JP2014220823A - Radio communication system and radio communication method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve a MIMO reception characteristic.SOLUTION: A base station includes: a MIMO pre-coding unit 32 for converting transmission data addressed to a mobile station to two data streams corresponding to two reception antennas included by the mobile station respectively, by performing MIMO pre-coding on the transmission data; a weight calculation unit for calculating a transmission weight for forming a directivity pattern directed to each of the two reception antennas; and a weighting/combining unit 34 for generating two combined data streams supplied to antennas 20-1, 20-2 respectively, by weighting each of the two data streams with a transmission weight calculated for a reception antenna of the mobile station corresponding to the data stream and combining the weighted two data streams for each antenna 20. The two combined data streams are transmitted from the antennas 20-1, 20-2 respectively.

Description

  The present invention relates to a radio communication system and a radio communication method, and more particularly to improvement of a multiple-input multiple-output (MIMO) system.

  In recent years, various MIMO systems have begun to be adopted in wireless communication systems. For example, WiMAX (Worldwide Interoperability for Microwave Access) employs STBC (Space-Time Block Coding), which is resistant to propagation path fluctuations, and SM (Spatial Multiplexing), which has high throughput. (For example, refer nonpatent literature 1).

Takashi Shono, “WiMAX Textbook”, Impress R & D, Inc., July 2008, p145, 154

  In a wireless communication system employing the MIMO scheme, further improvement in reception characteristics is desired.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a radio communication system and a radio communication method capable of improving MIMO reception characteristics.

  In order to solve the above problems, a transmitting apparatus according to the present invention forms a directivity pattern directed to a receiving antenna for each of a plurality of transmitting antennas and a plurality of receiving antennas of the receiving apparatus. Weight calculating means for calculating transmission weights for receiving, and receiving means for receiving a plurality of known reference symbols having low correlation with each other transmitted at the same frequency and at the same timing by the plurality of receiving antennas. And the weight calculation means directs a main beam to the reception antenna for each of the plurality of reception antennas and nulls to reception antennas other than the reception antenna based on reference symbols received by the plurality of transmission antennas. Calculate the transmission weight to form the directivity pattern Characterized in that it.

  In the present invention, the transmission device weights a data stream corresponding to the reception antenna with the calculated transmission weight, and synthesizes the weighted data stream for each transmission antenna, thereby transmitting the plurality of transmission antennas. Are provided with transmitting means for transmitting each of.

  In addition, the wireless communication method according to the present invention includes a plurality of transmission antennas and a transmission weight for forming a directivity pattern directed to the reception antenna by each of the plurality of transmission antennas. And a means for receiving a plurality of known reference symbols having low correlation with each other transmitted at the same frequency and at the same timing by the plurality of receiving antennas. In the wireless communication method, for each of the plurality of reception antennas, directing a main beam to the reception antenna and directing a null to reception antennas other than the reception antenna based on reference symbols received by the plurality of transmission antennas Span for calculating the transmission weight for forming the directivity pattern Characterized in that it has Tsu and up, the.

It is a figure which shows the structure of the radio | wireless communications system which concerns on embodiment of this invention. It is a figure which shows the radio channel structure in the radio | wireless communications system which concerns on this embodiment. It is a figure which shows the propagation path of the data stream by the conventional MIMO system. It is a figure which shows the propagation path of the data stream which concerns on this embodiment. It is a figure which shows the receiving characteristic of the conventional MIMO system, and the receiving characteristic of this embodiment. It is a functional block diagram of the base station which concerns on this embodiment. It is a functional block diagram of the mobile station which concerns on this embodiment. It is a figure which shows the structure which concerns on the MIMO precoding and weighting synthesis | combination of a STBC system. It is a figure which shows the structure which concerns on the MIMO system precoding and weighting synthesis of SM system. It is a figure which shows an example of the detailed structure of PRU which concerns on this embodiment. It is a sequence diagram which shows an example of the radio | wireless communication method which concerns on this embodiment.

