JP5340344B2 - Communication apparatus and communication method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a communication apparatus and method, capable of transmitting transmission rate request signals by reducing them without practically reducing the efficiency of transmission, thereby reducing interference and power consumption in transmission of transmission rate request signals, in a MIMO communication system. <P>SOLUTION: A modulation coding part 112 performs coding processing and modulating processing of transmission data to be transmitted to a communication partner of a MIMO communication system and transmission rate request signals in the plurality of transmission antennas. A transmitting part 114 and transmitting antennas 116 transmit signals from the modulation coding part 112. A transmission control unit 110 controls transmission of signals transmitted from the transmission antennas 116, and when an absolute value ¾AD-BC¾ of an inverse matrix as a result of an estimated propagation path generated in an interference compensation part 124 using a signal from the communication partner is smaller than a threshold, the transmission control unit transmits transmission rate request signals for one transmission antenna through the transmission antennas 116. <P>COPYRIGHT: (C)2011,JPO&amp;INPIT

Description

  The present invention relates to a communication apparatus and a communication method used in a wireless communication system using MIMO (Multiple Input Multiple Output) technology for performing wireless communication by receiving wireless signals transmitted from a plurality of antennas using a plurality of antennas.

  In recent years, MIMO (Multi-Input / Multi-Output) communication has attracted attention as a technology that enables large-capacity data communication such as images. In MIMO communication, different transmission data (substreams) are transmitted from a plurality of antennas on the transmission side, and on the reception side, a plurality of transmission data mixed on the propagation path are separated into original transmission data using propagation path estimation values. To do.

  In practice, in MIMO communication, a signal transmitted from a transmission apparatus is received by the number of antennas equal to or greater than the number of transmission apparatuses, and the pilot signals respectively inserted in the signals received by the antennas. Based on this, the channel characteristics between the antennas are estimated.

  This estimated propagation path characteristic H is represented by a 2 × 2 matrix when there are two transmitting antennas and two receiving antennas, for example. In MIMO communication, a transmission signal (substream) transmitted from each transmission antenna is obtained based on the inverse matrix of the obtained propagation path characteristic H and the reception signal obtained by each reception antenna.

  The principle of MIMO communication when the number of antennas of the transmitter 10 and the receiver 20 is two will be described with reference to FIG. Here, signals transmitted from the antennas 11 and 12 of the transmitter 10 are TX1 and TX2, respectively, and signals received by the antennas 21 and 22 of the receiver 20 are RX1 and RX2, respectively. At this time, the received signals (RX1, RX2) can be expressed by (Equation 1) shown in FIG.

  In (Equation 1), A is a propagation path characteristic between the transmission antenna 11 and the reception antenna 21, B is a propagation path characteristic between the transmission antenna 12 and the reception antenna 21, and C is a transmission antenna 11 and the reception antenna. The propagation path characteristic between the transmission antenna 12 and the reception antenna 22 is represented by D.

  At this time, for example, when the signal transmitted to the receiver 20 is only TX1, TX2 becomes an interference signal for the receiver 20, and the signal received by the antenna 21 includes the desired signal component and the interference signal component. Both will be included. The same applies to the antenna 22.

  In order to obtain the transmission signals (TX1, TX2) by removing (compensating) the above-described interference signal components from the received signal, the four propagation path characteristics A, B, C, D are obtained as shown in (Equation 2). It is necessary to obtain the inverse matrix of Therefore, the transmitter 10 transmits a signal obtained by inserting a known signal for propagation path estimation (for example, a pilot signal) into the transmission signal, and the receiver 20 performs propagation path estimation based on the known signal, and propagation path characteristics. A, B, C, and D are obtained, and the above inverse matrix is obtained.

  Actually, as a procedure for obtaining the transmission signals (TX1, TX2) from the reception signals (RX1, RX2), ZF (Zero-Forcing) that separates substreams (each data) only by the inverse matrix operation shown in (Equation 2) An arithmetic operation or an MMSE (Minimum Mean Square Error) operation that separates to minimize the error is used.

  In this way, in MIMO communication, a plurality of signals transmitted at the same frequency at the same time can theoretically be separated by the receiver, so that high-speed and large-capacity communication is possible.

  By the way, with respect to the MIMO communication system, on the transmission side, a plurality of transmission systems using a radio unit including a power amplifier with high power consumption are required. For this reason, it is known that in the communication system, when the MIMO communication method is applied to the uplink, the power consumption of the receiver 20 becomes very large. Downlink is regarded as important for the throughput in wireless communication. For these reasons, the MIMO communication system is generally used for the downlink.

  In such a MIMO communication system, as shown in Non-Patent Document 1, in order to further improve the throughput, a transmission rate is set independently for each antenna, and a CQI (Channel Quality) which is a transmission rate setting signal for each antenna. A method of transmitting (Indicator) is being studied.

  The CQI is a signal indicating the modulation method and coding rate of packet data that can be demodulated by the receiver 20, and based on this CQI, the transmitter 10 determines the receiver 20 that is the transmission destination of transmission data, At the same time, an optimum transmission rate is determined and transmission data is transmitted.

  Specifically, the base station has the CQI transmitted from the mobile station (receiver 20) at a period set by a host device such as an RNC (Radio Network Controller). The base station that has received this CQI performs scheduling using the CQI sent from the mobile station and independently selects the optimum modulation scheme, coding rate, etc. for each antenna. Then, the base station modulates and encodes transmission data using the selected modulation scheme and coding rate, and transmits the data to the mobile station based on the scheduling result. As a result, a large amount of data can be transmitted from the base station to the mobile station by adaptively changing the transmission rate according to the radio wave propagation environment.

3GPP TS25.876

  However, in the conventional MIMO communication method in which a transmission rate is set independently for each antenna, a receiver (terminal device) transmits a transmission rate request signal (CQI) corresponding to the number of antennas to a communication partner. For this reason, the transmission rate request signal amount transmitted from the receiver side to the transmission side is multiplied by the number of antennas. Therefore, when transmitting a transmission rate request signal from the receiving side, there are problems that interference with other receivers (users) increases and power consumption of the receivers increases.

  An object of the present invention is to provide a communication apparatus and a communication method capable of reducing transmission rate request signals and transmitting them without substantially reducing transmission efficiency, and reducing interference and power consumption when transmitting transmission rate request signals. Is to provide.

