JP4065311B2 - Transmission method and wireless device using the same - Google Patents

Description

  The present invention relates to a transmission technique, and more particularly to a transmission method for transmitting signals from a plurality of antennas and receiving signals by a plurality of antennas and a radio apparatus using the transmission method.

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

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

  One technique for effectively using frequency resources in wireless communication is an adaptive array antenna technique. The adaptive array antenna technology controls the directivity pattern of an antenna by controlling the amplitude and phase of a signal to be processed in each of a plurality of antennas. There is a MIMO (Multiple Input Multiple Output) system as a technique for increasing the data rate by using such adaptive array antenna technology. In the MIMO system, the transmission device and the reception device each include a plurality of antennas, and channels corresponding to the respective antennas are set. That is, the data rate is improved by setting channels up to the maximum number of antennas for communication between the transmission device and the reception device. Furthermore, if an OFDM modulation system is combined with such a MIMO system, the data rate is further increased.

  In the MIMO system, the data rate can be adjusted by increasing or decreasing the number of antennas to be used for data communication. Furthermore, the adjustment of the data rate is made in more detail by applying adaptive modulation. In order to reliably execute such adjustment of the data rate, the transmission device acquires information (hereinafter referred to as “rate information”) on the data rate suitable for the wireless transmission path between the transmission device and the reception device. It is desirable to do. On the other hand, when the rate information is not periodically transmitted in the MIMO system, the transmission device transmits a signal for requesting transmission of the rate information (hereinafter referred to as “rate request signal”) to the reception device.

  Further, combinations of antenna directivity patterns in the transmission apparatus and the reception apparatus in the MIMO system are as follows, for example. One is a case where the antenna of the transmission apparatus has an omni pattern and the antenna of the reception apparatus has a pattern in adaptive array signal processing. Another case is when both the antenna of the transmitting device and the antenna of the receiving device have patterns in adaptive array signal processing. The former can simplify the system, but the latter can improve the characteristics because the directivity pattern of the antenna can be controlled in more detail. In the latter case, in order for the transmission apparatus to perform adaptive array signal processing for transmission, it is necessary to previously receive a known signal for channel estimation from the reception apparatus. In order to improve the accuracy of adaptive array antenna control, it is desirable that the transmission apparatus acquires respective transmission path characteristics between the plurality of antennas included in the transmission apparatus and the plurality of antennas included in the reception apparatus. Therefore, the receiving apparatus transmits a known signal for channel estimation from all antennas. Hereinafter, a known signal for channel estimation transmitted from a plurality of antennas is referred to as a “training signal” regardless of the number of antennas to be used for data communication.

  Under such circumstances, the present inventor has come to recognize the following problems. If an error is included in the determination of the rate information by the receiving apparatus, an error occurs in communication by the MIMO system, resulting in a decrease in transmission quality and an effective data rate. Therefore, the determination of rate information by the receiving device needs to be made accurately. In order to increase the effective data rate, it is desirable that the transmission of signals other than data, for example, rate request signals and training signals, is small between the transmission device and the reception device. Furthermore, when either the transmission device or the reception device is battery-driven, it is desirable that the power consumption be low.

  The present invention has been made in view of such circumstances, and an object of the present invention is to provide a transmission method for improving the accuracy of control when transmitting data and a wireless device using the transmission method.

  In order to solve the above problems, a wireless device according to an aspect of the present invention transmits data corresponding to each antenna from at least one of a plurality of antennas to a wireless device to be communicated corresponding to a variable data rate. Generates a request signal for causing the wireless device to provide information on a data rate suitable for a wireless transmission path between the transmitting device to transmit and the wireless device to be communicated, and transmits the generated request signal as data And a control unit for transmitting the data. When transmitting the request signal, the transmission unit also transmits a known signal corresponding to each of the plurality of antennas from a plurality of antennas including at least one antenna for transmitting data.

  Factors that determine the “data rate” include, for example, a modulation scheme, an error correction coding rate, and the number of antennas used in a MIMO system. Here, the “data rate” may be determined by any combination thereof, or may be determined by one of them.

  According to this aspect, when a request signal is transmitted to a wireless device to be communicated, a known signal is transmitted from a plurality of antennas. Information on the newly generated data rate can be acquired and the accuracy of the information can be improved.

  When transmitting the request signal, the transmission unit may perform beam forming on known signals corresponding to at least a plurality of antennas. In this case, by performing beam forming, the signal strength in the wireless device to be communicated can be increased, and data rate information having a higher value can be acquired.

  You may further provide the selection part which selects at least 1 antenna which should be used when receiving the data from the radio | wireless apparatus of communication object among several antennas. The transmission unit may transmit a known signal from the antenna selected by the selection unit. In this case, since the number of antennas that should transmit control signals is reduced, power consumption can be reduced.

  You may further provide the receiving part which receives the known signal for reception from the radio | wireless apparatus of communication object with a some antenna. The selection unit may derive radio quality corresponding to each of the plurality of antennas based on the known signal received by the reception unit, and preferentially select an antenna with good radio quality.

  “Radio quality” is the quality of a radio channel, which may be evaluated by an arbitrary parameter, and includes, for example, signal strength, delay spread, and interference amount. Moreover, you may evaluate by these combination. In this case, since an antenna with good radio quality is preferentially selected, deterioration of data transmission quality can be suppressed.

  A receiving unit that receives a known signal for reception from a wireless device to be communicated by a plurality of antennas, and a selection unit that selects at least one antenna that should transmit the known signal from the plurality of antennas. Also good. The selection unit may derive radio quality corresponding to each of the plurality of antennas based on a reception known signal received by the reception unit, and may preferentially select an antenna with good radio quality. In this case, the number of antennas to be used for transmission and the number of antennas to be used for reception can be set independently.

  Another aspect of the present invention is also a wireless device. This device is included in a selection unit that selects at least one antenna to be used when receiving data from a wireless device to be communicated among a plurality of antennas, and at least one antenna selected in the selection unit. A transmitting unit that transmits data corresponding to each antenna to the wireless device to be communicated from the selected antenna, and also transmits a known signal corresponding to each antenna from at least one antenna selected by the selecting unit. .

  According to this aspect, since a known signal is transmitted from an antenna that should receive data, it is possible to suppress deterioration of directivity in a wireless device to be communicated and to select an antenna that should receive data, thereby reducing power consumption. .

  Yet another aspect of the present invention is also a wireless device. This device is a wireless device that receives data corresponding to each antenna, the data having a variable data rate transmitted from at least one of a plurality of antennas, and at least for transmitting the data. Based on a known signal transmitted from a plurality of antennas including an antenna other than one antenna and receiving a known signal corresponding to each of the plurality of antennas, and a known signal received by the receiving unit The correlation between the reception response vectors respectively corresponding to the plurality of antennas is calculated from the reception response vector calculation unit calculating the reception response vectors corresponding to the plurality of antennas and the reception response vector calculated by the reception response vector calculation unit. Based on the correlation calculated by the correlation calculation unit and the correlation calculation unit, Comprising a determining unit for determining a that data rate, the.

  According to this aspect, since the correlation between the reception response vectors is taken into consideration, the influence between signals transmitted from each of the plurality of antennas can be reflected, and the accuracy of the determined data rate can be improved.

  Yet another aspect of the present invention is also a wireless device. This device is a wireless device that receives data corresponding to each antenna, the data having a variable data rate transmitted from at least one of a plurality of antennas, and at least for transmitting the data. Based on a known signal transmitted from a plurality of antennas including an antenna other than one antenna and receiving a known signal corresponding to each of the plurality of antennas, and a known signal received by the receiving unit And a reception response vector calculation unit for calculating a reception response vector corresponding to each of the plurality of antennas, and a power ratio between the reception response vectors corresponding to the plurality of antennas from the reception response vector calculated by the reception response vector calculation unit. Based on the power ratio calculation unit that calculates and the power ratio calculated in the power ratio calculation unit, And an determination section for determining a data rate for over data.

  According to this aspect, since the intensity ratio between the reception response vectors is taken into consideration, the influence between the signals transmitted from each of the plurality of antennas can be reflected, and the accuracy of the determined data rate can be improved.

  The known signal received by the receiving unit uses a plurality of carriers, and the determining unit may determine the data rate for the data based on the state of any of the plurality of carriers. “Any of a plurality of carriers” may be the one having the best correlation or intensity ratio in all carriers, the worst one, or one corresponding to a predetermined rule. Moreover, you may make it respond | correspond to one pseudo | simulated carrier by calculating the average of the correlation and intensity ratio in all the carriers. Moreover, you may make it respond | correspond to one pseudo | simulated carrier by calculating the average of the correlation and intensity ratio in a part of carrier. In this case, the present invention can be applied to a system using a plurality of carriers. The “state” may be information indicating the quality of the signal including the correlation and the power ratio.

  The receiving unit further includes a notification unit that receives a request for information about the data rate when receiving the known signal, and notifies the data rate determined by the determining unit as a response to the request received by the receiving unit. Good. In this case, when a known signal is received, a request signal is also received, so that information on the determined data rate can be notified, and highly accurate data rate information can be supplied.

  Yet another aspect of the present invention is also a wireless device. The apparatus includes: a first known signal corresponding to each of at least one of the plurality of antennas; and a plurality of antennas including at least one antenna other than the at least one antenna for transmitting the first known signal. A generation unit that generates a burst signal including data corresponding to each of the corresponding second known signal and at least one antenna for transmitting the first known signal, and a plurality of antennas, A transmission unit that transmits the generated burst signal.

  An example of the “first known signal” is a signal for setting AGC in the wireless device to be communicated, and an example of the “second known signal” is to estimate the characteristics of the transmission path in the wireless device to be communicated. It is a signal for. According to this aspect, since the antenna for transmitting data is the same as the first known signal, the estimation result of the first known signal can be used for data reception on the receiving side, and the data reception characteristics can be improved.

  The generation unit includes a portion corresponding to at least one antenna for transmitting the first known signal and a portion corresponding to an antenna other than the at least one antenna for transmitting the first known signal in the second known signal. May be arranged at different timings. In this case, among the second known signals, a portion corresponding to at least one antenna for transmitting the first known signal corresponds to an antenna other than at least one antenna for transmitting the first known signal. Since the influence of the portion can be reduced, the accuracy of estimation based on the second known signal in the portion corresponding to at least one antenna for transmitting the first known signal can be improved on the receiving side.

  The generation unit increases the number of antennas that should transmit the first known signal up to the number of antennas that should transmit the second known signal, and divides and divides the data corresponding to each of the antennas before being increased Data may correspond to an increased antenna. In this case, since the antenna for transmitting data is the same as the first known signal, the estimation result of the first known signal can be used for data reception on the receiving side, and the data reception characteristics can be improved.

  The generation unit may generate data included in the burst signal while using a plurality of subcarriers, and perform data division in units of subcarriers. In this case, interference between the divided data can be reduced.

  Yet another aspect of the present invention is also a wireless device. This device has a transmitter that transmits a burst signal from each of a plurality of antennas, a burst signal that is to be transmitted from the transmitter, and a known signal that corresponds to each of the plurality of antennas, and is placed in a subsequent stage of the known signal. A generation unit that generates a burst signal including the data to be processed, and a determination unit that determines a data rate of data included in the burst signal generated in the generation unit. In the generation unit, when the data corresponds to at least one of the plurality of antennas, the data is made to correspond to the plurality of antennas by increasing the number of antennas to be supported. When data is made to correspond to a plurality of antennas, the data rate is determined to be lower than the data rate before the data is made to correspond to the plurality of antennas.

  According to this aspect, when data is associated with each of a plurality of antennas, the data rate is lowered even when the characteristics of the wireless transmission path from the associated antenna are not suitable for data transmission. Thus, the occurrence of data errors can be reduced.

  The generation unit uses a plurality of subcarriers for the known signal and data, changes the combination of subcarriers to be used for each of the known signals in units of a plurality of antennas, and When corresponding to a plurality of antennas, a combination of subcarriers in a known signal transmitted from the same antenna as the data may be used for the data. In this case, when data is made to correspond to a plurality of antennas, it is easy to select a subcarrier to be used for each data by using the same subcarrier for a known signal and data corresponding to one antenna. Can be.

  Yet another aspect of the present invention is also a wireless device. This device has a transmitter that transmits a burst signal from each of a plurality of antennas, a burst signal that is to be transmitted from the transmitter, and a known signal that corresponds to each of the plurality of antennas, and is placed in a subsequent stage of the known signal. And a generating unit that generates a burst signal including the data to be processed. When the data corresponds to at least one of the plurality of antennas, the generation unit increases the number of antennas to be supported, thereby causing the data to correspond to the plurality of antennas, the known signal and the data. On the other hand, while using a plurality of subcarriers, the combination of subcarriers to be used for each of the known signals is changed in units of each of the plurality of antennas, and when the data is made to correspond to the plurality of antennas, Means for using for the data a combination of subcarriers with known signals transmitted from the same antenna as the data.

  According to this aspect, when data is made to correspond to a plurality of antennas, by using the same subcarrier for the known signal and data corresponding to one antenna, the selection of the subcarrier to be used for each data is selected. Can be easily done.

  Yet another embodiment of the present invention is a transmission method. This method is a transmission method of transmitting data corresponding to each antenna from at least one of a plurality of antennas to a communication target wireless device corresponding to a variable data rate, When generating a request signal for causing the wireless device to provide information on a data rate suitable for the wireless transmission path between and transmitting the generated request signal as data, at least one for transmitting the data A known signal corresponding to each of the plurality of antennas is also transmitted from a plurality of antennas including antennas other than the antenna.

  Yet another embodiment of the present invention is also a transmission method. This method is a transmission method of transmitting data corresponding to each antenna from at least one antenna among a plurality of antennas to a communication target wireless device, and among the plurality of antennas, from a communication target wireless device At least one antenna to be used when receiving the data is selected, and a known signal corresponding to each antenna is also transmitted from the selected at least one antenna.

  Yet another embodiment of the present invention is also a transmission method. This method includes a step of transmitting data corresponding to each antenna from at least one of a plurality of antennas to a communication target wireless device corresponding to a variable data rate, and a communication target wireless device. Generating a request signal for causing the wireless device to provide information on a data rate suitable for the wireless transmission path. In the transmitting step, when transmitting the generated request signal as data, a known signal corresponding to each of the plurality of antennas is also transmitted from a plurality of antennas including at least one antenna for transmitting data. To do.

  In the transmitting step, beam forming may be performed on known signals corresponding to at least a plurality of antennas when transmitting the request signal. The method further comprises a step of selecting at least one antenna to be used when receiving data from the wireless device to be communicated among the plurality of antennas, and the step of transmitting includes transmitting a known signal from the selected antenna. May be. The method further comprises a step of receiving a known signal for reception from a wireless device to be communicated by a plurality of antennas, and the step of selecting comprises: An antenna with good radio quality may be preferentially selected.

  The method may further comprise a step of receiving a known signal for reception from a wireless device to be communicated by a plurality of antennas, and a step of selecting at least one antenna to transmit the known signal from among the plurality of antennas. . In the selecting step, radio quality corresponding to each of the plurality of antennas may be derived based on a received known signal for reception, and an antenna with good radio quality may be preferentially selected.

  Yet another embodiment of the present invention is also a transmission method. The method includes: selecting at least one antenna to be used when receiving data from a wireless device to be communicated among a plurality of antennas; and an antenna included in the selected at least one antenna, Transmitting data corresponding to each antenna to a wireless device to be communicated, and also transmitting a known signal corresponding to each antenna from at least one selected antenna.

