JP2010035185A - Communication method of multiantenna communication device, and multiantenna communication device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multiantenna communication device for reconciling both of data transmission speed and transmission quality by relatively easy selection procedures. <P>SOLUTION: A personal computer (PC) 1101 presents the number of beams used for transmission of transmission data and a candidate for combination of modulation systems to a user. Encoding/modulation sections 404A, 404B and a vector multiplexing section 406 use the number of beams and the combination of modulation systems selected by the user to modulate transmission data. Radio sections 412_1, 412_2 perform transmission based on the number of beams selected from a multiantenna in the same frequency band. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a communication method and a multi-antenna communication apparatus for a multi-antenna communication apparatus used in, for example, a MIMO (Multiple-Input Multiple-Output) communication system.

  Conventionally, like a MIMO (Multiple-Input Multiple-Output) communication system, different modulation signals are transmitted from a plurality of antennas at the same time on the transmission device side, and the modulation signals mixed on the propagation path are separated on the reception device side. Thus, techniques for increasing the data transmission speed have been proposed.

  A configuration example of this type of communication system is shown in FIG. Multi-antenna transmission apparatus 20 inputs transmission digital signals 1A to 1D of channels A to D to modulation signal generation units 2A to 2D. Each modulation signal generator 1A-1D performs modulation processing such as BPSK (Binariphase Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation) on the transmission signals 1A-1D, Modulated signals 3A to 3D of channels A to D are formed and transmitted to the radio units 4A to 4D. Each of the radio units 4A to 4D performs predetermined radio processing such as frequency conversion on the baseband modulation signals 3A to 3D to form transmission signals 5A to 5D of radio channels A to D, These are sent to the antennas 6A to 6D.

  The multi-antenna reception device 30 receives signals mixed on the propagation path after being transmitted by the multiple antennas 6A to 6D of the multi-antenna transmission device 20. The multi-antenna receiving apparatus 30 receives signals mixed on the propagation path by the antennas 7_1 to 7_4. Reception signals 8_1 to 8_4 received by the antennas 7_1 to 7_4 are input to the radio units 9_1 to 9_4. The radio units 9_1 to 9_4 obtain baseband signals 10_1 to 10_4 from the received signals 8_1 to 8_4 in the radio band by performing predetermined radio processing such as frequency conversion on the received signals 8_1 to 8_4. The data is sent to the separation / demodulation unit 11. The separation / demodulation unit 11 obtains a spatial correlation matrix between the transmission antennas 6A to 6D and the reception antennas 7_1 to 7_4 based on, for example, a known preamble inserted in each of the modulation signals 3A to 3D, and uses an inverse matrix thereof Thus, the signals corresponding to the modulated signals 3A to 3D are separated and extracted, and the signals corresponding to the separated modulated signals 3A to 3D are demodulated, whereby the received digital signals 12A to 12D corresponding to the transmitted digital signals 1A to 1D are obtained. obtain.

  Furthermore, many techniques have been proposed in the past for improving the data transmission rate in such a multi-antenna communication system. For example, Non-Patent Document 1 proposes a technique for improving the data transmission rate by appropriately switching the number of transmission signals and the modulation method in the modulation signal generation units 2A to 2D.

"Transmission characteristics of MIMO-OFDM system when transmission channel is selected" IEICE, IEICE Technical Report RCS-2003-263, January 2004

  However, as in Non-Patent Document 1, when the number of transmission signals and the modulation method are switched, there are problems that the number of transmission method options increases and the selection procedure of the transmission method becomes complicated. For example, each modulation signal generation unit 2A-2D can select one of BPSK, QPSK, or 16QAM, and select one, two, three, or four of the modulation signal generation units 2A-2D Let us consider a case where the number of transmission signals can be selected by operating automatically. In this case, as a matter of course, the data error can be reduced by selecting QPSK rather than 16QAM as the modulation method and BPSK rather than QPSK, and the number of transmission signals is three rather than four and two than three. When one is used rather than two, interference between transmission signals in the propagation path is reduced, so that reception quality can be improved. However, the data transmission rate decreases as the modulation scheme having a smaller modulation multi-level number is selected or the number of transmission signals is reduced.

  That is, when switching the number of transmission signals and the modulation method as in Non-Patent Document 1, in order to improve reception quality while minimizing the decrease in data transmission speed, which modulation method and which transmission signal number The combination must be selected as the best combination, and the selection procedure becomes complicated.

  The present invention has been made in view of the above points, and provides a communication method for a multi-antenna communication apparatus and a multi-antenna communication apparatus that can achieve both data transmission speed and transmission quality with a relatively simple selection procedure. For the purpose.

  In order to solve such a problem, one aspect of the communication method of the multi-antenna communication apparatus of the present invention includes a step of presenting a candidate of a combination of the number of beams and modulation scheme used for transmission of transmission data to the user, and selection by the user And modulating the transmission data using the combination of the number of beams and the modulation method, and performing transmission based on the selected number of beams from a multi-antenna in the same frequency band.

  One aspect of the multi-antenna communication apparatus of the present invention includes a presentation unit that presents a user with a combination of the number of beams and modulation scheme used for transmission of transmission data, and the number of beams and modulation scheme selected by the user. A modulation unit that modulates the transmission data, and a radio unit that transmits the multi-antenna based on the selected number of beams in the same frequency band.

  According to the present invention, it is possible to realize a communication method for a multi-antenna communication apparatus and a multi-antenna communication apparatus that can achieve both data transmission speed and transmission quality with a relatively simple selection procedure.

FIG. 1 is a block diagram showing configurations of a multi-antenna transmission apparatus and a multi-antenna reception apparatus according to Embodiment 1 of the present invention. The figure for demonstrating operation | movement of the multi-antenna transmission apparatus of Embodiment 1. FIG. Diagram showing a method for sharing channel state information between a sender and a receiver Block diagram showing a configuration of a multi-antenna transmission apparatus according to a second embodiment FIG. 3 is a block diagram illustrating a configuration of a multi-antenna reception apparatus according to a second embodiment. The figure which shows the data structure for performing CRC check The figure for demonstrating the ARQ method of Embodiment 2. The figure for demonstrating the ARQ method of Embodiment 2. The figure for demonstrating the ARQ method of Embodiment 2. The figure which shows the modulation system table of Embodiment 3. Block diagram showing a configuration of a multi-antenna transmission apparatus according to Embodiment 3 The figure which shows the setting screen of the modulation system selection method of Embodiment 3. Flowchart illustrating a procedure for determining modulation scheme selection according to the third embodiment Block diagram showing a configuration of a multi-antenna transmission apparatus according to Embodiment 3 FIG. 9 is a block diagram illustrating a configuration of a multi-antenna reception apparatus according to a third embodiment. The figure which shows the example of the table different from the modulation system table of Embodiment 3. Block diagram showing configurations of a multi-antenna transmission apparatus and a multi-antenna reception apparatus that realizes a MIMO multiplexing scheme using an antenna element mode A block diagram showing a configuration of a conventional MIMO communication system

  The inventors of the present invention weight-synthesize a transmission signal of a plurality of channels with weights corresponding to eigenvectors belonging to eigenvalues of a spatial correlation matrix between a plurality of transmitting and receiving antennas, and supply the signals to a plurality of antennas. In a multi-antenna transmission apparatus that forms a transmission beam (that is, a multi-antenna transmission apparatus that transmits a beam using an eigenmode), if the size of the eigenvalue is positively utilized, the data transmission rate can be achieved with a relatively simple selection procedure. Therefore, the present invention has been achieved.

