JP6694321B2 - Reception quality measuring device and program - Google Patents

Description

  The present invention relates to a reception quality measuring device and program for measuring reception quality at a specific point.

  With the aim of transmitting 8K Super Hi-Vision, next-generation terrestrial broadcasting is being studied in addition to satellite broadcasting. Among them, the polarization MIMO technology that doubles the transmission capacity by simultaneously using the horizontal polarization and the vertical polarization is drawing attention.

  In such a polarization MIMO technique, a method of separating signals with high accuracy is known, for example, by using a carrier power to noise power ratio (C / N: Carrier to Noise Ratio) as an index for determining signal quality. (For example, see Patent Document 1).

  Further, in terrestrial digital broadcasting using polarization MIMO technology, a reception quality measuring device for measuring reception quality at a specific point by using MER or carrier power to noise power ratio (C / N: Carrier to Noise Ratio) It has been known.

  This reception quality measuring device measures the MER or the reception C / N at a specific point and receives the MER or the reception C / N (hereinafter, required MER, required C / N) necessary for receiving a signal from the transmission side without error. The difference up to () is measured and presented as a margin. The larger the margin value, the better the reception quality.

  In terrestrial digital broadcasting, the required C / N fluctuation can be reduced by the technology of transmitting and receiving using only one of the horizontal polarization and the vertical polarization, and the technology of compensating the distortion of the frequency characteristic due to reflection or shielding. Can be made smaller. By this means, it is possible to observe the margin of reception quality at that point.

  However, in the polarization MIMO technique, the reception side receives two polarizations having different reception characteristics, demodulates them, and performs signal separation for eliminating interference between the polarizations. Therefore, even in the same polarization MIMO transmission system, the required C / N may vary greatly depending on the propagation environment.

  FIG. 7 is a diagram showing how the reception quality varies depending on the propagation environment. FIG. 7A shows the reception quality when the frequency characteristic (transmission path characteristic) in the band is constant and the propagation environment is good. In FIG. 7B, the frequency characteristic is not constant and distorted. , Shows the reception quality when the propagation environment is bad.

  As shown in FIG. 7A, when the propagation environment is good, the actual required C / N at that point does not deviate from the original required C / N of the polarization MIMO transmission system. Therefore, the apparent allowance is equal to the original allowance.

  On the other hand, as shown in FIG. 7B, when the propagation environment is bad, the actual required C / N at that point deviates from the original required C / N of the polarization MIMO transmission system. Therefore, the apparent allowance is significantly different from the actual allowance. When the propagation environment is extremely bad, the actual required C / N exceeds the received C / N, and there may occur a situation in which reception is impossible despite the apparent allowance.

  In the polarization MIMO transmission system, it is known that the difference between the original required C / N and the actual required C / N (required C / N deterioration amount) shows a certain tendency with respect to the number of conditions. (For example, see Non-Patent Document 1).

  This tendency can be applied when the condition number is constant in each carrier in the band, but it is difficult to apply when the condition number is not constant in each carrier in the band.

  FIG. 8 is a diagram showing the relationship between the average number of conditions in a band and the required C / N deterioration amount acquired in an actual field transmission experiment in a polarization MIMO transmission system. The horizontal axis represents the average condition number (dB) in the band, that is, the value obtained by averaging the condition numbers of the carriers in the band. The vertical axis represents the required C / N deterioration amount (dB). Circles are acquired samples, and α is a curve showing the tendency of both set based on the acquired samples.

  In FIG. 8, a curve α shows the characteristic of the required C / N deterioration amount when the condition number is constant in the band, and represents the ideal value of the required C / N deterioration amount with respect to the condition number. In addition, it can be seen from FIG. 8 that there are samples that deviate significantly from the curve α. These are samples whose condition number is not constant but fluctuating within the band.

  FIG. 9 is a diagram showing frequency characteristics of the condition number at the measurement points where the condition number is not constant in the band. The horizontal axis represents the frequency of the band, and the vertical axis represents the condition number. It can be seen from FIG. 9 that the number of conditions is not constant within the band at this measurement point.

  According to Non-Patent Document 1 described above, the conventional reception quality measuring apparatus is supposed to obtain the required C / N deterioration amount with respect to the average condition number in the band. That is, the conventional reception quality measuring apparatus calculates the condition number for each carrier in the band from the transmission line matrix of the MIMO transmission line, and obtains the average value of the condition numbers in the band (average condition number in the band). The required C / N deterioration amount for the average condition number is calculated.

JP, 2012-15922, A

"MIMO performance and condition number in LTE test", [online], Agilent Technologies, Inc. [Search February 15, 2016], Internet <http://cp.literature.agilent.com/litweb/pdf /5990-4759JAJP.pdf>

  However, the required C / N deterioration amount obtained by the conventional reception quality measuring apparatus is the required C / N deterioration amount when the number of conditions is constant in the band among the samples acquired in the transmission experiment shown in FIG. It is only at the sample points of the curve α showing the characteristics of.

  As described above, in the conventional reception quality measuring apparatus, among the samples acquired in the transmission experiment shown in FIG. 8, the samples that are largely deviated from the curve α, that is, the condition number is not constant and fluctuates within the band. The required C / N deterioration amount of the existing sample cannot be obtained.

  As shown in FIG. 8, the required C / N deterioration amount in the case where the number of conditions is not constant and has a large variation in the band is different from the required C / N deterioration amount in the case where the number of conditions is constant in the band. Will grow. In this case, as shown in FIG. 7B, the actual required C / N greatly varies from the original required C / N, making it difficult to estimate the actual required C / N.

