JP2017183921A - Measuring apparatus, measuring method, and program - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress reduction of a measurement accuracy of a modulation error ratio even when using an ununiformity constellation.SOLUTION: A measuring apparatus 10 according to the present invention, comprises a measurement part 14 that is part for receiving a signal to which data is mapped in a signal point on an ununiformity constellation to which the signal point is arranged on an IQ flat surface in ununiformity, and measuring a modulation error ratio (MER) indicating an error of the reception signal and the signal point on the ununiformity constellation, and measures the modulation error ratio of the reception signal corresponding to the signal point of a part of the ununiformity constellation.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a measuring apparatus, a measuring method, and a program for measuring a modulation error ratio indicating an error between a received signal mapped on IQ coordinates and an ideal signal point in a transmission method using a non-uniform constellation.

  Conventionally, in mapping processing for assigning multiple bits of data to IQ coordinate values (signal points) on the IQ plane, a constellation (set of IQ coordinate values) with uniform intervals between signal points has been used. On the receiving side, in general, all signal points on the constellation are used, and the received signal quality, specifically, a modulation error ratio (MER: Modulation Error) indicating an error between the received signal and an ideal signal point. Ratio) was measured.

  In recent years, for the purpose of improving transmission characteristics, non-uniform constellation (NUC: Non-Uniform Constellation) with non-uniform constellation of signal points on the IQ plane has been introduced in ATSC 3.0, which is a US terrestrial digital broadcasting system. It has been studied (see Non-Patent Document 1).

“A / 322: ATSC Candidate Standard-Physical Layer Protocol” [searched on February 9, 2016], Internet <URL: http://atsc.org/wp-content/uploads/2015/10/S32-230r21- PHY-STD-CS.pdf>

  As described above, when a constellation with uniform intervals between signal points (uniform constellation) is used, MER is generally measured using all signal points. On the other hand, in the non-uniform constellation, the signal point intervals are non-uniform, and the signal point density also varies. Therefore, in a portion where the density of signal points is high, the MER is measured (calculated) higher than the actual value, and the measurement accuracy of the MER may decrease. In recent years, 4K and 8K Super Hi-Vision (SHV) has been developed as ultra-high-definition video exceeding Hi-Vision, and in such SHV, the modulation multi-level number is increased in order to increase the transmission amount of data per unit time. A large modulation scheme is used. In such a modulation method with a large number of modulation multi-values, the signal point interval becomes small, and the problem of a decrease in measurement accuracy becomes more conspicuous when MER is measured using all signal points.

  An object of the present invention is to provide a measuring apparatus, a measuring method, and a program capable of solving the above-described problems and suppressing a decrease in measurement accuracy of a modulation error ratio even when a non-uniform constellation is used. is there.

  In order to solve the above-described problems, the measurement apparatus of the present invention receives a signal in which data is mapped to signal points on a non-uniform constellation in which signal points are non-uniformly arranged on an IQ plane, A measurement device for measuring a modulation error ratio indicating an error from a signal point on a uniform constellation, wherein the measurement unit measures the modulation error ratio for a received signal corresponding to some signal points of the non-uniform constellation. Is provided.

  In order to solve the above-described problem, in the measurement apparatus according to the present invention, the measurement unit may select signal points of signal points on the non-uniform constellation where signal point density is lower than other parts. The modulation error ratio is preferably measured for the corresponding received signal.

  In order to solve the above-described problem, in the measurement apparatus according to the present invention, the measurement unit includes signal points on the non-uniform constellation at signal points in a predetermined width from the outermost periphery toward the inside. The modulation error ratio is preferably measured for the corresponding received signal.

  In order to solve the above-described problem, in the measurement apparatus according to the present invention, the measurement unit is configured to process the received signal corresponding to a signal point within a predetermined range from a vertex among signal points on the non-uniform constellation. It is preferable to measure the modulation error ratio.

  In order to solve the above-described problem, in the measurement apparatus according to the present invention, the measurement unit is configured such that, among signal points on the non-uniform constellation, a distance between adjacent signal points is on the non-uniform constellation. Preferably, the modulation error ratio is measured for a received signal corresponding to a signal point in a portion larger than an average value of distances between adjacent signal points.

  In order to solve the above problem, the measurement method according to the present invention receives a signal in which data is mapped to signal points on a non-uniform constellation in which signal points are non-uniformly arranged on an IQ plane, and receives a received signal. Measuring a modulation error ratio indicating an error between a signal point on the non-uniform constellation and measuring the modulation error ratio for a received signal corresponding to some signal points of the non-uniform constellation To do.

  In order to solve the above problem, a program according to the present invention receives a signal in which data is mapped to signal points on a non-uniform constellation in which signal points are non-uniformly arranged on an IQ plane, The modulation error ratio is measured for a received signal corresponding to some signal points of the non-uniform constellation by a computer in a measuring apparatus that measures a modulation error ratio indicating an error with the signal point on the non-uniform constellation. To execute the process.