  The essence of the present invention is that when transmitting a transmission signal that requires a higher quality than other signals, the number of transmission beams is reduced and the transmission signal that requires a higher quality belongs to a large eigenvalue. Is preferentially used to form a transmission beam by vector multiplexing.

  First, before specifically describing the embodiment of the present invention, the eigenmode used in the present invention will be briefly described.

  In the MIMO system, when channel state information (CSI) is known not only on the receiving station but also on the transmitting station side, the transmitting station performs vectorization using a channel signature vector of transmission. The signal is transmitted from the transmission array antenna to the receiving station, and the receiving station detects and demodulates the transmission signal using the reception channel signature vector associated with the transmission channel signature vector from the reception signal of the reception array antenna. A communication method can be realized.

  In particular, as a communication mode in which a plurality of channels are configured in a communication space and signals are multiplexed and transmitted at the same time, a channel matrix (a spatial correlation matrix between a plurality of transmitting and receiving antennas, in other words, each antenna element of a transmitting array antenna and a receiving array). There is an eigenmode (eigenmode) using a singular vector or an eigen vector belonging to eigenvalues of a matrix having elements of complex channel coefficients of all or part of the antenna elements of the antenna. In the present embodiment, the singular vector and the eigenvector are collectively referred to as an eigenvector. This eigenmode is a method of using an eigenvector as the channel signature vector described above. Using this eigenmode, each channel multiplexed at the same time in the communication space can be regarded as an independent path.

  The eigenmode is characterized in that the channel capacity of the MIMO system can be maximized, particularly when the radio channel of the MIMO system can be handled as a narrow-band flat fading process. For example, in a radio communication system adopting OFDM, it is common to design such that each OFDM subcarrier is in a flat fading process by inserting a guard interval in order to remove intersymbol interference caused by multipath delay waves. . Therefore, when transmitting an OFDM signal in a MIMO system, it is possible to spatially multiplex and transmit a plurality of signals on each subcarrier, for example, by using an eigenmode.

  Incidentally, as a method for a transmitting station (assuming a base station) to obtain downlink channel state information, in TDD using the same frequency carrier in the uplink and downlink of a radio channel, due to channel duality (reciprocity), It is possible to estimate or measure channel state information at the transmitting station using an uplink from a receiving station (assuming a terminal). On the other hand, in FDD that uses different frequency carriers for uplink and downlink, downlink channel state information is estimated or measured at the receiving station, and the result is reported to the transmitting station. Accurate CSI can be obtained.

  As a communication method using the MIMO system, there are several methods for making the channel state information of the radio channel known only at the receiving station, compared to the eigenmode in which the channel state information of the downlink is known at the transmitting station and the receiving station. Proposed. For example, BLAST is known as a method for spatially multiplexing and transmitting signals, which has the same purpose as the eigenmode. As a method for obtaining the space diversity effect of the antenna, not at the sacrifice of signal multiplicity, that is, to increase the capacity, for example, transmission diversity using a space-time code is known. The eigenmode is a beam space mode in which a signal is vectorized by a transmission array antenna and transmitted, in other words, a signal is mapped to a beam space and then transmitted. On the other hand, BLAST and transmission diversity transmit a signal to an antenna. It can be said that it is an antenna element mode from mapping to an element (antenna element).

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

(Embodiment 1)
FIG. 1 shows configurations of a multi-antenna transmission apparatus and a multi-antenna reception apparatus according to Embodiment 1 of the present invention. In the present embodiment, a case where multi-antenna transmission apparatus 100 is provided in a base station and multi-antenna reception apparatus 200 is provided in a terminal will be described as an example.

  The multi-antenna transmission apparatus 100 and the multi-antenna reception apparatus 200 constitute a MIMO (Multiple-Input Multiple-Output) system and perform channel multiplex communication using a beam space mode typified by an eigenmode.

The multi-antenna transmission apparatus 100 includes a channel analysis unit 107. The channel analysis unit 107 performs channel matrix (spatial correlation matrix) between a plurality of transmission / reception antennas based on channel state information that is an estimation result of a propagation channel between the plurality of transmission / reception antennas of the multi-antenna transmission apparatus 100 and the multi-antenna reception apparatus 200. ) And analyzing the singular values of this channel matrix (SVD (SVD: Singular Value Decomposition)), the eigenvalues of the channel matrix (for example, λ _A , λ _B , λ _C ,..., Λ _X ) Ask. Here, the eigenvalue of this channel matrix also indicates the path gain of the eigenpath (eg, path A, path B, path C,..., Path X) of each channel. Further, the channel analysis unit 107 calculates channel signature vectors (eigenvectors in the case of the present embodiment) of a plurality of transmission channels to configure a multiplexed channel based on the channel state information. The channel analysis unit 107 sends the obtained eigenvalue and channel signature vector (eigenvector) to the control unit 108.

  The control unit 108 serving as a beam control unit forms a control signal 109 for controlling the multiplexed frame generating unit 101, the encoding / modulating units 103A to 103X, and the vector multiplexing unit 105 with reference to the order of the eigenvalues. . In practice, the control unit 108 controls the control signal 109 as a signal for controlling the multi-frame configuration in the multi-frame generation unit 101, and controls the coding rate and modulation method in the encoding / modulation units 103A to 103X. For this purpose, a channel signature vector (eigenvector) used for vector multiplexing is sent to the vector multiplexing section 105.

  Multi-antenna transmission apparatus 100 inputs a transmission digital signal and control signal 109 to multiple frame generation section 101. Based on the control signal 109, the multiplex frame generation unit 101 transmits a channel A transmission digital signal 102A, a channel B transmission digital signal 102B,..., A channel X as a plurality of transmission frames for mapping to the multiplexed channel. A transmission digital signal 102X is formed and transmitted to the encoding / modulating units 103A to 103X.

  Each coding / modulation section 103A to 103X determines a coding rate and a modulation scheme based on the control signal 109, and performs coding and modulation with the coding rate and the modulation scheme, thereby performing a baseband signal for channel A. The baseband signal 104X of 104A to channel X is obtained and sent to the vector multiplexing unit 105.