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

  FIG. 1 is a diagram showing a configuration of a wireless communication system 10 according to an embodiment of the present invention. As shown in FIG. 1, the wireless communication system 10 includes a base station 12 and a plurality of mobile stations 14 (only mobile stations 14-1 to 14-3 are shown here).

  The base station 12 performs a plurality of movements using an OFDMA (Orthogonal Frequency Division Multiple Access) method and a TDMA / TDD (Time Division Multiple Access / Time Division Duplex) method. Multiplex communication with the station 14 is performed.

  FIG. 2 is a diagram showing a radio channel configuration in the radio communication system 10. As shown in the figure, in the radio communication system 10, a TDMA frame having a predetermined time width (here, 5 ms) is divided into an upstream subframe (2.5 ms) and a downstream subframe (2.5 ms). Each frame is equally divided into a plurality of time slots (here, Slot 1 to Slot 4). A plurality of OFDMA subchannels (here, Sch1 to Sch18) are defined in a predetermined frequency band. The minimum unit of the radio channel that the base station 12 allocates to the mobile station 14 is called a PRU (Physical Resource Unit), and each PRU is either one of time slots (Slot 1 to Slot 4) and one of subchannels (Sch 1 to Sch 18). , Belongs to.

  In addition, the base station 12 and the mobile station 14 have a plurality of antennas, and can perform high-speed communication by a MIMO scheme (STBC-MIMO scheme, SM-MIMO scheme, etc.) that performs MIMO precoding on transmission data. it can.

  In the conventional MIMO scheme, a base station (MIMO transmission apparatus) converts transmission data addressed to a mobile station (MIMO reception apparatus) into a plurality of data streams by MIMO precoding, and then converts the plurality of data streams into a plurality of transmission antennas. (See FIG. 3A). Then, the mobile station receives a multiplexed signal in which a plurality of data streams respectively transmitted from the transmitting antennas of the base station are overlapped by a plurality of receiving antennas, and performs MIMO decoding on the received multiplexed signal, thereby transmitting transmission data. get.

  On the other hand, in the radio communication system 10, the base station 12 (transmitting apparatus) converts transmission data addressed to the mobile station 14 (MIMO receiving apparatus) into a plurality of data streams by MIMO precoding, and then the plurality of data streams. Are transmitted in a space division multiplexing manner with a directivity pattern directed to the receiving antenna of the mobile station 14 corresponding to the data stream (see FIG. 3B). Then, the mobile station 14 receives each of a plurality of data streams transmitted from the base station 12 by a receiving antenna corresponding to the data stream, and acquires transmission data by performing MIMO decoding on the received data stream. To do.

  For this reason, in the radio communication system 10, when the fluctuation of the radio propagation path interposed between the base station 12 and the mobile station 14 is small, the beamforming gain due to the spatial division multiplexing directivity pattern formed by the base station 12 is small. Easy to obtain. This beamforming gain exceeds the MIMO reception combining gain obtained by the conventional MIMO system in which transmission is omnidirectional. Also, interference suppression can be achieved by null steering. On the other hand, when the fluctuation of the radio propagation path is large, it is difficult to obtain a beamforming gain due to disturbance of the directivity pattern of space division multiplexing, but instead, a MIMO reception combined gain equivalent to that of the conventional MIMO system can be obtained. . That is, according to the radio communication system 10, as shown in FIG. 4, especially when the fluctuation of the radio propagation path interposed between the base station 12 and the mobile station 14 is small, the MIMO reception characteristics in the mobile station 14 are improved. be able to.

  Below, the structure with which the base station 12 and the mobile station 14 are provided in order to implement | achieve the said process is demonstrated concretely.

  FIG. 5 is a functional block diagram of the base station 12. As shown in FIG. 5, the base station 12 includes a plurality of antennas 20 (here, antennas 20-1 and 20-2), a radio communication unit 22, a primary demodulation unit 24, a weight calculation unit 26, and a secondary demodulation unit 28. A secondary modulation unit 30, a MIMO precoding unit 32, a weighting synthesis unit 34, and a primary modulation unit 36 are included.

