JP2012049740A - Transmission apparatus and reception apparatus of polarized mimo-ofdm transmission system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a transmission apparatus and a reception apparatus of a polarized MIMO-OFDM transmission system using a plurality of transmission antennas and reception antennas.SOLUTION: A transmission apparatus 10 includes: a MIMO coding section 110; OFDM signal generation sections 120, 130 for generating OFDM signals for a plurality of transmission antennas; system-specific polarization control sections 140, 150 for controlling polarization of the plurality of systems of OFDM signals; a retransmission reception section 170 for receiving information on cross polarization power ratio from a receiving side; and an XPD adjustment section 160 for adjusting the cross polarization discrimination of the plurality of transmission antennas. A reception apparatus 20 includes: OFDM signal demodulation sections 210, 220 for receiving and demodulating the OFDM signals via a plurality of reception antennas including a horizontally polarized antenna and a vertically polarized antenna; a MIMO decoding section 230 for receiving the data of the OFDM signals and propagation channel response information estimated from signals acquired via the reception antennas and MIMO-separating and decoding them; and an XPR computation section 240 for computing cross polarization power ratios from the propagation channel response information.

Description

  The present invention relates to a transmitter and receiver of a polarization MIMO-OFDM transmission scheme in which an OFDM signal is wirelessly transmitted from a plurality of transmitting antennas on a transmitting apparatus side and is received by a receiving apparatus using one or a plurality of receiving antennas. Is.

  In recent years, there has been a growing demand for high-definition wireless cameras for studios with low latency, high image quality and excellent mobility. This wireless system is expected to have various effects such as a variety of shooting methods, improved safety, and fewer program set restrictions. For example, there is a great demand for wireless cameras in shooting sites such as sports broadcasts, music programs, and drama shooting. Compared with conventional cable-connected cameras, wireless cameras can not only improve camera work, but also produce various effects such as simplified setup preparation and improved safety for performers and spectators including the photographer himself. it can.

  Therefore, the development of a new wireless transmission system aimed at realizing a wireless camera that wirelessly transmits high-definition television signals with low delay and high line reliability has attracted attention. The use of “Multiple Input Multiple Output (MIMO) -OFDM transmission scheme” for transmitting OFDM signals is being studied. For example, by using millimeter-wave radio waves and MIMO-OFDM transmission technology, video transmission is not interrupted even in a studio with harsh radio wave propagation environments in which various sets are arranged, and multiple cameras are used simultaneously. In order to be able to do so, the development of a “millimeter wave mobile camera” that can move freely around the studio and take pictures is drawing attention. This MIMO-OFDM transmission system realizes space division multiplex transmission by transmitting a plurality of OFDM signals on the same frequency, expands the transmission speed to several times the number of transmission antennas, improves transmission quality, and diversity effect The required CNR can be improved.

  On the other hand, this MIMO-OFDM transmission system uses the difference in propagation path information between the transmitting and receiving antennas in order to separate and demodulate OFDM signals multiplexed on the same frequency. Therefore, there is a problem that separation and demodulation of multiplexed OFDM signals becomes difficult when there are few reflected waves such as in an outdoor line-of-sight environment and the correlation between propagation paths is high.

  Therefore, in the line-of-sight environment, in order to suppress the correlation between the propagation paths, it has been widely studied to suppress the correlation between the propagation path responses and improve the demodulation performance by using transmission / reception antennas having different polarizations.

  For example, as shown in FIG. 1, between one transmission device 10 having two transmission antennas 101-1 and 101-2 and a reception device 20 having two reception antennas 201-1 and 201-2. A wireless camera system that performs MIMO-OFDM transmission can be considered. As an OFDM signal format to be transmitted, an OFDM signal according to ARIB STD-B43 can be used.

In such a wireless camera system, MIMO-OFDM between the transmission apparatus 10 having two transmission antennas 101-1 and 101-2 and the reception apparatus 20 having two reception antennas 201-1 and 201-2 is provided. Perform transmission. In FIG. 1, the propagation path response between the transmission antenna j and the reception antenna i when the transmission antenna is j and the reception antenna i is denoted by h _ij . For example, between the two transmitting antennas 101-1 and 101-2 and the two receiving antennas 201-1 and 201-2, the case where the correlation of the channel response is high means that each channel response ( h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) means that the correlation between them is high. The transmission apparatus 10 in this case can be a mobile terminal that can move freely, and two OFDM signals with the same frequency are transmitted from the two transmission antennas 101-1 and 101-2. In addition, the pilot signal is included in the OFDM signal transmitted from the transmission apparatus 10 at the same frequency, and the reception apparatus 20 passes through each propagation path from the pilot signal received in the interference state in the reception unit of the reception apparatus 20. The propagation path characteristics thus obtained can be extracted (see, for example, Patent Document 1).

JP 2005-124125 A

  In a line-of-sight environment with few reflected waves, the correlation of propagation path responses between the transmitting and receiving antennas is high. If the correlation of each channel response becomes high, the transmission characteristics of MIMO-OFDM transmission are greatly degraded. Therefore, in order to realize MIMO-OFDM transmission in a line-of-sight environment with few reflected waves, it is necessary to suppress the correlation of the propagation path response between the propagation paths. Methods for suppressing correlation by assigning are widely known. However, although the correlation between channel responses is suppressed by assigning different polarizations to each OFDM signal, the received power of the OFDM signal is greatly reduced between the transmission antennas and reception antennas assigned different polarizations. Therefore, there is a problem that the reception diversity effect is reduced and the MIMO-OFDM transmission characteristics are deteriorated.

  In addition, in the non-line-of-sight environment where there are many reflected waves, the correlation of each channel response between the transmitting antenna and the receiving antenna takes a naturally low value, and when MIMO-OFDM transmission using polarization is performed in this environment, There is a problem in that the reception power of OFDM signal transmission between transmission antennas and reception antennas having different polarizations is greatly reduced, leading to a reduction in reception diversity effect.

  Therefore, an object of the present invention is to provide a MIMO-OFDM transmission system using a plurality of transmitting antennas and a plurality of receiving antennas, and different polarizations such as orthogonal polarizations in a line-of-sight environment, etc. When performing MIMO-OFDM transmission by assigning to each, the cross polarization power ratio measured on the reception side is used for adjusting the cross polarization characteristics of each antenna on the transmission side and / or reception side. A polarization MIMO-OFDM transmission system transmission device that efficiently suppresses path correlation and suppresses a reduction in reception diversity effect caused by using polarization, and improves MIMO-OFDM transmission characteristics; and To provide a receiving apparatus.

