JP2014241475A - Transmission device, reception device and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce property deterioration of an entire MIMO system in the case where a property is deteriorated only in a transmission line where an OFDM signal of a specific system is passed, in the MIMO system.SOLUTION: A transmission line 1 comprises: a mapping section 11 which performs mapping to an IQ plane by implementing carrier modulation on a transmission signal and generates a modulation signal; a constellation rotation section 12 which rotates the modulation signal on the IQ plane; a division section 13 which divides I data and Q data of rotated modulation signals into (k) systems so as to transmit the I data and the Q data from different transmission antennas among (k) pieces of transmission antennas; an OFDM frame constitution section 15 which constitutes an OFDM frame by using the divided modulation signals; and an output processing section 16 which generates (k) systems of OFDM signals by adding a guard interval to a signal obtained by performing inverse Fourier transformation on a carrier symbol, and outputs the OFDM signals to the (k) pieces of transmission signals, respectively.

Description

  The present invention relates to a transmitter that transmits an OFDM (Orthogonal Frequency Division Multiplexing) signal, a receiver that receives an OFDM signal, and a program thereof in a multiple input multiple output (MIMO) system.

  In the field of wireless transmission, there is a growing demand for an increase in transmission capacity in order to enable large-capacity content services. As a technique that meets such a demand, there is a technique called SDM (Space Division Multiplexing) that uses a plurality of modulated waves in the same frequency band and spatially multiplexes and transmits different information. For example, in the case of a 2 × 2 MIMO system configured using two transmission antennas and two reception antennas, transmission capacity can be increased by transmitting two uncorrelated OFDM signals from the two transmission antennas. Can be doubled.

  In a MIMO system to which SDM is applied, while transmission capacity increases, signals in the same frequency band become interference waves with each other, and transmission characteristics may deteriorate. For this reason, methods for improving transmission characteristics are being actively studied.

  In a 2 × 2 MIMO system to which SDM is applied, an uncorrelated OFDM signal is transmitted from two transmission antennas, passes through different propagation paths, and reaches each of two reception antennas. When the characteristics of the road are deteriorated, the characteristics of the entire MIMO system are deteriorated. Thus, a technique is known in which transmission data is interleaved between OFDM signals transmitted from two transmission antennas to improve transmission characteristics (see, for example, Non-Patent Document 1).

  In the conventional mapping used in ISDB-T, the terrestrial digital television broadcasting standard in Japan, if the bit string to be transmitted is N bits per symbol, N / 2 bits are expressed by I-axis coordinates, and the rest N / 2 bits are expressed by the coordinates of the Q axis (see Non-Patent Document 2). For this reason, when a large noise is added to the value of one axis and the value becomes 0, for example, N / 2-bit data to be transmitted by the value of the one axis is received on the receiving side. It cannot be restored. Note that mapping means assigning to complex numbers on the IQ plane in order to transmit 0 and 1 bit strings.

  In response to this problem, the latest digital terrestrial television broadcasting standard DVB-T2 in Europe standardizes a mapping improvement method called constellation rotation (see Non-Patent Document 3). In the constellation rotation, an operation of rotating a constellation (that is, signal point arrangement) in which a bit string is assigned to the coordinates of the IQ axis by conventional mapping is performed.

  By rotating the constellation, even if noise is added to the value of one of the IQ axes and the value becomes small, the signal point can be identified from the value of the other axis. That is, when the bit string to be transmitted is N bits, even when a large noise is added to one of the IQ axes, N-bit data can be restored from the value of the other axis.

Asakura and four others, "Transmission technology for next-generation terrestrial broadcasting-A study of multidimensional interleaving-", IEICE Technical Report, February 2012, Vol. 36, No. 6, P.53- 58 "Transmission method for digital terrestrial television broadcasting", ARIB STD-B31, 2.1st edition, The Japan Radio Industry Association, December 18, 2012 “ETSI IN 302 755 V1.3.1 (2012-04)”, [online], [Search April 22, 2015], Internet <URL: http://www.etsi.org/deliver/etsi_en/302700_302799/302755 /01.03.01_60/en_302755v010301p.pdf>

  Consider a case where two uncorrelated OFDM signals are transmitted from two transmitting antennas in a 2 × 2 MIMO system to which SDM is applied. At this time, by applying the constellation rotation to the two modulation signals, the transmission characteristics are improved as compared with the case where the constellation rotation is not applied. However, for example, when one transmit antenna transmits an OFDM signal by horizontal polarization and the other transmit antenna transmits an OFDM signal by vertical polarization, the transmission characteristics of the two are different, and therefore, they are transmitted from one transmit antenna. The transmission characteristics of only data may be deteriorated. In such a case, the characteristics of the entire MIMO system are deteriorated. In an extreme example, when one of the two systems of OFDM signals cannot be received at all, half of the bit string cannot be restored.

