JP6209576B2 - Mobile terminal test apparatus and downlink signal phase adjustment method thereof - Google Patents

Description

  The present invention relates to an apparatus for testing a mobile terminal of MIMO (Multi Input Multi Output) system, and in particular, for aligning the phases of downlink (hereinafter referred to as DL) signals output from a plurality of antennas on the test apparatus side. Regarding technology.

  As a method for testing a mobile terminal such as a mobile phone or a smartphone in a wireless connection environment close to a real environment, there is a test using an OTA (Over The Air) environment. In this OTA environment, an antenna of a test apparatus and a mobile terminal to be tested are generally installed in a metal case (chamber) that shields external noise, and the test apparatus and metal case provided outside the metal case. The internal antenna is cable-connected to perform communication necessary for the test between the test apparatus and the mobile terminal.

  When performing a MIMO system test in such an OTA environment, the test apparatus side uses a plurality of series of DL signals that are orthogonally modulated with a baseband test signal and frequency-converted to several hundred MHz to several GHz. However, if the phase of each local signal used for orthogonal modulation processing or frequency conversion processing is not in phase, the phase of the DL signal supplied to each antenna will be shifted. Moreover, since the phase of the local signal for frequency conversion processing changes randomly not only at the time of starting the apparatus but also every time the DL frequency is switched, the phase difference of the DL signal supplied to each antenna also changes randomly. become.

  Thus, when the phase of the DL signal supplied to each antenna is shifted and the phase difference is changed randomly, the reproducibility of the measurement for the mobile terminal is lowered. For example, problems such as the measurement result of the reception throughput of the MIMO scheme in the OTA environment becoming unstable and the reception power on the mobile terminal side fluctuate.

  For this reason, when performing a test of the MIMO system, it is necessary to perform a process of matching the phase of the DL signal supplied to each antenna in advance before the test.

  Conventionally, the following method has been adopted as the phase matching process. That is, a plurality of DL signals to be supplied to each antenna are unmodulated carrier signals, of which a specific series of carrier signals is a reference signal and another series of carrier signals is an adjusted signal, and the reference signal and one adjusted signal These two signals are set to be output, and the phase of the signal to be adjusted is rotated while detecting the intensity of the combined signal of the two signals.

  Here, if the phase of the signal to be adjusted matches the reference signal, the intensity of the combined signal is maximized as shown in FIG. 8A, and if the phase is shifted by 180 degrees, the intensity of the combined signal is shown in FIG. Is theoretically 0 (actually the minimum). In general, the amount of phase shift when the strength falls to 0 (minimum) is more accurately obtained than the amount of phase shift when the strength of the synthesized signal is maximum. The amount obtained by adding 180 degrees to the amount is assumed to be a phase shift amount necessary for one signal to be adjusted to be phase-synchronized with the reference signal. The phase change of the signal to be adjusted can be realized by a phase shift process for the signal to be adjusted itself, a phase shift process for a local signal used for the frequency conversion process, or the like.

  In the case of a 2 × 2 MIMO system, there are two antennas on the transmission side, so the phase adjustment is completed by the above processing, but when there are three or more antennas, another signal to be adjusted and a reference By performing the same processing on the signal, the phases of the carrier signals of all the sequences can be matched with the reference signal. From this state, the mobile terminal uses the DL signal modulated by the modulation signal used for communication. You can start the test.

  An example of an apparatus for testing a MIMO mobile terminal is disclosed in Patent Document 1, for example.

JP 2014-158206 A

  However, in the phase matching method described above, it is necessary to detect the amount of phase shift that minimizes the intensity of the combined signal of the reference signal and the signal to be adjusted with a predetermined resolution. For example, when detecting with a single resolution, The process of measuring the power by changing the phase once is necessary to perform 360 times, which is inefficient.

  In particular, when performing a DL frequency handover or the like in a call connection test for a mobile terminal, the connection may be disconnected if phase adjustment is not completed within a few milliseconds. I can't do it. The phase adjustment needs to be performed every time the DL frequency is changed during the test. In the case of a test in which the DL frequency is frequently changed, the phase adjustment is performed each time, and the time required for the entire test is increased. It will be very long.

  The present invention solves the above-described problem, and a mobile terminal test apparatus capable of quickly matching the phases of DL signals supplied to a plurality of antennas during a MIMO mobile terminal test and its downlink signal phase The purpose is to provide an adjustment method.