  The transmitting apparatus and the receiving apparatus of the polarization MIMO-OFDM transmission system according to the present invention calculate a cross polarization power ratio (XPR) on the receiving apparatus side, and obtain a result of the obtained cross polarization power ratio. Based on the above, while controlling the cross polarization discrimination (XPD) between transmitting antennas or receiving antennas at the transmitting device or the receiving device, the increase in the correlation between the propagation paths is suppressed. A decrease in reception diversity is minimized, and transmission degradation of MIMO-OFDM transmission in a line-of-sight environment is prevented.

  In general, the transmission device and the reception device of the polarization MIMO-OFDM transmission system according to the present invention use the transmission antennas or the reception antennas of different polarizations, particularly in an environment where each channel response is highly correlated. When performing MIMO-OFDM transmission, the reception device includes a cross polarization power ratio calculation unit that calculates a reception level ratio between the channel responses as a cross polarization power ratio (XPR). On the other hand, the transmission device includes an XPD adjustment unit that adjusts the cross polarization discrimination (XPD) between the transmission antennas based on the result of the cross polarization power ratio calculation unit. As a result, the correlation value between the channel responses can be adjusted to an optimum value, and the decrease in reception diversity can be minimized, and the MIMO-OFDM transmission characteristics can be improved even in a line-of-sight environment.

  In addition, even when MIMO-OFDM transmission is performed in both a non-line-of-sight environment with few reflected waves and a line-of-sight environment with many reflected waves, MIMO-OFDM transmission can be performed by adjusting the cross polarization characteristics on the transmission side or reception side. Therefore, even in an ideal non-line-of-sight environment, it is possible to suppress a decrease in reception diversity effect due to orthogonal polarization, and to prevent deterioration of transmission characteristics.

  That is, the polarization MIMO-OFDM transmission system transmission apparatus of the present invention is a polarization MIMO-OFDM transmission system transmission apparatus that transmits video information using a plurality of transmission antennas. And a MIMO encoding unit that generates the same number of complex signals as the number of transmission antennas, and an OFDM for each system that generates a plurality of OFDM signals for the plurality of transmission antennas among the complex signals generated by the MIMO encoding unit A signal generation unit, a polarization control unit for each system that controls the polarization of the OFDM signals of the plurality of systems and transmits radio waves, a transmission reception unit that receives information on the cross polarization power ratio from the reception side, and a reception And an XPD adjustment unit that adjusts the degree of cross polarization discrimination in the plurality of transmission antennas based on the information on the cross polarization power ratio.

  Further, in the transmission device of the polarization MIMO-OFDM transmission system of the present invention, the transmission antenna is configured to include a horizontal polarization transmission antenna and a vertical polarization transmission antenna assigned to each system one by one, The XPD adjustment unit is configured to transmit each of the transmission antennas capable of receiving OFDM signals corresponding to the number of transmission systems at an optimum cross polarization power ratio on the reception side based on information on the cross polarization power ratio calculated on the reception side in the return reception unit. Calculating the cross-polarization discrimination between them, determining the power distribution ratio of the OFDM signal to the horizontal and vertical components in each transmission antenna so as to satisfy the cross-polarization discrimination for each transmission system, The polarization control unit is assigned an OFDM signal whose power is adjusted.

  Further, in the transmission apparatus of the polarization MIMO-OFDM transmission system of the present invention, the transmission antenna is configured to include a horizontal polarization transmission antenna or a vertical polarization transmission antenna for each system, and the XPD adjustment unit includes: Based on the information on the cross polarization power ratio calculated on the reception side in the return reception unit, the cross polarization between the transmission antennas that can receive OFDM signals for the number of transmission systems at the optimum cross polarization power ratio on the reception side. Calculating the wave discrimination, determining the power distribution ratio of the OFDM signal to the horizontal component / vertical component in each transmission antenna so as to satisfy the cross polarization discrimination for each transmission system, and the polarization controller In contrast, the vertical polarization transmission antenna is rotated, the horizontal polarization transmission antenna is rotated, or both the vertical polarization transmission antenna and the horizontal polarization transmission antenna are rotated. Allowed, characterized in that to adjust the inclination of the transmit antennas of each system.

  Further, the polarization MIMO-OFDM transmission receiver of the present invention is a polarization MIMO-OFDM transmission receiver that receives video information using a plurality of reception antennas, and includes a horizontal polarization antenna and a vertical polarization antenna. Receive and demodulate multiple systems of OFDM signals from the transmitting side via the multiple receiving antennas including the wave antenna, estimate the channel response from the signal obtained via the receiving antenna, and estimate the channel response The OFDM signal demodulator for each receiving system that outputs the information of each of the above, the data of the OFDM signal obtained from the OFDM signal demodulator and the information of the propagation path response estimated from the signal obtained through each receive antenna Obtained from the OFDM signal demodulating unit and the MIMO decoding unit that performs MIMO separation and performs diversity combining to decode video information. From the information of the channel response and XPR calculator for calculating a cross polarization power ratio for each receiving system which is characterized by comprising a.

  Further, in the polarization MIMO-OFDM transmission system receiver of the present invention, the cross-polarization power ratio received on the transmission side is further provided with a return transmission unit for transmitting the calculated cross-polarization power ratio information to the transmission side. On the basis of the above information, the cross polarization discrimination degree of the plurality of transmission antennas is adjusted.

  In the polarization MIMO-OFDM transmission receiver of the present invention, the reception antenna is configured to include a horizontal polarization reception antenna or a vertical polarization reception antenna for each system, and the calculated cross polarization Based on the information on the wave power ratio, obtain a difference value from the cross polarization power ratio of the optimum value recorded in advance in a predetermined reference XPR recording unit, and rotate the vertical polarization receiving antenna by the difference value, or A polarization controller that rotates the horizontal polarization receiving antenna or rotates both the vertical polarization receiving antenna and the horizontal polarization receiving antenna to adjust the inclination of the receiving antenna for each system; And

  Further, in the polarization MIMO-OFDM transmission receiver according to the present invention, the XPR calculation unit calculates a propagation path response and calculates a correlation value, and calculates the correlation value and a predetermined reference correlation value recording unit. The difference from the recorded reference correlation value is obtained. When the correlation value is higher than the reference correlation value, the cross polarization power ratio is obtained. On the other hand, when the calculated correlation value is lower than the reference correlation value, the XPR A switching mechanism for switching to output the minimum absolute value is provided.

  According to the present invention, MIMO-OFDM transmission is performed by allocating different polarizations such as orthogonal polarization to each transmission / reception antenna in an outdoor line-of-sight environment, etc., in a demodulation scheme of MIMO-OFDM transmission using a plurality of transmission antennas and reception antennas. In some cases, the cross-polarization power ratio measured on the receiving side is used to adjust the XPD of each transmitting antenna on the transmitting side and the receiving side, thereby effectively suppressing the correlation of each propagation path and using the polarization. Therefore, it is possible to suppress the reduction of the reception diversity effect that occurs and to improve the MIMO-OFDM transmission characteristics.