  A burst signal to be transmitted in the transmitting step and generating a burst signal including a known signal and data; and determining a data rate of data included in the burst signal generated in the generating step And in the generating step, if the data corresponds to at least one of the antennas to which the known signal is to be transmitted, the number of antennas to be transmitted is increased to increase the number of antennas to which the known signal is to be transmitted. In the step of associating and determining the data, in the step of generating, when the data is associated with the antenna to which the known signal is to be transmitted, the data before the data is associated with the antenna to which the known signal is to be transmitted. The data rate may be determined to be lower than the rate. The generating step uses a plurality of subcarriers for the known signal and data, and changes a combination of subcarriers to be used for each of the known signals in units of each of the plurality of antennas. When data is associated with an antenna to which a signal is to be transmitted, a combination of subcarriers in a known signal transmitted from the same antenna as the data may be used for the data.

  Generating a burst signal that is a burst signal to be transmitted in the transmitting step and includes the known signal and data, and the generating step includes at least one of the antennas to transmit the known signal. If the data is supported, increasing the number of antennas to be supported to associate the data with the antennas to which the known signal is to be transmitted, and using a plurality of subcarriers for the known signal and the data However, the combination of subcarriers to be used for each known signal is changed for each of the plurality of antennas, and the same as the data when the data is associated with the antenna to which the known signal is to be transmitted. Using a combination of subcarriers in a known signal transmitted from a plurality of antennas for the data. But good.

  Yet another embodiment of the present invention is a reception method. This method is a receiving method for receiving data corresponding to each antenna, which is data of a variable data rate transmitted from at least one of a plurality of antennas, and is at least for transmitting data. Calculates reception response vectors corresponding to multiple antennas based on known signals transmitted from multiple antennas including one antenna other than one antenna and corresponding to each of multiple antennas. Then, a correlation between reception response vectors corresponding to each of the plurality of antennas is calculated from the calculated reception response vector, and a data rate for data is determined based on the correlation.

  Yet another embodiment of the present invention is also a reception method. This method is a receiving method for receiving data corresponding to each antenna, which is data of a variable data rate transmitted from at least one of a plurality of antennas, and is at least for transmitting data. Calculates reception response vectors corresponding to multiple antennas based on known signals transmitted from multiple antennas including one antenna other than one antenna and corresponding to each of multiple antennas. Then, the power ratio between the reception response vectors corresponding to each of the plurality of antennas is calculated from the calculated reception response vector, and the data rate for the data is determined based on the power ratio.

  Yet another embodiment of the present invention is also a reception method. This method is a receiving method for receiving data corresponding to each antenna, which is data of a variable data rate transmitted from at least one of a plurality of antennas, and is at least for transmitting data. Receiving a known signal transmitted from a plurality of antennas including an antenna other than one antenna and corresponding to each of the plurality of antennas; and based on the received known signal, Based on the calculated correlation, a step of calculating a reception response vector corresponding to each antenna, a step of calculating a correlation between reception response vectors corresponding to a plurality of antennas from the calculated reception response vector, and Determining a data rate for the data.

  Yet another embodiment of the present invention is also a reception method. This method is a receiving method for receiving data corresponding to each antenna, which is data of a variable data rate transmitted from at least one of a plurality of antennas, and is at least for transmitting data. Receiving a known signal transmitted from a plurality of antennas including an antenna other than one antenna and corresponding to each of the plurality of antennas; and based on the received known signal, Calculating a reception response vector corresponding to each antenna; calculating a power ratio between reception response vectors corresponding to each of a plurality of antennas from the calculated reception response vector; and calculating the power ratio. And determining a data rate for the data.

  The known signal received in the receiving step uses a plurality of carriers, and the determining step may determine a data rate for data based on any state of the plurality of carriers. The receiving step may further include a step of receiving a request for information about the data rate when receiving the known signal, and notifying the data rate determined in the determining step as a response to the received request.

  Yet another embodiment of the present invention is also a transmission method. This method is applied to each of a plurality of antennas including a first known signal corresponding to each of at least one of the plurality of antennas and an antenna other than at least one antenna for transmitting the first known signal. A corresponding second known signal and a burst signal including data corresponding to each of at least one antenna for transmitting the first known signal are transmitted.

  Yet another embodiment of the present invention is also a transmission method. This method applies to each of a plurality of antennas including a first known signal corresponding to each of at least one of the plurality of antennas and an antenna other than at least one antenna for transmitting the first known signal. A step of generating a corresponding second known signal, a burst signal including data corresponding to each of at least one antenna for transmitting the first known signal, and a step of generating via a plurality of antennas Transmitting the generated burst signal.

  The generating step corresponds to a portion of the second known signal corresponding to at least one antenna for transmitting the first known signal and an antenna other than at least one antenna for transmitting the first known signal. The portions may be arranged at different timings. The generating step increases the number of antennas that should transmit the first known signal up to the number of antennas that should transmit the second known signal, and divides the data corresponding to each of the antennas before being increased, The increased data may correspond to the increased antenna. In the generating step, data included in the burst signal may be generated using a plurality of subcarriers, and the data may be divided in units of subcarriers.

  The generating step amplifies data corresponding to each of the antennas before being increased, increasing the number of antennas to which the first known signal is transmitted to the number of antennas to which the second known signal is to be transmitted. The divided data may be divided into the number of antennas, and the divided data may be associated with each of the antennas that should transmit the second known signal. The generating step uses a plurality of subcarriers for at least the second known signal and data, and uses each subcarrier to be used for each second known signal in units of antennas to which the second known signal is to be transmitted. The combination of subcarriers in the second known signal transmitted from the same antenna as the data is changed when the divided data is associated with each of the antennas to which the second known signal is to be transmitted. It may be used for the data.

  And further comprising determining a data rate of data included in the burst signal generated in the generating step, wherein in the determining step, up to the number of antennas to which the second known signal is to be transmitted in the generating step. In the generating step, the number of antennas that should transmit the first known signal is increased up to the number of antennas that should transmit the second known signal, rather than the data rate when the number of antennas that should transmit the signal is not increased. In this case, the data rate may be lowered.

  Yet another embodiment of the present invention is also a transmission method. In this method, a burst signal is transmitted from each of a plurality of antennas, a burst signal to be transmitted in the transmitting step, and a known signal corresponding to each of the plurality of antennas, and the known signal are arranged in a subsequent stage. Generating a burst signal including the data to be processed, and determining a data rate of data included in the burst signal generated in the generating step. In the generating step, when the data corresponds to at least one of the plurality of antennas, the number of antennas to be supported is increased, so that the data corresponds to the plurality of antennas. When the data is made to correspond to a plurality of antennas in the step, the data rate is determined to be lower than the data rate before the data is made to correspond to the plurality of antennas.

  The generating step uses a plurality of subcarriers for the known signal and data, and changes a combination of subcarriers to be used for each of the known signals in units of a plurality of antennas. , A combination of subcarriers in a known signal transmitted from the same antenna as the data may be used for the data.

  Yet another embodiment of the present invention is also a transmission method. In this method, a burst signal is transmitted from each of a plurality of antennas, a burst signal to be transmitted in the transmitting step, and a known signal corresponding to each of the plurality of antennas, and the known signal are arranged in a subsequent stage. Generating a burst signal including the data to be processed. The step of generating, when the data corresponds to at least one of the plurality of antennas, increasing the number of antennas to be supported, thereby making the data correspond to the plurality of antennas, and the known signal and data When a plurality of subcarriers are used, the combination of subcarriers to be used for each of the known signals is changed for each of the plurality of antennas, and the data is made to correspond to the plurality of antennas. Using a combination of subcarriers in a known signal transmitted from the same antenna as the data for the data.

  Yet another aspect of the present invention is also a wireless device. The apparatus generates a burst signal of a plurality of sequences including a first known signal and a second known signal respectively arranged in a plurality of sequences, and data arranged in at least one of the plurality of sequences. And a second known signal multiplied by the orthogonal matrix by multiplying the second known signal and the data by the orthogonal matrix among the burst signals of the plurality of sequences generated by the generator, A cyclic time shift in the second known signal multiplied by the orthogonal matrix by means of means for generating data increased up to the number of sequences and a time shift amount corresponding to each of the plurality of sequences in units of sequences A transformation unit including means for transforming a burst signal of a plurality of sequences by performing a cyclic time shift in the data increased to the number of the plurality of sequences while performing the sequence unit; And an output unit which outputs a burst signal of the deformed plurality of streams in the form unit. The first known signal included in the burst signals of the plurality of sequences generated by the generation unit has a predetermined period, and at least one of time shift amounts corresponding to each of the plurality of sequences by the deformation unit Is greater than or equal to a predetermined period of the first known signal.

  According to this aspect, even if the number of data series is smaller than the number of second known signal series, the multiplication by the orthogonal matrix and the cyclic time shift process are executed, so the number of data series is determined to be the second known number. Can match the number of signal sequences. In addition, since the same processing as that of the data series is executed for the second known signal, the second known signal can be used by the wireless device to be communicated when data is received. In addition, since the same processing as that of the data series is not performed on the first known signal, the amount of time shift can be increased, and the reception characteristics in the wireless device to be communicated can be improved.

  Yet another embodiment of the present invention is also a transmission method. This method includes a first known signal and a second known signal respectively arranged in a plurality of sequences, and a burst signal of a plurality of sequences including data arranged in at least one of the plurality of sequences. Generating a second known signal multiplied by an orthogonal matrix and data increased to the number of a plurality of sequences by multiplying each of the two known signals and data by an orthogonal matrix; A cyclic time shift in the second known signal multiplied by the orthogonal matrix is performed in units of series according to the time shift amount corresponding to each, and the cyclic in the data increased to the number of multiple series. A plurality of sequences of burst signals modified to include a step of performing a simple time shift on a sequence basis, a second known signal on which a cyclic time shift has been performed, and data. And a step. The first known signal included in the generating step has a predetermined period, and at least one of the time shift amounts corresponding to each of the plurality of sequences in the executing step has the first known signal. The predetermined period or longer.

  The generating step uses a plurality of subcarriers for each of a plurality of sequences of burst signals, and second known signals respectively arranged in the plurality of sequences have different subcarriers for each sequence. May be used. The step of outputting may output the plurality of modified burst signals corresponding to the plurality of antennas.

  Yet another aspect of the present invention is also a wireless device. A data rate suitable for a wireless transmission path between an output unit that outputs data arranged in at least one series to a wireless device to be communicated corresponding to a variable data rate and a wireless device to be communicated And a control unit that generates a request signal for causing the wireless device to provide information on the information and outputs the generated request signal as data from the output unit. When outputting the request signal, the output unit also outputs a known signal arranged in each of the plurality of sequences from a plurality of sequences including at least one sequence for outputting data.

  According to this aspect, when outputting the request signal to the wireless device to be communicated, since the known signals arranged in a plurality of series are output, the data rate information in the wireless device to be communicated, and Information on the data rate newly generated based on the known signal can be acquired, and the accuracy of the information can be improved.

  Yet another aspect of the present invention is also a wireless device. The apparatus includes a first known signal arranged in at least one of a plurality of series, a second known signal arranged in each of the plurality of series, and data arranged in the same series as the first known signal. Are included, and an output unit that outputs the burst signal generated in the generation unit.

  According to this aspect, since the first known signal and the sequence in which data is to be arranged are the same, the estimation result of the first known signal can be used for data reception on the receiving side, and the data reception characteristics can be improved.

  The determination unit further includes a determination unit that determines a data rate of data included in the burst signal generated in the generation unit, and the determination unit includes the number of sequences in which the first known signal is to be arranged up to the number of multiple sequences The generation unit may lower the data rate when increasing the number of sequences in which the first known signal is to be arranged up to the number of multiple sequences than the data rate when not increasing the number.

  Yet another aspect of the present invention is also a wireless device. This apparatus outputs an output unit that outputs a plurality of series of burst signals, a burst signal that is to be output from the output unit, and is arranged in a subsequent stage of a known signal that is arranged in each of the plurality of series. And a determination unit that determines a data rate of data included in the burst signal generated in the generation unit. In the generation unit, when the data is arranged in at least one of the plurality of series, the data is arranged in the plurality of series by increasing the number of series to be arranged, and in the determination unit, the generation unit When the data is arranged in a plurality of series, the data rate is determined to be lower than the data rate before the data is arranged in the plurality of series.

  According to this aspect, when data is arranged in each of a plurality of sequences, the data rate is lowered even when the characteristics of the wireless transmission path from the arranged sequences are not suitable for data transmission. Thus, the occurrence of data errors can be reduced.

  The generation unit uses a plurality of subcarriers for the known signal and data, changes the combination of subcarriers to be used for each of the known signals in units of a plurality of sequences, and When arranging in a plurality of sequences, a combination of subcarriers of known signals arranged in the same sequence as the data may be used for the data.

  Yet another aspect of the present invention is also a wireless device. This apparatus outputs an output unit that outputs a plurality of series of burst signals, a burst signal that is to be output from the output unit, and is arranged in a subsequent stage of a known signal that is arranged in each of the plurality of series. And a generation unit that generates a burst signal including the data to be transmitted. When the data is arranged in at least one of the plurality of series, the generation unit increases the number of series to be arranged, thereby arranging the data in the plurality of series, the known signal and the data On the other hand, while using a plurality of subcarriers, in each unit of a plurality of sequences, the combination of subcarriers to be used for each of the known signals is changed, and when arranging data in a plurality of sequences, Means for using for the data a combination of subcarriers with known signals arranged in the same sequence as the data.

  According to this aspect, when data is arranged in a plurality of sequences, it should be used for each data by using the same subcarrier for known signals and data arranged in one sequence. Subcarrier selection can be facilitated.

  Yet another embodiment of the present invention is also a transmission method. The method includes a step of outputting data arranged in at least one series to a wireless device to be communicated corresponding to a variable data rate, and a data rate suitable for a wireless transmission path between the wireless devices to be communicated. And generating a request signal that is output as data from the output step. In the outputting step, when outputting the request signal, a known signal arranged in each of the plurality of sequences is also output from a plurality of sequences including sequences other than at least one sequence for outputting data.

  Yet another embodiment of the present invention is also a transmission method. In this method, a first known signal arranged in at least one of a plurality of series, a second known signal arranged in each of the plurality of series, and data arranged in the same series as the first known signal And a step of generating a burst signal including the output and a step of outputting the generated burst signal.

  Yet another embodiment of the present invention is also a transmission method. This method includes a step of outputting a plurality of series of burst signals, a burst signal to be output in the outputting step, and a known signal arranged in each of the plurality of series, and arranged in a subsequent stage of the known signal. Generating a burst signal including data. In the generation step, when the data is arranged in at least one of the plurality of series, the number of series to be arranged is increased to arrange the data in the plurality of series, the known signal and the data When a plurality of subcarriers are used, a combination of subcarriers to be used for each of known signals is changed in units of each of the plurality of sequences, and data is arranged in a plurality of sequences. Using a combination of subcarriers with known signals arranged in the same series as the data for the data.

  The step of transmitting further comprising the step of setting at least one of the plurality of antennas for transmitting data based on the signal received from the wireless device to be communicated by the plurality of antennas, wherein at least one of the plurality of antennas to transmit the data At least one antenna set in the setting step may be used as the antenna. The at least one antenna of the plurality of antennas is at least one antenna for transmitting data based on the signal received from the wireless device to be communicated, and the antenna selected in the selecting step A step of setting at least one of the antennas may be further included, and the step of transmitting may use at least one antenna set in the setting step as at least one antenna to which data is to be transmitted.