  Based on the control signal 109, the vector multiplexing unit 105 multiplies the baseband signals 104A to 104X and adds the channel signature vectors individually to the baseband signals 104A to 104X of the channels A to X, thereby vector-multiplexing the baseband signals 104A to 104X. The multiplexed signal is supplied to the transmission array antenna 106. In other words, the vector multiplexing unit 105 vector-multiplexes the transmission signals of a plurality of channels using eigenvectors belonging to the eigenvalues of the spatial correlation matrix between the plurality of transmission / reception antennas, and supplies the signals to the plurality of antennas. (Eigenpath signal) is formed.

  In this way, the multi-antenna transmission apparatus 100 performs transmission in the eigenmode to the multi-antenna reception apparatus 200.

  Next, the configuration of multi-antenna reception apparatus 200 will be described. The multi-antenna receiving apparatus 200 has a channel analysis unit 208. The channel analysis unit 208 calculates a plurality of channel signature vectors 209 in order to separate multiplexed transmission signals based on channel state information that is an estimation result of propagation channels between a plurality of transmission / reception antennas, and multiplexes them. The signal is sent to the signal separation unit 202.

  Multiplex separation section 202 multiplies each received signal received by receiving array antenna 201 by each channel signature vector to obtain received signals 203A to 203X for channels A to X, and decodes them 204A. To 204X.

  Each of the decoding units 204A to 204X decodes the received signals 203A to 203X of the channels A to X based on the transmission method information (modulation scheme and coding rate information) 211, so that the digital signals of the channels A to X are obtained. 205A to 205X are obtained and sent to the reception data synthesis unit 206.

  Here, transmission method information 211 is extracted from channel A digital signal 205 A by transmission method information detection section 210. The transmission method information 211 includes information on multiple frames in addition to the modulation scheme and coding rate information.

  The reception data combining unit 206 receives the digital signals 205A to 205X and the transmission method information 211 of the channels A to X, and combines the digital signals 205A to 205X based on the transmission method information (multiplex frame information) 211. A received digital signal is obtained.

  In addition to such a configuration, the multi-antenna transmission apparatus 100 performs vector multiplexing on signals that require higher quality than other signals by preferentially using eigenvectors belonging to large eigenvalues. This makes it possible to increase the characteristic path (also referred to as a transmission beam) of a signal that requires high quality, so that the transmission quality of this signal can be improved. Incidentally, the amplitude gain (path gain) of the eigenpath having the eigenvalue λ is √λ.

  Furthermore, the multi-antenna transmission apparatus 100 is configured not to transmit other signals during a time during which a signal requiring higher quality than other signals is transmitted. In other words, during the time when a signal requiring high quality is transmitted through a unique path with a large path gain, another signal is not transmitted through another unique path. As a result, there is no interference between eigenpaths, and the transmission quality of signals that require high quality can be further improved.

  That is, in multi-antenna transmission apparatus 100 of the present embodiment, when transmitting a transmission signal that requires higher quality than other signals, the number of transmission beams is reduced (the number of eigenpaths used for transmission is reduced). The transmission signal is vector-multiplexed using the eigenvector belonging to a large eigenvalue preferentially to form a transmission beam (that is, a signal requiring high quality is preferentially transmitted on an eigenpath having a large path gain). Thus, it is possible to improve the transmission quality of signals that require high quality.

  The operation of the multi-antenna transmission apparatus 100 will be specifically described with reference to FIG. In the present embodiment, a transmission signal that requires higher quality than other signals is assumed to be a preamble and a control information symbol. In other words, the preamble is used on the receiving side to estimate propagation path fluctuation and time-dependent transmission path fluctuations and frequency offset fluctuations, and the control information symbols are transmitted and received on the receiving side such as modulation scheme, coding rate, and data transmission amount. Since these signals are important signals for establishing communication because they are used to notify control information related to the protocol between machines, it is necessary to accurately transmit them with higher quality than other signals such as data symbols. There is.

  FIG. 2 shows a frame configuration of a signal transmitted from multi-antenna transmission apparatus 100 (hereinafter also referred to as a base station). In FIG. 2, reference numeral 201 denotes a preamble, and the multi-antenna receiving apparatus 200 (hereinafter also referred to as a terminal) uses this preamble to detect a signal, estimate a frequency offset, and the like. Reference numeral 202 denotes a control information symbol, and the base station transmits information such as a modulation scheme of each channel, a coding rate, and a transmission amount of data to be transmitted to the terminal using this symbol. Reference numeral 203 denotes a data symbol. Reference numeral 204 denotes a pilot symbol, which is a known symbol, and the terminal uses this symbol to estimate the influence (channel fluctuation) of the data symbol due to channel distortion.

Here, it is assumed in the present embodiment, the eigenvalues _{λ A, λ B, λ C} , ···, and lambda _X was in a relationship of _{λ A> λ B> λ C} >···> λ X. At this time, multi-antenna transmission apparatus 100, as shown in FIG. 2 (A), and transmits the preamble 201, the control information symbol 202 in eigenpath maximum eigenvalue lambda _A is obtained (corresponding to path A, i.e. channel A). In addition, as shown in FIGS. 2B and 2C, signals are not transmitted on the remaining unique paths (corresponding to paths B to X, that is, channels B to X).

  As described above, the preamble 201 and the control information symbol 202 for which high transmission quality is required are transmitted on the eigenpath with the highest path gain and are not transmitted on the other eigenpaths. Will be able to transmit high quality.

  Incidentally, since the signal is transmitted only from the channel A during the period of time 0 to 4 in FIG. 2 and the signal is not transmitted through the other channels B to X during this period, the data transmission amount is reduced by that amount. Since the number of symbols 201 and control information symbols 202 is very small compared to the number of data symbols, the data transmission rate is only slightly reduced. Considering the final data transmission rate, the system can transmit the preamble 201 and the control information symbol 202 at a higher quality than the reduction in transmission rate due to the provision of a period during which only the preamble 201 and the control information symbol 202 are transmitted. The effect of improving the transmission speed by stabilization becomes larger.

Furthermore, in the present embodiment, as can be seen from FIG. 2, data of a channel having a larger eigenvalue is modulated by a modulation scheme having a larger number of modulation multi-values. In the case of FIG. 2, since the eigenvalue λ _A of channel A is larger than the eigenvalue λ _{B of} channel B, the data of channel B is modulated by QPSK, whereas the data of channel A is modulated more than that. Modulation is performed with 16QAM having a large multivalued number. As a result, more data can be obtained without deteriorating the error rate characteristics. That is, since the channel A is transmitted at a greater eigenpath eigenvalue lambda _A is an error even by increasing the number of modulation levels is difficult to occur. Therefore, for channel A, high-speed data transmission is performed using a modulation scheme with a large modulation multi-level number. On the other hand, since channel B is transmitted through an eigenpath having a smaller eigenvalue λ _B than channel A, there is a possibility that the error rate characteristics using the same modulation multilevel modulation scheme as channel A may deteriorate. Therefore, for channel B, a modulation scheme having a smaller modulation multi-value number than channel A is used. As a result, both high-speed data transmission and high-quality transmission can be achieved.