  According to the measurement apparatus, the measurement method, and the program according to the present invention, it is possible to suppress a decrease in the measurement accuracy of the modulation error ratio even when a non-uniform constellation is used.

It is a block diagram which shows the structural example of the measuring apparatus which concerns on one Embodiment of this invention. It is a figure which shows an example of a uniform constellation. It is a figure which shows an example of a non-uniform constellation. It is a figure for demonstrating an example of operation | movement of the measurement part shown in FIG. It is a figure for demonstrating another example of operation | movement of the measurement part shown in FIG.

  Embodiments of the present invention will be described below.

  FIG. 1 is a block diagram illustrating a configuration example of a measurement apparatus 10 according to an embodiment of the present invention. The measurement apparatus 10 according to the present embodiment receives a signal transmitted from the transmission side using a non-uniform constellation, and a modulation error ratio (which is an error between the received signal and an ideal signal point on the non-uniform constellation) MER). The measuring device 10 is used for measuring MER at each point in the broadcast area, for example. On the transmission side, for example, error correction using LDPC (Low Density Parity Check) code, mapping of data after error correction code to signal points on non-uniform constellation, orthogonal modulation after mapping, and the like are performed. However, since the configuration of such a transmission-side apparatus is well known to those skilled in the art and is not directly related to the present invention, a description thereof will be omitted.

  The measurement apparatus 10 illustrated in FIG. 1 includes an orthogonal demodulation unit 11, a channel estimation unit 12, an equalization unit 13, and a measurement unit 14.

  The quadrature demodulator 11 receives a received signal (Rx) received on the measuring apparatus 10 side from a signal transmitted from the transmitting side, and performs quadrature demodulation on the input received signal. Then, the orthogonal demodulation unit 11 outputs the signal after the orthogonal demodulation to the channel estimation unit 12 and the equalization unit 13.

  The channel estimation unit 12 performs channel estimation from a transmission path estimation signal (pilot signal) included in the output signal of the orthogonal demodulation unit 11 and outputs an estimated value to the equalization unit 13.

  The equalization unit 13 corrects (equalizes) and equalizes the distortion of the signal generated in the transmission path based on the estimated value of the channel estimation output from the channel estimation unit 12 with respect to the output signal of the orthogonal demodulation unit 11. The subsequent signal (received symbol: complex number on the IQ plane) is output to measurement section 14.

  The measurement unit 14 measures the MER for the output signal of the equalization unit 13. As described above, in this embodiment, data is mapped and transmitted to signal points on a non-uniform constellation in which signal points are non-uniformly arranged on the IQ plane. The measurement unit 14 measures MER by using some signal points on the non-uniform constellation instead of all signal points on the non-uniform constellation (corresponding to some signal points on the non-uniform constellation). MER is measured for the received signal).

  FIG. 2A is a diagram illustrating an example of a uniform constellation with uniform signal point intervals. FIG. 2B is a diagram illustrating an example of a non-uniform constellation in which signal point intervals are non-uniform. 2A and 2B show a constellation when the modulation method is 4096 QAM (Quadrature Amplitude Modulation).

  As shown in FIG. 2A, in the uniform constellation, 64 signal points (64 × 64) are arranged in the I-axis direction and the Q-axis direction, respectively, and the interval between adjacent signal points is the I-axis direction and the Q-axis. Uniform in direction. On the other hand, even in a non-uniform constellation, 64 signal points (64 × 64) are arranged in the I-axis direction and the Q-axis direction, respectively. As shown in FIG. Non-uniform in the axial direction and the Q-axis direction. Therefore, on the constellation, there are a portion where the signal point density is high (portion where the signal points are dense) and a portion where the signal point density is low (portion where the signal points are sparse). In FIG. 2B, some of the adjacent signal points are drawn so as to overlap, and the number of signal points in each of the I-axis direction and the Q-axis direction seems to be less than 64. , 64 signal points are arranged in each of the I-axis direction and the Q-axis direction.

  When MER is measured using signal points in a portion where the density of signal points is high, the measured MER is higher than the actual MER, and the measurement accuracy may decrease. Here, for example, it is known that MER can be measured with high accuracy when a modulation method with low signal point density such as BPSK (Binary Phase Shift Keying) is used. Therefore, the measurement unit 14 measures the MER using a part of signal points of the non-uniform constellation, more specifically, a part of signal points having a density of signal points lower than that of the other parts. By doing so, it is possible to suppress a decrease in the measurement accuracy of the MER.

  There are various methods for selecting signal points used by the measurement unit 14 for MER measurement. Below, the example of the selection method of the signal point used for the measurement of MER is demonstrated.

  FIG. 3 is an enlarged view of the first quadrant of the non-uniform constellation shown in FIG. 2B.

