (2). Further, since the steering matrix Q (2) corresponding to the received identification number is used, the accuracy of calibration for the terminal device can be improved. In addition, since calibration is executed after the steering matrix Q (2) is recognized, the derivation of the calibration coefficient can be ensured. In addition, when it is recognized that the steering matrix Q (2) is a unit matrix, the calibration coefficient is derived by processing corresponding to the unit matrix, so that the accuracy of the calibration coefficient can be improved. Further, when the second steering matrix is recognized as a product of an orthogonal matrix and a CDD matrix, the calibration coefficient is derived by a process corresponding thereto, so that the accuracy of the calibration coefficient can be improved.

  In addition, since it is determined whether the steering matrix Q (2) is a unit matrix based on the two H matrices, it can be recognized that the steering matrix Q (2) is a unit matrix while suppressing a decrease in transmission efficiency. Since the calibration coefficient is derived by processing according to the identity matrix, the accuracy of the calibration coefficient can be improved. Further, since it is specified that the steering matrix Q (2) is a unit matrix based on the two H matrices, no additional information is required, and a decrease in transmission efficiency can be suppressed. Further, when it is recognized that the steering matrix Q (2) is not a unit matrix, the calibration coefficient is derived by processing corresponding thereto, so that the accuracy of the calibration coefficient can be improved.

  In the above, this invention was demonstrated based on the Example. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the combination of each component and each processing process, and such modifications are also within the scope of the present invention. .

  In the embodiment of the present invention, the steering matrix Q (2) in the terminal device 90 is assumed to be a unit matrix or a product of an orthogonal matrix and a CDD matrix. However, the present invention is not limited to this. For example, the steering matrix Q (2) may be a product of an orthogonal matrix and a CDD matrix. That is, the orthogonal matrix portion may be fixed. In that case, the control unit 30 stores the orthogonal matrix as in the embodiment. Further, as in the embodiment, a calibration coefficient for the terminal device 90 may be derived. According to this modification, the present invention can be applied even when the orthogonal matrix portion is fixed. Further, since the calibration coefficient can be derived without recognizing the CDD matrix, the terminal device 90 can arbitrarily set the CDD matrix. In addition, since the calibration coefficient is derived by processing according to the fact that the second steering matrix is a product of the orthogonal matrix and the CDD matrix, the accuracy of the calibration coefficient can be improved. That is, it is only necessary to recognize at least a part of the steering matrix Q (2).

  In the embodiment of the present invention, the control unit 30 specifies whether the steering matrix Q (2) is a unit matrix based on the uplink H matrix and the downlink H matrix. However, the present invention is not limited to this. For example, the control unit 30 specifies whether the steering matrix Q (2) is a product of an orthogonal matrix and a CDD matrix based on the uplink H matrix and the downlink H matrix. May be. In this case, a multiplication result of the inverse matrix of the orthogonal matrix and the uplink H matrix is defined as an uplink modified H matrix. The control unit 30 selects two elements having the same row or column from the uplink modified H matrix and derives the ratio of the elements. Further, the control unit 30 selects two elements of the downlink modified H matrix so as to correspond to the two elements in the uplink modified H matrix, and derives a ratio of the selected two elements.

  Further, the control unit 30 determines that the steering matrix Q (2) is orthogonal when the ratio of the two elements in the uplink modified H matrix is the same as the ratio of the two elements in the downlink modified H matrix. It is specified as a product of a matrix and a CDD matrix. When the steering matrix Q (2) is not a product of an orthogonal matrix and a CDD matrix, the steering matrix Q (2) may be a unit matrix. For the identified steering matrix Q (2), a calibration coefficient may be derived as described in the embodiment. According to this modification, the steering matrix Q (2) can be specified without receiving information regarding the steering matrix (2). That is, it is sufficient that at least a part of the steering matrix Q (2) can be recognized when deriving the calibration coefficient. Note that the case where the steering matrix Q (2) is a unit matrix and the case where the steering matrix Q (2) is a product of an orthogonal matrix and a CDD matrix may be combined. The identification accuracy of the steering matrix Q (2) can be improved.