In order to achieve the above object, a mobile terminal test apparatus according to claim 1 of the present invention comprises:
Baseband signal generation means (21) for outputting a plurality of baseband signals for terminal testing;
DC signal generating means (22) for outputting a baseband constant DC signal in a plurality of series;
A signal selection switch (23) for selectively outputting either a baseband signal output by the baseband signal generation means or a DC signal output by the DC signal generation means;
The output signal from the signal selection switch is subjected to arithmetic processing using characteristic coefficients including gain and phase information of a plurality of transmission paths assumed between MIMO transmission / reception antennas, and a plurality of series of modulation signals are obtained. Transmission path information giving means (25) for outputting;
A transmission unit (30) that outputs a plurality of sequences of downlink signals that are orthogonally modulated by the plurality of sequences of modulation signals and are frequency-converted to a frequency band used for communication by the mobile terminal to be tested;
A plurality of transmission antennas (45 _{1 to} 45 _N ) that respectively receive a plurality of series of downlink signals output from the transmission unit;
A receiving antenna (46) for receiving an uplink signal output by the mobile terminal with respect to radio waves output from the transmitting antenna;
A receiver (60) capable of receiving and demodulating the uplink signal and the downlink signal;
A reception signal changeover switch (40, 40 ', 41) for selectively inputting either the uplink signal or the downlink signal to the reception unit;
In the test mode for performing a test by communication with the mobile terminal, the baseband signal is output from the signal selection switch, and in the phase adjustment mode for performing phase alignment of the downlink signals of the plurality of series, Modulation switching control means (81) for outputting the DC signal from a signal selection switch;
Control at least the reception signal changeover switch, and in the test mode, the uplink signal output from the mobile terminal is input to the reception unit and demodulated. In the phase adjustment mode, the uplink signal is converted to the uplink signal. Instead, received signal switching control means (83) for selectively inputting the downlink signals of the plurality of sequences one by one to the receiving unit and demodulating them,
Phase detection means (84) for detecting a phase of a signal sequentially demodulated by the receiving unit in the phase adjustment mode;
From the phase sequentially detected by the phase detection means, a phase shift amount necessary for matching all phases of the downlink signals of the plurality of series output from the transmission unit is obtained, and the characteristic coefficient of the transmission path information giving means is obtained. And phase correction means (85) for correcting the phase information by the amount of phase shift.

A mobile terminal test apparatus according to claim 2 of the present invention is the mobile terminal test apparatus according to claim 1,
A multiplexer (50) for multiplexing a plurality of sequences of downlink signals output by the transmitter;
The reception signal changeover switch is configured to select one of the output of the reception antenna and the output of the multiplexer and give it to the reception unit,
The received signal switching control means includes
In the test mode, the reception signal changeover switch causes the output of the reception antenna to be input to the reception unit, and in the phase adjustment mode, the reception signal changeover switch outputs the output of the multiplexer to the reception unit. The gain used for one series of modulation signals is set to a predetermined value other than 0 and the gain used for the other series of modulation signals among the gains of the characteristic coefficients of the transmission path information giving means. By setting it to 0, one series of downlink signals is selectively given to the multiplexer.

A mobile terminal test apparatus according to claim 3 of the present invention is the mobile terminal test apparatus according to claim 1,
The reception signal changeover switch is configured to selectively output any one of a plurality of series of downlink signals output from the transmission unit and the output of the reception antenna,
The received signal switching control means includes
In the test mode, the reception signal change-over switch causes the output of the reception antenna to be input to the receiving unit, and in the phase adjustment mode, the reception signal change-over switch receives the plurality of sequences of downlink signals as one sequence. It is characterized in that the receiving unit inputs each one.

In addition, the downlink signal phase adjustment method of the mobile terminal test apparatus of the present invention,
Performs arithmetic processing using characteristic coefficients including gain and phase information of multiple transmission paths assumed between MIMO transmission and reception antennas for a fixed baseband DC signal, and outputs multiple series of modulation signals Performing step (S11);
Outputting a plurality of sequences of downlink signals each orthogonally modulated with the plurality of modulation signals and frequency-converted to a frequency band used for communication by the mobile terminal to be tested (S11);
Selectively receiving and demodulating the plurality of downlink signals one by one and detecting the phase thereof (S12 to S16);
Obtaining a phase shift amount necessary to match all phases of the plurality of downlink signals from the detected phase, and correcting phase information of the characteristic coefficient by the phase shift amount (S17). It is characterized by that.

