JP5667742B2 - Antenna measurement system and method - Google Patents

Description

  The present invention relates to an antenna measurement system and method for evaluating antenna performance.

  In general, performance evaluation of a mobile communication antenna is performed by measuring radiation directivity in an anechoic chamber. In order to measure the radiation directivity, first, the antenna 1 to be measured is placed on the turntable 2 as shown in FIG. Then, by rotating the antenna 1 ′ to be measured, the radio wave corresponding to the electric signal is directed toward the antenna 1 ′ to be measured from the opposing antenna 3 ′ to which the electric signal is supplied from the external signal source at each angle. Radiate. Then, the received power of the antenna to be measured 1 'is measured for each angle. In this way, measurement of radiation directivity is realized.

  In particular, for mobile terminals, as a comprehensive radio performance evaluation including antennas, all-space radiated power measurement that measures the power radiated from a mobile terminal that actually operates using a pseudo base station device in all spaces, and from each direction There are two standards for measuring the reception sensitivity for all incoming waves, which measure the reception sensitivity for the entire space (see, for example, Non-Patent Document 1). With such a measurement system and measurement method, it is possible to evaluate the radiation directivity of the antenna and the transmission / reception performance for the entire space of the mobile terminal.

  However, for reception diversity and MIMO transmission multi-antennas with two or more antenna elements, it is necessary to consider the spatial correlation between the antennas in addition to the radiation directivity of each antenna and the transmission / reception performance for the entire space. There is. Therefore, it is necessary to evaluate the performance of the antenna and the mobile terminal in an environment simulating an actual multiwave environment.

Conventionally, as an antenna measurement system that simulates a multiwave environment, for example, there is an antenna measurement system described in Patent Document 1 (see, for example, Patent Document 1).
As shown in FIG. 20, this antenna measuring apparatus controls the amplitude and phase of radio waves radiated from a plurality of antennas 102a to 102g arranged at equal intervals on the circumference, so that these radio waves It controls the nature of the multi-wave environment constructed near the center. At this time, it is possible to evaluate the performance in the actual use environment by arranging the antenna to be measured 110 such as a diversity antenna near the center of the circle.
CTIA Test Plan for Mobile Station OTA Performance Revision 2.1 JP 2005-227213 A

  In the antenna evaluation apparatus of Patent Document 1, the number of signals that need to be controlled in amplitude and phase is the same as the total number of antennas 102a to 102g. For this reason, as shown in FIG. 21, the same number of attenuators 201a-207a and phase shifters 208a-214a as antennas 102a-102g are provided, and these attenuators 210a-207a and phase shifters 208a-214a The amplitude and phase were controlled for each of the antennas 102a to 102g. In this regard, it cannot be said that the antenna evaluation apparatus of Patent Document 1 has a simple configuration.

  An object of the present invention is to provide an antenna measurement system and method capable of simulating a multi-wave environment with a simpler configuration.

  An antenna measurement system according to the present invention includes a device under measurement, a plurality of antennas for measurement including a pair of antennas for measurement located on a circumference centered on the device under measurement and having a central angle of 45 ° or less, And a switching device that selects two or more measurement antennas to be used simultaneously from the antenna, and an amplitude and phase control device that outputs uncorrelated signals to the selected measurement antennas via the switching device.

  The antenna measurement method according to the present invention comprises two or more measurement antennas used simultaneously from a plurality of measurement antennas including a pair of measurement antennas located on a circumference centering on the device under test and having a central angle of 45 ° or less. And a switching step for outputting a signal uncorrelated to each selected measurement antenna via the switching device.

  By selecting a measurement antenna to be used simultaneously from a plurality of measurement antennas with the switching device, the number of signals that need to be controlled in amplitude and phase can be made smaller than the total number of measurement antennas. The signals supplied to the measurement antennas may be uncorrelated signals. Therefore, an antenna measurement system and method that can simulate a desired multiwave propagation environment can be configured more simply.

[First embodiment]
The antenna measurement system and method according to the first embodiment will be described with reference to FIG.
A device under test 1 which is a device to be measured by the antenna measurement system and method according to the present invention is a mobile terminal such as a mobile phone provided with two or more antenna elements. In this example, the device under measurement 1 is disposed on the turntable 2.

  The turntable 2 has a predetermined rotation axis, and can rotate the mounted one around the rotation axis. In this example, the rotation axis is perpendicular to the ground. Therefore, the turntable 2 can rotate the device under test 1 arranged on the turntable 2 in a horizontal plane. By using the turntable 2, antenna measurement at various angles can be facilitated.