The communication apparatus of the present invention comprises receiving means for receiving a request signal from a communication partner, and transmitting means for transmitting data from a plurality of antennas based on the request signal , wherein the request signal is the communication signal. If the absolute value of the inverse matrix of the propagation path estimation result relating to the signal transmitted to the other party is equal to or greater than the threshold value, the transmission rate request values for all of the plurality of antennas are included, and the absolute matrix of the inverse matrix of the propagation path estimation result is When the value is smaller than the threshold value, only the transmission rate request value for one antenna having a good quality among the plurality of antennas is included, and the transmission means transmits to all the plurality of antennas by the request signal. when receiving a rate request value, and transmitting the data at a transmission rate set independently for each antenna, the single antenna by said request signal When receiving only the transmission rate request value to, transmitting the data at a transmission rate set to the same among the plurality of antennas, a configuration.

The communication method of the present invention includes a receiving step of receiving a request signal from a communication partner, and the request signal has an absolute value of an inverse matrix of a propagation path estimation result relating to a signal transmitted to the communication partner equal to or greater than a threshold value. If there is a transmission rate requirement value for all of the plurality of antennas, and the absolute value of the inverse matrix of the propagation path estimation result is smaller than a threshold, the quality of one of the plurality of antennas is good When only the transmission rate request value is received and the transmission rate request value for all of the plurality of antennas is received by the request signal, data is transmitted at a transmission rate set independently for each antenna, and the request signal is transmitted. data at the transmission rate when receiving only transmission rate request value for said one antenna, which is set to the same among the plurality of antennas by And a transmitting step of transmitting.

  As described above, according to the present invention, in the MIMO communication system, transmission rate request signals can be reduced and transmitted without substantially reducing transmission efficiency, and interference when transmitting transmission rate request signals can be achieved. In addition, power consumption can be reduced.

The block diagram which shows the structure of the terminal device which is a communication apparatus which concerns on Embodiment 1 of this invention. The block diagram which shows schematic structure of the transmitter which is an example of the communicating party of the terminal device shown in FIG. The flowchart of the communication system which has the terminal device which concerns on Embodiment 1 of this invention. The block diagram which shows the structure of the terminal device which is a communication apparatus which concerns on Embodiment 2 of this invention. The block diagram which shows the structure of the terminal device which is a communication apparatus which concerns on Embodiment 3 of this invention. (A) A diagram for explaining the principle of MIMO communication, (b) an expression representing the relationship between a transmission signal and a reception signal

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

(Embodiment 1)
FIG. 1 is a block diagram showing a configuration of terminal apparatus 100 which is a communication apparatus according to Embodiment 1 of the present invention.

  In the MIMO communication system communication system, the terminal device 100 according to the first embodiment is used for transmission rate setting for each antenna at the communication partner (request) to the communication partner that sets and transmits the transmission rate independently for each antenna. A signal (CQI: Channel Quality Indicator) is transmitted.

  In this terminal device 100, the absolute value of the determinant of the matrix (the absolute value of the inverse matrix of the propagation path estimation result) of the propagation path estimation result relating to the transmission path of the data transmitted from each transmission antenna of the communication partner is a predetermined value. If the transmission rate request signal is smaller, the transmission rate request signal is reduced by transmitting only the transmission rate request signal of one antenna, and the transmission efficiency is hardly reduced. This is to reduce power consumption. In addition, each terminal device including the terminal device 100 according to the first embodiment will be described as using a CDMA (Code Division Multiple Access) communication method.

  A terminal apparatus (communication apparatus) 100 illustrated in FIG. 1 includes a transmission control unit 110 that performs transmission control on transmission data, and a modulation encoding unit 112 that performs modulation processing and encoding processing on transmitted data. And a transmission unit 114 that converts the frequency into a radio frequency band, and a transmission antenna 116. Furthermore, the terminal device 100 compares the receiving antennas 120-1 and 120-2, the receiving units 122-1 and 122-2, the interference compensating unit 124, and the transmission rate request generating units 126-1 and 126-2. Unit 128, P / S (parallel-serial) conversion unit (indicated by “P / S” in FIG. 1) 130, selection unit 132, decoding unit 134, S / P (serial-parallel) conversion unit ( In FIG. 1, it is indicated by “S / P” 136.

  The transmission control unit 110 performs transmission control of a transmission signal to be transmitted to a transmission apparatus (base station) 200 (see FIG. 2) as a communication partner, stores the transmission signal, and transmits the stored transmission signal to a transmission time. And output to the modulation encoding unit 112.

  The transmission control unit 110 also transmits a transmission rate request signal for each of the transmission antennas 210 and 220 (see FIG. 2) of the communication partner input from the transmission rate request generation units 126-1 and 126-2, and S / P conversion. Transmission control is performed based on the retransmission request signal from unit 136.

  Further, the transmission control unit 110 performs transmission control of the transmission rate request signal based on the selection result input from the selection unit 132. Specifically, the transmission control unit 110 transmits a transmission rate request signal corresponding to the total number of transmission antennas selected by the selection unit 132 or a transmission rate request signal corresponding to a transmission rate request signal for one transmission antenna. Transmission control, and transmission control of information (for example, retransmission request information) indicating whether or not the signal has been correctly received.

  Modulation coding section 112 modulates and encodes transmission data controlled to be transmitted by transmission control section 110 and outputs the data to transmission section 114. The transmission signal subjected to the modulation process and the encoding process is frequency-converted into a radio frequency band by the transmission unit 114 and transmitted via the transmission antenna 116.

  Receiving antennas 120-1 and 120-2 receive data transmitted from a communication partner (here, transmitting apparatus 200 shown in FIG. 2) and output the data to corresponding receiving units 122-1 and 122-2, respectively. .

  The receiving unit 122-1 performs predetermined radio reception processing such as down-conversion on the received signal, which is a radio frequency band signal received by the receiving antenna 120-1, that is, frequency conversion to obtain a baseband signal. To the interference compensation unit 124. Similarly, the receiving unit 122-2 performs predetermined radio reception processing such as down-conversion, that is, frequency conversion, on the received signal that is a signal in the radio frequency band received by the receiving antenna 120-2, that is, frequency conversion, and A signal is obtained and output to the interference compensation unit 124.

  The interference compensation unit 124 performs channel estimation (channel estimation) on the signals output from the reception units 122-1 and 122-2, and performs channel compensation (channel fluctuation compensation) based on the channel estimation result. At the same time, the absolute value of the determinant of the matrix composed of the propagation path estimation results (corresponding to the absolute value | AD-BC | of the inverse matrix of the propagation path estimation results) is output to the comparison unit 128, and the MIMO separation processing described above is performed. The separated received signal is output to the P / S converter 130.

  Specifically, the interference compensation unit 124 first uses a pilot signal included in a signal received by each receiving antenna to connect the first and second transmitting antennas 210 and 220 and the receiving antennas 120-1 and 120-2. Is estimated. In this embodiment, since two antennas are used on both the transmission side and the reception side, 2 × 2 = 4 propagation path characteristics are estimated.