  The method further comprises setting at least one antenna for transmitting data based on a signal received from a wireless device to be communicated by a plurality of antennas, wherein the generating step includes at least one of the data to be associated with As the antenna, at least one antenna set in the setting step may be used. Each of the plurality of sequences output in the outputting step is associated with each of the plurality of antennas, and outputs data based on signals received from the wireless device to be communicated by the plurality of antennas. A step of setting at least one antenna for output, wherein the step of outputting uses at least one sequence to output data using a sequence corresponding to at least one antenna set in the setting step. Also good.

  Each of the plurality of sequences output in the outputting step is associated with each of the plurality of antennas, and outputs data based on the signal received from the communication target wireless device by the plurality of antennas. Setting at least one antenna for generating the data, and the step of generating uses at least one sequence to which data is arranged as a sequence corresponding to at least one antenna set in the setting step. Also good. The method further comprises a step of generating a burst signal that is to be transmitted in the transmitting step and includes a known signal and data, wherein the generating step includes at least one of the antennas to which the known signal is to be transmitted. If the data corresponds to the signal amplitude, the amplitude of the signal transmitted from the antenna other than the antenna to which the data is to be transmitted is transmitted from the antenna to which the data is to be transmitted. It may be defined to a value smaller than the amplitude of the signal in the portion.

  In the generating step, the amplitude of the signal in a portion transmitted from an antenna other than the antenna to which data is to be transmitted among the second known signals is transmitted from the antenna to which data is to be transmitted among the second known signals. It may be specified to be smaller than the amplitude of the signal in the portion. In the generating step, the amplitude of the signal in the portion of the second known signal that is arranged in a sequence other than the sequence in which the data is to be arranged is arranged in the sequence in which the data is to be arranged in the second known signal. It may be specified to be smaller than the amplitude of the signal in the portion. The method further comprises a step of generating a burst signal that is to be output in the outputting step and includes a known signal and data, wherein the generating step includes at least one of the sequences in which the known signal is to be arranged. In the known signal, the amplitude of the signal in a portion arranged in a sequence other than the sequence in which the data is to be arranged is arranged in the sequence in which the data is to be arranged in the known signal. It may be specified to be smaller than the amplitude of the signal in the portion.

  The method further comprises a step of generating a burst signal that is to be transmitted in the transmitting step and includes a known signal and data, wherein the generating step includes at least one of the antennas to which the known signal is to be transmitted. In the known signal, the number of subcarriers used in the portion transmitted from the antenna other than the antenna to which the data is to be transmitted is determined from the antenna to which the data is to be transmitted. It may be defined to a value smaller than the number of subcarriers used in the transmitted part. In the generating step, the number of subcarriers used in a portion of the second known signal transmitted from an antenna other than the antenna to which data is transmitted is determined from the antenna of the second known signal to which data is to be transmitted. It may be defined to a value smaller than the number of subcarriers used in the transmitted part.

  In the generating step, the number of subcarriers used in the portion of the second known signal that is arranged in a sequence other than the sequence in which the data is to be arranged is set in the sequence in which the data is to be arranged in the second known signal. You may be prescribed | regulated to the value smaller than the number of the subcarriers used in the arrange | positioned part. The method further comprises a step of generating a burst signal that is to be output in the outputting step and includes a known signal and data, wherein the generating step includes at least one of the sequences in which the known signal is to be arranged. In the known signal, the number of subcarriers used in the portion arranged in the sequence other than the sequence where the data is to be arranged is the same as the sequence where the data is to be arranged in the known signal. You may be prescribed | regulated to the value smaller than the number of the subcarriers used in the arrange | positioned part.

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

  ADVANTAGE OF THE INVENTION According to this invention, the precision of the control at the time of transmitting data can be improved.

Example 1
Before describing the present invention in detail, an outline will be described. The first embodiment of the present invention relates to a MIMO system configured by two radio apparatuses (hereinafter, referred to as “first radio apparatus” and “second radio apparatus” for convenience). Both the first wireless device and the second wireless device in the MIMO system perform adaptive array signal processing. In addition, the MIMO system changes the data rate by changing the values of the number of antennas, the modulation scheme, and the error correction coding rate. At that time, the transmitting-side radio apparatus transmits a rate request signal to the receiving-side radio apparatus. For example, when the first wireless device transmits data to the second wireless device, the first wireless device transmits a rate request signal to the second wireless device.

  The second radio apparatus notifies its own rate information to the first radio apparatus, and the rate information includes an error in the following cases. The first is a case where a certain period of time is required after the second wireless device determines the rate information. The second case is when the number of antennas of the first wireless device used for transmission is different when the second wireless device determines the rate information and when receiving data from the first wireless device. A specific description thereof will be described later. The first radio apparatus according to the present embodiment also adds a training signal when transmitting the rate request signal in order to make the rate information acquired from the second radio apparatus accurate. As a result, the second radio apparatus can update the rate information with the training signal, so that the rate information becomes accurate.

  In addition, when transmitting data from the first wireless device to the second wireless device, the first wireless device must derive a transmission weight vector in advance based on the training signal. For this purpose, the first wireless device requests the second wireless device to transmit a training signal (hereinafter, the request signal is referred to as a “training request signal”). The second wireless device transmits a training signal to the first wireless device in accordance with the training request signal. At this time, in order to reduce power consumption, the second radio apparatus transmits a training signal from an antenna that should receive data from the first radio apparatus, instead of transmitting a training signal from all antennas.

  FIG. 1 shows a spectrum of a multicarrier signal according to Embodiment 1 of the present invention. In particular, FIG. 1 shows the spectrum of a signal in the OFDM modulation scheme. One of a plurality of carriers in the OFDM modulation system is generally called a subcarrier, but here, one subcarrier is designated by a “subcarrier number”. Here, as in the IEEE802.11a standard, 53 subcarriers from subcarrier numbers “−26” to “26” are defined. The subcarrier number “0” is set to null in order to reduce the influence of the DC component in the baseband signal. Each subcarrier is modulated by a variably set modulation scheme. As a modulation method, any one of BPSK (Binary Phase Shift Keying), QSPK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), and 64QAM is used.

  Also, convolutional coding is applied to these signals as an error correction method. The coding rate of convolutional coding is set to 1/2, 3/4, and the like. Furthermore, the number of antennas used in the MIMO system is variably set. As a result, the data rate is also variably set by variably setting the modulation scheme, coding rate, and number of antennas. Hereinafter, as described above, information on the data rate is referred to as “rate information”, but the rate information includes values of a modulation scheme, a coding rate, and the number of antennas. Here, unless otherwise required, values of the modulation scheme, coding rate, and number of antennas are not described.

  FIG. 2 shows a configuration of the communication system 100 according to the embodiment of the present invention. The communication system 100 includes a first wireless device 10a and a second wireless device 10b collectively referred to as a wireless device 10. The first radio apparatus 10a includes a first antenna 12a, a second antenna 12b, a third antenna 12c, and a fourth antenna 12d, which are collectively referred to as an antenna 12, and the second radio apparatus 10b is collectively referred to as an antenna 14. A first antenna 14a, a second antenna 14b, a third antenna 14c, and a fourth antenna 14d are included. One of the first radio apparatus 10a and the second radio apparatus 10b corresponds to a transmission apparatus, and the other corresponds to a reception apparatus. One of the first radio apparatus 10a and the second radio apparatus 10b corresponds to a base station apparatus, and the other corresponds to a terminal apparatus.

  Before describing the configuration of the communication system 100, an outline of a MIMO system will be described. It is assumed that data is transmitted from the first radio apparatus 10a to the second radio apparatus 10b. The first radio apparatus 10a transmits different data from each of the first antenna 12a to the fourth antenna 12d. As a result, the data rate is increased. The second radio apparatus 10b receives data from the first antenna 14a to the fourth antenna 14d. Further, the second radio apparatus 10b separates the received data by adaptive array signal processing, and independently demodulates the data transmitted from each of the first antenna 12a to the fourth antenna 12d.

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

  The second radio apparatus 10b operates such that data transmitted from the first antenna 12a to the second antenna 12b can be independently demodulated by adaptive array signal processing. Furthermore, the first radio apparatus 10a also performs adaptive array signal processing from the first antenna 12a to the fourth antenna 12d. In this way, the first radio apparatus 10a on the transmission side also performs adaptive array signal processing, thereby ensuring space division in the MIMO system. As a result, interference between signals transmitted from the plurality of antennas 12 is reduced, so that data transmission characteristics can be improved.

  The first radio apparatus 10a transmits different data from the first antenna 12a to the fourth antenna 12d. The first radio apparatus 10a controls the number of antennas 12 to be used according to the rate and capacity of data to be transmitted. For example, if the capacity of data to be transmitted is large, “4” antennas 12 are used, and if the capacity of data to be transmitted is small, “2” antennas 12 are used. The first radio apparatus 10a refers to rate information in the second radio apparatus 10b when determining the number of antennas 12 to be used. For example, when the second radio apparatus 10 b instructs reception using “2” antennas 14, the first radio apparatus 10 a uses “2” antennas 12. Furthermore, the first radio apparatus 10a performs adaptive array signal processing on the antenna 12 when transmitting data. Therefore, the first radio apparatus 10a receives a training signal from the second radio apparatus 10b in advance, and derives a transmission weight vector based on the training signal. Details will be described later.

  The second radio apparatus 10b performs adaptive array signal processing on the first antenna 14a to the fourth antenna 14d and receives data from the first radio apparatus 10a. As described above, the second radio apparatus 10b notifies the first radio apparatus 10a of rate information and transmits a training signal. Note that the operations of the first radio apparatus 10a and the second radio apparatus 10b may be reversed.

  FIGS. 3A and 3B show a burst format configuration in the communication system 100. FIG. FIG. 3A shows a burst format when the number of antennas 12 used is “2”. The upper part of the figure shows a burst signal transmitted from the first antenna 12a, and the lower part of the figure shows a burst signal transmitted from the second antenna 12b. “Legacy STS (Short Training Sequence)”, “Legacy LTS (Long Training Sequence)”, and “Legacy Signal” are compatible with communication systems that do not support MIMO, such as wireless LAN systems compliant with the IEEE 802.11a standard. Is a signal having “Legacy STS” is used for timing synchronization and AGC (Automatic Gain Control), etc., “Legacy LTS” is used for channel estimation, and “Legacy signal” includes control information. The “MIMO signal” and subsequent signals are signals specific to the MIMO system, and the “MIMO signal” includes control information corresponding to the MIMO system. “First MIMO-STS” and “second MIMO-STS” are used for timing synchronization and AGC, etc., “first MIMO-LTS” and “second MIMO-LTS” are used for channel estimation, and “first data And “second data” are data to be transmitted.

  FIG. 3B shows a burst format in the case where “2” antennas 12 are used for data transmission, as in FIG. However, the above training signal is added. In the figure, the training signals correspond to “first MIMO-STS”, “first MIMO-LTS” to “fourth MIMO-STS”, “fourth MIMO-LTS”. Also, “first MIMO-STS”, “first MIMO-LTS” to “fourth MIMO-STS”, and “fourth MIMO-LTS” are transmitted from the first antenna 12 a to the fourth antenna 12 d, respectively. As described above, the number of antennas 12 to which training signals are transmitted may be smaller than “4”. The “first MIMO-STS” to the “fourth MIMO-STS” are configured by patterns that reduce mutual interference. The same applies to “first MIMO-LTS” to “fourth MIMO-LTS”. Here, description of these configurations is omitted. In general, “Legacy LTS” or “first MIMO-LTS” in FIG. 3A may be referred to as a training signal. Here, the training signal is the signal shown in FIG. Limited to. That is, the “training signal” is a sequence corresponding to the transmission path to be estimated regardless of the number of data to be transmitted, that is, the number of series, in order to cause the wireless device 10 to be communicated to perform transmission path estimation. It corresponds to a number of MIMO-LTS. Hereinafter, “first MIMO-STS” to “fourth MIMO-STS” are collectively referred to as “MIMO-STS”, “first MIMO-LTS” to “fourth MIMO-LTS” are collectively referred to as “MIMO-LTS”, “One data” and “second data” are collectively referred to as “data”.

  FIG. 4 is a sequence diagram illustrating a communication procedure to be compared in the communication system 100. Here, an operation in which the first radio apparatus 10a acquires rate information of the second radio apparatus 10b is shown. For the sake of brevity, the operation of adaptive array signal processing is omitted. The first radio apparatus 10a transmits a rate request signal to the second radio apparatus 10b (S10). The second radio apparatus 10b transmits rate information to the first radio apparatus 10a (S12). The first radio apparatus 10a sets a data rate based on the rate information (S14). That is, the data rate is set while referring to the rate information. The first radio apparatus 10a transmits data at the set data rate (S16). The second radio apparatus 10b performs a reception process on the data (S18).

  According to the above operation, as described above, the rate information in the second radio apparatus 10b includes an error in the following cases. The first is a case where a certain period of time is required after the second radio apparatus 10b determines the rate information. That is, the characteristics of the transmission path between the first radio apparatus 10a and the second radio apparatus 10b generally vary, and the content of the rate information varies accordingly. For example, when the rate information is determined, reception at 50 Mbps is possible, but when data is received from the first radio apparatus 10a, reception at 10 Mbps may be limited. The second case is when the number of antennas of the first wireless device used is different when the second wireless device 10b determines the rate information and when receiving data from the first wireless device 10a. That is, when the second radio apparatus 10b determines rate information, if it does not receive training signals from all the antennas 12, an unknown transmission path exists and accurate rate information cannot be derived. For example, if rate information is derived based on signals from the first antenna 12a and the second antenna 12b, the influence of the third antenna 12c and the fourth antenna 12d is not taken into account, and as a result, there is an error in the rate information. included.

  FIG. 5 is a sequence diagram illustrating another communication procedure to be compared in the communication system 100. Here, an operation in which data is transmitted by MIMO is shown. The first radio apparatus 10a transmits a training request signal to the second radio apparatus 10b (S20). The training request signal is included in “first data” and “second data” in FIG. The second radio apparatus 10b transmits a training signal to the first radio apparatus 10a (S22). The first radio apparatus 10a derives a transmission weight vector based on the received training signal and sets it (S24). The first radio apparatus 10a transmits data while using the transmission weight vector (S26). The second radio apparatus 10b derives a reception weight vector for the received data and sets it (S28). Further, the second radio apparatus 10b executes a data reception process based on the reception weight vector (S30).

  According to the above operation, since the second radio apparatus 10b transmits the training signal from all the antennas 14, the power consumption increases. On the other hand, when the data rate in the rate information is somewhat low, the number of antennas 14 to be used may be small. In this case, deterioration in transmission quality can be suppressed without transmitting a training signal from the antenna 14 that is not scheduled to be used. In particular, when the second wireless device 10b is a terminal device and is battery-driven, it is desired to reduce power consumption.

  FIG. 6 shows the configuration of the first radio apparatus 10a. The first radio apparatus 10a includes a first radio unit 20a, a second radio unit 20b, a fourth radio unit 20d, which are collectively referred to as a radio unit 20, and a first processing unit 22a and a second processing unit 22b, which are collectively referred to as a processing unit 22. A fourth processing unit 22d, a first modulation / demodulation unit 24a, a second modulation / demodulation unit 24b, a fourth modulation / demodulation unit 24d, an IF unit 26, a selection unit 28, a control unit 30, and a rate information management unit 32. Including. Further, as signals, a first time domain signal 200a, a second time domain signal 200b, a fourth time domain signal 200d, which are collectively referred to as a time domain signal 200, a first frequency domain signal 202a, which is collectively referred to as a frequency domain signal 202, and a second time domain signal 200b. It includes a frequency domain signal 202b and a fourth frequency domain signal 202d. The second radio apparatus 10b has the same configuration. Also, different configurations are included depending on whether the first radio apparatus 10a or the second radio apparatus 10b is a base station apparatus or a terminal apparatus, but here, in order to clarify the explanation, Omitted.