  As shown in FIG. 3, in the non-uniform constellation, the distance between signal points tends to increase from the center toward the outside. Therefore, the measurement unit 14 measures MER using signal points at a predetermined width from the outermost periphery of the non-uniform constellation toward the inside. For example, as shown in FIG. 3, the measurement unit 14 sets a boundary line between the outermost signal point and an inner signal point adjacent to the outermost signal point, and a portion outside the boundary line. MER is measured using the signal points included in 21. In addition, in FIG. 3, although it demonstrated using the example which makes only the outermost signal point the measuring object of MER, it is not restricted to this, If it is the density which can measure MER with high precision Alternatively, the MER may be measured by using signal points in the inner part of the outermost circumference several minutes.

  Even in the outermost periphery of the non-uniform constellation, as shown in FIG. 4, there are points where the interval between signal points is short and the density of signal points is high. Here, in the non-uniform constellation, there are cases where the distance between signal points is larger and the density is smaller in the vicinity of the vertex signal points. Therefore, as shown in FIG. 4, the measurement unit 14 excludes the portion 22 where the density of signal points is high even at the outermost periphery of the non-uniform constellation, and a predetermined range from the signal point at the apex of the non-uniform constellation. The MER may be measured using the signal points within. Since the position of each signal point of the non-uniform constellation is known, a portion where the density of signal points is high can be specified in advance.

  In addition, the measurement unit 14 is a signal of a portion in which the distance between adjacent signal points is larger than the average value of the distances between adjacent signal points on the non-uniform constellation among the signal points on the non-uniform constellation. The MER may be measured using points. By doing so, it is possible to measure the MER by selecting a portion where the density of signal points on the non-uniform constellation is low.

  As described above, according to the present embodiment, the measurement apparatus 10 includes the measurement unit 14 that measures the modulation error ratio (MER) for the reception signals corresponding to some signal points of the non-uniform constellation. By measuring the MER using some signal points instead of all the signal points of the non-uniform constellation, it is possible to measure the MER using the signal points of the part where the signal point density is low. A decrease in accuracy can be suppressed.

  The method performed by the measurement apparatus 10 according to the present invention may be applied to a program for causing a computer to execute. In addition, the program can be stored in a storage medium and can be provided to the outside via a network.

  Although the present invention has been described based on the drawings and embodiments, it should be noted that those skilled in the art can easily make various variations or modifications based on the present disclosure. Therefore, it should be noted that these variations or modifications are included in the scope of the present invention. For example, functions included in each block or step can be rearranged so as not to be logically contradictory, and a plurality of blocks or steps can be combined into one or divided.

DESCRIPTION OF SYMBOLS 10 Measuring apparatus 11 Orthogonal demodulation part 12 Channel estimation part 13 Equalization part 14 Measurement part

Claims (7)

A modulation error indicating an error between a received signal and a signal point on the non-uniform constellation by receiving a signal in which data is mapped to a signal point on a non-uniform constellation in which signal points are non-uniformly arranged on the IQ plane A measuring device for measuring the ratio,
A measurement apparatus comprising: a measurement unit that measures the modulation error ratio for a reception signal corresponding to a part of signal points of the non-uniform constellation. The measuring apparatus according to claim 1,
The measurement unit measures the modulation error ratio with respect to a received signal corresponding to a signal point of a signal point density lower than other portions among signal points on the non-uniform constellation. measuring device. The measuring apparatus according to claim 1 or 2,
The measurement unit measures the modulation error ratio with respect to a received signal corresponding to a signal point in a predetermined width portion from the outermost circumference toward the inside from signal points on the non-uniform constellation. measuring device. The measuring apparatus according to claim 1 or 2,
The measurement device is characterized in that the modulation error ratio is measured for a received signal corresponding to a signal point within a predetermined range from a vertex among signal points on the non-uniform constellation. The measuring apparatus according to claim 1 or 2,
The measurement unit is a signal of a portion of the signal points on the non-uniform constellation in which the distance between adjacent signal points is larger than the average value of the distances between adjacent signal points on the non-uniform constellation. A measuring apparatus for measuring the modulation error ratio for a received signal corresponding to a point. A modulation error indicating an error between a received signal and a signal point on the non-uniform constellation by receiving a signal in which data is mapped to a signal point on a non-uniform constellation in which signal points are non-uniformly arranged on the IQ plane A measuring method for measuring the ratio,
A measurement method comprising measuring the modulation error ratio for a received signal corresponding to a part of signal points of the non-uniform constellation. A modulation error indicating an error between a received signal and a signal point on the non-uniform constellation by receiving a signal in which data is mapped to a signal point on a non-uniform constellation in which signal points are non-uniformly arranged on the IQ plane In the computer in the measuring device that measures the ratio,
A program for executing a process of measuring the modulation error ratio for a received signal corresponding to a part of signal points of the non-uniform constellation.

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