  Next, based on the estimated propagation path characteristic information, the interference compensation unit 124 transmits the signals output from the reception units 122-1 and 122-2 from the first and second transmission antennas 210 and 220. Into substreams. That is, since the received signal is a mixture of data transmitted from the first and second transmission antennas 210 and 220, these two data are obtained using the propagation path characteristics obtained by channel estimation. For example, by multiplying the reception signal by an inverse matrix of a matrix composed of propagation path characteristic information of 2 rows × 2 columns, the mixed data is separated into two substreams sent from the transmission side. Note that the substream separation method includes not only the above-described inverse matrix calculation method but also a method using sequential determination of an equalizer, an MLSE (Maximum Likelihood Sequence Estimation) method, and the like.

  As described above, the interference compensation unit 124 performs the interference compensation process on the received signal converted into the baseband signal, thereby performing propagation path estimation using the signal from the communication partner and each transmission of the communication partner. Data transmitted from the antenna is obtained, and the obtained transmission data is output to the transmission rate request generators 126-1 and 126-2 and the P / S converter 130.

  Note that propagation path estimation refers to the magnitude of propagation path fluctuation (line fluctuation) affected by fading and other factors in the propagation path from when a radio signal is transmitted from the transmission side to the reception antenna on the reception side. Is estimated (see FIG. 6).

  By estimating the propagation path characteristics in this way, the interference compensation unit 124, in this embodiment, the propagation path characteristics (channel estimation values) A, B, C, and D output to the comparison unit 128 (see FIG. 6). The absolute value of the determinant of the matrix consisting of (hereinafter referred to as “the absolute value of the inverse matrix of the propagation path estimation result”) | AD-BC | can be calculated without separately calculating.

  The transmission rate request generation units 126-1 and 126-2 are similar to the propagation path estimation of the interference compensation unit 124 for each antenna (for example, the first and second transmission antennas 210 and 220 shown in FIG. 2) of the communication partner. The channel quality is estimated based on the propagation path estimation, and a transmission rate request signal CQI for each antenna of the communication partner is generated.

  That is, the channel quality estimation method performed by the transmission rate request generation units 126-1 and 126-2 is as described later, in which the terminal device 100 has two receiving antennas and the terminal device 100 is a communication partner as described later. When there are two transmitting antennas of the transmitting apparatus 200 (see FIG. 2), it can be calculated from four propagation path estimation results. For example, the channel quality information (hereinafter referred to as “quality information”) of the first transmitting antenna 210 (see FIG. 2) and the second transmitting antenna 220 (see FIG. 2) is the propagation path estimation result A of the four systems in FIG. It can be calculated using B, C, and D. The quality information of the first transmission antenna 210 may be | A | + | C |, and the quality information of the second transmission antenna 220 may be | B | + | D |. The quality estimation method shown here is merely an example, and the present invention is not limited to the quality estimation result shown here, and it is needless to say that any quality estimation method may be used.

  As described above, the transmission rate request generation units 126-1 and 126-2 correspond to the transmission antennas on the communication partner side (for example, the first and second transmission antennas 210 and 220 shown in FIG. 2), respectively. The quality estimation result including each transmission rate request signal is output to selection section 132.

  The comparison unit 128 includes an absolute value of a determinant of a matrix formed of the propagation path estimation result generated by the interference compensation unit 124 (here, an absolute value | AD−BC | of an inverse matrix of the propagation path estimation result), a threshold value, and the like. Are compared, and the result is output to the selector 132. Here, the comparison result calculated by the comparison unit 128 indicates whether or not to transmit a transmission rate request to be transmitted to the communication partner side that transmits data to the terminal device 100 by the number of antennas on the partner side. .

  The selection unit 132 includes quality estimation results (including transmission rate request signals for the respective transmission antennas of the communication partner), which are input from the transmission rate request generation units 126-1 and 126-2, and correspond to the respective antennas of the communication partner side. ), Information input from the comparison unit 128, and information indicating whether or not the signal has been correctly received input from the S / P conversion unit 136, a transmission rate request signal to be transmitted to the communication partner side is transmitted to all antennas. It is selected whether to input to the transmission control unit 110 for several minutes or input for the number of one antenna. The selection result determined by the selection unit 132 is output to the transmission control unit 110.

  The P / S conversion unit 130 receives data transmitted from the transmission antennas of the communication partner (for example, the first and second transmission antennas 210 and 220 shown in FIG. 2) obtained by the compensation in the interference compensation unit 124, respectively. P / S conversion is performed and output to the decoding unit 134.

  Decoding section 134 performs a decoding process on the data P / S converted from P / S conversion section 130 and outputs the result to S / P conversion section 136. If there is an error in the received signal, the S / P converter 136 outputs information indicating whether or not the signal has been correctly received to the selector 132.

  FIG. 2 is a block diagram showing a schematic configuration of a transmission apparatus which is an example of a communication partner of terminal apparatus 100 according to Embodiment 1 of the present invention shown in FIG.

  2 is used as, for example, a base station, and a plurality of terminal devices that communicate with different data from a plurality of transmission antennas (here, first transmission antenna 210 and second transmission antenna 220). To send to.

  The transmission apparatus 200 includes a modulation encoding unit 213, 223, a transmission unit 215, 225, a reception antenna 240, a reception unit 243, a demodulation unit 245, a decoding unit 247, an S / P conversion unit (“S / P” in FIG. 2). 249) and a transmission control unit 260.

  The transmission control unit 260 performs transmission control on transmission data (transmission signal). Specifically, the transmission control unit 260 stores transmission data and outputs the transmission data to the modulation and coding units 213 and 223 at a predetermined transmission time.

  Further, the transmission control unit 260 performs retransmission control based on retransmission information transmitted from the communication partner (here, the terminal device 100), and transmits each transmission antenna based on a transmission rate request signal transmitted from the communication partner. Transmission rates are set independently for 210 and 220, and transmission data is transmitted based on the set transmission rate.

  Specifically, the transmission control unit 260 performs retransmission control based on the retransmission request, transmission rate request, quality information, information indicating data to be retransmitted, etc., which are input from the S / P conversion unit 249. I do. Here, the retransmission request is information indicating whether or not the received signal has been correctly received by the terminal device 100.

  When the transmission rate request signal transmitted from the communication partner (here, the terminal device 100) is only one transmission antenna, the transmission control unit 260 uses the transmission rate for one transmission antenna. Control is performed so that the same data is transmitted only from or from all transmission antennas 210 and 220. In this case, the modulation coding sections 213 and 223 select the same coding rate and modulation scheme.