  As described above, in the present invention, in the phase adjustment mode, a plurality of DL (downlink) signals that are orthogonally modulated and frequency-converted with a modulation signal based on a constant DC signal are received and demodulated one by one. The phase is detected, the phase shift amount necessary for the phases of the downlink signals of multiple sequences to be matched is obtained from the phase, and the phase information of the transmission path used for calculating the modulation signal is corrected by the amount of phase shift. ing.

  For this reason, it is only necessary to select a downlink signal and detect the phase for a plurality of sequences, and phase adjustment can be completed in a much shorter time than in the past.

  In particular, even when performing a DL frequency handover or the like, the phase adjustment can be completed in a time much shorter than several milliseconds, and there is no fear of disconnection. Further, even when the DL frequency is frequently changed during the test, the phase adjustment is completed in a short time, so that the influence on the entire test is small and the test can be performed efficiently.

Configuration diagram of an embodiment of the present invention The figure which shows a part of structure of the transmission part of embodiment. The figure which shows another structural example of a part of embodiment The flowchart which shows an example of the whole process sequence of embodiment The figure which shows another structural example of a part of embodiment The flowchart which shows an example of the process sequence of the phase adjustment of embodiment Signal phase diagram for explaining the operation of the embodiment The figure for demonstrating the conventional phase adjustment method

Hereinafter, embodiments of the present invention will be described with reference to the drawings.
FIG. 1 shows a configuration of a MIMO mobile terminal test apparatus 20 (hereinafter simply referred to as a test apparatus) to which the present invention is applied. Here, a test apparatus corresponding to a MIMO system such as 2 × 2, 4 × 4, 8 × 8, etc., in which the number of transmission antennas on the base station side and the number of reception antennas on the terminal side are the same will be described. The present invention can also be applied to a MIMO system such as 4 × 2.

  As will be described later, the test apparatus 20 has two modes: a test mode for performing various tests by communicating with a mobile terminal to be tested, and a phase adjustment mode for performing phase alignment of DL signals used for the test. It has an operation mode.

  The baseband signal generation means 21 generates and outputs a plurality (N) series of baseband signals Sb1 to SbN used for communication with the mobile terminal. The baseband signals Sb1 to SbN are signals having a predetermined band corresponding to the radio access scheme OFDMA of the LTE mobile terminal to which the MIMO scheme is applied and the radio access scheme W-CDMA of the 3G mobile terminal. Each baseband signal is assumed to be composed of a signal sequence of digital data of I component and Q component whose phases are orthogonal to each other.

  The DC signal generating means 22 outputs the same baseband DC signals Sd1 to SdN in N series. Here, the same DC signal is invariable when one of the I component and Q component (for example, I component) which is an element of the baseband signal is a predetermined value (for example, 1) other than 0, and the other (for example, Q component). Is composed of a digital data sequence that is 0 and unchanged.

  The signal selection switch 23 receives the N-sequence baseband signals Sb1 to SbN and the N-sequence DC signals Sd1 to SdN and selectively outputs one of the signals. The signal selection switch 23 is controlled by a control unit 80, which will be described later, and outputs N-sequence baseband signals Sb1 to SbN in the test mode, and N-sequence DC signals Sd1 to SdN in the phase adjustment mode. Is output.

  The transmission path information assigning means 25 is a MIMO antenna having N transmission base antennas N and terminal reception antennas N for N-sequence signals S * 1 to S * N output from the signal selection switch 23. Perform the following arithmetic processing using characteristic coefficients H (1,1) to H (N, N) including information on gain and phase (delay) of multiple (N × N) transmission paths assumed in between N series of modulation signals Sm1 to SmN are output. It is assumed that the N series of modulation signals Sm1 to SmN are also composed of a signal sequence of digital data of I component and Q component, as described above.

  For example, in the 2 × 2 (N = 2) MIMO scheme, four transmission paths are assumed between two transmission antennas and two reception antennas, and the characteristic coefficient H (1,1) of the four transmission paths is assumed. ~ H (2,2) is defined as follows.

H (1,1) = G ₁ · e ^jθ1
H (1,2) = G ₂ · e ^jθ2
H (2,1) = G ₃ · e ^jθ3
H (2,2) = G ₄ · e ^jθ4
Here, G _{1 to} G ₄ are gains of the respective transmission lines, and θ _{1 to} θ ₄ are phases (delays) of the respective transmission lines.