  FIG. 6 is a functional block diagram of the mobile station 14. As shown in FIG. 6, the mobile station 14 includes a plurality of antennas 40 (here, antennas 40-1 and 40-2), a radio communication unit 42, a primary demodulation unit 44, a channel calculation unit 46, a MIMO decoding unit 48, A secondary demodulator 50, a secondary modulator 52, and a primary modulator 54 are included.

  First, the structure with which the base station 12 is provided is demonstrated based on FIG.

  The antennas 20-1 and 20-2 receive a radio signal from the mobile station 14 and output the received radio signal to the radio communication unit 22. Further, the antennas 20-1 and 20-2 transmit a radio signal supplied from the radio communication unit 22 to the mobile station 14.

  The wireless communication unit 22 includes a low noise amplifier, a power amplifier, a frequency converter, a band pass filter, an A / D converter, and a D / A converter. The radio communication unit 22 amplifies the radio signals input from the antennas 20-1 and 20-2 with a low noise amplifier, then down-converts the radio signals into intermediate frequency signals, converts them to digital signals, and then converts them to a primary demodulation unit. 24. The radio communication unit 22 converts the digital signal input from the primary modulation unit 36 into an analog signal, then up-converts the digital signal into a radio signal, amplifies it to a transmission output level with a power amplifier, and then transmits the antenna 20-1. , 20-2.

  The primary demodulator 24 includes an FFT (Fast Fourier Transform) unit and a serial-parallel converter. The primary demodulator 24 performs GI (Guard Interval) removal, serial parallel conversion, discrete Fourier transform, etc. on the digital signal input from the radio communication unit 22 and concatenates the obtained complex symbols for each PRU. The complex symbol sequence concatenated for each PRU is output to the weight calculation unit 26.

  Based on the complex symbol sequence input from the primary demodulator 24, the weight calculator 26 directs the antennas 40-1 and 40-2 of the mobile station 14 toward the antenna 40 by space division multiplexing. The transmission weight for forming the sex pattern by the antennas 20-1 and 20-2 is calculated. In the present embodiment, the mobile station 14 transmits a plurality of known (here, two types) reference symbols (training symbols) having low correlation from the antennas 40-1 and 40-2 at the same frequency and at the same timing, Assume that the base station 12 receives the two types of reference symbols respectively transmitted from the antennas 40-1 and 40-2 of the mobile station 14 by the antennas 20-1 and 20-2. In this way, the weight calculation unit 26 uses the antennas 40-1 and 40-2 of the mobile station 14 based on the reference symbols received by the antennas 20-1 and 20-2 and the two known reference symbols. For each of the above, it is possible to calculate a reception weight for forming a directivity pattern in which a main beam is directed to the antenna 40 and a null is directed to the antennas 40 other than the antenna 40. An algorithm such as LMS (Least Mean Square) or RLS (Recursive Least Squares) is used for the calculation of the reception weight. Then, the weight calculator 26 multiplies the calculated complex conjugate of the reception weight by the calibration vector (calibration information) measured in advance as the transmission weight.

  The secondary demodulator 28 performs channel estimation, channel equalization, soft bit processing, deinterleaving, depuncturing, FEC (Forward Error Correction) on the complex symbol sequence weighted and synthesized with the complex conjugate of the reception weight. Demodulation such as descrambling and CRC (Cyclic Redundancy Check) is performed, and the demodulated received data is output to an upper layer (MAC layer) not shown.

  The secondary modulation unit 30 performs modulation processing such as CRC code addition, scrambling, convolutional coding, puncturing, interleaving, and constellation mapping on transmission data addressed to the mobile station 14 input from an upper layer (MAC layer). The modulated transmission data (complex symbol sequence) is output to the MIMO precoding unit 32.