  Thus, according to the present embodiment, when transmitting a transmission signal that requires higher quality than other signals, the number of transmission beams is reduced (that is, the number of unique paths used for transmission is reduced) and the transmission is performed. The signal is vector-multiplexed using preferentially the eigenvector belonging to a large eigenvalue to form a transmission beam (that is, a signal requiring high quality is preferentially transmitted on an eigenpath having a large path gain), The multi-antenna transmission apparatus 100 that can achieve both the data transmission rate and the transmission quality can be realized by a relatively simple selection procedure.

  Also, by making the modulation multi-level number of data transmitted on the eigenpath with a large eigenvalue larger than the modulation multi-level number of data transmitted on the eigenpath with a small eigenvalue, the data transmission speed and the transmission quality are further improved. Will be able to.

  In the present embodiment, the case where the present invention is applied to single carrier communication has been described. However, the present invention is not limited to this, and the same effect can be obtained even when applied to OFDM or a spread spectrum communication system.

  Finally, for reference, one method for sharing channel state information between the multi-antenna transmission apparatus 100 and the multi-antenna reception apparatus 200 will be described with reference to FIG.

<1> First, the terminal makes a communication request to the base station.
<2> Next, the base station requests the terminal to transmit a training symbol (for example, a known signal) for estimating channel information.
<3> The terminal transmits a training symbol.
<4> The base station estimates the channel state from the training symbols transmitted by the terminal.
<5> The base station transmits information on the estimated channel state to the terminal.
<6> The terminal sends a notification that the channel state information has been acquired and a request for data transmission to the base station.
<7> The base station determines the modulation scheme and coding rate of each beam (each channel), and transmits data to the terminal.

  By adopting the method as described above, the base station and the terminal can share the channel state information.

(Embodiment 2)
In this embodiment, a retransmission method capable of achieving both a data transmission rate and transmission quality with a relatively simple procedure will be described.

  The feature of this embodiment is that, when a retransmission signal is transmitted, the number of transmission beams is reduced compared to the previous transmission (that is, the number of eigenpaths used for transmission is reduced), and the retransmission signal is set to a larger eigenvalue than the previous transmission. The transmission beam is formed by vector multiplexing using the belonging eigenvector (transmitting with an eigenpath having a larger path gain than the previous one).

  FIG. 4 shows the configuration of the multi-antenna transmission apparatus of this embodiment. FIG. 5 shows the configuration of the multi-antenna reception apparatus of this embodiment. In this embodiment, a case where multi-antenna transmission apparatus 400 is provided in a base station and multi-antenna reception apparatus 500 is provided in a terminal will be described as an example. Therefore, in the following description, multi-antenna transmission apparatus 400 may be referred to as a base station, and multi-antenna reception apparatus 500 may be referred to as a terminal.

  Multi-antenna transmission apparatus 400 inputs channel state information to channel analysis section 420 via reception antenna 418 and reception section 419. Also, an ACK (Acknowledge) / NACK (Negative Acknowledge) signal 415 from the terminal is input to the frame configuration unit 416 via the reception antenna 418 and the reception unit 419.

  Incidentally, the receiving unit 419 estimates the channel state based on the training symbols transmitted by the terminal and outputs the estimation result as channel state information, as described with reference to FIG.

  The channel analysis unit 420 is configured to determine a channel matrix (spatial correlation matrix) between a plurality of transmission / reception antennas based on channel state information that is an estimation result of a propagation channel between the plurality of transmission / reception antennas of the multi-antenna transmission apparatus 400 and the multi-antenna reception apparatus 500. ) And the eigenvalues of the channel matrix are obtained by analyzing the singular values of the channel matrix. In addition, channel analysis section 420 calculates channel signature vectors (eigenvectors in the case of the present embodiment) of a plurality of transmission channels to configure a multiplexed channel based on the channel state information. The channel analysis unit 420 sends the obtained eigenvalue and channel signature vector (eigenvector) to the control unit 421.

  The control unit 421 serving as a beam control unit forms a control signal 422 for controlling the vector multiplexing unit 406 with reference to the order of the eigenvalue magnitudes. Actually, the control unit 421 transmits a channel signature vector (eigenvector) used for vector multiplexing as the control signal 422.

  The frame configuration signal generation unit 416 generates a frame configuration signal 417 for controlling the frame configuration based on information of an ACK (Acknowledge) / NACK (Negative Acknowledge) signal 415 transmitted by the terminal, and encodes / modulates this It is sent to the sections 404A and 404B. The frame configuration will be described later in detail with reference to FIG.

  Multi-antenna transmission apparatus 400 inputs channel A transmission digital signal 401A and channel B transmission digital signal 401B to encoding / modulation sections 404A and 404B and storage sections 402A and 402B, respectively. The storage units 402A and 402B send the stored transmission digital signals 403A and 403B to the encoding / modulation units 404A and 404B. Transmission digital signals 403A and 403B stored in storage units 402A and 402B are used as retransmission signals.

  Encoding / modulating section 404A receives channel A digital signal 401A, stored channel A digital signal 403A, and frame configuration signal 417, and in accordance with frame configuration signal 417, channel A digital signal 401A or stored channel One of the A digital signals 403 A is encoded and modulated, and the resulting modulated signal 405 A of channel A is sent to the vector multiplexing unit 406. Similarly, encoding / modulation section 404B receives channel B digital signal 401B, stored channel B digital signal 403B, and frame configuration signal 417 as input, and in accordance with frame configuration signal 417, channel B digital signal 401B or storage One of the channel B digital signals 403B thus encoded is encoded and modulated, and the resulting channel B modulation signal 405B is sent to the vector multiplexing unit 406.

  Based on the control information 422, the vector multiplexing unit 406 multiplies the modulation signals 405A and 405B by the channel signature vector and adds them to the channel A and B modulation signals 405A and 405B, and performs modulation after vector multiplexing. Signals # 1 (407_1) and # 2 (407_2) are output.

  Modulated signals # 1 (407_1) and # 2 (407_2) after vector multiplexing are serial / parallel converted by serial / parallel converters (S / P) 408_1 and 408_2 to become parallel signals 409_1 and 409_2, respectively, and inverse Fourier transform units (Ift) Inverse Fourier transform is performed by 410_1 and 410_2 to be OFDM signals 411_1 and 411_2. The OFDM signals 411_1 and 411_2 are converted into transmission signals # 1 (413_1) and # 2 (413_2) by performing predetermined radio processing such as frequency conversion by the radio units 412_1 and 412_2, and the transmission signals # 1 (413_1) are transmitted. ), # 2 (413_2) is transmitted from the antennas 414_1 and 414_2.

