JP2008085922A - Multi-antenna transmission apparatus, multi-antenna transmission method and receiving apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a multi-antenna transmission apparatus, a multi-antenna transmission method and a receiving apparatus, which can perform multi-antenna transmission even with a broadband signal such as a pulse-based modulated signal and improve a transmission rate of the broadband signal. <P>SOLUTION: A control section 109 carries out switching control of an antenna for transmitting a modulated signal 103 in accordance with transmission data 101. By so doing, it becomes possible to estimate an antenna to which the modulated signal has been transmitted by use of a difference of multipath environments for each of transmission antennas 108A-108D. Therefore, it is possible to perform multi-antenna transmission by making effective use of delayed waves that have been the cause of deterioration of reception quality in broadband transmission. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a multi-antenna transmission apparatus, a multi-antenna transmission method, and a reception apparatus, and more particularly to a technique for transmitting a pulse-based modulation signal, which is a kind of UWB (Ultra Wide Band) signal, using a plurality of antennas.

  Conventionally, a configuration as shown in FIG. 30 is known as a technique for transmitting a pulse-based modulated signal using a plurality of antennas (see, for example, Non-Patent Document 1).

  In FIG. 30, the transmission apparatus 20 inputs transmission data 1A and 1B to pulse-based modulation signal generation units 2A and 2B, respectively. The pulse-based modulation signal generators 2A and 2B generate pulse-based modulation signals 3A and 3B corresponding to the transmission data 1A and 1B, and output them. The filters 4A, 4B receive the pulse-based modulation signals 3A, 3B, band-limit them, and supply them to the antennas 5A, 5B. Thereby, the pulse-based modulation signals 3A and 3B are transmitted as radio waves from the antennas 5A and 5B.

  The receiving device 30 receives the combined wave of the two modulated signals transmitted from the antennas 5A and 5B of the transmitting device 20 by the antennas 6X and 6Y. Received signal 9X filtered by filter 8X is sent to channel estimation unit 10X and MMSE (Minimum Mean Squared Error) processing unit 12, and received signal 9Y filtered by filter 8Y is sent to channel estimation unit 10Y and MMSE processing unit 12. Is done.

  The channel estimation units 10X and 10Y receive the received signals 9X and 9Y, respectively, detect, for example, known symbols included in the received signals 9X and 9Y, estimate channel fluctuations based on the detected known symbols, and estimate channel fluctuations. Signals 11X and 11Y are output.

  The MMSE processing unit 12 receives the received signals 9X and 9Y and the channel fluctuation estimation signals 11X and 11Y, and executes a MMSE algorithm to separate the combined signal multiplexed in space, and generates a pulse-based modulated signal 3A, Modulation signals 13A and 13B corresponding to 3B are obtained.

The demodulation units 14A and 14B receive the pulse-based modulation signals 13A and 13B, respectively, and demodulate them to obtain reception data 15A and 15B.
“MMSE Detection for High Data Rate UWB MIMO Systems” in Proceeding of IEEE VTC2004 fall, pp.1463-1467, 2004

  By the way, when a wideband signal such as a UWB signal is transmitted in a MIMO (Multiple-Input Multiple-Output) communication system as in Non-Patent Document 1, the influence of delay waves is large as in a multipath environment. The error rate characteristics of received data obtained on the receiving side deteriorate. That is, since intersymbol interference occurs, reception quality deteriorates.

  As described above, in order to increase the data transmission speed of a wideband signal such as a pulse-based modulation signal, it is actually difficult to use the conventional MIMO reception technique even if the multi-antenna communication technique is applied. There is.

  The present invention has been made in view of the above points, and enables multi-antenna transmission even with a wide-band signal such as a pulse-based modulation signal, and improves the transmission speed of the wide-band signal, and multi-antenna transmission. It is an object to provide a method and a receiving apparatus.

  In other words, the present invention is not limited to a signal such as an OFDM signal or a spread spectrum signal that has conventionally been capable of multi-antenna communication even in an environment where the influence of delayed waves is large, that is, without being constrained by the modulation scheme of the transmission signal. An object of the present invention is to provide a multi-antenna transmission apparatus, a multi-antenna transmission method, and a reception apparatus that can perform multi-antenna communication even in an environment where the influence of delay waves is large.

  The multi-antenna transmission apparatus of the present invention includes a plurality of antennas, UWB signal generation means for generating a UWB signal based on transmission data, and a UWB signal generated by the UWB signal generation unit among the plurality of antennas. A configuration is provided that includes transmission antenna control means for switching and controlling a transmitting antenna according to the transmission data.

  Moreover, the multi-antenna transmission method of the present invention includes a UWB signal generation step for generating a UWB signal based on transmission data, and an antenna for transmitting the UWB signal generated in the UWB signal generation step among a plurality of transmission antennas. And a transmission antenna control step of performing switching control according to the transmission data.

  According to this configuration and method, since the reception waveform differs greatly (low correlation) depending on which transmission antenna the UWB signal is transmitted from, the reception side performs transmission using which transmission antenna based on the reception waveform. It is easy and accurate to identify Here, the transmission antenna control means (transmission antenna control step) performs transmission control in which the antenna to be transmitted and transmission data are associated with each other. Therefore, on the reception side, the transmission antenna identified as having been transmitted. Based on, transmission data (reception data) associated with the transmission antenna can be obtained.

  Thus, according to the present invention, multi-antenna transmission of a broadband signal such as a UWB signal is possible, and the transmission rate of the broadband signal can be improved.

  The inventors of the present invention show that in wideband signals such as pulse-based modulated signals, the signal correlation between the transmitting antennas is low at the time of reception, which means that the independence of signals between the transmitting antennas is strong at the time of reception. Focusing on the meaning, the present invention was reached by actively using it.

  In the present invention, first, a wideband signal is transmitted from each transmission antenna at a different time, and a reception waveform of the wideband signal transmitted from each transmission antenna is stored for each transmission antenna on the reception side. This received waveform has low correlation (that is, high independence) between the transmission antennas. After this preprocessing, data transmission is started from the multi-antenna transmission apparatus. At this time, the multi-antenna transmission apparatus performs switching control of the antenna that transmits the broadband signal according to the transmission data. For example, when transmitting data “1”, a wideband signal is transmitted from the first transmission antenna, and when transmitting data “0”, a wideband signal is transmitted from the second transmission antenna. That is, the data is determined depending on from which transmission antenna the broadband signal is transmitted.

  On the reception side, the reception waveform of the wideband signal transmitted from the first transmission antenna and the reception waveform of the wideband signal transmitted from the second transmission antenna are greatly different, and therefore based on the reception waveform stored in advance. Thus, it can be accurately determined from which transmission antenna the signal is currently transmitted. Accordingly, it can be determined whether data “1” is transmitted or data “0” is transmitted.

  As described above, one feature of the present invention is that when a wideband signal is transmitted by multi-antenna, it is effectively utilized that the received waveform is greatly different (strong independence) depending on which antenna the signal is transmitted from. This enables multi-antenna transmission of a wideband signal and improves the transmission speed of the wideband signal.

  In addition, one feature of the present invention is that the transmission antenna is switched and controlled so that the relationship between the antenna arrangement and the bit of the transmission data is a gray coding relationship. As a result, it is possible to further improve the error rate characteristics of received data on the receiving side.

  Furthermore, in the present invention, when performing multi-antenna transmission, various measures have been taken to improve the error rate characteristics of received data while enabling high-speed data transmission. These ideas will be described in detail in the following embodiments.

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

(Embodiment 1)
FIG. 1 shows a configuration example of a transmission apparatus according to Embodiment 1 of the present invention. The transmission apparatus 100 inputs the transmission data 101 to the pulse-based modulation signal generation unit 102 and the control unit 109.

  The pulse-based modulation signal generation unit 102 generates a pulse-based modulation signal 103 based on the transmission data 101, and sends this to the on / off switches 104A to 104D provided corresponding to the antennas 108A to 108D. Specifically, the pulse-based modulation signal generation unit 102 generates a pulse-based modulation signal 103 having different pulse positions, pulse phases, amplitudes, and the like in one symbol period according to the transmission data 101.

  The control unit 109 generates a frame configuration signal 110 and sends it to the on / off switches 104A to 104D. The control unit 109 refers to the transmission data 101 when generating the frame configuration signal 110. Details of the frame configuration signal 110 and transmission control by the frame configuration signal 110 will be described in detail later.

  Each of the on / off switches 104A to 104D is on / off controlled based on the frame configuration signal 110. When the on / off switches 104A to 104D are on controlled, the pulse-based modulation signal 103 is output as the modulation signals 105A to 105D.

  Each of the filters 106A to 106D receives the pulse-based modulation signals 105A to 105D, performs band limitation, and transmits the band-limited pulse-based modulation signals 107A to 107D to the antennas 108A to 108D.

  FIG. 2 shows a frame configuration example of the modulated signal transmitted by the transmission apparatus 100. The horizontal axis indicates time. Transmitting apparatus 100 transmits a modulated signal having a frame configuration as shown in FIG. 2 from antenna 108A, antenna 108B, antenna 108C, and antenna 108D. In the figure, the antenna 108A is abbreviated as the antenna A, the antenna 108B as the antenna B, the antenna 108C as the antenna C, and the antenna 108D as the antenna D.