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

  As a receiving operation, the processing unit 22 converts each of the plurality of time domain signals 200 into the frequency domain, and performs adaptive array signal processing on the frequency domain signal. The processing unit 22 outputs the result of adaptive array signal processing as the frequency domain signal 202. One frequency domain signal 202 corresponds to a signal transmitted from one antenna 14 in FIG. 2, which corresponds to a signal corresponding to one transmission path. As a transmission operation, the processing unit 22 receives the frequency domain signal 202 as a frequency domain signal from the modem unit 24 and performs adaptive array signal processing on the frequency domain signal. Further, the processing unit 22 converts the signal subjected to the adaptive array signal processing into the time domain and outputs it as the time domain signal 200. It is assumed that the number of antennas 12 to be used in the transmission process is specified by the control unit 30. Here, the frequency domain signal 202, which is a frequency domain signal, includes a plurality of subcarrier components as shown in FIG. For the sake of clarity, it is assumed that the signals in the frequency domain are arranged in the order of subcarrier numbers to form a serial signal.

  FIG. 7 shows the structure of a signal in the frequency domain. Here, one combination of subcarrier numbers “−26” to “26” shown in FIG. 1 is referred to as an “OFDM symbol”. In the “i” th OFDM symbol, subcarrier components are arranged in the order of subcarrier numbers “1” to “26” and subcarrier numbers “−26” to “−1”. Also, the “i−1” th OMDM symbol is arranged before the “i” th OFDM symbol, and the “i + 1” th OMDM symbol is arranged after the “i” th OFDM symbol. And

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

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

  A case where a request signal is transmitted with the above configuration will be described. As illustrated in FIG. 3A or 3B, the processing unit 22 transmits data corresponding to each antenna 12 from at least one of the plurality of antennas 12. When the number of antennas 12 to be used is “2”, it corresponds to “first data” and “second data” in FIG. It is assumed that the number of antennas 12 to be used for data transmission is instructed by the control unit 30. Further, the processing unit 22 adds a signal other than data such as “Legacy STS” as shown in FIG. If the number of antennas 12 to be used for data transmission is “4”, “third data” and “fourth data” not shown in FIGS. 3A to 3B are added. . Such data is transmitted to the second radio apparatus 10b corresponding to the variable data rate.

  The control unit 30 generates a request signal for causing the second radio apparatus 10b to provide rate information in the second radio apparatus 10b. Further, the control unit 30 outputs the generated request signal to the modem unit 24. When transmitting the request signal, the processing unit 22 also transmits a known signal corresponding to each of the plurality of antennas 12 from the plurality of antennas 12 including the antenna 12 other than the antenna 12 for transmitting data. Here, the request signal is assigned to “first data” and “second data” in FIG. Further, the known signals correspond to “first MIMO-STS”, “first MIMO-LTS” to “fourth MIMO-STS”, and “fourth MIMO-LTS” in FIG. As a result, as shown in FIG. 3B, even when the number of antennas 12 for transmitting data is “2”, the processing unit 22 transmits known signals, that is, training signals, from “4” antennas 12. To do. In this way, by transmitting the request signal and the training signal in combination, the first radio apparatus 10a causes the second radio apparatus 10b to generate rate information based on the training signal, and the generated rate information is You can get it. As a result, the accuracy of the rate information of the second radio apparatus 10b acquired by the first radio apparatus 10a is improved.

  Corresponding to the above description, a case where a request signal and a training signal are received will be described. The control unit 30 generates rate information based on the received training signal. The generation method of rate information may be arbitrary. For example, the rate information may be generated by measuring the signal strength of the signal received by the radio unit 20 and comparing the measured signal strength with a threshold value. Alternatively, rate information may be generated based on the reception weight vector derived by the processing unit 22. An example of generating rate information will be described later. Further, the rate information may be generated based on the result demodulated by the modem unit 24. The determined rate information is transmitted via the modem unit 24, the processing unit 22, and the radio unit 20, and is held in the rate information management unit 32. The rate information management unit 32 also holds rate information in the wireless device 10 that is symmetrical to communication.

  In the configuration as described above, in order to reduce power consumption, the first radio apparatus 10a operates as follows. The radio unit 20 receives a training signal from the second radio apparatus 10b by the plurality of antennas 12. The selection unit 28 selects at least one of the plurality of antennas 12 to be used when receiving data from the second radio apparatus 10b based on the received training signal. More specifically, it is as follows. The selection unit 28 derives the signal strength corresponding to each of the plurality of antennas 12 based on the training signal received by the radio unit 20. The selection unit 28 preferentially selects the antenna 12 having a high strength. For example, when the number of antennas 12 to be used when receiving data is “3”, the selection unit 28 selects “3” antennas 12 from the antennas 12 having high strength. It is assumed that the total number of antennas 12 to be selected is separately specified based on the data rate to be transmitted and the power consumption value. The processing unit 22 transmits the training signal while using the antenna 12 selected by the selection unit 28. In this way, power consumption is reduced by reducing the number of antennas 12 to which training signals should be transmitted.

  Further, the above operation can be executed even when a request signal is not transmitted. That is, the present invention can also be applied when a training request signal is received from the second radio apparatus 10b. That is, the selection unit 28 selects at least one of the plurality of antennas 12 to be used when receiving data from the second radio apparatus 10b. At this time, the selection is made based on an instruction from the control unit 30. The processing unit 22 transmits data corresponding to each antenna 12 from at least one of the plurality of antennas 12 to the second radio apparatus 10b, and the number of antennas 12 to be used when data is transmitted. Regardless of the training signal, the training signal corresponding to each antenna 12 selected by the selection unit 28 is also transmitted. For example, the data is transmitted from “2” antennas 12 and the training signal is transmitted from “3” antennas 12.

  This configuration can be realized in terms of hardware by a CPU, memory, or other LSI of an arbitrary computer, and in terms of software, it is realized by a program having a reservation management function loaded in memory. The functional block realized by those cooperation is drawn. Accordingly, those skilled in the art will understand that these functional blocks can be realized in various forms by hardware only, software only, or a combination thereof.

  FIG. 8 shows a configuration of the first processing unit 22a. The first processing unit 22a includes an FFT (Fast Fourier Transform) unit 40, a synthesis unit 42, a reference signal generation unit 44, a reception weight vector calculation unit 54, a separation unit 46, a transmission weight vector calculation unit 52, an IFFT unit 48, and a preamble addition Part 50 is included. The synthesis unit 42 includes a first multiplication unit 56 a, a second multiplication unit 56 b, a fourth multiplication unit 56 d, and an addition unit 60 that are collectively referred to as the multiplication unit 56. The separation unit 46 includes a first multiplication unit 58a, a second multiplication unit 58b, and a fourth multiplication unit 58d, which are collectively referred to as a multiplication unit 58.

  The FFT unit 40 receives a plurality of time domain signals 200 and performs a Fourier transform on each of them to derive a frequency domain signal. As described above, in a single frequency domain signal, signals corresponding to subcarriers are serially arranged in the order of subcarrier numbers.

  Multiplier 56 weights the frequency domain signal with the received weight vector from received weight vector calculator 54, and adder 60 adds the output of multiplier 56. Here, since the signals in the frequency domain are arranged in the order of the subcarrier numbers, the reception weight vectors from the reception weight vector calculation unit 54 are also arranged so as to correspond thereto. That is, one multiplication unit 56 sequentially receives reception weight vectors arranged in the order of subcarrier numbers. Therefore, the addition unit 60 adds the multiplication results in units of subcarriers. As a result, the added signals are also serially arranged in the order of subcarrier numbers as shown in FIG. The added signal is the frequency domain signal 202 described above.

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

  The reference signal generation unit 44 stores the “Legacy STS”, “Legacy LTS”, “Legacy LTS”, and “First MIMO-TSS” stored in advance during the “Legacy STS”, “Legacy LTS”, “First MIMO-STS”, and “First MIMO-LTS” periods. “STS” and “first MIMO-LTS” are output as reference signals. In addition to these periods, the frequency domain signal 202 is determined based on a predetermined threshold value, and the result is output as a reference signal. The determination may be a soft determination instead of a hard determination.

  The reception weight vector calculation unit 54 derives a reception weight vector based on the frequency domain signal from the FFT unit 40, the frequency domain signal 202, and the reference signal. The method of deriving the reception weight vector may be any method, and one of them is derivation by an LMS (Least Mean Square) algorithm. Further, the reception weight vector may be derived by correlation processing. In this case, the frequency domain signal and the reference signal are input not only from the first processing unit 22a but also from the second processing unit 22b and the like through a signal line (not shown). The frequency domain signal in the first processing unit 22a is denoted by x1 (t), the frequency domain signal in the second processing unit 22b is denoted by x2 (t), the reference signal in the first processing unit 22a is denoted by S1 (t), the second If the reference signal in the processing unit 22b is represented as S2 (t), x1 (t) and x2 (t) are represented by the following equations.

ここで、雑音は無視する。第１の相関行列Ｒ１は、Ｅをアンサンブル平均として、次の式のように示される。

参照信号間の第２の相関行列Ｒ２は、次の式のように計算される。

Here, noise is ignored. The first correlation matrix R1 is expressed as the following equation, where E is an ensemble average.

The second correlation matrix R2 between the reference signals is calculated as follows:

最終的に、第２の相関行列Ｒ２の逆行列と第１の相関行列Ｒ１を乗算することによって、受信応答ベクトルが導出される。

さらに、受信ウエイトベクトル計算部５４は、受信応答ベクトルから受信ウエイトベクトルを計算する。

Finally, the reception response vector is derived by multiplying the inverse matrix of the second correlation matrix R2 by the first correlation matrix R1.

Further, the reception weight vector calculation unit 54 calculates a reception weight vector from the reception response vector.

  The transmission weight vector calculation unit 52 estimates a transmission weight vector necessary for weighting the frequency domain signal 202 from the reception weight vector. The method for estimating the transmission weight vector is arbitrary, but as the simplest method, the reception weight vector may be used as it is. Alternatively, the reception weight vector may be corrected by a conventional technique in consideration of the Doppler frequency fluctuation of the propagation environment caused by the time difference between the reception process and the transmission process. Here, it is assumed that the reception weight vector is used as it is as the transmission weight vector.

  Multiplier 58 weights frequency domain signal 202 with the transmission weight vector and outputs the result to IFFT unit 48. The IFFT unit 48 performs inverse Fourier transform on the signal from the multiplication unit 58 to convert it into a time domain signal. The preamble adding unit 50 adds a preamble to the head portion of the burst signal as shown in FIGS. Here, “Legacy STS”, “Legacy LTS”, “First MIMO-STS”, and “First MIMO-LTS” are added. The preamble adding unit 50 outputs the signal with the preamble added as the time domain signal 200. The above operation is controlled by the control unit 30 in FIG. In FIG. 8, the first time domain signal 200a and the like are shown in two places. These are signals in one direction, and these correspond to the first time domain signal 200a and the like which are bidirectional signals in FIG.

  The operation of the communication system 100 configured as above will be described. FIG. 9 is a sequence diagram illustrating a procedure for setting a data rate in the communication system 100. FIG. 9 is a sequence diagram when a rate request signal and a training signal are transmitted, and corresponds to FIG. The first radio apparatus 10a transmits a rate request signal and a training signal to the second radio apparatus 10b as shown in FIG. 3B (S40). The second radio apparatus 10b performs transmission path estimation based on the training signal (S42). Here, the transmission path estimation corresponds to the derivation of the reception weight vector described above. The second radio apparatus 10b updates the rate information based on the estimated transmission path (S44). Here, the description of the update of rate information is omitted. The second radio apparatus 10b transmits rate information to the first radio apparatus 10a (S46). The first radio apparatus 10a sets the data rate while referring to the received rate information (S48).

  FIG. 10 is a flowchart showing the procedure for setting the data rate in the first radio apparatus 10a. FIG. 10 corresponds to the operation of the first radio apparatus 10a in FIG. The processing unit 22 transmits a rate request signal in the format of the training signal shown in FIG. 3B (S50). If the IF unit 26 does not receive the rate information via the antenna 12, the radio unit 20, the processing unit 22, and the modem unit 24 (N in S52), it continues to wait until it is received. On the other hand, if the IF unit 26 receives rate information (Y in S52), the control unit 30 sets the data rate (S54). Further, the rate information management unit 32 holds rate information.

  FIG. 11 is a sequence diagram showing another procedure for setting the data rate in the communication system 100. FIG. 11 is a sequence diagram of processing for reducing power consumption in consideration of adaptive array signal processing with respect to FIG. 9, and corresponds to FIG. 5. The first radio apparatus 10a transmits a training request signal to the second radio apparatus 10b (S60). The second radio apparatus 10b transmits a training signal to the first radio apparatus 10a (S62). The first radio apparatus 10a selects the antenna 12 based on the strength of the received training signal (S64). The first radio apparatus 10a transmits a rate request signal and a training signal to the second radio apparatus 10b as shown in FIG. 3B (S66). The training signal is transmitted from the selected antenna 12.

  The second radio apparatus 10b performs transmission path estimation based on the training signal (S68). The second radio apparatus 10b updates the rate information based on the estimated transmission path (S70). The second radio apparatus 10b derives a transmission weight vector and sets it (S72). The second radio apparatus 10b transmits rate information to the first radio apparatus 10a (S74). At this time, adaptive array signal processing is executed by using the transmission weight vector. The first radio apparatus 10a sets a reception weight vector based on the burst signal including rate information (S76). Further, the rate information is received while using the received weight vector (S78). The first radio apparatus 10a sets the data rate while referring to the received rate information (S80).

  FIG. 12 is a flowchart showing another procedure for setting the data rate in the first radio apparatus 10a. FIG. 12 corresponds to the operation of the first radio apparatus 10a in FIG. The processing unit 22 transmits a training request signal (S90). The radio unit 20 receives the training signal (S92). The selection unit 28 measures the strength of the received training signal in units of the antenna 12 and selects the antenna 12 based on the measured strength (S94). The processing unit 22 transmits a training signal from the selected antenna 12 in the format of the training signal shown in FIG. 3B, and also transmits a rate request signal (S96).

  If the IF unit 26 does not receive the rate information via the antenna 12, the radio unit 20, the processing unit 22, and the modem unit 24 (N in S98), it continues to wait until it is received. On the other hand, if the IF unit 26 receives rate information (Y in S98), the processing unit 22 sets a reception weight vector (S100). In addition, the processing unit 22, the modem unit 24, and the IF unit 26 execute reception processing (S102). The control unit 30 sets the data rate (S104). Further, the rate information management unit 32 holds rate information.

  FIG. 13 is a sequence diagram illustrating a communication procedure in the communication system 100. FIG. 13 is a sequence diagram of processing aimed at reducing power consumption in transmission of training signals. The first radio apparatus 10a transmits a training request signal to the second radio apparatus 10b (S110). The second radio apparatus 10b selects the antenna 14 to be used when receiving data (S112). The second radio apparatus 10b transmits a training signal from the selected antenna 14 to the first radio apparatus 10a (S114). The first radio apparatus 10a sets a transmission weight vector based on the strength of the received training signal (S116). The first radio apparatus 10a transmits data to the second radio apparatus 10b using the transmission weight vector (S118). The second radio apparatus 10b derives a reception weight vector from the burst signal including data and sets it (S120). Based on the second radio apparatus 10b and the reception weight vector, reception processing is executed (S122).