  Assuming that the two series of input signals are S * 1 and S * 2, the following calculation is performed to obtain two series of modulation signals Sm1 and Sm2.

Sm1 ＝ H (1,1) ・ S * 1 + H (2,1) ・ S * 2
Sm2 ＝ H (1,2) ・ S * 1 + H (2,2) ・ S * 2

  The transmitting unit 30 performs orthogonal modulation with the I and Q components of the N-sequence modulation signals Sm1 to SmN and frequency-converts the DL signals St1 to StN in the frequency band used for communication by the mobile terminal to be tested. Is output.

  As shown in part of FIG. 2 (a), the configuration of the transmitter 30 is such that the Ik and Qk components of the kth modulation signal Smk are converted into analog signals Ik ′ and Qk ′ by the D / A converter 31k. A conversion method (direct conversion method) that converts the signal into a DL signal Stk by a frequency conversion unit 32k that also functions as an orthogonal modulation function, and a k-th modulation signal Smk as shown in part of FIG. Ik and Qk components are converted to analog signals Ik ′ and Qk ′ by a D / A converter 31k, and converted to an intermediate frequency band signal Sik by a quadrature modulator 33k, which is a simple heterodyne type mixer with one mixer. Any method of converting to the DL signal Stk by the frequency converter 34k may be used.

  Here, as described above, the local signal generators 35k and 35k ′ that supply the local signals to the frequency conversion units 32k and 34k are not common in each series so that they can be used for various tests, and thus have no phase. When the MIMO system test using the same transmission frequency is performed, the phase difference affects the reception result of the mobile terminal, thereby reducing the reproducibility of the test result. Note that, as shown in FIG. 2B, for the frequency conversion to the intermediate frequency band by the quadrature modulator 33k, a common local signal generator 36 can be used in each series, and the frequency of the local signal is usually Since it is invariant, the phase difference between DL signals is not affected.

The DL signals St1 to StN output from the transmission unit 30 are input to the reception signal changeover switch 40. The reception signal changeover switch 40 is controlled by the control unit 80. In the test mode, the DL signal St1 to StN is input to the _N transmission antennas 45 _{1 to} 45 _N and the uplink transmitted from the mobile terminal 1 is transmitted. A receiving antenna 46 for receiving a (UL) signal is connected to a receiving unit 60 described later. In the phase adjustment mode, the DL signals St1 to StN are input to the multiplexer 50, and the output is input to the receiving unit 60.

Here, it is assumed that the transmission antennas 45 _{1 to} 45 _N and the reception antenna 46 are accommodated together with the mobile terminal 1 to be tested in the metal case (chamber) 55 that forms the OTA environment described above.

Here, although the receiving antenna 46 is shown independently of the transmitting antennas 45 _{1 to} 45 _N , one of the transmitting antennas may be used for both transmission and reception. In this case, one series of DL signals output from the transmission unit 30 is input to the antenna for both transmission and reception via the circulator, and the UL signal received by the antenna is received via the circulator and the reception signal changeover switch 40. 60.

Further, the electrical lengths of the signal paths from the transmission unit 30 to the reception signal changeover switch 40 switch contact are equal, and the electrical lengths of the signal paths from the switch contact of the reception signal changeover switch 40 to the transmission antennas 45 _{1 to} 45 _N are also equal. The electrical lengths of the signal paths from the switch contact of the reception signal changeover switch 40 to the multiplexer 50 are also equal.

In this embodiment, the reception signal changeover switch 40 is configured to distribute the DL signals St1 to StN to one of the N transmission antennas 45 _{1 to} 45 _N and the multiplexer 50. As shown in FIG. 3, the DL signals St1 to StN may be provided to both of the _N transmission antennas 45 _{1 to} 45 _N and the multiplexer 50 at the same time. However, even in this case, it is necessary to select the output of the reception antenna 46 and the output of the multiplexer 50 by the reception signal changeover switch 40 '.

  The receiving unit 60 performs frequency conversion processing and orthogonal demodulation processing on the input signal Sr, and outputs a baseband demodulated signal Sdet. As for the configuration of the receiving unit 60, as in the transmitting unit 30, the direct conversion method in which the frequency conversion process and the orthogonal demodulation process are performed by one local signal, and the input signal is converted into the intermediate frequency band by the frequency conversion process. In any method, the I component and the Q component of the demodulated signal Sdet obtained by the orthogonal demodulation process are converted into a digital data signal sequence and output. Note that the reception frequency (local signal frequency) of the reception unit 60 is controlled by the control unit 80 together with the frequency of the DL signal output from the transmission unit 30, and not only the UL frequency used in the terminal test, but also the DL frequency. It is possible to receive and demodulate a signal having a frequency equal to the frequency.