  The plurality of measurement antennas 3 are arranged on a circumference centered on the device under measurement 1. For example, the distance between the device under test 1 and each measurement antenna 3 is 5 wavelengths. The plurality of measurement antennas 3 are arranged at substantially the same height as the device under measurement 1, that is, at substantially the same position as the device under measurement 1 in the direction perpendicular to the horizontal plane.

  In land mobile communication systems such as mobile phones, as shown in FIG. 2, the radio waves from the base station have the angle φ in the horizontal plane (xy plane) and the z-axis with the mobile terminal as the center of coordinates. The directions θ, the distribution, and the spread of the arriving wave depend on the environment around the terminal, that is, the arrangement of the peripheral scatterers. Therefore, in order to evaluate the performance of the mobile terminal in an actual propagation environment, it is necessary to flexibly consider these propagation environments. For this purpose, as illustrated in FIG. 1, a plurality of measurement antennas 3 are arranged around the device under measurement 1.

  The plurality of measurement antennas 3 include at least a pair of measurement antennas 3a and 3b having a central angle of 45 ° or less. The device under test 1 and the pair of measurement antennas 3a and 3b are respectively arranged at the vertices of an isosceles triangle. That is, the pair of measurement antennas 3a and 3b is arranged at the base angle position of the isosceles triangle when the device under test 1 is arranged at the apex point of the isosceles triangle. And the angle Θ of the apex angle of this isosceles triangle is 45 ° or less. In this example, not only the measurement antennas 3a and 3b but also the measurement antennas 3 are arranged so that each measurement antenna 3 forms a central angle of 45 ° or less with the measurement antennas adjacent to each other.

  The amplitude / phase control device 4 generates a plurality of uncorrelated signals and sends them to the switching device 5. Signals that are uncorrelated with each other need only be at least the number of two or more measurement antennas 3 that are used at the same time, and need not necessarily be the total number of measurement antennas 3. Here, the fact that the two signals are uncorrelated means that the correlation coefficient of the two signals is sufficiently close to zero.

  The switching device 5 selects two or more measurement antennas 3 to be used at the same time and supplies uncorrelated signals supplied from the amplitude / phase control device 4 to each of the selected measurement antennas 3. In this way, mutually uncorrelated signals generated by the amplitude phase control device 4 are supplied to the selected measurement antenna 3 via the switching device 5.

Hereinafter, it will be described in Examples 1 to 4 of the first embodiment that a desired multiwave environment can be simulated by the antenna measurement system and method of the first embodiment.
[Example 1]
First, let us consider simulating a cluster model having an angular spread AS equal to the central angle Θ with two measurement antennas 3a and 3b having a central angle Θ of 45 ° or less.

  For example, the amplitude / phase control device 4 generates two signals that are uncorrelated with each other and sends them to the switching device 5. The switching device 5 selects two measurement antennas 3a and 3b having a central angle Θ of 45 ° or less from among the plurality of measurement antennas 3, and two uncorrelated two signals are used for two measurements. The antennas 3a and 3b are supplied. The antenna measurement system in this state is shown in FIG. In FIG. 3, other measurement antennas 3 that are not used at the same time are omitted. In the antenna measurement system in this state, radio waves are radiated toward the device under test 1 from each of the two directions in which the measurement antennas are installed. Therefore, the characteristics are shown in FIG. It can be modeled with a two-wave model where the spread AS = center angle Θ.

By the way, as shown in FIG. 4, centering on the angular position rotated by an angle AoA counterclockwise from the broadside direction (x-axis direction of FIG. 4) of the array of antenna elements 1a and 1b of the device under test 1 Assume that radio waves arrive within the range of the angular spread AS. Radio waves within the range of this angular spread AS form clusters as a collection of elementary waves in an actual multiwave environment. This cluster can be modeled by the Laplace distribution P represented by the following formula or FIG. In the following equation, N ₀ is a normalization coefficient, and φ is an angle in the counterclockwise direction from the x axis in FIG.

  Here, assuming that the angular spread AS (= center angle Θ) in the two-wave model is equal to the angular spread AS in the Laplace distribution model, radio waves based on the respective models are radiated toward the device 1 to be measured. The received power of the device under test 1 and the correlation coefficient of the signals received by the two antenna elements 1a and 1b included in the device under test 1 are obtained by simulation and compared. When the received power and the correlation coefficient in the two-wave model are sufficiently close to the received power and the correlation coefficient in the Laplace distribution model, respectively, or the changes in the received power and the correlation coefficient in the two-wave model are the Laplace distribution model. It can be seen that the cluster model can be simulated by the two-wave model, in other words, by the antenna measurement system in the state of FIG.