  Therefore, an object of the present invention made in view of such a point is to reduce the characteristic deterioration of the entire MIMO system when the characteristic of only the transmission path through which the OFDM signal of a specific system passes deteriorates in the MIMO system. It is to provide a transmission device, a reception device, and a program that can be used.

  In order to solve the above-described problem, a transmission apparatus according to the present invention is a transmission apparatus that transmits an OFDM signal in a MIMO system, performs carrier modulation on the transmission signal, performs mapping on the IQ plane, and generates a modulation signal A mapping unit, a constellation rotating unit that rotates the modulated signal on an IQ plane, and I data and Q data of each modulated signal rotated by the constellation rotating unit are transmitted differently from among the k transmitting antennas. A division unit that divides the signal into k systems so as to be transmitted from an antenna; an OFDM frame configuration unit that forms an OFDM frame composed of a predetermined number of carrier symbols using the modulation signal after division by the division unit; and the carrier symbol OFDM signal with guard interval added to signal obtained by inverse Fourier transform Form, characterized in that and an output processing unit that outputs to each of the k transmit antennas.

  Furthermore, the transmission apparatus according to the present invention further includes an interleaving unit that rearranges and interleaves the modulated signals divided by the dividing unit and outputs the result to the OFDM frame configuration unit.

  Furthermore, in the transmission apparatus according to the present invention, the interleaving unit rearranges the k-system modulation signals divided by the division unit according to different procedures for each system.

  In order to solve the above problems, a receiving apparatus according to the present invention is a receiving apparatus that receives an OFDM signal in a MIMO system, removes a guard interval of the received OFDM signal, performs a Fourier transform process, and generates a carrier symbol. An input processing unit to generate, a transmission channel response estimation unit that estimates a transmission channel response of the carrier symbol, a MIMO detection unit that generates modulation signals of k systems using the carrier symbol and the transmission channel response, and the k Selects and synthesizes I and Q data from the modulation signal of the system, generates a new modulation signal, and demodulates the modulation signal synthesized by the synthesizer and outputs bit stream or bit likelihood information And a demapping unit.

  Furthermore, the receiving apparatus according to the present invention further includes a deinterleaving unit that rearranges the modulated signals generated by the MIMO detection unit, performs deinterleaving processing, and outputs the result to the synthesizing unit.

  Furthermore, the receiving apparatus according to the present invention is characterized in that the deinterleaving unit rearranges k modulation signals generated by the MIMO detection unit according to different procedures for each system.

  Moreover, in order to solve the said subject, the program concerning this invention makes a computer function as said transmission apparatus, It is characterized by the above-mentioned.

  In order to solve the above problems, a program according to the present invention causes a computer to function as the receiving device.

  According to the present invention, in the MIMO system, when the characteristics of the transmission path through which the OFDM signal of a specific system passes deteriorates, the characteristic deterioration of the entire MIMO system can be reduced. For example, even when the first system OFDM signal cannot be received at all among the two systems of OFDM signals, if only the second system OFDM signal can be received correctly, the entire bit string can be restored.

It is a block diagram which shows the structural example of the transmitter which concerns on one Embodiment of this invention. It is a figure explaining operation | movement of the constellation rotation part in the transmitter which concerns on one Embodiment of this invention. It is a figure explaining the effect by the interleaving part in the transmitter which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the receiver which concerns on one Embodiment of this invention. It is a block diagram which shows the structural example of the transmitter which concerns on another embodiment of this invention. It is a block diagram which shows the structural example of the receiver which concerns on another embodiment of this invention.

  Hereinafter, after describing a transmitting apparatus according to an embodiment of the present invention, a receiving apparatus will be described. In the following, a 2 × 2 MIMO system to which SDM is applied will be mainly described. However, the present invention is not limited to the 2 × 2 MIMO system. For example, the present invention is similarly applied to a 4 × 4 MIMO system or a 2 × 4 MIMO system. The invention can be applied.