  The demodulated signal Sdet from the receiving unit 60 is input to the control unit 80. The control unit 80 performs signal processing and the like necessary for control and testing of the entire test apparatus 20. The control unit 80 is configured by a computer including a CPU, a ROM, a RAM, and the like in hardware. In accordance with the input information, control of hardware inside the apparatus, various processing and analysis on the demodulated signal, etc. are performed, and necessary information such as test results is displayed on the display unit 92.

  Since the functions related to the terminal test of the control unit 80 are diverse, here, a test mode in which various tests for a mobile terminal to be tested are set in advance or individually, and a DL signal at the time of the MIMO system test is performed. The transition process to the phase adjustment mode for adjusting the phase and the function of the phase adjustment mode will be described.

  FIG. 4 is a flowchart showing an outline of the processing procedure of the entire apparatus. First, as preparation for performing the test, the process proceeds to the phase adjustment mode to perform the phase adjustment of the DL signal (S1), and then the test object. A call connection process with the mobile terminal 1 is performed (S2), and the test mode is entered (S3). When the DL frequency is changed during this test mode (S4), the phase adjustment mode is again entered (S5), the phase adjustment process for the new DL frequency is performed, and then the test mode (S3) is entered. When all the tests are completed (S6), the test results are displayed (S7).

Next, processing in the phase adjustment mode by the control unit 80 will be described.
As shown in FIG. 1, the control unit 80 includes modulation switching control means 81, received signal switching control means 83, phase detection means 84, and phase correction means 85 as functions necessary for performing the phase adjustment mode. Is provided.

  The modulation switching control means 81 outputs N series baseband signals Sb1 to SbN from the signal selection switch 23 in the test mode, and outputs N series DC signals Sd1 to SdN from the signal selection switch 23 in the phase adjustment mode. Output.

  In the test mode, the received signal switching control means 83 inputs the UL signal output from the mobile terminal to the receiving unit 60 and demodulates it. In the phase adjustment mode, the received signal switching control means 83 replaces the UL signal from the terminal side with N series DL signals St1 to StN are selectively input to the receiving unit 60 one by one and demodulated.

  Specifically, this control is performed by switching control of gain information of the characteristic coefficient used for calculation by the transmission path information adding unit 25 and switching control of the reception signal switch 40.

That is, in the test mode, the DL signals St1 to StN output from the transmission unit 30 are input to the transmission antennas 45 _{1 to} 45 _N, and the output (UL signal) of the reception antenna 46 is input to the reception unit 60. The reception signal changeover switch 40 is switched so that communication with the mobile terminal 1 is possible.

  Further, in the phase adjustment mode, the DL signal St1 to StN output from the transmission unit 30 is input to the multiplexer 50, and the reception signal changeover switch 40 is switched so that the output is input to the reception unit 60. The reception frequency of the unit 60 is temporarily changed from the regular UL frequency to the DL frequency. Furthermore, the gain value of the transmission path information adding unit 25 is switched so that the DL signals St1 to StN are input to the receiving unit 60 for each series.

  In addition to the above, the configuration for switching the received signal includes a signal path from the transmission path information adding means 25 to the transmission unit 30, a signal path from the transmission unit 30 to the reception signal switching switch 40, or a reception signal switching switch. A configuration may be adopted in which a switch is inserted for each signal series in any of the signal paths from 40 to the multiplexer 50 and DL signals are input to the receiving unit 60 for each series by controlling the opening and closing thereof. .

  Further, as shown in FIG. 5, instead of the reception signal changeover switch 40 and the multiplexer 50, an N + 1: 1 reception signal changeover switch 41 is provided, and this is switched by the reception signal changeover control means 83 '. The DL signal for each series and the output of the receiving antenna 46 may be selectively input to the receiving unit 60. As described above, in the configuration in which the DL signal itself is opened and closed by the switch and the DL signal is input to the receiving unit 60 one by one, it is not necessary to switch the gain of the characteristic coefficient of the transmission path used for the modulation signal. It is.