  In FIG. 6, when the radio wave based on the two-wave model and the Laplace distribution model is radiated from the arrival direction AoA toward the device 1 to be measured, the received power of the device 1 to be measured and The simulation result about the correlation coefficient of the signal which antenna element 1a, 1b received is shown. Note that the range of the arrival direction AoA is 0 to 90 ° due to the symmetry of the coordinates. FIG. 6A shows a simulation result of angular spread AS = 20 ° ≦ 45 °, and FIG. 6B shows a simulation result of angular spread AS = 60 °> 45 °. As indicated by the display with arrows that bind the lines, the solid line indicates the received power and the dotted line indicates the correlation coefficient. The line with ● represents the simulation result of the two-wave model, and the line without ● represents the simulation result of the Laplace distribution model.

  FIG. 6 shows that when the angular spread AS = 20 ° and 45 ° or less, the received power and the correlation coefficient of the two-wave model and the Laplace distribution are in good agreement. On the other hand, when the angular spread AS = 60 ° and larger than 45 °, the received power and the correlation coefficient of the two-wave model and the Laplace distribution do not coincide with each other, and there is a difference.

  FIG. 7 shows the RMS (root mean square) error of the received power and the correlation coefficient when the angular spread AS is changed from 0 to 60 °. A broken line in FIG. 7 indicates a position having an angular spread of 45 °. FIG. 7A shows the RMS error of the received power of the two-wave model and the Laplace distribution model, and FIG. 7B shows the RMS error of the correlation coefficient of the two-wave model and the Laplace distribution model. ● The attached line is the RMS error when the distance between the two antenna elements 1a, 1b of the device under test 1 is 0.2 wavelength, and the attached line is the RMS error when the distance is 0.5 wavelength. Lines with ▲ indicate RMS errors when the interval is 1.0 wavelength.

  FIG. 7 shows that the RMS error of the received power and the RMS error of the correlation coefficient both increase as the angular spread AS increases. In addition, it can be seen that the RMS error of the received power and the RMS error of the correlation coefficient both increase as the distance between the antenna elements 1a and 1b increases. However, when the angular spread AS is 45 ° or less, the RMS error of the received power and the RMS error of the correlation coefficient can be reduced to 1 dB or less and 0.3 or less, which are errors that do not cause a practical problem, respectively. Recognize. The reason why it can be said that there is no practical problem will be described below with reference to FIG.

  FIG. 8A is a simulation result showing a change in the normalized MIMO transmission capacity when the received power is changed, and FIG. 8B is a change in the normalized MIMO transmission capacity when the correlation coefficient is changed. It is the simulation result which shows the mode. The normalized MIMO transmission capacity is obtained by standardizing each MIMO transmission capacity by the MIMO transmission capacity by dividing by a certain MIMO transmission capacity value. In FIG. 8A, the MIMO transmission capacity is standardized when the received power is 0 dB, and in FIG. 8B, it is standardized by the MIMO transmission capacity when the correlation coefficient is 0.0. The line with ● is the simulation result when the SNR is 20 dB, and the line with ■ is the simulation result when the SNR is 30 dB.

  For example, in FIG. 8A, even if the received power fluctuates from −1 dB to ± 1 dB, the normalized MIMO transmission capacity does not change by 0.1 or more. In addition, even if the correlation coefficient varies from 0.3 to ± 0.3 in FIG. 8B, the normalized MIMO transmission capacity does not change by 0.1 or more. Therefore, according to FIG. 8, in the case where the RMS error of the received power is 1 dB or less, the RMS error of the correlation coefficient is 0.3 or less, the normalized MIMO in any case of SNR = 20 dB and SNR = 30 dB. It can be seen that the transmission capacity can be evaluated with an accuracy of about 10%.

In general, it is known that the arrival distribution in the horizontal plane around the terminal in an actual propagation environment needs to consider not only a uniform distribution but also a cluster distribution biased in a specific direction (for example, see Reference 1). )
[Reference 1] A. Kuchar et al., IEEE Trans. AP., Vol. 48, no. 2, Feb. 2000.