  Modulation coding sections 213 and 223 perform data to be transmitted, that is, data transmitted from first and second transmission antennas 210 and 220 included in transmission apparatus 200 (shown as “transmission signal” in FIG. 2). The encoding process and the modulation process are respectively performed and output to the transmission units 215 and 225. Note that the modulation processing in the modulation encoding units 213 and 223 is normally one in which a modulation scheme is set independently for each of the transmission antennas 210 and 220 (3GPP TR25.876). When the transmission rate request signal from 100) is only one antenna, the same coding rate and modulation scheme are set.

  Transmitters 215 and 225 frequency-convert transmission data (transmission signals) that have been subjected to modulation and coding processing to radio frequency bands, and output them to first and second transmission antennas 210 and 220, respectively. Each of the first and second transmission antennas 210 and 220 transmits the transmission data frequency-converted by the transmission units 215 and 225 at the transmission rate set in the communication control unit 260, respectively.

  The reception antenna 240 receives data transmitted from the communication partner and outputs the data to the reception unit 243, and the reception unit 243 converts the frequency of the input reception data into a baseband signal and sends it to the demodulation unit 245. Output.

  Demodulation section 245 performs demodulation processing on the input received data after frequency conversion, and outputs the result to decoding section 247. Here, the transmission apparatus (base station) 200 transmits a transmission rate request signal for one transmission antenna by the communication partner (terminal apparatus 100) or transmission for a plurality of transmission antennas (here, two transmissions). It is identified whether an antenna transmission rate request signal is being transmitted.

  For example, in the case of the present embodiment in which the MIMO communication method is applied to the CDMA (Code Division Multiple Access) communication method, the demodulation unit 245 compares the results of despreading the transmission rate request signals of the transmission antennas 210 and 220. If the difference between the two is large, it is determined that only the transmission rate request signal of one transmission antenna is transmitted.

  Thus, even if the terminal device 100 does not necessarily notify the terminal device 100 of information indicating how many transmission antenna transmission rate request signals are transmitted by the communication partner (the terminal device 100), the transmitting device 200 It is possible to determine how many transmission antennas 100 transmit transmission rate request signals.

  The reception data input from the demodulator 245 configured as described above is subjected to a decoding process in the decoder 247 and output to the S / P converter 249.

  The S / P converter 249 extracts data, retransmission information, and transmission rate request information from the transmission signal transmitted from the communication partner, and inputs the extracted data to the transmission controller 260. That is, the S / P conversion unit 249 sorts the received data (reception signal) from the retransmission request, transmission rate request, quality information, and information indicating the data to be retransmitted notified from the communication partner, and transmits the transmission control unit 260. Output to.

  Next, the operation of the system including the terminal apparatus 100 having the above configuration and the transmission apparatus 200 as a base station will be described with reference to FIG. FIG. 3 is a flowchart of a communication system having communication apparatus (terminal apparatus) 100 (see FIG. 1) and transmitting apparatus 200 (see FIG. 2) according to Embodiment 1 of the present invention.

  First, in step S1, the terminal device 100 receives a transmission signal from the transmission device (base station) 200 that is a communication partner via the reception antennas 120-1 and 120-2, and proceeds to step S2.

  Specifically, in step S1, the reception signal received via the reception antennas 120-1 and 120-2 in the terminal device 100 is converted into a baseband signal by the reception units 122-1 and 122-2. After that, the interference compensation unit 124 performs interference compensation processing. As a result, the absolute value | AD-BC | of the inverse matrix of the propagation path estimation result and the data transmitted from each of the transmission antennas 210 and 220 of the communication partner are generated.

  Using the transmission data from the interference compensator 124, in the terminal device 100, the transmission rate request generators 126-1 and 126-2 transmit each antenna of the communication partner (for example, the first and second transmissions shown in FIG. 2). The channel quality is estimated for each antenna 210, 220), and a transmission rate request signal for each antenna is generated.

  In step S2, terminal apparatus 100 determines whether or not the absolute value of the inverse matrix of the generated propagation path estimation result (the determinant of the matrix composed of the propagation path estimation values) | AD-BC | If it is determined that the value is equal to or greater than the threshold value, the process proceeds to step S3, and if it is smaller than the threshold value, the process proceeds to step S4.

  Specifically, the comparison unit 128 of the terminal device 100 calculates the absolute value | AD-BC | of the inverse matrix of the propagation path estimation result generated by the interference compensation unit 124, and calculates the calculated | AD-BC | The threshold value is compared to determine whether the threshold value is large or small (in this case, whether or not it is larger than the threshold value).

  Based on this determination, the comparison unit 128 outputs, to the selection unit 132, information indicating whether transmission rate requests are transmitted for the number of antennas. When the comparison unit 128 outputs information for transmitting a transmission rate request for the number of transmission antennas to the selection unit 132, the process of step S3 is performed, and information for not transmitting the number of antennas to the selection unit 132 is output. In step S4, the process is performed.

  In step S3, the terminal device 100 transmits the transmission rate request values of all transmission antennas (here, the first and second transmission antennas 210 and 220) in the communication partner to the communication partner (transmission device 200), and in step S5. Migrate to

  More specifically, in step S3, the comparison unit 128 outputs information on whether or not to transmit a transmission rate request for the number of transmission antennas of the communication partner to the selection unit 132, and from this information, the selection unit 132 transmits the transmission rate request. Select the information to be transmitted for the number of antennas. Then, the selection unit 132 transmits the transmission rate request values (transmission rate) input from the transmission rate request generation units 126-1 and 126-2 corresponding to the selected information together with the selected information (information to be transmitted for the number of antennas). Request) to the transmission control unit 110. The transmission control unit 110 transmits all antennas (here, the first and second transmission antennas shown in FIG. 2) based on information from the selection unit 132 via the modulation encoding unit 112, the transmission unit 114, and the transmission antenna 116. 210, 220) of the transmission rate request signal is transmitted to the transmitting apparatus 200.

  On the other hand, in step S4, the terminal device 100 compares the transmission rate request values of the respective transmission antennas (for example, the first and second transmission antennas 210 and 220 shown in FIG. 2). Specifically, in step S4, the transmission rate request values of the first transmission antenna 210 and the second transmission antenna 220 are compared to determine whether or not the quality of the first transmission antenna 210 is worse. In step S4, if the quality of the first transmission antenna 210 is worse, the process proceeds to step S6, and the quality of the first transmission antenna 210 is better, that is, the quality of the second transmission antenna 220 is worse. Shifts to step S7.