In the phase adjustment mode, the phase detector 84 receives the demodulated signal Sdet sequentially output from the receiving unit 60 that receives the DL signal for each series, and sequentially detects the phases φ _{1 to} φ _N. Further, the phase correction unit 85 uses the phase shift amount necessary for matching all the phases of the N series DL signals output from the transmission unit 30 from the phases φ _{1 to} φ _N sequentially detected by the phase detection unit 84. And the phases θ _{1 to} θ _{N · N} of the transmission path information are corrected by the amount of phase shift.

  FIG. 6 is a flowchart showing a processing procedure when the control unit 80 is in the phase adjustment mode. Hereinafter, the operation of the test apparatus 20 will be described based on this flowchart.

Here, as shown in FIG. 7A, the N series DC signals Sd1 to SdN are data of Q = 0 and I = 1, and gains G _{1 to} G in the transmission path information adding unit 25 are previously set. _It is assumed that _{N · N} is an equal value (for example, 1) and the phases θ _{1 to} θ _{N · N} are also initially set to a specified value (for example, 0).

  When shifting to the phase adjustment mode, first, the signal selection switch 23 is switched so as to select the DC signals Sd1 to SdN, and the reception signal switching switch 40 is switched to the multiplexer 50 side to output the multiplexer 50. The signal is input to the receiving unit 60, and the reception frequency of the receiving unit 60 is changed from a regular UL frequency used for the terminal test to a frequency equal to the DL frequency (S11).

Then, a variable i that designates a DL signal sequence is initialized to 1, and the characteristic coefficient of the transmission path included in the modulation signal of the sequence, when N = 2, H (1,1), H (2, The gains G ₁ and G _{3 of} 1) are set to positive values other than 0, for example, 1 and other gains are set to 0 (S12, S13).

  When N = 2, the magnitude and phase of the input DC signals Sd1 and Sd2 are the same and the characteristic coefficients H (1,1) and H (2,1) applied to them are the same. Sm1 is twice Sd1 × H (1,1), and the DC and coefficient phases are both zero. Therefore, the DL signal modulated by the modulation signal Sm1 is shifted by the phase of the local signal used for frequency conversion processing (including orthogonal modulation processing) performed on the first modulation signal in the transmission unit 30. A phase will appear.

Modulation signal Sm2 for the second series, characteristic coefficient H (1, 2), because the gain of _{H (2,2) G 2, G} 4 is 0, Sm2 = 0, and the the DL signal is not output .

  Thus, one series of DL signals selectively output is input to the reception unit 60 via the reception signal changeover switch 40 and the multiplexer 50. Here, since the reception frequency of the receiving unit 60 is temporarily matched with the DL frequency, the input DL signal is correctly received and demodulated.

Phase phi ₁ of the demodulated signal Sdet1 is detected by the phase detecting means 84 of the control unit 80 (S14). As described above, the original modulation signal is a direct current of Q = 0 and I = 1 and has a phase of 0. However, due to the phase shift by the transmission unit 30 and the reception unit 60, for example, as shown in FIG. in, which is in a different phase φ ₁ of the non-zero. The phase detector 84 calculates the phase φ ₁ from the I component and Q component of the demodulated signal of the receiving unit 60. The phase φ ₁ includes a phase shift φt1 due to the frequency conversion process of the first sequence in the transmission unit 30 and a phase shift φr in the frequency conversion process of the reception unit 60. The phase shift φr in the conversion process is common regardless of the DL signal sequence.

The detected phase Fai ₁ is stored in a memory, the variable i is updated to the next value 2, the process returns to S13, the same processing is performed for the second series (S15, S16). For example, when N = 2, the gains G ₂ and G _{4 of} H (1,2) and H (2,2) are set to positive values other than 0, for example, 1 and other gains are set to 0 and 2 The modulation signal Sm2 of the first series is twice Sd1 × H (1,2), and the modulation signal Sm2 of the first series is zero.

  Accordingly, only the DL signal modulated by the second series of modulation signal Sm2 is output, and the DL signal is transmitted to the frequency modulated on the second modulation signal in the transmitter 30. A phase shift due to the phase of the local signal used for the conversion process (including quadrature modulation process) appears and is input to the reception unit 60 via the reception signal changeover switch 40 and the multiplexer 50, and the phase shift by the reception unit 60 is changed. In addition, it will be demodulated.

