Test system and test method

Abstract

Provided are a test system and a test method capable of simulating a propagation path environment while suppressing circuit scale, using a method for reproducing instantaneous characteristics of propagation path characteristics of an actual propagation path. 【Solution means】The test system 1 includes a singular value decomposition processing unit that performs singular value decomposition on the instantaneous characteristic H(k,n RS ) into the form of U0(k,n RS )D0(k,n RS )V0(k,n RS ), a signal conversion unit 24 that multiplies V0(k,n H ) by CSI-RS transmitted from N Tx transmit antennas to convert it into R parallel signals, a time domain signal generation unit 25 that generates an OFDM modulation signal from the R parallel signals, an OFDM modulation signal, and the product U0(k,n Tx )D0(k,n RS ) of U0(k,n H ) and D0(k,n RS ) to perform a convolution operation with the impulse response of U0(k,n RS )D0(k,n RS )D0(k,n RS ), and a convolution operation unit 41 that generates N Rx parallel test signals in the time domain received by N Rx receive antennas of the UE120.

Description

[Technical Field]

[0001] The present invention relates to a test system and a test method for reproducing the instantaneous characteristics of propagation path characteristics measured in an actual propagation path environment. [Background technology]

[0002] When testing mobile phone terminals (User Equipment: UE), the demodulation performance in a fading environment is evaluated by supplying the UE with a signal that has been passed through a propagation path simulator and output from a base station simulator as a downlink signal. Often, a channel model defined specifically for testing is used in the propagation path simulator. However, there is also a demand to evaluate the demodulation performance of the UE using propagation path characteristics that are closer to the actual propagation path environment (including the time evolution of propagation path characteristics due to the movement of the UE and surrounding objects).

[0003] As a method for simulating the actual propagation path environment, for example, the method disclosed in Patent Documents 1 and 2 is known.

[0004] The method disclosed in Patent Document 1 involves parameterizing the statistical properties of the measured propagation path characteristics and converting them into a channel model to simulate the propagation path environment. This allows for evaluation of whether the channel model can accurately simulate the propagation path characteristics in an actual propagation path environment.

[0005] The method disclosed in Patent Document 2 reduces the circuit size of the test system by processing the propagation path characteristics, which have a large number of transmitting antennas, in the frequency domain. [Prior art documents] [Patent Documents]

[0006] [Patent Document 1] Japanese Patent Publication No. 2024-168749 [Patent Document 2] Japanese Patent Publication No. 2019-009493 [Overview of the Initiative] [Problems that the invention aims to solve]

[0007] The method disclosed in Patent Document 1 does not reproduce the instantaneous characteristics of the propagation path characteristics of an actual propagation path. For this reason, propagation path simulations using channel models such as the TDL model (Tapped Delay Line model) in Patent Document 1 can only simulate statistically uniform conditions, making it difficult to simulate changes in propagation path characteristics that occur due to the movement of the UE and surrounding objects.

[0008] Furthermore, the method disclosed in Patent Document 2 does not reproduce the instantaneous characteristics of the propagation path characteristics of an actual propagation path, and involves complex processing to introduce the effects of multipath and Doppler frequency shift in the frequency domain.

[0009] The present invention was made to solve these conventional problems, and aims to provide a test system and test method that can simulate the propagation path environment while keeping the circuit size down by using a method that reproduces the instantaneous characteristics of the propagation path characteristics of an actual propagation path. [Means for solving the problem]

[0010] To solve the above problems, the test system according to the present invention is N Rx A test system (1) that transmits a test signal to an object under test (120) having N receiving antennas, wherein the network-side transmitting and receiving device (100) has N Tx Individual transmitting antennas (Tx#1~Tx#N) Tx The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Rx Individual receiving antennas (Rx#1~Rx#N) Rx Using the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f k and timing t nRS Instantaneous characteristics H(k,n) of the propagation path characteristics of each actual propagation path RSAn actual propagation path characteristic calculation unit (31) that calculates RS ), and with the number of effective singular values being R, the instantaneous characteristic H(k,n RS ) is H(k,n RS ) = U0(k,n RS )D0(k,n RS ) H is subjected to singular value decomposition in the form of, and N Rx a submatrix U0 of a unitary matrix of N rows and R columns, and a diagonal matrix D0(k,n RS ) of R rows and R columns whose diagonal components are the effective singular values of the instantaneous characteristic H(k,n RS ), and N Tx a submatrix V0(k,n RS ) of a unitary matrix of N rows and R columns and the adjoint matrix V0(k,n RS ) H and, a singular value decomposition processing unit (33) that calculates, a test reference signal transmitted from the N Tx transmitting antennas, a modulation signal of test data to be transmitted to the object under measurement, and N Tx parallel test signals including the test reference signal in the frequency domain and the modulation signal in the frequency domain, a test signal generation unit (26) that generates, for the N Tx parallel test signals, multiplies by the adjoint matrix V0(k,n RS ) H to convert the N Tx parallel test signals into R parallel signals, a time domain signal generation unit (25) that performs Fourier inverse transform processing on the R parallel signals to generate a time domain signal, and convolution operation with the impulse response of the product U0(k,n RS )D0(k,n RS ) of the time domain signal generated by the time domain signal generation unit and the submatrix U0(k,n RS ) of the unitary matrix and the diagonal matrix D0(k,n RS ) to generate the N Rx parallel test signals in the time domain received by the N Rx receiving antennas of the object under measurement, a convolution operation unit (41) that performs, and includes.

[0011] Note that, the above V0(k,n RS) H This is the matrix V0(k,n RS This is the conjugate transpose (Hermitian transpose) of ). Hereafter, V0(k,n RS Similarly, for matrices other than ) "A H Let " represent the conjugate transpose (Hermitian transpose) of matrix A. Also, for vectors, "a (bold) H Let " represent the conjugate transpose (Hermitian transpose) of vector a (bold).

[0012] With this configuration, the test system according to the present invention can simulate the propagation path environment by using a method that reproduces the instantaneous characteristics of the propagation path characteristics of an actual propagation path, while keeping the circuit size after the time-domain signal generation unit low.

[0013] Furthermore, since the test system according to the present invention employs a method for reproducing the instantaneous characteristics of the propagation path characteristics of an actual propagation path, it can simulate propagation path characteristics involving the movement of the UE and surrounding objects.

[0014] Furthermore, the test system according to the present invention has instantaneous characteristics H(k,n RS ) to V0(k,n RS ) H and the product U0(k,n RS )D0(k,n RS By dividing the processing into frequency domain and time domain, it is possible to achieve a simple configuration while simultaneously reducing the number of antennas in the frequency domain and obtaining the effects of multipath and Doppler frequency shift in the time domain.

[0015] Furthermore, the test system according to the present invention is N Rx A test system (1) that transmits a test signal to an object under test (120) having N receiving antennas, wherein the network-side transmitting and receiving device (100) has N Tx Individual transmitting antennas (Tx#1~Tx#N) Tx The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Rx Individual receiving antennas (Rx#1~Rx#N) RxUsing the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f k and timing t nRS Instantaneous characteristics H(k,n) of the propagation path characteristics of each actual propagation path RS The actual propagation path characteristics calculation unit (31) calculates the instantaneous characteristics H(k,n RS An interpolation processing unit (32) interpolates ) in the time axis direction to generate an interpolated propagation path characteristic H(k,n) with a sampling rate that satisfies the sampling theorem, and sets the number of valid singular values ​​to H(k,n) = U0(k,n)D0(k,n)V0(k,n) H We decompose the singular value into the form N Rx A submatrix U0 of a unitary matrix with rows and columns R, and a diagonal matrix D0(k,n) of rows and columns R, where the diagonal elements are the effective singular values ​​of the interpolation propagation path characteristic H(k,n), and N Tx The adjoint matrix V0(k,n) of a submatrix V0(k,n) of a unitary matrix with rows and columns R. H A singular value decomposition processing unit (33) calculates the N Tx A test reference signal transmitted from a transmitting antenna, a modulated signal for test data to be transmitted to the object under test, and an N including the test reference signal in the frequency domain and the modulated signal in the frequency domain. Tx A test signal generation unit (26) that generates parallel test signals and the N Tx The adjoint matrix V0(k,n) is used for the parallel test signals. H By multiplying by the above N Tx A signal conversion unit (24) converts parallel test signals into R-parallel signals; a time-domain signal generation unit (25) performs an inverse Fourier transform on the R-parallel signals to generate a time-domain signal; and a convolution operation is performed between the time-domain signal generated by the time-domain signal generation unit and the impulse response of the product U0(k,n)D0(k,n) of the submatrix U0(k,n) of the unitary matrix and the diagonal matrix D0(k,n), and the N of the object under measurement is calculated. Rx The time domain N received by each receiving antenna Rx The configuration includes a convolution unit (41) that generates the parallel test signals.