  At time 0, the transmission apparatus 100 transmits a synchronization symbol for the reception apparatus to acquire signal detection, time, and frequency synchronization from all the antennas 108A to 108D. That is, at time 0, all the on / off switches 104A to 104D are on-controlled.

  At time 1, a pilot symbol for estimating channel fluctuation is transmitted from the receiving apparatus only from antenna 108A (a pulse is transmitted). On the other hand, a guard symbol is transmitted from antenna 108B, antenna 108C, and antenna 108D (a pulse is not transmitted). That is, at time 1, only the on / off switch 104A is on-controlled.

  At time 2, pilot symbols are transmitted (pulses are transmitted) only from antenna 108B. On the other hand, a guard symbol is transmitted (no pulse is transmitted) from antenna 108A, antenna 108C, and antenna 108D. That is, at time 2, only the on / off switch 104B is on-controlled.

  At time 3, pilot symbols are transmitted (pulses are transmitted) only from antenna 108C. On the other hand, a guard symbol is transmitted from the antenna 108A, antenna 108B, and antenna 108D (no pulse is transmitted). That is, at time 3, only the on / off switch 104C is on-controlled.

  At time 4, pilot symbols are transmitted (pulses are transmitted) only from antenna 108D. On the other hand, a guard symbol is transmitted from antenna 108A, antenna 108B, and antenna 108C (a pulse is not transmitted). That is, at time 4, only the on / off switch 104D is on-controlled.

  From time 5 to time 9, data symbols are transmitted. This data symbol transmission control will be described later.

  FIG. 3 shows an image of a signal transmitted from time 1 to time 4 in the antenna 108A. In FIG. 3B, the horizontal axis time and the vertical axis amplitude. At time 1, a pulse is transmitted, but at other times 2 to 4, no pulse is transmitted. The signals transmitted from the antenna 108B, the antenna 108C, and the antenna 108D also have similar waveforms except that the time for transmitting the pilot symbol (pulse) is different.

  In this way, the pilot symbols transmitted from the antennas 108A to 108D can be received without interference by the receiving device.

  Next, transmission control of data symbols transmitted from time 5 to time 9 will be described in detail with reference to FIG.

  In FIG. 4, the horizontal axis is time, and data of 2 bits per unit period such as “00” at time 5, “01” at time 6, “10” at time 7, and “11” at time 8. Is transmitted (FIG. 4A).

  In this embodiment, an antenna (an antenna indicated by “ON” in the figure) that transmits a pulse is changed according to a bit to be transmitted.

  In the case of FIG. 4, at time 5, in order to transmit 2-bit data of “00”, a pulse is transmitted only from the antenna A (“ON”), and no pulse is transmitted from other antennas (“ OFF ”). Similarly, at time 6, in order to transmit 2-bit data of “01”, a pulse is transmitted only from the antenna B (“ON”), and a pulse is not transmitted from other antennas (“OFF”). At time 7, in order to transmit 2-bit data of “10”, a pulse is transmitted only from the antenna C (“ON”), and no pulse is transmitted from other antennas (“OFF”). At time 8, in order to transmit 2-bit data of “11”, a pulse is transmitted only from the antenna D (“ON”), and no pulse is transmitted from other antennas (“OFF”). FIG. 4B is a diagram illustrating waveforms of signals transmitted from the respective antennas when the horizontal axis time and the vertical axis amplitude are set from time 5 to time 8.

  In this way, by switching control of the antenna that transmits the pulse-based modulation signal according to the bit to be transmitted, it is possible to identify which data has been transmitted on the receiving side. This is because, as described above, a pulse-based modulated signal has a greatly different reception waveform (strong independence) depending on which antenna the signal is transmitted from. This is because the transmitted pulse can be identified and the bit assigned to the transmitting antenna can be used as received data.

  If the transmission method of this Embodiment is used, since the number of bits allocated to a transmission antenna can be increased, so that the number of transmission antennas is increased, the data amount which can be transmitted per time can be increased. In addition, since the independence of the reception waveform of each transmission antenna by multipath is actively utilized, there is generally no adverse effect due to multipath, which is a cause of deterioration in reception quality. That is, it can be said that the transmission method of the present embodiment is more effective in a multipath environment.

  FIG. 5 shows a configuration example of the receiving apparatus in this embodiment. The receiving device 500 receives and demodulates the signal transmitted from the transmitting device 100. The receiving apparatus 500 inputs the received signal 502 received by the receiving antenna 501 to the filter 503. The filter 503 sends the received signal 504 after filtering to the demodulator 505. Demodulation section 505 obtains received data 506 by demodulating received signal 504.

  FIG. 6 shows a configuration example of the demodulation unit 505. Demodulation section 505 inputs received signal 504 to synchronization section 602, waveform storage sections 604A to 604D, and correlation calculation sections 606A to 606D.

  The synchronization unit 602 detects the synchronization symbol shown in FIG. 2 included in the received signal 504, performs time synchronization and frequency synchronization based on the synchronization symbol, and transmits a control signal 603 for these synchronizations to the waveform storage unit. 604A to 604D, correlation calculation units 606A to 606D, and determination unit 608.

  The waveform storage unit 604A extracts the received waveform of the pilot symbol transmitted from the antenna A of FIG. 2 from the received signal 504 at the timing based on the control signal 603, stores this, and receives the stored pilot symbol. The waveform signal 605A is sent to the correlation calculation unit 606A. Similarly, the waveform storage unit 604B extracts the received waveform of the pilot symbol transmitted from the antenna B of FIG. 2 from the received signal 504 at the timing based on the control signal 603, stores this, and stores the stored pilot. The symbol reception waveform signal 605B is sent to the correlation calculation unit 606B. Similarly, the waveform storage unit 604C extracts the received waveform of the pilot symbol transmitted from the antenna C in FIG. 2 from the received signal 504 at the timing based on the control signal 603, stores this, and stores the stored pilot. The symbol reception waveform signal 605C is sent to the correlation calculation unit 606C. Similarly, the waveform storage unit 604D extracts the received waveform of the pilot symbol transmitted from the antenna D of FIG. 2 from the received signal 504 at the timing based on the control signal 603, stores this, and stores the stored pilot. The symbol reception waveform signal 605D is sent to the correlation calculation unit 606D.

  Correlation calculation section 606A obtains correlation value signal 607A by performing correlation calculation between reception signal 504 and reception waveform signal 605A of the pilot symbol transmitted from antenna A. Similarly, correlation calculation section 606B obtains correlation value signal 607B by performing correlation calculation between received signal 504 and received waveform signal 605B of the pilot symbol transmitted from antenna B. Similarly, correlation calculation section 606C obtains correlation value signal 607C by performing correlation calculation between received signal 504 and received waveform signal 605C of the pilot symbol transmitted from antenna C. Similarly, correlation calculation section 606D obtains correlation value signal 607D by performing correlation calculation between reception signal 504 and reception waveform signal 605D of the pilot symbol transmitted from antenna D.

  The determination unit 608 compares the magnitudes of the correlation value signals 607A, 607B, 607C, and 607D at the timing based on the control signal 603 (specifically, for each data symbol period), and the correlation value having the largest value. The signal is detected, it is determined that a pulse is transmitted from the transmission antenna corresponding to the correlation value signal, and the bits assigned to the transmission antenna are output as reception data 506. For example, if the correlation value signal 607A has the largest value in a certain data symbol period, it is determined that a pulse-based modulation signal is transmitted from the antenna A, and the antenna A is connected to the antenna A as shown in FIG. The assigned bit “00” is output as received data 506.

  The correlation calculation unit 606A and the determination unit 608 in FIG. 6 will be described in more detail with reference to FIGS.

  In FIG. 7, the modulated signals of the pulse-based modulated signals transmitted from the transmitting antennas 108 </ b> A to 108 </ b> D reach the receiving antenna 501 after being affected by different propagation environments. At this time, in particular, as in this embodiment, a UWB (Ultra Wide Band) system that transmits a pulse-based modulated signal is greatly affected by multipath. In addition, how to be affected by the multipath greatly differs for each of the transmission antennas 108A to 108D due to the antenna arrangement. The present invention effectively utilizes this point.

  In FIG. 2, since the pilot signal is transmitted only from antenna A at time 1, the waveform obtained at time 1 in the receiving apparatus is a waveform in which the modulated signal transmitted from antenna A is affected by propagation ( FIG. 7 (a)). Similarly, since the pilot signal is transmitted only from antenna B at time 2, the waveform obtained at time 2 in the receiving apparatus is a waveform in which the modulated signal transmitted from antenna B is affected by propagation (FIG. 7 (b)). Similarly, since the pilot signal is transmitted only from antenna C at time 3, the waveform obtained at time 3 in the receiving device is a waveform in which the modulated signal transmitted from antenna C is affected by propagation (FIG. 7 (c)). Similarly, since the pilot signal is transmitted only from antenna D at time 4, the waveform obtained at time 4 in the receiving apparatus is a waveform in which the modulated signal transmitted from antenna D is affected by propagation (FIG. 7 (d)).

  Here, the waveform in FIG. 7A is stored in the waveform storage unit 604A in FIG. 6, the waveform in FIG. 7B is stored in the waveform storage unit 604B, and the waveform in FIG. 7C is stored in the waveform storage unit 604C. And the waveform of FIG. 7D is stored in the waveform storage unit 604D.

  That is, waveforms as shown in FIG. 8A are stored in the waveform storage units 604A to 604D (simply abbreviated as waveform storage units A to D in the figure) in FIG. FIG. 8B shows an example of the reception waveform of the data symbol at time 5 in FIG.