  Specifically, in step S <b> 4, information that is not transmitted by the number of antennas is input from the comparison unit 128 to the selection unit 132 of the terminal device 100. Then, the selection unit 132 compares information input from the transmission rate request generation units 126-1 and 126-2 (transmission rate request signal values in the first and second transmission antennas 210 and 220 that the communication partner has). If the quality of the first transmission antenna 210 is poor in the selection unit 132, the transmission rate request value of the second transmission antenna 220 is output to the transmission control unit 110, the process proceeds to step S6, and the second transmission antenna 220 is output. If the quality is poor, the transmission rate request value of the first transmission antenna 210 is output to the transmission control unit 110, and the process proceeds to step S7.

  In step S <b> 6, in the terminal device 100, the transmission control unit 110 sends the transmission rate request value of the second transmission antenna 220 included in the transmission device 200 to the transmission device 200 that is a communication partner based on information from the selection unit 132. Is transmitted, and the process proceeds to step S8.

  In step S <b> 7, in the terminal device 100, the transmission control unit 110 sends the transmission rate request value of the first transmission antenna 210 included in the transmission device 200 to the transmission device 200 that is a communication partner based on information from the selection unit 132. Is transmitted, and the process proceeds to step S8.

  When the processing of steps S1 to S4, step S6, and step S7 is performed by the terminal device 100, the transmission signal including the transmission rate request value transmitted from the terminal device 100 through these steps is transmitted to the receiving antenna in the transmitting device 200. 240 is received. The transmission apparatus 200 that has received the transmission signal from the terminal apparatus 100 obtains a transmission rate request value via the reception unit 243, the demodulation unit 245, the decoding unit 247, and the S / P conversion unit 249, and performs steps S5 and S8. Perform the process.

  Specifically, in step S5, when the transmission apparatus 200 (see FIG. 2) receives the transmission rate request values of all the transmission antennas from the terminal apparatus 100, each antenna (first and second transmission antennas 210 and 220). Set the transmission rate independently and send data.

  Specifically, in step S <b> 5, the transmission control unit 260 of the transmission device 200 receives the transmission signal from the terminal device 100 via the reception antenna 240, the reception unit 243, the demodulation unit 245, the decoding unit 247, and the S / P conversion unit 249. Based on the obtained transmission rate request, the transmission rate of each of the transmission antennas 210 and 220 is set to perform data transmission control. That is, the transmission control unit 260 is identical to the first and second transmission antennas 210 and 220 via the modulation and coding units 213 and 223 and the transmission units 215 and 225 based on the transmission rate request value from the terminal device 100. Send the data. For example, the same data is data transmitted from the transmission antenna in the transmission apparatus 200 corresponding to the transmission rate request value from the terminal apparatus 100.

  In step S8, the transmission apparatus 200 transmits all transmission rate request values from the terminal apparatus 100 obtained through the reception antenna 240, the reception unit 243, the demodulation unit 245, the decoding unit 247, and the S / P conversion unit 249. Set as the transmission rate of the antenna and transmit the transmission data at the same transmission rate.

  Thus, in terminal apparatus 100 according to the present invention, the absolute value of the inverse matrix of the propagation path estimation result for the signal transmitted from the communication partner (transmission apparatus 200) (the absolute value of the determinant of the matrix composed of the propagation path estimation result) Is equal to or greater than the threshold value, the transmission rate request values of all transmission antennas (here, the first and second transmission antennas 210 and 220) of the communication partner (transmission apparatus 200) are transmitted. The communication partner (transmission apparatus 200) that has received the transmission rate request value independently for each transmission antenna (here, the first and second transmission antennas 210 and 220) based on the transmission rate request value to be transmitted. Set the transmission rate and send.

  On the other hand, in terminal device 100, when the absolute value of the inverse matrix of the propagation path estimation result in the signal transmitted from the communication partner (transmission device 200) is smaller than the threshold value, all transmission antennas of the communication partner (transmission device 200) The transmission rate request value of a smaller number of transmission antennas (here, one) is transmitted. Upon receiving this transmission rate request value, the communication partner (transmission apparatus 200) sets the transmission rate based on the transmission rate request value from the terminal apparatus 100 as the same transmission rate for all transmission antennas, and transmits transmission data from all transmission antennas. Send.

  Specifically, the terminal device 100 determines that the absolute value of the inverse matrix of the propagation path estimation result is smaller than the threshold value, and the quality of one transmission antenna (here, the first transmission antenna 210) is poor. In this case, the transmission rate request signal of the other transmission antenna (here, the second transmission antenna 220) is transmitted to the transmission apparatus 200 that is the communication partner. Then, the transmission apparatus 200 sets the notified transmission rate request value of the transmission antenna (second transmission antenna 220) as the same transmission rate for all the transmission antennas, and transmits the transmission data.

  Further, when the terminal device 100 determines that the absolute value of the inverse matrix of the propagation path estimation result is smaller than the threshold value and the quality of the other transmitting antenna (here, the second transmitting antenna 220) is worse, The transmission rate request signal of the first transmission antenna 210 that is the transmission antenna of the first transmission antenna is transmitted to the transmission device 200 that is the communication partner. Then, the transmitting apparatus 200 sets the notified transmission rate request value of one transmitting antenna (first transmitting antenna 210) as the same transmission rate for all the antennas, and transmits the transmission data.

  In addition, when the absolute value of the inverse matrix of the propagation path estimation result for the signal transmitted from the communication partner calculated in the terminal device 100 is smaller than the threshold, which of the transmission antennas of the communication partner has In this embodiment, the transmission rate request signal of the antenna having the better quality is transmitted.

  As described above, according to the present embodiment, the transmission rate request value transmitted from the terminal device 100 side is the inverse matrix of the propagation path estimation result using the signals transmitted from the transmission antennas 210 and 220 of the transmission device 200. When the absolute value of is smaller than the threshold value, transmission is not performed for all the transmission antennas of the transmission device 200, and only one transmission antenna is transmitted here. In response to this, the transmitting apparatus 200 communicates at the same transmission rate for all antennas. Therefore, the terminal device 100 can reduce the transmission rate request signal with almost no reduction in transmission efficiency, can reduce interference and power consumption, and the transmission device 200 can reduce the downlink without substantially reducing the throughput. The amount of control information can be reduced.

  That is, when the absolute value of the inverse matrix of the propagation path estimation result is small, that is, when MIMO communication (different data is transmitted from a plurality of antennas) is performed in the case of approaching 0, the quality is greatly deteriorated. Conventionally, in such a propagation environment, processing such as transmission from only one antenna or transmission of the same data from a plurality of antennas is performed without performing MIMO communication. When transmitting from only one antenna or transmitting the same data from a plurality of antennas, transmission rate request signals corresponding to the number of antennas are not necessary, and only one transmission rate request signal may be transmitted to the communication partner.