[0016] With this configuration, the test system according to the present invention can simulate the propagation path environment by using a method that reproduces the instantaneous characteristics of the propagation path characteristics of an actual propagation path, while keeping the circuit size after the time-domain signal generation unit low.

[0017] Furthermore, since the test system according to the present invention employs a method for reproducing the instantaneous characteristics of the propagation path characteristics of an actual propagation path, it can simulate propagation path characteristics involving the movement of the UE and surrounding objects.

[0018] Furthermore, the test system according to the present invention uses V0(k,n) to determine the interpolated propagation path characteristics H(k,n). H By dividing the signal into a product U0(k,n)D0(k,n) and performing processing in the frequency domain and time domain respectively, a simple configuration can be achieved while reducing the number of antennas in the frequency domain and obtaining the effects of multipath and Doppler frequency shift in the time domain.

[0019] Furthermore, the test system according to the present invention comprises a test signal generation unit (21) that generates the modulation signal in the frequency domain, and the N Tx A beamforming process equivalent to a computational process is performed on the modulated signal in the frequency domain to make the beam characteristics of the radio waves of the downlink signal transmitted from each transmitting antenna a desired characteristic, N Tx A beamforming processing unit (22) that generates parallel beamforming processing signals, and the N Tx The parallel beamforming processing signals are each added to the frequency domain test reference signals, and the N Tx The configuration may also include an integration unit (23) that generates parallel test signals.

[0020] Furthermore, the test system according to the present invention is the adjoint matrix V0(k,n RS ) H Or V0(k,n) H The impulse response and the product U0(k,n RS )D0(k,n RS) Or a propagation path characteristic memory unit (35) that stores the impulse response of U0(k,n)D0(k,n), and the signal conversion unit reads the adjoint matrix V0(k,n from the propagation path characteristic memory unit RS ) H Or the impulse response of V0(k,n) is converted back to the adjoint matrix V0(k,n in the frequency domain RS ) H Or V0(k,n) H After performing the conversion to return to, the adjoint matrix V0(k,n in the frequency domain RS ) H Or V0(k,n) H Is multiplied by the N Tx Parallel test signals, and the convolution operation unit performs a convolution operation between the time-domain signal generated by the time-domain signal generation unit and the product U0(k,n read from the propagation path characteristic memory unit RS )D0(k,n RS ) Or the impulse response of U0(k,n)D0(k,n). Such a configuration may be adopted.

[0021] With this configuration, the test system according to the present invention can compress the data of V0(k,n RS ) H Or V0(k,n) H By converting the data of into the form of an impulse response, and save it in the propagation path characteristic memory unit. RS ) H Or V0(k,n) H The data of can be information-compressed and stored in the propagation path characteristic memory unit.

[0022] Further, in the test system according to the present invention, the singular value decomposition processing unit makes the elements of the product U0(k,n RS )D0(k,n RS ) Or U0(k,n)D0(k,n), and the elements of the column vectors constituting the submatrix V0(k,n RS ) Or V0(k,n) of the unitary matrix are continuously changed between the instantaneous characteristics H(k,n RS ) Or the interpolated propagation path characteristics H(k,n) adjacent on the frequency axis and the time axis, so that the diagonal matrix D0(k,n RS) or the permutation of the singular values constituting D0(k,n), and the submatrix U0(k,n of the unitary matrix RS ) or the permutation and phase adjustment of the column vectors constituting U0(k,n), and the submatrix V0(k,n of the unitary matrix RS ) or a configuration that performs the permutation and phase adjustment of the column vectors constituting V0(k,n) may be used.

[0023] With this configuration, the test system according to the present invention can, if necessary, perform the permutation of the singular values constituting the diagonal matrix D0(k,n RS ) or D0(k,n), the permutation and phase adjustment of the column vectors constituting the submatrix U0(k,n of the unitary matrix RS ) or U0(k,n), and the permutation and phase adjustment of the column vectors constituting the submatrix V0(k,n) of the unitary matrix, thereby ensuring the continuity between adjacent instantaneous characteristics H(k,n RS ) or the interpolation propagation path characteristics H(k,n) on the frequency axis and the time axis.

[0024] Further, in the test system according to the present invention, the convolution operation unit may perform the convolution operation by aligning the signal in the time domain including the test reference signal with the timing of the impulse response of the product U0(k,nD0(k,n) at the timing n RS including the test reference signal.

[0025] With this configuration, the test system according to the present invention can match the propagation path characteristics observed by the UE by referring to the test reference signal in the simulation environment with the propagation path characteristics observed by the antenna device through the reference signal in the actual propagation path environment by performing the convolution operation by aligning the timing with the impulse response of the product U0(k,n RS )D0(k,n RS )D0(k,n RS ) at the timing n including the test reference signal.

[0026] Further, the test method according to the present invention is NRx A test method for transmitting a test signal to an object under test (120) having N receiving antennas, wherein the network-side transmitting / receiving device (100) has N Tx Individual transmitting antennas (Tx#1~Tx#N) Tx The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Rx Individual receiving antennas (Rx#1~Rx#N) Rx Using the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f k and timing t nRS Instantaneous characteristics H(k,n) of the propagation path characteristics of each actual propagation path RS The actual propagation path characteristics calculation step (S2) calculates the instantaneous characteristics H(k,n RS An interpolation process step (S3) is performed by interpolating ) in the time axis direction to generate an interpolated propagation path characteristic H(k,n) with a sampling rate that satisfies the sampling theorem, and the number of valid singular values ​​is R, and the interpolated propagation path characteristic H(k,n) is given by H(k,n)=U0(k,n)D0(k,n)V0(k,n) H We decompose the singular value into the form N Rx A submatrix U0 of a unitary matrix with rows and columns R, and a diagonal matrix D0(k,n) of rows and columns R, where the diagonal elements are the effective singular values ​​of the interpolation propagation path characteristic H(k,n), and N Tx The adjoint matrix V0(k,n) of a submatrix V0(k,n) of a unitary matrix with rows and columns R. H The singular value decomposition process step (S4) for calculating the N Tx A test reference signal transmitted from a transmitting antenna, a modulated signal for test data to be transmitted to the object under test, and an N including the test reference signal in the frequency domain and the modulated signal in the frequency domain. Tx Steps to generate parallel test signals (S5~S7), and the N Tx The adjoint matrix V0(k,n) is used for the parallel test signals. H By multiplying by the above N TxA signal conversion step (S8) converts parallel test signals into R-parallel signals; a time-domain signal generation step (S9) performs an inverse Fourier transform on the R-parallel signals to generate a time-domain signal; and a convolution operation is performed between the time-domain signal generated in the time-domain signal generation step and the impulse response of the product U0(k,n)D0(k,n) of the submatrix U0(k,n) of the unitary matrix and the diagonal matrix D0(k,n), and the N of the object under measurement is determined. Rx The time domain N received by each receiving antenna Rx The configuration includes a convolution operation step (S10) for generating the parallel test signals. [Effects of the Invention]

[0027] The present invention provides a test system and test method that can simulate the propagation path environment while keeping the circuit size down by using a method that reproduces the instantaneous characteristics of the propagation path characteristics of an actual propagation path. [Brief explanation of the drawing]

[0028] [Figure 1] This diagram schematically illustrates the environment of the actual propagation path between a base station and an antenna device. [Figure 2] This is a block diagram showing the configuration of a test system according to an embodiment of the present invention. [Figure 3] This diagram illustrates the frequency domain characteristics of the propagation path and the time domain characteristics showing its evolution over time. [Figure 4] This figure shows the specific configuration of the test equipment and pseudo-propagation path included in the test system according to an embodiment of the present invention. [Figure 5] This diagram shows a typical configuration of a conventional base station simulator and a propagation path simulator. [Figure 6] This is a schematic diagram illustrating the propagation path characteristics and digital beamforming between the base station and the UE. [Figure 7] This is a flowchart illustrating the process of a test method using the test system according to an embodiment of the present invention. [Modes for carrying out the invention]

[0029] Hereinafter, embodiments of the test system and test method according to the present invention will be described with reference to the drawings.