[Transmitter]
FIG. 1 is a block diagram illustrating a configuration example of a transmission apparatus according to an embodiment of the present invention. In the example illustrated in FIG. 1, the transmission apparatus 1 includes a mapping unit 11, a constellation rotation unit 12, a division unit 13, k interleave units 14 (14-1 and 14-2), and k OFDM units. It comprises a frame configuration unit 15, k output processing units 16 (16-1, 16-2), and k transmission antennas 17 (17-1, 17-2). In the case of a 2 × 2 MIMO system, k = 2.

  The mapping unit 11 performs carrier modulation on the bit stream of the transmission signal and performs mapping on the IQ plane as N bits / symbol. Then, a modulation signal including a set of I data and Q data is generated and output to the constellation rotating unit 12.

  The constellation rotating unit 12 rotates the modulation signal generated by the mapping unit 11 by a predetermined angle on the IQ plane and outputs the rotated signal to the dividing unit 13. FIG. 2 is a diagram for explaining the operation of the constellation rotating unit 12 by taking QPSK modulation as an example. FIG. 2A shows the constellation before rotation. Before rotation of the constellation, when noise is added to the value of the Q axis and the value becomes small, it becomes difficult to identify the signal points a and b and the signal points c and d. FIG. 2B shows the constellation after rotation. After rotation of the constellation, even if noise is added to the Q-axis value and the value becomes small, the signal point can be identified from the I-axis value. Similarly, even when noise is added to the I-axis value and the value becomes smaller, the signal point can be identified from the Q-axis value.

  The dividing unit 13 divides the I data and Q data of each modulated signal rotated by the constellation rotating unit 12 into k systems so as to be transmitted from different transmission antennas 17.

In this embodiment, since k = 2 (two transmission antennas 17), the input modulation signal sequence (I, Q) is changed to the first system modulation signal sequence (I ⁽¹⁾ , Q ⁽¹⁾ ). And divided into a second series of modulated signal strings (I ⁽²⁾ , Q ⁽²⁾ ) and output. If (I, Q) = (I ₀ , Q ₀ ), (I ₁ , Q ₁ ),..., For example, the modulation signal is expressed by equations (1), (2), (3), (4), ( 1) Divide as shown in (4) or (2) and (3).
(I ⁽¹⁾ , Q ⁽¹⁾ ) = (I ₀ , I ₁ ), (I ₂ , I ₃ ) (1)
(I ⁽²⁾ , Q ⁽²⁾ ) = (Q ₀ , Q ₁ ), (Q ₂ , Q ₃ ) (2)
(I ⁽¹⁾ , Q ⁽¹⁾ ) = (I ₁ , I ₀ ), (I ₃ , I ₂ ) (3)
(I ⁽²⁾ , Q ⁽²⁾ ) = (Q ₁ , Q ₀ ), (Q ₃ , Q ₂ ) (4)

The dividing unit 13 may also divide the modulated signal as shown in the equations (5), (6), (7), (8), (5), (8), or (6), (7). Good.
(I ⁽¹⁾ , Q ⁽¹⁾ ) = (I ₀ , Q ₁ ), (I ₂ , Q ₃ ) (5)
(I ⁽²⁾ , Q ⁽²⁾ ) = (I ₁ , Q ₀ ), (I ₃ , Q ₂ ) (6)
(I ⁽¹⁾ , Q ⁽¹⁾ ) = (Q ₁ , I ₀ ), (Q ₃ , I ₂ ) (7)
(I ⁽²⁾ , Q ⁽²⁾ ) = (Q ₀ , I ₁ ), (Q ₂ , I ₃ ) (8)

  Although the interleave unit 14 is not an essential component, the transmission characteristic can be improved by providing the interleave unit 14. The interleaving unit 14 rearranges the modulated signals divided by the dividing unit 13 and outputs the result to the OFDM frame configuration unit 15. For example, the interleave unit 14 includes a time interleave unit 141 and a frequency interleave unit 142 as shown in FIG.

Time interleaving section 141 rearranges the order of the modulated signals divided by dividing section 13 in the time direction, performs interleaving processing, and outputs the result to frequency interleaving section 142.
The frequency interleaving unit 142 rearranges the order of the modulation signals interleaved in the time direction by the time interleaving unit 141 in the frequency direction, performs interleaving processing, and outputs the result to the output processing unit 16.