  Here, for example, it is assumed that a modulated signal is transmitted from the antenna A to transmit “00” data as shown in FIG. Then, on the receiving side, a waveform close to FIG. 7A is received at time 5 (see FIG. 8B).

  In this case, as shown in FIG. 6, when the correlation calculation between the received signal and the stored waveform is performed, there is a high possibility that the correlation value with the waveform storage unit A will be the largest value. Therefore, the determination unit 608 in FIG. 6 may determine data (in this case, “00”) corresponding to a highly correlated signal as the reception data 506.

  As described above, according to the present embodiment, by switching and controlling the antenna that transmits the pulse-based modulation signal in accordance with the bit to be transmitted, a multiband of a wideband signal such as the pulse-based modulation signal can be obtained. Antenna transmission is possible, and an improvement in transmission rate commensurate with the increase in the number of transmission antennas can be achieved.

  On the receiving side, the antenna that transmitted the modulated signal is estimated using the difference in the multipath environment for each antenna. It is possible to obtain received data with good error rate characteristics by effectively utilizing waves.

  Next, a method capable of obtaining received data with even better error rate characteristics will be presented. The method is to apply gray coding to the bit allocation to the transmission antenna in consideration of the arrangement of the transmission antenna.

  9 and 10 show an example of the relationship between the installation positions of the transmission antennas AN_A to AN_D of the transmission apparatus according to the present embodiment and the assignment of transmission bits to the transmission antennas AN_A to AN_D.

  Consider a case where transmission antennas AN_A to AN_D are linearly arranged as shown in FIG. In this case, the smaller the distance between the antennas, the higher the possibility that the antenna correlation (reception waveform correlation) increases. For example, the antenna correlation between the transmission antenna AN_A and the transmission antenna AN_B is larger than the antenna correlation between the transmission antenna AN_A and the transmission antenna AN_D. In consideration of this, in the present embodiment, different bit allocation is performed between transmission antennas that are farther away. For example, in FIG. 9, only one bit out of two bits differs between adjacent transmit antennas (AN_A and AN_B, AN_B and AN_D, and AN_D and AN_C), whereas every other transmit antenna (AN_A and AN_D). , AN_B and AN_C) have bit assignments such that all two bits are different.

  Similarly, when the transmission antennas AN_A to AN_D are arranged in a square shape as shown in FIG. 10, different allocation of bits is performed between transmission antennas that are farther away. For example, in FIG. 10, only one bit out of two bits differs between adjacent transmit antennas (AN_A and AN_B, AN_B and AN_D, AN_D and AN_C), whereas between transmit antennas on a diagonal line (AN_A and AN_D, In AN_B and AN_C), bit allocation is performed such that all two bits are different.

  As described above, the gray coding is applied to the bit allocation to the transmission antenna in consideration of the magnitude of the antenna correlation depending on the transmission antenna arrangement. In other words, the antenna to be transmitted is controlled so that the relationship between the arrangement of the plurality of transmission antennas and the bit of the transmission data is a gray coding relationship. Thereby, the bit error rate at the time of reception can be reduced.

  For example, consider a case where a modulated signal is transmitted from the transmission antenna 108A (corresponding to the transmission antenna AN_A in FIGS. 9 and 10) at time 5 in FIG. In the receiving apparatus, the correlation is obtained as shown in FIG. 8 to estimate from which transmission antenna the modulated signal is transmitted. Here, in the case of the antenna arrangement as shown in FIG. 9, there is a possibility that the receiving apparatus makes a determination error that the transmitting antenna AN_B, which is an antenna having a high correlation with the transmitting antenna AN_A, transmits, and other transmitting antennas AN_D and AN_C It is higher than the possibility of making a judgment error when transmitted. However, the bit assigned to the transmission antenna AN_B that is likely to cause a determination error is “01”, which is different from the bit “00” assigned to the transmission antenna AN_A by one bit. Therefore, since the possibility that all 2 bits are erroneous can be reduced, the error rate characteristic of the received data can be improved by this amount.

  In the above-described embodiment, the receiving apparatus 500 having one receiving antenna 501 has been described as an example. However, the receiving apparatus is provided with a plurality of receiving antennas, and received data is received based on received signals from the plurality of antennas. You may make it obtain. Hereinafter, an example of the configuration will be described.

  FIG. 11 shows a configuration example of a receiving apparatus having a plurality of antennas 501X and 501Y. Receiving device 1100 inputs received signals 502X and 502Y received by receiving antennas 501X and 501Y to filters 503X and 503Y, respectively. The filters 503X and 503Y send the received signals 504X and 504Y after filtering to the demodulation units 505X and 505Y, respectively.

  Each of the demodulation units 505X and 505Y has a configuration obtained by removing the determination unit 608 from the demodulation unit 505 illustrated in FIG. The demodulator 505X outputs a correlation value signal group 1102X. The demodulator 505Y outputs a correlation value signal group 1102Y. The correlation value signal group 1102X includes 607A_X to 607D_X corresponding to the correlation values 607A to 607D in FIG. Similarly, the correlation value signal group 1102Y includes 607A_Y to 607D_Y corresponding to the correlation values 607A to 607D in FIG.

  The combination determination unit 1103 receives the correlation value signal groups 1102X and 1102Y, combines them, and determines them to obtain received data 1104.

  FIG. 12 shows a configuration example of the composition determination unit 1103. The correlation value signal 607A_X, the correlation value signal 607B_X, the correlation value signal 607C_X, and the correlation value signal 607D_X correspond to the correlation value signal group 1102X in FIG. 11, and the correlation value signal 607A_Y, correlation value signal 607B_Y, correlation value signal 607C_Y, correlation value The signal 607D_Y corresponds to the correlation value signal group 1102Y in FIG.

  Adder 1201A receives correlation value signals 607A_X and 607A_Y related to transmission antenna A as inputs, and adds these to obtain added correlation value signal 1202A. Similarly, the addition unit 1201B receives the correlation value signals 607B_X and 607B_Y related to the transmission antenna B and adds them to obtain an addition correlation value signal 1202B. Similarly, the addition unit 1201C receives the correlation value signals 607C_X and 607C_Y related to the transmission antenna C and adds them to obtain an addition correlation value signal 1202C. Similarly, the addition unit 1201D receives the correlation value signals 607D_X and 607D_Y related to the transmission antenna D and adds them to obtain an addition correlation value signal 1202D. The addition correlation value signals 1202A to 1202D obtained by the addition units 1201A to 1201D are sent to the determination unit 1203.

  The determination unit 1203 compares the magnitudes of the input addition correlation value signals 1202A, 1202B, 1202C, and 1202D, detects the addition correlation value signal having the largest value, and modulates from the transmission antenna corresponding to the correlation value signal It is determined that the signal has been transmitted, and the bits assigned to the transmission antenna are output as received data 1104.

  In this way, in the receiving apparatus, if the number of receiving antennas is increased, the correlation values obtained in the respective receiving antenna branches are combined, and it is determined independently from which transmitting antenna the modulated signal is transmitted based on the combined result. Therefore, the diversity gain increases and the independence of channel fluctuation for each modulated signal is likely to be ensured in the receiver (reduction of antenna correlation, independence of channel fluctuation). Secure). As a result, the antenna to which the modulated signal is transmitted can be determined more accurately, and the data error rate characteristic can be further improved.

  As described above, according to the present embodiment, the transmission side controls switching of the antenna that transmits the modulated signal according to the transmission data, and the antenna on which the modulated signal is transmitted is set for each antenna on the receiving side. Estimated using the difference of multipath environment. Thereby, the data transmission speed can be improved as the number of transmission antennas is increased. In addition, it is possible to obtain received data with good error rate characteristics by effectively utilizing the delayed wave that was the cause of the deterioration of the reception quality.

  In the above-described embodiment, the pulse base modulation signal generation unit 102 common to all the antennas 108A to 108D is provided, and the on / off switches 104A to 104D corresponding to the antennas 108A to 108D are provided. Although the case where the antenna which transmits a pulse is selected by switching control of the on / off switches 104A to 104D has been described, the present invention is not limited to this. For example, a pulse-based modulated signal is generated for each antenna 108A to 108D. And a pulse generation operation of each pulse-based modulation signal generation unit may be controlled on and off according to transmission data. In short, among the plurality of antennas, the antenna that transmits the pulse-based modulation signal generated by the pulse-based modulation signal generation unit may be controlled according to the transmission data.

  In the present embodiment, a transmission apparatus having four transmission antennas has been described as an example. However, the present invention is not limited to this. As the number of transmission antennas is increased, the number of bits that can be allocated to each antenna can be increased, so that the data transmission rate can be increased accordingly. For example, if 8 transmission antennas are provided, 3 bits of data can be transmitted in 1 symbol, and if 16 antennas are provided, 4 bits of data can be transmitted in 1 symbol. Become.

  In this embodiment, the case where the number of transmission antennas is two and the number of reception antennas is one or two has been described as an example. However, the present invention is not limited to this, and data transmission increases as the number of transmission antennas increases. As the number of reception antennas is increased, the reception quality of data is improved.