It is a figure which illustrates the wireless camera system which performs MIMO-OFDM transmission. It is a figure which shows the result of having conducted the MIMO-OFDM transmission experiment of 2 transmission systems and 4 reception systems in a line-of-sight environment with few reflected waves. It is a figure which shows the structural example of the transmitter and receiver of a polarization MIMO-OFDM transmission system. It is a figure which shows the change of the correlation of each propagation path response by the value of cross polarization power ratio. It is a figure which shows the change of the error rate by the change of cross polarization power ratio. 1 is a block diagram illustrating a transmitter and a receiver of a polarization MIMO-OFDM transmission system according to a first embodiment of the present invention. It is a figure which shows the structural example of the XPR calculating part in the receiver of the polarization MIMO-OFDM transmission system of Example 1 which concerns on this invention. It is a figure which shows the structural example of the XPD adjustment part in the transmitter of the polarization MIMO-OFDM transmission system of Example 1 which concerns on this invention. It is explanatory drawing about the adjustment method of the cross polarization identification degree of the polarization control part in the transmitter of the polarization MIMO-OFDM transmission system of Example 1 which concerns on this invention. (A), (b) has shown the mode of the adjustment method of the angle of the antenna of the polarization MIMO-OFDM transmission system of Example 2 which concerns on this invention. It is a block diagram which shows the transmitter and receiver of the polarization MIMO-OFDM transmission system of Example 3 which concerns on this invention. (A), (b) has shown the mode of the adjustment method of the angle of the antenna of the polarization MIMO-OFDM transmission system of Example 3 which concerns on this invention. It is a block diagram of the transmitting apparatus and receiving apparatus of the polarization MIMO-OFDM transmission system of Example 4 which concerns on this invention. It is a figure which shows another example of a structure of the XPR calculating part in the receiver of the polarization MIMO-OFDM transmission system of Example 5 which concerns on this invention.

  Hereinafter, embodiments of a transmission apparatus and a reception apparatus of a polarization MIMO-OFDM transmission system using orthogonal polarization according to the present invention will be described. In the respective embodiments, the same reference numerals are given to the same constituent elements for explanation.

  First, we have conducted several experiments on the relationship between the correlation between propagation path responses and the cross-polarization power ratio. Based on this experiment, we have clarified the relationship between the correlation between propagation path responses and the cross-polarization power ratio. In addition, in the transmission device and the reception device of the polarization MIMO-OFDM transmission system using orthogonal polarization according to the present invention, a means for adjusting the cross polarization characteristics on the transmission side or the reception side is provided, and the propagation path While suppressing an increase in the correlation between them, the decrease in reception diversity is minimized, and transmission degradation of MIMO-OFDM transmission in a line-of-sight environment is prevented.

  In a general MIMO-OFDM transmission system, it is known that the MIMO transmission characteristics are significantly degraded when the correlation between channel responses increases. FIG. 2 shows the result of the error rate after inner code (after soft decision Viterbi decoding) with respect to the correlation value of the propagation path measured by conducting a transmission-system / receive-system MIMO-OFDM transmission experiment in an outdoor line-of-sight environment. An equation for obtaining a correlation value between the propagation path responses can be calculated using, for example, Equation (1).

Here, k is the number of the receiving antenna, i and j are the numbers of the transmitting antenna, and m is the pilot carrier number. From FIG. 2, as the correlation value of the propagation path increases, the point at which the error rate deteriorates increases, and especially when the correlation value exceeds 0.8, the error rate 2 is the limit value of the correction capability of outer code error correction. An error of 0.times.10.sup.- ⁴ or more is abruptly generated. From FIG. 2, it can be seen that the transmission characteristics of MIMO-OFDM transmission may suddenly deteriorate as the correlation value of each propagation path increases.

Therefore, when the correlation of each propagation path such as a line-of-sight environment is high, as shown in FIG. 3, the transmitter and receiver of the polarization MIMO-OFDM transmission system using different polarizations (orthogonal polarization in FIG. 3) It is widely known that the correlation between propagation path responses can be suppressed by configuring 20. FIG. 3 shows a case where a vertical polarization antenna is assigned to the transmission antenna Tx ₁ and the reception antenna Rx ₁ and a horizontal polarization antenna is assigned to the transmission antenna Tx ₂ and the reception antenna Rx ₂ .

At this time, the OFDM signal transmitted from the vertically polarized transmitting antenna Tx ₁ is received without being attenuated by the vertically polarized receiving antenna Rx ₁ and is transmitted from the horizontally polarized transmitting antenna Tx _2. Is received by a vertically polarized receiving antenna Rx ₁ with a large attenuation. The amount of attenuation increases as the orthogonality of the polarization of the OFDM signal received by the receiving antenna is maintained, and is particularly noticeable in a line-of-sight environment with little reflection. On the other hand, the OFDM signal transmitted from the horizontally polarized transmitting antenna Tx ₂ is received with a large attenuation at the vertically polarized receiving antenna Rx ₁ , and the OFDM signal is attenuated at the receiving antenna at the horizontally polarized receiving antenna Rx _2. Received without. This makes it possible to keep the correlation of each channel response low, and facilitates signal separation by MIMO demodulation of OFDM signals transmitted on the same frequency in a horizontally polarized wave and vertically polarized wave transmitting antenna. Thus, the MIMO-OFDM transmission characteristics are improved.

  However, in a line-of-sight environment with few reflected waves, the orthogonality of horizontal and vertical polarization is maintained even at the receiving antenna. For example, OFDM signals transmitted with vertical polarization are almost received by the receiving antenna with horizontal polarization. As a result, an OFDM signal is received by one receiving antenna, and the reception diversity effect originally obtained by two receiving antennas is halved, leading to deterioration of transmission characteristics.

Therefore, the cross-polarization power ratio delta _p4 in MIMO-OFDM transmission transmits two systems and receive 4 lines were calculated from the power ratio of the channel response between the transmitting and receiving antennas (Equation (2)), the cross polarization power ratio Based on the measured data of the experiment, how the correlation distribution of each channel response changes depending on the value of was obtained by computer simulation. FIG. 4 is a diagram illustrating a correlation relationship of each propagation path response according to the value of the cross polarization power ratio. In Expression (2), k represents a reception antenna number and a propagation path response, and h _ij represents a propagation path response between the transmission antenna j and the reception antenna i.