  FIG. 14 is a flowchart showing a transmission procedure in the second radio apparatus 10b. FIG. 14 corresponds to the operation of the second radio apparatus 10b in FIG. If the IF unit 26 does not receive the training request signal via the antenna 12, the radio unit 20, the processing unit 22, and the modem unit 24 (N in S130), the process is not started. On the other hand, if the IF unit 26 receives the training request signal (Y in S130), the control unit 30 selects the antenna 14 to be used at the time of reception (S132). The processing unit 22 transmits a training signal from the selected antenna 14 (S134).

  In the embodiments so far, when transmitting the training signal, the first radio apparatus 10a has not performed adaptive array signal processing, that is, beam forming. This is to cause the second radio apparatus 10b to perform transmission path estimation in a state where the antenna directivity is omnidirectional. In other words, this is to cause the second radio apparatus 10b to perform transmission path estimation in a state close to the original transmission path. As described above, when combining the training signal and the rate request signal, the first radio apparatus 10a can increase the rate information determined by the second radio apparatus 10b by executing the following processing. If the first radio apparatus 10a executes beam forming, the SNR (Signal to Noise Ratio) at the time of reception in the second radio apparatus 10b is improved as compared with the case where the first radio apparatus 10a does not perform beam forming. When the second radio apparatus 10b determines the data rate based on the SNR, the determined data rate becomes higher due to the improvement of the SNR. Therefore, here, when transmitting the rate request signal, the first radio apparatus 10a performs beam forming at least on the training signal.

  FIG. 15 is a sequence diagram showing still another procedure for setting the data rate in the communication system 100. The second radio apparatus 10b transmits data to the first radio apparatus 10a (S140). Here, it is assumed that communication has already been performed between the first radio apparatus 10a and the second radio apparatus 10b, and the data rate is set to a predetermined value. The first radio apparatus 10a derives a reception weight vector based on the received data (S142). The first radio apparatus 10a derives a transmission weight vector based on the estimated reception weight vector and sets it (S144). The first radio apparatus 10a performs reception processing on the received data. The first radio apparatus 10a transmits a rate request signal and a training signal to the second radio apparatus 10b as shown in FIG. 3B while performing beamforming using the derived transmission weight vector (S146).

  The second radio apparatus 10b performs transmission path estimation based on the training signal (S148). The second radio apparatus 10b updates the rate information based on the estimated transmission path (S150). The second radio apparatus 10b derives a transmission weight vector and sets it (S152). The second radio apparatus 10b transmits rate information to the first radio apparatus 10a (S154). At this time, adaptive array signal processing is executed by using the transmission weight vector. The first radio apparatus 10a sets a reception weight vector based on the burst signal including rate information (S156). Further, the rate information is received while using the received weight vector (S158). The first radio apparatus 10a resets the data rate while referring to the received rate information (S160).

  FIG. 16 is a flowchart showing yet another procedure for setting the data rate in the first radio apparatus 10a. FIG. 16 corresponds to the operation of the first radio apparatus 10a in FIG. The wireless unit 20 receives data (S170). The processing unit 22 calculates a reception weight vector (S172) and sets a transmission weight vector (S174). The processing unit 22 transmits a training signal from the antenna 12 and also transmits a rate request signal while performing beamforming with the transmission weight vector in the format of the training signal shown in FIG. 3B (S176). .

  If the IF unit 26 does not receive the rate information via the antenna 12, the radio unit 20, the processing unit 22, and the modem unit 24 (N in S178), it continues to wait until it is received. On the other hand, if the IF unit 26 receives rate information (Y in S178), the processing unit 22 sets a reception weight vector (S180). In addition, the processing unit 22, the modem unit 24, and the IF unit 26 perform reception processing (S182). The control unit 30 sets the data rate (S184). Further, the rate information management unit 32 holds rate information.

  Next, generation of rate information will be described. The generation of the rate information is performed in step 44 of FIG. 9 and is performed by the second radio apparatus 10b. When the direction of transmission of the rate request signal is from the second radio apparatus 10b to the first radio apparatus 10a, the rate information is generated also in the first radio apparatus 10a, but here, the second radio apparatus 10b This process will be described. At that time, the configuration of FIG. 6 is changed from the antenna 12 to the antenna 14. FIG. 17 shows the configuration of the control unit 30. The control unit 30 includes a correlation calculation unit 70, a power ratio calculation unit 72, a processing target determination unit 74, a rate determination unit 76, and a storage unit 78.

  As a premise of processing in the control unit 30, as described above, the radio unit 20, the processing unit 22, and the modem unit 24 of FIG. 6 receive the training signal from the first radio apparatus 10a by the antenna 14. As shown in FIG. 3B, the training signal is transmitted from a plurality of antennas 12 including the first antenna 12a and the antenna 12 other than the second antenna 12b for transmitting the first data and the second data. The training signal corresponds to “MIMO-LTS”. Further, each of the training signals is defined so as to correspond to each of the plurality of antennas 12. The reception weight vector calculation unit 54 calculates reception response vectors respectively corresponding to the plurality of antennas 12 based on the received training signals. Since the calculation method of the reception response vector is as described above, the description is omitted. Further, as described above, the OFDM modulation scheme is applied to the received training signal, and a plurality of subcarriers are used. Therefore, the reception response vector is calculated for each of the plurality of subcarriers.

このような相関値Ｓは、ひとつのサブキャリアに対応したものであり、相関計算部７０は、複数のサブキャリアに対応した相関値Ｓをそれぞれ導出する。また、数５のうちの分子が、相関値Ｓであってもよい。 The correlation calculation unit 70 calculates correlations between reception response vectors corresponding to the plurality of antennas 12 from the reception response vectors. In FIG. 1, the transmission path characteristics corresponding to the first antenna 12a, that is, the reception response vectors are shown as “h11”, “h12”, “h13”, and “h14”. Collectively referred to as “h1” and the number of antennas 12 is “2”. Assuming the above, the correlation calculation unit 70 calculates the correlation value S as follows.

Such a correlation value S corresponds to one subcarrier, and the correlation calculation unit 70 derives correlation values S corresponding to a plurality of subcarriers. Further, the numerator in Equation 5 may be a correlation value S.

このような電力比Ｒは、ひとつのサブキャリアに対応したものであり、電力比計算部７２は、複数のサブキャリアに対応した電力比Ｒをそれぞれ導出する。 The power ratio calculation unit 72 calculates the power ratio between the reception response vectors respectively corresponding to the plurality of antennas from the reception response vector. The power ratio calculation unit 72 calculates the power ratio R as follows.

Such a power ratio R corresponds to one subcarrier, and the power ratio calculation unit 72 derives a power ratio R corresponding to a plurality of subcarriers.

  The processing target determination unit 74 inputs a plurality of correlation values S and a plurality of power ratios R corresponding to each of the plurality of subcarriers. The processing target determination unit 74 determines a target to be used when determining the data rate from the plurality of correlation values S and the plurality of power ratios R. One of the determination methods is to select the correlation value S and the power ratio R for any of the plurality of subcarriers. At that time, a measurement unit (not shown) measures the signal strength for each of the subcarriers, and the processing target determination unit 74 selects a subcarrier having a high signal strength. Alternatively, statistical processing, for example, averaging is performed on each of the plurality of correlation values S and the plurality of power ratios R, and the statistically processed correlation value S and the statistically processed power ratio R are calculated. Hereinafter, the correlation value S and the power ratio R determined by the processing target determination unit 74 are also referred to as the correlation value S and the power ratio R.

  The rate determining unit 76 determines the data rate for the data based on the correlation value S and the power ratio R from the processing target determining unit 74. At that time, the determination criterion stored in the storage unit 78 is referred to. FIG. 18 shows the structure of the determination criteria stored in the storage unit 78. The criterion is defined so as to form a two-dimensional space based on the correlation value and the power ratio. As shown in the figure, the two-dimensional space includes a plurality of partial areas “A”, “B”, “C”, “D”. Is divided by. Here, each of the partial areas “A” to “D” corresponds to a predetermined data rate. For example, if it corresponds to the number of antennas 12, “A” corresponds to “4”, “B” corresponds to “3”, “C” corresponds to “2”, “D” "Corresponds to" 1 ".

  Note that the modulation scheme and the coding rate may be defined in the same manner, and the two-dimensional space may be divided into more partial areas by combining these. Returning to FIG. The rate determination unit 76 associates the input correlation value S and the power ratio R with the determination criterion, and specifies a partial region including the input correlation value S and the power ratio R. Further, the rate determining unit 76 derives a predefined data rate from the specified partial area. The control unit 30 executes the above processing when receiving the rate request signal. In addition, when the rate information is transmitted, the determined data rate is included. Note that the rate determination unit 76 may determine the data rate for the data based on either the correlation value S or the power ratio R from the processing target determination unit 74. At that time, the processing can be simplified.

  Next, a burst format obtained by modifying the burst format shown in FIG. As shown in FIG. 3B, the training signal is transmitted from the plurality of antennas 12 in order to cause the second radio apparatus 10b to estimate a plurality of transmission paths. As described above, the part such as “first MIMO-STS” causes the second radio apparatus 10b to set the gain of AGC, and the part such as “first MIMO-LTS” causes the second radio apparatus 10b to estimate the transmission path. . In the configuration of FIG. 3B, the reception characteristics of the first data and the second data may be deteriorated in the following situation. When the propagation loss in the transmission path from the antenna to which no data is transmitted, that is, the third antenna 12c and the fourth antenna 12d is smaller than the propagation loss in the transmission path from other antennas, the “third MIMO-STS” and the “second” Due to “4 MIMO-STS”, the reception intensity at the second radio apparatus 10b increases to some extent. Therefore, AGC sets the gain to a low value. As a result, when the “first data” and the “second data” are demodulated, the gain becomes insufficient and an error is likely to occur. Here, a burst format for suppressing such deterioration of transmission quality will be described. The burst format is formed in the processing unit 22 based on an instruction from the control unit 30.

  FIGS. 19A and 19B show another configuration of the burst format in the communication system 100. FIG. FIG. 19A corresponds to the case where three MIMO-LTSs are respectively assigned to the three antennas 12 and two data are assigned to the two antennas 12 respectively. Here, the steps from “Legacy STS” to “MIMO signal” are the same as those in FIG. “MIMO-LTS” is assigned to each of the three antennas 12 including the antenna 12 other than the antenna 12 for transmitting “MIMO-STS”. That is, the number of antennas 12 to transmit “MIMO-LTS” is determined according to the number of transmission paths to be estimated. On the other hand, the number of antennas 12 that should transmit “MIMO-STS” is matched to the number of antennas 12 that should transmit “data”. That is, “MIMO-STS” and “data” are defined two by two, and each is assigned to the same two antennas 12. Therefore, the signal strength when “data” is received is close to the signal strength when “MIMO-STS” is received when setting the gain of AGC. As a result, it is possible to suppress deterioration in reception quality due to AGC gain.

  In the burst format of FIG. 19A, “MIMO-STS” is transmitted from the antenna 12. Here, “first MIMO-STS” and “second MIMO-STS” are defined to use different subcarriers. For example, “first MIMO-STS” uses subcarriers with odd-numbered subcarrier numbers, and “second MIMO-STS” uses subcarriers with even-numbered subcarrier numbers. This relationship between the use of subcarriers is called “tone interleaving”. Further, in “MIMO-LTS”, tone interleaving is performed between the three antennas 12. When tone interleaving “first MIMO-LTS” or the like, the number of OFDM symbols such as “first MIMO-LTS” or the like is extended to three times that when tone interleaving is not performed.

  FIG. 19B corresponds to the case where two MIMO-LTSs are assigned to two antennas 12 and one data is assigned to one antenna 12. As described above, when there is only one “data”, “MIMO-STS” can be shared with “Legacy STS”. “Legacy STS” is a signal necessary to maintain compatibility with a communication system that does not support the MIMO system, and therefore cannot be omitted. Therefore, “MIMO-STS” is omitted. It can be said that “Legacy STS” corresponds to “MIMO-STS”.

  FIG. 20 shows still another configuration of the burst format in the communication system 100. This corresponds to the case where three MIMO-LTSs are respectively assigned to the three antennas 12 and two data are assigned to the two antennas 12 as in FIG. Further, “MIMO-LTS” is the same as that in FIG. The control unit 30 increases the number of antennas 12 that should transmit “MIMO-STS” to the number of antennas 12 that should transmit “MIMO-LTS”. That is, as illustrated, the number of antennas 12 is increased from “2” in FIG. 19A to “3” in FIG. Further, the data corresponding to each of the antennas 12 before being increased is divided, and the divided data is made to correspond to the increased antenna 12.

  Here, the data corresponding to each of the antennas 12 before being increased corresponds to, for example, “second data” in FIG. The control unit 30 divides the “second data” into “first half data” and “second half data” in FIG. Furthermore, when dividing the data, the control unit 30 performs the data division in units of subcarriers. That is, “first half data” and “second half data” are in a tone interleaving relationship. Also in this case, the signal strength when “data” is received is close to the signal strength when “MIMO-STS” is received when setting the gain of AGC. As a result, it is possible to suppress deterioration in reception quality due to AGC gain.

  FIGS. 21A to 21D show still another configuration of the burst format in the communication system 100. FIG. This also corresponds to the case where three MIMO-LTSs are assigned to the three antennas 12 and two data are assigned to the two antennas 12, respectively, as in FIG. Further, “MIMO-STS” and “data” are the same as those in FIG. The control unit 30 corresponds to a portion of the “MIMO-LTS” corresponding to the antenna 12 for transmitting “MIMO-STS” and an antenna 12 other than the antenna 12 for transmitting “MIMO-STS”. Place the parts at different times. Here, the antennas 12 for transmitting “MIMO-STS” are the first antenna 12a and the second antenna 12b.

  Therefore, portions corresponding to these correspond to “first MIMO-LTS” and “second MIMO-LTS”. On the other hand, the antennas 12 other than the antenna 12 for transmitting “MIMO-STS” are the third antennas 12c. Therefore, the portion corresponding to this is equivalent to “third MIMO-LTS”. As shown in the drawing, these are arranged at different timings. Note that “third MIMO-LTS” is defined to use all subcarriers. According to such a format, when the “first MIMO-LTS” and the “second MIMO-LTS” are amplified by AGC, they are not affected by the “third MIMO-LTS”. Can be accurate. Also in this case, the signal strength when “data” is received is close to the signal strength when “MIMO-STS” is received when setting the gain of AGC. As a result, it is possible to suppress deterioration in reception quality due to AGC gain.

  FIG. 21B corresponds to the case where two MIMO-LTSs are assigned to two antennas 12 and one data is assigned to one antenna 12. As shown in the figure, the configuration corresponds to FIG. FIG. 21C is also in the same situation as FIG. 21B, but “first MIMO-STS” is omitted. It can be said that “Legacy STS” corresponds to “MIMO-STS”. FIG. 21 (d) is the same situation as FIG. 21 (b), but “MIMO signal” is further omitted as compared with FIG. 21 (c). Therefore, the overhead in the burst signal can be reduced. In this case, since the control signal for the MIMO system is not included, it is necessary to recognize in advance that the burst signal is transmitted. For example, a training request signal is transmitted in advance.

  Hereinafter, a modification of the burst format in FIG. 20 will be described. In the burst format of FIG. 20, the number of MIMO-STS, the number of MIMO-LTS, and the number of data are the same. That is, MIMO-STS, MIMO-LTS, and data are transmitted from the three antennas 12, respectively. According to such a burst format, since the number of data is the same as that of MIMO-STS, an error included in the setting of AGC when performing reception processing on data on the receiving side is reduced. Also, since MIMO-LTS is transmitted from a plurality of antennas 12, transmission paths corresponding to the plurality of antennas 12 can be estimated on the receiving side. Furthermore, since the number of MIMO-STS and MIMO-LTS is the same, the accuracy of the transmission path estimated from MIMO-LTS is increased on the receiving side.