  Furthermore, in this embodiment, the case where a pulse-based modulation signal is transmitted has been described as an example in which the effect of the present invention is particularly noticeable. However, the present embodiment is applicable to the case where a modulation signal other than a pulse-based modulation signal is transmitted. May be. For example, the present invention may be applied to a general communication system in which orthogonal modulation is performed using a carrier wave on the transmission side and orthogonal demodulation is performed on the reception side. Even in this case, similarly to the above-described embodiment, it is possible to obtain an effect of obtaining received data with good error rate characteristics by effectively utilizing the delayed wave that has caused the deterioration of the reception quality.

  In short, the present invention transmits a modulated signal that lowers the correlation of the received waveform between the transmission antennas, or in a propagation environment where the correlation of the received waveform is lower between the transmission antennas (for example, multipath). The present invention is widely applicable when a modulated signal is transmitted under an environment.

(Embodiment 2)
In Embodiment 1, 2 ² = 4 transmission antennas are provided to transmit 2 bits per unit time (per symbol). However, in the present embodiment, the same number of bits is reduced. A transmitting apparatus capable of transmitting by the number of transmitting antennas is presented.

  FIG. 13 in which the same reference numerals are assigned to the parts corresponding to those in FIG. 1 shows a configuration example of the transmission apparatus according to the present embodiment. The transmission apparatus 1300 has three transmission antennas 108A to 108C and transmission control by the control unit 1301 is different from the transmission apparatus 100 of FIG.

  FIG. 14 shows a frame configuration example of a modulated signal transmitted by transmitting apparatus 1300. The horizontal axis indicates time. Transmitting apparatus 1300 transmits a modulated signal having a frame configuration as shown in FIG. 14 from antenna 108A, antenna 108B, and antenna 108C, respectively. In the figure, antenna 108A is abbreviated as antenna A, antenna 108B is abbreviated as antenna B, and antenna 108C is abbreviated as antenna C.

  At time 0, transmitting apparatus 1300 transmits a synchronization symbol from all antennas 108A to 108C for the receiving apparatus to acquire signal detection, time, and frequency synchronization. That is, at time 0, all the on / off switches 104A to 104C are on-controlled.

  At time 1, pilot symbols for estimating channel fluctuations are transmitted from the antennas 108A and 108B (pulses are transmitted). On the other hand, a guard symbol is transmitted from the antenna 108C (a pulse is not transmitted). That is, at time 1, the on / off switches 104A and 104B are on-controlled.

  At time 2, pilot symbols are transmitted (pulses are transmitted) from antennas 108A and 108C. On the other hand, a guard symbol is transmitted from antenna 108B (no pulse is transmitted). That is, at time 2, the on / off switches 104A and 104C are on-controlled.

  At time 3, pilot symbols are transmitted (pulses are transmitted) from antennas 108B and 108C. On the other hand, a guard symbol is transmitted from antenna 108A (a pulse is not transmitted). That is, at time 3, the on / off switches 104B and 104C are on-controlled.

  At time 4, pilot symbols are transmitted (pulses are transmitted) from all antennas 108A, 108B, and 108C. That is, at time 4, all on / off switches 104A, 104B, and 104C are on-controlled.

  From time 5 to time 9, data symbols are transmitted. The transmission control of data symbols transmitted from time 5 to time 9 will be described in detail with reference to FIG.

  In FIG. 15, the horizontal axis is time, and data of 2 bits per unit time such as “00” at time 5, “01” at time 6, “10” at time 7, and “11” at time 8 Is transmitted (FIG. 15A).

  As can be seen from FIG. 15A, in the present embodiment, as in the first embodiment, the antenna that transmits the pulse (the antenna indicated by “ON” in the figure) is changed according to the bit to be transmitted. It has become. The difference from the first embodiment is that not only one antenna is selected as an antenna that transmits a modulated signal at the same time, but a plurality of antennas are selected as antennas that transmit a modulated signal at the same time. . Specifically, the combination of antennas that transmit modulated signals at the same time is changed according to the transmission bits.

  For example, at time 5, in order to transmit 2-bit data of “00”, a pulse is transmitted from antenna A and antenna B (“ON”), and a pulse is not transmitted from antenna C (“OFF”). Similarly, at time 6, in order to transmit 2-bit data of “01”, a pulse is transmitted from antenna A and antenna C (“ON”), and a pulse is not transmitted from antenna B (“OFF”). . At time 7, in order to transmit 2-bit data of “10”, a pulse is transmitted from antenna B and antenna C (“ON”), and a pulse is not transmitted from antenna A (“OFF”). At time 8, in order to transmit 2-bit data of “11”, a pulse is transmitted from antenna A, antenna B, and antenna C (“ON”).

  FIG. 15B is a diagram showing waveforms of signals transmitted from the respective antennas when the horizontal axis time and the vertical axis amplitude are set from time 5 to time 8.

  As the overall configuration of the receiving apparatus that receives and demodulates the signal transmitted from the transmitting apparatus 1300, the configuration illustrated in FIG. 5 described in Embodiment 1 may be used. However, the receiving apparatus of this embodiment is different from that of Embodiment 1 in the configuration of demodulation section 505.

  FIG. 16, in which parts corresponding to those in FIG. 6 are assigned the same reference numerals, shows the configuration of the demodulation unit of the present embodiment.

  The waveform storage unit 604AB extracts and stores the combined received waveform of the pilot symbols transmitted from the antenna A and the antenna B at time 1 in FIG. 14 and stores them, and also correlates the stored received waveform signal 605AB of the pilot symbols. It is sent to the calculation unit 606AB.

  Similarly, waveform storage section 604AC extracts the combined received waveform of pilot symbols transmitted from antenna A and antenna C at time 2 in FIG. 14, stores this, and stores the combined received waveform signal of the stored pilot symbols. 605AC is sent to the correlation calculation unit 606AC.

  Similarly, waveform storage section 604BC extracts and stores the combined received waveform of pilot symbols transmitted from antenna B and antenna C at time 3 in FIG. 14, and stores this, and also stores the combined received waveform signal of the stored pilot symbols. 605BC is sent to the correlation calculation unit 606BC.

  Similarly, the waveform storage unit 604ABC extracts a combined reception waveform of pilot symbols transmitted from the antenna A, the antenna B, and the antenna C at time 4 in FIG. 14, stores the received waveform, and combines the stored pilot symbols. Received waveform signal 605ABC is sent to correlation calculation unit 606ABC.

  Correlation calculation sections 606AB, 606AC, 606BC, and 606ABC perform correlation calculation between the received signals of the stored pilot symbols and the received signals, similarly to Embodiment 1, to thereby generate correlation value signals 607AB, 607AC, and 607BC. , 607ABC are obtained and sent to the determination unit 608.

  The determination unit 608 compares the magnitudes of the correlation value signals 607AB, 607AC, 607BC, and 607ABC at the timing based on the control signal 603 (specifically, for each data symbol period), and the correlation value having the largest value. A signal is detected, it is determined that a pulse is transmitted from a plurality of transmission antennas corresponding to the correlation value signal, and bits assigned to the combination of the transmission antennas are output as reception data 506. For example, when the correlation value signal 607AB has the largest value in a certain data symbol period, it is determined that a pulse-based modulated signal is transmitted from the antenna A and the antenna B, and as shown in FIG. Bit “00” assigned to the combination of antenna A and antenna B is output as received data 506.

  According to the present embodiment, a combined reception waveform of modulated signals transmitted simultaneously from a plurality of transmission antennas is stored in advance for each combination of transmission antennas transmitted simultaneously, and when a data symbol is transmitted, The received waveform of the data symbol is detected as to which of the previously stored composite received waveforms has the highest correlation, and the bit assigned to the combination of the transmitting antennas having the highest correlation is used as the received data. As a result, the number of transmission antenna selection patterns (transmission antenna patterns to which bits are assigned) increases, so that the same effect as in the first embodiment can be realized with a smaller number of transmission antennas than in the first embodiment. Of course, if the same number of transmission antennas as in the first embodiment are provided, the data transmission rate can be improved as compared with the first embodiment.

  In the above-described embodiment, the pulse base modulation signal generation unit 102 common to all the antennas 108A to 108C is provided, and the on / off switches 104A to 104C corresponding to the antennas 108A to 108C are provided. Although the case where the antenna which transmits a pulse is selected by switching control of the on / off switches 104A to 104C has been described, the present invention is not limited to this. For example, a pulse-based modulation signal is generated for each antenna 108A to 108C. And a pulse generation operation of each pulse-based modulation signal generation unit may be controlled on and off according to transmission data. In short, among the plurality of antennas, the antenna that transmits the pulse-based modulation signal generated by the pulse-based modulation signal generation unit may be controlled according to the transmission data.

  In the present embodiment, a transmission apparatus having three transmission antennas has been described as an example. However, the present invention is not limited to this. As the number of transmitting antennas increases, the number of antenna combination patterns that simultaneously transmit modulated signals increases. Therefore, the number of bits that can be allocated to the pattern can be increased, and the data transmission speed can be increased accordingly. .

  In this embodiment, the case where the number of antennas of the transmission apparatus is 3 and the number of reception antennas is 1 has been described as an example. However, the present invention is not limited to this, and the data transmission speed increases as the number of transmission antennas increases. As the number of receiving antennas increases, the data reception quality improves.

  Furthermore, in this embodiment, the case where a pulse-based modulation signal is transmitted has been described as an example in which the effect of the present invention is particularly noticeable. However, the present embodiment is applicable to the case where a modulation signal other than a pulse-based modulation signal is transmitted. May be. For example, the present invention may be applied to a general communication system in which orthogonal modulation is performed using a carrier wave on the transmission side and orthogonal demodulation is performed on the reception side. Even in this case, similarly to the above-described embodiment, it is possible to obtain an effect of obtaining received data with good error rate characteristics by effectively utilizing the delayed wave that has caused the deterioration of the reception quality.