A large value of the cross polarization power ratio _Δp4 indicates that the orthogonality between the OFDM signals received from the polarization antennas Rx ₁ and Rx ₂ received by the receiving device 20 is large. The magnitude of the cross polarization power ratio indicating the degree of orthogonality greatly affects the correlation of the propagation path and the transmission characteristics. FIG. 4 shows a case where the cross polarization power ratio is changed from the result of propagation path response measured by performing a transmission experiment in an outdoor line-of-sight environment using a MIMO-OFDM transmission system of two transmission systems and four reception systems. The correlation of the propagation path response is obtained from equation (1). In the measurement of FIG. 4, the transmitting antenna and the receiving antenna are all vertically polarized.

  From FIG. 4, it can be seen that as the cross polarization power ratio increases, the correlation value of each propagation path decreases overall. In addition, in FIG. 2, when considering the correlation value 0.8 of the propagation path response when the MIMO-OFDM transmission characteristics are rapidly deteriorated, all propagation paths can be obtained if the cross polarization power ratio is kept at 4 dB or more. It can be seen that the correlation value of the response can be 0.8 or less.

  Further, FIG. 5 shows a change in error rate due to a change in the cross polarization power ratio. It can be seen that when the cross polarization power ratio is between 0 dB and 6 dB, the error rate characteristics improve as the cross polarization power ratio increases. This is thought to be because the correlation of each channel response is reduced due to an increase in the cross polarization power ratio, and the signal separation performance of MIMO demodulation is improved. On the other hand, when the cross polarization power ratio exceeds 8 dB, the error rate characteristics gradually deteriorate. This is because the reception diversity effect due to the decrease in received power of different polarizations at the receiving antenna as the cross-polarization power ratio increases as compared to the improvement in signal separation performance due to the small correlation of each channel response. This is because the effect of the decrease became larger. From this, it was found that by suppressing the cross polarization power ratio in the receiving antenna to about 4 dB to 8 dB, it is possible to prevent a significant deterioration in transmission characteristics of MIMO-OFDM transmission using orthogonal polarization.

  Hereinafter, based on the above experimental results, while efficiently suppressing the correlation of each propagation path, suppressing the reduction of the reception diversity effect generated by using the polarization, to improve the MIMO-OFDM transmission characteristics, Embodiments of the transmission apparatus and the reception apparatus of the polarization MIMO-OFDM transmission system according to the present invention will be described.

FIG. 6 is a block diagram illustrating a transmission apparatus and a reception apparatus of the polarization MIMO-OFDM transmission system according to the first embodiment of the present invention. The polarization MIMO-OFDM transmission system of this embodiment includes a transmission device 10 and a reception device 20. The transmission apparatus 10 of the present embodiment is applicable to a “millimeter wave mobile camera”, and is configured to transmit video information to the reception apparatus 20 by MIMO-OFDM. The receiving device 20 can transmit a signal capable of controlling the “millimeter wave mobile camera”, and can transmit a return signal such as a camera control signal or a return video to the transmitting device 10. The polarization MIMO-OFDM transmission system of the present embodiment is a system for transmitting a signal from the transmission apparatus 10 to the reception apparatus 20 (hereinafter referred to as “main line system”), and includes two transmission antennas Tx ₁ , Tx ₂ and It is assumed that the receiving antennas Rx ₁ and Rx ₂ are provided, and that a transmission function of a system for transmitting a signal from the receiving device 20 to the transmitting device 10 (hereinafter referred to as “sending system”) is provided. The transmission function used for the return system is described as using the dedicated antennas 102 and 202, but may be wired.

The transmission apparatus 10 receives and encodes video information, generates a complex signal having the same number as the number of transmission antennas, and a signal transmitted from the transmission antenna Tx ₁ among the complex signals generated by the MIMO encoding unit 110. OFDM signal generation section 120 that generates a first system OFDM signal to be transmitted, and OFDM signal generation that generates a second system OFDM signal that is transmitted by transmission antenna Tx ₂ among the complex signals generated by MIMO encoding section 110 Unit 130, a polarization control unit 140 for controlling the polarization of the OFDM signal of the first system and transmitting a radio wave by the transmission antenna Tx ₁ , and a transmission antenna Tx ₂ for controlling the polarization of the OFDM signal of the second system Cross polarization power ratio information (Δp2_Rx ₁ , Δp2) from the polarization control unit 150 that transmits radio waves and the receiver 20 via the antenna 102. _Rx ₂ ), a return reception unit 170, an XPD adjustment unit 160 that adjusts the cross polarization discrimination (XPD) of the transmission antenna Tx ₁ and the transmission antenna Tx ₂ based on the received cross polarization power ratio information, Is provided.

This transmission apparatus 10 can be configured to generate two systems of OFDM signals and to have a horizontally polarized wave transmission antenna and a vertically polarized wave transmission antenna assigned to each system. For example, the transmission antenna Tx ₁ is equipped with a horizontal polarization transmission antenna and a vertical polarization transmission antenna, and the transmission antenna Tx ₂ is equipped with a horizontal polarization transmission antenna and a vertical polarization transmission antenna.
However, although the present embodiment has been described by taking a MIMO-OFDM transmission apparatus equipped with two transmission antennas as an example, the present embodiment can be realized even when the number of transmission antennas is increased. For example, the number of transmission antennas can be increased by providing a transmission antenna having a 45-degree polarization relationship separately from a horizontal polarization transmission antenna and a vertical polarization transmission antenna having a 90-degree polarization relationship.

  The MIMO encoding unit 110 performs encoding such as energy spreading, error correction encoding, and interleaving on the video information captured on the transmission apparatus 10 side, and generates a complex signal separated into two in this example.

  The OFDM signal generation sections 120 and 130 generate OFDM signals by performing processes such as carrier modulation, frame configuration, IFFT processing, and GI signal addition on the signals that have been encoded separately in two. .

Based on the cross polarization power ratio (Δ _{p2_Rx1} and Δ _{p2_Rx2} ) calculated by the receiving device 20 in the send back receiving unit 170, the XPD adjustment unit 160 uses the optimal cross polarization power ratio on the receiving side for the number of transmission systems (this In the example, the cross polarization discrimination (XPD) between the transmission antennas capable of receiving OFDM signals of two systems) is calculated, and each cross transmission discrimination (XPD) is satisfied for each transmission system. The power distribution ratio of the OFDM signal to the horizontal component / vertical component in the transmission antenna is determined and output to the polarization controllers 140 and 150.

The polarization control units 140 and 150 adjust the cross polarization identification of the OFDM signal output from the vertical polarization / horizontal polarization transmission antenna of each system based on the power distribution ratio output from the XPD calculation unit 160. The OFDM signals are transmitted from the transmission antennas Tx ₁ and Tx _{2 of} each system.