[0030] Figure 1 schematically shows the environment of the actual propagation path 110, which is a MIMO propagation path between a base station 100 and an antenna device 10, which are examples of network-side transceivers. In Figure 1, data communication between the base station 100 and the antenna device 10 is performed using multiple subcarriers with OFDM (Orthogonal Frequency Division Multiplexing) modulation.

[0031] The antenna device 10, in an environment of a real propagation path 110 consisting of multiple channels, provides N of the base station 100 Tx Transmitting antennas Tx#1~Tx#N Tx It receives downlink signals transmitted from the base station 100. For example, antenna device 10 is an air monitor or UE. Antenna device 10 is the transmitting antenna Tx#1~Tx#N of base station 100. Tx N receives the downlink signal transmitted from as the received signal. Rx Individual receiving antennas Rx#1~Rx#N Rx It also includes an IQ data output unit 11.

[0032] Here, the transmitting antennas Tx#1~Tx#N of base station 100. Tx Number of items N Tx And the receiving antennas Rx#1~Rx#N of the antenna device 10. Rx Number of items N Rx These are integers greater than or equal to 2 and greater than or equal to 1, respectively, and N Tx ×N Rx This value represents the number of channels in the actual propagation path 110.

[0033] The IQ data output unit 11 outputs to the receiving antennas Rx#1 to Rx#N of the antenna device 10. Rx N received by RxThe system is configured to perform reception processing on each received signal, such as amplification, frequency conversion, and analog-to-digital conversion. Furthermore, the IQ data output unit 11 processes the received N Rx The individual received signals are demodulated, N Rx The system generates a pair of mutually orthogonal I-component baseband signals and Q-component baseband signals. In this specification, the I-component baseband signal and Q-component baseband signal are collectively referred to simply as "IQ data".

[0034] The reference signals (RS) included in the IQ data output from the IQ data output unit 11 of the antenna device 10 are, for example, CSI-RS (Channel State Information Reference Signal), DMRS (Demodulation Reference Signal), TRS (Tracking Reference Signal), and PTRS (Phase Tracking Reference Signal) in the case of the 5G NR standard.

[0035] In this embodiment, the above-mentioned example of using CSI-RS in the frequency range FR1 (Frequency Range 1) of the 5G NR standard as the reference signal is explained, but the reference signal is not limited to CSI-RS and may be any other RS ​​as described above.

[0036] If the reference signal is CSI-RS, the transmitting antennas are Tx#1 to Tx#N. Tx Number of items N Tx The pin number will be one of 4, 8, 12, 16, 24, or 32, and the receiving antenna Rx#1 to Rx#N will be Rx#1 to Rx#N. Rx Number of items N Rx The situation in which either 2 or 4 occurs is an example of a situation to which the present invention can be applied. In particular, receiving antennas Rx#1 to Rx#N Rx Number of items N Rx Compared to the transmitting antenna Tx#1~Tx#N Tx Number of items N Tx When the size is large, the present invention is highly effective in reducing the circuit size of the test apparatus.

[0037] h in Figure 1 1,1 (k,n) ,h 2,1 (k,n) ,···,h NRx,1 (k,n) ,h 1,2 (k,n) ,h 2,2 (k,n) ,···,h NRx,2 (k,n) ,···,h 1,NTx (k,n) ,h 2,NTx (k,n) ,···,h NRx,NTx (k,n) This is as shown in equation (3) below, N Tx ×N Rx These are the elements of the propagation path matrix in the frequency domain for MIMO.

[0038] As shown in Figure 2, the test system 1 of this embodiment is N Rx The system transmits a test signal to an object under test (UE) 120 having a receiving antenna, and includes a test device 20, a propagation path characteristic acquisition unit 30, and a pseudo propagation path 40.

[0039] The test device 20 is equipped with the functions of a base station simulator that generates the downlink signal necessary to test the UE120, transmits the generated downlink signal to the UE120 via a pseudo-propagation path 40, receives the uplink signal transmitted from the UE120, and performs the processing necessary for the test. The test device 20 is configured, for example, to test the demodulation performance of the UE120. The pseudo-propagation path 40 between the test device 20 and the UE120 is formed by calculations performed by a convolution unit 41, which will be described later. The UE120 is a UE capable of communication using at least the MIMO or MISO (Multiple Input Single Output) method.

[0040] The propagation path characteristic acquisition unit 30 includes an actual propagation path characteristic calculation unit 31, an interpolation processing unit 32, a singular value decomposition processing unit 33, an impulse response calculation unit 34, and a propagation path characteristic storage unit 35.

[0041] The actual propagation path characteristics calculation unit 31 calculates the N output from the IQ data output unit 11. Rx By performing an FFT (Fast Fourier Transform) on each OFDM symbol of the set of IQ data and analyzing the CSI-RS, a known reference signal included in the frequency domain IQ data, the instantaneous characteristics H(k,n) of the propagation path characteristics in the frequency domain of the multiple channels constituting the actual propagation path 110 are obtained. RS ) subcarrier f k and timing t nRS It is designed to calculate for each N Tx Transmitting antennas Tx#1~Tx#N Tx The instantaneous characteristic H(k,n) occurs only at the timing when CSI-RS is transmitted. RS ) can be obtained.

[0042] Here, the instantaneous characteristic H(k,n RS ) is expressed as shown in equation (1) below. y,x (k,n) The instantaneous characteristic H(k,n RS This represents each element of ). y is the N of the antenna device 10. Rx Individual receiving antennas Rx#1~Rx#N Rx This is the index, from 1 to R Rx It is an integer up to 100. x is the N of base stations 100. Tx Transmitting antennas Tx#1~Tx#N Tx This is an index, ranging from 1 to N. Tx It is an integer up to 1.

[0043] That is, N Rx = 1 and N Tx ≥2 is MISO format, N Rx ≥2 and N Tx ≥2 indicates the MIMO scheme.

[0044]

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[0045] In equation (1), k is the sample number on the frequency axis, for example, the index of the subcarrier number. Also, n RS This is the time-axis sample number corresponding to the timing of CSI-RS in the downlink signal transmitted from base station 100, and is, for example, the index of the OFDM symbol number. Also, propagation path characteristics h y,x (k,n) Assume that the average power is normalized to 1.

[0046] Instantaneous characteristics H(k,n RS Each element h y,x (k,nRS) This includes information on the amplitude and phase variation of the CSI-RS in the IQ data obtained from the received signal received by the y-th receiving antenna Rx#y, relative to a known CSI-RS transmitted by the x-th transmitting antenna Tx#x.

[0047] The pseudo-propagation path 40 functions as a propagation path simulator formed between the test device 20 and the UE120. The pseudo-propagation path 40 is configured to regenerate propagation path characteristics (hereinafter also referred to as interpolated propagation path characteristics H(k,n)) that have been interpolated as needed by the interpolation processing unit 32, which will be described later.