(Embodiment 3)
In Embodiment 1, the bit error rate at the time of reception is reduced by switching the antenna to be transmitted so that the relationship between the arrangement of the plurality of antennas and the bit of the transmission data is a gray coding relationship. A method was presented. In this Embodiment, the structure which can improve the receiving quality in a MIMO system is proposed by applying the same view to it to a MIMO (Multiple-Input Multiple-Output) system.

  FIG. 17 shows a configuration example of the base station in the present embodiment, and FIG. 18 shows a configuration example of the terminal in the present embodiment. Note that in this embodiment, a base station and a terminal will be described as an example. However, the configurations in FIGS. 17 and 18 are not limited to a base station and a terminal, and can be widely applied as configurations between communication stations that perform communication with each other. Is.

  In base station 1700 shown in FIG. 17, reception apparatus 1709 receives reception signal 1708 received by antenna 1707, demodulates it, obtains reception data 1710, and outputs this. The control unit 1711 receives the received data 1710, determines a frame configuration based on the received data 1710, and outputs a control signal 1712 indicating the frame configuration. Modulation signal generation sections 1702A to 1702D receive transmission data 1701A to 1701D and control signal 1712 as input, generate modulation signals 1703A to 1703D according to the frame configuration, and output them. The filters 1704A to 1704D receive the modulated signals 1703A to 1703D, respectively, form band-limited modulated signals 1705A to 1705D by performing band limitation, and send these to the antennas 1706A to 1706D.

  In terminal 1800 shown in FIG. 18, filters 1803X and 1803Y receive reception signals 1802X and 1803Y received by reception antennas 1801X and 1801Y, respectively filter them, and output reception signals 1804X and 1804Y after passing through the filter.

  Channel estimation units 1805X and 1805Y each receive received signals 1804X and 1804Y after passing through the filter, estimate the propagation environment (propagation fluctuation) using, for example, pilot symbols, and output the estimation result as propagation environment estimation signal 1806Y.

  The MMSE (Minimum Mean Square Error) calculation unit 1807 receives the received signals 1804X and 1804Y after passing through the filters and the propagation environment estimation signals 1806X and 1806Y, and separates the modulated signals multiplexed in space by executing the MMSE algorithm. Then, the separated modulated signals 1808A and 1808B are output.

  Demodulation sections 1809A and 1809B receive modulated data 1808A and 1808B, respectively, and perform demodulation processing to obtain received data 1810A and 1810B.

  The antenna selection unit 1811 receives the propagation environment estimation signals 1806X and 1806Y as input, selects an antenna from which the base station 1700 transmits a modulated signal based on these, and outputs an antenna selection information signal 1812 indicating the selected antenna.

  Transmitting apparatus 1814 receives antenna selection information signal 1812 and transmission data 1813 as input, forms modulated signal 1815 including antenna selection information, and outputs this as a radio wave from antenna 1816.

FIG. 19 shows the relationship between transmitting antennas 1706A to 1706D of base station 1700 and receiving antennas 1801X and 1801Y of terminal 1800. Propagation coefficients between the transmitting and receiving antennas are represented as h11, h12, h21, h22, h31, h32, h41, and h42. At this time, the signal transmitted from the antenna 1706A is Txa, the signal transmitted from the antenna 1706B is Txb, the signal transmitted from the antenna 1706C is Txc, the signal transmitted from the antenna 1706D is Txd, and the received signal received by the antenna 1801X is Rx1, If the received signal received by the antenna 1801Y is Rx2, the following relational expression is established.

  In this embodiment, reception quality is improved by selecting any two of the four transmission antennas 1706A to 1706D provided in the transmission apparatus (base station 1700) and transmitting the modulation signal of the data symbol. It is designed to improve. Further, in this embodiment, terminal 1800 designates an antenna that transmits a modulated signal of a data symbol in base station 1700.

  The main purpose of this embodiment is to specify the transmission antenna of the base station 1700 from the terminal 1800, and to reduce the reception quality at the terminal 1800 even if the antenna selection information specifying the transmission antenna is erroneously transmitted. It is to present a base station antenna number setting method that can be suppressed.

  FIG. 20 shows a frame configuration example of a modulated signal transmitted by base station 1700 and terminal 1800. In FIG. 20, the horizontal axis indicates time. Note that in the drawing, the antenna 1706A is abbreviated as the antenna A, the antenna 1706B as the antenna B, the antenna 1706C as the antenna C, and the antenna 1706D as the antenna D.

  At time 0, a synchronization symbol for terminal 1800 to acquire signal detection and time / frequency synchronization is transmitted from all antennas 1706A to 1706D of base station 1700.

  At time 1, a pilot symbol is transmitted from antenna 1706A. Channel estimation section 1805X of terminal 1800 can estimate h11 in equation (1) from this pilot symbol. Similarly, channel estimation section 1805Y of terminal 1800 can estimate h12 in equation (1) from this pilot symbol.

  At time 2, a pilot symbol is transmitted from antenna 1706B. Channel estimation section 1805X of terminal 1800 can estimate h21 in equation (1) from this pilot symbol. Similarly, channel estimation section 1805Y of terminal 1800 can estimate h22 in equation (1) from this pilot symbol.

  At time 3, a pilot symbol is transmitted from antenna 1706C. Channel estimation section 1805X of terminal 1800 can estimate h31 in equation (1) from this pilot symbol. Similarly, channel estimation section 1805Y of terminal 1800 can estimate h32 in equation (1) from this pilot symbol.

  At time 4, a pilot symbol is transmitted from antenna 1706D. Channel estimation section 1805X of terminal 1800 can estimate h41 in equation (1) from this pilot symbol. Similarly, channel estimation section 1805Y of terminal 1800 can estimate h42 in Expression (1) from this pilot symbol.

  In the antenna selection unit 1811 of the terminal 1800, for example, based on h11, h12, h21, h22, h31, h32, h41, and h42 in the equation (1), the base station 1700 selects two antennas that transmit the modulation signal. The selected antenna information is transmitted to the base station 1700.

Here, an example of an antenna selection method will be described. There are ₄ C ₂ = 6 ways to select two antennas from the four antennas. Therefore, consider the six matrices shown in the following equation.

  The antenna selection unit 1811 estimates the signal-to-noise power ratio when the multiplexed signals are separated based on the matrix. Then, the antenna selection unit 1811 selects the antenna combination (antenna pattern) that maximizes the signal-to-noise power ratio. For example, as shown in FIG. 20, it is assumed that antenna A and antenna C are selected. Then, the base station 1700 transmits data symbols from the antenna A and the antenna C (see times 7 and 8 in FIG. 20).

  By the way, “00” is assigned as an antenna identification number for designating antenna A, “01” is assigned as an antenna identification number for designating antenna B, and “10” is designated as an antenna identification number for designating antenna C. And "11" is assigned as an antenna identification number for designating the antenna D.

  When terminal 1800 selects antenna A and antenna C, information “00” and “10” is transmitted to base station 1700 as antenna selection information.

  However, depending on the transmission path, information “00” and “10” may be received by the base station 1700 by mistake. When the antenna identification number is received in error, the base station 1700 selects the wrong antenna and transmits the modulated signal. However, it is possible to minimize the deterioration of the reception quality at the terminal 1800 as much as possible. desired.

  In consideration of this point, in the present embodiment, antenna allocation (antenna as shown in FIG. 9 or FIG. 10) is used as a bit allocation method for transmission antennas (that is, an identification number allocation method for transmission antennas). Apply gray coding based on (distance). In other words, the antenna identification numbers of the plurality of transmission antennas are determined so that the relationship between the arrangement of the plurality of antennas and the antenna identification numbers of the plurality of transmission antennas is a gray coding relationship.

  Specifically, bit (identification number) allocation is performed such that the difference between bits increases as the transmission antenna has a longer distance between antennas. In other words, bit (identification number) allocation is performed so that the difference between the bits decreases as the transmission antenna has a shorter distance between antennas.

  Here, when some bits of the bit string indicating the antenna identification number as the antenna selection information are erroneously received on the transmission side, the transmission side selects the wrong transmission antenna and performs transmission. By applying gray coding based on the antenna arrangement (inter-antenna distance) as described above, the transmission antenna that is erroneously selected on the transmission side becomes an antenna adjacent to the transmission antenna that should be originally selected. Thereby, it is possible to suppress a decrease in reception quality when the antenna selection information is transmitted in error.

  Hereinafter, this point will be described in detail.

  It is more likely that a 1-bit error will occur than a 2-bit error. When a bit (identification number) is assigned to each antenna as shown in FIGS. 9 and 10, when a 1-bit error occurs, the antenna next to the antenna that should be originally selected is selected. At this time, since the antenna adjacent to the antenna that should have been selected has a large correlation with the antenna that should have been selected, the possibility that a large difference in channel estimation values will occur is low. Therefore, there is a high possibility that reception quality is ensured. Therefore, by performing gray coding based on the antenna arrangement (inter-antenna distance) as shown in FIG. 9 and FIG. 10 for antenna identification, the reception quality is lowered when the antenna selection information is transmitted in error. Can be suppressed.