The receiving apparatus 20 receives and demodulates the two systems of OFDM signals via _two receiving antennas Rx ₁ and Rx ₂ (for example, one is a horizontally polarized antenna and the other is a vertically polarized antenna). The OFDM signal demodulation that estimates the propagation path response from the pilot signal obtained via the receiving antenna of each polarization and outputs information (h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) of the estimated propagation path response, respectively. Information of the channel responses estimated from the data obtained from the units 210 and 220 and the OFDM signals demodulating units 210 and 220 and the pilot signals obtained via the reception antennas of the respective polarizations (h ₁₁ , h ₂₁ , h ₁₂ , enter the h _22), a MIMO decoder 230 which decodes the video information subjected to error correction decoding processing after performing MIMO demodulation, OFDM signal demodulation section 21 , An XPR calculation unit 240 for calculating the cross-polarization power ratio _(Δ p2_Rx1 and _Δ p2_Rx2) for each receiving system from the information of the channel response obtained from _{220 (h 11, h 21,} h 12, h 22), calculated The cross-polarization power ratio information is transmitted to the transmission device 10 via the antenna 202.

In the receiving device 20, the two systems of OFDM signals transmitted from the transmitting device 10 are received by the respective receiving antennas Rx ₁ and Rx ₂ in a form of interference on the same frequency. These two OFDM signals are respectively input to OFDM signal demodulation sections 210 and 220 and subjected to processing such as symbol synchronization by guard correlation, GI signal removal, FFT processing, frame separation, and the like. The propagation path responses (h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) between the transmitting and receiving antennas are obtained by the method shown in FIG. The MIMO decoding unit 230 performs a MIMO decoding process using this data signal and a propagation path response between each transmission / reception antenna, and restores the original video signal transmitted from the transmission apparatus 10.

The XPR operation unit 240 determines propagation paths between different polarizations based on propagation path responses (h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) between the transmission and reception antennas obtained by the OFDM signal demodulation units 210 and 220 used for MIMO decoding. The power ratio of the response is calculated as the cross polarization power ratio ( _{Δp2_Rx1} and _{Δp2_Rx2} ) for each reception system. This arithmetic expression is expressed by, for example, Expression (3) and Expression (4).

As the absolute values of the cross polarization power ratio values _{Δp2_Rx1} and _{Δp2_Rx2} are larger, the orthogonality between the OFDM signals received from the respective polarization antennas Rx ₁ and Rx ₂ received by the receiving device 20 is larger. Show. Therefore, as described above, the absolute values of _{Δp2_Rx1} and _{Δp2_Rx2} indicating the degree of orthogonality greatly affect the correlation and transmission characteristics of the channel response.

FIG. 7 is a diagram illustrating a configuration example of the XPR calculation unit 240 in the reception device 20. There are as many estimated channel responses as the number of carriers of the OFDM signal. The XPR calculation unit 2401 shown in FIG. 7 performs the calculation of Expression (2) for the propagation path response of each carrier. Thereafter, the data processing unit 2402 calculates and outputs an average or a median value for the cross polarization power ratios ( _{Δp2_Rx1} and _{Δp2_Rx2} ) for the number of carriers obtained by the XPR calculation unit 2401. The data processing unit 2402 may be configured to output all of the plurality of cross polarization power ratios obtained by the XPR calculation unit 2401 without performing processing such as median or averaging.

  The XPR calculation unit 240 sends the cross polarization power ratio obtained from the estimated propagation path response to the sending back transmission unit 250, and the sending back transmission unit 250 causes the sending apparatus 10 to send it together with a sending back signal such as a camera control signal and a sending back video. . For transmission of the return signal, frequency division multiplexing transmission or MIMO multiplexing transmission technology using a frequency different from the main transmission MIMO-OFDM transmission can be used.

FIG. 8 is a diagram illustrating a configuration example of the XPD adjustment unit 160 in the transmission device 10. The XPD adjustment unit 160 _obtains the absolute value of the cross polarization power ratio (Δ _{p2_Rx1} and Δ _{p2_Rx2} ) measured on the receiving device 20 side obtained from the _return reception unit 250 and the cross polarization recorded in the reference XPR recording unit 1601. A subtractor 1602 that calculates a difference value from the reference value of the power ratio, respectively, and if the obtained difference value is positive, the currently set XPD value is lowered, and if it is negative, the currently set XPD value An _inter- polarization power ratio calculation unit 1603 that calculates the power ratio ( _{Δp_V} , _{Δp_H} ) between horizontal polarizations and between vertical polarizations. Although the reference value of the cross polarization power ratio recorded in the reference XPR recording unit 1601 depends on the propagation environment in which the actual MIMO-OFDM transmission is performed, as described above, it is about 4 dB to 8 dB in the outdoor line-of-sight environment. It is preferable to take a value.

FIG. 9 is an explanatory diagram of a method of adjusting the cross polarization discrimination degree in the polarization control units 140 and 150 in the transmission apparatus 10. In Figure 9, it shows an example in which adjustment and outputs the power ratio of the horizontal polarization and vertical polarization of the OFDM signals of the respective systems as delta _{p_v} and delta _{P_H.} In this case, an OFDM signal is output from each vertically polarized transmission antenna in the transmission system 1 and the transmission system 2 so that the power ratio between the OFDM signal in the transmission system 1 and the OFDM signal in the transmission system 2 is increased by _{Δp_V.} . On the other hand, from the horizontally polarized wave transmission antennas in the transmission system 1 and the transmission system 2, an OFDM signal is output so that the power ratio between the OFDM signal in the transmission system 1 and the OFDM signal in the transmission system 2 is reduced by _{Δp_H} . At this time, the same OFDM signals that differ only in the power ratio are transmitted from the transmission antennas of different polarizations in the same transmission system.

  Therefore, according to the transmission apparatus and the reception apparatus of the polarization MIMO-OFDM transmission system of the first embodiment according to the present invention, the correlation of each channel response is suppressed even in the polarization MIMO-OFDM transmission using orthogonal polarization. In addition, it is possible to limit the reduction of the reception diversity effect, and it is possible to improve the transmission performance as compared with the conventional MIMO-OFDM transmission scheme using orthogonal polarization.

  Further, in the first embodiment, the case of two receiving antennas has been described. However, in MIMO-OFDM transmission using more receiving antennas, the ratio of each channel response for each polarization obtained by the OFDM demodulating unit is set. This can be realized by calculating the value of the cross polarization power ratio. For example, when four receiving antennas # 1 to # 4 are used, the vertical polarization is assigned to the receiving antennas # 1 and # 3, and the horizontal polarization is assigned to the receiving antennas # 2 and # 4. An equation for calculating the wave power ratio can be expressed by equation (2).

  Next, a transmitting apparatus and a receiving apparatus of the polarization MIMO-OFDM transmission system according to the second embodiment of the present invention will be described.