  In the embodiment of the present invention, the communication system 100 has been described as using the OFDM modulation scheme. However, the present invention is not limited to this, and the communication system 100 may use a single carrier method. According to this modification, the present invention can be applied to various communication systems. That is, any communication system that performs beam forming using a plurality of antennas may be used.

  In the embodiment of the present invention, the base station device 10 derives a calibration coefficient for the terminal device 90. However, the present invention is not limited to this. For example, the terminal device 90 may derive a calibration coefficient for the base station device 10. In that case, the operation of the base station device 10 described in the embodiment is performed by the terminal device 90. According to this modification, the configuration of the base station apparatus 10 can be simplified.

It is a figure which shows the spectrum of the multicarrier signal which concerns on the Example of this invention. It is a figure which shows the structure of the communication system which concerns on the Example of this invention. It is a figure which shows the structure of the base station apparatus of FIG. It is a figure which shows the structure of the signal of the frequency domain in FIG. It is a figure which shows the structure of the data memorize | stored in the memory | storage part of FIG. It is a figure which shows the structure of the process part of FIG. FIGS. 7A to 7B are diagrams showing signal formats in the communication system of FIG. It is a sequence diagram which shows the procedure of the calibration in the communication system of FIG. It is a flowchart which shows the procedure of the calibration in the base station apparatus of FIG. It is a sequence diagram which shows the procedure of the calibration in the communication system which concerns on the modification of this invention. It is a flowchart which shows the procedure of the calibration in the base station apparatus of FIG.

Explanation of symbols

  10 base station devices, 12 antennas, 14 antennas, 20 radio units, 22 processing units, 24 modulation / demodulation units, 26 IF units, 30 control units, 32 storage units, 50 FFT units, 52 reception side correction units, 54 combining units, 56 Spatial dispersion unit, 62 transmission side correction unit, 64 IFFT unit, 90 terminal device, 100 communication system.

Claims (14)