  Note that the arrangement of FIG. 10 is more suitable for ensuring reception quality than FIG. The reason will be described. In the case of FIG. 9, when “00” is the antenna to be selected (antenna AN_A), if the base station 1700 erroneously determines that “10” is selected, the base station 1700 selects the antenna AN_C. . At this time, since the antenna AN_A and the antenna AN_C have very low antenna correlation, there is a high possibility that reception quality will be greatly affected (reception quality may be deteriorated) due to incorrect antenna selection. On the other hand, in the case of FIG. 10, since there is no such a unique relationship, even if a 1-bit error occurs, a highly correlated antenna may be selected and reception quality may be ensured. high.

  As described above, according to the present embodiment, Gray coding based on antenna arrangement (inter-antenna distance) is applied to a method of assigning bits to transmission antennas (that is, a method of assigning identification numbers to transmission antennas). Accordingly, even when a transmission error occurs in the antenna selection information, it is possible to suppress a decrease in reception quality.

  That is, in a transmission control method in a radio communication system having a first radio station having a plurality of transmission antennas and a second radio station communicating with the first radio station, the arrangement of the plurality of antennas; The antenna identification numbers of the plurality of transmission antennas are determined such that the relationship between the antenna identification numbers of the plurality of transmission antennas is a Gray coding relationship, and the second radio station determines the antenna identification number. If a transmission control signal for controlling the transmission of the plurality of transmission antennas is transmitted to the first wireless station using the radio signal, even if a transmission error occurs in the antenna selection information, the reception quality decreases. Can be suppressed.

  In the present embodiment, the case where the number of antennas of the base station is 4 and the number of antennas of the terminal is 2 has been described as an example. The same effect can be obtained in any case. In addition, although the antenna selection has been described in the present embodiment, the present invention is not limited to this, and there is an effect that deterioration of reception quality can be suppressed even when the antenna identification information and the control information are transmitted as a set. can get.

For example, as shown in FIG. 21, the transmitting side and the receiving side have four antennas, the transmitting side transmits four modulated signals using the four antennas, and the receiving side receives the original from the multiplexed signal received by the four antennas. Consider a 4 × 4 spatial multiplexing MIMO system that separates the modulated signals. At this time, the following relational expression is established.

  In such a MIMO system, even when the terminal side instructs the base station to “increase the transmission power of antenna A” or “switch the modulation method of the modulation signal transmitted from antenna B”, If the above-described Gray coding is applied to the antenna designation, the same effect as described above can be obtained.

  In this embodiment, a simple example is shown. However, the present invention is not limited to the above-described embodiment. For example, orthogonal modulation is performed using a carrier wave on the transmission side, and orthogonal demodulation is performed on the reception side. When performing, in the case of UWB, the case of using a multicarrier communication system such as OFDM or the case of using a spread spectrum communication system can be similarly implemented.

(Embodiment 4)
In the third embodiment, a case has been described in which an antenna identification method based on gray coding based on antenna arrangement (inter-antenna distance) is applied to a spatial multiplexing MIMO system. In the present embodiment, a detailed description will be given of a case where the antenna identification method based on gray coding based on the antenna arrangement (inter-antenna distance) is applied to eigenmode communication in a MIMO system.

  First, the eigenmode communication in the MIMO system will be briefly described.

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

  In particular, as a communication mode in which a plurality of channels are configured in a communication space and a signal is multiplexed and transmitted, there is an eigenmode (eigenmode) using a singular vector or an eigen vector of a channel matrix. This eigenmode is a method of using these singular vectors and eigenvectors as the channel signature vector described above. Here, the channel matrix is a matrix whose elements are complex channel coefficients of a combination of all or a part of each antenna element of the transmitting array antenna and each antenna element of the receiving array antenna.

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

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

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

  FIG. 22 shows a configuration of base station 2200 and terminal 2220 as a configuration example of the eigenmode communication system.

  The channel analysis unit 2207 of the base station 2200 calculates a plurality of transmission channel signature vectors to form a multiplexed channel based on channel state information that is an estimation result of a propagation channel between the base station 2200 and the terminal 2220. In addition, the channel matrix formed by the channel state information is based on SVD (SVD: Singular Value Decomposition), eigenvalues (for example, λA, λB, λC,..., ΛX), and eigenpaths (for example, path A, Path B, path C,..., Path X) are obtained and output as control information 2208.

  Multiplex frame generation section 2201 of base station 2200 receives a transmission digital signal and control information 2208 as input, generates a plurality of transmission frames for mapping to a multiplexed channel, and transmits a transmission digital signal 2202A for channel A and a transmission for channel B. Digital signal 2202B,..., Channel X transmission digital signal 2202X is output.

  Encoding / modulating sections 2203A to 2203X receive transmission digital signals 2202A to 2202X of channel A to channel X and control information 2208, respectively, determine the coding rate and modulation method based on control information 2208, and determine the determined code The transmission digital signals 2202A to 2202X are encoded and modulated by the conversion rate / modulation method to obtain the baseband modulation signals 2204A to 2204X of the channels A to X and output them.

  The vector multiplexing unit 2205 receives the baseband modulation signals 2204A to 2204X of channel A to channel X and the control information 2208, and multiplies each baseband modulation signal 2204A to 2204X by a channel signature vector and combines them. The signal is supplied to the transmission array antenna 2206. In this way, the base station 2200 transmits a signal vectorized using the channel signature vector from the transmission array antenna 2206 to the terminal 2220.

  The terminal 2220 receives a plurality of reception channels in order to separate multiplexed transmission signals based on channel state information that is an estimation result of a propagation channel between the base station 2200 and the terminal 2220 by the reception channel analysis unit 2215. A signature vector is calculated. Multiplex separation section 2210 receives the reception signals received by reception array antenna 2209 and multiplies each channel signature vector to obtain a plurality of reception signals, that is, reception signals 2211A to 2211X of channel A to channel X. obtain.

  Decoding sections 2212A to 2212X receive reception signals 2211A to 2211X of channel A to channel X and transmission method information 2218, respectively, and perform decoding based on transmission method information 2218 (modulation scheme and coding rate information). , Channel A to channel X digital signals 2213A to 2213X are obtained and output.

  The transmission method information detection unit 2217 receives the digital signal 2213A of channel A, extracts the transmission method of the modulation signal of each channel, for example, information such as modulation scheme and coding rate, and decodes these as transmission method information 2218. The data is sent to the units 2212A to 2212X.

  Received data combining section 2214 receives channel A to channel X digital signals 2213A to 2213X and transmission method information 2218 as input, and obtains received digital signals.

  Here, as described above, in the transceiver (base station 2200 and terminal 2220), the terminal 2220 notifies the base station 2200 of channel state information (CSI: Channel State Information) for the modulated signal transmitted by the base station 2200. think about.

  In this case, a plurality of channel information corresponding to each transmission antenna of the base station 2200 and each reception antenna of the terminal 2220 exists. Accordingly, the terminal 2220 needs to transmit a plurality of channel information to the base station 2200.

  In the present embodiment, a suitable transmission method of this channel information is presented.

  For example, as shown in FIG. 21, the transmitting device of the base station has four transmitting antennas 1901A, 1901B, 1901C and 1901D, and the receiving device of the terminal has four receiving antennas 1902P, 1902Q, 1902R and 1902S. Think about the case. In this case, there are 16 types of channel state information: h11, h12, h13, h14, h21, h22, h23, h24, h31, h32, h33, h34, h41, h42, h43, h44. It is necessary to correctly transmit this information to the base station. However, there is a possibility of error when transmitting wirelessly.

  In the present embodiment, when channel state information is erroneously transmitted, in order to reduce the influence as much as possible, an antenna by Gray coding based on the same antenna arrangement (inter-antenna distance) as in the third embodiment Use specific methods.

  FIG. 23 shows a configuration example of information that the terminal feeds back to the base station. Since there are 16 types of channel state information, the feedback information is composed of a base station transmitting antenna number, a terminal receiving antenna number, and channel state information, as shown in the figure. Here, there is a possibility that the information is erroneous due to transmission. However, if Gray coding based on antenna arrangement (distance between antennas) as described in Embodiment 3 is applied to the transmission antenna number of the base station and / or the reception antenna number of the terminal, the antenna correlation becomes closer to the closer antennas. Since it is high, the influence on the reception quality is reduced even if the antenna number is erroneously transmitted.

  As described above, antenna identification information in eigenmode communication is obtained by applying the antenna identification method based on the antenna arrangement (distance between antennas) described in Embodiment 3 to eigenmode communication in the MIMO system. Even if the message is transmitted by mistake, it is possible to suppress the deterioration of the reception quality.

  In the present embodiment, the case where the number of antennas of the base station is 4 and the number of antennas of the terminal is 2 has been described as an example. The same effect can be obtained in any case.

  In this embodiment, a simple example is shown. However, the present invention is not limited to the above-described embodiment. For example, orthogonal modulation is performed using a carrier wave on the transmission side, and orthogonal demodulation is performed on the reception side. When performing, in the case of UWB, the case of using a multicarrier communication system such as OFDM or the case of using a spread spectrum communication system can be similarly implemented.

(Embodiment 5)
In the first embodiment, in the multi-antenna system, by using the correlation calculation, the delayed wave is effectively used to reduce the influence of the multipath, so that even in a broadband modulation signal such as a pulse-based modulation signal, This paper describes a method that enables multi-antenna communication to increase data transmission speed.