(Example 2)
In the first embodiment described above, the configuration example has been described in which one transmission antenna of horizontal polarization and vertical polarization is arranged in each transmission system on the transmission apparatus 10 side. In the second embodiment, one transmission antenna having a different polarization is arranged in each transmission system of the transmission device 10 and the inclination of the polarization antenna is adjusted in each transmission system, so that the optimal intersection on the reception device 20 side is achieved. A configuration example for adjusting to the cross polarization discrimination degree, which becomes the polarization power ratio, will be described. Therefore, the second embodiment is the same as the configuration illustrated in FIGS. 6 to 8 except for the configuration of the transmission antenna and the operation of the polarization control units 140 and 150.

That is, the transmission apparatus 10 of the present embodiment is configured to include a horizontally polarized wave transmission antenna or a vertically polarized wave transmission antenna for each system. For example, two systems of OFDM signals are generated, and the transmission antenna Tx ₁ configure the horizontally polarized transmitting antenna, constituting the vertically polarized transmit antennas at the transmitting antenna Tx _2.

  As an example of the transmission antenna of the second embodiment, for example, there is a horn antenna having a strong antenna directivity with a longer horn length. The configuration and operation on the receiving device 20 side are the same as in the first embodiment.

On the transmitting apparatus 10 side, as in the first embodiment, the horizontal component between the transmitting antennas in the XPD adjustment unit 160 is calculated based on the cross polarization power ratio values ( _{Δp2_Rx1} and _{Δp2_Rx2} ) calculated on the receiving apparatus 20 side. The power ratio of the vertical component ( _{Δp_V} and _{Δp_H} ) is calculated. However, in the second embodiment, the polarization controllers 140 and 150 adjust the angle θ of the horn antenna that is each transmission antenna based on this power ratio. FIG. 10 shows how the angle θ is adjusted. FIG. 10A shows a state before adjustment, and FIG. 10B shows a state after adjustment.

  In FIG. 10, in order to reduce the cross polarization discrimination of the transmitting antenna on the transmitting apparatus side, the vertical component is decreased and the horizontal component is increased by rotating the vertically polarized transmitting antenna that is oriented in the vertical component direction. ing. This is because the polarization control units 140 and 150 record the directivity characteristics of the vertical polarization transmission antenna in advance, so that the vertical component power ratio and horizontal component power ratio obtained by the XPD adjustment unit 160 are satisfied. Adjust the inclination of the two transmission antennas. Thereby, it becomes possible to adjust the cross polarization discrimination degree of the OFDM signal output from the transmission apparatus 10 side. Adjust the tilt of the transmission antenna of each system by rotating the vertical polarization transmission antenna, rotating the horizontal polarization transmission antenna, or rotating both the vertical polarization transmission antenna and the horizontal polarization transmission antenna. can do.

  Therefore, also in the polarization MIMO-OFDM transmission system transmitter and receiver according to the second embodiment of the present invention, the correlation of each channel response in polarization MIMO-OFDM transmission using orthogonal polarization is suppressed and received. The reduction of the diversity effect can be limited, and the transmission performance can be improved as compared with the conventional MIMO-OFDM transmission system using orthogonal polarization.

  In the second embodiment, MIMO-OFDM transmission using two transmission antennas has been described as an example. However, in MIMO-OFDM transmission in which three or more transmission antennas are used to transmit different signals from each system. Technology can be applied. For example, when three transmission antennas are used, the transmission antenna 1 tilted to a position (vertical direction) where the directivity peak of the antenna pattern of the transmission antenna is perpendicular to the ground, and a horizontal position (horizontal direction) In addition to the transmission antenna 2 inclined to the angle, the transmission antenna 3 inclined by 45 ° in the horizontal direction, for example, is arranged from the vertical direction which is intermediate between the vertical direction and the horizontal direction. At this time, by changing the positional relationship (antenna tilt) of the three transmission antennas, it becomes possible to control the correlation value of each propagation path propagating from the three antennas to each reception antenna. It is possible to improve transmission characteristics even in a line-of-sight environment while minimizing the decrease in effect.

  Next, a transmitting apparatus and a receiving apparatus of the polarization MIMO-OFDM transmission system according to the third embodiment of the present invention will be described.

(Example 3)
In the first and second embodiments, on the transmission device 10 side, the vertical component and horizontal component of the transmission antenna obtained by the XPD adjustment unit 160 based on the cross polarization power ratio ( _{Δp2_Rx1} and _{Δp2_Rx2} ) obtained on the reception device 20 side. The cross polarization discrimination was adjusted based on the component polarization ratios ( _{Δp_V} and _{Δp_H} ). In the third embodiment, the cross-polarization power ratio is obtained by adjusting the polarization by changing the direction of the reception antenna on the receiving device 20 side based on the obtained cross-polarization power ratio ( _{Δp2_Rx1} and _{Δp2_Rx2} ). This is a mode of changing to a desired value.

FIG. 11: is a block diagram which shows the transmitter and receiver of the polarization MIMO-OFDM transmission system of Example 3 which concerns on this invention. The transmission apparatus 10 of the present embodiment inputs and encodes video information, generates a complex signal having the same number as the number of transmission antennas, and a transmission antenna among the complex signals generated by the MIMO encoding unit 110. An OFDM signal generator 120 that generates a first-system OFDM signal that transmits a signal using Tx ₁ , and a second-system OFDM signal that transmits a signal using a transmission antenna Tx ₂ among complex signals generated by the MIMO encoder 110. And an OFDM signal generator 130. The operations of the MIMO encoder 110 and the OFDM signal generators 120 and 130 are the same as those in the first embodiment.

The receiving apparatus 20 of the present embodiment receives and demodulates the two systems of OFDM signals via the two receiving antennas Rx ₁ and Rx ₂ (each using a horn antenna), and receives each polarization receiving antenna. OFDM signal demodulating sections 210 and 220 for estimating the propagation path response from the signal obtained through the above and outputting information (h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) of the estimated propagation path response, respectively, and the OFDM signal Information on propagation path responses (h ₁₁ , h ₂₁ , h ₁₂ , h ₂₂ ) estimated from the data obtained from the demodulation units 210 and 220 and the signals obtained via the reception antennas of the respective polarizations are input, and MIMO is input. A MIMO decoding unit 230 that decodes video information by performing diversity combining after separation, and a channel response obtained from OFDM signal demodulation units 210 and 220 It is the same as the first embodiment in including a XPR calculation unit 240 for calculating the cross-polarization power ratio _(Δ p2_Rx1 and _Δ p2_Rx2) for each receiving system from the information _{(h 11, h 21, h} 12, h 22) . The receiving apparatus 20 of the present embodiment further calculates a difference value from the optimum cross polarization power ratio of about 4 dB to 8 dB prerecorded in the reference XPR recording unit 280 based on the calculated cross polarization power ratio information. The vertical polarization receiving antenna is rotated according to the difference value, the horizontal polarization receiving antenna is rotated, or both the vertical polarization receiving antenna and the horizontal polarization receiving antenna are rotated, The difference is that polarization control units 260 and 270 that adjust the directivity directions (inclinations of the Horner antennas) of the receiving antennas Rx ₁ and Rx ₂ are provided.