  The MIMO precoding unit 32 performs predetermined MIMO precoding such as the STBC method or the SM method on the transmission data input from the secondary modulation unit 30, thereby transmitting the transmission data to the antenna 40-of the mobile station 14. 1 and 40-2 are converted into a plurality of (in this case, two) data streams. The MIMO precoding unit 32 then outputs these two data streams to the weighting synthesis unit 34.

  The weighting synthesis unit 34 weights each of the two data streams input from the MIMO precoding unit 32 with the transmission weight calculated for the antenna 40 of the mobile station 14 corresponding to the data stream, and weighted data By combining the streams for each antenna 20, a plurality (two in this case) of combined data streams respectively supplied to the antennas 20-1 and 20-2 are generated. Then, the weighting synthesizer 34 outputs these two synthesized data streams to the primary modulator 36.

  The primary modulation unit 36 includes an IFFT (Inverse Fast Fourier Transform) unit and a parallel-serial converter. The primary modulation unit 36 performs inverse discrete Fourier transform, parallel-serial conversion, GI addition, and the like on the combined data stream input from the weighting combining unit 34, and outputs the obtained digital signal to the wireless communication unit 22.

  Here, when the MIMO precoding unit 32 performs STBC-type MIMO precoding and when the MIMO precoding unit 32 performs SM-type MIMO precoding, the configuration relating to MIMO precoding and weighting synthesis is further improved. This will be specifically described.

  FIG. 7 is a diagram illustrating a configuration relating to STBC MIMO precoding and weighting synthesis. As shown in the figure, transmission data output from the secondary modulation unit 30 is subjected to STBC MIMO precoding by a MIMO precoding unit 32 and converted into two data streams 1 and 2. The data streams 1 and 2 are transmitted toward the antennas 40-1 and 40-2 of the mobile station 14, respectively.

  Here, if the transmission data input to the MIMO precoding unit 32 is S (t) and the data streams 1 and 2 output from the MIMO precoding unit 32 are X1 (t) and X2 (t), respectively, X1 (T) and X2 (t) are expressed by the following equation (1).

  Next, the data streams 1 and 2 output from the MIMO precoding unit 32 are weighted and synthesized by the weighting synthesis unit 34. That is, in the data stream 1, the transmission weight WTX1 (directivity pattern directed to the antenna 40-1 for the antenna 40-1 of the mobile station 14 calculated by the weight calculation unit 26 is formed by the antennas 20-1 and 20-2. Transmission weight for transmission). In addition, the data stream 2 is formed by the transmission weight WTX2 (directivity pattern directed to the antenna 40-2 by the antennas 20-1 and 20-2) for the antenna 40-2 of the mobile station 14 calculated by the weight calculation unit 26. Transmission weight for transmission). The weighted data streams 1 and 2 are combined for each antenna 20 to generate combined data streams 1 and 2 supplied to the antennas 20-1 and 20-2, respectively.

  The combined data streams 1 and 2 are transmitted from the antennas 20-1 and 20-2 via the primary modulation unit 36, respectively. As a result, the data stream 1 is mainly received by the antenna 40-1 of the mobile station 14, and the data stream 2 is mainly received by the antenna 40-2.

  On the other hand, FIG. 8 is a diagram showing a configuration related to SM-based MIMO precoding and weighting synthesis. As shown in the figure, transmission data output from the secondary modulation unit 30 is subjected to SM MIMO precoding by the MIMO precoding unit 32 and converted into two data streams 1 and 2. The data streams 1 and 2 are transmitted toward the antennas 40-1 and 40-2 of the mobile station 14, respectively.

  Here, the transmission data input to the MIMO precoding unit 32 are S1 (t) and S2 (t), and the data streams 1 and 2 output from the MIMO precoding unit 32 are X1 (t) and X2 (t, respectively. ), X1 (t) and X2 (t) are expressed by the following equation (2).

  Note that the processing after the MIMO precoding unit 32 is the same as that in the STBC scheme, and therefore the description thereof is omitted here.