  In terrestrial digital broadcasting, the propagation environment is not good because it is easily affected by reflection or shielding due to buildings or terrain. Therefore, in order to select a device that realizes stable reception or give improvement guidance so that stable reception is possible, it is necessary to accurately measure the reception quality at that point.

  Then, this invention is made in order to solve the said subject, The objective is to provide the receiving quality measuring apparatus and program which can measure the receiving quality of a specific point correctly in a MIMO transmission system. is there.

  In order to solve the problem, the reception quality measuring apparatus according to claim 1 receives a signal transmitted via a transmission antenna including a plurality of antennas via a MIMO transmission path and a reception antenna including a plurality of antennas. In a reception quality measuring device that measures reception quality at a predetermined point based on a received signal, a transmission line estimation unit that estimates a transmission line matrix of the MIMO transmission line for each carrier in the band based on the received signal. And a condition number calculation unit that calculates a condition number for each carrier in the band based on the transmission line matrix estimated by the transmission line estimation unit, and the condition number calculated by the condition number calculation unit The required C / N deterioration amount corresponding to the condition number and the required C / N deterioration amount corresponding to the condition number are stored in a table, or the required number of conditions and the required C / N deterioration amount corresponding to the condition number are inferior. Using a mathematical expression in which the relationship of the amount is defined, it is specified for each carrier within the band, the required C / N deterioration amount for each carrier within the band is averaged within the band, and the average required C / N within the band is calculated. And a required C / N calculator for obtaining the deterioration amount.

  The reception quality measuring apparatus according to claim 2 is the reception quality measuring apparatus according to claim 1, further comprising: a C / N calculating section for calculating a reception C / N based on the received signal, and the required C. The average required C / N deterioration amount within the band obtained by the / N calculating unit is added to the preset original required C / N to obtain the actual required C / N, and the calculated required C / N is calculated by the C / N calculating unit. And a margin calculating unit that calculates the margin by subtracting the actual required C / N from the received C / N.

  Further, the reception quality measuring device according to claim 3 receives a horizontally polarized modulation signal and a vertically polarized modulation signal transmitted via a transmission antenna including a plurality of antennas, from a MIMO transmission line and a plurality of antennas. Received via an antenna, based on the received signal of horizontal polarization and the received signal of vertical polarization, in a reception quality measuring device for measuring the reception quality at a predetermined point, based on the received signal of the horizontal polarization, A reception power measuring unit for measuring the reception power of the horizontal polarization reception signal and measuring the reception power of the vertical polarization reception signal based on the vertical polarization reception signal, and the horizontal polarization reception signal C / N calculation for calculating the reception C / N of the horizontal polarization reception signal based on the above, and for calculating the reception C / N of the vertical polarization reception signal based on the vertical polarization reception signal Section and reception of the horizontal polarization Signal and the received signal of the vertically polarized wave, the received power of the received signal of the horizontally polarized wave and the received power of the received signal of the vertically polarized wave measured by the received power measuring unit, and the transmission through the transmitting antenna A transmission path estimation unit that estimates a transmission path matrix of the MIMO transmission path for each carrier in the band based on known signals included in the modulated signal of the horizontally polarized wave and the modulated signal of the vertically polarized wave, Corresponding to the condition number calculation unit that calculates the condition number for each carrier in the band based on the transmission line matrix estimated by the transmission line estimation unit, and the condition number calculated by the condition number calculation unit The required C / N deterioration amount is a table in which the number of conditions and the required C / N deterioration amount corresponding to the condition number are stored, or the relationship between the number of conditions and the required C / N deterioration amount corresponding to the condition number is Defined formula By using each carrier in the band, the required C / N deterioration amount for each carrier in the band is averaged in the band to calculate the average required C / N deterioration amount in the band. Section and the in-band average required C / N deterioration amount obtained by the required C / N calculation section are added to a preset original required C / N to obtain an actual required C / N. And a margin calculating section for calculating a margin by subtracting the actual required C / N from the received C / N calculated by the N calculating section.

  Furthermore, the reception quality measurement program according to claim 4 causes a computer to function as the reception quality measurement device according to any one of claims 1 to 3.

  As described above, according to the present invention, it is possible to accurately measure the reception quality at a specific point in a MIMO transmission system.

It is a block diagram which shows the structural example of the receiving quality measuring apparatus by embodiment of this invention. It is a block diagram which shows the structural example of a transmission path estimation part. It is a figure which shows the data structural example of a table. It is a figure which shows the required C / N deterioration amount (true value) acquired by the transmission experiment, and the required C / N deterioration amount acquired by the prior art and embodiment of this invention in each point of a field. It is a figure explaining the example of use of the receiving quality measuring device by an embodiment of the present invention. It is a figure explaining an example of a format of a transmission signal transmitted via a transmitting antenna. It is a figure which shows a mode that reception quality changes with propagation environments. FIG. 6 is a diagram showing the relationship between the average number of conditions in a band and the required C / N deterioration amount acquired in an actual field transmission experiment in a polarization MIMO transmission system. It is a figure which shows the frequency characteristic of a condition number in the measurement point where the condition number is not constant in a band.