[0048] As shown in Figure 3, a certain instantaneous characteristic H(k,n RS Regarding ), a certain k (a certain frequency f) on the frequency axis f. k ) in n RS (Timing t) nRS A series of data obtained by varying the time axis t-direction of ) shows the instantaneous characteristic H(k,n RS This represents the instantaneous characteristics in the time domain, showing the change in instantaneous values ​​along the time axis of ). The graph on the right in Figure 3 shows the instantaneous characteristics H(k,n RS This is a vector representation of the real and imaginary parts of the time-domain instantaneous characteristics of ). The lower graph in Figure 3 shows the instantaneous characteristics H(k,n RS This is a vector representation of the real and imaginary parts of the frequency domain characteristics of ).

[0049] The propagation path characteristics in the actual propagation path 110 can be directly measured at each period T (e.g., T = 20 msec to 80 msec) during which a reference signal such as CSI-RS is transmitted. The maximum Doppler frequency f of the actual propagation path 110 d The relationship between period T is often as shown in equation (2) below, but such a situation does not satisfy the Nyquist criterion in the sampling definition.

[0050]

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[0051] For example, if T=80msec, the Nyquist standard is met by f d This applies when the carrier frequency is <6.25Hz, and when the carrier frequency is 5GHz, it is limited to when the UE120's moving speed v is v < 1.35km / h.

[0052] On the other hand, the time-domain instantaneous characteristic data of the interpolated propagation path characteristic H(k,n) reconstructed by the pseudo-propagation path 40 (hereinafter also referred to as "instantaneous propagation path waveform data") must be waveform data sampled at a sufficient sampling rate (e.g., 10 kHz) that satisfies the sampling theorem.

[0053] Therefore, the interpolation processing unit 32 determines the instantaneous characteristic H(k,n RS ) sample interval (n RS If the interval between k, n does not satisfy the sampling theorem, the instantaneous characteristic H(k, n RS The system interpolates the values ​​in the time axis direction to generate time-series data of the interpolated propagation path characteristic H(k,n) that satisfies the Nyquist criterion in the sampling theorem, i.e., instantaneous propagation path waveform data where n is the sample number on the time axis, as shown in equation (3) below.

[0054] In this specification, the instantaneous characteristic H(k,n RS If the sample interval of ) satisfies the sampling theorem, then the instantaneous characteristic H(k,n RSThe interpolation propagation path characteristic H(k,n) itself is the interpolation propagation path characteristic H(k,n), and the interpolation processing unit 32 is the instantaneous characteristic H(k,n RS The result of ) is output directly as the interpolated propagation path characteristic H(k,n).

[0055]

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[0056] The interpolation processing by the interpolation processing unit 32 can be implemented, for example, by utilizing a known Kalman filter. This method is disclosed, for example, in Nopphon Keerativoranan, Jun-ichi Takada, "Interpolation of Sparely-Sampled Time-Variant Channel Response in 1D Trajectory Utilizing Ensemble Kalman Filter," 2022 IEEE 33rd Annual International Symposium on Personal, Indoor and Mobile Radio Communications.

[0057] The singular value decomposition processing unit 33 decomposes the interpolated propagation path characteristic H(k,n), which has been interpolated by the interpolation processing unit 32, into singular values ​​as shown in equation (4) below. In equation (4), U(k,n) is N Rx Row N Rx The unitary matrix of the column, V(k,n), is N. Tx Row N Tx This is a unitary matrix of columns. D(k,n) is N Rx Row N Tx A matrix of columns, N Rx Row N Rx The elements of the diagonal matrix of the column, and N Rx Row N Tx -N Rx This is a matrix in which the elements of the zero-column matrix are arranged in parallel. H The symbol '' represents the conjugate transpose (Hermitian transpose) of matrix A.

[0058] D0(k,n) contains R valid singular values ​​λ. i,i This is an R x R diagonal matrix whose diagonal elements are (k,n) (singular values ​​of non-negligible magnitude). Here, i is an integer from 1 to R. U0(k,n) is the column vector that makes up U(k,n) containing R singular values ​​λ. i,i N is composed of column vectors corresponding to (k,n). Rx This is a submatrix of a unitary matrix with R rows and R columns. V0(k,n) is a submatrix of the R singular values ​​λ of the column vectors that make up V(k,n). i,i N is composed of column vectors corresponding to (k,n). Tx This is a submatrix of a unitary matrix with rows and columns R.

[0059] Note that the instantaneous characteristic H(k,n RS If the sample interval of ) satisfies the sampling theorem, then U(k,n), U0(k,n), V(k,n), V0(k,n), D(k,n), D0(k,n), λ i,i (k,n), and the notation for sample number n in various other parameters, should be expressed as follows: sample number n RS It can be replaced with this.

[0060]

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[0061] In other words, as shown in equation (4), the singular value decomposition processing unit 33 interpolates the propagation path characteristics H(k,n) as follows, where R is the number of valid singular values: H(k,n) = U0(k,n)D0(k,n)V0(k,n) H We decompose the singular value into the form N Rx A submatrix U0(k,n) of a unitary matrix with rows and columns R, and a diagonal matrix D0(k,n) with rows and columns R, where the diagonal elements are effective singular values ​​of the interpolated propagation path characteristic H(k,n), and N Tx The adjoint matrix V0(k,n) of the submatrix V0 of the unitary matrix with rows and columns R. H And, it is designed to calculate.

[0062] Equation (4) can also be written as equation (5) below.

[0063]

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[0064] As shown in equation (5), the singular value decomposition of the interpolated propagation path characteristic H(k,n) is λ i,i (k,n) And the column vector u that constitutes U0(k,n) (bold) i And the conjugate transpose v of the column vectors that make up V0(k,n) (bold) i H It can be expressed as a sum of the product of i=1 to R. i,i (k,n) u (bold) i v (bold) i H Each term is equivalent, and there is no basis for determining their order. When representing it as a matrix, the result remains the same even if the order of the singular values ​​and their corresponding column vectors is swapped. For example, even if the first and second column vectors and their corresponding singular values ​​are swapped and expressed as in equation (6) below, the result of the operation is equivalent.

[0065]

number

[0066] As a convention when displaying the results of singular value decomposition, the singular values, which are the diagonal elements of the diagonal matrix D0(k,n), are represented as λ 1,1 (k,n) ≥λ 2,2 (k,n) ≧···≧λ R,R (k,n) They are often displayed in descending order. The column vector order determined by this convention is used for U0(k,n), D0(k,n), and V0(k,n) on the frequency and time axes. H When the samples are arranged in order, it is possible that continuity regarding the order of the column vectors may or may not be guaranteed.

[0067] That is, R singular values ​​λ 1,1 (k,n) ,λ2,2 (k,n) ,···,λ R,R (k,n) If there is a clear difference in the magnitude of each of them, and the correspondence does not change in the frequency and time axes, then the continuity of the order of the column vectors is guaranteed. On the other hand, the R singular values ​​λ 1,1 (k,n) ,λ 2,2 (k,n) ,···,λ R,R (k,n) If values ​​of roughly the same magnitude are included within the column vectors, and their magnitudes are reversed along the frequency or time axis, then continuity in the order of the column vectors cannot be guaranteed.

[0068] Also, U0(k,n)D0(k,n) and V0(k,n) H The relative phase relationship has degrees of freedom as shown in equation (7) below, which may be a factor in ensuring the continuity of the phase in the frequency axis or time axis direction.

[0069]

number

[0070] Therefore, eliminating the "possibility that continuity regarding the rearrangement of column vectors is not guaranteed" and the "possibility that continuity of the phase is not guaranteed" as explained above, U0(k,n)D0(k,n) and V0(k,n) H Processing is required to ensure continuity when the samples are arranged on the frequency and time axes. Such mathematical processing is publicly known, and one example of such processing is described in David W. Browne, Michael W. Browne, Michael P. Fitz, "Untangling the SVD's of Random Matrix Sample Paths," arXiv:math / 0610088v1 [math.ST] 2 Oct 2006.