  The multi-antenna receiving apparatus 500 in FIG. 5 inputs the received signals # 1 (502_1) and # 2 (502_2) received by the antennas 501_1 and 501_2 to the radio units 503_1 and 503_2. The radio units 503_1 and 503_2 perform predetermined radio processing such as frequency conversion on the received signals # 1 (502_1) and # 2 (502_2), whereby baseband OFDM signals # 1 (504_1) and # 2 (504_2) is obtained and sent to the Fourier transform units (fft) 505_1 and 505_2.

  The Fourier transform units 505_1 and 505_2 perform Fourier transform on the baseband OFDM signals # 1 (504_1) and # 2 (504_2). The signals # 1 (506_1) and # 2 (506_2) after the Fourier transform are sent to the multiplexed signal demultiplexing unit 509 and the channel state information detection unit 507.

  The channel state information detecting unit 507 detects the channel state information from the base station inserted in the signals # 1 (506_1) and # 2 (506_2) after Fourier transform when the procedure is performed as shown in FIG. Further, a plurality of channel signature vectors 508 are calculated in order to separate the multiplexed transmission signals, and are sent to the multiplexed signal separation unit 509.

  The multiple signal demultiplexing unit 509 multiplies each channel signature vector by the Fourier transformed signals # 1 (506_1) and # 2 (506_2), thereby obtaining the modulated signal 510A for channel A and the modulated signal 510B for channel B. These are sent to decoding sections 515A and 515B, transmission path estimation sections 511A and 511B, and frequency offset estimation sections 513A and 513B. Also, channel A modulation signal 510 A is sent to control information detection section 517.

  Control information detection section 517 detects control information symbol 202 in FIG. 2 from modulated signal 510A of channel A, and sends control information 518 including information such as modulation scheme and coding rate to decoding sections 515A and 515B. .

  Each of the transmission path estimation units 511A and 511B extracts the channel A and B pilot symbols 204 in FIG. 2 from the modulated signals 510A and 510B of the channels A and B, estimates the channel fluctuation of each channel based on the pilot symbols, The estimation result is sent to decoding sections 515A and 515B as channel fluctuation estimation signals 512A and 512B of channels A and B.

  Each frequency offset estimator 513A, 513B extracts the preamble 201 and pilot symbol 204 in FIG. 2 from the modulated signals 510A, 510B of channels A and B, and estimates the frequency offset of each channel based on these signals. The result is sent to decoding sections 515A and 515B as frequency offset estimation signals 514A and 514B. In the case of this embodiment, the frequency offset estimation signals 514A and 514B are also transmitted to the radio units 503_1 and 503_2, and the frequency offset removal is also performed by the radio units 503_1 and 503_2.

  Each decoding unit 515A, 515B removes distortion components from modulated signals 510A, 510B based on channel fluctuation estimated signals 512A, 512B and frequency offset estimated signals 514A, 514B, and then modulates the modulation scheme and coding rate of control information 518. Based on such information, the modulated signals 510A and 510B are demodulated and decoded to obtain digital signals 516A and 516B of channels A and B. Digital signals 516A and 516B of channels A and B are sent to CRC check units 519A and 519B.

  Each CRC check unit 519A, 519B performs a CRC check on the digital signals 516A, 516B. That is, the digital signals 516A and 516B of the channels A and B are each composed of data and parity as shown in FIG. 6, and the CRC check units 519A and 519B check the digital signals thus configured. Thus, it is possible to check whether or not an error has occurred. CRC check sections 519A and 513B output ACK / NACK signals 521A and 521B together with received data 520A and 520B.

  Next, a retransmission operation (ARQ (Automatic Repeat Request)) by multi-antenna transmission apparatus 400 of the present embodiment will be described.

FIG. 7 is a diagram illustrating an example of data exchange between a base station (multi-antenna transmission apparatus 400) and a terminal (multi-antenna reception apparatus 500) for explaining the ARQ method according to the present embodiment. Here, it is assumed as a condition that the eigenvalue λ ₁ of the path # ₁ is larger than the eigenvalue λ _{2 of the} path # 2. Further, the modulation method for data that is not retransmitted is 16QAM when using path # 1, and QPSK when using path # 2.

<1> First, the base station transmits channel A data 1A on path # 1 and channel B data 1B on path # 2.
<2> Since there is an error in the data 1A, the terminal requests the base station to retransmit the data 1A.
<3> The base station transmits data 1A ′ corresponding to retransmission data of data 1A of channel A using path # 1.
<4> The terminal does not request retransmission because there is no error in the data 1A.
<5> The base station transmits channel A data 2A on path # 1 and channel B data 2B on path # 2.
<6> Since there is an error in data 2A and data 2B, the terminal requests the base station to retransmit data 2A and data 2B.
<7><8> The base station uses path # 1 to transmit data 2A ′ corresponding to retransmission data of channel 2 data 2A and data 2B ′ corresponding to retransmission data of data 2B of channel B To do.
<9> The terminal does not request retransmission because there is no error in data 2A and data 2B.
<10> The base station transmits channel A data 3A on path # 1 and channel B data 3B on path # 2.
<11> Since there is an error in the data 3B, the terminal requests the base station to retransmit the data 3B.
<12> The base station transmits data 3B ′ corresponding to retransmission data of channel 3 data 3B using path # 1.

  Note that the retransmission data (for example, data 1A ′) may be the same data as the original data (for example, data 1A), or may be recoverable data (for example, punctured data). .

  The following two points are important in the above processing.

  First, the number of paths is reduced when retransmitting. In the example of FIG. 7, the number of paths is 2 when transmitting data, and the number of paths is 1 when retransmitting. As a result, the number of paths is reduced at the time of retransmission, that is, interference is reduced, so that the data reception quality is improved. As a result, the number of retransmissions can be reduced, and the data throughput can be improved.

  Second, when retransmitting, retransmission data is retransmitted preferentially using a path having a larger eigenvalue than the previous transmission. Considering this in combination with the first point, when reducing the number of paths, it is assumed that a path with a small eigenvalue is preferentially deleted, and retransmission data is retransmitted using a path with a large eigenvalue. I can also say. Thereby, retransmission data is transmitted using a path with a large eigenvalue, that is, a path with a large path gain, so that the data reception quality is improved. As a result, the number of retransmissions can be reduced, and the data throughput can be improved.

  Incidentally, if the modulation method of the original data and the data to be retransmitted is the same, the configuration of the transmission apparatus can be simplified. That is, in FIG. 7, for example, the modulation schemes of data 1A and retransmission data 1A ′ of channel A are the same, and modulation schemes of data 2B and retransmission data 2B ′ are the same in channel B. In this embodiment, at the time of retransmission, the number of paths is reduced, or the retransmission signal is retransmitted on an eigenpath having a larger eigenvalue than at the previous transmission, so it is not necessary to reduce the modulation multilevel number at the time of retransmission. A sufficient improvement in error rate characteristics can be expected. In this way, by making the modulation method of the original data and the data to be retransmitted the same, there is no need to perform encoding or interleaving again in order to generate retransmission data in the transmission device. Can be simplified.