Hereinafter, embodiments for carrying out the present invention will be described in detail with reference to the drawings.
[Outline of the present invention]
First, the outline of the present invention will be described. The present invention calculates the condition number for each carrier in the band, specifies the required C / N deterioration amount corresponding to the condition number for each carrier in the band, and averages the required C / N deterioration amount in the band. Therefore, the reception quality at a specific point is measured. By this means, it is possible to measure reception quality with high accuracy even when the number of conditions is not constant within the band but greatly fluctuates.

Hereinafter, a 2 × 2 MIMO transmission system using horizontal polarization and vertical polarization will be described as an example. The transmission antenna used for the MIMO transmission line is a polarization-polarized transmission antenna composed of a horizontal polarization antenna and a vertical polarization antenna, and the reception antenna is a polarization polarization shared of a horizontal polarization antenna and a vertical polarization antenna. It is a receiving antenna. The MIMO transmission path can be expressed as follows.

In the formula (1), Y _H is a horizontally polarized wave reception signal, Y _V is a vertically polarized wave reception signal, X _H is a horizontally polarized wave transmission signal, X _V is a vertically polarized wave transmission signal, and n is _H indicates noise of horizontal polarization, and n _V indicates noise of vertical polarization.

h _HH represents a transmission line characteristic between a horizontal polarization antenna element on the reception side (horizontal polarization antenna) and a horizontal polarization antenna element on the transmission side (horizontal polarization antenna). h _VV represents the transmission path characteristic between the vertically polarized antenna element on the receiving side (vertical polarized antenna) and the vertically polarized antenna element on the transmitting side (vertical polarized antenna).

h _HV represents the transmission line characteristic between the receiving side horizontally polarized antenna element (horizontal polarized antenna) and the transmitting side vertically polarized antenna element (vertically polarized antenna). Corresponds to the transmission line characteristics of the signal leaking from the horizontal polarization. h _VH indicates the transmission line characteristic between the receiving side vertically polarized antenna element (vertical polarized wave antenna) and the transmitting side horizontally polarized antenna element (horizontal polarized wave antenna). Corresponds to the transmission line characteristic of the signal leaking from the vertical polarization.

A transmission line matrix H is generated by using these transmission line characteristics h _HH , h _VV , h _HV , and h _VH as elements, as in the following formula.

ここで、条件数Ｋ（Ｈ）は１以上の値をとる。条件数Ｋ（Ｈ）が１に近い小さい値の場合、伝送路行列Ｈは良条件の行列であり、精度の高いＭＩＭＯ復調を実現できることを示している。一方、条件数Ｋ（Ｈ）が大きい値の場合、伝送路行列Ｈは悪条件の行列であり、精度が低く誤差の生じるＭＩＭＯ復調が実現されることを示している。 The condition number K (H) is the maximum value λ _max and the minimum value λ _min among the first eigenvalue λ ₁ and the second eigenvalue λ ₂ obtained by eigenvalue decomposition of the transmission line matrix H, as in the following formula. It is calculated by the ratio between.

Here, the condition number K (H) takes a value of 1 or more. When the condition number K (H) is a small value close to 1, the transmission line matrix H is a well-conditioned matrix, which shows that highly accurate MIMO demodulation can be realized. On the other hand, when the condition number K (H) has a large value, the transmission channel matrix H is a badly conditioned matrix, and it is shown that MIMO demodulation with low accuracy and error is realized.

If the MIMO transmission path is ideal, the reception gain of the horizontal polarization antenna and the reception gain of the vertical polarization antenna that form the reception antenna are completely the same, and the signal leaking to the cross polarization is minimal, It is expressed by the following formula. In this case, it is possible to ideally separate the received signal by MIMO demodulation and restore the transmitted signal.

  However, for example, due to the difference in directivity between the horizontal polarization antenna and the vertical polarization antenna forming the reception antenna, the difference in reception gain between the horizontal polarization and the vertical polarization (reception Level difference) may occur. When there is a signal leaking into cross-polarized waves, this reception level difference becomes the difference between the element values at the diagonal positions of the transmission line matrix H, and the condition number K (H) becomes a large value that is not close to 1 As a result, the required C / N deteriorates. That is, the smaller the condition number K (H), the smaller the deterioration of the required C / N due to the difference in the reception levels of both antennas, and the larger the condition number K (H), the larger the deterioration of the required C / N. There is.

  Therefore, in the embodiment of the present invention, the required C / N deterioration amount is determined for each carrier in the band by using a table in which the relationship between the condition number K (H) and the required C / N deterioration amount is defined. The reception quality is measured by specifying and averaging the required C / N deterioration amount within the band. The relationship between the condition number K (H) and the required C / N deterioration amount varies depending on the system requirements such as the modulation multi-level number and error correction code, but is calculated by computer simulation or experiment in a specific MIMO transmission system. be able to.

  Conventionally, the reception quality is measured on the assumption that the condition number is constant in the band, but in the embodiment of the present invention, the reception quality is measured on the assumption that the condition number is different for each carrier in the band. To do.

  As a result, when the number of conditions is not constant in the band and the fluctuation is large, the required C / N deterioration amount in the band calculated by the embodiment of the present invention (the required C / N deterioration amount for each carrier is averaged. The value) is a more accurate value than the required C / N deterioration amount in the band calculated by the conventional technique (the required C / N deterioration amount obtained by using the average condition number in the band). Therefore, according to the embodiments of the present invention, it is possible to accurately measure the reception quality at a specific point in a MIMO transmission system.