Similarly to the above, the phase φ ₂ of the DL signal of the second sequence is detected. In this phase φ ₂ , the phase shift φt 2 due to the frequency conversion processing of the second sequence by the transmitting unit 30 and the phase of the receiving unit 60 A common phase shift φr in the frequency conversion process is included.

If the phase phi ₂ of the second demodulated signal of the DL signal sequence Sdet2 it is assumed that the obtained, for example, as in FIG. 7 (c), the phase phi _1, phi ₂ of the difference [Delta] [phi (1, 2), the transmission unit This is due to the difference in the amount of phase shift in frequency conversion processing (including quadrature modulation processing) individually performed for each of the 30 signal sequences. Therefore, by adjusting so that this difference is eliminated, the phases of all DL signals in the reference state can be matched.

In the same manner, a demand phase phi ₁ to [phi] _N for all DL signal, prompts the required phase shift φh1~φhN To meet these reference values (e.g. 0), the transmission path information adding unit Each phase θ _{1 to} θ _{N · N of} 25 characteristic coefficients H (1,1) to H (N, N) is corrected by the amount of each phase shift (S17).

That is, when the initial values of the phases θ _{1 to} θ _{N · N} are 0 and N = 2, the two characteristic coefficients H (1 included in the modulation signal Sm1 that modulates the first series of DL signals , 1) and H (2,1) phase θ ₁ , θ ₃ are changed from the initial value 0 to the phase shift amount φh1, and the modulation signal Sm2 that modulates the second series of DL signals is obtained. The values of the phases θ ₂ and θ ₄ of the two characteristic coefficients H (1,2) and H (2,2) included are changed from the initial value 0 to the phase shift amount φh2.

The reference value is arbitrary, and when the reference value is 0 as described above, the amount of phase shift required for correction is
φh1 = -φ ₁
φh2 = -φ ₂
…………
φhN = -φ _N
It becomes.

If the reference value is, for example, the phase φ ₁ obtained for the first series, the amount of phase shift necessary for correction is
φh1 = 0
φh2 = φ ₂ −φ ₁
…………
φhN = φ _N −φ ₁
It becomes. Further, if the initial value of each of the phases θ _{1 to} θ _{N · N} is a value A other than 0, the initial value A may be changed and set to (phase shift amount + A).

  In this way, after the phases in the reference state of the DL signals of each series are matched, an N series baseband signal is output from the signal selection switch 23, the reception signal changeover switch 40 is connected to the antenna side, By returning the reception frequency of the reception unit 60 to the regular UL frequency (S18), the test mode can be entered.

  As described above, in the test mode, call connection processing is performed with the mobile terminal 1 and various tests are performed. When the DL frequency is changed during the test, The phase adjustment process is performed again at the DL frequency by shifting to the phase adjustment mode.

  As described above, the phase adjustment process for the DL signal of the test apparatus 20 sequentially detects the phase of the DL signal modulated by the DC signal, and is given by the transmission path information giving means 25 so that the phases are equal. The phase is corrected, and it can be completed at a very high speed by only switching the signal series and the phase detection process.

  For this reason, even when a DL frequency handover or the like is performed, the phase adjustment can be completed in a time much shorter than several milliseconds, and there is no fear of disconnection. Further, even when the DL frequency is frequently changed during the test, the phase adjustment is completed in a short time, so that the influence on the entire test is small and the test can be performed efficiently.

  In this embodiment, as a means for correcting the phase, a method of correcting the phase value of the characteristic coefficient of the transmission path information adding means 25 is adopted, and the phase of the DL signal is changed only by changing the numerical value used in the digital calculation. Therefore, it is not necessary to perform phase control on the local signal or the like of the transmission unit 30 that handles an extremely high frequency, and can be realized at low cost.

  In the above description of the operation, the phase of all DL signals is detected and then corrected. However, the phase of one DL signal is detected so that the detected phase becomes the reference value. It may be a procedure for detecting the phase of the next DL signal after correction.