  However, if priority is given to improving the quality of data over simplifying the configuration of the transmitting apparatus, it is better to reduce the number of modulation multi-levels of retransmission data.

  In FIG. 7, the ARQ method of the present invention has been described by taking the case of two transmission antennas as an example, but the ARQ method of the present invention is naturally applicable to the case of three or more transmission antennas. In the following, an ARQ method for transmitting three modulated signals with three transmission antennas will be described with reference to FIGS. 8 and 9 as an example.

First, the exchange of data between the base station and the terminal in FIG. 8 will be described in detail. 8, it is assumed that as a condition, the eigenvalues lambda ₁ passes # 1, the eigenvalues lambda ₂ pass # 2, the eigenvalues lambda ₃ passes # 3, in λ _1> λ _2> λ ₃ relationships. Further, the modulation method for data that is not retransmitted is 16QAM when using path # 1, QPSK when using path # 2, and BPSK when using path # 3.

<1> First, the base station transmits channel A data 1A on path # 1, channel B data 1B on path # 2, and channel C data 1C on path # 3.
<2> Since there is an error in the data 1C, the terminal requests the base station to retransmit the data 1C.
<3> The base station transmits data 1C ′ corresponding to retransmission data of data 1C of channel C using path # 1.
<4> The terminal does not request retransmission because there is no error in the data 1C.
<5> The base station transmits channel 2 data 2A on path # 1, channel B data 2B on path # 2, and channel C data 2C on path # 3.
<6> Since there is an error in data 2A and data 2B, the terminal requests the base station to retransmit data 2A and data 2B.
<7><8> The base station uses path # 1 to transmit data 2A ′ corresponding to retransmission data of channel 2 data 2A and data 2B ′ corresponding to retransmission data of data 2B of channel B To do.
<9> The terminal does not request retransmission because there is no error in data 2A and data 2B.
<10> The base station transmits channel 3 data 3A on path # 1, channel B data 3B on path # 2, and channel C data 3C on path # 3.
<11> The terminal requests retransmission of data 3B to the base station because there is an error in data 3B.
<12> The base station transmits data 3B ′ corresponding to retransmission data of channel 3 data 3B using path # 1.

Next, the exchange of data between the base station and the terminal in FIG. 9 will be described in detail. In FIG. 9, as in FIG. 8, the conditions are as follows: eigenvalue λ ₁ of path # ₁ , eigenvalue λ ₂ of path # ₂ , and eigenvalue λ ₃ of path # 3 satisfy λ ₁ > λ ₂ > λ ₃ . Suppose that Further, the modulation method for data that is not retransmitted is 16QAM when using path # 1, QPSK when using path # 2, and BPSK when using path # 3.

<1> First, the base station transmits channel A data 1A on path # 1, channel B data 1B on path # 2, and channel C data 1C on path # 3.
<2> Since there is an error in data 1A, data 1B, and data 1C, the terminal requests the base station to retransmit data 1A, data 1B, and data 1C.
<3> The base station first uses the path # 1 to correspond to the data 1B ′ corresponding to the retransmission data of the data 1B of the channel B, and corresponds to the retransmission data of the data 1C of the channel C using the path # 2. Data 1C ′ is transmitted. Next, the base station transmits data 1A ′ corresponding to retransmission data of data 1A of channel A using path # 1. At this time, in the path 2 #, there is no other modulation signal.
<4> The terminal does not request retransmission because there is no error in the data 1A, 1B, 1C.
<5> The base station transmits channel 2 data 2A on path # 1, channel B data 2B on path # 2, and channel C data 2C on path # 3.
<6> Since there is an error in data 2B and data 2C, the terminal requests the base station to retransmit data 2B and data 2C.
<7> The base station uses the path # 1 and data 2B ′ corresponding to the retransmission data of the data 2B of the channel B, and data 2C ′ corresponding to the retransmission data of the data 2C of the channel C using the path # 2. Send.
<8> The terminal does not request retransmission because there is no error in data 2B and data 2C.
<9> The base station transmits channel 3 data 3A on path # 1, channel B data 3B on path # 2, and channel C data 3C on path # 3.
<10> Since there is an error in the data 3C, the terminal requests the base station to retransmit the data 3C.
<11> The base station transmits data 3C ′ corresponding to retransmission data of data 3C of channel C using path # 1.

  Here, the feature of the ARQ method described in FIG. 8 is that retransmission data is transmitted using an eigenpath having the largest eigenvalue. In addition, while the retransmission data is being transmitted, the signal is not transmitted on another unique path. As a result, the quality of retransmission data can be improved compared to when data is transmitted (that is, during normal transmission), and therefore the number of retransmissions can be reduced. As a result, the data throughput can be improved.

The features of the ARQ method described in FIG. 9 are as follows.
・ Reduce the number of paths used during retransmission.
• When retransmitting, a path with a large path gain is preferentially used.
-Retransmission of data other than data transmitted through the path with the maximum gain at the previous transmission is performed using a path with a larger path gain than at the previous transmission.
Retransmission of data transmitted through the maximum gain path at the previous transmission is performed independently without using other paths in addition to using the maximum gain path again.

  By doing so, the quality of retransmission data can be improved compared to the previous transmission, and therefore the number of retransmissions can be reduced. As a result, the data throughput can be improved. In addition, since retransmission data is transmitted using a path having a larger path gain than the previous transmission to achieve quality improvement at the time of retransmission, retransmission data is transmitted using a plurality of paths (for example, Compared with <3> and <7> in FIG. 9) and the ARQ method in FIG. 8, there is also an effect that the transmission rate of retransmission data can be increased.

  As described above, according to this embodiment, when transmitting a retransmission signal, the number of transmission beams is reduced (that is, the number of eigenpaths used for transmission is reduced) compared to the previous transmission, and the retransmission signal is transmitted more than the previous transmission. By performing vector multiplexing using eigenvectors belonging to large eigenvalues to form a transmission beam (transmitting with an eigenpath having a larger path gain than the previous one), the number of retransmissions can be reduced with a relatively simple selection procedure. And the data throughput can be increased.

  In the present embodiment, for the sake of convenience, the frame configuration in FIG. 2 has been used for explanation, but since this embodiment is an example using the OFDM scheme, the symbol in FIG. 2 is a symbol composed of a plurality of subcarriers. It shall be equivalent to

  In this embodiment, the case where the present invention is applied to the OFDM system has been described as an example. However, the present invention is not limited to this, and the same effect can be obtained when the present invention is applied to a spread spectrum communication system or a single carrier system. be able to.

  In this embodiment, how to share channel state information is not described in detail, but sharing of channel state information may or may not be performed at the time of retransmission. That is, the method of sharing channel state information does not affect the characteristics of the present embodiment.