A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A communication unit that performs transmission to a wireless device to be communicated after multiplying by a coefficient, and receives at least one sequence multiplied by a second steering matrix in the wireless device to be communicated;
Through the communication unit, the influence of the transmission function in the communication target wireless device, the second steering matrix, the wireless transmission path characteristic from the communication target wireless device, the influence of the reception function in the communication unit are reflected. The first matrix is derived and the influence of the reception function in the communication target wireless device, the first steering matrix, the wireless transmission characteristic to the communication target wireless device, the influence of the transmission function in the communication unit, A first derivation unit that receives a second matrix reflecting the effect of the held calibration coefficient from the wireless device to be communicated;
Via the communication unit, identification information corresponding to a second steering matrix corresponding to a second steering matrix in the wireless device to be communicated, and corresponding to any one of a plurality of types of second steering matrices A reception unit that receives from a wireless device to be communicated;
A second steering matrix identified based on the identification information received in the reception unit; a first matrix derived in the first derivation unit; a second matrix received in the first derivation unit; A second deriving unit for deriving a calibration coefficient for the wireless device to be communicated from a first steering matrix;
A wireless device comprising: The identification information received in the reception unit indicates that the second steering matrix is a unit matrix,
When the second steering matrix is a unit matrix, the second derivation unit is configured to multiply the inverse matrix of the first steering matrix by the second matrix, the transposed matrix obtained by the multiplication, and the first matrix. The wireless device according to claim 1, further comprising means for deriving a calibration coefficient for the wireless device to be communicated by dividing components. The identification information received by the reception unit indicates that the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix,
The second derivation unit, when the second steering matrix includes an orthogonal matrix and a matrix for applying an independent time shift to each of the rows of the orthogonal matrix, an inverse matrix of the first steering matrix And means for generating a first multiplication result from the second matrix, means for generating a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix, a transposed matrix of the first multiplication result and a second multiplication The wireless device according to claim 1, further comprising means for deriving a calibration coefficient for the wireless device to be communicated by dividing each component of the result. A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A communication unit that performs transmission to a wireless device to be communicated after multiplying by a coefficient, and receives at least one sequence multiplied by a second steering matrix in the wireless device to be communicated;
Through the communication unit, the influence of the transmission function in the communication target wireless device, the second steering matrix, the wireless transmission path characteristic from the communication target wireless device, the influence of the reception function in the communication unit are reflected. The first matrix is derived and the influence of the reception function in the communication target wireless device, the first steering matrix, the wireless transmission characteristic to the communication target wireless device, the influence of the transmission function in the communication unit, A first derivation unit that receives a second matrix reflecting the effect of the held calibration coefficient from the wireless device to be communicated;
The second steering matrix in the communication unit includes an orthogonal matrix and a matrix for performing an independent time shift for each of the rows of the orthogonal matrix, and stores the orthogonal matrix of the second steering matrix. A storage unit to
Based on the orthogonal matrix stored in the storage unit, the first matrix derived in the first deriving unit, the second matrix received in the first deriving unit, and the first steering matrix in the communication unit, A second deriving unit for deriving a calibration coefficient for the wireless device to be communicated;
A wireless device comprising:   The second deriving unit generates a first multiplication result from the inverse matrix of the first steering matrix and the second matrix, and generates a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix; And means for deriving a calibration coefficient for the wireless device to be communicated by dividing the transposed matrix of the first multiplication result and each component of the second multiplication result. A wireless device according to 1. A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A communication unit that performs transmission to a wireless device to be communicated after multiplying by a coefficient, and receives at least one sequence multiplied by a second steering matrix in the wireless device to be communicated;
Through the communication unit, the influence of the transmission function in the communication target wireless device, the second steering matrix, the wireless transmission path characteristic from the communication target wireless device, the influence of the reception function in the communication unit are reflected. The first matrix is derived and the influence of the reception function in the communication target wireless device, the first steering matrix, the wireless transmission characteristic to the communication target wireless device, the influence of the transmission function in the communication unit, A first derivation unit that receives a second matrix reflecting the effect of the held calibration coefficient from the wireless device to be communicated;
A specifying unit for specifying the format of the second steering matrix based on the first matrix derived in the first deriving unit and the second matrix received in the first deriving unit;
From the second steering matrix specified by the specifying unit, the first matrix derived in the first deriving unit, the second matrix received in the first deriving unit, and the first steering matrix in the communication unit, A second deriving unit for deriving a calibration coefficient for the wireless device to be communicated;
A wireless device comprising:   In the specifying unit, when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is the third matrix, two elements having the same row or column are selected from the first matrix. Means for deriving a ratio of the two elements, means for selecting two elements of the third matrix so as to correspond to the two elements, and deriving a ratio of the selected two elements; 7. A means for identifying that the second steering matrix is a unit matrix when the ratio of the two elements in the matrix is the same as the ratio of the two elements in the third matrix. A wireless device according to 1.   In the specifying unit, when the transposed matrix for the multiplication result of the inverse matrix of the first steering matrix and the second matrix is the third matrix, and the multiplication result of the inverse matrix of the orthogonal matrix and the first matrix is the fourth matrix , Selecting two elements in the fourth matrix having the same row or column and deriving the ratio of the elements, and the ratio of the two elements of the third matrix so as to correspond to the two elements And the second steering matrix is the same if the means for deriving the ratio of the two selected elements, the ratio of the two elements in the fourth matrix, and the ratio of the two elements in the third matrix are the same: The wireless device according to claim 6, further comprising means for specifying that the matrix is a non-unit matrix.   The second deriving unit, when the specifying unit specifies that the second steering matrix is a unit matrix, means for multiplying the inverse matrix of the first steering matrix by the second matrix, and a transposed matrix obtained by the multiplication And a means for deriving a calibration coefficient for the communication target wireless device by dividing each component of the first matrix. When the second steering matrix is specified as a non-unit matrix by the specifying unit, the second steering matrix includes an orthogonal matrix and a matrix for performing an independent time shift on each of the rows of the orthogonal matrix. Including