A horn antenna can be used for each of the receiving antennas Rx ₁ and Rx ₂ of the receiving device 20. The OFDM signal received by the receiving device 20 is decoded into the original video information in the OFDM signal demodulating units 210 and 220 and the MIMO decoding unit 230 as in the first embodiment. From the propagation path responses estimated by the OFDM signal demodulation units 210 and 220 used for this decoding, the XPR calculation unit 240 determines the cross polarization power ratio ( _{Δp2_Rx1} and _{Δp2_Rx2} ) in each reception system as in the first embodiment. To calculate.

The subtraction units 290-1 and 290-2 are cross polarization power ratios Δ _{p2_Rx1} and Δ _{p2_Rx2} calculated by the XPR calculation unit 240 and an optimum cross polarization power of about 4 dB to 8 dB recorded in the reference XPR recording unit 280. A difference value with respect to the ratio is obtained, and these difference values are supplied to the polarization controllers 260 and 270, respectively.

Polarization control unit 260 adjusts the directivity of the direction of reception based on a signal from the subtraction unit 290-1 antennas Rx ₁ (the slope of Ho Na antennas), polarization control unit 270, the subtraction unit 290-2 The direction of the directivity of the receiving antenna Rx ₂ (the inclination of the Horner antenna) is adjusted based on the signal from. Adjustment of the directivity direction (horner antenna inclination) of each of the _two receiving antennas Rx ₁ and Rx ₂ is similar to that in the second embodiment, when the obtained difference value is negative, the orthogonality of the polarization is changed. In order to increase, when the obtained difference value is positive, the inclination of the horn antenna is adjusted so as to reduce the orthogonality of the polarization. In addition, the inclination of the horn antenna is greatly changed as the absolute value of the difference value increases.

FIG. 12 shows an example of a receiving antenna directivity adjustment method by the polarization control units 260 and 270. FIG. 12A shows a state before adjustment, and FIG. 12B shows a state after adjustment. In the polarization control units 260 and 270, the reception antennas Rx ₁ and Rx are set so that the inter-polarization power ratio according to the difference value calculated based on the directivity characteristic of each reception antenna recorded in the reference XPR recording unit 280. ₂ respectively, the inclinations θ ₁ and θ ₂ are adjusted. As a result, even when the MIMO-OFDM transmission system is not equipped with a transmission unit for the return system, the optimum cross polarization power ratio can be obtained only by adjusting the angles of the receiving antennas Rx ₁ and Rx ₂ on the receiving device 20 side. Can receive an OFDM signal. Further, in the present embodiment, the case where two receiving antennas are equipped has been described as an example. However, in a receiving apparatus equipped with three or more receiving antennas, the cross polarization power ratio is obtained by each receiving antenna, The present technology can be applied by controlling the polarization plane of the receiving antenna.

  Therefore, also in the polarization MIMO-OFDM transmission system transmitter and receiver according to the third embodiment of the present invention, the correlation of each channel response in polarization MIMO-OFDM transmission using orthogonal polarization is suppressed and received. The reduction of the diversity effect can be limited, and the transmission performance can be improved as compared with the conventional MIMO-OFDM transmission system using orthogonal polarization.

  Next, a transmitting apparatus and a receiving apparatus of the polarization MIMO-OFDM transmission system according to the fourth embodiment of the present invention will be described.

Example 4
FIG. 13 is a block diagram of a transmission device and a reception device of the polarization MIMO-OFDM transmission system according to the fourth embodiment of the present invention. The polarization MIMO-OFDM transmission system according to the fourth embodiment is an example in which the transmission device 10 according to the first embodiment and the reception device 20 according to the third embodiment are combined. The operations of the transmission device 10 and the reception device 20 are the same as those of the first and third embodiments. By adjusting both the transmission side and the reception side, the propagation path in the polarization MIMO-OFDM transmission system with finer accuracy. The reception diversity effect can be adjusted according to the characteristics.

  Next, a transmitting apparatus and a receiving apparatus of the polarization MIMO-OFDM transmission system according to the fifth embodiment of the present invention will be described.

(Example 5)
According to the first to fourth embodiments, in MIMO-OFDM transmission using polarization in an outdoor line-of-sight environment with few reflected waves, according to the polarization power ratio of the transmitting antenna on the transmitting device 10 side or the receiving antenna on the receiving device 20 side. By transmitting or receiving an OFDM signal, the correlation characteristics of the propagation path between the transmitting and receiving antennas are suppressed while minimizing the decrease in reception diversity, and there are many reflected waves that are ideal for MIMO-OFDM transmission. It has been explained that transmission with minimized degradation of transmission characteristics is possible as compared with MIMO-OFDM transmission in the outside environment.

  FIG. 14 is a diagram illustrating another configuration example of the XPR calculating unit in the receiving apparatus of the polarization MIMO-OFDM transmission system in the first to fourth embodiments as the fifth embodiment. The XPR calculation unit 240 of this embodiment includes a propagation path correlation calculation unit 2410, a reference correlation value recording unit 2411, a subtraction unit 2412, an XPR minimum value output unit 2413, and an XPR calculation unit 2414.

  The XPR calculation unit 240 according to the present embodiment uses the propagation path correlation calculation unit 2410 to calculate the propagation path response shown in Equation (1) and calculate the correlation value, and the calculated correlation value and the reference correlation value recording unit 2411. The subtraction unit 2412 obtains the difference from the reference correlation value recorded in the above, and when the correlation value is higher than the reference correlation value, the cross-polarization power ratio is obtained by the XPR calculation unit 2414 as in the first to fourth embodiments. When the correlation value obtained by the propagation path correlation calculation unit 2410 is lower than the reference correlation value, a switching mechanism for switching from the XPR calculation unit 2414 to the XPR minimum value output unit 2413 is provided. The XPR minimum value output unit 2413 outputs a minimum value of XPR (an absolute value of a sufficiently small cross polarization power ratio set in advance). This is because if the correlation value of each propagation path can be kept below a certain level, the transmission characteristics of MIMO-OFDM transmission in the line-of-sight environment can be improved. Therefore, if the correlation value of each propagation path is below a certain value. In order to prevent the XPR value from becoming larger than necessary. In particular, in a non-line-of-sight environment or the like, the correlation value of each propagation path is originally low, so that the influence of a decrease in received power due to the use of orthogonal polarization becomes large. Therefore, when the correlation value of each propagation path is low, the polarization plane of the antenna is adjusted so that the XPR value becomes the minimum value. For example, the XPR value can be adjusted to a minimum value by a method in which all antennas are transmitted in accordance with the same vertical polarization plane.