[Reception quality measuring device]
Hereinafter, a reception quality measuring device according to an exemplary embodiment of the present invention will be described. For simplification of description, an example of measuring the reception quality at a specific point in a 2 × 2 polarization MIMO transmission system will be described. It is assumed that the transmission signal transmitted via the transmission antenna on the transmission side is a modulation signal such as OFDM or single carrier.

  The transmitting side transmits a horizontally polarized signal and a vertically polarized signal including a known signal (for example, a pilot signal) for estimating the transmission path via the transmitting antenna. The reception quality measuring device on the receiving side receives the horizontally polarized signal and the vertically polarized signal transmitted from the transmitting side via the receiving antenna. The transmitting antenna is composed of a horizontally polarized antenna and a vertically polarized antenna, and the receiving antenna is also composed of a horizontally polarized antenna and a vertically polarized antenna.

  FIG. 6 is a diagram illustrating an example of a format of a transmission signal transmitted via the transmission antenna. FIG. 6A shows the format of a signal (horizontal polarization transmission signal) transmitted from the horizontal polarization antenna of the transmission antenna, and FIG. 6B shows the format of the signal transmitted from the vertical polarization antenna of the transmission antenna. The format of the signal (vertically polarized transmission signal) is shown. The horizontal axis represents frequency (carrier number), and the vertical axis represents time (symbol number). The signal at the position shown in black is a known SP (Scattered Pilot) signal, the signal at the position shown by a diagonal horizontal line is a known null signal, and the signal at the position shown in white is The data.

  In the horizontal polarization transmission signal of FIG. 6A, the SP signal and the null signal, which are reference signals, are arranged at predetermined frequency intervals and time intervals, and even in the vertical polarization transmission signal of FIG. The SP signal and the null signal are arranged at the same predetermined frequency interval and time interval. A null signal in the vertically polarized transmission signal of FIG. 6B is arranged at a position where the SP signal is arranged in the horizontally polarized transmission signal of FIG. 6A. Further, the SP signal in the vertically polarized transmission signal of FIG. 6B is arranged at the position where the null signal is arranged in the horizontally polarized transmission signal of FIG. 6A.

  By arranging the SP signal and the null signal as described above, it is possible to provide orthogonality between the horizontal polarized wave and the vertical polarized wave. Therefore, the reception quality measuring device on the receiving side is arranged between the transmitting antenna and the receiving antenna. Each element of the transmission line matrix H can be calculated individually.

  FIG. 1 is a block diagram showing a configuration example of a reception quality measuring apparatus according to an embodiment of the present invention. The reception quality measuring apparatus 1 includes reception power measuring units 10-1 and 10-2, C / N calculating units 11-1 and 11-2, a transmission path estimating unit 12, a condition number calculating unit 13, a table 14, and a required C. A / N calculator 15, a margin calculator 16, and a measurement result output unit 17 are provided.

  The reception quality measuring apparatus 1 receives a modulated signal such as OFDM or a single carrier transmitted via a transmission antenna on the transmission side via a reception antenna (not shown). As described above, this modulated signal includes a known signal (for example, pilot signal) for estimating the transmission line matrix H. The receiving antenna is composed of an antenna for horizontal polarization and an antenna for vertical polarization.

The reception quality measuring device 1 inputs the reception signal Y _H received via the horizontal polarization antenna and the reception signal Y _V received via the vertical polarization antenna. The reception quality at the point of the reception quality measuring device 1 is measured based on Y _H and Y _V.

The reception power measuring unit 10-1 inputs the reception signal Y _H received via the reception antenna and measures the reception power P _H based on the reception signal Y _H. Then, the reception power measurement unit 10-1 outputs the reception power P _H to the transmission path estimation unit 12 and the measurement result output unit 17.

The reception power measuring unit 10-2 inputs the reception signal Y _V received via the reception antenna and measures the reception power P _V based on the reception signal Y _V. Then, the reception power measurement unit 10-2 outputs the reception power P _V to the transmission path estimation unit 12 and the measurement result output unit 17.

C / N calculation section 11-1 receives the received signal Y _H, calculates the reception C / N _H based on the received signal Y _H. Then, the C / N calculation unit 11-1 outputs the received C / N _H to the margin calculation unit 16 and the measurement result output unit 17.

C / N calculation section 11-2 receives the received signal Y _V, calculates a reception C / N _V based on the received signal Y _V. Then, the C / N calculation unit 11-2 outputs the received C / N _V to the margin calculation unit 16 and the measurement result output unit 17.

The transmission path estimation unit 12 inputs the received signals Y _H and Y _V, and the received powers P _H and P _V from the received power measuring units 10-1 and 10-2. Then, the transmission path estimation unit 12 receives the horizontally polarized wave and the vertically polarized wave based on the received signals Y _H and Y _V , the received powers P _H and P _V , and the preset known signals X _H and X _V. A transmission line matrix H ′ accurately reflecting the power difference is estimated. The transmission channel estimation unit 12 outputs the transmission channel matrix H ′ to the condition number calculation unit 13.

The preset known signals X _H and X _V are the same as the signals included in the modulated signal transmitted from the transmitting side via the transmitting antenna, and are signals for estimating the transmission path (see FIG. 6). SP signal and null signal in the example). These are a horizontally polarized known signal and a vertically polarized known signal, respectively.

When the above-mentioned formula (1), which represents the MIMO transmission path by a formula, is developed, the horizontal polarization reception signal Y _H and the vertical polarization reception signal Y _V are expressed by the following formulas. The noises n _H and n _V are 0.