  Furthermore, in the present embodiment, the modulation method is particularly described as a transmission method parameter, but retransmission may also be performed in consideration of parameters such as an encoding method and an encoding rate. Even when is added, the present invention can be similarly implemented.

(Embodiment 3)
In the present embodiment, a description will be given of a method for determining and setting a suitable modulation scheme when performing the transmission method as in the first and second embodiments.

  In the present embodiment, a case where the number of antennas of the base station is 2 and two modulated signals are transmitted will be described as an example.

  Consider a case where a communication method that can be changed among BPSK, QPSK, 16QAM, and 64QAM is adopted as a modulation method. Also, a channel that is transmitted in a path with a large eigenvalue is named channel A, and a channel that is transmitted in a path with a small eigenvalue is named channel B (except when retransmission data is transmitted). At this time, when all combinations of transmission channels and modulation schemes are considered, a modulation scheme setting table as shown in FIG. 10 can be created. 10 is a transmission method supported as a standard.

  By the way, for example, setting # 2 and setting # 5, setting # 3 and setting # 9 in FIG. 10 have the same transmission speed. In this way, if there are two or more types of transmission methods having the same transmission rate, or if the possibility of selecting transmission methods as shown in FIG. 10 is increased (that is, all combinations are prepared), the determination of the transmission method becomes complicated. Challenges arise.

  Therefore, in the present embodiment, a method will be described in which, for example, in a personal computer or the like, the modulation method selection method can be limited to a transmission method that meets the user's request from among the transmission methods supported by the standard.

  FIG. 11 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 4 shows the configuration of the multi-antenna transmission apparatus of this embodiment. The personal computer (PC) 1101 sends transmission method setting information 1102 to the frame configuration signal generation unit 416. The frame configuration signal generation unit 416 limits the transmission method based on the transmission method setting information 1102.

  FIG. 12 shows an example of a transmission method setting screen by the PC 1101. What is particularly important here is that the quality priority mode and the high-speed transmission priority mode can be selected, and the maximum delay time can be set.

  The reason why these are important in the system will be described in detail later.

  Consider a system capable of transmitting 500 kbit / s, for example, by transmitting using BPSK with only one channel. Then, when transmitting 50 kbit data, it is assumed that the environment can transmit data with setting # 14 in FIG. Then, it is assumed that transmission is performed with setting # 14. However, if data is transmitted with setting # 14, the possibility of error is very high, and there is a high possibility of being requested for retransmission, and transmission time due to retransmission is consumed, and transmission is performed with the transmission method of setting # 1 in FIG. As a result, the data transmission time may be shortened.

Such a situation occurs when the amount of data is very small with respect to the data transmission rate. For this problem, it is important to have a function for performing the following settings from the outside (for example, using a PC).
(Method 1) It is possible to set a quality priority mode, a high-speed transmission priority mode, and the like.
(Method 2) It is possible to set a maximum delay time.

  In FIG. 10, data quality is better when only one channel signal is transmitted than when two channel signals are transmitted. Therefore, when a configuration that can be set as in (Method 1) is adopted and the user mainly uses it for the purpose of transmitting data with a small capacity, the quality priority mode is selected and data with a large capacity is transmitted. The above problem can be avoided by selecting the high-speed data transmission mode when mainly using for the purpose. At this time, as shown in FIG. 12, the quality priority mode is a table mainly configured from settings # 1 to # 4, and the high-speed transmission priority mode is a table mainly configured from settings # 5 to # 14. It becomes. In the quality priority mode, a transmission method for transmitting only one channel signal is preferentially assigned.

  At this time, it is the setting of the maximum delay time that plays an important role. The maximum delay time is the maximum delay time allowed by the user. At this time, the transmission method as shown in FIG. 13 is determined.

  First, in step SP1, the time required for transmission in the case of transmission by each transmission method in a table (for example, the table shown in FIG. 12) is calculated from the transmission amount of data to be transmitted.

  Next, in step SP2, it is determined whether there is a transmission method in the table that requires a shorter time for transmission than the maximum delay time.

  If there is no transmission method in the table that requires a shorter transmission time than the maximum delay time, the process proceeds to step SP4 to select a transmission method that achieves both transmission speed and transmission quality from the propagation environment.

  On the other hand, if there is a transmission method in the table in which the time required for transmission is shorter than the maximum delay time, the process proceeds to step SP3, and the reception quality is the highest among the transmission methods having a transmission time shorter than the maximum delay time. Choose a good transmission method.

  As described above, selecting a transmission method based on the maximum delay time eliminates the possibility of selecting a transmission method with an excessive transmission rate when the amount of data is small, thereby stabilizing the data transmission rate and transmission quality. Will be able to build.

  In addition to the quality priority mode and the high-speed transmission priority mode, a learning mode, a user setting mode, and a save mode are proposed as effective modes on the system.

  When there is a learning mode and a user setting mode, the configuration shown in FIG. 14 may be adopted. 14 that operate in the same manner as in FIG. 4 are given the same reference numerals. The personal computer (PC) 1401 of the multi-antenna transmission apparatus 1400 sends mode setting information 1402 to the transmission method setting / learning unit 1403. The transmission method setting / learning unit 1403 is set to the setting mode based on the mode setting information 1402, determines a transmission method from ACK / NACK based on the method of the setting mode, and uses this as transmission method determination information 1404 to construct a frame configuration The signal is sent to the signal generator 416.

  The frame configuration signal generation unit 416 refers to the transmission method determination information 1404 and outputs a frame configuration signal 417 that is information regarding the frame configuration based on the determined transmission method.

  At this time, for example, in the case of a cellular base station, a wireless LAN access point, or the like, if the learning mode setting is created by learning the transmission method table, there is an advantage that the determination of the transmission method can be simplified.

  Cellular base stations and wireless LAN access points rarely move. Therefore, the propagation environment greatly depends on the installation location. Therefore, it is possible to simplify the determination of the transmission method by learning a transmission method having a high possibility of establishing communication and creating a table. Therefore, a method for setting the learning mode is effective.

  In the learning mode, for example, in the table of FIG. 10, in each of the setting # 1 to the setting # 14, for example, statistics of the number of NACKs / number of ACKs are taken and deleted from the transmission method with a high probability of NACK, Limit the types of transmission methods. Thereby, the determination of the transmission method can be simplified. When the location is moved from the PC 1401 or from the outside, resetting and re-learning can learn and re-create a table suitable for the moved location.

  The user setting mode is a method in which the user creates a table by limiting the types of transmission methods. Thereby, the determination of the transmission method can be simplified. Alternatively, a method of downloading, obtaining, and setting the table software from the outside may be used.

  Next, the save mode will be described. In particular, this is a mode for setting the receiving device of the terminal. FIG. 15 in which parts corresponding to those in FIG.