  Therefore, when the correlation value obtained by the propagation path correlation calculation unit 2410 is lower than the reference correlation value, the XPR calculation unit 240 of the present embodiment outputs a value of the cross polarization power ratio whose absolute value is sufficiently small. By doing so, it is possible to intentionally adjust the orthogonality to be low, and to improve the transmission characteristics of MIMO-OFDM transmission in a non-line-of-sight environment with many reflected waves with low propagation path correlation characteristics. In this case, in the case of the polarization MIMO-OFDM transmission system of the first embodiment, adjustment is performed so that the OFDM signal is output with equal power from the vertical polarization and horizontal polarization antennas provided in each transmission system. In the case of the polarization MIMO-OFDM transmission systems of Examples 2 to 4, the angle of the polarization antenna is adjusted so that the horizontal component and the vertical component are the same.

  According to the present embodiment, the MIMO-OFDM transmission characteristics using polarized waves are generally deteriorated due to a decrease in the reception diversity effect due to the polarized waves in the non-line-of-sight environment where there are many reflected waves. It is possible to minimize the decrease in the reception diversity effect due to the use of polarization, and to suppress the degradation of the MIMO-OFDM transmission characteristics.

  According to the present invention, it is possible to perform polarization adjustment in consideration of the reception diversity effect, which is useful for the use of a MIMO-OFDM transmission system using polarization.

DESCRIPTION OF SYMBOLS 10 Transmitting device 20 Receiving device 101-1 and 101-2 Transmitting antenna 102 Antenna
DESCRIPTION OF SYMBOLS 110 MIMO encoding part 120 OFDM signal generation part 130 OFDM signal generation part 140 Polarization control part 150 Polarization control part 160 XPD adjustment part 170 Send back receiving part 201-1, 201-2 Reception antenna 202 Antenna 210, 220 OFDM signal demodulation Unit 230 MIMO decoding unit 240 XPR operation unit 250 send back transmission unit 260,270 polarization control unit 280 reference XPR recording unit 290-1,290-2 subtraction unit 2401 XPR calculation unit 2402 data processing unit 1601 reference XPR recording unit 1602 subtraction unit 1603 Inter-polarization power ratio calculation unit 2410 propagation path correlation calculation unit 2411 reference correlation value recording unit 2412 subtraction unit 2413 XPR minimum value output unit 2414 XPR calculation unit

Claims (7)

A polarization MIMO-OFDM transmission system transmission device that transmits video information using a plurality of transmission antennas,
A MIMO encoding unit that inputs and encodes video information and generates a complex signal having the same number as the number of transmission antennas;
An OFDM signal generation unit for each system that generates a plurality of OFDM signals for the plurality of transmission antennas among the complex signals generated by the MIMO encoding unit;
A polarization control unit for each system for controlling the polarization of the OFDM signals of the plurality of systems and transmitting radio waves;
A send-back receiving unit that receives information on the cross polarization power ratio from the receiving side;
An XPD adjustment unit that adjusts the degree of cross-polarization discrimination in the plurality of transmission antennas based on the received cross-polarization power ratio information;
A transmission device comprising: The transmitting antenna is configured to include a horizontally polarized wave transmitting antenna and a vertically polarized wave transmitting antenna allocated to each system one by one,
The XPD adjustment unit is capable of receiving OFDM signals corresponding to the number of transmission systems at an optimum cross polarization power ratio on the reception side based on information on the cross polarization power ratio calculated on the reception side in the return reception unit. Calculate the cross polarization discrimination between the antennas, determine the power distribution ratio of the OFDM signal to the horizontal and vertical components in each transmission antenna so as to satisfy the cross polarization discrimination for each transmission system, The transmission apparatus according to claim 1, wherein an OFDM signal whose power is adjusted is assigned to the polarization control unit. The transmission antenna is configured to include a horizontally polarized wave transmitting antenna or a vertically polarized wave transmitting antenna for each system,
The XPD adjustment unit is capable of receiving OFDM signals corresponding to the number of transmission systems at an optimum cross polarization power ratio on the reception side based on information on the cross polarization power ratio calculated on the reception side in the return reception unit. Calculate the cross polarization discrimination between the antennas, determine the power distribution ratio of the OFDM signal to the horizontal and vertical components in each transmission antenna so as to satisfy the cross polarization discrimination for each transmission system, For the polarization control unit, rotate the vertical polarization transmission antenna, rotate the horizontal polarization transmission antenna, or rotate both the vertical polarization transmission antenna and the horizontal polarization transmission antenna, The transmission apparatus according to claim 1, wherein an inclination of a transmission antenna of each system is adjusted. A polarization MIMO-OFDM transmission system receiver that receives video information using a plurality of receiving antennas,
Receives and demodulates multiple systems of OFDM signals from the transmitting side via the multiple receiving antennas including horizontal and vertical polarization antennas, and estimates the channel response from the signals obtained via the receiving antennas An OFDM signal demodulator for each receiving system that outputs information of the estimated channel response,
Inputs each OFDM signal data obtained from the OFDM signal demodulator and information on the propagation path response estimated from the signal obtained via the receiving antenna, performs MIMO separation, decodes video information by performing diversity combining A MIMO decoding unit;
An XPR calculation unit for calculating the cross polarization power ratio for each reception system from the information of the propagation path response obtained from the OFDM signal demodulation unit;
A receiving apparatus comprising: Further comprising a transmission unit for transmitting the calculated cross polarization power ratio information to the transmission side,
5. The receiving apparatus according to claim 4, wherein the cross polarization discrimination degree of the plurality of transmission antennas is adjusted based on information on the cross polarization power ratio received on the transmission side. The receiving antenna is configured to have a horizontally polarized wave receiving antenna or a vertically polarized wave receiving antenna for each system,
Based on the information on the calculated cross polarization power ratio, a difference value with the optimum cross polarization power ratio recorded in advance in a predetermined reference XPR recording unit is obtained, and the vertical polarization receiving antenna is determined based on the difference value. A polarization control unit that adjusts the inclination of the reception antenna for each system by rotating, rotating the horizontal polarization reception antenna, or rotating both the vertical polarization reception antenna and the horizontal polarization reception antenna. The receiving apparatus according to claim 4, further comprising: The XPR operation unit
When calculating the channel response and calculating the correlation value, the difference between the calculated correlation value and the reference correlation value recorded in the predetermined reference correlation value recording unit is obtained, and if it is higher than the reference correlation value, 7. A switching mechanism that obtains a cross polarization power ratio while switching to output a predetermined minimum XPR value when the obtained correlation value is lower than a reference correlation value is provided. The receiving device according to any one of the above.