  In the present embodiment, a method that enables MIMO communication using spatial multiplexing even for a wideband modulation signal such as a pulse-based modulation signal by an operation equivalent to a correlation operation is presented.

  FIG. 24 shows the configuration of base station 2400 and terminal 2420 as a configuration example of the MIMO communication system of the present embodiment.

  Base station 2400 inputs transmission data 2401A and 2401B to pulse-based modulation signal generation sections 2402A and 2402B, respectively. Pulse-based modulation signal generation sections 2402A and 2402B generate pulse-based modulation signals 2403A and 2403B based on transmission data 2401A and 2401B, respectively, and send them to filters 2404A and 2404B. Each of the filters 2404A and 2404B receives the pulse-based modulation signals 2403A and 2403B, performs band limitation, and transmits the band-limited pulse-based modulation signals 2405A and 2405B to the antennas 2406A and 2406B.

  Terminal 2420 inputs received signals 2408X and 2408Y received by receiving antennas 2407X and 2407Y to filters 2409X and 2409Y, respectively. The filters 2409X and 2409Y send the received signals 2410X and 2410Y after filtering to the integrators 2411X and 2411Y, respectively.

  The integrators 2411X and 2411Y receive the filtered received signals 2410X and 2410Y, respectively, and integrate them for a certain period. This integration interval will be described in detail later. Integrators 2411X and 2411Y send integrated received signals 2412X and 2412Y to channel estimation units 2413X and 2413Y and MMSE processing unit 2415, respectively.

  The channel estimation units 2413X and 2413Y receive the integrated received signals 2412X and 2412Y, respectively, detect symbols that can be used for channel estimation such as pilot symbols and preambles included in the received signals 2412X and 2412Y, and based on the symbols. Channel fluctuation is estimated, and channel fluctuation estimation signals 2414X and 2414Y are output.

  The MMSE processing unit 2415 receives the integrated reception signals 2412X and 2412Y and the channel fluctuation estimation signals 2414X and 2414Y as inputs, and executes the MMSE algorithm to separate the combined signal in space, thereby modulating the signal 2416A. , 2416B is obtained.

  The demodulating units 2417A and 2417B receive the modulated signals 2416A and 2416B, respectively, and demodulate them to obtain received data 2418A and 2418B.

FIG. 25 shows the relationship between transmission antennas 2406A and 2406B of base station 2400 and reception antennas 2407X and 2407Y of terminal 2420. Propagation coefficients between the transmitting and receiving antennas are represented as h11, h12, h21, and h22. At this time, if the signal transmitted from the antenna 2406A is Txa, the signal transmitted from the antenna 2406B is Txb, the received signal received by the antenna 2407X is Rx1, and the received signal received by the antenna 2407Y is Rx2, the following relational expression is established. To do.

  The propagation coefficients h11 and h21 are estimated by the channel estimation unit 2413X in FIG. 24, and the propagation coefficients h12 and h22 are estimated by the channel estimation unit 2413Y. Further, the MMSE processing unit 2415 estimates the modulation signal Txa and the modulation signal Txb using the relational expression of Expression (9).

  FIG. 26 shows a frame configuration example of a modulated signal transmitted by the base station 2400. In FIG. 26, the horizontal axis indicates time. In the figure, antenna 2406A is abbreviated as antenna A and antenna 2406B is abbreviated as antenna B.

  At time 0, the antennas 2406A and 2406B transmit a synchronization symbol for the terminal 2420 to acquire signal detection and time / frequency synchronization. At time 1, a pilot symbol is transmitted from antenna 2406A. Channel estimation section 2413X of terminal 2420 can estimate h11 in equation (1) from this pilot symbol. Similarly, channel estimation section 2413Y of terminal 2420 can estimate h12 in equation (1) from this pilot symbol. At time 2, pilot symbols are transmitted from antenna 2406B. Channel estimation section 2413X of terminal 2420 can estimate h21 in equation (1) from this pilot symbol. Similarly, channel estimation section 2413Y of terminal 2420 can estimate h22 in Equation (1) from this pilot symbol.

  From time 3 to time 8, data symbols are transmitted simultaneously from antennas 2406A, 2406B.

  By the way, generally, as a method for reducing the influence of multipath fading due to a delayed wave, a method using an OFDM (Orthogonal Frequency Division Multiplexing) signal as a modulation signal, or a rake reception on the receiving side using a spread spectrum signal as a modulation signal The method of doing is known. In a wireless local area network (LAN) or the like, a MIMO system that reduces the influence of delayed waves by using these modulated signals in a MIMO system has been studied.

  However, for example, when a wideband signal such as UWB using a pulse-based modulation signal is to be subjected to spatial multiplexing MIMO transmission, a very high-speed signal processing device is required to handle the wideband frequency. Even if the influence of the delayed wave is reduced in combination with the spread spectrum communication method, there is a disadvantage that the power consumption and circuit scale of the device increase. For these reasons, it is not practical to transmit a wideband signal such as UWB using a pulse-based modulation signal in a spatial multiplexing MIMO system.

  The inventors of the present invention can effectively use the delayed wave by using the correlation calculation in the same manner as in the first embodiment, integrate the correlation result for a certain period of time, and use the integration result. It was considered that even a broadband modulation signal such as a modulation signal can be easily applied to a spatial multiplexing MIMO system.

  In a wireless communication system using a narrow band frequency, the influence of multipath is small because the symbol time is long. This is because a symbol time sufficient to reduce the influence of intersymbol interference can be secured.

  On the other hand, in a wireless communication system using a wideband frequency, since the symbol time is short, the influence of multipath is large. The method presented in this embodiment can effectively reduce the influence of multipath even with a short symbol time.

  FIG. 27 shows an example of the waveform of the received signal (FIGS. 27A and 27B) and the waveform (FIG. 27C) when the received signal is integrated over a certain period. FIG. 27A shows the waveform of the received signal on the time axis when there is no delayed wave. FIG. 27B shows an example of a waveform on the time axis of the received signal when a delayed wave exists. FIG. 27 (c) shows an example of a waveform when the received signal (FIG. 27 (b)) when a delayed wave exists is integrated in one symbol section.

  When a delay wave exists, a signal due to the delay wave exists. FIG. 27B is a diagram showing a received signal when there are two delayed waves. When integration is performed as shown in FIG. 27C (in FIG. 27C, integration is performed from Δ to Δ in the figure), the value obtained at the end of the integration interval is a virtual length of the symbol interval. In other words, the situation is the same as when the frequency band is narrowed. Thereby, the influence of a delay wave can be reduced.

  What is important here is what value the integration interval is set to. The accuracy of setting the integration interval is important for improving both the data transmission rate and the reception quality.

  Therefore, a preferred example of how to set the integration interval will be described next.

  FIG. 28 shows a frame configuration example of the modulation signal in this embodiment. At time 0, the base station 2400 transmits a synchronization symbol for the terminal 2420 to acquire signal detection and time / frequency synchronization from the antennas 2406A and 2406B.

  At time 1, a delayed wave estimation training symbol that is a modulation signal (pulse) for terminal 2420 to estimate the state of the delayed wave is transmitted from antenna 2406A. On the other hand, no modulated signal (pulse) is transmitted from antenna 2406B. Thereby, terminal 2420 can estimate the state of the delayed wave from received signals 2410X and 2410Y after passing through the filter. In FIG. 24, the portion for estimating the state of the delayed wave is not shown, but for example, a delayed wave state estimation unit may be arranged at the subsequent stage of the filters 2409X and 2409Y.

  A symbol interval (time 2) immediately after the training symbol for delay wave estimation at time 1 is a guard interval (interval in which a modulation signal is not transmitted) for both of the two antennas 2406A and 2406B. This guard interval is very important for delay wave estimation of the present embodiment. The reason will be described in detail later.

  At time 3, a delayed wave estimation training symbol which is a modulated signal (pulse) for terminal 2420 to estimate the status of the delayed wave is transmitted from antenna 2406B. On the other hand, no modulated signal (pulse) is transmitted from antenna 2406A. Thereby, terminal 2420 can estimate the state of the delayed wave from received signals 2410X and 2410Y after passing through the filter.

  The symbol interval (time 4) immediately after the training symbol for delay wave estimation at time 3 is a guard interval (interval where no modulation signal is transmitted) for both of the two antennas 2406A and 2406B. This guard interval is very important for delay wave estimation of the present embodiment. The reason will be described in detail later.

  The terminal 2420 receives the training symbol for delay wave estimation described above, estimates the delay wave situation, and determines an integration interval.

  In the present embodiment, the base station 2400 is notified of the status of the delayed wave. At time 5 and time 6, terminal 2420 transmits a control information symbol for notifying base station 2400 of a delay wave condition and the like.

  At time 7, base station 2400 transmits a control information symbol including transmission method change information when the transmission method is changed in response to a notification of the delay wave situation from terminal 2420.

  At time 8, base station 2400 transmits a pilot. This pilot symbol is a symbol for terminal 2420 to estimate channel fluctuations in order to realize spatial multiplexing MIMO communication. At time 9, base station 2400 transmits a data symbol.

  Next, an example will be described in which the pulse-based modulation signal generation unit 2402 of the base station 2400 switches the communication method (in this embodiment, one symbol interval length) based on the delayed wave status notified from the terminal 2420. .