The transmission path estimation unit 12 calculates the transmission path characteristics h _HH , h _VV , h _HV , and h _VH , and with respect to the transmission path matrix H having these as elements, accurately calculates the received power difference between the horizontal polarization and the vertical polarization. Estimate the transmission path matrix H'reflected in the above.

  FIG. 2 is a block diagram showing a configuration example of the transmission path estimation unit 12. The transmission path estimation unit 12 includes frequency conversion units 20-1 and 20-2, A / D conversion units 21-1 and 21-2, FFT units 22-1 and 22-2, and pilot extraction units 23-1 and 23. -2, a known signal generation unit 24, transmission line characteristic calculation units 25-1, 25-2, and a transmission line matrix calculation unit 26.

Frequency conversion unit 20-1 receives the received signal Y _H, and converted into a frequency for A / D conversion the frequency of the received signal Y _H at a subsequent stage of the A / D conversion unit 21-1, a frequency converter The subsequent reception signal Y _H is output to the A / D conversion unit 21-1.

The A / D conversion unit 21-1 receives the frequency-converted reception signal Y _H from the frequency conversion unit 20-1, A / D converts an analog signal of the reception signal Y _H into a digital signal, and receives the digital reception signal. and it outputs the Y _H to the FFT unit 22-1.

The FFT unit 22-1 inputs the digital reception signal Y _H from the A / D conversion unit 21-1, converts the time domain signal of the digital reception signal Y _H into a frequency domain signal, and extracts the frequency domain signal as a pilot. It is output to the unit 23-1.

  The pilot extraction unit 23-1 receives the frequency domain signal from the FFT unit 22-1, extracts the pilot signal (SP signal and null signal) at the position where the known signal is transmitted from the frequency domain signal, and receives the received pilot signal. To the transmission path characteristic calculation unit 25-1.

The known signal generation unit 24 generates a preset known signal (SP signal and null signal shown in FIG. 6), and outputs the known signals X _H and X _V to the transmission path characteristic calculation units 25-1 and 25-2. Output.

The transmission path characteristic calculation unit 25-1 inputs the received pilot signal from the pilot extraction unit 23-1 and the known signals X _H and X _V (transmission pilot signals) from the known signal generation unit 24. Then, the transmission path characteristic calculation unit 25-1 divides the received pilot signal by the transmission pilot signal to calculate the transmission path characteristics h _HH and h _HV which are the frequency characteristics of the MIMO transmission path, and the transmission path characteristics h _HH and h _{The HV} is output to the transmission path matrix calculation unit 26.

Since the known signal transmitted from the transmitting side maintains the orthogonality between the horizontal polarization and the vertical polarization, the transmission path characteristics h _HH and h in the first and second terms of the equation (5). _HV can be isolated. Thereby, the transmission path characteristics h _HH and h _HV among the elements forming the transmission path matrix H are individually calculated from the received signal Y _H.

The frequency conversion unit 20-2, the A / D conversion unit 21-2, the FFT unit 22-2, and the pilot extraction unit 23-2 use the above-described frequency conversion unit 20-1 and A / D conversion unit for the reception signal Y _V. 21-1, the FFT unit 22-1, and the pilot extraction unit 23-1, respectively, perform the same processing.

The transmission line characteristic calculation unit 25-2 also performs the same processing as the above-described transmission line characteristic calculation unit 25-1. Transmission channel characteristic calculation unit 25-2 receives inputs the received pilot signal from the pilot extraction unit 23-2, a known signal from known signal generating unit 24 X _H, X _V (transmission pilot signal), channel characteristics Calculate h _VV and h _VH . Then, the transmission line characteristic calculation unit 25-2 outputs the transmission line characteristics h _VV and h _VH to the transmission line matrix calculation unit 26.

Since the known signal transmitted from the transmission side maintains the orthogonality between the horizontal polarization and the vertical polarization, the transmission line characteristics h _VH and h in the first and second terms of the mathematical expression (6). _VV can be separated. Thereby, the transmission path characteristics h _VV and h _VH among the elements forming the transmission path matrix H are individually calculated from the received signal Y _V.

The transmission line matrix calculation unit 26 inputs the transmission line characteristics h _HH and h _HV from the transmission line characteristic calculation unit 25-1, and inputs the transmission line characteristics h _VV and h _VH from the transmission line characteristic calculation unit 25-2. Further, the received powers P _H and P _V are input from the received power measuring units 10-1 and 10-2. Then, the transmission path matrix calculation unit 26 calculates the powers P ′ _H and P ′ _V of the transmission path characteristics h _HH and h _VV based on the transmission path characteristics h _HH and h _VV , respectively.

The transmission line matrix calculation unit 26 calculates the transmission line characteristics h _HH , h _HV , h _VV , h _VH , the received powers P _H , P _V, and the powers P ′ _H , P ′ _V by the following mathematical formulas. The matrix H'is calculated. Then, the transmission path matrix calculation unit 26 outputs the transmission path matrix H ′ to the condition number calculation unit 13.

  As a result, the power-corrected transmission line matrix H'that accurately reflects the received power difference between the horizontal polarization and the vertical polarization is calculated. This transmission line matrix H'is obtained for each carrier in the entire band.

  Returning to FIG. 1, the condition number calculation unit 13 inputs the transmission line matrix H ′ for each carrier from the transmission line estimation unit 12, and calculates the condition number K (H ′) based on the transmission line matrix H ′. This condition number K (H ') is obtained for each carrier in the entire band. Then, the condition number calculation unit 13 outputs the condition number K (H ′) for each carrier to the required C / N calculation unit 15.