The second deriving unit generates a first multiplication result from the inverse matrix of the first steering matrix and the second matrix, and generates a second multiplication result from the inverse matrix of the orthogonal matrix and the first matrix; And a means for deriving a calibration coefficient for the wireless device to be communicated by dividing the transposed matrix of the first multiplication result and each component of the second multiplication result. The wireless device according to any one of 9 to 9. A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A first wireless device that transmits a signal generated by multiplying by a coefficient;
A second wireless device for transmitting a signal generated by multiplying at least one sequence to be transmitted by a second steering matrix;
The second wireless device is based on the signal received from the first wireless device, the influence of the transmission function of the first wireless device, the first steering matrix, the wireless transmission characteristics from the first wireless device, and the second wireless device. Corresponding to means for deriving the first matrix reflecting the influence of the reception function of the first and the previously held calibration coefficient, and then transmitting the derived first matrix to the first radio apparatus and the second steering matrix Means for transmitting to the first radio apparatus identification information corresponding to any one of a plurality of types of second steering matrices,
The first wireless device is based on the signal received from the second wireless device, the influence of the transmission function in the second wireless device, the second steering matrix, the wireless transmission path characteristics from the second wireless device, the first From the means for deriving the second matrix reflecting the influence of the reception function in the wireless device, the second steering matrix specified based on the identification information, the first matrix, the second matrix, and the first steering matrix A communication system comprising means for deriving a calibration coefficient for the second radio apparatus. A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A first wireless device that transmits a signal generated by multiplying by a coefficient;
A second wireless device for transmitting a signal generated by multiplying at least one sequence to be transmitted by a second steering matrix;
The second wireless device is based on the signal received from the first wireless device, the influence of the transmission function of the first wireless device, the first steering matrix, the wireless transmission characteristics from the first wireless device, and the second wireless device. Derivation of the first matrix reflecting the influence of the reception function and the calibration coefficient held in advance, and then transmitting the derived first matrix to the first wireless device,
The first wireless device is based on the signal received from the second wireless device, the influence of the transmission function in the second wireless device, the second steering matrix, the wireless transmission path characteristics from the second wireless device, the first Means for deriving a second matrix reflecting the influence of the reception function in the wireless device; means for identifying the format of the second steering matrix based on the received first matrix and the derived second matrix; A communication system, comprising: a specified second steering matrix; a first matrix; a second matrix; and means for deriving a calibration coefficient for the second radio apparatus from the first steering matrix. A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A wireless device that performs transmission to a wireless device to be communicated after multiplying a coefficient and receives at least one sequence multiplied by a second steering matrix in the wireless device to be communicated; A calibration method for deriving a calibration coefficient for an apparatus,
Deriving the first matrix reflecting the influence of the transmission function in the communication target wireless device, the second steering matrix, the characteristics of the wireless transmission path from the communication target wireless device, and the influence of the reception function in the communication device And the influence of the reception function in the wireless device to be communicated, the first steering matrix, the wireless transmission characteristics to the wireless device to be communicated, the influence of the transmission function in the communication device, the influence of the calibration coefficient held in advance Receiving a second matrix in which is reflected from the wireless device to be communicated;
Receiving identification information corresponding to any one of a plurality of types of second steering matrices, which is identification information corresponding to a second steering matrix, from the wireless device to be communicated;
Deriving a calibration coefficient for the wireless device to be communicated from the second steering matrix identified based on the identification information, the first matrix, the second matrix, and the first steering matrix;
A calibration method comprising: A first steering matrix for distributing at least one sequence to be transmitted to a plurality of transmission antennas is defined, and the calibration held in advance after multiplying at least one sequence to be transmitted by the first steering matrix A wireless device that performs transmission to a wireless device to be communicated after multiplying a coefficient and receives at least one sequence multiplied by a second steering matrix in the wireless device to be communicated; A calibration method for deriving a calibration coefficient for an apparatus,
Deriving the first matrix reflecting the influence of the transmission function in the communication target wireless device, the second steering matrix, the characteristics of the wireless transmission path from the communication target wireless device, and the influence of the reception function in the communication device And the influence of the reception function in the wireless device to be communicated, the first steering matrix, the wireless transmission characteristics to the wireless device to be communicated, the influence of the transmission function in the communication device, the influence of the calibration coefficient held in advance Receiving a second matrix in which is reflected from the wireless device to be communicated;
Identifying a format of the second steering matrix based on the first matrix and the second matrix;
Deriving a calibration coefficient for the wireless device to be communicated from the identified second steering matrix, first matrix, second matrix, and first steering matrix;
A calibration method comprising:

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