[0071] Therefore, the singular value decomposition processing unit 33 takes the elements of the product U0(k,n)D0(k,n) of the submatrix U0(k,n) of the unitary matrix and the diagonal matrix D0(k,n), and the column vector v (bold) that constitutes the submatrix V0(k,n) of the unitary matrix. i The singular values ​​λ that constitute the diagonal matrix D0(k,n) change continuously between adjacent interpolation propagation path characteristics H(k,n) in the frequency and time axes. i,i (k,n) The rearrangement and the column vectors u (bold) that constitute the submatrix U0(k,n) of the unitary matrix. i Rearrangement and phase adjustment, and the column vectors v (bold) that constitute the submatrix V0(k,n) of the unitary matrix. i It is designed to rearrange the elements and adjust their phases.

[0072] The propagation path characteristic memory unit 35 stores V0(k,n) calculated by the impulse response calculation unit 34, which will be described later. H The impulse response of the function and the impulse response of the product U0(k,n)D0(k,n) are stored.

[0073] The impulse response calculation unit 34 uses, for example, IDFT (Inverse Digital Fourier Transformation) to convert the frequency characteristics into an impulse response, and performs singular value decomposition and ensures continuity for U0(k,n), D0(k,n), and V0(k,n) by the singular value decomposition processing unit 33. H The frequency characteristics in each frequency axis direction are converted into a time-varying impulse response (corresponding to each sample number n).

[0074] The impulse response calculation unit 34 uses the following equations (8a) to (8f), which express the IDFT as a matrix, to calculate U0(k,n), D0(k,n), and V0(k,n). H The impulse response can be calculated from the frequency characteristics.

[0075]

number

[0076] When the frequency characteristics in equation (8a) are known, the generalized inverse matrix W of the DFT matrix W is + Using this, the impulse response can be calculated as shown in equation (9) below.

[0077]

number

[0078] Alternatively, the impulse response calculation unit 34 may, for example, utilize the SAGE (Space-Alternating Generalized Expectation-maximization) algorithm to calculate U0(k,n), D0(k,n), and V0(k,n) in situations where the number of taps in the impulse response is limited. H The impulse response may be calculated to accurately reproduce the frequency characteristics of each of the elements. For details on the SAGE algorithm, see, for example, Bernard H. Fleury, Martin Tschudin, Ralf Heddergott, Dirk Dahlhaus, and Klaus Ingeman Pedersen, "Channel Parameter Estimation in Mobile Radio Environments Using the SAGE Algorithm", IEEE JOURNAL ON SELECTED AREAS IN COMMUNICATIONS, VOL. 17, NO. 3, MARCH 1999.

[0079] V0(k,n) H Although it is not necessary to convert it to an impulse response in principle, as it is multiplied as a frequency characteristic in the signal conversion unit 24 described later, the impulse response calculation unit 34 compresses the size of the instantaneous propagation path waveform data stored in the propagation path characteristic storage unit 35 by V0(k,n) H Convert this into an impulse response.

[0080] For example, in the 5G NR standard, V0(k,n)H When saving under the following conditions, storing it as an impulse response can compress the amount of data more effectively than saving it as a frequency response.

[0081] For example, V0(k,n) H When the frequency characteristics are stored in the propagation path characteristics storage unit 35, if the sample interval in the frequency axis direction is 1RB (Resource Block) width (12 subcarriers), the signal bandwidth is 273RB, and the number of bits for the real and imaginary parts is 2Bytes for the real part + 2Bytes for the imaginary part, the amount of data calculated for one OFDM symbol per channel is 273 × (2Bytes + 2Bytes) = 1092Bytes.

[0082] On the other hand, V0(k,n) H When the impulse response is stored in the propagation path characteristic memory unit 35, if the number of delay taps is 24 taps and the number of bits in the real and imaginary parts is 2 bytes for the real part and 2 bytes for the imaginary part, the amount of data calculated for one OFDM symbol per channel is 24 × (2 Bytes + 2 Bytes) = 96 Bytes.

[0083] Figure 4 shows a more specific configuration of the test apparatus 20 and the pseudo propagation path 40 in this embodiment.

[0084] The test apparatus 20 includes a modulation signal generation unit 21, a beamforming processing unit 22, an integration unit 23, a signal conversion unit 24, and a time-domain signal generation unit 25. The modulation signal generation unit 21, the beamforming processing unit 22, and the integration unit 23 constitute a test signal generation unit 26. The pseudo propagation path 40 includes a convolution calculation unit 41.

[0085] The test signal generation unit 26 is N Tx Transmitting antennas Tx#1~Tx#N Tx N includes a test reference signal in a similar format to the reference signal transmitted from, a modulated signal of test data to be transmitted to UE120, and the frequency domain test reference signal and frequency domain modulated signal. Tx It is designed to generate parallel test signals.

[0086] The modulated signal generation unit 21 generates an L for transmission to the UE120. Tx Test data for each layer in the frequency domain L Tx It is designed to convert (generate) parallel modulated signals and also generate frequency domain CSI-RS as a test reference signal. Tx The parallel modulated signal simulates the signal transmitted by the data channel, PDSCH (Physical Downlink Shared Channel). DMRS is a reference signal associated with the PDSCH.

[0087] The modulated signal generated by the modulated signal generation unit 21 is a modulated signal modulated by a multi-level modulation scheme such as BPSK (Binary Phase Shift Keying), QPSK (Quadrature Phase Shift Keying), 16QAM (Quadrature Amplitude Modulation), 64QAM, or 256QAM.

[0088] The beamforming processing unit 22 is N Tx Transmitting antennas Tx#1~Tx#N Tx L sent from Tx A digital beamforming process equivalent to digital arithmetic processing is performed on the frequency domain modulated signal generated by the modulation signal generation unit 21 to make the beam characteristics of the parallel downlink signal radio waves into desired characteristics, N Tx It is designed to generate parallel beamforming processing signals.

[0089] The integration unit 23 is N Tx The parallel beamforming processing signals are each added to the CSI-RS, which is used as a frequency domain test reference signal, and N Tx It is designed to generate parallel frequency domain test signals. The integration unit 23 can be configured, for example, as an adder.

[0090] Note that in the test signals, CSI-RS and N TxIf parallel beamforming processing signals are not simultaneously placed on the wireless resource (a wireless resource represented by two axes: frequency and time), the integration unit 23 simply performs N Tx The output will be either a parallel beamforming processing signal or CSI-RS. Therefore, the integration unit 23 will output N Tx It may be configured with a selector that outputs either a parallel beamforming processing signal or CSI-RS.

[0091] The signal conversion unit 24 reads V0(k,n) from the propagation path characteristic storage unit 35. H The impulse response of V0(k,n) in the frequency domain H After performing the conversion back, V0(k,n) in the frequency domain H to N Tx By multiplying the parallel test signals, N Tx The parallel test signal is converted into an R-parallel signal. For example, the signal conversion unit 24 uses equation (8a) to convert V0(k,n) H From the impulse response, V0(k,n) in the frequency domain H Perform the calculation process.

[0092] The time-domain signal generation unit 25 (25-1, 25-2, ..., 25-R) performs an inverse fast Fourier transform (IFFT), cyclic prefix (CP) addition, and bandwidth limiting on the R-parallel frequency-domain test signal converted by the signal conversion unit 24 to generate an OFDM-modulated time-domain signal (hereinafter also referred to as the "OFDM-modulated signal").

[0093] Integration unit 23 to each transmitting antenna Tx#1~Tx#N Tx The frequency domain test signal output in response to this is data in the form of constellations arranged along the frequency axis for each subcarrier (index k).

[0094] Here, the j-th transmitting antenna (where j is from 1 to N)Tx Constellation data transmitted by subcarrier #k in OFDM symbol #n by an integer up to s j (k,n) If we use this notation, the test signal output from the integration unit 23 will be data in the form of column vectors arranged in parallel on the frequency axis (index k) and the time axis (index n), as shown in equation (10) below.