  As described above, according to the antenna measurement system and method of Example 1 of the first embodiment, Laplace has two measurement antennas having a central angle Θ of 45 ° or less and an angular spread AS equal to the central angle Θ. A distribution model can be simulated. In other words, a cluster model having an angular spread AS of 45 ° or less can be simulated by the antenna measurement system and method of the first embodiment.

[Example 2]
Cluster model having at least three measurement antennas having a central angle of 45 ° or less formed by three measurement antennas adjacent to each other and having two 45 ° angular spread AS, that is, an angular spread AS up to 90 ° Think of simulating.

  For this purpose, the measurement antenna 3 is located on a circumference centered on the device under measurement 1 and has at least three measurement antennas 3a, 3b, whose central angles formed by the measurement antennas adjacent to each other are 45 ° or less. 3c is included. Then, the amplitude / phase control device 4 generates three signals that are uncorrelated with each other and sends them to the switching device 5. The switching device 5 selects at least three measurement antennas 3a, 3b, 3c having a central angle of 45 ° or less between adjacent measurement antennas from among the plurality of measurement antennas 3, and is uncorrelated with each other. These three signals are supplied to three measurement antennas 3a, 3b and 3c, respectively. The antenna measurement system in this state is shown in FIG. In FIG. 9, other measurement antennas 3, amplitude phase control devices 4, and switching devices 5 that are not used at the same time are omitted.

  In FIG. 10, when the radio wave based on the three-wave model and the Laplace distribution model is radiated from the arrival direction AoA toward the device 1 to be measured, The simulation result about the correlation coefficient of the signal which antenna element 1a, 1b received is shown. Note that the range of the arrival direction AoA is 0 to 90 ° due to the symmetry of the coordinates. In FIG. 10A, the angle formed by the measurement antennas 3a and 3b is 30 °, the angle formed by the measurement antennas 3b and 3c is 30 °, and the angular spread AS is 30 ° + 30 = 60 ° ≦ 90 °. It is a simulation result. In FIG. 10B, the angle formed by the measurement antennas 3a and 3b is 60 °, the angle formed by the measurement antennas 3b and 3c is 60 °, and the angular spread AS is 60 ° + 60 ° = 120 °> 90 °. This is a simulation result. As indicated by the display with arrows that bind the lines, the solid line indicates the received power and the dotted line indicates the correlation coefficient. The line with ● represents the simulation result of the three-wave model, and the line without ● represents the simulation result of the Laplace distribution model.

FIG. 10 shows that when the angular spread AS = 60 ° and 90 ° or less, the received power and the correlation coefficient of the three-wave model and the Laplace distribution model are in good agreement. On the other hand, when the angular spread AS = 120 ° and larger than 90 °, the received power and the correlation coefficient of the three-wave model and the Laplace distribution do not coincide with each other, and there is a difference.
In an actual multiwave propagation environment, it is known that the angular spread AS of the cluster arriving at the device under test 1 may be expected to be about 60 ° (for example, see Reference 2).
[Reference 2] 3GPP TR.25.996, “Spacial channel model for Multiple Input Multiple Output (MIMO) simulations”.

  As described above, with the antenna measurement system and method of Example 2 of the first embodiment, the three measurement antennas having a central angle Θ of 45 ° or less with the measurement antennas adjacent to each other, the angle of 90 ° or less. A cluster model having a spread AS can be simulated.

Example 3
Consider simulating a cluster model having two clusters having an angular spread AS of 45 ° using two pairs of measurement antennas having a central angle of 45 ° or less.

  Therefore, it is assumed that the measurement antenna 3 includes at least two pairs of measurement antennas having a central angle of 45 ° or less. Then, the amplitude / phase control device 4 generates four signals that are uncorrelated with each other and sends them to the switching device 5. The switching device 5 selects the measurement antennas 3a, 3b, 3c, and 3d that constitute two pairs of measurement antennas having a central angle of 45 ° or less, and each of four signals that are uncorrelated with each other is used for four measurements. The antennas 3a, 3b, 3c, and 3d are supplied. FIG. 11 shows the antenna measurement system in this state. In FIG. 11, other measurement antennas 3, amplitude phase control devices 4, and switching devices 5 that are not used at the same time are omitted.