  Furthermore, in the modified example described below, the following advantages are added. For example, when the number of antennas 12 is “3” and the data to be transmitted is a “2” series, any of the “2” series data to be transmitted is divided, so that the data is “3”. After being sequenced, they are assigned to each of the “3” antennas 12. In such a case, there are a plurality of combinations of data division and antenna 12 assignment. Furthermore, as the number of antennas 12 increases, the number of combinations also increases. That is, when one of the data series is divided and assigned to one of the antennas 12, the processing may be complicated. The first modification aims at allocating data to the antenna 12 while reducing the processing amount even when the number of data series to be transmitted is smaller than the number of antennas 12. At this time, the number of antennas 12 may be at least the number of antennas 12 to which MIMO-LTS is transmitted.

  FIGS. 22A and 22B show a burst format configuration obtained by modifying the burst format in FIG. 20, and this corresponds to a first modification. In FIGS. 22A and 22B, as in the past, the uppermost stage corresponds to the signal corresponding to the first antenna 12a, the middle stage corresponds to the signal corresponding to the second antenna 12b, and the lowermost stage corresponds to the third antenna 12c. Signals are shown. These may be collectively referred to as a burst signal, or a signal transmitted from one antenna 12 may be referred to as a burst signal. Here, they are used without distinction. The burst signal includes “MIMO-LTS” as a known signal and data. 22A, Legacy STS (hereinafter referred to as “L-STS”), Legacy-LTS (hereinafter referred to as “L-LTS”), Legacy signal (hereinafter referred to as “L-signal”), MIMO signal ( (Hereinafter referred to as “MIMO signal”) is assigned only to the first antenna 12a.

  Subsequent configurations are as follows. In the following description, it is assumed that data should correspond to the two antennas 12. That is, it is assumed that the number of data series is smaller than the number of antennas 12. The control unit 30 in FIG. 6 increases the number of antennas 12 to transmit MIMO-STS and data to the number of antennas 12 to transmit MIMO-LTS. That is, when the data corresponds to at least one of the antennas 12 that should transmit the MIMO-LTS, the control unit 30 should transmit the MIMO-LTS by increasing the number of antennas 12 to be supported. Data is associated with the antenna 12. Here, since the number of antennas 12 that should transmit MIMO-LTS is “3”, the number of antennas 12 that should transmit MIMO-STS and data and data is also “3”. Further, after dividing the data corresponding to each of the antennas 12 before being increased, that is, the data of the “2” series, the divided data is divided into each of the antennas 12 of the number of antennas 12 to which the MIMO-LTS is to be transmitted. To correspond.

  More specifically, the control unit 30 causes the IF unit 26 to combine the “2” series of data into one, and divides the combined data into “3” to “3” antennas 12. assign. The data may correspond to the “2” series and may be a single piece of data. In this case, the data is divided into “3” without collecting the data. The number of antennas 12 may be other than “3”. Here, the data is divided, for example, so that the data amount is substantially equal for each of the plurality of antennas 12. Further, the data may be divided according to a predetermined rule. As a result of the above processing, MIMO-STS, MIMO-LTS, and data are respectively assigned to the three antennas 12 as shown in FIG. In the figure, the data is indicated as “first divided data”, “second divided data”, and “third divided data”.

  As described above, the control unit 30 uses a plurality of subcarriers for MIMO-LTS and data, and uses a combination of subcarriers to be used for each MIMO-LTS in units of each of the plurality of antennas 12. Is changing. That is, the MIMO-LTS corresponding to each of the first antenna 12a to the third antenna 12c uses different subcarriers. In FIG. 22A, the first MIMO-LTS (1) uses 1/3 of all subcarriers, and the second MIMO-LTS (1) is also 1/3 of all subcarriers. The third MIMO-LTS (1) also uses 1/3 of all subcarriers. Furthermore, it is assumed that the subcarriers used in the first MIMO-LTS (1) to the third MIMO-LTS (1) do not overlap. The same relationship holds for the first MIMO-LTS (2) to the third MIMO-LTS (2), and the same relationship holds for the first MIMO-LTS (3) to the third MIMO-LTS (3). Also, the first MIMO-LTS (1), the first MIMO-LTS (2), and the first MIMO-LTS (3) also use different subcarriers. Note that the first MIMO-LTS (1), the first MIMO-LTS (2), and the first MIMO-LTS (3) indicate the MIMO-LTS assigned to different symbols.

  According to the above rule, it can be said that the MIMO-LTSs assigned to the plurality of antennas 12 use different subcarriers for one symbol period. In addition, each MIMO-LTS allocated to one antenna 12 and over a plurality of symbols uses subcarriers different from each other, and all subcarriers to be used as a whole are used. Can be said to use. Further, when associating data with an antenna to transmit MIMO-LTS, a combination of subcarriers in MIMO-LTS transmitted from the same antenna 12 as the data is used for the data. For example, the subcarrier used for the first divided data and the subcarrier used for the first MIMO-LTS (1) are the same. By performing processing in this way, it is possible to assign data to each of the plurality of antennas 12 while reducing the amount of processing for dividing the data.

  In addition, since the first MIMO-LTS and the subcarriers used for data are the same, when a receiving apparatus (not shown) receives MIMO-LTS arranged in a plurality of symbols, at least the transmission path from the first MIMO-LTS is transmitted. The estimation is performed, and the data is demodulated based on the result. Since the subcarriers used for the MIMO-LTS other than the first MIMO-LTS are different from the subcarriers used for the data, even if these are not used for demodulation, deterioration of the demodulation quality is suppressed. . For this reason, the receiving apparatus may skip processing for MIMO-LTS other than the first MIMO-LTS. As a result, the amount of processing can be reduced, and processing similar to that of a receiving device compliant with the IEEE 802.11a standard can be applied.

  FIG. 22 (b) is a modification of FIG. 22 (a), and after MIMO-STS, it is the same as FIG. 22 (a). A MIMO signal from the L-STS is also allocated to the second antenna 12b and the third antenna 12c. At this time, for example, CDD (Cyclic Delay Diversity) is applied to the L-STS assigned to the second antenna 12b and the third antenna 12c. That is, the L-STS assigned to the second antenna 12b is shifted in timing with respect to the L-STS assigned to the first antenna 12a. The same applies to the L-STS assigned to the third antenna 12c.

  FIG. 23 is a flowchart showing a transmission procedure corresponding to the burst format of FIGS. 22 (a)-(b). If it is necessary to transmit the training signal (Y in S220) and the number of antennas 12 to which data is to be transmitted is smaller than the number of antennas 12 to which the training signal is to be transmitted (Y in S222), the control unit 30 Then, subcarriers corresponding to the training signal are acquired for each of the plurality of antennas 12 (S224). Further, the control unit 30 associates data with the antenna 12 to which the training signal is to be transmitted while using the acquired subcarrier (S226). That is, the data corresponding to each of the plurality of antennas 12 are tone interleaved with each other as in the training signal.

  The control unit 30 generates a burst signal from at least the training signal and data (S228). On the other hand, if the number of antennas 12 to transmit data is not smaller than the number of antennas 12 to transmit training signals (N in S222), that is, the number of antennas 12 to transmit data and the training signals are transmitted. If the number of antennas 12 to be equal is equal, the control unit 30 generates a burst signal from at least the training signal and the data (S228). The wireless device 10 transmits a burst signal (S230). If it is not necessary to transmit the training signal (N in S220), the process is terminated.

  Next, a second modification of the burst format in FIG. 20 will be described. When transmitting a MIMO-LTS from a plurality of antennas 12, if the characteristics of the wireless transmission path from any of the plurality of antennas 12 are not suitable for data transmission, the data transmitted from the antennas 12 is transmitted. There is a possibility of mistakes. The second modification is intended to reduce the possibility of erroneous data even when data is transmitted from a plurality of antennas 12. In addition, the burst format in this modification is shown by FIG. 20, FIG. 22 (a)-(b).

  As described above, when the data corresponds to at least one of the antennas 12 that should transmit the MIMO-LTS, the control unit 30 in FIG. 6 performs as shown in FIGS. 20 and 22 (a)-(b). By increasing the number of antennas 12 to be supported, data is associated with the antennas 12 to which the MIMO-LTS is to be transmitted. In addition, the control unit 30 determines the data rate of data included in the burst signal. Further, when the control unit 30 associates data with the antenna 12 to which MIMO-LTS is to be transmitted, the control unit 30 has a data rate lower than the data rate before data is associated with the antenna 12 to which MIMO-LTS is to be transmitted. To decide. For example, if the number of antennas 12 that should transmit MIMO-LTS is “3” and the data is a “2” series, and the data rate of the data in the “2” series is 100 Mbps, “3” The data rate of the data when it is made a series is set to 50 Mbps. The “data rate before associating data with the antenna 12 that should transmit the MIMO-LTS” may be the data rate used in the previous communication, or the characteristics of the transmission path. The data rate determined according to Here, as described above, the data rate is determined by the modulation method, the error correction coding rate, and the number of antennas 12.

  FIG. 24 is a flowchart showing another transmission procedure corresponding to the burst format shown in FIGS. If it is necessary to transmit the training signal (Y in S200) and the number of antennas 12 to which data is to be transmitted is smaller than the number of antennas 12 to which the training signal is to be transmitted (Y in S202), the control unit 30 The data is associated with the antenna 12 that should transmit the training signal (S204). Further, the control unit 30 lowers the data rate of the data (S206). The control unit 30 generates a burst signal from at least the training signal and data (S208). On the other hand, if the number of antennas 12 to transmit data is not smaller than the number of antennas 12 to transmit training signals (N in S202), that is, the number of antennas 12 to transmit data and the training signals are transmitted. If the number of antennas 12 to be equal is equal, the control unit 30 generates a burst signal from at least the training signal and the data (S208). The wireless device 10 transmits a burst signal (S210). If it is not necessary to transmit the training signal (N in S200), the process ends.

  According to the embodiment of the present invention, when transmitting a request signal to a wireless device to be communicated, a training signal is transmitted from a plurality of antennas. Therefore, rate information in the wireless device to be communicated, and Rate information generated based on the training signal can be acquired, and the accuracy of the rate information can be improved. In addition, by using the training signal, the rate information is determined in consideration of the influence of various transmission paths, so that the accuracy of the rate information can be improved. Further, since the request signal and the training signal are continuously transmitted, the latest rate information can be acquired. Further, since the latest rate information can be acquired, the error in the rate information can be reduced even when the propagation path fluctuates. In addition, by transmitting a request signal when rate information of a wireless device to be communicated is required, accurate rate information can be acquired even when the rate information is not periodically transmitted. Further, by improving the accuracy of the rate information, data errors are reduced, and the accuracy of control when transmitting data can be improved. In addition, since the rate request signal and the training signal are transmitted in combination, it is possible to suppress a decrease in the effective data rate.

  In addition, since the number of antennas to which training signals should be transmitted is reduced, power consumption can be reduced. Moreover, since a training signal is transmitted from the antenna to be used for communication, it is possible to suppress deterioration of characteristics. Further, since the power consumption can be reduced, the operation period can be lengthened in the case of battery driving. In addition, since power consumption can be reduced, the wireless device can be downsized. In addition, since an antenna having a high signal strength is preferentially selected, deterioration of data transmission quality can be suppressed. Moreover, since the antenna is selected according to the radio quality, it is possible to suppress the deterioration of the data transmission quality while reducing the power consumption. In addition, since a known signal is transmitted from an antenna that should receive data, deterioration of the transmission weight vector derived in the wireless device to be communicated is suppressed, and an antenna that should receive data is selected, thus reducing power consumption. it can. Moreover, since the derived transmission weight vector can be made accurate, deterioration of antenna directivity can be suppressed.

  Further, by executing beamforming when transmitting the training signal, the signal strength in the wireless device to be communicated can be increased, and rate information having a faster value can be acquired. In addition, since beam forming is also performed when data is actually transmitted, a data rate suitable for data transmission can be acquired. Further, since the correlation value between the reception response vectors and the intensity ratio between the reception response vectors are taken into account when determining the data rate, the influence between the signals transmitted from each of the plurality of antennas can be reflected. In addition, the accuracy of the determined rate information can be improved. Further, in the MIMO system, the transmission characteristics are improved when the correlation value is reduced, and the transmission characteristics are improved when the intensity ratio is reduced. Therefore, the data rate can be determined to reflect such characteristics. The determination of the data rate based on the correlation value and the intensity ratio can be applied to a system using a plurality of carriers. In addition, when receiving the training, the rate request signal is also received, so that the determined rate information can be notified, and highly accurate rate information can be supplied.

  Also, since the antenna for transmitting data is the same as the MIMO-STS, the signal strength when receiving the MIMO-STS when setting the gain of AGC on the receiving side, and the time when data is received The signal strength can be close. In addition, it is possible to suppress deterioration in reception quality due to AGC gain. Further, since the influence of the part corresponding to the antenna other than the antenna for transmitting the MIMO can be reduced with respect to the part corresponding to the antenna for transmitting the MIMO-STS, the MIMO-STS is transmitted on the receiving side. Therefore, it is possible to improve the accuracy of transmission path estimation in the portion corresponding to the antenna for the purpose. Further, interference between the divided data can be reduced.

  In addition, when data is associated with an antenna to which MIMO-LTS is to be transmitted, the data rate is reduced even if the characteristics of the wireless transmission path from the associated antenna are not suitable for data transmission. By doing so, the occurrence of data errors can be reduced. Further, as the number of antennas transmitting MIMO-LTS increases, the number of antennas transmitting MIMO-STS can be increased, and the same data sequence as the number of antennas transmitting MIMO-STS can be transmitted. Further, even when the number of data series is increased, it is possible to suppress a decrease in data transmission quality. In addition, when data is made to correspond to a plurality of antennas, it is easy to select a subcarrier to be used for each data by using the same subcarrier for MIMO-LTS and data corresponding to one antenna. Can be. Further, even when the number of antennas to which MIMO-LTS is to be transmitted and the number of data sequences are changed, the assignment of data to the antennas can be facilitated. Moreover, both effects can be acquired by combining the two modifications with respect to FIG.

(Example 2)
A second embodiment of the present invention relates to a MIMO system as in the first embodiment, and particularly relates to a transmission apparatus in the MIMO system. The transmission apparatus according to the present embodiment corresponds to the transmission function in the first wireless apparatus and the second wireless apparatus in the first embodiment. Furthermore, in the same situation as the situation in which the training signal should be transmitted in the first embodiment, the transmission device transmits the training signal. Here, the description will focus on the burst format including the training signal, and the situation in which the training signal should be transmitted is the same as that in the first embodiment, and thus description thereof is omitted. The transmission apparatus transmits a plurality of sequences of burst signals corresponding to the number of antennas, and arranges a plurality of MIMO-STSs in the plurality of sequences of burst signals. Further, the transmission apparatus arranges a plurality of MIMO-LTSs in a plurality of burst signals following the plurality of MIMO-STSs. Furthermore, the transmission apparatus arranges data in a part of a plurality of series of burst signals. The transmission device multiplies the data by a steering matrix to increase the data to the number of a plurality of sequences. The transmission device also multiplies the steering matrix for MIMO-LTS. However, the transmitter does not multiply the MIMO-STS by a steering matrix. Hereinafter, a plurality of series of burst signals multiplied by the steering matrix are also referred to as “a plurality of series of burst signals” without being distinguished from the above.