  The multi-antenna receiving apparatus 1500 sets a mode using a personal computer (PC) 1501, and sends this to the control unit 1503 as mode setting information 1502. A control unit 1503 receives mode setting information 1502 and control information 518 including information such as a modulation scheme and a coding rate, is set to a save mode, and the control information 518 is a modulation signal of one channel. When a transmission method that only exists, a control signal 1504 that stops the operation of one of the radio units 503_1 and 503_2 is output.

  Thereby, the power consumption of the receiving device of a terminal can be reduced. Here, the operation of only the radio unit is stopped. However, the present invention is not limited to this, and the same effect can be obtained by stopping the operation of the part that performs digital signal processing.

  As described above, by limiting the transmission method based on information from the outside, and enabling the learning mode and save mode to be set, simplification of the transceiver, low power consumption, data transmission speed and Both reception quality can be achieved. In particular, these effects are significant when a transmission method using MIMO transmission is included.

  Even if the above-described transmission method switching is similarly applied at the time of retransmission, the same effect as described above can be obtained.

  Next, a method of creating a table as shown in FIG. 16 that is different from the table of FIG. 12 will be described. In FIG. 16, the application mode can be set on the screen of the personal computer. For example, the user can select one of the “moving image mode”, “Internet mode”, “file download mode”, “game mode”, “learning mode”, and “user setting mode”. When a mode other than “learning mode” and “user setting mode” is selected, the transmission mode, maximum delay time, and retransmission delay time are automatically set, and “learning mode” and “user setting mode” are selected. Sometimes, the maximum delay time and retransmission delay time can be set by the user. Even when such a table is created and the mode is set using a personal computer, it can be carried out in the same manner as described above, and the same effect can be obtained.

  In this embodiment, the modulation method is particularly described as a transmission method parameter. However, a transmission method table may be created in consideration of parameters such as an encoding method and an encoding rate. Even when these parameters are added, the present invention can be similarly implemented.

  The feature of the present embodiment can be applied not only to the eigenmode MIMO system but also to, for example, a MIMO multiplexing system using an antenna element mode. Hereinafter, for reference, a MIMO multiplexing scheme using the antenna element mode will be described.

  FIG. 17 shows a configuration example of a multi-antenna transmission apparatus and a multi-antenna reception apparatus that realizes a MIMO multiplexing scheme using an antenna element mode.

  The multi-antenna transmission apparatus 1700 inputs the transmission digital signals 1701A, 1701B, and 1701C of channels A, B, and C to the modulation signal generation units 1702A, 1702B, and 1702C, and modulates the channels to generate channels A, B, and C. Modulation signals 1703A, 1703B, and 1703C are obtained. The radio units 1704A, 1704B, and 1704C obtain transmission signals 1705A, 1705B, and 1705C by performing predetermined radio processing such as frequency conversion on the modulated signals 1703A, 1703B, and 1703C of the channels A, B, and C, respectively. This is supplied to the antennas 1706A, 1706B, and 1706C.

  Multi-antenna receiving apparatus 1800 inputs received signals 1708_1, 1708_2, and 1708_3 received by antennas 1707_1, 1707_2, and 1707_3 to radio units 1709_1, 1709_2, and 1709_3. The radio units 1709_1, 1709_2, and 1709_3 perform predetermined radio processing such as frequency conversion on the received signals 1708_1, 1708_2, and 1708_3 to obtain baseband signals 1710_1, 1710_2, and 1710_3, which are separated and demodulated units 1711.

  The separation / demodulation unit 1711 separates the transmitted original modulation signals 1703A, 1703B, and 1703C from the baseband signal 1710_1, the baseband signal 1710_2, and the baseband signal 1710_3, and further demodulates them, thereby performing channel A, B and C received digital signals 1712A, 1712B and 1712C are obtained.

  Here, the modulation signal 1703A of channel A, the modulation signal 1703B of channel B, and the modulation signal 1703C of channel C are Txa (t), Txb (t), and Txc (t), respectively, and a baseband signal 1710_1 and a baseband signal 1710_2. When the baseband signal 1710_3 is Rx1 (t), Rx2 (t), and Rx3 (t), the following relational expression is established. However, h11 (t) to h33 (t) are channel fluctuation values between the transmitting and receiving antennas.

すなわち、分離・復調部１７１１は、（１）式の関係式に基づいて、チャネルＡ、チャネルＢ、チャネルＣの信号を分離する。

That is, the separation / demodulation unit 1711 separates the signals of channel A, channel B, and channel C based on the relational expression (1).

  By the way, each of the modulation signals Txa (t), Txb (t), and Txc (t) can be an independent modulation method. Then, as described in the present embodiment, there are problems that the number of transmission methods increases and the selection method of the transmission method becomes complicated. However, by applying the processing described in the present embodiment to such a MIMO multiplexing scheme, it is possible to simplify the transmission method selection procedure.

  The present invention is suitable for application to a communication method and a multi-antenna communication apparatus of a multi-antenna communication apparatus used in a multi-antenna communication system such as a MIMO system or an OFDM-MIMO system.

100, 400, 1100 Multi-antenna transmitter 101 Multiplex frame generator 103A-103X, 404A, 404B Encoding / modulator 105, 406 Vector multiplexer 106, 201 Array antenna 107 Channel analyzer 108 Controller 200, 500 Multi-antenna Receiving device 202, 509 Multiplex signal demultiplexing section 204A to 204X Decoding section 206 Received data combining section 208 Channel analyzing section 210 Transmission method information detecting section

Claims (6)

Presenting a user with a candidate combination of the number of beams and modulation scheme used for transmission of transmission data;
Modulating the transmission data using a combination of the number of beams and modulation scheme selected by the user;
Transmitting in the same frequency band based on the selected number of beams from multiple antennas;
A communication method for a multi-antenna communication apparatus including: The combination of the number of beams and the modulation scheme is a combination grouped according to error tolerance during reception of the transmission data, or transmission capacity.
The communication method of the multi-antenna communication apparatus according to claim 1. The combination of the number of beams and the modulation scheme is a combination with few retransmission requests among the combinations of the number of beams and the modulation scheme selected previously.
The communication method of the multi-antenna communication apparatus according to claim 1. The combination of the number of beams and the modulation scheme is a combination grouped according to the type of application of the transmission data.
The communication method of the multi-antenna communication apparatus according to claim 1. The combination of the number of beams and the modulation method is a combination in which the time required for transmitting the transmission data is less than a predetermined time.
The communication method of the multi-antenna communication apparatus according to claim 1. A presentation unit for presenting a candidate for a combination of the number of beams and modulation scheme used for transmission of transmission data to the user;
A modulation unit that modulates the transmission data using a combination of the number of beams and modulation scheme selected by the user;
A radio unit for transmitting based on the selected number of beams from multiple antennas in the same frequency band;
A multi-antenna communication apparatus comprising:

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