  In FIG. 12, when the radio wave based on the 4-wave model and the Laplace distribution model is radiated from the arrival direction AoA toward the device under measurement 1, the received power of the device under measurement 1 and two The simulation result about the correlation coefficient of the signal which antenna element 1a, 1b received is shown. Note that the range of the arrival direction AoA is 0 to 90 ° due to the symmetry of the coordinates. FIG. 12A shows the case where the angle spread AS of each pair of measurement antennas is 20 °, that is, the angle formed by the measurement antennas 3a and 3b is 20 °, and the angle formed by the measurement antennas 3c and 3d. It is a simulation result in case that is 20 degrees. FIG. 12B shows the case where the angle spread AS of each pair of measurement antennas is 60 °, that is, the angle formed by the measurement antennas 3a and 3b is 60 °, and the angle formed by the measurement antennas 3c and 3d. It is a simulation result in case that is 60 degrees. As indicated by the display with arrows that bind the lines, the solid line indicates the received power and the dotted line indicates the correlation coefficient. The line with ● indicates the simulation result of the 4-wave model, and the line without ● indicates the simulation result of the Laplace distribution model.

  From FIG. 12, when the angular spread AS of each pair of measurement antennas is 20 ° and 45 ° or less, the received power and the correlation coefficient of the 4-wave model and the Laplace distribution model are in good agreement. I understand. On the other hand, when the angular spread AS of each pair of antennas for measurement is 60 ° and larger than 45 °, the received power and the correlation coefficient of the four-wave model and the Laplace distribution are not the same and a difference occurs. ing.

  As described above, using the antenna measurement system and method of Example 3 of the first embodiment, two measurement antenna pairs having a central angle of 45 ° or less are used, and two antennas having an angle spread AS of 45 ° are used. A cluster model with clusters can be simulated.

Example 4
Consider that a uniform distribution model is simulated by using at least eight measurement antennas 3 having the same center angle formed by adjacent measurement antennas. In this example, it is assumed that the number of measurement antennas 3 having the same center angle between the measurement antennas adjacent to each other is eight. That is, it is assumed that the central angle formed by the measurement antennas adjacent to each other is 45 °. A case where the number of measurement antennas 3 is nine or more can be configured in the same manner as in the case of eight, and thus the description thereof is omitted.

  It is assumed that the measurement antennas 3 are eight measurement antennas having the same center angle formed by the measurement antennas adjacent to each other. Then, the amplitude / phase control device 4 generates eight signals that are uncorrelated with each other and sends them to the switching device 5. The switching device 5 selects eight measurement antennas having the same center angle formed by adjacent measurement antennas, and supplies eight uncorrelated signals to the eight measurement antennas 3 respectively. An antenna measurement system in this state is shown in FIG. In FIG. 13, the amplitude and phase control device 4 and the switching device 5 are omitted.

  FIG. 14 shows the received power of the device under measurement 1 and the two antenna elements 1a and 1b provided in the device under measurement 1 when radio waves are radiated from the eight measurement antennas toward the device under measurement 1. The simulation result about the correlation coefficient of the received signal is shown. For comparison, a simulation result when radio waves are radiated from four measurement antennas having the same center angle between adjacent measurement antennas is indicated by a one-dot chain line, and the center angles formed by adjacent measurement antennas are equal. The simulation results when radio waves are radiated from the six measurement antennas are also shown by dotted lines. 14A shows a simulation result when the distance between the antenna elements 1a and 1b of the device under test 1 is 0.2 wavelength. FIG. 14B shows the result when the distance between the antenna elements 1a and 1b of the device under measurement 1 is 0. FIG. FIG. 14C shows a simulation result when the distance between the antenna elements 1a and 1b of the device under test 1 is 1.0 wavelength.

  Here, when the azimuth angle of the device under test 1 is changed from −180 ° to 180 °, the received power and the correlation coefficient take constant values, and when they do not change, it is evaluated that the distribution is uniform. be able to. Here, the azimuth angle of the device under measurement 1 means an angle around the rotation axis of the turntable 2 of the device under measurement 1.

  According to FIG. 14A, when the distance between the antenna elements 1a and 1b of the device under test 1 is 0.2 wavelengths, the number of antennas for measurement 3 is increased even if the azimuth angle of the device under test 1 is changed. It can be seen that the received power and the correlation coefficient do not change greatly. Further, according to FIG. 14B, when the distance between the antenna elements 1a and 1b of the device under test 1 is 0.5 wavelength, the number of measurement antennas 3 is 4, that is, the measurement antennas at 90 ° intervals. If the azimuth angle of the device under test 1 is changed, the received power and the correlation coefficient change greatly. Further, according to FIG. 14C, when the distance between the antenna elements 1a and 1b of the device under test 1 is 1.0 wavelength, the measurement is performed even when the number of measurement antennas 3 is six, that is, at 60 ° intervals. It can be seen that when the azimuth angle of the device under test 1 is changed, the received power and the correlation coefficient are greatly changed even when the antenna is disposed. On the other hand, when the number of measurement antennas 3 is 8, that is, when the measurement antennas are arranged at 45 ° intervals, the device under measurement is independent of the distance between the antenna elements 1a and 1b of the device under measurement 1. Even if the azimuth angle of 1 is changed, the received power and the correlation coefficient do not change or change significantly.