  Therefore, in this embodiment, when the absolute value of the inverse matrix of the propagation path estimation result is small, a transmission rate request signal for one antenna is transmitted, and the communication partner is set to the same transmission rate for all antennas for communication. By doing so, the transmission rate request signal amount is reduced with almost no reduction in throughput.

  In addition, for example, in a communication method that adaptively changes the transmission rate, it is necessary to transmit information indicating which transmission rate is being transmitted to a communication partner without being limited to the MIMO communication method.

  In particular, in a MIMO communication system in which a transmission rate is set for each antenna, when information indicating which transmission rate is being transmitted is transmitted to the transmitting apparatus side, the number of antennas is doubled, and the amount of control signal in the downlink is also the antenna. It becomes several times.

  On the other hand, in the present embodiment, when the transmitting apparatus 200 communicates at the same transmission rate for all transmitting antennas, only the control information for one antenna is transmitted from the terminal apparatus 100 that is the communication partner of the transmitting apparatus 200. As a result, the amount of downlink control information can be reduced with almost no decrease in throughput.

  In the present embodiment, the number of transmission antennas possessed by the transmission apparatus 200 that is the communication partner of the terminal apparatus 100 is two, but this is not limiting, and the number of transmission antennas on the transmission apparatus side can be arbitrarily set. Not even.

(Embodiment 2)
FIG. 4 is a block diagram showing a configuration of terminal apparatus 300 that is a communication apparatus according to Embodiment 2 of the present invention.

  The terminal apparatus 300 according to the second embodiment has the same number of transmission antennas as the communication partner based on the determinant of the matrix composed of the propagation path estimation results (absolute value | AD-BC | By transmitting information indicating whether a transmission rate request signal is transmitted or only one antenna transmission rate request signal is transmitted to a communication partner, it is possible to use the terminal device 100 of the first embodiment. Further, it is possible to reduce erroneous detection of the transmission rate request signal by the communication partner.

  First, a transmitting apparatus such as a base station with which the terminal apparatus 300 in the second embodiment communicates is the same as the transmitting apparatus 200 (see FIG. 2) in the first embodiment, and only different points will be described and similar. Description of the configuration and operation of is omitted.

  The operation of the transmission apparatus that is the communication partner of the terminal apparatus 300 in the second embodiment is different in the operation of the S / P conversion unit 249 in the transmission apparatus 200 of FIG. That is, in the transmission apparatus according to the second embodiment, referring to transmission apparatus 200 in FIG. 2, S / P conversion section 249 provides information indicating whether or not the reception is correct (for example, whether or not there is an error in the received signal). A retransmission request signal indicating that the transmission rate request signal is extracted based on the number of antenna transmission rate request signals transmitted from the terminal device 300. , And output to the transmission control unit 260.

  Similarly to the transmission apparatus 200 of the first embodiment, the transmission apparatus of the second embodiment is used as a base station of the MIMO communication system applied to the CDMA communication system, and the terminal apparatus 300 has one antenna. It is possible to identify whether the transmission rate request signal is transmitted or the transmission rate request signals for a plurality of antennas (here, two antennas) are transmitted. For identification in such a transmission apparatus, for example, the results of despreading transmission rate request signals at each transmission antenna are compared, and if the difference between the two is large, only the transmission rate request signal for one antenna is transmitted. A method for determining that there is no such method is used.

  In this way, even if the terminal device 300 does not necessarily notify the terminal device 300 of information indicating how many transmission antenna transmission rate request signals are transmitted by the terminal device 300, the base station can transmit the number of transmission terminals. It is possible to determine whether an antenna transmission rate request signal is transmitted.

  However, in order to reduce the erroneous detection of the transmission rate request signal by the transmission device, a method of transmitting information on how many transmission antennas the transmission rate request signal of the terminal device 300 is transmitted to the transmission device Is effective.

  Here, the information on how many transmission antenna transmission rate request signals the terminal apparatus 300 is transmitting may be 1 bit if the number of transmission antennas is two, for example, compared to the transmission rate request signal. Since it is sufficiently small (for example, in 3GPP, the transmission rate request signal requires 5 bits), it may be considered that the amount of uplink control information hardly increases.

  A terminal device 300 shown in FIG. 4 has a configuration in which the selection unit 132 is omitted from the configuration of the terminal device 100 (see FIG. 1) in the first embodiment, and basically has the same configuration. Therefore, in the terminal device 300 of this Embodiment, a different structure from the terminal device 100 (refer FIG. 1) is demonstrated, and about another structure, the same code | symbol is attached | subjected and description is abbreviate | omitted.

  In the terminal device 300 shown in FIG. 4, the transmission rate request generation units 126-1 and 126-2 each include a quality estimation result corresponding to each transmission antenna on the communication partner side (including a transmission rate request signal for each transmission antenna). Is output to the transmission control unit 310. Note that the channel quality estimation method performed by the transmission rate request generation units 126-1 and 126-2 is the same as that described in the first embodiment, and thus the description thereof is omitted.

  The comparison unit 128 compares the size with a threshold value and outputs the result to the transmission control unit 310. Here, the comparison result calculated by the comparison unit 128 transmits the transmission rate request signal to be transmitted to the communication partner side that transmits data to the terminal device 300 in correspondence with the number of transmission antennas on the partner side. It will indicate whether or not.

  The transmission control unit 310 performs transmission control of a transmission signal to be transmitted to a communication partner (for example, the transmission device 200), and stores the transmission signal and modulates and encodes the transmission signal at the transmission time, similar to the transmission control unit 110. To 112.

  Also, the transmission control unit 310 is provided for each transmission antenna (for example, the first and second transmission antennas 210 and 220 shown in FIG. 2) of the communication partner input from the transmission rate request generation units 126-1 and 126-2. Transmission control is performed based on the transmission rate request signal and information indicating whether transmission rate requests input from the comparison unit 128 are transmitted for the number of antennas. Specifically, the transmission control unit 310 receives information indicating whether or not to transmit the transmission rate request input from the comparison unit 128 for the number of transmission antennas, and a transmission rate request signal of the transmission antenna corresponding to this information, Control is performed to transmit to the transmitting device that is the communication partner.

  As described above, in the second embodiment, information indicating whether or not the transmission rate request is transmitted from the terminal device 300 for the number of antennas is transmitted to the communication partner. Thereby, the erroneous detection of the transmission rate request signal in the communication partner can be further reduced as compared with the case of using the terminal device 100 of the first embodiment.

  Note that in the transmission apparatus (base station) 200 (see FIG. 2) that receives a signal from the terminal apparatus 300 according to Embodiment 2, the S / P conversion unit 249 indicates information (for example, retransmission). Request signal) and a transmission rate request signal based on information on how many transmission antenna transmission rate request signals transmitted from the terminal device 300 are transmitted to the transmission control unit 260 (see FIG. 2). Output. A transmission rate based on this information is set to a predetermined transmission antenna, and data is transmitted from this transmission antenna.