DESCRIPTION OF SYMBOLS 1 ... Mobile terminal, 20 ... Mobile terminal test apparatus, 21 ... Baseband signal generation means, 22 ... DC signal generation means, 23 ... Signal selection switch, 25 ... Transmission path information provision means, 30 ...... transmitting section, 40, 40 ', 41 ...... received signal changeover _switch, 45 1 to 45 _N ...... transmitting antenna, 46 ...... receiving antenna, 50 ...... multiplexer, 55 ...... metal case, 60 ...... Receiving unit, 80... Control unit, 81... Modulation switching control unit, 83, 83 ′ received signal switching control unit, 84 …… phase detection unit, 85 …… phase correction unit, 91 …… operation unit, 92 ...... Display section

Claims (4)

Baseband signal generation means (21) for outputting a plurality of baseband signals for terminal testing;
DC signal generating means (22) for outputting a baseband constant DC signal in a plurality of series;
A signal selection switch (23) for selectively outputting either a baseband signal output by the baseband signal generation means or a DC signal output by the DC signal generation means;
The output signal from the signal selection switch is subjected to arithmetic processing using characteristic coefficients including gain and phase information of a plurality of transmission paths assumed between MIMO transmission / reception antennas, and a plurality of series of modulation signals are obtained. Transmission path information giving means (25) for outputting;
A transmission unit (30) that outputs a plurality of sequences of downlink signals that are orthogonally modulated by the plurality of sequences of modulation signals and are frequency-converted to a frequency band used for communication by the mobile terminal to be tested;
A plurality of transmission antennas (45 _{1 to} 45 _N ) that respectively receive a plurality of series of downlink signals output from the transmission unit;
A receiving antenna (46) for receiving an uplink signal output by the mobile terminal with respect to radio waves output from the transmitting antenna;
A receiver (60) capable of receiving and demodulating the uplink signal and the downlink signal;
A reception signal changeover switch (40, 40 ', 41) for selectively inputting either the uplink signal or the downlink signal to the reception unit;
In the test mode for performing a test by communication with the mobile terminal, the baseband signal is output from the signal selection switch, and in the phase adjustment mode for performing phase alignment of the downlink signals of the plurality of series, Modulation switching control means (81) for outputting the DC signal from a signal selection switch;
Control at least the reception signal changeover switch, and in the test mode, the uplink signal output from the mobile terminal is input to the reception unit and demodulated. In the phase adjustment mode, the uplink signal is converted to the uplink signal. Instead, received signal switching control means (83) for selectively inputting the downlink signals of the plurality of sequences one by one to the receiving unit and demodulating them,
Phase detection means (84) for detecting a phase of a signal sequentially demodulated by the receiving unit in the phase adjustment mode;
From the phase sequentially detected by the phase detection means, a phase shift amount necessary for matching all phases of the downlink signals of the plurality of series output from the transmission unit is obtained, and the characteristic coefficient of the transmission path information giving means is obtained. A mobile terminal test apparatus comprising phase correction means (85) for correcting phase information by the amount of phase shift. A multiplexer (50) for multiplexing a plurality of sequences of downlink signals output by the transmitter;
The reception signal changeover switch is configured to select one of the output of the reception antenna and the output of the multiplexer and give it to the reception unit,
The received signal switching control means includes
In the test mode, the reception signal changeover switch causes the output of the reception antenna to be input to the reception unit, and in the phase adjustment mode, the reception signal changeover switch outputs the output of the multiplexer to the reception unit. The gain used for one series of modulation signals is set to a predetermined value other than 0 and the gain used for the other series of modulation signals among the gains of the characteristic coefficients of the transmission path information giving means. 2. The mobile terminal test apparatus according to claim 1, wherein when set to 0, one series of downlink signals is selectively given to the multiplexer. The reception signal changeover switch is configured to selectively output any one of a plurality of series of downlink signals output from the transmission unit and the output of the reception antenna,
The received signal switching control means includes
In the test mode, the reception signal change-over switch causes the output of the reception antenna to be input to the receiving unit, and in the phase adjustment mode, the reception signal change-over switch receives the plurality of sequences of downlink signals as one sequence. The mobile terminal test apparatus according to claim 1, wherein the reception unit is input one by one. Performs arithmetic processing using characteristic coefficients including gain and phase information of multiple transmission paths assumed between MIMO transmission and reception antennas for a fixed baseband DC signal, and outputs multiple series of modulation signals Performing step (S11);
Outputting a plurality of sequences of downlink signals each orthogonally modulated with the plurality of modulation signals and frequency-converted to a frequency band used for communication by the mobile terminal to be tested (S11);
Selectively receiving and demodulating the plurality of downlink signals one by one and detecting the phase thereof (S12 to S16);
Obtaining a phase shift amount necessary to match all phases of the plurality of downlink signals from the detected phase, and correcting phase information of the characteristic coefficient by the phase shift amount (S17). A downlink signal phase adjustment method for a mobile terminal test apparatus.

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