  As described above, with the antenna measurement system and method of Example 4 of the first embodiment, a uniform distribution model is obtained using at least eight measurement antennas 3 having the same center angle formed by adjacent measurement antennas. Can be simulated.

[Second Embodiment]
In the antenna measurement system of the second embodiment, as illustrated in FIG. 15, measurement is performed at each of two positions on the spherical surface centered on the device under test 1 and different in the vertical direction (= vertical direction). An antenna 3 is arranged. Only this point is different from the first embodiment, and the other points are the same as in the first embodiment.

  Assuming that two different positions in the vertical direction are the upper position and the lower position, respectively, in the example shown in FIG. 15, a plurality of measurement antennas 3 are disposed at the upper position, and a plurality of measurement antennas 3 are disposed at the lower position. Yes. The lower position is substantially the same as the position of the device under test 1 in the vertical direction. Each measurement antenna disposed at the upper position forms a central angle of 45 ° or less with any of the measurement antennas disposed at the lower position in a sphere centered on the device under measurement 1.

  Further, as illustrated in FIG. 16, one measurement antenna Tx1 may be disposed at the upper position, and two measurement antennas Tx2 and Tx3 may be disposed at the lower position. The two measurement antennas Tx2 and Tx3 form a central angle of 45 ° and correspond to the pair of measurement antennas 3a and 3b of the first embodiment. The measurement antenna Tx1 forms a central angle of 45 ° with each of the measurement antennas Tx2 and Tx3. The lower position is substantially the same as the position of the device under test 1 in the vertical direction. Note that the measurement antennas Tx1, Tx2, and Tx3 are the same as the measurement antenna 3. 17A shows a view of the antenna measurement system of FIG. 16 viewed from the z-axis direction, and FIG. 17B shows a view of the antenna measurement system of FIG. 16 viewed from the x-axis direction.

In general, the incoming wave distribution in the vertical plane around the terminal (the plane illustrated in FIG. 17B) is constant around a direction slightly deviated from the horizontal plane (the plane illustrated in FIG. 17A) in the elevation direction. It is known that the distribution has an angular spread AS (see, for example, Reference 3).
[Reference 3] K. Kalliola et al., IEEE Trans. VT., Vol. 51, no. 5, Sept. 2002.

  In this way, by arranging the measurement antennas at two different positions in the vertical direction, it is possible to simulate a cluster model that takes into account not only the horizontal angular spread but also the vertical angular spread. Thereby, the performance evaluation of the device under test 1 can be performed under conditions more faithful to the actual propagation environment.

[Third embodiment]
The antenna measurement system of the third embodiment will be described with reference to FIG.
The antenna measurement system of the third embodiment includes a pseudo base station device 6 that can communicate with the device under test 1 in order to simulate the actual environment in which the device under test 1 is used as faithfully as possible. The received signal quality information generated in step (1) is sent to the pseudo base station apparatus 6. That is, antenna measurement is performed in an environment where there is not only a downlink signal radio wave transmitted from the measurement antenna 3 to the device under test 1 but also an uplink signal radio wave transmitted from the device under test 1 to the pseudo base station apparatus 6. Do. Only this point is different from the first embodiment and the second embodiment, and the other points (for example, the points such as the arrangement of the measurement antenna 3) are the same, and thus redundant description is omitted.

  A server 7 that stores data such as voice, music, characters, images, and moving images is connected to the pseudo base station apparatus 6. The server 7 sends the accumulated data to the pseudo base station device 6. The pseudo base station apparatus 6 sends the data to the amplitude / phase control apparatus 4 as a downlink signal. The amplitude phase control device 4 converts the data into signals that are uncorrelated with each other, and sends the signals to a plurality of measurement antennas 3 that are selected by the switching device 5 and used simultaneously. The measurement antenna 3 radiates a radio wave corresponding to the supplied signal toward the device under measurement 1. When the device under measurement 1 receives a radio wave, a reception signal quality information generation unit (not shown) in the device under measurement 1 generates reception signal quality information for the radio wave. The device under measurement 1 transmits the generated received signal quality information to the pseudo base station apparatus 6 via the uplink radio line. The uplink radio line is an uplink used when the device under test 1 is actually used.