  Here, MIMO-STS has a predetermined period. Specifically, a guard interval is added to a signal having a period of 1.6 μs. Note that the steering matrix described above includes a component that causes a cyclic time shift to be performed for each series. The cyclic time shift is called CDD (Cyclic Delay Diversity), and here, a cyclic time shift is performed with respect to the period of the pattern included in the MIMO-LTS. Similar processing is performed on the data. In addition, the time shift amount differs in units of a plurality of series of burst signals, but at least one of these time shift amounts is defined to be equal to or greater than the period of MIMO-STS. As described above, the transmission apparatus deforms a plurality of series of burst signals, and transmits the plurality of modified burst signals of the series from a plurality of antennas.

  The problem corresponding to the above embodiment may be indicated as follows. That is, it is desired to transmit the training signal in a burst format that improves the accuracy of channel estimation in the wireless device to be communicated. It is also desirable to transmit the training signal in a burst format that improves the accuracy of rate information in the wireless device to be communicated. In addition, even when such a training signal is transmitted, it is desired to transmit data in a burst format that suppresses deterioration in data communication quality. Also, I want to use the training signal effectively to receive data.

  FIG. 25 shows a configuration of a transmission apparatus 300 according to Embodiment 2 of the present invention. The transmission apparatus 300 includes an error correction unit 310, an interleaving unit 312, a modulation unit 314, a preamble adding unit 316, a spatial dispersion unit 318, a first radio unit 20a, a second radio unit 20b, and a third radio unit collectively referred to as a radio unit 20. Unit 20c, fourth radio unit 20d, first antenna 12a, second antenna 12b, third antenna 12c, and fourth antenna 12d, collectively referred to as antenna 12. Here, the transmitting apparatus 300 in FIG. 25 corresponds to a part of the first radio apparatus 10a in FIG.

  The error correction unit 310 performs data encoding for error correction. Here, it is assumed that convolutional encoding is performed, and the encoding rate is selected from predetermined values. The interleave unit 312 interleaves the convolutionally encoded data. Further, interleaving section 312 outputs the data after separating it into a plurality of sequences. Here, it is separated into two series. The two series of data can be said to be independent of each other.

  Modulation section 314 performs modulation on each of the two series of data. The preamble adding unit 316 adds a preamble to the modulated data. Therefore, the preamble adding unit 316 stores MIMO-STS, MIMO-LTS, etc. as a preamble. Preamble adding section 316 generates burst signals of a plurality of sequences including MIMO-STS and MIMO-LTS respectively arranged in the plurality of sequences and data arranged in at least one of the plurality of sequences. As described above, data is formed by two series. Here, since the plurality of sequences are “4”, MIMO-STS and MIMO-LTS are respectively arranged in the burst signals of the four sequences, and data is arranged in two of the burst signals of the four sequences. . As a result, the burst adding unit 316 outputs four series of burst signals.

  Here, the details of the MIMO-STS will be omitted, but for example, at least an STS corresponding to one of a plurality of series of burst signals is compared to an STS corresponding to another series of burst signals. It may be defined that at least a part uses different subcarriers. In addition, the STS may be defined so that the number of subcarriers to be used for each STS is equal and different subcarriers are used. Further, as described above, each of a plurality of series of burst signals uses a plurality of subcarriers, and the MIMO-LTS arranged in the plurality of series of burst signals is different for each series. Use a carrier. That is, tone interleaving is performed. Note that each of a plurality of burst signals may be referred to as a “burst signal”, and a plurality of burst signals may be collectively referred to as a “burst signal”, but these are not distinguished here. Shall be used for

  Spatial dispersion section 318 increases the MIMO-LTS multiplied by the steering matrix and the number of the plurality of sequences by multiplying the MIMO matrix and the data by the steering matrix among the burst signals of the plurality of sequences, respectively. Generated data. Here, the spatial distribution unit 318 extends the order of the input data to the number of a plurality of sequences before performing multiplication. The number of input data is “2”, which is represented by “Nin” here. Therefore, the input data is indicated by a vector “Nin × 1”. Further, the number of the plurality of series is “4”, and is represented by “Nout” here. The spatial distribution unit 318 extends the order of the input data from Nin to Nout. That is, the vector “Nin × 1” is expanded to the vector “Nout × 1”. At that time, “0” is inserted into the components from the Nin + 1 line to the Nout line.

ステアリング行列は、「Ｎｏｕｔ×Ｎｏｕｔ」の行列である。また、Ｗは、直交行列であり、「Ｎｏｕｔ×Ｎｏｕｔ」の行列である。直交行列の一例は、ウォルシュ行列である。ここで、ｌは、サブキャリア番号を示しており、ステアリング行列による乗算は、サブキャリアを単位にして実行される。さらに、Ｃは、以下のように示され、ＣＤＤ（Ｃｙｃｌｉｃ Ｄｅｌａｙ Ｄｉｖｅｒｓｉｔｙ）のために使用される。

The steering matrix S is shown as follows.

The steering matrix is a “Nout × Nout” matrix. W is an orthogonal matrix, which is a “Nout × Nout” matrix. An example of an orthogonal matrix is a Walsh matrix. Here, l indicates a subcarrier number, and multiplication by the steering matrix is executed in units of subcarriers. Further, C is shown as follows and is used for CDD (Cyclic Delay Diversity).

  Here, δ represents the shift amount. That is, the spatial dispersion unit 318 performs a cyclic time shift in the MIMO-LTS multiplied by the orthogonal matrix by the shift amount corresponding to each of the plurality of sequences, while performing the number of the plurality of sequences. A cyclic time shift within the data increased up to is executed for each series. The structure of MIMO-LTS has the same structure as Legacy LTS which is LTS in the IEEE802.11a standard. The shift amount is set to a different value for each series. At that time, at least one of the shift amounts corresponding to each of the plurality of sequences is set to be equal to or longer than a predetermined period possessed by the MIMO-STS. Since the period of the MIMO-STS is 1.6 μs, at least one of the shift amounts is set to 1.6 μs, for example. In such a case, even if a time shift is performed on the MIMO-STS, this is equivalent to no shift. Therefore, here, no time shift is performed on the MIMO-STS. As a result of the above processing, the spatial dispersion unit 318 transforms a plurality of series of burst signals.

  The same number of radio units 20 as the antennas 12 are provided. Radio section 20 transmits a plurality of modified burst signals. At that time, the radio unit 20 transmits a plurality of modified burst signals corresponding to the plurality of antennas 12. The radio unit 20 includes an IFFT unit, a GI unit, an orthogonal modulation unit, a frequency conversion unit, and an amplification unit (not shown). The IFFT unit performs IFFT and converts a frequency domain signal using a plurality of subcarrier carriers into a time domain. The GI unit adds a guard interval to the time domain data. The quadrature modulation unit performs quadrature modulation. The frequency converter converts the orthogonally modulated signal into a radio frequency signal. The amplifying unit is a power amplifier that amplifies a radio frequency signal. In addition, the space dispersion | distribution part 318 may be provided in the back | latter stage of the IFFT part which is not shown in figure.

  FIGS. 26A to 26B show burst formats of burst signals generated in the transmission apparatus 300. FIG. FIG. 26A shows a burst format in a plurality of series of burst signals output from the preamble adding unit 316. Since FIG. 26A is equivalent to FIG. Here, “4” MIMO-STS and “4” MIMO-LTS are added to each of “4” series burst signals, which are a plurality of series. On the other hand, data of “2” series, which is at least one of a plurality of series, is added as “first data” and “second data”. FIG. 26B shows a plurality of series burst signals transformed by the spatial dispersion unit 318. MIMO-STS is the same as that shown in FIG. The MIMO-LTS in FIG. 26A is “MIMO-LTS ′” as a result of the multiplication of the steering matrix. In FIG. 26B, this is indicated as “first MIMO-LTS ′” to “fourth MIMO-LTS ′”. The “first data” and “second data” in FIG. 26A are four series of data as a result of multiplication of the steering matrix. In FIG. 26B, this is shown as “first data '” to “fourth data'”.

  According to the embodiment of the present invention, even when the number of data sequences is smaller than the number of MIMO-LTS sequences, multiplication by an orthogonal matrix and cyclic time shift processing are performed. It can match the number of MIMO-LTS sequences. Also, since MIMO-LTS performs the same processing as that of the data sequence, the wireless device to be communicated can use MIMO-LTS when receiving data. In addition, since MIMO-STS does not perform the same processing as that of the data series, the amount of time shift in CDD can be increased, and the reception characteristics in the radio apparatus to be communicated can be improved. Moreover, since MIMO-LTS is transmitted from all antennas, the receiving side can estimate an assumed transmission path. Further, even if the number of data series is not equal to the number of antennas, signals can be transmitted uniformly from all antennas by executing processing on the data using the Walsh matrix and CDD. Further, the power of data can be matched with MIMO-LTS.

  In addition, since processing by Walsh matrix and CDD is also performed for MIMO-LTS, the transmission path estimated by MIMO-LTS can be used as it is for data reception on the receiving side. Also, if CDD is executed with a sufficiently large shift amount for the MIMO-LTS and the data, the power difference between the MIMO-LTS and the data becomes very small, so that the accuracy of AGC setting on the receiving side can be improved. In addition, since the MIMO-STS cannot be time-shifted with a large shift amount, in this case, the MIMO-STS and the MIMO-LTS can be combined with each other by associating the MIMO-STS with all the antennas. Also, the power of MIMO-STS and MIMO-LTS can be combined without performing CDD processing for MIMO-STS. Also, since MIMO-LTS is tone interleaved, transmission power can be maintained even when MIMO-LTS is transmitted from all antennas by processing using Walsh matrix and CDD. Also, when processing by Walsh matrix and CDD is not performed, when transmitting two series of data with three antennas, each power in the burst signal is “three STS” = “three LTS”> “two” “Data”, but when the MIMO-LTS and the data are processed by the Walsh matrix and CDD, “3 STS” = “3 LTS” = “3 data” can be set.

(Example 3)
Example 3 corresponds to an example in which Example 1 and Example 2 are combined. That is, the wireless apparatus generates a training signal configured by a burst format as in the first embodiment, that is, a plurality of series of burst signals. Also, the radio apparatus multiplies the generated burst signals of a plurality of sequences by a steering matrix as in the second embodiment, thereby transforming the burst signals of the plurality of sequences. Further, the wireless device transmits a plurality of modified burst signals from a plurality of antennas. Here, the radio apparatus may multiply each of MIMO-STS, MIMO-LTS, and data included in a plurality of series of burst signals by a steering matrix.

  The wireless device 10 according to the third embodiment is the same type as the first wireless device 10a of FIG. Moreover, the transmission function of the radio | wireless apparatus 10 is the same type as the transmission apparatus 300 of FIG. The control unit 30 and the preamble adding unit 316 are arranged in the same sequence as the MIMO-STS arranged in at least one of the plurality of sequences, the MIMO-LTS arranged in each of the plurality of sequences, and the MIMO-STS. A plurality of series burst signals including data to be processed are generated. Also, the control unit 30 and the preamble adding unit 316 are arranged in a part of the MIMO-LTS arranged in a series in which the MIMO-STS is arranged and in a series other than the series in which the MIMO-STS is arranged in the MIMO-LTS. The parts to be processed are arranged at different timings. As a result, a burst signal having a burst format as shown in FIG. 21A is generated. Furthermore, the spatial dispersion unit 318 transforms the burst signals of the plurality of sequences by multiplying the generated burst signals of the plurality of sequences by a steering matrix. Spatial dispersion section 318 multiplies MIMO-STS by the steering matrix and performs time shift with the shift amount being an arbitrary value. Since other operations are the same as those in the second embodiment, description thereof is omitted.

  FIG. 27 is a diagram illustrating a configuration of a burst format according to the third embodiment of the present invention. FIG. 27 corresponds to a burst format for a plurality of streams of burst signals output from the spatial dispersion unit 318, and corresponds to a burst format obtained by multiplying the burst format of FIG. “First MIMO-STS ′” to “third MIMO-STS ′” in FIG. 27 correspond to the result of multiplying “first MIMO-STS” and “second MIMO-STS” in FIG. . At this time, since the steering matrix corresponds to a “3 × 3” matrix, a row of “0” is added to “first MIMO-STS” and “second MIMO-STS” in FIG. Is expanded to a “3 × 1” vector. “First MIMO-LTS ′” to “third MIMO-LTS ′” in FIG. 27 correspond to the result of multiplying “first MIMO-LTS” and “second MIMO-LTS” in FIG. 21A by the steering matrix. . Also, “fourth MIMO-LTS ′” to “sixth MIMO-LTS ′” in FIG. 27 correspond to the result of multiplying “third MIMO-LTS” in FIG. 21A by the steering matrix. The data is the same as in Example 2.

  Note that burst formats of a plurality of series of burst signals generated by the control unit 30 and the preamble adding unit 316 may correspond to FIGS. 22 (a) to 22 (b). Since the explanation of these burst formats is the same as that in the first embodiment, a description thereof will be omitted, but the spatial dispersion unit 318 multiplies such a burst signal by a steering matrix. The plurality of series burst signals, which are the above training signals, may be transmitted at the timing described in the first embodiment. That is, the control unit 30 generates a rate request signal for causing the wireless device 10 to provide information on the data rate corresponding to the wireless transmission path between the wireless device 10 and the wireless device 10 generates the generated rate. In transmitting the request signal, the training signal may be used. Details are the same as those in the first embodiment, and a description thereof will be omitted. The invention described in the first embodiment is applied to the third embodiment by replacing the plurality of antennas 12 in the first embodiment with a plurality of burst signals. In the third embodiment, as described above, a plurality of series burst signals are multiplied by a steering matrix, and a plurality of series signals multiplied by the steering matrix are transmitted from a plurality of antennas 12.

  According to the embodiment of the present invention, when a rate request signal is output to a wireless device to be communicated, MIMO-LTSs arranged in a plurality of sequences are output while being multiplied by a steering matrix. The data rate information in the wireless device and the data rate information newly generated based on the MIMO-LTS can be acquired, and the accuracy of the information can be improved. Also, by multiplying the various burst formats shown in the first embodiment by a steering matrix, the various burst formats shown in the first embodiment can be transmitted from a plurality of antennas. Even if the number of data is smaller than the number of antennas, data or the like can be transmitted from the plurality of antennas by multiplying the steering matrix. Further, even when the number of data is smaller than the number of antennas, the same effect as when data or the like is transmitted from a plurality of antennas can be obtained by multiplying the steering matrix.

Example 4
The fourth embodiment relates to a burst format applicable to the first to third embodiments. Here, the burst format may be defined as a burst signal output from the antenna as in the first embodiment, or as a burst signal generated by the control unit or the preamble adding unit as in the second or third embodiment. May be. The burst format according to the fourth embodiment is used as a burst signal when transmitting a training signal. The timing at which the burst signal of the burst format should be transmitted is a training request signal as in the first embodiment. Or after transmitting the rate request signal.

  The wireless device 10 according to the fourth embodiment is the same type as the first wireless device 10a of FIG. Here, three types of burst formats will be described. Each of the three types of burst formats is defined as a burst signal output from an antenna as in the first embodiment, or as a burst signal generated by a control unit or a preamble adding unit as in the second or third embodiment. Subdivided when prescribed. Further, it is subdivided according to the timing at which the burst signal is transmitted. Here, the burst format itself will be mainly described. Further, the specific implementation for the subdivision is made based on the description of Examples 1 to 3.

  In the three types of burst formats, when the number of antennas 12 that should transmit MIMO-LTS is larger than the number of antennas 12 that should transmit data, or the number of sequences that arrange MIMO-LTS arranges data. This corresponds to a modification in the case where the number is larger than the number of series. This can be said to be a modification of FIGS. 3B, 19A to 19B, 21A to 21D, and 26A.