There are a plurality of methods for calculating the condition number K (H ′), such as singular value decomposition and eigenvalue decomposition. For example, refer to the following documents for the eigenvalue decomposition method of the Hermitian matrix.
"Hermitian matrix eigenvalue decomposition algorithm", [online], [February 15, 2016 search], Internet <http://kosugitti.sakura.ne.jp/wp/wp-content/uploads/2013/08/ qr.pdf>

  The table 14 stores the number of conditions and the required C / N deterioration amount. FIG. 3 is a diagram showing a data configuration example of the table 14. The table 14 stores the number of conditions and the required C / N deterioration amount corresponding to the number of conditions. These data are a table of the curve α shown in FIG. 8 when the condition number is constant in the band, and the required C / N deterioration amount represents an ideal value for the condition number. This table 14 is preset.

  Returning to FIG. 1, the required C / N calculation unit 15 inputs the condition number K (H ′) for each carrier from the condition number calculation unit 13 and creates a table using the condition number K (H ′) as a key for each carrier. 14 is searched, and the required C / N deterioration amount corresponding to the condition number K (H ′) is read.

  The required C / N calculation unit 15 calculates the average value of the required C / N deterioration amount (in-band average required C / N deterioration amount) D within the band, and reserves the in-band average required C / N deterioration amount D. It is output to the degree calculation unit 16.

When the required C / N deterioration amount corresponding to the condition number K (H ′) in the carrier number n is deg (n), the number of carriers in the band is N, and the average required C / N deterioration amount in the band D is deg, The deg, which is the in-band average required C / N deterioration amount D, is calculated by the following mathematical expression.

The margin calculation unit 16 inputs the in-band average required C / N deterioration amount D from the required C / N calculation unit 15, and receives C / N _H and reception from the C / N calculation units 11-1 and 11-2. C / N _V is input, the average value of the received C / N _H and the received C / N _V is calculated, and this is set as the received C / N.

The margin calculating unit 16 adds the in-band average required C / N deterioration amount D to the actual required C / N by using the following mathematical expression, and adds to the original required C / N preset in the MIMO transmission system. Find N. As a result, the actual required C / N at the point of the reception quality measuring device 1 can be calculated with high accuracy.
[Equation 9]
Actual required C / N = Original required C / N + In-band average required C / N Deterioration amount D
... (9)

The margin calculating unit 16 calculates the margin F by subtracting the actual required C / N calculated by the above equation (9) from the received C / N by the following mathematical expression, and calculates the margin F. It is output to the measurement result output unit 17. Thereby, the margin F at the point of the reception quality measuring device 1 can be calculated with high accuracy.
[Equation 10]
Margin F = reception C / N−actual required C / N (10)

Measurement result output unit 17 inputs the received power P _V of the received power P _H and the received signal Y _V of the received signal Y _H from the received power measurement section 10-1 and 10-2, C / N calculation section 11 inputs the received C / N _V of the receiving C / N _H and the received signal Y _V of the received signal Y _H from 1,11-2. Further, the measurement result output unit 17 inputs the allowance F from the allowance calculator 16.

Measurement result output unit 17, the received power P _H of the received signal Y _H, the received power P _V of the received signal Y _V, reception C / N _H of the received signal Y _H, the reception C / N _V of the received signal Y _V, and The margin F is output as the measurement result of the reception quality at the point of the reception quality measuring device 1.

  FIG. 4 is a diagram showing the required C / N deterioration amount (true value) acquired in the transmission experiment, and the required C / N deterioration amount acquired in the prior art and the embodiment of the present invention at each point in the field. .. The horizontal axis indicates samples 1 to 8 at each point, and the vertical axis indicates the required C / N deterioration amount.

  In each of Samples 1 to 8, the bar on the left side shows the required C / N deterioration amount (true value) acquired in the transmission experiment, and corresponds to the required C / N deterioration amount shown in FIG. The center bar indicates the required C / N deterioration amount obtained by the conventional technique, which is the characteristic obtained by the conventional reception quality measuring apparatus, and is the required C / N deterioration of the curve α shown in FIG. Equivalent to the amount. As described above, the conventional reception quality measuring apparatus calculates the condition number for each carrier in the band from the transmission line matrix of the MIMO transmission line, and averages the condition numbers in the band (average condition number in the band). ) Is calculated, and the required C / N deterioration amount for the average condition number is calculated. The bar on the right side shows the required C / N deterioration amount acquired in the embodiment of the present invention.

  The required C / N deterioration amount (the bar on the right side) acquired in the embodiment of the present invention from the samples 1 to 8 in FIG. 4 is higher than the required C / N deterioration amount (the center bar) acquired by the conventional technique. It can be seen that it is close to the required C / N deterioration amount (true value, left bar) acquired in the transmission experiment. As a result, in the embodiment of the present invention, the required C / N deterioration amount can be obtained more accurately than in the related art.

  As described above, according to the reception quality measuring device 1 of the embodiment of the present invention, at the specific point where the reception quality is measured, the horizontal polarization and vertical polarization modulation signals including the known signal transmitted from the transmission side. Is received via the receiving antenna.

The transmission path estimation unit 12 reflects the received power difference between the horizontal polarized wave and the vertical polarized wave based on the received signals Y _H and Y _V , the received powers P _H and P _V, and the known signals X _H and X _V. Estimate the road matrix H '. As a result, the transmission path matrix H ′ for each carrier at the point of the reception quality measuring apparatus 1 is obtained.