  The received signal quality information is information indicating the quality of the received signal. Received signal quality information includes received signal strength indicator (RSSI), received signal code power (RSCP), signal to noise ratio (SNR), signal to interference power ratio ( SIR: Signal to Interference Signal (SINR), Signal to Interference and Noise Ratio (SINR), Carrier to Noise Ratio (CNR), Carrier to Interference Power Ratio (CIR) Information including at least one of a ratio, a carrier to interference and noise ratio (CINR), and the like can be used.

  By acquiring the received signal quality information via the uplink radio line of the device under test 1, it is not necessary to modify the device under test 1 to acquire the received signal quality information, and the actual device under test is in an operating state. The characteristics of the device 1 can be evaluated. Further, by acquiring the received signal quality information via the uplink radio line of the device under test 1, the received signal quality information can be easily acquired.

  The received signal quality information reflects the influence of received power and correlation coefficient related to the characteristics of the communication antenna. The received signal quality information also reflects the influence of reception sensitivity and signal processing related to the characteristics of the wireless unit of the device under test 1 by using a mobile terminal that actually operates. Therefore, by using this received signal quality information, comprehensive radio performance evaluation of a mobile terminal including an antenna can be realized in an environment simulating an actual multiwave environment, and transmission characteristics can also be evaluated.

  The pseudo base station apparatus 6 may include an adaptive modulation unit 61 that selects an optimal modulation scheme and coding rate in accordance with the propagation environment from the measurement antenna 3 to the device under measurement 1. In this case, the device under measurement 1 includes an adaptive demodulation unit (not shown) corresponding to the adaptive modulation means of the pseudo base station device 6. As a result, it is possible to more faithfully simulate the multi-wave propagation environment generated by the actual pseudo base station apparatus 6 having a so-called adaptive modulation / demodulation function and the device under test 1.

  For example, when the received signal quality indicated by the received signal quality information acquired from the device under test 1 is good, the adaptive modulation unit 61 sets the coding rate to a high value using a modulation method having a large multi-value number, and When the received signal quality indicated by the information is poor, the coding rate is set to a low value using a modulation scheme with a small multi-level number. In order to determine the quality of the received signal quality, the pseudo base station apparatus 6 or the device under test 1 includes a communication speed measuring means for measuring the communication speed in the path from the server 7 to the device under test 1. It may be.

[Modifications, etc.]
As the device under measurement 1, a device that receives electromagnetic waves, such as a device other than a portable terminal or an antenna other than a multi-antenna, may be used.
Each measurement antenna 3 may include one or more radiating elements. For example, two radiating elements, an element that radiates vertical polarization and an element that radiates horizontal polarization, may be provided. As a result, it is possible to simulate a multi-wave environment in consideration of the so-called cross polarization power ratio. For example, the cross polarization power ratio is defined as vertical polarization power / horizontal polarization power. In order to show that each measurement antenna 3 may include two radiating elements, an element that radiates vertical polarization and an element that radiates horizontal polarization, each measurement antenna 3 is shown in each drawing. , Each of which is represented by a cross of two line segments corresponding to an element that radiates vertical polarization and an element that radiates horizontal polarization. However, this does not mean that each measurement antenna 3 must have two radiating elements. Each measurement antenna 3 may include only one radiating element.

The signals generated and output by the amplitude / phase control device 4 may be signals that are uncorrelated with each other and change Rayleigh, that is, fading signals. This makes it possible to simulate a fading environment that assumes an out-of-line environment where the line-of-sight condition is not established on the transmission side and the reception side.
Needless to say, other modifications are possible without departing from the spirit of the present invention.