  A first modification will be described. Here, a first modification will be described with reference to FIG. In FIG. 19A, the MIMO-LTS is arranged so as to correspond to the first antenna 12a to the third antenna 12c, and the data is arranged so as to correspond to the first antenna 12a and the second antenna 12b. In the modified example, the number of antennas 12 to transmit MIMO-LTS (hereinafter, all or one of these antennas 12 is referred to as “LTS antennas 12”) is the number of antennas 12 to transmit data (hereinafter referred to as such). The present invention relates to the selection of the data antenna 12 when all or one of the large antennas 12 is larger than the number of “data antennas 12”. The subject with respect to this modification is shown as follows. The antenna 12 to which no data is transmitted does not transmit MIMO-STS. Therefore, if the signal strength of the MIMO-LTS transmitted from the antenna 12 is larger on the receiving side than the signal strength of the MIMO-LTS transmitted from the other antenna 12, the received MIMO-LTS is distorted. It becomes easy. For this reason, errors are likely to occur in data, and communication quality is likely to deteriorate.

  The radio apparatus 10 according to the modification measures the strength of the signal received from the radio apparatus 10 to be communicated with each of the plurality of antennas 12 as a unit, as in step 64 of FIG. Here, the measurement of the signal strength is not limited to the MIMO-STS or MIMO-LTS portion of the burst signal, but may be performed at an arbitrary portion of the burst signal. Further, the radio apparatus 10 selects at least one antenna 12 for transmitting data from the plurality of antennas 12 based on the measured signal strength. The selected antenna 12 corresponds to the data antenna 12. For example, the antenna 12 that receives the signals having the first and second magnitudes is selected. More specifically, it is as follows. The radio apparatus 10 measures the strength of signals received from the first antenna 12a to the third antenna 12c. The radio apparatus 10 selects the first antenna 12a and the second antenna 12b according to the magnitude of the measured signal strength. Further, a burst signal in which data is arranged so as to correspond to the selected first antenna 12a and second antenna 12b is generated. Here, the symmetry of the wireless transmission path on the transmission side and the reception side is used.

  The first modification can be combined as follows. The antenna 12 selected for transmitting data may be included in the antenna 12 selected for transmitting the MIMO-LTS in the first embodiment. Therefore, it may be applied to FIGS. 11 and 12. Further, the training signal having the burst format of the modification may be transmitted after receiving the training request signal or transmitting the rate request signal as in the first embodiment. Therefore, the present invention may be applied to FIGS. 4, 5, and 9 to 16. Further, the modified burst format is not defined so as to correspond to the antenna 12 and may be defined in the burst signal generated by the control unit 30 or the preamble adding unit 316 as in the second and third embodiments. . In that case, the transmission function of the radio | wireless apparatus 10 may be the same type as the transmission apparatus 300 of FIG. Further, a steering matrix may be applied as in the transmission device 300 of FIG.

  A second modification will be described. The modification relates to MIMO-LTS transmitted from the antennas 12 other than the data antenna 12 among the LTS antennas 12 when the number of LTS antennas 12 is larger than the number of data antennas 12. The problem for the second modification is also shown in the same manner as the problem for the first modification. In the case of FIG. 19A, among the LTS antennas 12, the antennas 12 other than the data antenna 12 correspond to the third antenna 12c.

  In the modification, the amplitude of the third MIMO-LTS transmitted from the third antenna 12c is defined to be smaller than the amplitude of the first MIMO-LTS and the second MIMO-LTS transmitted from the first antenna 12a and the second antenna 12b. Has been. For example, this corresponds to a case where the amplitude in the third MIMO-LTS is ½ of the amplitude in the first MIMO-LTS and the second MIMO-LTS. The first antenna 12a and the second antenna 12b correspond to the data antenna 12. In the modification, the signal strength of the third MIMO-LTS can be reduced by reducing the amplitude of the third MIMO-LTS transmitted from the third antenna 12c. In addition, when the signal strength of the third MIMO-LTS is reduced, even if no MIMO-STS is added to the third MIMO-LTS, distortion with respect to the MIMO-LTS is less likely to occur. In addition, an accurate transmission path can be estimated by correcting the signal strength of the reduced MIMO-LTS on the receiving side.

  In the second modification, the same combination as in the first modification is possible. That is, it is effective to reduce the amplitude of some MIMO-LTSs as compared to FIGS. 3B, 19A to 19B, and 21A to 21D. Also, the second modification can be applied to FIG. Specifically, a steering matrix may be applied to the second modification. For example, if the second modification is applied to the burst format of FIG. 19A and then the steering matrix is applied, the burst format at that time is shown in FIG.

  A third modification will be described. As in the second modification, the third modification is an antenna other than the data antenna 12 among the LTS antennas 12 when the number of LTS antennas 12 is larger than the number of data antennas 12. 12 is related to MIMO-LTS transmitted from Twelve. The problem for the third modification is also shown in the same manner as the problem for the first modification. In the case of FIG. 19A, among the LTS antennas 12, the antennas 12 other than the data antenna 12 correspond to the third antenna 12c. In the modification, the number of subcarriers used in the third MIMO-LTS transmitted from the third antenna 12c is used in the first MIMO-LTS and the second MIMO-LTS transmitted from the first antenna 12a and the second antenna 12b. The value is defined to be smaller than the number of subcarriers to be processed.

  This corresponds to the case where “52 subcarriers” are used for the first MIMO-LTS and the second MIMO-LTS, but “26 subcarriers” are used for the third MIMO-LTS. The first antenna 12a and the second antenna 12b correspond to the data antenna 12. In the modification, the signal strength of the third MIMO-LTS can be reduced by reducing the number of subcarriers used for the third MIMO-LTS. In addition, when the signal strength of the third MIMO-LTS is reduced, even if no MIMO-STS is added to the third MIMO-LTS, distortion with respect to the MIMO-LTS is less likely to occur. Although a part of subcarriers is not used on the transmitting side, the transmission paths for all subcarriers are estimated by interpolating the transmission paths estimated for the predetermined subcarriers on the receiving side. it can.

  In the third modification, the same combination as in the first modification is possible. That is, it is effective not to use some of the subcarriers in FIGS. 3B, 19A to 19B, and 21A to 21D. In addition, a third modification can be applied to FIG. Specifically, a steering matrix may be applied to the third modification. For example, if the third modification is applied to the burst format of FIG. 19A and then the steering matrix is applied, the burst format at that time is shown in FIG.

  According to the embodiment of the present invention, when an antenna to transmit MIMO-STS and data is determined, an antenna having a high received signal strength is preferentially used, so that a wireless device to be communicated receives a burst signal. When this occurs, the signal strength of MIMO-STS increases to some extent. Therefore, since the AGC is set to have a low gain to some extent, it is possible to reduce the probability of occurrence of MIMO-LTS distortion due to AGC. In addition, since the probability of occurrence of distortion with respect to MIMO-LTS can be reduced, deterioration of the data error rate can be suppressed. Moreover, since the deterioration of the data error rate can be prevented, the deterioration of the communication quality can be suppressed. Also, the transmission path can be estimated accurately. In addition, data transmission efficiency can be improved.

  In addition, since the amplitude of the MIMO-LTS transmitted from an antenna other than the data antenna is made smaller than the amplitude of other MIMO-LTS, the probability of occurrence of distortion with respect to the MIMO-LTS can be reduced on the receiving side. In addition, since the number of subcarriers in the MIMO-LTS transmitted from an antenna other than the data antenna is smaller than the number of subcarriers in the other MIMO-LTS, distortion on the MIMO-LTS occurs on the receiving side. Probability can be reduced. The present invention can also be applied when a steering matrix is used.

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

  In the first embodiment of the present invention, the selection unit 28 preferentially selects the antenna 12 having a high received signal strength. However, the present invention is not limited to this. For example, a delay spread may be derived for each antenna 12 and the antenna 12 having a small delay spread may be preferentially selected. According to this modification, it is possible to preferentially select the antenna 12 that is less affected by the delayed wave. That is, the antenna 12 with good radio quality may be selected with priority.

  In the first embodiment of the present invention, the first radio apparatus 10a has the same number of antennas 12 to be used when transmitting training signals as the number of antennas 12 to be used when receiving training signals. So that it is controlled. However, the present invention is not limited to this, and control may be performed so that they are different, for example. That is, the processing unit 22 receives a training signal for reception from the second radio apparatus 10b by the plurality of antennas 12, and the selection unit 28 transmits at least one of the plurality of antennas 12 to which the training signal should be transmitted. The antenna 12 is selected. At this time, the selection unit 28 may derive radio quality corresponding to each of the plurality of antennas 12 based on the received training signal for reception, and preferentially select the antennas 12 having good radio quality. . According to this modification, the number of transmitting antennas 12 and the number of receiving antennas 12 can be set independently.

  A modification in which the second embodiment and the first embodiment of the present invention are combined is also effective. For example, in the embodiment, the number of a plurality of sequences finally transmitted from the radio unit 20 may be smaller than the number of antennas 12 according to the description of the first embodiment. According to this modification, an effect obtained by combining the first embodiment and the second embodiment can be obtained.

  Any combination of Examples 1 to 4 of the present invention is also effective. According to this modification, the effect which combined these is acquired.

It is a figure which shows the spectrum of the multicarrier signal which concerns on Example 1 of this invention. It is a figure which shows the structure of the communication system which concerns on Example 1 of this invention. FIGS. 3A to 3B are diagrams showing the structure of the burst format in the communication system of FIG. It is a sequence diagram which shows the communication procedure used as the comparison object in the communication system of FIG. It is a sequence diagram which shows another communication procedure used as the comparison object in the communication system of FIG. It is a figure which shows the structure of the 1st radio | wireless apparatus of FIG. It is a figure which shows the structure of the signal of the frequency domain in FIG. It is a figure which shows the structure of the 1st process part of FIG. FIG. 3 is a sequence diagram showing a procedure for setting a data rate in the communication system of FIG. 2. 7 is a flowchart illustrating a procedure for setting a data rate in the first wireless device in FIG. 6. It is a sequence diagram which shows another procedure of the setting of the data rate in the communication system of FIG. 7 is a flowchart showing another procedure for setting a data rate in the first wireless device of FIG. 6. It is a sequence diagram which shows the communication procedure in the communication system of FIG. It is a flowchart which shows the transmission procedure in the 2nd radio | wireless apparatus of FIG. It is a sequence diagram which shows another procedure of the setting of the data rate in the communication system of FIG. FIG. 7 is a flowchart showing yet another procedure for setting a data rate in the first wireless device of FIG. 6. FIG. It is a figure which shows the structure of the control part of FIG. It is a figure which shows the structure of the determination reference | standard memorize | stored in the memory | storage part of FIG. 19A and 19B are diagrams showing another configuration of the burst format in the communication system of FIG. It is a figure which shows another structure of the burst format in the communication system of FIG. FIGS. 21A to 21D are diagrams showing further configurations of the burst format in the communication system of FIG. FIGS. 22A and 22B are diagrams showing the structure of a burst format obtained by modifying the burst format in FIG. It is a flowchart which shows the transmission procedure corresponding to the burst format of Fig.22 (a)-(b). It is a flowchart which shows another transmission procedure corresponding to the burst format of Fig.22 (a)-(b). It is a figure which shows the structure of the transmitter which concerns on Example 2 of this invention. 26 (a)-(b) is a diagram showing a burst format of a burst signal generated in the transmission apparatus of FIG. It is a figure which shows the structure of the burst format which concerns on Example 3 of this invention.

Explanation of symbols

  10 radio apparatus, 12 antenna, 14 antenna, 20 radio section, 22 processing section, 24 modulation / demodulation section, 26 IF section, 28 selection section, 30 control section, 32 rate information management section, 40 FFT section, 42 combining section, 44 A signal generation unit, 46 demultiplexing unit, 48 IFFT unit, 50 preamble addition unit, 52 transmission weight vector calculation unit, 54 reception weight vector calculation unit, 56 multiplication unit, 58 multiplication unit, 60 addition unit, 100 communication system.

Claims (4)

The wireless device to be communicated corresponding to the variable data rate, the first known signal is arranged in at least one of the plurality of antennas, at the subsequent stage of the first known signal, the antenna first known signal is assigned A transmission unit that transmits a burst signal in a first format including a second known signal arranged in the first known signal and data arranged in an antenna where the first known signal is arranged at a subsequent stage of the second known signal ;
A control unit that generates a request signal for causing the wireless device to provide information on a data rate suitable for a wireless transmission path with the wireless device to be communicated, and transmits the request signal from the transmission unit;
When transmitting the request signal, the transmission unit includes a first known signal disposed in at least one of the plurality of antennas and a second disposed in each of the plurality of antennas after the first known signal. a known signal at the subsequent stage of the second known signal, the first known signal is placed in the deployed antenna and Rutotomoni includes including a request signal data, than the number of antennas in which the second known signal is assigned A radio apparatus that transmits a burst signal in the second format in which the number of antennas on which the first known signal is arranged is reduced . The wireless device to be communicated corresponding to the variable data rate, the first known signal is arranged in at least one of the plurality of antennas, at the subsequent stage of the first known signal, the antenna first known signal is assigned Is a transmission method for transmitting a burst signal in the first format including the second known signal arranged in the first known signal and the data arranged in the antenna where the first known signal is arranged at the subsequent stage of the second known signal. And
When generating a request signal for causing the wireless device to provide information on a data rate suitable for the wireless transmission path with the wireless device to be communicated, and transmitting the request signal , at least one of the plurality of antennas The first known signal is arranged at the first stage of the first known signal, the second known signal arranged at each of the plurality of antennas, and the second stage of the second known signal. It was placed on the antenna, and Rutotomoni includes including a request signal data, than the second known signal is the number of antennas that are arranged, in the second format with a reduced number of antennas in which the first known signal is assigned A transmission method characterized by transmitting a burst signal. A first known signal arranged in at least one of a plurality of series and a series in which the first known signal is arranged in the subsequent stage of the first known signal for a wireless device to be communicated corresponding to a variable data rate An output unit for outputting a burst signal in a first format including a second known signal arranged in the first known signal and data arranged in a sequence in which the first known signal is arranged in a subsequent stage of the second known signal ;
A control unit that generates a request signal for causing the wireless device to provide information on a data rate suitable for a wireless transmission path with a wireless device to be communicated, and outputs the request signal from the output unit;
When transmitting the request signal, the output unit includes a first known signal arranged in at least one of the plurality of series and a second stage arranged in each of the plurality of series at a subsequent stage of the first known signal. a known signal at the subsequent stage of the second known signal, the first known signal is placed in the arranged sequence, and includes containing the request signal data Rutotomoni, than the number of series second known signal is assigned A radio apparatus that outputs a burst signal in the second format in which the number of sequences in which the first known signal is arranged is reduced . A first known signal arranged in at least one of a plurality of series and a series in which the first known signal is arranged in the subsequent stage of the first known signal for a wireless device to be communicated corresponding to a variable data rate Is a transmission method for transmitting a burst signal in a first format including a second known signal arranged in the first known signal and data arranged in a sequence in which the first known signal is arranged in a subsequent stage of the second known signal. And
When generating a request signal for causing the wireless device to provide information on a data rate suitable for a wireless transmission path with the wireless device to be communicated, and transmitting the request signal , at least one of a plurality of sequences The first known signal is arranged in a stage after the first known signal arranged in one, the second known signal arranged in each of the plurality of sequences, and the latter stage in the second known signal. It was placed in series, and Rutotomoni includes including a request signal data, than the second known signal is the number of series arranged, in the second format with a reduced number of sequences first known signal is assigned A transmission method characterized by transmitting a burst signal.

Images