  The procedure for rearranging the interleave unit 14 is not limited. However, it is preferable to rearrange the interleave units 14-1 and 14-2 according to different procedures. Rearranging according to different procedures means that when the same modulated signal is input to the interleave units 14-1 and 14-2, the modulated signals output from the interleave units 14-1 and 14-2 are different from each other. The reason why the transmission characteristics can be further improved by rearranging the interleave units 14-1 and 14-2 according to different procedures will be described below.

FIG. 3 is a diagram illustrating the effect of the interleave unit 14. First, consider a case where the interleave units 14-1 and 14-2 rearrange the modulated signals according to the same procedure. When the OFDM frame configuration unit 15 performs OFDM frame configuration by sequentially allocating the modulation signals input from the interleaving unit 14 from the left carrier, the carrier symbols corresponding to the two modulation signals are arranged as shown in FIG. become. Here, it is assumed that modulated signals (I ₀ , I ₁ ) and (Q ₀ , Q ₁ ) are transmitted by carriers located at the same frequency (carrier number). At this time, if large noise is added to the second carrier from the left side due to frequency selective fading, both of the modulation signals (I ₂ , I ₃ ) and (Q ₂ , Q ₃ ) receive noise. In such a case, N bits assigned to the modulation signals (I ₂ , Q ₂ ) output from the constellation rotation unit 12 and N bits assigned to the modulation signals (I ₃ , Q ₃ ) are both noises. 2N bits cannot be restored on the receiving side.

On the other hand, FIG. 3B shows a case where the interleave units 14-1 and 14-2 rearrange the modulated signals according to different procedures. If large noise is added to the second carrier from the left side due to frequency selective fading, the modulated signals (I ₀ , I ₃ ) and (Q ₈ , Q ₁ ) will receive noise. Here, considering N bits assigned to the modulation signals (I ₃ , Q ₃ ) output from the constellation rotation unit 12, even when I ₃ cannot be received due to frequency selective fading, Q ₃ is different from each other. If the signal can be received correctly from the carrier, the N bits assigned to the modulated signal (I ₃ , Q ₃ ) can be restored. As described above, it is preferable that the interleave units 14-1 and 14-2 perform data rearrangement according to different procedures.

  The OFDM frame configuration unit 15 inserts a pilot signal (SP signal, CP signal), a TMCC signal indicating control information, and an AC signal indicating additional information into the modulated signal rearranged by the interleaving unit 14, and a predetermined number of carriers. An OFDM frame composed of symbols is constructed and output to the output processing unit 16.

  The output processing unit 16 generates an OFDM signal obtained by adding a guard interval to a signal obtained by performing inverse Fourier transform on the carrier symbol generated by the OFDM frame configuration unit 15. More specifically, the output processing unit 16 includes an inverse Fourier transform unit 161 (161-1 and 161-2), a GI (Guard interval) addition unit 162 (162-1 and 162-2), and an orthogonal modulation unit 163. (163-1 and 163-2) and a D / A conversion unit 164 (164-1 and 164-2).

  The inverse Fourier transform unit 161 performs an inverse Fourier transform process (for example, inverse fast Fourier transform) on the carrier symbol generated by the OFDM frame configuration unit 15 to generate a time-domain effective symbol signal, and a GI addition unit It outputs to 162.

  The GI adding unit 162 generates a baseband signal by inserting a guard interval obtained by copying the latter half of the effective symbol signal at the head of the effective symbol signal generated by the inverse Fourier transform unit 161, and outputs the baseband signal to the quadrature modulation unit 163. To do.

  The quadrature modulation unit 163 performs orthogonal modulation processing on the baseband signal generated by the GI addition unit 162 to generate an OFDM signal.

  The D / A conversion unit 164 converts the OFDM signal generated by the orthogonal modulation unit 163 into an analog signal and transmits the analog signal via the transmission antenna 17.

[Receiver]
Next, a receiving apparatus that receives an OFDM signal transmitted from the transmitting apparatus 1 will be described.

  FIG. 4 is a block diagram illustrating a configuration example of a receiving apparatus according to an embodiment of the present invention. In the example illustrated in FIG. 4, the receiving device 2 includes one receiving antenna 21 (21-1 and 21-2), one input processing unit 22 (22-1 and 22-2), and a transmission path response. An estimation unit 23, a MIMO detection unit 24, l deinterleave units 25, a synthesis unit 26, and a demapping unit 27 are provided. For a 2 × 2 MIMO system, l = 2. Note that, when the transmission device 1 does not include the interleaving unit 14, the reception device 2 does not need to include the deinterleaving unit 25.