  Next, the structure with which the mobile station 14 is provided is demonstrated based on FIG.

  The antennas 40-1 and 40-2 receive a radio signal from the base station 12 and output the received radio signal to the radio communication unit 42. Further, the antennas 40-1 and 40-2 transmit the radio signal supplied from the radio communication unit 42 to the base station 12.

  The wireless communication unit 42 includes a low noise amplifier, a power amplifier, a frequency converter, a band pass filter, an A / D converter, and a D / A converter. The radio communication unit 42 amplifies the radio signals input from the antennas 40-1 and 40-2 with a low noise amplifier, then down-converts the radio signals into intermediate frequency signals, converts them to digital signals, and then converts them to a primary demodulation unit. 44. The radio communication unit 42 converts the digital signal input from the primary modulation unit 54 into an analog signal, up-converts the signal to a radio signal, amplifies it to a transmission output level with a power amplifier, and then transmits the antenna 40-1. , 40-2.

  The primary demodulator 44 includes an FFT unit and a serial / parallel converter. The primary demodulator 44 performs GI removal, serial parallel conversion, discrete Fourier transform, and the like on the digital signal input from the wireless communication unit 42 and concatenates the obtained complex symbols for each subchannel. The complex symbol sequence concatenated every time is output to the channel calculation unit 46.

  Based on the complex symbol sequence input from the primary demodulation unit 44, the channel calculation unit 46 is configured to provide a radio propagation path (a base station 12 assigned to the mobile station 14) between the base station 12 and the mobile station 14. PRU) characteristics are estimated. In the present embodiment, it is assumed that the base station 12 transmits a data stream including a known control symbol (pilot symbol) via each PRU assigned to the mobile station 14. In this way, the channel calculation unit 46 is interposed between the base station 12 and the mobile station 14 based on the combined data stream received by the antennas 40-1 and 40-2 and the known control symbol. The characteristics of the radio propagation path can be estimated.

  For example, the radio signals transmitted from the antennas 20-1 and 20-1 of the base station 12 are X1 (t) and X2 (t), respectively, and the radio signals received by the antennas 40-1 and 40-2 of the mobile station 14 are obtained. If the signals are Y1 (t) and Y2 (t), respectively, a propagation path matrix H indicating the characteristics of the wireless propagation path interposed between the base station 12 and the mobile station 14 (the subscript on the left side of each element is the mobile station) 14 antennas 40, and the subscript on the right side indicates the antenna 20 of the base station) is expressed by the following equation (3).

  In order to obtain the propagation path matrix H with high accuracy, it is desirable to generate a data stream so that known control symbols are arranged as uniformly as possible in each PRU. FIG. 9 is a diagram showing an example of a detailed structure of a PRU when one time slot has a time width of 21 symbols (including card time) and one subchannel includes 24 subcarriers (including guard bands). It is. For example, as shown in FIG. 9, a plurality of control symbols may be included in each of data stream 1 mainly received by antenna 40-1 and data stream 2 mainly received by antenna 40-2. Control symbols may be distributed between data symbols addressed to the mobile station 14.

  The MIMO decoding unit 48 performs transmission to the mobile station 14 by performing MIMO decoding corresponding to MIMO precoding performed by the base station 12 on the combined data stream received by the antennas 40-1 and 40-2. Acquire data as received data. MIMO decoding section 48 outputs the received data to secondary demodulation section 50.

  For example, when base station 12 performs STBC MIMO precoding, radio signals Y1 (t) and Y2 (t) received by antennas 40-1 and 40-2, respectively, and transmissions addressed to mobile station 14 Between the data S1 (t) and S2 (t), the relationship of the following equation (4) derived from the equations (1) and (3) is established. For this reason, the MIMO decoding unit 48 can acquire transmission data from the base station 12 as reception data by substituting the channel matrix H obtained by the channel calculation unit 46 into Equation (4).