  The condition number calculation unit 13 calculates the condition number K (H ') based on the transmission line matrix H'. As a result, the condition number K (H ') for each carrier at the point of the reception quality measuring apparatus 1 is obtained.

  The required C / N calculation unit 15 stores, for each carrier, the required C / N deterioration amount corresponding to the condition number K (H ′), the condition number, and the required C / N deterioration amount corresponding to the condition number. Read from table 14. Then, the required C / N calculation unit 15 calculates the average value of the required C / N deterioration amount within the band as the in-band average required C / N deterioration amount D. As a result, the in-band average required C / N deterioration amount D at the point of the reception quality measuring apparatus 1 is obtained.

The margin calculating unit 16 calculates the actual required C / N by adding the in-band average required C / N deterioration amount D to the original required C / N, and determines the received C / N (received C / N _H and The margin F is calculated by subtracting the actual required C / N from the average value of the received C / N _V ). Thereby, the margin F at the point of the reception quality measuring device 1 is obtained.

  As described above, the reception quality measuring apparatus 1 obtains the condition number K (H ′) for each carrier in the band at the point of the reception quality measuring apparatus 1 and specifies the required C / N deterioration amount corresponding to this. The required C / N deterioration amount is averaged within the band. As a result, a more accurate in-band average required C / N deterioration amount D is calculated even when the number of conditions is not constant and changes greatly within the band. Therefore, since the margin F at the point of the reception quality measuring apparatus 1 is calculated based on the more accurate in-band average required C / N deterioration amount D, the reception quality at the specific point is accurately calculated in the MIMO transmission system. It becomes possible to measure.

  In addition, since the margin F of the reception quality can be accurately measured in the terrestrial digital broadcasting area, as a result, a device that realizes stable reception can be selected and stable reception is possible. You can give improvement guidance so that

  FIG. 5 is a diagram illustrating a usage example of the reception quality measuring device 1 according to the embodiment of the present invention. The operator who installs the reception antenna has the reception quality measuring apparatus 1, and in order to obtain the reception quality at a specific point which is the point of the reception quality measuring apparatus 1, the reception quality measuring apparatus 1 is installed. Aim the antenna in the specified direction.

The reception quality measuring device 1 includes a display unit that displays the measurement result measured by the measurement result output unit 17. As shown in the lower part of FIG. 5, the display section displays the reception level (average value of the reception powers P _H and P _V ), the reception C / N, and the margin for each of the directions A, B, and C of the reception antennas. Display F and acceptability. The display unit compares the allowance with a predetermined value, and when the allowance F is equal to or larger than the predetermined value, displays a mark ◎ indicating that the reception is possible as a result of the reception availability determination, and the allowance F is smaller than the predetermined value. In this case, a mark x indicating that reception is impossible is displayed.

  In FIG. 5, the display unit displays reception enable / disable in the reception enable / disable position when the reception antenna is in the direction A, and displays reception disable / use in the reception enable / disable position in the reception antenna directions B and C. Thereby, the operator determines that the reception quality at the point of the reception quality measuring apparatus 1 in the direction A of the receiving antenna is better than that at the point of the reception quality measuring apparatus 1 in the directions B and C of the receiving antenna. can do.

  Thus, the reception quality measuring device 1 continuously measures the margin F, so that the operator can determine the direction of the antenna in which the margin F is maximum. Then, it is possible to improve the reception such as the adjustment of the direction of the antenna and to examine the replacement of the equipment, which can contribute to the stable reception of the MIMO transmission system. Particularly, in the polarization MIMO transmission system, the reception level and the reception C / N are measured for two signals of the horizontal polarization and the vertical polarization, so that the value for judging the reception quality increases. However, in the embodiment of the present invention, since the margin F is measured, it is possible to clearly judge the reception quality by the margin F.

  Although the present invention has been described above with reference to the exemplary embodiments, the present invention is not limited to the above-described exemplary embodiments, and various modifications can be made without departing from the technical idea thereof. For example, the embodiment has described the 2 × 2 MIMO transmission system using the horizontal polarization and the vertical polarization. The present invention does not limit the number of transmitting antennas to two and the number of receiving antennas to two, and is applicable to other numbers. Further, the present invention is not limited to horizontal polarized waves and vertical polarized waves, but may be applied to other types of polarized waves and also to radio waves other than polarized waves.

  Further, in the embodiment of the present invention, the format of the transmission signal shown in FIG. 6 is used, but the present invention is not limited to the format of the transmission signal shown in FIG. 6, and an arrangement different from this is used. You may make it use the format of. Further, another pilot signal may be used, or a known signal continuously inserted in the frequency axis and time axis directions may be used. Further, as an orthogonalization method, a Hadamard code or an Alamouti code may be used instead of the null signal.

  Further, in the embodiment of the present invention, the required C / N calculation unit 15 of the reception quality measuring device 1 reads out the required C / N deterioration amount corresponding to the condition number K (H ′) from the table 14. On the other hand, the required C / N calculation unit 15 may specify the required C / N deterioration amount corresponding to the condition number K (H ′) according to a mathematical expression of a preset function.

In the embodiments of the present invention, the measurement result output section 17 of the reception quality measuring apparatus 1, the received power P _H of the received signal Y _H, the received power P _V of the received signal Y _V, the received signal Y _H of the received C / N _H, the reception C / N _V of the received signal Y _V, and the margin F, and output as the measurement result of the reception quality. On the other hand, the measurement result output unit 17 further includes the in-band average required C / N deterioration amount D calculated by the required C / N calculation unit 15 and the condition number K (H) calculated by the condition number calculation unit 13. ') May be output as the measurement result of the reception quality.