(Embodiment 3)
FIG. 5 is a block diagram showing a configuration of terminal apparatus 400 which is a communication apparatus according to Embodiment 3 of the present invention.

  Terminal apparatus 400 in the third embodiment transmits a transmission rate request signal for the number of transmission antennas of the communication partner in comparison section 128 of transmitting apparatus 300 in the second embodiment or a transmission rate request signal for one antenna. The threshold value used for selecting whether to transmit only is variable.

  As shown in FIG. 5, terminal device 400 has a configuration in which the threshold value input to comparison unit 128 of terminal device 300 (see FIG. 4) is the threshold value selected by selection unit 432. Yes. This terminal device 400 has a configuration in which a selection unit 432 is further added to the configuration of the terminal device 300 corresponding to the second embodiment shown in FIG. 4, and the other configurations have the same basic configuration as the terminal device 300. Have. Therefore, the same components are denoted by the same reference numerals, and description thereof is omitted.

  Specifically, in this terminal apparatus 400, the absolute value of the determinant of the matrix composed of the quality estimation result (propagation channel estimation result) input from the interference compensation unit 124 in the comparison unit 128 (the inverse matrix of the channel estimation result) A threshold value for comparison with the difference of the absolute value | AD−BC |) is input from the selection unit 432.

  The selection unit 432 receives a predetermined number of threshold values, and the selection unit 432 selects a threshold value from the input predetermined number of threshold values and outputs the threshold value to the comparison unit 128.

  In the third embodiment, two threshold values “threshold value 1” and “threshold value 2” are set as threshold values to be selected by the selection unit 432. In this embodiment, the case where the number of thresholds is two has been described. However, the present invention is not limited to this, and it is needless to say that any number of thresholds can be used. Even in this case, the comparison result calculated by the comparison unit 128 is output to the transmission control unit 410, and a transmission rate request to be transmitted to the communication partner side that transmits data to the terminal device 400 is equal to the number of antennas on the partner side. It indicates whether or not to transmit.

  The other components in the terminal device 400 and the operational effects obtained by these other components are the same as those in the terminal device 300 according to the second embodiment, and a description thereof will be omitted.

  Note that the optimum value of the threshold value used for selecting the number of transmission antenna transmission rate request signals to be transmitted to a transmission apparatus such as a base station as a communication partner in the selection unit 432 varies depending on various communication conditions. It depends on. In the selection unit 432, for example, in the following case, a predetermined threshold value is set from a plurality of threshold values, and the selected threshold value is output to the comparison unit 128.

1) When selecting and setting a threshold according to the number of users using the line When there are many users, it is necessary to reduce interference with other users. The threshold value selected from the values is set to a large value so that only the transmission rate request signal of one antenna is transmitted as much as possible.

2) When selecting and setting a threshold depending on the remaining battery level of the terminal When the remaining battery level is low, it is necessary to reduce power consumption. The threshold value to be selected is set to a large value so that only the transmission rate request signal of one antenna is transmitted as much as possible.

3) When the threshold is selected and set according to the moving speed of the terminal When the moving speed of the terminal is fast, the transmission rate request signal needs to be transmitted more frequently than when the moving speed is slow. For this reason, the threshold value selected from the plurality of threshold values to be selected is set to a large value so that only the transmission rate request signal of one antenna is transmitted as much as possible.

4) When a threshold is selected and set according to the position where the terminal exists When a terminal exists near the boundary of a cell, interference to other terminals increases. The threshold value selected from among them is set to a large value so that only one antenna transmission rate request signal is transmitted as much as possible.

  Note that the threshold value selection method in terminal apparatus 400 of the third embodiment is an example, and the present invention is not limited to the threshold value selection method described above, and each threshold value is set under an arbitrary condition. Needless to say, it can be changed.

  In the present embodiment, the number of transmission antennas possessed by the transmission apparatus 200 that is the communication partner of the terminal apparatuses 100, 300, and 400 is two, but this is not limiting, and the number of transmission antennas on the transmission apparatus side is arbitrary. Needless to say, it can be set.

  The communication apparatus according to the first aspect of the present invention provides transmission data to a communication partner of a MIMO communication system that transmits different data from a plurality of transmission antennas by independently setting a transmission rate for each transmission antenna, A communication apparatus for transmitting transmission rate request signals for a plurality of transmission antennas, wherein a reception unit that receives a signal from the communication partner and a communication partner based on a reception signal obtained by the reception unit An estimation unit that estimates a transmission path between the transmission unit, a transmission unit that transmits the transmission data and the transmission rate request signal, and a control unit that controls transmission of a signal transmitted from the transmission unit. Is less than a plurality of transmitting antennas based on a comparison result between a predetermined value and an absolute value of a determinant of a matrix composed of propagation path estimation results obtained by the estimation means A configuration for transmitting the transmission rate request signal antenna minutes.

  According to this configuration, a determinant of a matrix composed of propagation path estimation results for a communication partner of a MIMO communication system that transmits different data from a plurality of transmission antennas by independently setting a transmission rate for each transmission antenna. Since the transmission rate request signals of a smaller number of antennas than a plurality of transmission antennas are transmitted based on the comparison result between the absolute value of (the absolute value of the inverse matrix of the propagation path estimation result) and a predetermined value, The transmission rate request signal amount to be transmitted does not double the number of transmission antennas of the communication partner. Therefore, transmission rate request signals can be reduced and transmitted without substantially reducing transmission efficiency, and interference to other receivers (users) when transmitting transmission rate request signals can be reduced. , Power consumption can be reduced.

  In the communication apparatus according to a second aspect of the present invention, in the above configuration, the control unit compares the predetermined value with an absolute value of a determinant of a matrix composed of the propagation path estimation result, and the matrix When the absolute value of the equation is smaller than the predetermined value, a configuration is adopted in which transmission rate request signals of a smaller number of transmission antennas than the plurality of transmission antennas are transmitted.

  According to this configuration, it is possible to reduce the transmission rate request signal without substantially reducing the transmission efficiency when transmitting the transmission rate request signal, and it is possible to reduce interference and power consumption.

  In the communication device according to the third aspect of the present invention, in the above configuration, the control unit is based on a comparison result between an absolute value of a determinant of a matrix composed of the propagation path estimation result and the predetermined value. A configuration is adopted in which a transmission rate request signal of one transmission antenna among the plurality of transmission antennas is transmitted.