  The input processing unit 22 (22-1 and 22-2) receives the OFDM signal transmitted from the transmission device 1 corresponding to the reception device 2 via the reception antenna 21 (21-1 and 21-2), The guard interval of the received OFDM signal is removed, and a Fourier transform process is performed to generate a carrier symbol. More specifically, the input processing unit 22 includes an A / D conversion unit 221 (221-1 and 221-2), an orthogonal demodulation unit 222 (222-1 and 222-2), and a GI removal unit 223 (223-). 1 and 223-2) and a Fourier transform unit 224 (224-1 and 224-2).

  The A / D conversion unit 221 performs A / D conversion on the OFDM signal received from the transmission apparatus 1 and outputs the result to the orthogonal demodulation unit 222.

  The orthogonal demodulator 222 performs orthogonal demodulation processing on the OFDM signal digitally converted by the A / D converter 221 to generate a baseband signal, and outputs the baseband signal to the GI remover 223.

  The GI removal unit 223 extracts the effective symbol signal by removing the guard interval from the baseband signal generated by the orthogonal demodulation unit 222 and outputs the effective symbol signal to the Fourier transform unit 224.

  The Fourier transform unit 224 performs a Fourier transform process (for example, fast Fourier transform) on the effective symbol signal extracted by the GI removal unit 223 to generate a frequency-domain carrier symbol (complex baseband signal) for transmission. It outputs to the road response estimation part 23 and the MIMO detection part 24.

  The transmission path response estimation unit 23 extracts a pilot signal from the carrier symbol generated by the Fourier transform unit 224. Then, the transmission path response for each carrier symbol is estimated from the pilot signal and output to the MIMO detection unit 24.

  The MIMO detection unit 24 uses the carrier symbol generated by the Fourier transform unit 224 and the transmission path response estimated by the transmission path response estimation unit 23, such as ZF (Zero Forcing) and MMSE (Minimum Mean Squared Error). By using a known method, data streams received by the plurality of receiving antennas 21 are separated to generate (detect) k-system modulated signals. Then, the first system modulation signal is output to the deinterleaving unit 25-1, and the second system modulation signal is output to the deinterleaving unit 25-2.

  The deinterleaving unit 25 performs deinterleaving processing on the modulated signal generated by the MIMO detection unit 24 and outputs the result to the synthesis unit 26. For example, the deinterleaving unit 25 includes a frequency deinterleaving unit 251 and a time deinterleaving unit 252 as shown in FIG. When data is rearranged in the order of the time direction and the frequency direction in the interleave unit 14 of the transmission apparatus 1, the data is rearranged in the order of the frequency direction and the time direction in the deinterleave unit 25.

  The frequency deinterleave unit 251 rearranges the order of the modulation signals generated by the MIMO detection unit 24 in the frequency direction, performs deinterleave processing, and outputs the result to the time deinterleave unit 252. That is, the frequency deinterleaving unit 251 rearranges the modulated signals rearranged by the frequency interleaving unit 142 of the transmission device 1 so as to return to the order before the frequency interleaving process.

  The time deinterleave unit 252 rearranges the order of the modulated signals deinterleaved in the frequency direction by the frequency deinterleave unit 251 in the time direction, performs deinterleave processing, and outputs the result to the synthesis unit 26. That is, the time deinterleaving unit 252 rearranges the modulated signals rearranged by the time interleaving unit 141 of the transmission device 1 so as to return to the order before the time interleaving process.

The synthesizer 26 selects and synthesizes I data and Q data from the k-system modulated signals deinterleaved by the time deinterleaver 252 and generates a new modulated signal. That is, the combining unit 26 combines the modulated signals divided by the dividing unit 13 of the transmission apparatus 1 so as to return to the state before the division. In this embodiment, k = 2, and the synthesis unit 26 inputs the I data or Q data of the first system modulation signal input from the time deinterleave unit 252-1 and the time deinterleave unit 252-2. Then, I data or Q data of the modulated signal of the second system is synthesized to generate a new modulated signal. For example, the modulation signal train of the first system (I ⁽¹⁾ , Q ⁽¹⁾ ) = (I ₀ , I ₁ ), (I ₂ , I ₃ )..., The modulation signal train of the second system ( When I ⁽²⁾ , Q ⁽²⁾ ) = (Q ₀ , Q ₁ ), (Q ₂ , Q ₃ )..., The modulation signal sequence (I, Q) = (I ₀ , Q ₀ ), (I ₁ , Q ₁ )... Are generated.