  On the other hand, when SM-based MIMO precoding is performed in the base station 12, radio signals Y1 (t) and Y2 (t) received by the antennas 40-1 and 40-2, respectively, and transmission to the mobile station 14 The relationship of the following equation (5) derived from the equations (2) and (3) is established between the data S1 (t) and S2 (t) (here, a ZF (Zero Forcing) algorithm is applied) ). For this reason, the MIMO decoding unit 48 can acquire transmission data from the base station 12 as reception data by substituting the propagation path matrix H obtained by the channel calculation unit 46 into Equation (5).

  The secondary demodulator 50 performs demodulation processing such as soft bit processing, deinterleave, depuncture, FEC, CRC, etc. on the received data input from the MIMO decoder 48, and the demodulated received data is not shown in an upper layer. To (MAC layer).

  The secondary modulation unit 52 adds CRC code, scrambles, convolutional coding, puncture, interleave, constellation mapping, symbol mapping, etc. to transmission data addressed to the base station 12 input from the higher layer (MAC layer). The modulated transmission data (complex symbol sequence) is output to the primary modulation unit 54.

  The primary modulation unit 54 includes an IFFT unit and a parallel-serial converter. The primary modulation unit 54 performs inverse discrete Fourier transform, parallel-serial conversion, GI addition, etc. on the modulated transmission data input from the secondary modulation unit 52, and sends the obtained digital signal to the wireless communication unit 42. Output.

  Next, operations of the base station 12 and the mobile station 14 will be described.

  FIG. 10 is a sequence diagram illustrating an example of a wireless communication method in the wireless communication system 10. Here, the data transmission processing from the base station 12 to the mobile station 14 performed for each slot or a plurality of slots will be mainly described.

  As shown in FIG. 10, the mobile station 14 transmits two kinds of known reference symbols (for weight calculation) having low correlation with the data symbols from the antennas 40-1 and 40-2 at the same frequency and the same timing, respectively. (S100). On the other hand, the base station 12 receives the two types of reference symbols transmitted from the antennas 40-1 and 40-2 of the mobile station 14 through the antennas 20-1 and 20-2.

  Next, the base station 12 determines each of the antennas 40-1 and 40-2 of the mobile station 14 based on the reference symbols received by the antennas 20-1 and 20-2 and two known types of reference symbols. , A transmission weight for forming a directivity pattern directed to the antenna 40 by space division multiplexing is calculated (S102).

  Next, the base station 12 performs secondary modulation processing on the transmission data addressed to the mobile station 14 (S104), and performs MIMO precoding on the modulated transmission data, thereby transmitting the transmission data to the mobile station 14 Conversion into two data streams respectively corresponding to the antennas 40-1 and 40-2 (S106). This data stream includes known control symbols (for propagation path characteristic estimation) in addition to data symbols. Thereafter, the base station 12 weights each of the two data streams with a transmission weight calculated for the antenna 40 of the mobile station 14 corresponding to the data stream, and combines the two weighted data streams for each antenna 20. Thus, two combined data streams respectively supplied to the antennas 20-1 and 20-2 are generated (S108).

  Then, the base station 12 performs primary modulation processing such as inverse discrete Fourier transform on the two combined data streams (S110), and these two combined data streams including the control symbol and the data symbol are transmitted to the antennas 20-1, 20-. 2 from each (S112). On the other hand, the mobile station 14 receives the two combined data streams respectively transmitted from the antennas 20-1 and 20-2 of the base station 12 by the antennas 40-1 and 40-2. Actually, one of the two data streams is mainly received by the antenna 40-1 and the other is mainly received by the antenna 40-2 due to the beamforming effect by the weighted combining process in S108.