[0095]

number

[0096] Figure 5 shows a typical processing configuration for a conventional base station simulator and a propagation path simulator. In the typical processing configuration, the data s for the j-th transmitting antenna Tx#j is obtained from the elements of the column vector in equation (10). j (k,n) However, this is input to the j-th time-domain signal generation unit 25-j' to generate an OFDM modulated signal, which is then transmitted to each of the transmitting antennas Tx#1~Tx#N Tx The corresponding signal is MIMO channel size N Tx ×N Rx It is input to the pseudo-propagation path 40'.

[0097] On the other hand, in the processing configuration of this embodiment shown in Figure 4, the column vector of equation (10) is V0(k,n) H By multiplying by the following equation (11), the number of elements becomes N Tx It is reduced from to R.

[0098]

number

[0099] Then, in the left side of equation (11), the j-th data sm (where j is an integer from 1 to R) in the column vector of R elements j (k,n) However, when input to the j-th time-domain signal generation unit 25-j, an OFDM modulated signal is generated, and each of the R OFDM modulated signals has a MIMO channel size of R × N.Rx It is input to the pseudo-propagation path 40.

[0100] In other words, in this embodiment, the signal conversion unit 24 calculates the number of paths after processing by the time-domain signal generation unit 25 as the number of transmitting antennas N. Tx Therefore, it can be reduced to R, which is the number of valid singular values. Note that R is N Tx and N Rx The smaller of the two values ​​(R ≤ Min(N) Tx ,N Rx )) For example, the number of transmitting antennas N Tx The number of receiving antennas is N, where the number of antennas is 32. Rx If the value is 4, R can be set to a value of 4 or less. This reduces the hardware resources required by the time-domain signal generation unit 25 and beyond.

[0101] The convolution unit 41 performs a convolution operation in the time domain between the OFDM modulated signal generated by the time-domain signal generation unit 25 and the impulse response of the product U0(k,n)D0(k,n) read from the propagation path characteristic storage unit 35, and the N of UE120 Rx The time domain N received by each receiving antenna Rx It is designed to generate parallel test signals.

[0102] In other words, the convolution unit 41 in this embodiment determines the MIMO channel size of the pseudo-propagation path 40 applied in the time domain as N Tx ×N Rx From R×N Rx It can be reduced to, for example, N Tx >N Rx In this case, R is R ≤ N Rx Because it fluctuates sequentially within the range, the pseudo-propagation path 40 has N instead of R. Rx We need to prepare individual routes.

[0103] In this embodiment, when testing the UE120 with the test device 20 and the pseudo-propagation path 40, the timing relationship between the OFDM modulated signal generated by the time-domain signal generation unit 25 and the interpolated propagation path characteristic H(k,n) reproduced by the pseudo-propagation path 40 is as follows.

[0104] In other words, the test system 1 of this embodiment generates a CSI-RS signal using a modulation signal generation unit 21, and the timing at which it is processed in the pseudo-propagation path 40, along with the instantaneous characteristics H(k,n) based on the direct measurement of the CSI-RS by the antenna device 10, are determined. RS The timing of the regeneration of the signal in the pseudo-propagation path 40 is synchronized with the timing of the regeneration.

[0105] This is, for example, the convolution unit 41 receives an OFDM modulated signal that includes CSI-RS as a test reference signal and timing n that includes CSI-RS as a test reference signal. RS This can be achieved by aligning the timing of the impulse response of the product U0(k,n)D0(k,n) and performing a convolution operation on the OFDM modulated signal that includes the same CSI-RS.

[0106] This makes it possible to match the propagation path characteristics observed by UE120 by referencing CSI-RS in the simulation environment with the propagation path characteristics observed by antenna device 10 through the same CSI-RS in the environment of the actual propagation path 110. In other words, the propagation path characteristics observed by UE120 are instantaneous characteristics H(k,n) determined by the interpolation processing unit 32. RS This avoids being affected by errors in the interpolation process.

[0107] Figure 6 is a schematic diagram illustrating the propagation path characteristics between a 5G NR base station and UE, and the digital beamforming used in FR1.

[0108] For example, when using PDSCH's DMRS as a reference signal, analyzing the DMRS simulates the propagation path characteristics, including digital beamforming or precoding characteristics ("Propagation path characteristics calculated by DMRS" in Figure 6). However, this method only allows measuring the propagation path characteristics for a given frequency band and time period where the data signal is present.

[0109] In contrast, the test system 1 of this embodiment simulates the "interpolated propagation path characteristics H(k,n) calculated by CSI-RS" shown in Figure 6. Since CSI-RS is a reference signal that is always transmitted from the base station at regular time intervals across a wide frequency band, the test system 1 of this embodiment can measure and reconstruct instantaneous propagation path characteristics across a wide frequency band at regular time intervals by analyzing CSI-RS.

[0110] In Figure 6, the number of physical antennas after analog beamforming is equal to the number of transmitting antenna ports N after digital beamforming. Tx That's all. In reality, the number of antennas after analog beamforming is the same as the number of transmitting antennas N. Tx If the above conditions are met, the obtained instantaneous characteristics H(k,n RS This does not affect the maximum number of transmission layers (Rank) of the RS being analyzed. In this specification, the transmitting antenna port of the RS being analyzed is referred to as the "transmitting antenna," and if there is, for example, analog beamforming after that, its characteristics are also considered to be included in the propagation path characteristics analyzed for the RS being analyzed.

[0111] Below, an example of a test method using the test system 1 of this embodiment will be described with reference to the flowchart in Figure 7. Note that explanations that overlap with the above-described explanation of the configuration of the test system 1 will be omitted as appropriate.

[0112] First, IQ data of the downlink signal from the base station 100 is input from the IQ data output unit 11 of the antenna device 10 to the propagation path characteristic acquisition unit 30 (step S1).

[0113] Next, the actual propagation path characteristics calculation unit 31 uses the CSI-RS included in the IQ data input in step S1 to calculate the subcarrier f k and timing t nRS Instantaneous characteristics H(k,n) of the propagation path characteristics of each actual propagation path 110 RS ) is calculated (actual propagation path characteristics calculation step S2).

[0114] Next, the interpolation processing unit 32 calculates the instantaneous characteristic H(k,n RS The interpolation is performed along the time axis to generate an interpolated propagation path characteristic H(k,n) with a sampling rate that satisfies the sampling theorem (interpolation processing step S3). However, interpolation processing is only necessary for the instantaneous characteristic H(k,n). RS ) sample interval (n RS This is the case when the interval between k and n does not satisfy the sampling theorem. RS If the sample interval of ) satisfies the sampling theorem, then the instantaneous characteristic H(k,n RS The interpolation path characteristic H(k,n) itself becomes the interpolation path characteristic.

[0115] Next, the singular value decomposition processing unit 33 calculates the interpolated propagation path characteristic H(k,n) as H(k,n) = U0(k,n)D0(k,n)V0(k,n) H We decompose the singular value into the form N Rx A submatrix U0 of a unitary matrix with rows and columns R, and a diagonal matrix D0(k,n) of rows and columns R, where the diagonal elements are effective singular values ​​of the interpolated propagation path characteristic H(k,n), and N Tx The adjoint matrix V0(k,n) of a submatrix V0(k,n) of a unitary matrix with rows and columns R. H And, calculate (singular value decomposition process step S4).

[0116] Next, the modulation signal generation unit 21 converts the test data to be transmitted to the UE120 into a frequency-domain modulation signal (modulation signal generation step S5).

[0117] Next, the beamforming processing unit 22 performs N Tx Transmitting antennas Tx#1~Tx#N TxA beamforming process equivalent to a computational process is performed on the frequency-domain modulated signal to make the beam characteristics of the downlink signal transmitted from the source the desired characteristics, N Tx A parallel beamforming processing signal is generated (beamforming processing step S6).