  Further, although the reception quality measuring apparatus 1 has been described in the embodiment of the present invention, the MIMO receiving apparatus may include each component of the reception quality measuring apparatus 1 shown in FIG. In this case, the MIMO receiving apparatus has a function of displaying the measurement result of the margin F and the like.

  A normal computer can be used as the hardware configuration of the reception quality measuring device 1 according to the embodiment of the present invention. The reception quality measuring device 1 is configured by a computer including a CPU, a volatile storage medium such as a RAM, a non-volatile storage medium such as a ROM, and an interface. Received power measurement units 10-1 and 10-2, C / N calculation units 11-1 and 11-2, a transmission path estimation unit 12, a condition number calculation unit 13, a table 14, a required C included in the reception quality measurement device 1. Each function of the / N calculation unit 15, the margin calculation unit 16, and the measurement result output unit 17 is realized by causing the CPU to execute a program that describes these functions. Also, these programs (reception quality measurement programs) should be stored and distributed in storage media such as magnetic disks (floppy (registered trademark) disks, hard disks, etc.), optical disks (CD-ROM, DVD, etc.), semiconductor memories, etc. It can also be sent and received via a network.

1 reception quality measuring device 10 reception power measuring unit 11 C / N calculating unit 12 transmission path estimating unit 13 condition number calculating unit 14 table 15 required C / N calculating unit 16 margin calculation unit 17 measurement result output unit 20 frequency converting unit 21 A / D conversion unit 22 FFT unit 23 Pilot extraction unit 24 Known signal generation unit 25 Transmission line characteristic calculation unit 26 Transmission line matrix calculation unit

Claims (4)

Reception quality measurement in which a signal transmitted via a transmission antenna including a plurality of antennas is received via a MIMO transmission path and a reception antenna including a plurality of antennas, and the reception quality at a predetermined point is measured based on the reception signals. In the device,
A transmission path estimation unit that estimates a transmission path matrix of the MIMO transmission path for each carrier in the band based on the received signal,
A condition number calculation unit that calculates a condition number for each carrier in the band based on the transmission line matrix estimated by the transmission line estimation unit;
The required C / N deterioration amount corresponding to the condition number calculated by the condition number calculation unit is stored in the table in which the condition number and the required C / N deterioration amount corresponding to the condition number are stored, or Using a mathematical expression in which the relationship of the required C / N deterioration amount corresponding to the number of conditions is defined, it is specified for each carrier within the band, and the required C / N deterioration amount for each carrier within the band is determined within the band. A required C / N calculator for averaging and obtaining an average required C / N deterioration amount in the band;
A reception quality measuring device comprising: In the reception quality measuring device according to claim 1,
Furthermore, a C / N calculator for calculating a received C / N based on the received signal,
The in-band average required C / N deterioration amount obtained by the required C / N calculation unit is added to a preset original required C / N to obtain an actual required C / N, and the C / N calculation unit A margin calculating section for calculating a margin by subtracting the actual required C / N from the received C / N calculated by
A reception quality measuring device comprising: The horizontally polarized wave modulated signal and the vertically polarized wave modulated signal transmitted through the transmitting antenna including the plurality of antennas are received through the MIMO transmission path and the receiving antenna including the plurality of antennas, and the horizontally polarized wave is received. In the reception quality measuring device for measuring the reception quality at a predetermined point, based on the signal and the received signal of vertical polarization,
Reception for measuring the reception power of the reception signal of the horizontal polarization based on the reception signal of the horizontal polarization and measuring the reception power of the reception signal of the vertical polarization based on the reception signal of the vertical polarization An electric power measurement unit,
The reception C / N of the reception signal of the horizontal polarization is calculated based on the reception signal of the horizontal polarization, and the reception C / N of the reception signal of the vertical polarization is calculated based on the reception signal of the vertical polarization. A C / N calculator for calculating
The reception signal of the horizontal polarization and the reception signal of the vertical polarization, the reception power of the reception signal of the horizontal polarization and the reception power of the reception signal of the vertical polarization measured by the reception power measuring unit, and A transmission path matrix of the MIMO transmission path is estimated for each carrier in a band based on known signals included in the horizontal polarization modulation signal and the vertical polarization modulation signal transmitted via a transmission antenna. A transmission line estimation unit,
A condition number calculation unit that calculates a condition number for each carrier in the band based on the transmission line matrix estimated by the transmission line estimation unit;
The required C / N deterioration amount corresponding to the condition number calculated by the condition number calculation unit is stored in the table in which the condition number and the required C / N deterioration amount corresponding to the condition number are stored, or Using a mathematical expression in which the relationship of the required C / N deterioration amount corresponding to the number of conditions is defined, it is specified for each carrier within the band, and the required C / N deterioration amount for each carrier within the band is determined within the band. A required C / N calculator for averaging and obtaining an average required C / N deterioration amount in the band;
The in-band average required C / N deterioration amount obtained by the required C / N calculation unit is added to a preset original required C / N to obtain an actual required C / N, and the C / N calculation unit A margin calculation unit that calculates a margin by subtracting the actual required C / N from the received C / N calculated by
A reception quality measuring device comprising:   A reception quality measurement program for causing a computer to function as the reception quality measurement device according to any one of claims 1 to 3.

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