  Next, the mobile station 14 performs primary demodulation processing such as discrete Fourier transform on the combined data stream received by the antennas 40-1 and 40-2 (S114). Further, the mobile station 14 is configured to transmit a radio propagation path interposed between the base station 12 and the mobile station 14 based on the combined data stream received by the antennas 40-1 and 40-2 and a known control symbol. The characteristics of each PRU assigned to the mobile station 14 by the base station 12 are estimated (S116). Thereafter, the mobile station 14 performs MIMO decoding on the combined data stream received by the antennas 40-1 and 40-2 based on the estimated characteristics of the radio propagation path, thereby transmitting to the mobile station 14. Data is acquired as received data (S118). Then, the mobile station 14 performs secondary demodulation processing on the received data subjected to MIMO decoding (S120).

  According to the radio communication system 10 described above, when the fluctuation of the radio propagation path interposed between the base station 12 and the mobile station 14 is small, a beam forming gain based on the directivity pattern formed by the base station 12 can be obtained. It becomes easy. This beamforming gain exceeds the MIMO reception combining gain obtained by the conventional MIMO system in which transmission is omnidirectional. On the other hand, when the fluctuation of the radio propagation path is large, it is difficult to obtain the beam forming gain due to the disturbance of the directivity pattern, but instead, it is possible to obtain the MIMO reception combined gain equivalent to the conventional MIMO scheme. For this reason, as shown in FIG. 4, the MIMO reception characteristic in the mobile station 14 can be improved particularly when the fluctuation of the radio propagation path interposed between the base station 12 and the mobile station 14 is small.

  The present invention is not limited to the above embodiment.

  For example, in the above embodiment, the base station 12 is a transmission device and the mobile station 14 is a MIMO reception device. However, the mobile station 14 may be a transmission device and the base station 12 may be a MIMO reception device. Further, at least one of the number of antennas of the base station 12 and the number of antennas of the mobile station 14 may be three or more.

  Further, the antenna interval on the transmission device side may be wider than the antenna interval on the MIMO reception device side. By so doing, the antenna correlation on the transmitting device side becomes lower than the antenna correlation on the MIMO receiving device side, so that the beamforming effect is more easily exhibited and the MIMO reception characteristics can be further improved.

  Further, the present invention is not limited to the STBC-MIMO scheme and the SM-MIMO scheme, and can be applied to all wireless communication systems that employ a MIMO scheme that performs MIMO precoding on transmission data.

10 wireless communication system, 12 base station, 14 mobile station, 20, 40 antenna, 22, 42 wireless communication unit, 24, 44 primary demodulation unit, 26 weight calculation unit, 28, 50 secondary demodulation unit, 30, 52 2 Next modulation unit, 32 MIMO precoding unit, 34 Weighting synthesis unit, 36, 54 Primary modulation unit, 46 channel calculation unit, 48 MIMO decoding unit

Claims (3)

Multiple transmit antennas,
For each of a plurality of receiving antennas of the receiving device, weight calculating means for calculating a transmission weight for forming a directivity pattern directed to the receiving antenna by the plurality of transmitting antennas;
Receiving means for receiving a plurality of known reference symbols having low correlation with each other transmitted by the plurality of receiving antennas at the same frequency and at the same timing;
The weight calculating means directs a main beam to the receiving antenna and a null to a receiving antenna other than the receiving antenna for each of the plurality of receiving antennas based on reference symbols received by the plurality of transmitting antennas. A transmission device for calculating a transmission weight for forming a sex pattern.   2. A transmission means for weighting a data stream corresponding to the reception antenna with the calculated transmission weight, combining the weighted data stream for each transmission antenna, and transmitting the data stream from each of the plurality of transmission antennas. The transmitting device according to 1. Multiple transmit antennas,
For each of a plurality of receiving antennas of the receiving device, weight calculating means for calculating a transmission weight for forming a directivity pattern directed to the receiving antenna by the plurality of transmitting antennas;
In the wireless communication method of the transmission device, comprising: means for receiving a plurality of known reference symbols having low correlation with each other transmitted by the plurality of reception antennas at the same frequency and at the same timing;
Directing a main beam to the receiving antenna for each of the receiving antennas based on reference symbols received by the transmitting antennas;
Calculating a transmission weight for forming a directivity pattern in which nulls are directed to reception antennas other than the reception antenna.

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