[0118] Next, the integration unit 23 is N Tx The parallel beamforming processing signals are each added to the CSI-RS, which is used as a frequency domain test reference signal, and N Tx Generate parallel test signals (addition step S7).

[0119] Next, the signal conversion unit 24, N Tx V0(k,n) is used as the parallel test signal. H By multiplying by N, Tx The parallel test signals are converted to R-parallel signals (signal conversion step S8).

[0120] Next, the time-domain signal generation units 25-1 to 25-R perform an inverse Fourier transform on the R-parallel signals to generate OFDM modulated signals (time-domain signal generation step (S9)).

[0121] Next, the convolution unit 41 performs a convolution operation between the OFDM modulated signal generated in the time-domain signal generation step S9 and the impulse response of the product U0(k,n)D0(k,n), and the N of UE120. Rx Individual receiving antennas Rx#1~Rx#N Rx The time domain N received by each Rx A parallel test signal is generated and the generated test signal is transmitted to the UE120 (convolution operation step S10).

[0122] As described above, the test system 1 according to this embodiment obtains the instantaneous characteristics H(k,n) of the propagation path characteristics in the environment of the actual propagation path 110. RS The interpolated propagation path characteristic H(k,n) including ) is given by H(k,n) = U0(k,n)D0(k,n)V0(k,n) HThe beamforming signal, to which CSI-RS has been added, is decomposed into a singular value form, and V0(k,n) is applied. H This is designed to be applied in the frequency domain.

[0123] As a result, the test system 1 according to this embodiment can simulate the propagation path environment by using a method that reproduces the instantaneous characteristics of the propagation path characteristics of the actual propagation path 110, while keeping the circuit size after the time-domain signal generation unit 25 down.

[0124] Furthermore, since the test system 1 according to this embodiment uses a method that reproduces the instantaneous characteristics of the propagation path characteristics of the actual propagation path 110, it can simulate propagation path characteristics involving the movement of the UE 120 and surrounding objects.

[0125] Furthermore, the test system 1 according to this embodiment uses V0(k,n) to determine the interpolated propagation path characteristics H(k,n). H By dividing the signal into a product U0(k,n)D0(k,n) and performing processing in the frequency domain and time domain respectively, a simple configuration can be achieved while reducing the number of antennas in the frequency domain and obtaining the effects of multipath and Doppler frequency shift in the time domain.

[0126] Furthermore, the test system 1 according to this embodiment has a frequency domain V0(k,n) H By converting the data into the format of an impulse response, V0(k,n) H The data can be compressed and stored in the propagation path characteristics storage unit 35.

[0127] Furthermore, the test system 1 according to this embodiment can ensure continuity between adjacent interpolated propagation path characteristics H(k,n) in the frequency and time axes by rearranging the singular values ​​constituting the diagonal matrix D0(k,n), rearranging and adjusting the phase of the column vectors constituting the submatrix U0(k,n) of the unitary matrix, and rearranging and adjusting the phase of the column vectors constituting the submatrix V0(k,n) of the unitary matrix, as needed.

[0128] Furthermore, the test system 1 according to this embodiment includes an OFDM modulated signal including CSI-RS and a timing n that includes CSI-RS. RS The product U0(k,n RS )D0(k,n RS By performing a convolution operation in sync with the impulse response of ), the propagation path characteristics observed by UE120 by referencing CSI-RS in the simulation environment can be matched with the propagation path characteristics observed by antenna device 10 through the same CSI-RS in the environment of the actual propagation path 110.

[0129] Furthermore, the test system 1 according to this embodiment can perform testing of the UE120 by reproducing the interpolated propagation path characteristics H(k,n) to recreate the propagation path characteristics of the actual propagation path 110.

[0130] In the embodiment described above, the network-side transceiver that transmits downlink signals toward the actual propagation path 110 is assumed to be a base station 100. However, instead of a base station, a Wi-Fi® access point or the like may be used as the network-side transceiver. [Explanation of Symbols]

[0131] 1. Test System 10 Antenna equipment 11. IQ Data Output Unit 20 Test equipment 21 Modulation signal generation unit 22 Beamforming Processing Unit 23. Integration Department 24 Signal conversion section 25 Time domain signal generator 26 Test signal generation unit 30 Propagation path characteristic acquisition unit 31 Actual propagation path characteristics calculation unit 32 Interpolation Processing Unit 33 Singular Value Decomposition Processing Unit 34 Impulse Response Calculation Unit 35 Propagation path characteristics memory unit 40 Pseudo-propagation paths 41 Convolution Unit 100 Base stations (network-side transceivers) 110 Actual propagation paths 120 Object under test (UE) Rx#1~Rx#N Rx Receiving antenna Tx#1~Tx#N Tx Transmitting antenna

Claims

1. N Ｒｘ A test system (1) that transmits a test signal to an object under test (120) having a receiving antenna, N of the network-side transceiver (100) Ｔｘ Individual transmitting antennas (Tx#1 to Tx#N) Ｔｘ The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Ｒｘ Individual receiving antennas (Rx#1 to Rx#N) Ｒｘ Using the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f ｋ and timing t ｎＲＳ Instantaneous characteristics H(k, n) of the propagation path characteristics of each actual propagation path ＲＳ The actual propagation path characteristics calculation unit (31) calculates the following: Let the number of effective singular values be \(R\), and the instantaneous characteristic \(H(k, n ＲＳ )\) be \(H(k, n ＲＳ ) = U ０ (k, n ＲＳ ) D ０ (k, n ＲＳ ) V ０ (k, n ＲＳ ) Ｈ Perform singular value decomposition in the form of, and \(N Ｒｘ The submatrix \(U ０ \) of the unitary matrix with \(R\) columns, and the diagonal elements are the effective singular values of the instantaneous characteristic \(H(k, n ＲＳ )\), the \(R\times R\) diagonal matrix \(D ０ (k, n ＲＳ )\), and \(N Ｔｘ The submatrix \(V ０ (k, n ＲＳ )^H\) of the unitary matrix with \(R\) columns, and the singular value decomposition processing unit (33) for calculating,​​​​​​ The aforementioned N Ｔｘ A test reference signal transmitted from a transmitting antenna, a modulated signal for test data to be transmitted to the object under test, and an N including the test reference signal in the frequency domain and the modulated signal in the frequency domain. Ｔｘ A test signal generation unit (26) that generates parallel test signals and The aforementioned N Ｔｘ The adjoint matrix V is used for the parallel test signals. ０ (k, n ＲＳ ) Ｈ By multiplying by the above N Ｔｘ A signal conversion unit (24) that converts parallel test signals into R-parallel signals, A time-domain signal generation unit (25) performs an inverse Fourier transform on the R-parallel signals to generate a time-domain signal, The time-domain signal generated by the time-domain signal generation unit and the submatrix U of the unitary matrix ０ (k, n ＲＳ ) and the aforementioned diagonal matrix D ０ (k, n ＲＳ ) and product U ０ (k, n ＲＳ ) D ０ (k, n ＲＳ A convolution operation is performed with the impulse response of the object being measured, and the N Ｒｘ The time domain N received by each receiving antenna Ｒｘ A test system comprising a convolution unit (41) that generates parallel test signals.