  According to this configuration, since the transmission rate request signal of one transmission antenna among the plurality of transmission antennas is transmitted to the communication partner that transmits the transmission rate request signal, the transmission rate is transmitted on the communication partner side. The throughput when receiving the request signal is reduced as compared with the case of receiving the transmission rate request signal for all transmission antennas, and the power consumption when transmitting the transmission rate request signal is reduced to the transmission rate for all transmission antennas. This can be reduced compared to the case of transmitting a request signal.

  In the communication device according to a fourth aspect of the present invention, in the above configuration, the control means transmits a transmission rate request signal corresponding to the number of transmission antennas of the communication partner or a transmission rate request signal of one transmission antenna. The information which shows whether only is transmitted is taken to the communicating party.

  According to this configuration, when the communication partner extracts the transmission rate request signal from the received data, the communication partner transmits a transmission rate request signal corresponding to the number of transmission antennas of the communication partner or the transmission rate of one transmission antenna. Since detection can be performed based on information indicating whether only the request signal is transmitted, it is possible to further reduce the erroneous detection of the transmission rate request signal by the communication partner as compared with the above configuration.

  A communication apparatus according to a fifth aspect of the present invention employs a configuration in which the predetermined value is variable in the above configuration.

  According to this configuration, it is possible to reduce interference with other communication devices (users) when transmitting a transmission rate request signal, compared to the case of using the communication device having the above configuration.

  In the communication method according to the sixth aspect of the present invention, the transmission data and the plurality of transmission antennas are transmitted to a communication partner that transmits different data from a plurality of transmission antennas by independently setting a transmission rate for each transmission antenna. A communication method for transmitting a transmission rate request signal for several minutes, a reception step for receiving a signal from the communication partner, and a propagation path between the communication partner based on the reception signal obtained by the reception step Based on the result of comparison between the estimation step for performing estimation, the absolute value of the determinant of the matrix obtained from the estimation result of the propagation path obtained by the estimation step, and a predetermined value, the number of antennas that is smaller than a plurality of transmission antennas And a transmission step of setting and transmitting a transmission rate request signal.

  According to this method, when transmitting a transmission rate request signal to a communication partner of the MIMO communication method, it is not always necessary to transmit the transmission rate request signal for all the transmission antennas of the communication partner, so that the transmission efficiency is hardly increased. The transmission rate request signal can be reduced without lowering, and interference and power consumption can be reduced.

  A wireless communication system according to a seventh aspect of the present invention includes: a transmitter that transmits different signals from a plurality of transmission antennas by independently setting a transmission rate for each transmission antenna; and A wireless communication system comprising: a receiver that receives a transmission signal from a transmitter and transmits transmission data and transmission rate request signals corresponding to the number of the plurality of transmission antennas to the transmitter; Is transmitted from the transmitter, an estimation unit that performs channel estimation with the transmitter using a transmission signal from the transmitter, a transmission unit that transmits the transmission data and the transmission rate request signal, and Control means for controlling the transmission of the signal to be transmitted, the control means comparing and comparing an absolute value of a determinant of a matrix made up of a propagation path estimation result obtained by the estimation means and a predetermined value. Based on the transmission rate request signal for the number of antennas smaller than the plurality of transmission antennas, and the transmitter has a smaller number of antennas than the plurality of transmission antennas transmitted from the receiver. In the antenna corresponding to the transmission rate request signal, the transmission signal of the antenna with the best channel quality and the transmission signal are used to transmit the same signal from all the transmission antennas, or the transmission with only the antenna with the best channel quality. The structure which performs is taken.

  According to this configuration, the receiver has a smaller number of antennas than the plurality of transmission antennas in the transmitter based on the comparison result between the absolute value of the determinant of the matrix composed of the propagation path estimation results and the predetermined value. The transmission rate request signal for minutes is transmitted. On the other hand, the transmitter uses all the transmission rates and transmission signals of the antenna with the best channel quality in the antenna corresponding to the transmission rate request signal for the number of antennas smaller than the plurality of transmission antennas transmitted from the receiver. The same signal is transmitted from the antenna, or only the antenna having the best channel quality is transmitted. For this reason, the amount of transmission rate request signals transmitted from the receiver to the transmitter that is the communication partner does not double the number of transmission antennas of the transmitter. Therefore, transmission rate request signals can be reduced and transmitted without substantially reducing transmission efficiency, and interference to other receivers (users) when transmitting transmission rate request signals can be reduced. , Power consumption can be reduced. In response to this, the transmitter transmits at the same transmission rate for all antennas or transmits only with the antenna having the best channel quality, so that the downlink control information is hardly reduced. The amount can be reduced.

  The communication device and the communication method according to the present invention can reduce the transmission rate request signal and transmit without substantially reducing the transmission efficiency, and reduce interference and power consumption when transmitting the transmission rate request signal. This is effective and useful when transmitting data in the MIMO communication system.

100, 300, 400 Terminal device (communication device)
110, 260, 310, 410 Transmission control unit 112 Modulation coding unit 114 Transmission unit 124 Interference compensation unit 128 Comparison unit 132, 432 Selection unit 134 Decoding unit 136 S / P conversion unit 200 Transmitting device 210 First transmission antenna 220 Second Transmit antenna

Claims (2)

Receiving means for receiving a request signal from a communication partner;
Transmitting means for transmitting data from a plurality of antennas based on the request signal;
Comprising
The request signal includes transmission rate request values for all the plurality of antennas when the absolute value of the inverse matrix of the propagation path estimation result relating to the signal transmitted to the communication partner is equal to or greater than a threshold value. When the absolute value of the inverse matrix of the estimation result is smaller than the threshold value, it includes only the transmission rate request value for one antenna having good quality among the plurality of antennas
The transmission means includes
When receiving the transmission rate request value for all of the plurality of antennas by the request signal, the data is transmitted at a transmission rate set independently for each antenna,
When only the transmission rate request value for the one antenna is received by the request signal, the data is transmitted at a transmission rate set identically between the plurality of antennas.
Communication device. A receiving step of receiving a request signal from a communication partner; and the request signal includes a plurality of the plurality of plural values when an absolute value of an inverse matrix of a propagation path estimation result relating to a signal transmitted to the communication partner is equal to or greater than a threshold value. If the absolute value of the inverse matrix of the propagation path estimation result is smaller than a threshold value, only the transmission rate requirement value for one antenna having a good quality among the plurality of antennas is included. Is,
When transmission request values for all of the plurality of antennas are received by the request signal, data is transmitted at a transmission rate set independently for each antenna, and only the transmission rate request value for the one antenna is transmitted by the request signal. a transmission step of transmitting the data at the transmission rate if it has been received, which is set to the same among the plurality of antennas,
A communication method comprising:

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