  The demapping unit 27 demodulates the modulation signal combined by the combining unit 26, generates a bit stream of the number of symbols × N bits, and outputs the bit stream to the outside. When transmitting a bit stream encoded by an error correction code, the demapping unit 27 generates bit likelihood information for each of the number of symbols × N bits, and outputs it to the outside.

  So far, an example in which the present invention is applied to a 2 × 2 MIMO system has been described, but an example in which the present invention is applied to a 4 × 4 MIMO system will be described below.

FIG. 5 is a block diagram showing a configuration of the transmission apparatus 3 when the present invention is applied to a 4 × 4 MIMO system. The dividing unit 13 has four systems so that the I data and the Q data of each modulated signal rotated by the constellation rotating unit 12 are transmitted from different transmitting antennas among the four transmitting antennas 17-1 to 17-4. Divide into FIG. 5 shows an example of a four-division method, where an input modulation signal sequence (I ₀ , Q ₀ ), (I ₁ , Q ₁ ). Column (I ₀ , I ₂ ), (I ₄ , I ₆ )..., Second system modulation signal sequence (Q ₀ , Q ₂ ), (Q ₄ , Q ₆ ). System modulation signal string (I ₁ , I ₃ ), (I ₅ , I ₇ )..., And fourth system modulation signal string (Q ₁ , Q ₃ ), (Q ₅ , Q ₇ ),. It is divided into ・. As described above, the interleave units 14-1 to 14-4 preferably rearrange the four systems of modulation signals divided by the division unit 13 according to different procedures for each system.

  FIG. 6 is a block diagram illustrating a configuration of the receiving device 4 when the present invention is applied to a 4 × 4 MIMO system. The MIMO detection unit 24 generates (detects) four systems of modulation signals transmitted from the transmission device 3. As described above, the deinterleaving units 25-1 to 25-4 preferably rearrange the four systems of modulation signals generated by the MIMO detection unit 24 according to different procedures for each system. The synthesizer 26 selects and synthesizes I data and Q data from the four modulation signals, and generates a new modulation signal.

  As described above, in the transmission devices 1 and 3 according to the present invention, the constellation rotating unit 12 rotates the modulated signal on the IQ plane, and then the dividing unit 13 converts the I data and Q data of each modulated signal to k pieces. The transmission antennas 17 are divided into k systems so as to be transmitted from different transmission antennas. In the receiving apparatuses 2 and 4 according to the present invention, the combining unit 26 selects and synthesizes I data and Q data from k-system modulated signals, and generates a new modulated signal.

As a result, even if one of the I data and Q data of the modulation signal cannot be correctly received, the entire bit string can be restored if the other data can be correctly received. In the example of Expressions (1) and (2), for example, even when the modulation signals (I ₀ , I ₁ ) cannot be received, (Q ₀ , Q ₁ ) to (I ₀ , Since I ₁ ) can be estimated, the N bits transmitted by (I ₀ , Q ₀ ) and the N bits transmitted by (I ₁ , Q ₁ ) can be restored. Therefore, in the MIMO system to which SDM is applied, when only the characteristic of the propagation path of a specific OFDM signal is deteriorated, the characteristic deterioration of the entire system can be reduced.

  In addition, it is preferable that the transmission apparatuses 1 and 3 include the interleave unit 14 and the reception apparatuses 2 and 4 include the deinterleave unit 25. In particular, the interleaving unit 14 rearranges the k system modulation signals divided by the division unit 13 according to different procedures for each system, and the deinterleaving unit 25 systematizes the k system modulation signals generated by the MIMO detection unit 24. It is preferable to rearrange them according to different procedures.

  As a result, the reception apparatus 2 can estimate the modulation signal even when both modulation signals of the same carrier number of the OFDM modulation signals output from the plurality of transmission antennas 17 receive a large noise. Can be reduced.

  Here, a computer can be used to function as the transmission apparatuses 1 and 3, and such a computer stores a program describing processing contents for realizing each function of the transmission apparatuses 1 and 3. The program can be realized by reading out and executing the program by the CPU of the computer. This program can be recorded on a computer-readable recording medium.