  FIG. 29 shows an example of waveforms of two types of pulse-based modulation signals having different one symbol intervals. In an environment where the delay dispersion is large, in order to reduce the influence of the delayed wave, as shown in FIG. 29B, in order to accurately grasp the delayed wave, it is better to set one symbol interval longer. good. However, if one symbol period is lengthened, the data transmission rate decreases. On the other hand, in an environment where the delay dispersion is small, the influence of the delay wave is small. Therefore, as shown in FIG. 29A, the delay wave can be accurately grasped. Good. Also, if one symbol period is shortened, the data transmission rate is improved.

  In the present embodiment, base station 2400 is configured to transmit a modulated signal having a longer symbol length as the delay dispersion is larger. Thereby, it is possible to achieve both improvement in data transmission speed and improvement in reception quality.

  By the way, in FIG. 28, the pilot symbol and the data symbol have one symbol period changed according to the situation of the delayed wave, but the other symbols need to be transmitted to the communication partner as accurately as possible. It is better to lengthen one symbol section as in 29 (b). In particular, the delayed wave estimation training symbol is a basis for setting one symbol interval, and in the present embodiment, a guard interval is provided immediately after the delayed wave estimation training symbol. As a result, even if the delayed wave reaches the guard interval, the delayed wave can be estimated with high accuracy, so that one symbol interval can be set accurately, further improving the data transmission rate and receiving. It becomes possible to achieve both improvement in quality.

  As described above, according to the present embodiment, by providing integrators 2411X and 2411Y that integrate the received signal for a certain period in each antenna branch of the receiving device, a wideband signal such as a pulse-based modulation signal is provided. However, MIMO communication can be made possible. Furthermore, diversity gain can be obtained. In addition, since the integration interval is set according to the delay dispersion of the received signal, it is possible to achieve both improvement in data transmission speed and improvement in reception quality.

  In addition, according to the present embodiment, by integrating a certain section of a channel fluctuation estimation symbol, even a wideband signal (a signal having a very short one symbol section) such as a pulse-based modulation signal has high accuracy. It is possible to realize a channel fluctuation estimation method that can estimate channel fluctuations of

  In the present embodiment, a case has been described in which one symbol period of the base station is changed in accordance with the delay state in addition to the integration period of integrators 2411X and 2411Y, but only the integration period of integrators 2411X and 2411Y is described. May be changed.

  In this embodiment, the case where there are two transmission antennas and two reception antennas has been described as an example. However, the present invention is not limited to this.

  The present invention has an effect that multi-antenna transmission is possible even for a wideband signal such as a pulse-based modulation signal, and the transmission speed of the wideband signal can be improved, and wireless transmission is performed using a plurality of transmission antennas. Widely applicable to communication systems.

The block diagram which shows the structural example of the transmitter which concerns on Embodiment 1 of this invention. FIG. 11 is a diagram illustrating a frame configuration example of a modulation signal transmitted by the transmission apparatus according to the first embodiment. It is a figure with which it uses for description of the transmission signal of the antenna A in the time 1 to the time 4, (a) is a figure which shows a frame structure, (b) is a figure which shows a transmission waveform. FIG. 3 is a diagram for explaining a data symbol transmission operation in the first embodiment, where (a) is a diagram illustrating a relationship between bit allocation and pulse on / off control, and (b) is a diagram illustrating a transmission waveform. FIG. 3 is a block diagram illustrating an example of the overall configuration of the receiving apparatus according to the first embodiment. Block diagram showing a configuration example of a demodulator The figure which serves for explanation of the signal waveform which is remembered in the waveform memory section 4A and 4B are diagrams for explaining a demodulation operation according to the first embodiment, where FIG. 5A is a diagram illustrating a signal waveform stored in a waveform storage unit, and FIG. 5B is a diagram illustrating a received data determination operation; The figure which shows the relationship between the installation position of a transmission antenna and allocation of the transmission bit to each transmission antenna in embodiment The figure which shows the relationship between the installation position of a transmission antenna and allocation of the transmission bit to each transmission antenna in embodiment FIG. 7 is a block diagram illustrating another configuration example of the receiving apparatus according to the first embodiment. Block diagram showing the configuration of the composition determination unit FIG. 9 is a block diagram illustrating a configuration example of a transmission apparatus according to the second embodiment. FIG. 10 is a diagram illustrating a frame configuration example of a modulation signal transmitted by the transmission apparatus according to the second embodiment. FIG. 10 is a diagram for explaining a data symbol transmission operation in the second embodiment, where (a) is a diagram illustrating a relationship between bit allocation and pulse on / off control, and (b) is a diagram illustrating a transmission waveform. FIG. 9 is a block diagram showing a configuration of a demodulation unit in the receiving apparatus of the second embodiment FIG. 9 is a block diagram illustrating a configuration example of a base station according to the third embodiment. FIG. 9 is a block diagram illustrating a configuration example of a terminal according to the third embodiment. The figure which shows the relationship between transmission / reception in Embodiment 3. The figure for explanation of communication operation in the third embodiment The figure which shows the relationship between transmission and reception when four antennas are provided on both the transmission side and the reception side FIG. 9 is a block diagram illustrating a configuration example of a base station and a terminal performing eigenmode communication in the fourth embodiment The figure which shows the structural example of the information which a terminal feeds back to a base station FIG. 9 is a block diagram illustrating a configuration example of a base station and a terminal in the fifth embodiment The figure which shows the relationship between transmission / reception in Embodiment 5. The figure which shows the frame structural example of the modulation signal which a base station transmits FIG. 10 is a diagram for explaining an integration operation in the fifth embodiment, where (a) shows a received waveform when there is no delayed wave, (b) shows a received waveform when there is a delayed wave, (C) is a figure which shows a waveform when the received signal when a delay wave exists is integrated in 1 symbol area. FIG. 10 is a diagram for explaining communication operations in the fifth embodiment. FIG. 7 is a diagram for explaining a transmission operation of a base station in Embodiment 5, where (a) shows a state in which one symbol section is set short, and (b) shows a state in which one symbol section is set long. Block diagram showing a conventional configuration example of a system for transmitting a pulse-based modulation signal using a plurality of antennas

Explanation of symbols

100, 1300 Transmission device 101 Transmission data 102, 2402A, 2402B Pulse-based modulation signal generation unit 103, 2403A, 2403B Pulse-based modulation signal 104A-104D On-off switch 109, 1301 Control unit 500, 1100 Reception device 505, 505X, 505Y, 1600 Demodulation unit 604A to 604D, 604AB, 604AC, 604BC, 604ABC Waveform storage unit 606A to 606D, 606AB, 606AC, 606BC, 606ABC Correlation calculation unit 608, 1203 determination unit 1103 synthesis determination unit 1700, 2200, 2400, base station 1800 2420 terminal 1805X, 1805Y, 2413X, 2413Y channel estimation unit 1807, 2415 MMSE processing unit 2411X, 2411Y Minute unit

Claims (8)

Multiple antennas,
UWB signal generation means for generating a UWB signal based on transmission data;
A multi-antenna transmission apparatus comprising: a transmission antenna control unit configured to switch and control an antenna that transmits a UWB signal generated by the UWB signal generation unit among the plurality of antennas according to the transmission data. The UWB signal generation means is pulse-based modulation signal generation means for generating a pulse-based modulation signal based on transmission data,
The multi-antenna transmission apparatus according to claim 1, wherein the transmission antenna control unit controls an antenna that transmits a pulse-based modulation signal generated by the pulse-based modulation signal generation unit according to the transmission data. 2. The multi-antenna transmission according to claim 1, wherein the transmission antenna control unit performs switching control of the antenna to be transmitted so that a relationship between an arrangement of the plurality of antennas and a bit of the transmission data is a gray coding relationship. apparatus. The multi-antenna transmission apparatus according to claim 1, wherein the transmission antenna control means switches and controls combinations of antennas that transmit simultaneously according to the transmission data. A UWB signal generation step for generating a UWB signal based on the transmission data;
A multi-antenna transmission method comprising: a transmission antenna control step of switching and controlling an antenna that transmits a UWB signal generated in the UWB signal generation step among a plurality of transmission antennas according to the transmission data. Waveform storage means for individually storing a plurality of reception waveforms of signals transmitted from a plurality of transmission antennas provided in a partner station for each transmission antenna;
Correlation calculating means for obtaining a plurality of correlation values by obtaining a correlation between the plurality of received waveforms stored in advance in the waveform storage means and the currently received received waveform;
A receiving device comprising: a determining unit that determines that a signal is transmitted from a transmitting antenna corresponding to a received wave system in which the largest correlation value is obtained by the correlation calculating unit among the plurality of received waveforms. The plurality of transmission antennas are associated with transmission bits;
The receiving device according to claim 6, wherein the determination unit uses, as received data, a bit corresponding to a transmission antenna that is determined to have transmitted a signal. Among the plurality of transmission antennas, a combination of two or more transmission antennas transmitted simultaneously is associated with a transmission bit,
The waveform storage means stores, for each combination of two or more transmission antennas transmitted simultaneously, a reception waveform of a signal transmitted simultaneously from the combined transmission antenna,
The correlation calculating means obtains the correlation values by calculating the correlation between the received waveform and the currently received received waveform for each combination of the transmission antennas that are stored in advance in the waveform storing means. Get
The determination unit determines that a signal is transmitted by a combination of transmission antennas corresponding to the reception wave system in which the largest correlation value is obtained by the correlation calculation unit from among a plurality of reception waveforms, and the combination of the transmission antennas The receiving device according to claim 6, wherein the bit corresponding to is received data.

Images