2. N Ｒｘ A test system (1) that transmits a test signal to an object under test (120) having a receiving antenna, N of the network-side transceiver (100) Ｔｘ Individual transmitting antennas (Tx#1 to Tx#N) Ｔｘ The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Ｒｘ Individual receiving antennas (Rx#1 to Rx#N) Ｒｘ Using the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f ｋ and timing t ｎＲＳ Instantaneous characteristics H(k, n) of the propagation path characteristics of each actual propagation path ＲＳ The actual propagation path characteristics calculation unit (31) calculates the following: The aforementioned instantaneous characteristics H(k, n) ＲＳ An interpolation processing unit (32) interpolates ) in the time axis direction to generate interpolated propagation path characteristics H(k,n) of a sampling rate that satisfies the sampling theorem, Let R be the number of valid singular values, and the interpolation propagation path characteristic H(k,n) be H(k,n) = U ０ (k, n) D ０ (k, n) V ０ (k, n) Ｈ We perform singular value decomposition into the form N Ｒｘ U is a submatrix of a unitary matrix in row R column. ０ And a diagonal matrix D with R rows and R columns, where the diagonal elements are the effective singular values ​​of the interpolation propagation path characteristic H(k,n). ０ (k, n) and N Ｔｘ Submatrix V of a unitary matrix with rows and columns R ０ Adjoint matrix V of (k, n) ０ (k, n) Ｈ A singular value decomposition processing unit (33) calculates the following: The aforementioned N Ｔｘ A test reference signal transmitted from a transmitting antenna, a modulated signal for test data to be transmitted to the object under test, and an N including the test reference signal in the frequency domain and the modulated signal in the frequency domain. Ｔｘ A test signal generation unit (26) that generates parallel test signals and The aforementioned N Ｔｘ The adjoint matrix V is used for the parallel test signals. ０ (k, n) Ｈ By multiplying by the above N Ｔｘ A signal conversion unit (24) that converts parallel test signals into R-parallel signals, A time-domain signal generation unit (25) performs an inverse Fourier transform on the R-parallel signals to generate a time-domain signal, The time-domain signal generated by the time-domain signal generation unit and the submatrix U of the unitary matrix ０ (k, n) and the diagonal matrix D ０ Product U with (k, n) ０ (k, n) D ０ A convolution operation is performed with the impulse response of (k, n), and the N of the object being measured is calculated. Ｒｘ The time domain N received by each receiving antenna Ｒｘ A test system comprising a convolution unit (41) that generates parallel test signals.

3. The aforementioned test signal generation unit is: A modulation signal generation unit (21) that generates the modulation signal in the frequency domain, The aforementioned N Ｔｘ A beamforming process equivalent to a calculation process is performed on the modulated signal in the frequency domain to make the beam characteristics of the radio waves of the downlink signal transmitted from each transmitting antenna a desired characteristic, N Ｔｘ A beamforming processing unit (22) that generates parallel beamforming processing signals, The aforementioned N Ｔｘ The parallel beamforming processing signals are each added to the frequency domain test reference signals, and the N Ｔｘ The test system according to claim 1, further comprising an integration unit (23) that generates parallel test signals.

4. The aforementioned test signal generation unit is: A modulation signal generation unit (21) that generates the modulation signal in the frequency domain, The aforementioned N Ｔｘ A beamforming process equivalent to a calculation process is performed on the modulated signal in the frequency domain to make the beam characteristics of the radio waves of the downlink signal transmitted from each transmitting antenna a desired characteristic, N Ｔｘ A beamforming processing unit (22) that generates parallel beamforming processing signals, The aforementioned N Ｔｘ The parallel beamforming processing signals are each added to the frequency domain test reference signals, and the N Ｔｘ The test system according to claim 2, further comprising an integration unit (23) that generates parallel test signals.

5. The adjoint matrix V ０ (k, n) Ｈ The impulse response and the product U ０ (k, n) D ０ The system further includes a propagation path characteristic storage unit (35) that stores the impulse response of (k,n), The signal conversion unit returns the impulse response of the adjoint matrix V(k,n) read from the propagation path characteristic memory unit to the adjoint matrix V(k,n) in the frequency domain, and then multiplies the adjoint matrix V(k,n) in the frequency domain by the N parallel test signals. ０ (k,n) Ｈ of the adjoint matrix V(k,n) in the frequency domain, and then multiplies the adjoint matrix V(k,n) in the frequency domain by the N parallel test signals. ０ (k,n) Ｈ of the adjoint matrix V(k,n) in the frequency domain, and then multiplies the adjoint matrix V(k,n) in the frequency domain by the N parallel test signals. ０ (k,n) Ｈ of the adjoint matrix V(k,n) in the frequency domain, and then multiplies the adjoint matrix V(k,n) in the frequency domain by the N parallel test signals. Ｔｘ parallel test signals. The convolution operation unit performs a convolution operation between the signal in the time domain generated by the time domain signal generation unit and the impulse response of the product U(k, n)D(k, n) read from the propagation path characteristic storage unit. ０ (k, n)D ０ The test system according to claim 2 or claim 4, characterized in that the convolution operation is performed.

6. The singular value decomposition processing unit is: The product U ０ (k, n) D ０ The elements of (k, n) and the submatrix V of the unitary matrix. ０ The diagonal matrix D such that the elements of the column vectors constituting (k, n) change continuously between adjacent interpolation propagation path characteristics H(k, n) in the frequency axis and time axis. ０ The rearrangement of the singular values ​​that constitute (k, n) and the submatrix U of the unitary matrix ０ Rearrangement and phase adjustment of the column vectors constituting (k, n), and the submatrix V of the unitary matrix. ０ The test system according to claim 2 or 4, characterized by rearranging and adjusting the phase of the column vectors constituting (k, n).

7. The convolution unit processes the time-domain signal which includes the test reference signal and the timing n which includes the test reference signal. ＲＳ The product U ０ (k, n) D ０ The test system according to claim 2 or 4, characterized in that the convolution operation is performed by aligning the timing of the impulse responses of (k, n).

8. N Ｒｘ A test method for transmitting a test signal to an object under test (120) having a number of receiving antennas, N of the network-side transceiver (100) Ｔｘ Individual transmitting antennas (Tx#1 to Tx#N) Ｔｘ The downlink signal transmitted from ) in the environment of the actual propagation path (110) N Ｒｘ Individual receiving antennas (Rx#1 to Rx#N) Ｒｘ Using the reference signal included in the IQ data of the downlink signal output from the antenna device (10) that receives the signal, the subcarrier f ｋ and timing t ｎＲＳ Instantaneous characteristics H(k, n) of the propagation path characteristics of each actual propagation path ＲＳ The actual propagation path characteristics calculation step (S2) calculates the following: The aforementioned instantaneous characteristics H(k, n) ＲＳ An interpolation process step (S3) is performed to interpolate the time axis to generate an interpolated propagation path characteristic H(k,n) of a sampling rate that satisfies the sampling theorem, Let R be the number of valid singular values, and the interpolation propagation path characteristic H(k,n) be H(k,n) = U ０ (k, n) D ０ (k, n) V ０ (k, n) Ｈ We perform singular value decomposition into the form N Ｒｘ U is a submatrix of a unitary matrix in row R column. ０ And a diagonal matrix D with R rows and R columns, where the diagonal elements are the effective singular values ​​of the interpolation propagation path characteristic H(k,n). ０ (k, n) and N Ｔｘ Submatrix V of a unitary matrix with rows and columns R ０ Adjoint matrix V of (k, n) ０ (k, n) Ｈ S4 is a singular value decomposition step to calculate the following: The aforementioned N Ｔｘ A test reference signal transmitted from a transmitting antenna, a modulated signal for test data to be transmitted to the object under test, and an N including the test reference signal in the frequency domain and the modulated signal in the frequency domain. Ｔｘ Steps to generate parallel test signals (S5-S7), The aforementioned N Ｔｘ The adjoint matrix V is used for the parallel test signals. ０ (k, n) Ｈ By multiplying by the above N Ｔｘ A signal conversion step (S8) that converts parallel test signals into R-parallel signals, A time-domain signal generation step (S9) is performed on the R-parallel signals to generate a time-domain signal by performing an inverse Fourier transform, The time-domain signal generated by the time-domain signal generation step and the submatrix U of the unitary matrix ０ (k, n) and the diagonal matrix D ０ Product U with (k, n) ０ (k, n) D ０ A convolution operation is performed with the impulse response of (k, n), and the N of the object being measured is calculated. Ｒｘ The time domain N received by each receiving antenna Ｒｘ A test method comprising a convolution operation step (S10) for generating parallel test signals.

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