The figure which illustrates the function structure of the antenna measurement system of 1st embodiment. The figure which shows the propagation environment around the to-be-measured apparatus 1. FIG. The figure which illustrates the condition of the 1st Example of 1st embodiment. The figure for demonstrating the concept of angular spread AS. (A) is a figure which illustrates a Laplace distribution model, (b) is a figure which illustrates a 2 wave model. The figure which shows the comparison of the fluctuation | variation of the reception power with respect to an arrival direction and a correlation coefficient about a 1st Example. The figure which shows the root mean square (RMS) error from the Laplace distribution model of a two-wave model. The figure which shows the influence which received power and a correlation coefficient have on MIMO transmission capacity. The figure which illustrates the condition of the 2nd Example of 1st embodiment. The figure which shows the comparison of the fluctuation | variation of the reception power with respect to an arrival direction and a correlation coefficient about 2nd Example. The figure which illustrates the condition of the 3rd Example of 1st embodiment. The figure which shows the comparison of the fluctuation | variation of the reception power with respect to an arrival direction and a correlation coefficient about a 3rd Example. The figure which illustrates the condition of the 4th example of a first embodiment. The figure which shows the comparison of the fluctuation | variation of the reception power with respect to an azimuth and a correlation coefficient about 4th Example. The figure which illustrates the function structure of the antenna measurement system of 2nd embodiment. The figure which illustrates the function structure of the antenna measurement system of 2nd embodiment. (A) is the figure which looked at FIG. 16 from the z-axis direction, (b) is the figure which looked at FIG. 16 from the x-axis direction. The figure which illustrates the function structure of the antenna measurement system of 3rd embodiment. The figure for demonstrating the radiation directivity measurement by a prior art. The figure which illustrates the function structure of the antenna measuring device by a prior art. The figure which illustrates the function structure of the antenna measuring device by a prior art.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Device to be measured 2 Turntable 3 Antenna for measurement 4 Amplitude / phase control device 5 Switching device 6 Pseudo base station device 61 Adaptive modulation unit 7 Server

Claims (10)

An adaptive demodulator that demodulates the received signal modulated according to the propagation environment, generates received signal quality information that is information representing the quality of the received signal, and transmits the received signal quality information to the pseudo-base via an uplink radio channel; A device under test to be transmitted to the station device ;
A plurality of measuring antenna including a pair of the measurement antenna forming a central angle with a 45 ° or less located on a circumference around the device under test,
A switching device for selecting two or more measurement antennas to be used simultaneously as one or more pairs from the measurement antenna;
Uncorrelated signal from each other in the measuring antenna for each said selected pair, the amplitude-phase control device for outputting via the switching device,
A pseudo base that includes an adaptive modulation unit that selects an optimal modulation scheme and coding rate according to a propagation environment from the measurement antenna to the device under test, and transmits predetermined data as a downlink signal to the amplitude phase control apparatus A station device;
Antenna measurement system, including. The antenna measurement system according to claim 1,
It further includes a turntable for rotating the device under measurement.
An antenna measurement system. The antenna measurement system according to claim 1 or 2,
The plurality of measurement antennas are at least three measurement antennas having a central angle of 45 ° or less formed by measurement antennas positioned on a circumference centered on the device under measurement and adjacent to each other.
An antenna measurement system. The antenna measurement system according to claim 1 or 2,
The plurality of measurement antennas include at least two pairs of measurement antennas located on a circumference centered on the device under measurement and having a central angle of 45 ° or less.
An antenna measurement system. The antenna measurement system according to claim 1 or 2,
The plurality of measurement antennas are at least eight measurement antennas having equal central angles formed by adjacent measurement antennas,
An antenna measurement system. The antenna measurement system according to claim 1 or 2,
The plurality of measurement antennas are located on a spherical surface centered on the device under measurement, and are arranged at two different positions in the vertical direction.
An antenna measurement system. The antenna measurement system according to claim 1 or 2,
The plurality of measurement antennas are located on a spherical surface centered on the device under measurement, and form a central angle of 45 ° or less with each of the measurement antennas constituting the measurement antenna pair on the spherical surface. Further including a measurement antenna,
An antenna measurement system. The antenna measurement system according to any one of claims 1 to 7,
The signal is, you Rayleigh change
An antenna measurement system. The antenna measurement system according to any one of claims 1 to 8,
Each of the measurement antennas includes an element that radiates vertical polarization and an element that radiates horizontal polarization.
An antenna measurement system. Demodulate the received signal modulated according to the propagation environment, generate received signal quality information that is information indicating the quality of the received signal, and transmit the received signal quality information to the pseudo base station apparatus via the uplink radio channel The device under test step;
Two or more measurement antennas used at the same time from a plurality of measuring antenna as one or more pairs comprising pairs of measuring antenna for forming a central angle located on the circumference of less than 45 ° around the DUT A switching step to select,
Uncorrelated signal from each other in the measuring antenna for each said selected pair, and the amplitude phase control step of outputting through the switching device,
A pseudo base station step of selecting an optimal modulation scheme and coding rate according to a propagation environment from the measurement antenna to the device under test, and transmitting predetermined data to the amplitude phase control apparatus as a downlink signal;
Antenna measurement method, including.

Images