  In addition, a computer can be used to function as the receiving devices 2 and 4, and such a computer stores a program describing processing contents for realizing each function of the receiving devices 2 and 4 in a storage unit of the computer. This can be realized by storing the program and executing it by the CPU of the computer. This program can be recorded on a computer-readable recording medium.

  Although the above embodiments have been described as representative examples, it will be apparent to those skilled in the art that many changes and substitutions can be made within the spirit and scope of the invention. Therefore, the present invention should not be construed as being limited by the above-described embodiments, and various modifications and changes can be made without departing from the scope of the claims. For example, a plurality of constituent blocks described in the embodiments can be combined into one, or one constituent block can be divided.

  Also, regarding the modulated signals (I, Q) after application of constellation rotation, I data and Q data are transmitted from different transmission antennas so that the I data and Q data pass through different transmission paths and arrive at the receiving apparatus. Therefore, the number of transmission antennas and the number of reception antennas are not limited to two or four. In addition, it is a general configuration to install more receiving antennas than the number of transmitting antennas in the receiving device, and when the number of receiving antennas is larger than the number of transmitting antennas, further improve the transmission characteristics by the reception diversity effect. Can do.

  As described above, according to the present invention, even when the characteristic of only the transmission path through which a specific OFDM signal passes is deteriorated, the characteristic deterioration of the entire MIMO system can be reduced. Useful for applications.

DESCRIPTION OF SYMBOLS 1,3 Transmitter 2,4 Receiver 11 Mapping part 12 Constellation rotation part 13 Dividing part 14 Interleaving part 15 OFDM frame structure part 16 Output processing part 17 Transmission antenna 21 Reception antenna 22 Input processing part 23 Transmission path response estimation part 24 MIMO detection unit 25 Deinterleaving unit 26 Combining unit 27 Demapping unit 141 Time interleaving unit 142 Frequency interleaving unit 161 Inverse Fourier transform unit 162 GI addition unit 163 Orthogonal modulation unit 164 D / A conversion unit 221 A / D conversion unit 222 Orthogonal demodulation Unit 223 GI removal unit 224 Fourier transform unit 251 frequency deinterleave unit 252 time deinterleave unit

Claims (8)

A transmitter for transmitting an OFDM signal in a MIMO system,
A mapping unit that performs carrier modulation on the transmission signal, performs mapping to the IQ plane, and generates a modulation signal;
A constellation rotating unit that rotates the modulation signal on an IQ plane;
A dividing unit that divides I data and Q data of each modulated signal rotated by the constellation rotating unit into k systems so as to be transmitted from different transmitting antennas among k transmitting antennas;
An OFDM frame configuration unit that configures an OFDM frame composed of a predetermined number of carrier symbols using the modulated signal after the division by the division unit;
An output processing unit that generates k systems of OFDM signals to which a guard interval is added to a signal obtained by performing inverse Fourier transform on the carrier symbol, and outputs the generated signals to the k transmitting antennas, respectively;
A transmission device comprising:   The transmission apparatus according to claim 1, further comprising an interleaving unit that rearranges and interleaves the modulated signals divided by the dividing unit and outputs the rearranged signal to the OFDM frame configuration unit.   The transmission apparatus according to claim 2, wherein the interleaving unit rearranges the k-system modulation signals divided by the division unit according to different procedures for each system. A receiving apparatus for receiving an OFDM signal in a MIMO system,
An input processing unit that removes the guard interval of the received OFDM signal and generates a carrier symbol by performing Fourier transform processing;
A channel response estimation unit for estimating the channel response of the carrier symbol;
A MIMO detection unit for generating k-system modulation signals using the carrier symbol and the transmission path response;
Selecting and synthesizing I data and Q data from the k-system modulation signals, and generating a new modulation signal;
A demapping unit that demodulates the modulated signal combined by the combining unit and outputs bitstream or bit likelihood information;
A receiving apparatus comprising:   The receiving apparatus according to claim 4, further comprising a deinterleaving unit that rearranges and deinterleaves the modulated signals generated by the MIMO detection unit and outputs the rearranged signal to the synthesis unit.   The receiving apparatus according to claim 5, wherein the deinterleaving unit rearranges the k modulation signals generated by the MIMO detection unit according to different procedures for each system.   A transmission program for causing a computer to function as the transmission device according to any one of claims 1 to 3.   A receiving program for causing a computer to function as the receiving device according to any one of claims 4 to 6.

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